1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1MarkSweep.hpp"
35 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
36 #include "gc_implementation/g1/g1RemSet.inline.hpp"
37 #include "gc_implementation/g1/heapRegionRemSet.hpp"
38 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
39 #include "gc_implementation/g1/vm_operations_g1.hpp"
40 #include "gc_implementation/shared/isGCActiveMark.hpp"
41 #include "memory/gcLocker.inline.hpp"
42 #include "memory/genOopClosures.inline.hpp"
43 #include "memory/generationSpec.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.pcgc.inline.hpp"
46 #include "runtime/aprofiler.hpp"
47 #include "runtime/vmThread.hpp"
48
49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
50
51 // turn it on so that the contents of the young list (scan-only /
52 // to-be-collected) are printed at "strategic" points before / during
53 // / after the collection --- this is useful for debugging
54 #define YOUNG_LIST_VERBOSE 0
55 // CURRENT STATUS
56 // This file is under construction. Search for "FIXME".
57
58 // INVARIANTS/NOTES
59 //
60 // All allocation activity covered by the G1CollectedHeap interface is
61 // serialized by acquiring the HeapLock. This happens in mem_allocate
62 // and allocate_new_tlab, which are the "entry" points to the
63 // allocation code from the rest of the JVM. (Note that this does not
64 // apply to TLAB allocation, which is not part of this interface: it
65 // is done by clients of this interface.)
66
67 // Local to this file.
68
69 class RefineCardTableEntryClosure: public CardTableEntryClosure {
70 SuspendibleThreadSet* _sts;
71 G1RemSet* _g1rs;
72 ConcurrentG1Refine* _cg1r;
73 bool _concurrent;
74 public:
75 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
76 G1RemSet* g1rs,
77 ConcurrentG1Refine* cg1r) :
78 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
79 {}
80 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
81 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
82 // This path is executed by the concurrent refine or mutator threads,
83 // concurrently, and so we do not care if card_ptr contains references
84 // that point into the collection set.
85 assert(!oops_into_cset, "should be");
86
87 if (_concurrent && _sts->should_yield()) {
88 // Caller will actually yield.
89 return false;
90 }
91 // Otherwise, we finished successfully; return true.
92 return true;
93 }
94 void set_concurrent(bool b) { _concurrent = b; }
95 };
96
97
98 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
99 int _calls;
100 G1CollectedHeap* _g1h;
101 CardTableModRefBS* _ctbs;
102 int _histo[256];
103 public:
104 ClearLoggedCardTableEntryClosure() :
105 _calls(0)
106 {
107 _g1h = G1CollectedHeap::heap();
108 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
109 for (int i = 0; i < 256; i++) _histo[i] = 0;
110 }
111 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
112 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
113 _calls++;
114 unsigned char* ujb = (unsigned char*)card_ptr;
115 int ind = (int)(*ujb);
116 _histo[ind]++;
117 *card_ptr = -1;
118 }
119 return true;
120 }
121 int calls() { return _calls; }
122 void print_histo() {
123 gclog_or_tty->print_cr("Card table value histogram:");
124 for (int i = 0; i < 256; i++) {
125 if (_histo[i] != 0) {
126 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
127 }
128 }
129 }
130 };
131
132 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
133 int _calls;
134 G1CollectedHeap* _g1h;
135 CardTableModRefBS* _ctbs;
136 public:
137 RedirtyLoggedCardTableEntryClosure() :
138 _calls(0)
139 {
140 _g1h = G1CollectedHeap::heap();
141 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
142 }
143 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
144 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
145 _calls++;
146 *card_ptr = 0;
147 }
148 return true;
149 }
150 int calls() { return _calls; }
151 };
152
153 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
154 public:
155 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
156 *card_ptr = CardTableModRefBS::dirty_card_val();
157 return true;
158 }
159 };
160
161 YoungList::YoungList(G1CollectedHeap* g1h)
162 : _g1h(g1h), _head(NULL),
163 _length(0),
164 _last_sampled_rs_lengths(0),
165 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
166 {
167 guarantee( check_list_empty(false), "just making sure..." );
168 }
169
170 void YoungList::push_region(HeapRegion *hr) {
171 assert(!hr->is_young(), "should not already be young");
172 assert(hr->get_next_young_region() == NULL, "cause it should!");
173
174 hr->set_next_young_region(_head);
175 _head = hr;
176
177 hr->set_young();
178 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
179 ++_length;
180 }
181
182 void YoungList::add_survivor_region(HeapRegion* hr) {
183 assert(hr->is_survivor(), "should be flagged as survivor region");
184 assert(hr->get_next_young_region() == NULL, "cause it should!");
185
186 hr->set_next_young_region(_survivor_head);
187 if (_survivor_head == NULL) {
188 _survivor_tail = hr;
189 }
190 _survivor_head = hr;
191
192 ++_survivor_length;
193 }
194
195 void YoungList::empty_list(HeapRegion* list) {
196 while (list != NULL) {
197 HeapRegion* next = list->get_next_young_region();
198 list->set_next_young_region(NULL);
199 list->uninstall_surv_rate_group();
200 list->set_not_young();
201 list = next;
202 }
203 }
204
205 void YoungList::empty_list() {
206 assert(check_list_well_formed(), "young list should be well formed");
207
208 empty_list(_head);
209 _head = NULL;
210 _length = 0;
211
212 empty_list(_survivor_head);
213 _survivor_head = NULL;
214 _survivor_tail = NULL;
215 _survivor_length = 0;
216
217 _last_sampled_rs_lengths = 0;
218
219 assert(check_list_empty(false), "just making sure...");
220 }
221
222 bool YoungList::check_list_well_formed() {
223 bool ret = true;
224
225 size_t length = 0;
226 HeapRegion* curr = _head;
227 HeapRegion* last = NULL;
228 while (curr != NULL) {
229 if (!curr->is_young()) {
230 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
231 "incorrectly tagged (y: %d, surv: %d)",
232 curr->bottom(), curr->end(),
233 curr->is_young(), curr->is_survivor());
234 ret = false;
235 }
236 ++length;
237 last = curr;
238 curr = curr->get_next_young_region();
239 }
240 ret = ret && (length == _length);
241
242 if (!ret) {
243 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
244 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
245 length, _length);
246 }
247
248 return ret;
249 }
250
251 bool YoungList::check_list_empty(bool check_sample) {
252 bool ret = true;
253
254 if (_length != 0) {
255 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
256 _length);
257 ret = false;
258 }
259 if (check_sample && _last_sampled_rs_lengths != 0) {
260 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
261 ret = false;
262 }
263 if (_head != NULL) {
264 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
265 ret = false;
266 }
267 if (!ret) {
268 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
269 }
270
271 return ret;
272 }
273
274 void
275 YoungList::rs_length_sampling_init() {
276 _sampled_rs_lengths = 0;
277 _curr = _head;
278 }
279
280 bool
281 YoungList::rs_length_sampling_more() {
282 return _curr != NULL;
283 }
284
285 void
286 YoungList::rs_length_sampling_next() {
287 assert( _curr != NULL, "invariant" );
288 size_t rs_length = _curr->rem_set()->occupied();
289
290 _sampled_rs_lengths += rs_length;
291
292 // The current region may not yet have been added to the
293 // incremental collection set (it gets added when it is
294 // retired as the current allocation region).
295 if (_curr->in_collection_set()) {
296 // Update the collection set policy information for this region
297 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
298 }
299
300 _curr = _curr->get_next_young_region();
301 if (_curr == NULL) {
302 _last_sampled_rs_lengths = _sampled_rs_lengths;
303 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
304 }
305 }
306
307 void
308 YoungList::reset_auxilary_lists() {
309 guarantee( is_empty(), "young list should be empty" );
310 assert(check_list_well_formed(), "young list should be well formed");
311
312 // Add survivor regions to SurvRateGroup.
313 _g1h->g1_policy()->note_start_adding_survivor_regions();
314 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
315
316 for (HeapRegion* curr = _survivor_head;
317 curr != NULL;
318 curr = curr->get_next_young_region()) {
319 _g1h->g1_policy()->set_region_survivors(curr);
320
321 // The region is a non-empty survivor so let's add it to
322 // the incremental collection set for the next evacuation
323 // pause.
324 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
325 }
326 _g1h->g1_policy()->note_stop_adding_survivor_regions();
327
328 _head = _survivor_head;
329 _length = _survivor_length;
330 if (_survivor_head != NULL) {
331 assert(_survivor_tail != NULL, "cause it shouldn't be");
332 assert(_survivor_length > 0, "invariant");
333 _survivor_tail->set_next_young_region(NULL);
334 }
335
336 // Don't clear the survivor list handles until the start of
337 // the next evacuation pause - we need it in order to re-tag
338 // the survivor regions from this evacuation pause as 'young'
339 // at the start of the next.
340
341 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
342
343 assert(check_list_well_formed(), "young list should be well formed");
344 }
345
346 void YoungList::print() {
347 HeapRegion* lists[] = {_head, _survivor_head};
348 const char* names[] = {"YOUNG", "SURVIVOR"};
349
350 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
351 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
352 HeapRegion *curr = lists[list];
353 if (curr == NULL)
354 gclog_or_tty->print_cr(" empty");
355 while (curr != NULL) {
356 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
357 "age: %4d, y: %d, surv: %d",
358 curr->bottom(), curr->end(),
359 curr->top(),
360 curr->prev_top_at_mark_start(),
361 curr->next_top_at_mark_start(),
362 curr->top_at_conc_mark_count(),
363 curr->age_in_surv_rate_group_cond(),
364 curr->is_young(),
365 curr->is_survivor());
366 curr = curr->get_next_young_region();
367 }
368 }
369
370 gclog_or_tty->print_cr("");
371 }
372
373 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
374 {
375 // Claim the right to put the region on the dirty cards region list
376 // by installing a self pointer.
377 HeapRegion* next = hr->get_next_dirty_cards_region();
378 if (next == NULL) {
379 HeapRegion* res = (HeapRegion*)
380 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
381 NULL);
382 if (res == NULL) {
383 HeapRegion* head;
384 do {
385 // Put the region to the dirty cards region list.
386 head = _dirty_cards_region_list;
387 next = (HeapRegion*)
388 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
389 if (next == head) {
390 assert(hr->get_next_dirty_cards_region() == hr,
391 "hr->get_next_dirty_cards_region() != hr");
392 if (next == NULL) {
393 // The last region in the list points to itself.
394 hr->set_next_dirty_cards_region(hr);
395 } else {
396 hr->set_next_dirty_cards_region(next);
397 }
398 }
399 } while (next != head);
400 }
401 }
402 }
403
404 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
405 {
406 HeapRegion* head;
407 HeapRegion* hr;
408 do {
409 head = _dirty_cards_region_list;
410 if (head == NULL) {
411 return NULL;
412 }
413 HeapRegion* new_head = head->get_next_dirty_cards_region();
414 if (head == new_head) {
415 // The last region.
416 new_head = NULL;
417 }
418 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
419 head);
420 } while (hr != head);
421 assert(hr != NULL, "invariant");
422 hr->set_next_dirty_cards_region(NULL);
423 return hr;
424 }
425
426 void G1CollectedHeap::stop_conc_gc_threads() {
427 _cg1r->stop();
428 _cmThread->stop();
429 }
430
431 #ifdef ASSERT
432 // A region is added to the collection set as it is retired
433 // so an address p can point to a region which will be in the
434 // collection set but has not yet been retired. This method
435 // therefore is only accurate during a GC pause after all
436 // regions have been retired. It is used for debugging
437 // to check if an nmethod has references to objects that can
438 // be move during a partial collection. Though it can be
439 // inaccurate, it is sufficient for G1 because the conservative
440 // implementation of is_scavengable() for G1 will indicate that
441 // all nmethods must be scanned during a partial collection.
442 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
443 HeapRegion* hr = heap_region_containing(p);
444 return hr != NULL && hr->in_collection_set();
445 }
446 #endif
447
448 // Returns true if the reference points to an object that
449 // can move in an incremental collecction.
450 bool G1CollectedHeap::is_scavengable(const void* p) {
451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
452 G1CollectorPolicy* g1p = g1h->g1_policy();
453 HeapRegion* hr = heap_region_containing(p);
454 if (hr == NULL) {
455 // perm gen (or null)
456 return false;
457 } else {
458 return !hr->isHumongous();
459 }
460 }
461
462 void G1CollectedHeap::check_ct_logs_at_safepoint() {
463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
464 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
465
466 // Count the dirty cards at the start.
467 CountNonCleanMemRegionClosure count1(this);
468 ct_bs->mod_card_iterate(&count1);
469 int orig_count = count1.n();
470
471 // First clear the logged cards.
472 ClearLoggedCardTableEntryClosure clear;
473 dcqs.set_closure(&clear);
474 dcqs.apply_closure_to_all_completed_buffers();
475 dcqs.iterate_closure_all_threads(false);
476 clear.print_histo();
477
478 // Now ensure that there's no dirty cards.
479 CountNonCleanMemRegionClosure count2(this);
480 ct_bs->mod_card_iterate(&count2);
481 if (count2.n() != 0) {
482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 count2.n(), orig_count);
484 }
485 guarantee(count2.n() == 0, "Card table should be clean.");
486
487 RedirtyLoggedCardTableEntryClosure redirty;
488 JavaThread::dirty_card_queue_set().set_closure(&redirty);
489 dcqs.apply_closure_to_all_completed_buffers();
490 dcqs.iterate_closure_all_threads(false);
491 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
492 clear.calls(), orig_count);
493 guarantee(redirty.calls() == clear.calls(),
494 "Or else mechanism is broken.");
495
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503
504 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
505 }
506
507 // Private class members.
508
509 G1CollectedHeap* G1CollectedHeap::_g1h;
510
511 // Private methods.
512
513 HeapRegion*
514 G1CollectedHeap::new_region_try_secondary_free_list() {
515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
516 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
517 if (!_secondary_free_list.is_empty()) {
518 if (G1ConcRegionFreeingVerbose) {
519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
520 "secondary_free_list has "SIZE_FORMAT" entries",
521 _secondary_free_list.length());
522 }
523 // It looks as if there are free regions available on the
524 // secondary_free_list. Let's move them to the free_list and try
525 // again to allocate from it.
526 append_secondary_free_list();
527
528 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
529 "empty we should have moved at least one entry to the free_list");
530 HeapRegion* res = _free_list.remove_head();
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "allocated "HR_FORMAT" from secondary_free_list",
534 HR_FORMAT_PARAMS(res));
535 }
536 return res;
537 }
538
539 // Wait here until we get notifed either when (a) there are no
540 // more free regions coming or (b) some regions have been moved on
541 // the secondary_free_list.
542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
543 }
544
545 if (G1ConcRegionFreeingVerbose) {
546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
547 "could not allocate from secondary_free_list");
548 }
549 return NULL;
550 }
551
552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
553 assert(!isHumongous(word_size) ||
554 word_size <= (size_t) HeapRegion::GrainWords,
555 "the only time we use this to allocate a humongous region is "
556 "when we are allocating a single humongous region");
557
558 HeapRegion* res;
559 if (G1StressConcRegionFreeing) {
560 if (!_secondary_free_list.is_empty()) {
561 if (G1ConcRegionFreeingVerbose) {
562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 "forced to look at the secondary_free_list");
564 }
565 res = new_region_try_secondary_free_list();
566 if (res != NULL) {
567 return res;
568 }
569 }
570 }
571 res = _free_list.remove_head_or_null();
572 if (res == NULL) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "res == NULL, trying the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 }
579 if (res == NULL && do_expand) {
580 if (expand(word_size * HeapWordSize)) {
581 // Even though the heap was expanded, it might not have reached
582 // the desired size. So, we cannot assume that the allocation
583 // will succeed.
584 res = _free_list.remove_head_or_null();
585 }
586 }
587 return res;
588 }
589
590 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
591 size_t word_size) {
592 assert(isHumongous(word_size), "word_size should be humongous");
593 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
594
595 size_t first = G1_NULL_HRS_INDEX;
596 if (num_regions == 1) {
597 // Only one region to allocate, no need to go through the slower
598 // path. The caller will attempt the expasion if this fails, so
599 // let's not try to expand here too.
600 HeapRegion* hr = new_region(word_size, false /* do_expand */);
601 if (hr != NULL) {
602 first = hr->hrs_index();
603 } else {
604 first = G1_NULL_HRS_INDEX;
605 }
606 } else {
607 // We can't allocate humongous regions while cleanupComplete() is
608 // running, since some of the regions we find to be empty might not
609 // yet be added to the free list and it is not straightforward to
610 // know which list they are on so that we can remove them. Note
611 // that we only need to do this if we need to allocate more than
612 // one region to satisfy the current humongous allocation
613 // request. If we are only allocating one region we use the common
614 // region allocation code (see above).
615 wait_while_free_regions_coming();
616 append_secondary_free_list_if_not_empty_with_lock();
617
618 if (free_regions() >= num_regions) {
619 first = _hrs.find_contiguous(num_regions);
620 if (first != G1_NULL_HRS_INDEX) {
621 for (size_t i = first; i < first + num_regions; ++i) {
622 HeapRegion* hr = region_at(i);
623 assert(hr->is_empty(), "sanity");
624 assert(is_on_master_free_list(hr), "sanity");
625 hr->set_pending_removal(true);
626 }
627 _free_list.remove_all_pending(num_regions);
628 }
629 }
630 }
631 return first;
632 }
633
634 HeapWord*
635 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
636 size_t num_regions,
637 size_t word_size) {
638 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
639 assert(isHumongous(word_size), "word_size should be humongous");
640 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
641
642 // Index of last region in the series + 1.
643 size_t last = first + num_regions;
644
645 // We need to initialize the region(s) we just discovered. This is
646 // a bit tricky given that it can happen concurrently with
647 // refinement threads refining cards on these regions and
648 // potentially wanting to refine the BOT as they are scanning
649 // those cards (this can happen shortly after a cleanup; see CR
650 // 6991377). So we have to set up the region(s) carefully and in
651 // a specific order.
652
653 // The word size sum of all the regions we will allocate.
654 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
655 assert(word_size <= word_size_sum, "sanity");
656
657 // This will be the "starts humongous" region.
658 HeapRegion* first_hr = region_at(first);
659 // The header of the new object will be placed at the bottom of
660 // the first region.
661 HeapWord* new_obj = first_hr->bottom();
662 // This will be the new end of the first region in the series that
663 // should also match the end of the last region in the seriers.
664 HeapWord* new_end = new_obj + word_size_sum;
665 // This will be the new top of the first region that will reflect
666 // this allocation.
667 HeapWord* new_top = new_obj + word_size;
668
669 // First, we need to zero the header of the space that we will be
670 // allocating. When we update top further down, some refinement
671 // threads might try to scan the region. By zeroing the header we
672 // ensure that any thread that will try to scan the region will
673 // come across the zero klass word and bail out.
674 //
675 // NOTE: It would not have been correct to have used
676 // CollectedHeap::fill_with_object() and make the space look like
677 // an int array. The thread that is doing the allocation will
678 // later update the object header to a potentially different array
679 // type and, for a very short period of time, the klass and length
680 // fields will be inconsistent. This could cause a refinement
681 // thread to calculate the object size incorrectly.
682 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
683
684 // We will set up the first region as "starts humongous". This
685 // will also update the BOT covering all the regions to reflect
686 // that there is a single object that starts at the bottom of the
687 // first region.
688 first_hr->set_startsHumongous(new_top, new_end);
689
690 // Then, if there are any, we will set up the "continues
691 // humongous" regions.
692 HeapRegion* hr = NULL;
693 for (size_t i = first + 1; i < last; ++i) {
694 hr = region_at(i);
695 hr->set_continuesHumongous(first_hr);
696 }
697 // If we have "continues humongous" regions (hr != NULL), then the
698 // end of the last one should match new_end.
699 assert(hr == NULL || hr->end() == new_end, "sanity");
700
701 // Up to this point no concurrent thread would have been able to
702 // do any scanning on any region in this series. All the top
703 // fields still point to bottom, so the intersection between
704 // [bottom,top] and [card_start,card_end] will be empty. Before we
705 // update the top fields, we'll do a storestore to make sure that
706 // no thread sees the update to top before the zeroing of the
707 // object header and the BOT initialization.
708 OrderAccess::storestore();
709
710 // Now that the BOT and the object header have been initialized,
711 // we can update top of the "starts humongous" region.
712 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
713 "new_top should be in this region");
714 first_hr->set_top(new_top);
715 if (_hr_printer.is_active()) {
716 HeapWord* bottom = first_hr->bottom();
717 HeapWord* end = first_hr->orig_end();
718 if ((first + 1) == last) {
719 // the series has a single humongous region
720 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
721 } else {
722 // the series has more than one humongous regions
723 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
724 }
725 }
726
727 // Now, we will update the top fields of the "continues humongous"
728 // regions. The reason we need to do this is that, otherwise,
729 // these regions would look empty and this will confuse parts of
730 // G1. For example, the code that looks for a consecutive number
731 // of empty regions will consider them empty and try to
732 // re-allocate them. We can extend is_empty() to also include
733 // !continuesHumongous(), but it is easier to just update the top
734 // fields here. The way we set top for all regions (i.e., top ==
735 // end for all regions but the last one, top == new_top for the
736 // last one) is actually used when we will free up the humongous
737 // region in free_humongous_region().
738 hr = NULL;
739 for (size_t i = first + 1; i < last; ++i) {
740 hr = region_at(i);
741 if ((i + 1) == last) {
742 // last continues humongous region
743 assert(hr->bottom() < new_top && new_top <= hr->end(),
744 "new_top should fall on this region");
745 hr->set_top(new_top);
746 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
747 } else {
748 // not last one
749 assert(new_top > hr->end(), "new_top should be above this region");
750 hr->set_top(hr->end());
751 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
752 }
753 }
754 // If we have continues humongous regions (hr != NULL), then the
755 // end of the last one should match new_end and its top should
756 // match new_top.
757 assert(hr == NULL ||
758 (hr->end() == new_end && hr->top() == new_top), "sanity");
759
760 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
761 _summary_bytes_used += first_hr->used();
762 _humongous_set.add(first_hr);
763
764 return new_obj;
765 }
766
767 // If could fit into free regions w/o expansion, try.
768 // Otherwise, if can expand, do so.
769 // Otherwise, if using ex regions might help, try with ex given back.
770 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
771 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
772
773 verify_region_sets_optional();
774
775 size_t num_regions =
776 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
777 size_t x_size = expansion_regions();
778 size_t fs = _hrs.free_suffix();
779 size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
780 if (first == G1_NULL_HRS_INDEX) {
781 // The only thing we can do now is attempt expansion.
782 if (fs + x_size >= num_regions) {
783 // If the number of regions we're trying to allocate for this
784 // object is at most the number of regions in the free suffix,
785 // then the call to humongous_obj_allocate_find_first() above
786 // should have succeeded and we wouldn't be here.
787 //
788 // We should only be trying to expand when the free suffix is
789 // not sufficient for the object _and_ we have some expansion
790 // room available.
791 assert(num_regions > fs, "earlier allocation should have succeeded");
792
793 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
794 // Even though the heap was expanded, it might not have
795 // reached the desired size. So, we cannot assume that the
796 // allocation will succeed.
797 first = humongous_obj_allocate_find_first(num_regions, word_size);
798 }
799 }
800 }
801
802 HeapWord* result = NULL;
803 if (first != G1_NULL_HRS_INDEX) {
804 result =
805 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
806 assert(result != NULL, "it should always return a valid result");
807 }
808
809 verify_region_sets_optional();
810
811 return result;
812 }
813
814 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
815 assert_heap_not_locked_and_not_at_safepoint();
816 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
817
818 unsigned int dummy_gc_count_before;
819 return attempt_allocation(word_size, &dummy_gc_count_before);
820 }
821
822 HeapWord*
823 G1CollectedHeap::mem_allocate(size_t word_size,
824 bool* gc_overhead_limit_was_exceeded) {
825 assert_heap_not_locked_and_not_at_safepoint();
826
827 // Loop until the allocation is satisified, or unsatisfied after GC.
828 for (int try_count = 1; /* we'll return */; try_count += 1) {
829 unsigned int gc_count_before;
830
831 HeapWord* result = NULL;
832 if (!isHumongous(word_size)) {
833 result = attempt_allocation(word_size, &gc_count_before);
834 } else {
835 result = attempt_allocation_humongous(word_size, &gc_count_before);
836 }
837 if (result != NULL) {
838 return result;
839 }
840
841 // Create the garbage collection operation...
842 VM_G1CollectForAllocation op(gc_count_before, word_size);
843 // ...and get the VM thread to execute it.
844 VMThread::execute(&op);
845
846 if (op.prologue_succeeded() && op.pause_succeeded()) {
847 // If the operation was successful we'll return the result even
848 // if it is NULL. If the allocation attempt failed immediately
849 // after a Full GC, it's unlikely we'll be able to allocate now.
850 HeapWord* result = op.result();
851 if (result != NULL && !isHumongous(word_size)) {
852 // Allocations that take place on VM operations do not do any
853 // card dirtying and we have to do it here. We only have to do
854 // this for non-humongous allocations, though.
855 dirty_young_block(result, word_size);
856 }
857 return result;
858 } else {
859 assert(op.result() == NULL,
860 "the result should be NULL if the VM op did not succeed");
861 }
862
863 // Give a warning if we seem to be looping forever.
864 if ((QueuedAllocationWarningCount > 0) &&
865 (try_count % QueuedAllocationWarningCount == 0)) {
866 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
867 }
868 }
869
870 ShouldNotReachHere();
871 return NULL;
872 }
873
874 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
875 unsigned int *gc_count_before_ret) {
876 // Make sure you read the note in attempt_allocation_humongous().
877
878 assert_heap_not_locked_and_not_at_safepoint();
879 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
880 "be called for humongous allocation requests");
881
882 // We should only get here after the first-level allocation attempt
883 // (attempt_allocation()) failed to allocate.
884
885 // We will loop until a) we manage to successfully perform the
886 // allocation or b) we successfully schedule a collection which
887 // fails to perform the allocation. b) is the only case when we'll
888 // return NULL.
889 HeapWord* result = NULL;
890 for (int try_count = 1; /* we'll return */; try_count += 1) {
891 bool should_try_gc;
892 unsigned int gc_count_before;
893
894 {
895 MutexLockerEx x(Heap_lock);
896
897 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
898 false /* bot_updates */);
899 if (result != NULL) {
900 return result;
901 }
902
903 // If we reach here, attempt_allocation_locked() above failed to
904 // allocate a new region. So the mutator alloc region should be NULL.
905 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
906
907 if (GC_locker::is_active_and_needs_gc()) {
908 if (g1_policy()->can_expand_young_list()) {
909 result = _mutator_alloc_region.attempt_allocation_force(word_size,
910 false /* bot_updates */);
911 if (result != NULL) {
912 return result;
913 }
914 }
915 should_try_gc = false;
916 } else {
917 // Read the GC count while still holding the Heap_lock.
918 gc_count_before = SharedHeap::heap()->total_collections();
919 should_try_gc = true;
920 }
921 }
922
923 if (should_try_gc) {
924 bool succeeded;
925 result = do_collection_pause(word_size, gc_count_before, &succeeded);
926 if (result != NULL) {
927 assert(succeeded, "only way to get back a non-NULL result");
928 return result;
929 }
930
931 if (succeeded) {
932 // If we get here we successfully scheduled a collection which
933 // failed to allocate. No point in trying to allocate
934 // further. We'll just return NULL.
935 MutexLockerEx x(Heap_lock);
936 *gc_count_before_ret = SharedHeap::heap()->total_collections();
937 return NULL;
938 }
939 } else {
940 GC_locker::stall_until_clear();
941 }
942
943 // We can reach here if we were unsuccessul in scheduling a
944 // collection (because another thread beat us to it) or if we were
945 // stalled due to the GC locker. In either can we should retry the
946 // allocation attempt in case another thread successfully
947 // performed a collection and reclaimed enough space. We do the
948 // first attempt (without holding the Heap_lock) here and the
949 // follow-on attempt will be at the start of the next loop
950 // iteration (after taking the Heap_lock).
951 result = _mutator_alloc_region.attempt_allocation(word_size,
952 false /* bot_updates */);
953 if (result != NULL ){
954 return result;
955 }
956
957 // Give a warning if we seem to be looping forever.
958 if ((QueuedAllocationWarningCount > 0) &&
959 (try_count % QueuedAllocationWarningCount == 0)) {
960 warning("G1CollectedHeap::attempt_allocation_slow() "
961 "retries %d times", try_count);
962 }
963 }
964
965 ShouldNotReachHere();
966 return NULL;
967 }
968
969 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
970 unsigned int * gc_count_before_ret) {
971 // The structure of this method has a lot of similarities to
972 // attempt_allocation_slow(). The reason these two were not merged
973 // into a single one is that such a method would require several "if
974 // allocation is not humongous do this, otherwise do that"
975 // conditional paths which would obscure its flow. In fact, an early
976 // version of this code did use a unified method which was harder to
977 // follow and, as a result, it had subtle bugs that were hard to
978 // track down. So keeping these two methods separate allows each to
979 // be more readable. It will be good to keep these two in sync as
980 // much as possible.
981
982 assert_heap_not_locked_and_not_at_safepoint();
983 assert(isHumongous(word_size), "attempt_allocation_humongous() "
984 "should only be called for humongous allocations");
985
986 // We will loop until a) we manage to successfully perform the
987 // allocation or b) we successfully schedule a collection which
988 // fails to perform the allocation. b) is the only case when we'll
989 // return NULL.
990 HeapWord* result = NULL;
991 for (int try_count = 1; /* we'll return */; try_count += 1) {
992 bool should_try_gc;
993 unsigned int gc_count_before;
994
995 {
996 MutexLockerEx x(Heap_lock);
997
998 // Given that humongous objects are not allocated in young
999 // regions, we'll first try to do the allocation without doing a
1000 // collection hoping that there's enough space in the heap.
1001 result = humongous_obj_allocate(word_size);
1002 if (result != NULL) {
1003 return result;
1004 }
1005
1006 if (GC_locker::is_active_and_needs_gc()) {
1007 should_try_gc = false;
1008 } else {
1009 // Read the GC count while still holding the Heap_lock.
1010 gc_count_before = SharedHeap::heap()->total_collections();
1011 should_try_gc = true;
1012 }
1013 }
1014
1015 if (should_try_gc) {
1016 // If we failed to allocate the humongous object, we should try to
1017 // do a collection pause (if we're allowed) in case it reclaims
1018 // enough space for the allocation to succeed after the pause.
1019
1020 bool succeeded;
1021 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1022 if (result != NULL) {
1023 assert(succeeded, "only way to get back a non-NULL result");
1024 return result;
1025 }
1026
1027 if (succeeded) {
1028 // If we get here we successfully scheduled a collection which
1029 // failed to allocate. No point in trying to allocate
1030 // further. We'll just return NULL.
1031 MutexLockerEx x(Heap_lock);
1032 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1033 return NULL;
1034 }
1035 } else {
1036 GC_locker::stall_until_clear();
1037 }
1038
1039 // We can reach here if we were unsuccessul in scheduling a
1040 // collection (because another thread beat us to it) or if we were
1041 // stalled due to the GC locker. In either can we should retry the
1042 // allocation attempt in case another thread successfully
1043 // performed a collection and reclaimed enough space. Give a
1044 // warning if we seem to be looping forever.
1045
1046 if ((QueuedAllocationWarningCount > 0) &&
1047 (try_count % QueuedAllocationWarningCount == 0)) {
1048 warning("G1CollectedHeap::attempt_allocation_humongous() "
1049 "retries %d times", try_count);
1050 }
1051 }
1052
1053 ShouldNotReachHere();
1054 return NULL;
1055 }
1056
1057 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1058 bool expect_null_mutator_alloc_region) {
1059 assert_at_safepoint(true /* should_be_vm_thread */);
1060 assert(_mutator_alloc_region.get() == NULL ||
1061 !expect_null_mutator_alloc_region,
1062 "the current alloc region was unexpectedly found to be non-NULL");
1063
1064 if (!isHumongous(word_size)) {
1065 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1066 false /* bot_updates */);
1067 } else {
1068 return humongous_obj_allocate(word_size);
1069 }
1070
1071 ShouldNotReachHere();
1072 }
1073
1074 class PostMCRemSetClearClosure: public HeapRegionClosure {
1075 ModRefBarrierSet* _mr_bs;
1076 public:
1077 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1078 bool doHeapRegion(HeapRegion* r) {
1079 r->reset_gc_time_stamp();
1080 if (r->continuesHumongous())
1081 return false;
1082 HeapRegionRemSet* hrrs = r->rem_set();
1083 if (hrrs != NULL) hrrs->clear();
1084 // You might think here that we could clear just the cards
1085 // corresponding to the used region. But no: if we leave a dirty card
1086 // in a region we might allocate into, then it would prevent that card
1087 // from being enqueued, and cause it to be missed.
1088 // Re: the performance cost: we shouldn't be doing full GC anyway!
1089 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1090 return false;
1091 }
1092 };
1093
1094
1095 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1096 ModRefBarrierSet* _mr_bs;
1097 public:
1098 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1099 bool doHeapRegion(HeapRegion* r) {
1100 if (r->continuesHumongous()) return false;
1101 if (r->used_region().word_size() != 0) {
1102 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1103 }
1104 return false;
1105 }
1106 };
1107
1108 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1109 G1CollectedHeap* _g1h;
1110 UpdateRSOopClosure _cl;
1111 int _worker_i;
1112 public:
1113 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1114 _cl(g1->g1_rem_set(), worker_i),
1115 _worker_i(worker_i),
1116 _g1h(g1)
1117 { }
1118
1119 bool doHeapRegion(HeapRegion* r) {
1120 if (!r->continuesHumongous()) {
1121 _cl.set_from(r);
1122 r->oop_iterate(&_cl);
1123 }
1124 return false;
1125 }
1126 };
1127
1128 class ParRebuildRSTask: public AbstractGangTask {
1129 G1CollectedHeap* _g1;
1130 public:
1131 ParRebuildRSTask(G1CollectedHeap* g1)
1132 : AbstractGangTask("ParRebuildRSTask"),
1133 _g1(g1)
1134 { }
1135
1136 void work(int i) {
1137 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1138 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1139 HeapRegion::RebuildRSClaimValue);
1140 }
1141 };
1142
1143 class PostCompactionPrinterClosure: public HeapRegionClosure {
1144 private:
1145 G1HRPrinter* _hr_printer;
1146 public:
1147 bool doHeapRegion(HeapRegion* hr) {
1148 assert(!hr->is_young(), "not expecting to find young regions");
1149 // We only generate output for non-empty regions.
1150 if (!hr->is_empty()) {
1151 if (!hr->isHumongous()) {
1152 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1153 } else if (hr->startsHumongous()) {
1154 if (hr->capacity() == (size_t) HeapRegion::GrainBytes) {
1155 // single humongous region
1156 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1157 } else {
1158 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1159 }
1160 } else {
1161 assert(hr->continuesHumongous(), "only way to get here");
1162 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1163 }
1164 }
1165 return false;
1166 }
1167
1168 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1169 : _hr_printer(hr_printer) { }
1170 };
1171
1172 bool G1CollectedHeap::do_collection(bool explicit_gc,
1173 bool clear_all_soft_refs,
1174 size_t word_size) {
1175 assert_at_safepoint(true /* should_be_vm_thread */);
1176
1177 if (GC_locker::check_active_before_gc()) {
1178 return false;
1179 }
1180
1181 SvcGCMarker sgcm(SvcGCMarker::FULL);
1182 ResourceMark rm;
1183
1184 if (PrintHeapAtGC) {
1185 Universe::print_heap_before_gc();
1186 }
1187
1188 verify_region_sets_optional();
1189
1190 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1191 collector_policy()->should_clear_all_soft_refs();
1192
1193 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1194
1195 {
1196 IsGCActiveMark x;
1197
1198 // Timing
1199 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1200 assert(!system_gc || explicit_gc, "invariant");
1201 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1202 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1203 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1204 PrintGC, true, gclog_or_tty);
1205
1206 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1207 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1208
1209 double start = os::elapsedTime();
1210 g1_policy()->record_full_collection_start();
1211
1212 wait_while_free_regions_coming();
1213 append_secondary_free_list_if_not_empty_with_lock();
1214
1215 gc_prologue(true);
1216 increment_total_collections(true /* full gc */);
1217
1218 size_t g1h_prev_used = used();
1219 assert(used() == recalculate_used(), "Should be equal");
1220
1221 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1222 HandleMark hm; // Discard invalid handles created during verification
1223 gclog_or_tty->print(" VerifyBeforeGC:");
1224 prepare_for_verify();
1225 Universe::verify(/* allow dirty */ true,
1226 /* silent */ false,
1227 /* option */ VerifyOption_G1UsePrevMarking);
1228
1229 }
1230
1231 COMPILER2_PRESENT(DerivedPointerTable::clear());
1232
1233 // We want to discover references, but not process them yet.
1234 // This mode is disabled in
1235 // instanceRefKlass::process_discovered_references if the
1236 // generation does some collection work, or
1237 // instanceRefKlass::enqueue_discovered_references if the
1238 // generation returns without doing any work.
1239 ref_processor()->disable_discovery();
1240 ref_processor()->abandon_partial_discovery();
1241 ref_processor()->verify_no_references_recorded();
1242
1243 // Abandon current iterations of concurrent marking and concurrent
1244 // refinement, if any are in progress.
1245 concurrent_mark()->abort();
1246
1247 // Make sure we'll choose a new allocation region afterwards.
1248 release_mutator_alloc_region();
1249 abandon_gc_alloc_regions();
1250 g1_rem_set()->cleanupHRRS();
1251 tear_down_region_lists();
1252
1253 // We should call this after we retire any currently active alloc
1254 // regions so that all the ALLOC / RETIRE events are generated
1255 // before the start GC event.
1256 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1257
1258 // We may have added regions to the current incremental collection
1259 // set between the last GC or pause and now. We need to clear the
1260 // incremental collection set and then start rebuilding it afresh
1261 // after this full GC.
1262 abandon_collection_set(g1_policy()->inc_cset_head());
1263 g1_policy()->clear_incremental_cset();
1264 g1_policy()->stop_incremental_cset_building();
1265
1266 if (g1_policy()->in_young_gc_mode()) {
1267 empty_young_list();
1268 g1_policy()->set_full_young_gcs(true);
1269 }
1270
1271 // See the comment in G1CollectedHeap::ref_processing_init() about
1272 // how reference processing currently works in G1.
1273
1274 // Temporarily make reference _discovery_ single threaded (non-MT).
1275 ReferenceProcessorMTDiscoveryMutator rp_disc_ser(ref_processor(), false);
1276
1277 // Temporarily make refs discovery atomic
1278 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
1279
1280 // Temporarily clear _is_alive_non_header
1281 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
1282
1283 ref_processor()->enable_discovery();
1284 ref_processor()->setup_policy(do_clear_all_soft_refs);
1285 // Do collection work
1286 {
1287 HandleMark hm; // Discard invalid handles created during gc
1288 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
1289 }
1290 assert(free_regions() == 0, "we should not have added any free regions");
1291 rebuild_region_lists();
1292
1293 _summary_bytes_used = recalculate_used();
1294
1295 ref_processor()->enqueue_discovered_references();
1296
1297 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1298
1299 MemoryService::track_memory_usage();
1300
1301 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1302 HandleMark hm; // Discard invalid handles created during verification
1303 gclog_or_tty->print(" VerifyAfterGC:");
1304 prepare_for_verify();
1305 Universe::verify(/* allow dirty */ false,
1306 /* silent */ false,
1307 /* option */ VerifyOption_G1UsePrevMarking);
1308
1309 }
1310 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1311
1312 reset_gc_time_stamp();
1313 // Since everything potentially moved, we will clear all remembered
1314 // sets, and clear all cards. Later we will rebuild remebered
1315 // sets. We will also reset the GC time stamps of the regions.
1316 PostMCRemSetClearClosure rs_clear(mr_bs());
1317 heap_region_iterate(&rs_clear);
1318
1319 // Resize the heap if necessary.
1320 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1321
1322 if (_hr_printer.is_active()) {
1323 // We should do this after we potentially resize the heap so
1324 // that all the COMMIT / UNCOMMIT events are generated before
1325 // the end GC event.
1326
1327 PostCompactionPrinterClosure cl(hr_printer());
1328 heap_region_iterate(&cl);
1329
1330 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1331 }
1332
1333 if (_cg1r->use_cache()) {
1334 _cg1r->clear_and_record_card_counts();
1335 _cg1r->clear_hot_cache();
1336 }
1337
1338 // Rebuild remembered sets of all regions.
1339
1340 if (G1CollectedHeap::use_parallel_gc_threads()) {
1341 ParRebuildRSTask rebuild_rs_task(this);
1342 assert(check_heap_region_claim_values(
1343 HeapRegion::InitialClaimValue), "sanity check");
1344 set_par_threads(workers()->total_workers());
1345 workers()->run_task(&rebuild_rs_task);
1346 set_par_threads(0);
1347 assert(check_heap_region_claim_values(
1348 HeapRegion::RebuildRSClaimValue), "sanity check");
1349 reset_heap_region_claim_values();
1350 } else {
1351 RebuildRSOutOfRegionClosure rebuild_rs(this);
1352 heap_region_iterate(&rebuild_rs);
1353 }
1354
1355 if (PrintGC) {
1356 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1357 }
1358
1359 if (true) { // FIXME
1360 // Ask the permanent generation to adjust size for full collections
1361 perm()->compute_new_size();
1362 }
1363
1364 // Start a new incremental collection set for the next pause
1365 assert(g1_policy()->collection_set() == NULL, "must be");
1366 g1_policy()->start_incremental_cset_building();
1367
1368 // Clear the _cset_fast_test bitmap in anticipation of adding
1369 // regions to the incremental collection set for the next
1370 // evacuation pause.
1371 clear_cset_fast_test();
1372
1373 init_mutator_alloc_region();
1374
1375 double end = os::elapsedTime();
1376 g1_policy()->record_full_collection_end();
1377
1378 #ifdef TRACESPINNING
1379 ParallelTaskTerminator::print_termination_counts();
1380 #endif
1381
1382 gc_epilogue(true);
1383
1384 // Discard all rset updates
1385 JavaThread::dirty_card_queue_set().abandon_logs();
1386 assert(!G1DeferredRSUpdate
1387 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1388 }
1389
1390 if (g1_policy()->in_young_gc_mode()) {
1391 _young_list->reset_sampled_info();
1392 // At this point there should be no regions in the
1393 // entire heap tagged as young.
1394 assert( check_young_list_empty(true /* check_heap */),
1395 "young list should be empty at this point");
1396 }
1397
1398 // Update the number of full collections that have been completed.
1399 increment_full_collections_completed(false /* concurrent */);
1400
1401 _hrs.verify_optional();
1402 verify_region_sets_optional();
1403
1404 if (PrintHeapAtGC) {
1405 Universe::print_heap_after_gc();
1406 }
1407 g1mm()->update_counters();
1408
1409 return true;
1410 }
1411
1412 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1413 // do_collection() will return whether it succeeded in performing
1414 // the GC. Currently, there is no facility on the
1415 // do_full_collection() API to notify the caller than the collection
1416 // did not succeed (e.g., because it was locked out by the GC
1417 // locker). So, right now, we'll ignore the return value.
1418 bool dummy = do_collection(true, /* explicit_gc */
1419 clear_all_soft_refs,
1420 0 /* word_size */);
1421 }
1422
1423 // This code is mostly copied from TenuredGeneration.
1424 void
1425 G1CollectedHeap::
1426 resize_if_necessary_after_full_collection(size_t word_size) {
1427 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1428
1429 // Include the current allocation, if any, and bytes that will be
1430 // pre-allocated to support collections, as "used".
1431 const size_t used_after_gc = used();
1432 const size_t capacity_after_gc = capacity();
1433 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1434
1435 // This is enforced in arguments.cpp.
1436 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1437 "otherwise the code below doesn't make sense");
1438
1439 // We don't have floating point command-line arguments
1440 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1441 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1442 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1443 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1444
1445 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1446 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1447
1448 // We have to be careful here as these two calculations can overflow
1449 // 32-bit size_t's.
1450 double used_after_gc_d = (double) used_after_gc;
1451 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1452 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1453
1454 // Let's make sure that they are both under the max heap size, which
1455 // by default will make them fit into a size_t.
1456 double desired_capacity_upper_bound = (double) max_heap_size;
1457 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1458 desired_capacity_upper_bound);
1459 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1460 desired_capacity_upper_bound);
1461
1462 // We can now safely turn them into size_t's.
1463 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1464 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1465
1466 // This assert only makes sense here, before we adjust them
1467 // with respect to the min and max heap size.
1468 assert(minimum_desired_capacity <= maximum_desired_capacity,
1469 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1470 "maximum_desired_capacity = "SIZE_FORMAT,
1471 minimum_desired_capacity, maximum_desired_capacity));
1472
1473 // Should not be greater than the heap max size. No need to adjust
1474 // it with respect to the heap min size as it's a lower bound (i.e.,
1475 // we'll try to make the capacity larger than it, not smaller).
1476 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1477 // Should not be less than the heap min size. No need to adjust it
1478 // with respect to the heap max size as it's an upper bound (i.e.,
1479 // we'll try to make the capacity smaller than it, not greater).
1480 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1481
1482 if (PrintGC && Verbose) {
1483 const double free_percentage =
1484 (double) free_after_gc / (double) capacity_after_gc;
1485 gclog_or_tty->print_cr("Computing new size after full GC ");
1486 gclog_or_tty->print_cr(" "
1487 " minimum_free_percentage: %6.2f",
1488 minimum_free_percentage);
1489 gclog_or_tty->print_cr(" "
1490 " maximum_free_percentage: %6.2f",
1491 maximum_free_percentage);
1492 gclog_or_tty->print_cr(" "
1493 " capacity: %6.1fK"
1494 " minimum_desired_capacity: %6.1fK"
1495 " maximum_desired_capacity: %6.1fK",
1496 (double) capacity_after_gc / (double) K,
1497 (double) minimum_desired_capacity / (double) K,
1498 (double) maximum_desired_capacity / (double) K);
1499 gclog_or_tty->print_cr(" "
1500 " free_after_gc: %6.1fK"
1501 " used_after_gc: %6.1fK",
1502 (double) free_after_gc / (double) K,
1503 (double) used_after_gc / (double) K);
1504 gclog_or_tty->print_cr(" "
1505 " free_percentage: %6.2f",
1506 free_percentage);
1507 }
1508 if (capacity_after_gc < minimum_desired_capacity) {
1509 // Don't expand unless it's significant
1510 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1511 if (expand(expand_bytes)) {
1512 if (PrintGC && Verbose) {
1513 gclog_or_tty->print_cr(" "
1514 " expanding:"
1515 " max_heap_size: %6.1fK"
1516 " minimum_desired_capacity: %6.1fK"
1517 " expand_bytes: %6.1fK",
1518 (double) max_heap_size / (double) K,
1519 (double) minimum_desired_capacity / (double) K,
1520 (double) expand_bytes / (double) K);
1521 }
1522 }
1523
1524 // No expansion, now see if we want to shrink
1525 } else if (capacity_after_gc > maximum_desired_capacity) {
1526 // Capacity too large, compute shrinking size
1527 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1528 shrink(shrink_bytes);
1529 if (PrintGC && Verbose) {
1530 gclog_or_tty->print_cr(" "
1531 " shrinking:"
1532 " min_heap_size: %6.1fK"
1533 " maximum_desired_capacity: %6.1fK"
1534 " shrink_bytes: %6.1fK",
1535 (double) min_heap_size / (double) K,
1536 (double) maximum_desired_capacity / (double) K,
1537 (double) shrink_bytes / (double) K);
1538 }
1539 }
1540 }
1541
1542
1543 HeapWord*
1544 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1545 bool* succeeded) {
1546 assert_at_safepoint(true /* should_be_vm_thread */);
1547
1548 *succeeded = true;
1549 // Let's attempt the allocation first.
1550 HeapWord* result =
1551 attempt_allocation_at_safepoint(word_size,
1552 false /* expect_null_mutator_alloc_region */);
1553 if (result != NULL) {
1554 assert(*succeeded, "sanity");
1555 return result;
1556 }
1557
1558 // In a G1 heap, we're supposed to keep allocation from failing by
1559 // incremental pauses. Therefore, at least for now, we'll favor
1560 // expansion over collection. (This might change in the future if we can
1561 // do something smarter than full collection to satisfy a failed alloc.)
1562 result = expand_and_allocate(word_size);
1563 if (result != NULL) {
1564 assert(*succeeded, "sanity");
1565 return result;
1566 }
1567
1568 // Expansion didn't work, we'll try to do a Full GC.
1569 bool gc_succeeded = do_collection(false, /* explicit_gc */
1570 false, /* clear_all_soft_refs */
1571 word_size);
1572 if (!gc_succeeded) {
1573 *succeeded = false;
1574 return NULL;
1575 }
1576
1577 // Retry the allocation
1578 result = attempt_allocation_at_safepoint(word_size,
1579 true /* expect_null_mutator_alloc_region */);
1580 if (result != NULL) {
1581 assert(*succeeded, "sanity");
1582 return result;
1583 }
1584
1585 // Then, try a Full GC that will collect all soft references.
1586 gc_succeeded = do_collection(false, /* explicit_gc */
1587 true, /* clear_all_soft_refs */
1588 word_size);
1589 if (!gc_succeeded) {
1590 *succeeded = false;
1591 return NULL;
1592 }
1593
1594 // Retry the allocation once more
1595 result = attempt_allocation_at_safepoint(word_size,
1596 true /* expect_null_mutator_alloc_region */);
1597 if (result != NULL) {
1598 assert(*succeeded, "sanity");
1599 return result;
1600 }
1601
1602 assert(!collector_policy()->should_clear_all_soft_refs(),
1603 "Flag should have been handled and cleared prior to this point");
1604
1605 // What else? We might try synchronous finalization later. If the total
1606 // space available is large enough for the allocation, then a more
1607 // complete compaction phase than we've tried so far might be
1608 // appropriate.
1609 assert(*succeeded, "sanity");
1610 return NULL;
1611 }
1612
1613 // Attempting to expand the heap sufficiently
1614 // to support an allocation of the given "word_size". If
1615 // successful, perform the allocation and return the address of the
1616 // allocated block, or else "NULL".
1617
1618 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1619 assert_at_safepoint(true /* should_be_vm_thread */);
1620
1621 verify_region_sets_optional();
1622
1623 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1624 if (expand(expand_bytes)) {
1625 _hrs.verify_optional();
1626 verify_region_sets_optional();
1627 return attempt_allocation_at_safepoint(word_size,
1628 false /* expect_null_mutator_alloc_region */);
1629 }
1630 return NULL;
1631 }
1632
1633 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1634 HeapWord* new_end) {
1635 assert(old_end != new_end, "don't call this otherwise");
1636 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1637
1638 // Update the committed mem region.
1639 _g1_committed.set_end(new_end);
1640 // Tell the card table about the update.
1641 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1642 // Tell the BOT about the update.
1643 _bot_shared->resize(_g1_committed.word_size());
1644 }
1645
1646 bool G1CollectedHeap::expand(size_t expand_bytes) {
1647 size_t old_mem_size = _g1_storage.committed_size();
1648 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1649 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1650 HeapRegion::GrainBytes);
1651
1652 if (Verbose && PrintGC) {
1653 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK",
1654 old_mem_size/K, aligned_expand_bytes/K);
1655 }
1656
1657 // First commit the memory.
1658 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1659 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1660 if (successful) {
1661 // Then propagate this update to the necessary data structures.
1662 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1663 update_committed_space(old_end, new_end);
1664
1665 FreeRegionList expansion_list("Local Expansion List");
1666 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1667 assert(mr.start() == old_end, "post-condition");
1668 // mr might be a smaller region than what was requested if
1669 // expand_by() was unable to allocate the HeapRegion instances
1670 assert(mr.end() <= new_end, "post-condition");
1671
1672 size_t actual_expand_bytes = mr.byte_size();
1673 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1674 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1675 "post-condition");
1676 if (actual_expand_bytes < aligned_expand_bytes) {
1677 // We could not expand _hrs to the desired size. In this case we
1678 // need to shrink the committed space accordingly.
1679 assert(mr.end() < new_end, "invariant");
1680
1681 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1682 // First uncommit the memory.
1683 _g1_storage.shrink_by(diff_bytes);
1684 // Then propagate this update to the necessary data structures.
1685 update_committed_space(new_end, mr.end());
1686 }
1687 _free_list.add_as_tail(&expansion_list);
1688
1689 if (_hr_printer.is_active()) {
1690 HeapWord* curr = mr.start();
1691 while (curr < mr.end()) {
1692 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1693 _hr_printer.commit(curr, curr_end);
1694 curr = curr_end;
1695 }
1696 assert(curr == mr.end(), "post-condition");
1697 }
1698 } else {
1699 // The expansion of the virtual storage space was unsuccessful.
1700 // Let's see if it was because we ran out of swap.
1701 if (G1ExitOnExpansionFailure &&
1702 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1703 // We had head room...
1704 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1705 }
1706 }
1707
1708 if (Verbose && PrintGC) {
1709 size_t new_mem_size = _g1_storage.committed_size();
1710 gclog_or_tty->print_cr("...%s, expanded to %ldK",
1711 (successful ? "Successful" : "Failed"),
1712 new_mem_size/K);
1713 }
1714 return successful;
1715 }
1716
1717 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1718 size_t old_mem_size = _g1_storage.committed_size();
1719 size_t aligned_shrink_bytes =
1720 ReservedSpace::page_align_size_down(shrink_bytes);
1721 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1722 HeapRegion::GrainBytes);
1723 size_t num_regions_deleted = 0;
1724 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1725 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1726 assert(mr.end() == old_end, "post-condition");
1727 if (mr.byte_size() > 0) {
1728 if (_hr_printer.is_active()) {
1729 HeapWord* curr = mr.end();
1730 while (curr > mr.start()) {
1731 HeapWord* curr_end = curr;
1732 curr -= HeapRegion::GrainWords;
1733 _hr_printer.uncommit(curr, curr_end);
1734 }
1735 assert(curr == mr.start(), "post-condition");
1736 }
1737
1738 _g1_storage.shrink_by(mr.byte_size());
1739 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1740 assert(mr.start() == new_end, "post-condition");
1741
1742 _expansion_regions += num_regions_deleted;
1743 update_committed_space(old_end, new_end);
1744 HeapRegionRemSet::shrink_heap(n_regions());
1745
1746 if (Verbose && PrintGC) {
1747 size_t new_mem_size = _g1_storage.committed_size();
1748 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1749 old_mem_size/K, aligned_shrink_bytes/K,
1750 new_mem_size/K);
1751 }
1752 }
1753 }
1754
1755 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1756 verify_region_sets_optional();
1757
1758 // We should only reach here at the end of a Full GC which means we
1759 // should not not be holding to any GC alloc regions. The method
1760 // below will make sure of that and do any remaining clean up.
1761 abandon_gc_alloc_regions();
1762
1763 // Instead of tearing down / rebuilding the free lists here, we
1764 // could instead use the remove_all_pending() method on free_list to
1765 // remove only the ones that we need to remove.
1766 tear_down_region_lists(); // We will rebuild them in a moment.
1767 shrink_helper(shrink_bytes);
1768 rebuild_region_lists();
1769
1770 _hrs.verify_optional();
1771 verify_region_sets_optional();
1772 }
1773
1774 // Public methods.
1775
1776 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1777 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1778 #endif // _MSC_VER
1779
1780
1781 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1782 SharedHeap(policy_),
1783 _g1_policy(policy_),
1784 _dirty_card_queue_set(false),
1785 _into_cset_dirty_card_queue_set(false),
1786 _is_alive_closure(this),
1787 _ref_processor(NULL),
1788 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1789 _bot_shared(NULL),
1790 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1791 _evac_failure_scan_stack(NULL) ,
1792 _mark_in_progress(false),
1793 _cg1r(NULL), _summary_bytes_used(0),
1794 _refine_cte_cl(NULL),
1795 _full_collection(false),
1796 _free_list("Master Free List"),
1797 _secondary_free_list("Secondary Free List"),
1798 _humongous_set("Master Humongous Set"),
1799 _free_regions_coming(false),
1800 _young_list(new YoungList(this)),
1801 _gc_time_stamp(0),
1802 _retained_old_gc_alloc_region(NULL),
1803 _surviving_young_words(NULL),
1804 _full_collections_completed(0),
1805 _in_cset_fast_test(NULL),
1806 _in_cset_fast_test_base(NULL),
1807 _dirty_cards_region_list(NULL) {
1808 _g1h = this; // To catch bugs.
1809 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1810 vm_exit_during_initialization("Failed necessary allocation.");
1811 }
1812
1813 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1814
1815 int n_queues = MAX2((int)ParallelGCThreads, 1);
1816 _task_queues = new RefToScanQueueSet(n_queues);
1817
1818 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1819 assert(n_rem_sets > 0, "Invariant.");
1820
1821 HeapRegionRemSetIterator** iter_arr =
1822 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1823 for (int i = 0; i < n_queues; i++) {
1824 iter_arr[i] = new HeapRegionRemSetIterator();
1825 }
1826 _rem_set_iterator = iter_arr;
1827
1828 for (int i = 0; i < n_queues; i++) {
1829 RefToScanQueue* q = new RefToScanQueue();
1830 q->initialize();
1831 _task_queues->register_queue(i, q);
1832 }
1833
1834 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1835 }
1836
1837 jint G1CollectedHeap::initialize() {
1838 CollectedHeap::pre_initialize();
1839 os::enable_vtime();
1840
1841 // Necessary to satisfy locking discipline assertions.
1842
1843 MutexLocker x(Heap_lock);
1844
1845 // We have to initialize the printer before committing the heap, as
1846 // it will be used then.
1847 _hr_printer.set_active(G1PrintHeapRegions);
1848
1849 // While there are no constraints in the GC code that HeapWordSize
1850 // be any particular value, there are multiple other areas in the
1851 // system which believe this to be true (e.g. oop->object_size in some
1852 // cases incorrectly returns the size in wordSize units rather than
1853 // HeapWordSize).
1854 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1855
1856 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1857 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1858
1859 // Ensure that the sizes are properly aligned.
1860 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1861 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1862
1863 _cg1r = new ConcurrentG1Refine();
1864
1865 // Reserve the maximum.
1866 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1867 // Includes the perm-gen.
1868
1869 // When compressed oops are enabled, the preferred heap base
1870 // is calculated by subtracting the requested size from the
1871 // 32Gb boundary and using the result as the base address for
1872 // heap reservation. If the requested size is not aligned to
1873 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1874 // into the ReservedHeapSpace constructor) then the actual
1875 // base of the reserved heap may end up differing from the
1876 // address that was requested (i.e. the preferred heap base).
1877 // If this happens then we could end up using a non-optimal
1878 // compressed oops mode.
1879
1880 // Since max_byte_size is aligned to the size of a heap region (checked
1881 // above), we also need to align the perm gen size as it might not be.
1882 const size_t total_reserved = max_byte_size +
1883 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1884 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1885
1886 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1887
1888 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1889 UseLargePages, addr);
1890
1891 if (UseCompressedOops) {
1892 if (addr != NULL && !heap_rs.is_reserved()) {
1893 // Failed to reserve at specified address - the requested memory
1894 // region is taken already, for example, by 'java' launcher.
1895 // Try again to reserver heap higher.
1896 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1897
1898 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1899 UseLargePages, addr);
1900
1901 if (addr != NULL && !heap_rs0.is_reserved()) {
1902 // Failed to reserve at specified address again - give up.
1903 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1904 assert(addr == NULL, "");
1905
1906 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1907 UseLargePages, addr);
1908 heap_rs = heap_rs1;
1909 } else {
1910 heap_rs = heap_rs0;
1911 }
1912 }
1913 }
1914
1915 if (!heap_rs.is_reserved()) {
1916 vm_exit_during_initialization("Could not reserve enough space for object heap");
1917 return JNI_ENOMEM;
1918 }
1919
1920 // It is important to do this in a way such that concurrent readers can't
1921 // temporarily think somethings in the heap. (I've actually seen this
1922 // happen in asserts: DLD.)
1923 _reserved.set_word_size(0);
1924 _reserved.set_start((HeapWord*)heap_rs.base());
1925 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1926
1927 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1928
1929 // Create the gen rem set (and barrier set) for the entire reserved region.
1930 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1931 set_barrier_set(rem_set()->bs());
1932 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1933 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1934 } else {
1935 vm_exit_during_initialization("G1 requires a mod ref bs.");
1936 return JNI_ENOMEM;
1937 }
1938
1939 // Also create a G1 rem set.
1940 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1941 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1942 } else {
1943 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1944 return JNI_ENOMEM;
1945 }
1946
1947 // Carve out the G1 part of the heap.
1948
1949 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1950 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1951 g1_rs.size()/HeapWordSize);
1952 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1953
1954 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1955
1956 _g1_storage.initialize(g1_rs, 0);
1957 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1958 _hrs.initialize((HeapWord*) _g1_reserved.start(),
1959 (HeapWord*) _g1_reserved.end(),
1960 _expansion_regions);
1961
1962 // 6843694 - ensure that the maximum region index can fit
1963 // in the remembered set structures.
1964 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1965 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1966
1967 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1968 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1969 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1970 "too many cards per region");
1971
1972 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
1973
1974 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1975 heap_word_size(init_byte_size));
1976
1977 _g1h = this;
1978
1979 _in_cset_fast_test_length = max_regions();
1980 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1981
1982 // We're biasing _in_cset_fast_test to avoid subtracting the
1983 // beginning of the heap every time we want to index; basically
1984 // it's the same with what we do with the card table.
1985 _in_cset_fast_test = _in_cset_fast_test_base -
1986 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1987
1988 // Clear the _cset_fast_test bitmap in anticipation of adding
1989 // regions to the incremental collection set for the first
1990 // evacuation pause.
1991 clear_cset_fast_test();
1992
1993 // Create the ConcurrentMark data structure and thread.
1994 // (Must do this late, so that "max_regions" is defined.)
1995 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1996 _cmThread = _cm->cmThread();
1997
1998 // Initialize the from_card cache structure of HeapRegionRemSet.
1999 HeapRegionRemSet::init_heap(max_regions());
2000
2001 // Now expand into the initial heap size.
2002 if (!expand(init_byte_size)) {
2003 vm_exit_during_initialization("Failed to allocate initial heap.");
2004 return JNI_ENOMEM;
2005 }
2006
2007 // Perform any initialization actions delegated to the policy.
2008 g1_policy()->init();
2009
2010 g1_policy()->note_start_of_mark_thread();
2011
2012 _refine_cte_cl =
2013 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2014 g1_rem_set(),
2015 concurrent_g1_refine());
2016 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2017
2018 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2019 SATB_Q_FL_lock,
2020 G1SATBProcessCompletedThreshold,
2021 Shared_SATB_Q_lock);
2022
2023 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2024 DirtyCardQ_FL_lock,
2025 concurrent_g1_refine()->yellow_zone(),
2026 concurrent_g1_refine()->red_zone(),
2027 Shared_DirtyCardQ_lock);
2028
2029 if (G1DeferredRSUpdate) {
2030 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2031 DirtyCardQ_FL_lock,
2032 -1, // never trigger processing
2033 -1, // no limit on length
2034 Shared_DirtyCardQ_lock,
2035 &JavaThread::dirty_card_queue_set());
2036 }
2037
2038 // Initialize the card queue set used to hold cards containing
2039 // references into the collection set.
2040 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2041 DirtyCardQ_FL_lock,
2042 -1, // never trigger processing
2043 -1, // no limit on length
2044 Shared_DirtyCardQ_lock,
2045 &JavaThread::dirty_card_queue_set());
2046
2047 // In case we're keeping closure specialization stats, initialize those
2048 // counts and that mechanism.
2049 SpecializationStats::clear();
2050
2051 // Do later initialization work for concurrent refinement.
2052 _cg1r->init();
2053
2054 // Here we allocate the dummy full region that is required by the
2055 // G1AllocRegion class. If we don't pass an address in the reserved
2056 // space here, lots of asserts fire.
2057
2058 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2059 _g1_reserved.start());
2060 // We'll re-use the same region whether the alloc region will
2061 // require BOT updates or not and, if it doesn't, then a non-young
2062 // region will complain that it cannot support allocations without
2063 // BOT updates. So we'll tag the dummy region as young to avoid that.
2064 dummy_region->set_young();
2065 // Make sure it's full.
2066 dummy_region->set_top(dummy_region->end());
2067 G1AllocRegion::setup(this, dummy_region);
2068
2069 init_mutator_alloc_region();
2070
2071 // Do create of the monitoring and management support so that
2072 // values in the heap have been properly initialized.
2073 _g1mm = new G1MonitoringSupport(this, &_g1_storage);
2074
2075 return JNI_OK;
2076 }
2077
2078 void G1CollectedHeap::ref_processing_init() {
2079 // Reference processing in G1 currently works as follows:
2080 //
2081 // * There is only one reference processor instance that
2082 // 'spans' the entire heap. It is created by the code
2083 // below.
2084 // * Reference discovery is not enabled during an incremental
2085 // pause (see 6484982).
2086 // * Discoverered refs are not enqueued nor are they processed
2087 // during an incremental pause (see 6484982).
2088 // * Reference discovery is enabled at initial marking.
2089 // * Reference discovery is disabled and the discovered
2090 // references processed etc during remarking.
2091 // * Reference discovery is MT (see below).
2092 // * Reference discovery requires a barrier (see below).
2093 // * Reference processing is currently not MT (see 6608385).
2094 // * A full GC enables (non-MT) reference discovery and
2095 // processes any discovered references.
2096
2097 SharedHeap::ref_processing_init();
2098 MemRegion mr = reserved_region();
2099 _ref_processor =
2100 new ReferenceProcessor(mr, // span
2101 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
2102 (int) ParallelGCThreads, // degree of mt processing
2103 ParallelGCThreads > 1 || ConcGCThreads > 1, // mt discovery
2104 (int) MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
2105 false, // Reference discovery is not atomic
2106 &_is_alive_closure, // is alive closure for efficiency
2107 true); // Setting next fields of discovered
2108 // lists requires a barrier.
2109 }
2110
2111 size_t G1CollectedHeap::capacity() const {
2112 return _g1_committed.byte_size();
2113 }
2114
2115 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2116 DirtyCardQueue* into_cset_dcq,
2117 bool concurrent,
2118 int worker_i) {
2119 // Clean cards in the hot card cache
2120 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2121
2122 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2123 int n_completed_buffers = 0;
2124 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2125 n_completed_buffers++;
2126 }
2127 g1_policy()->record_update_rs_processed_buffers(worker_i,
2128 (double) n_completed_buffers);
2129 dcqs.clear_n_completed_buffers();
2130 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2131 }
2132
2133
2134 // Computes the sum of the storage used by the various regions.
2135
2136 size_t G1CollectedHeap::used() const {
2137 assert(Heap_lock->owner() != NULL,
2138 "Should be owned on this thread's behalf.");
2139 size_t result = _summary_bytes_used;
2140 // Read only once in case it is set to NULL concurrently
2141 HeapRegion* hr = _mutator_alloc_region.get();
2142 if (hr != NULL)
2143 result += hr->used();
2144 return result;
2145 }
2146
2147 size_t G1CollectedHeap::used_unlocked() const {
2148 size_t result = _summary_bytes_used;
2149 return result;
2150 }
2151
2152 class SumUsedClosure: public HeapRegionClosure {
2153 size_t _used;
2154 public:
2155 SumUsedClosure() : _used(0) {}
2156 bool doHeapRegion(HeapRegion* r) {
2157 if (!r->continuesHumongous()) {
2158 _used += r->used();
2159 }
2160 return false;
2161 }
2162 size_t result() { return _used; }
2163 };
2164
2165 size_t G1CollectedHeap::recalculate_used() const {
2166 SumUsedClosure blk;
2167 heap_region_iterate(&blk);
2168 return blk.result();
2169 }
2170
2171 size_t G1CollectedHeap::unsafe_max_alloc() {
2172 if (free_regions() > 0) return HeapRegion::GrainBytes;
2173 // otherwise, is there space in the current allocation region?
2174
2175 // We need to store the current allocation region in a local variable
2176 // here. The problem is that this method doesn't take any locks and
2177 // there may be other threads which overwrite the current allocation
2178 // region field. attempt_allocation(), for example, sets it to NULL
2179 // and this can happen *after* the NULL check here but before the call
2180 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2181 // to be a problem in the optimized build, since the two loads of the
2182 // current allocation region field are optimized away.
2183 HeapRegion* hr = _mutator_alloc_region.get();
2184 if (hr == NULL) {
2185 return 0;
2186 }
2187 return hr->free();
2188 }
2189
2190 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2191 return
2192 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2193 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2194 }
2195
2196 #ifndef PRODUCT
2197 void G1CollectedHeap::allocate_dummy_regions() {
2198 // Let's fill up most of the region
2199 size_t word_size = HeapRegion::GrainWords - 1024;
2200 // And as a result the region we'll allocate will be humongous.
2201 guarantee(isHumongous(word_size), "sanity");
2202
2203 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2204 // Let's use the existing mechanism for the allocation
2205 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2206 if (dummy_obj != NULL) {
2207 MemRegion mr(dummy_obj, word_size);
2208 CollectedHeap::fill_with_object(mr);
2209 } else {
2210 // If we can't allocate once, we probably cannot allocate
2211 // again. Let's get out of the loop.
2212 break;
2213 }
2214 }
2215 }
2216 #endif // !PRODUCT
2217
2218 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2219 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2220
2221 // We assume that if concurrent == true, then the caller is a
2222 // concurrent thread that was joined the Suspendible Thread
2223 // Set. If there's ever a cheap way to check this, we should add an
2224 // assert here.
2225
2226 // We have already incremented _total_full_collections at the start
2227 // of the GC, so total_full_collections() represents how many full
2228 // collections have been started.
2229 unsigned int full_collections_started = total_full_collections();
2230
2231 // Given that this method is called at the end of a Full GC or of a
2232 // concurrent cycle, and those can be nested (i.e., a Full GC can
2233 // interrupt a concurrent cycle), the number of full collections
2234 // completed should be either one (in the case where there was no
2235 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2236 // behind the number of full collections started.
2237
2238 // This is the case for the inner caller, i.e. a Full GC.
2239 assert(concurrent ||
2240 (full_collections_started == _full_collections_completed + 1) ||
2241 (full_collections_started == _full_collections_completed + 2),
2242 err_msg("for inner caller (Full GC): full_collections_started = %u "
2243 "is inconsistent with _full_collections_completed = %u",
2244 full_collections_started, _full_collections_completed));
2245
2246 // This is the case for the outer caller, i.e. the concurrent cycle.
2247 assert(!concurrent ||
2248 (full_collections_started == _full_collections_completed + 1),
2249 err_msg("for outer caller (concurrent cycle): "
2250 "full_collections_started = %u "
2251 "is inconsistent with _full_collections_completed = %u",
2252 full_collections_started, _full_collections_completed));
2253
2254 _full_collections_completed += 1;
2255
2256 // We need to clear the "in_progress" flag in the CM thread before
2257 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2258 // is set) so that if a waiter requests another System.gc() it doesn't
2259 // incorrectly see that a marking cyle is still in progress.
2260 if (concurrent) {
2261 _cmThread->clear_in_progress();
2262 }
2263
2264 // This notify_all() will ensure that a thread that called
2265 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2266 // and it's waiting for a full GC to finish will be woken up. It is
2267 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2268 FullGCCount_lock->notify_all();
2269 }
2270
2271 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2272 assert_at_safepoint(true /* should_be_vm_thread */);
2273 GCCauseSetter gcs(this, cause);
2274 switch (cause) {
2275 case GCCause::_heap_inspection:
2276 case GCCause::_heap_dump: {
2277 HandleMark hm;
2278 do_full_collection(false); // don't clear all soft refs
2279 break;
2280 }
2281 default: // XXX FIX ME
2282 ShouldNotReachHere(); // Unexpected use of this function
2283 }
2284 }
2285
2286 void G1CollectedHeap::collect(GCCause::Cause cause) {
2287 // The caller doesn't have the Heap_lock
2288 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2289
2290 unsigned int gc_count_before;
2291 unsigned int full_gc_count_before;
2292 {
2293 MutexLocker ml(Heap_lock);
2294
2295 // Read the GC count while holding the Heap_lock
2296 gc_count_before = SharedHeap::heap()->total_collections();
2297 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2298 }
2299
2300 if (should_do_concurrent_full_gc(cause)) {
2301 // Schedule an initial-mark evacuation pause that will start a
2302 // concurrent cycle. We're setting word_size to 0 which means that
2303 // we are not requesting a post-GC allocation.
2304 VM_G1IncCollectionPause op(gc_count_before,
2305 0, /* word_size */
2306 true, /* should_initiate_conc_mark */
2307 g1_policy()->max_pause_time_ms(),
2308 cause);
2309 VMThread::execute(&op);
2310 } else {
2311 if (cause == GCCause::_gc_locker
2312 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2313
2314 // Schedule a standard evacuation pause. We're setting word_size
2315 // to 0 which means that we are not requesting a post-GC allocation.
2316 VM_G1IncCollectionPause op(gc_count_before,
2317 0, /* word_size */
2318 false, /* should_initiate_conc_mark */
2319 g1_policy()->max_pause_time_ms(),
2320 cause);
2321 VMThread::execute(&op);
2322 } else {
2323 // Schedule a Full GC.
2324 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2325 VMThread::execute(&op);
2326 }
2327 }
2328 }
2329
2330 bool G1CollectedHeap::is_in(const void* p) const {
2331 HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p);
2332 if (hr != NULL) {
2333 return hr->is_in(p);
2334 } else {
2335 return _perm_gen->as_gen()->is_in(p);
2336 }
2337 }
2338
2339 // Iteration functions.
2340
2341 // Iterates an OopClosure over all ref-containing fields of objects
2342 // within a HeapRegion.
2343
2344 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2345 MemRegion _mr;
2346 OopClosure* _cl;
2347 public:
2348 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2349 : _mr(mr), _cl(cl) {}
2350 bool doHeapRegion(HeapRegion* r) {
2351 if (! r->continuesHumongous()) {
2352 r->oop_iterate(_cl);
2353 }
2354 return false;
2355 }
2356 };
2357
2358 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2359 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2360 heap_region_iterate(&blk);
2361 if (do_perm) {
2362 perm_gen()->oop_iterate(cl);
2363 }
2364 }
2365
2366 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2367 IterateOopClosureRegionClosure blk(mr, cl);
2368 heap_region_iterate(&blk);
2369 if (do_perm) {
2370 perm_gen()->oop_iterate(cl);
2371 }
2372 }
2373
2374 // Iterates an ObjectClosure over all objects within a HeapRegion.
2375
2376 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2377 ObjectClosure* _cl;
2378 public:
2379 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2380 bool doHeapRegion(HeapRegion* r) {
2381 if (! r->continuesHumongous()) {
2382 r->object_iterate(_cl);
2383 }
2384 return false;
2385 }
2386 };
2387
2388 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2389 IterateObjectClosureRegionClosure blk(cl);
2390 heap_region_iterate(&blk);
2391 if (do_perm) {
2392 perm_gen()->object_iterate(cl);
2393 }
2394 }
2395
2396 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2397 // FIXME: is this right?
2398 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2399 }
2400
2401 // Calls a SpaceClosure on a HeapRegion.
2402
2403 class SpaceClosureRegionClosure: public HeapRegionClosure {
2404 SpaceClosure* _cl;
2405 public:
2406 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2407 bool doHeapRegion(HeapRegion* r) {
2408 _cl->do_space(r);
2409 return false;
2410 }
2411 };
2412
2413 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2414 SpaceClosureRegionClosure blk(cl);
2415 heap_region_iterate(&blk);
2416 }
2417
2418 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2419 _hrs.iterate(cl);
2420 }
2421
2422 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2423 HeapRegionClosure* cl) const {
2424 _hrs.iterate_from(r, cl);
2425 }
2426
2427 void
2428 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2429 int worker,
2430 jint claim_value) {
2431 const size_t regions = n_regions();
2432 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2433 // try to spread out the starting points of the workers
2434 const size_t start_index = regions / worker_num * (size_t) worker;
2435
2436 // each worker will actually look at all regions
2437 for (size_t count = 0; count < regions; ++count) {
2438 const size_t index = (start_index + count) % regions;
2439 assert(0 <= index && index < regions, "sanity");
2440 HeapRegion* r = region_at(index);
2441 // we'll ignore "continues humongous" regions (we'll process them
2442 // when we come across their corresponding "start humongous"
2443 // region) and regions already claimed
2444 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2445 continue;
2446 }
2447 // OK, try to claim it
2448 if (r->claimHeapRegion(claim_value)) {
2449 // success!
2450 assert(!r->continuesHumongous(), "sanity");
2451 if (r->startsHumongous()) {
2452 // If the region is "starts humongous" we'll iterate over its
2453 // "continues humongous" first; in fact we'll do them
2454 // first. The order is important. In on case, calling the
2455 // closure on the "starts humongous" region might de-allocate
2456 // and clear all its "continues humongous" regions and, as a
2457 // result, we might end up processing them twice. So, we'll do
2458 // them first (notice: most closures will ignore them anyway) and
2459 // then we'll do the "starts humongous" region.
2460 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2461 HeapRegion* chr = region_at(ch_index);
2462
2463 // if the region has already been claimed or it's not
2464 // "continues humongous" we're done
2465 if (chr->claim_value() == claim_value ||
2466 !chr->continuesHumongous()) {
2467 break;
2468 }
2469
2470 // Noone should have claimed it directly. We can given
2471 // that we claimed its "starts humongous" region.
2472 assert(chr->claim_value() != claim_value, "sanity");
2473 assert(chr->humongous_start_region() == r, "sanity");
2474
2475 if (chr->claimHeapRegion(claim_value)) {
2476 // we should always be able to claim it; noone else should
2477 // be trying to claim this region
2478
2479 bool res2 = cl->doHeapRegion(chr);
2480 assert(!res2, "Should not abort");
2481
2482 // Right now, this holds (i.e., no closure that actually
2483 // does something with "continues humongous" regions
2484 // clears them). We might have to weaken it in the future,
2485 // but let's leave these two asserts here for extra safety.
2486 assert(chr->continuesHumongous(), "should still be the case");
2487 assert(chr->humongous_start_region() == r, "sanity");
2488 } else {
2489 guarantee(false, "we should not reach here");
2490 }
2491 }
2492 }
2493
2494 assert(!r->continuesHumongous(), "sanity");
2495 bool res = cl->doHeapRegion(r);
2496 assert(!res, "Should not abort");
2497 }
2498 }
2499 }
2500
2501 class ResetClaimValuesClosure: public HeapRegionClosure {
2502 public:
2503 bool doHeapRegion(HeapRegion* r) {
2504 r->set_claim_value(HeapRegion::InitialClaimValue);
2505 return false;
2506 }
2507 };
2508
2509 void
2510 G1CollectedHeap::reset_heap_region_claim_values() {
2511 ResetClaimValuesClosure blk;
2512 heap_region_iterate(&blk);
2513 }
2514
2515 #ifdef ASSERT
2516 // This checks whether all regions in the heap have the correct claim
2517 // value. I also piggy-backed on this a check to ensure that the
2518 // humongous_start_region() information on "continues humongous"
2519 // regions is correct.
2520
2521 class CheckClaimValuesClosure : public HeapRegionClosure {
2522 private:
2523 jint _claim_value;
2524 size_t _failures;
2525 HeapRegion* _sh_region;
2526 public:
2527 CheckClaimValuesClosure(jint claim_value) :
2528 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2529 bool doHeapRegion(HeapRegion* r) {
2530 if (r->claim_value() != _claim_value) {
2531 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2532 "claim value = %d, should be %d",
2533 r->bottom(), r->end(), r->claim_value(),
2534 _claim_value);
2535 ++_failures;
2536 }
2537 if (!r->isHumongous()) {
2538 _sh_region = NULL;
2539 } else if (r->startsHumongous()) {
2540 _sh_region = r;
2541 } else if (r->continuesHumongous()) {
2542 if (r->humongous_start_region() != _sh_region) {
2543 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2544 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2545 r->bottom(), r->end(),
2546 r->humongous_start_region(),
2547 _sh_region);
2548 ++_failures;
2549 }
2550 }
2551 return false;
2552 }
2553 size_t failures() {
2554 return _failures;
2555 }
2556 };
2557
2558 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2559 CheckClaimValuesClosure cl(claim_value);
2560 heap_region_iterate(&cl);
2561 return cl.failures() == 0;
2562 }
2563 #endif // ASSERT
2564
2565 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2566 HeapRegion* r = g1_policy()->collection_set();
2567 while (r != NULL) {
2568 HeapRegion* next = r->next_in_collection_set();
2569 if (cl->doHeapRegion(r)) {
2570 cl->incomplete();
2571 return;
2572 }
2573 r = next;
2574 }
2575 }
2576
2577 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2578 HeapRegionClosure *cl) {
2579 if (r == NULL) {
2580 // The CSet is empty so there's nothing to do.
2581 return;
2582 }
2583
2584 assert(r->in_collection_set(),
2585 "Start region must be a member of the collection set.");
2586 HeapRegion* cur = r;
2587 while (cur != NULL) {
2588 HeapRegion* next = cur->next_in_collection_set();
2589 if (cl->doHeapRegion(cur) && false) {
2590 cl->incomplete();
2591 return;
2592 }
2593 cur = next;
2594 }
2595 cur = g1_policy()->collection_set();
2596 while (cur != r) {
2597 HeapRegion* next = cur->next_in_collection_set();
2598 if (cl->doHeapRegion(cur) && false) {
2599 cl->incomplete();
2600 return;
2601 }
2602 cur = next;
2603 }
2604 }
2605
2606 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2607 return n_regions() > 0 ? region_at(0) : NULL;
2608 }
2609
2610
2611 Space* G1CollectedHeap::space_containing(const void* addr) const {
2612 Space* res = heap_region_containing(addr);
2613 if (res == NULL)
2614 res = perm_gen()->space_containing(addr);
2615 return res;
2616 }
2617
2618 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2619 Space* sp = space_containing(addr);
2620 if (sp != NULL) {
2621 return sp->block_start(addr);
2622 }
2623 return NULL;
2624 }
2625
2626 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2627 Space* sp = space_containing(addr);
2628 assert(sp != NULL, "block_size of address outside of heap");
2629 return sp->block_size(addr);
2630 }
2631
2632 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2633 Space* sp = space_containing(addr);
2634 return sp->block_is_obj(addr);
2635 }
2636
2637 bool G1CollectedHeap::supports_tlab_allocation() const {
2638 return true;
2639 }
2640
2641 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2642 return HeapRegion::GrainBytes;
2643 }
2644
2645 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2646 // Return the remaining space in the cur alloc region, but not less than
2647 // the min TLAB size.
2648
2649 // Also, this value can be at most the humongous object threshold,
2650 // since we can't allow tlabs to grow big enough to accomodate
2651 // humongous objects.
2652
2653 HeapRegion* hr = _mutator_alloc_region.get();
2654 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2655 if (hr == NULL) {
2656 return max_tlab_size;
2657 } else {
2658 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2659 }
2660 }
2661
2662 size_t G1CollectedHeap::max_capacity() const {
2663 return _g1_reserved.byte_size();
2664 }
2665
2666 jlong G1CollectedHeap::millis_since_last_gc() {
2667 // assert(false, "NYI");
2668 return 0;
2669 }
2670
2671 void G1CollectedHeap::prepare_for_verify() {
2672 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2673 ensure_parsability(false);
2674 }
2675 g1_rem_set()->prepare_for_verify();
2676 }
2677
2678 class VerifyLivenessOopClosure: public OopClosure {
2679 G1CollectedHeap* _g1h;
2680 VerifyOption _vo;
2681 public:
2682 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2683 _g1h(g1h), _vo(vo)
2684 { }
2685 void do_oop(narrowOop *p) { do_oop_work(p); }
2686 void do_oop( oop *p) { do_oop_work(p); }
2687
2688 template <class T> void do_oop_work(T *p) {
2689 oop obj = oopDesc::load_decode_heap_oop(p);
2690 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2691 "Dead object referenced by a not dead object");
2692 }
2693 };
2694
2695 class VerifyObjsInRegionClosure: public ObjectClosure {
2696 private:
2697 G1CollectedHeap* _g1h;
2698 size_t _live_bytes;
2699 HeapRegion *_hr;
2700 VerifyOption _vo;
2701 public:
2702 // _vo == UsePrevMarking -> use "prev" marking information,
2703 // _vo == UseNextMarking -> use "next" marking information,
2704 // _vo == UseMarkWord -> use mark word from object header.
2705 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2706 : _live_bytes(0), _hr(hr), _vo(vo) {
2707 _g1h = G1CollectedHeap::heap();
2708 }
2709 void do_object(oop o) {
2710 VerifyLivenessOopClosure isLive(_g1h, _vo);
2711 assert(o != NULL, "Huh?");
2712 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2713 // If the object is alive according to the mark word,
2714 // then verify that the marking information agrees.
2715 // Note we can't verify the contra-positive of the
2716 // above: if the object is dead (according to the mark
2717 // word), it may not be marked, or may have been marked
2718 // but has since became dead, or may have been allocated
2719 // since the last marking.
2720 if (_vo == VerifyOption_G1UseMarkWord) {
2721 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2722 }
2723
2724 o->oop_iterate(&isLive);
2725 if (!_hr->obj_allocated_since_prev_marking(o)) {
2726 size_t obj_size = o->size(); // Make sure we don't overflow
2727 _live_bytes += (obj_size * HeapWordSize);
2728 }
2729 }
2730 }
2731 size_t live_bytes() { return _live_bytes; }
2732 };
2733
2734 class PrintObjsInRegionClosure : public ObjectClosure {
2735 HeapRegion *_hr;
2736 G1CollectedHeap *_g1;
2737 public:
2738 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2739 _g1 = G1CollectedHeap::heap();
2740 };
2741
2742 void do_object(oop o) {
2743 if (o != NULL) {
2744 HeapWord *start = (HeapWord *) o;
2745 size_t word_sz = o->size();
2746 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2747 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2748 (void*) o, word_sz,
2749 _g1->isMarkedPrev(o),
2750 _g1->isMarkedNext(o),
2751 _hr->obj_allocated_since_prev_marking(o));
2752 HeapWord *end = start + word_sz;
2753 HeapWord *cur;
2754 int *val;
2755 for (cur = start; cur < end; cur++) {
2756 val = (int *) cur;
2757 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2758 }
2759 }
2760 }
2761 };
2762
2763 class VerifyRegionClosure: public HeapRegionClosure {
2764 private:
2765 bool _allow_dirty;
2766 bool _par;
2767 VerifyOption _vo;
2768 bool _failures;
2769 public:
2770 // _vo == UsePrevMarking -> use "prev" marking information,
2771 // _vo == UseNextMarking -> use "next" marking information,
2772 // _vo == UseMarkWord -> use mark word from object header.
2773 VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2774 : _allow_dirty(allow_dirty),
2775 _par(par),
2776 _vo(vo),
2777 _failures(false) {}
2778
2779 bool failures() {
2780 return _failures;
2781 }
2782
2783 bool doHeapRegion(HeapRegion* r) {
2784 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2785 "Should be unclaimed at verify points.");
2786 if (!r->continuesHumongous()) {
2787 bool failures = false;
2788 r->verify(_allow_dirty, _vo, &failures);
2789 if (failures) {
2790 _failures = true;
2791 } else {
2792 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2793 r->object_iterate(¬_dead_yet_cl);
2794 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2795 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2796 "max_live_bytes "SIZE_FORMAT" "
2797 "< calculated "SIZE_FORMAT,
2798 r->bottom(), r->end(),
2799 r->max_live_bytes(),
2800 not_dead_yet_cl.live_bytes());
2801 _failures = true;
2802 }
2803 }
2804 }
2805 return false; // stop the region iteration if we hit a failure
2806 }
2807 };
2808
2809 class VerifyRootsClosure: public OopsInGenClosure {
2810 private:
2811 G1CollectedHeap* _g1h;
2812 VerifyOption _vo;
2813 bool _failures;
2814 public:
2815 // _vo == UsePrevMarking -> use "prev" marking information,
2816 // _vo == UseNextMarking -> use "next" marking information,
2817 // _vo == UseMarkWord -> use mark word from object header.
2818 VerifyRootsClosure(VerifyOption vo) :
2819 _g1h(G1CollectedHeap::heap()),
2820 _vo(vo),
2821 _failures(false) { }
2822
2823 bool failures() { return _failures; }
2824
2825 template <class T> void do_oop_nv(T* p) {
2826 T heap_oop = oopDesc::load_heap_oop(p);
2827 if (!oopDesc::is_null(heap_oop)) {
2828 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2829 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2830 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2831 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2832 if (_vo == VerifyOption_G1UseMarkWord) {
2833 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2834 }
2835 obj->print_on(gclog_or_tty);
2836 _failures = true;
2837 }
2838 }
2839 }
2840
2841 void do_oop(oop* p) { do_oop_nv(p); }
2842 void do_oop(narrowOop* p) { do_oop_nv(p); }
2843 };
2844
2845 // This is the task used for parallel heap verification.
2846
2847 class G1ParVerifyTask: public AbstractGangTask {
2848 private:
2849 G1CollectedHeap* _g1h;
2850 bool _allow_dirty;
2851 VerifyOption _vo;
2852 bool _failures;
2853
2854 public:
2855 // _vo == UsePrevMarking -> use "prev" marking information,
2856 // _vo == UseNextMarking -> use "next" marking information,
2857 // _vo == UseMarkWord -> use mark word from object header.
2858 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
2859 AbstractGangTask("Parallel verify task"),
2860 _g1h(g1h),
2861 _allow_dirty(allow_dirty),
2862 _vo(vo),
2863 _failures(false) { }
2864
2865 bool failures() {
2866 return _failures;
2867 }
2868
2869 void work(int worker_i) {
2870 HandleMark hm;
2871 VerifyRegionClosure blk(_allow_dirty, true, _vo);
2872 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2873 HeapRegion::ParVerifyClaimValue);
2874 if (blk.failures()) {
2875 _failures = true;
2876 }
2877 }
2878 };
2879
2880 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2881 verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
2882 }
2883
2884 void G1CollectedHeap::verify(bool allow_dirty,
2885 bool silent,
2886 VerifyOption vo) {
2887 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2888 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
2889 VerifyRootsClosure rootsCl(vo);
2890 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2891
2892 // We apply the relevant closures to all the oops in the
2893 // system dictionary, the string table and the code cache.
2894 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
2895
2896 process_strong_roots(true, // activate StrongRootsScope
2897 true, // we set "collecting perm gen" to true,
2898 // so we don't reset the dirty cards in the perm gen.
2899 SharedHeap::ScanningOption(so), // roots scanning options
2900 &rootsCl,
2901 &blobsCl,
2902 &rootsCl);
2903
2904 // If we're verifying after the marking phase of a Full GC then we can't
2905 // treat the perm gen as roots into the G1 heap. Some of the objects in
2906 // the perm gen may be dead and hence not marked. If one of these dead
2907 // objects is considered to be a root then we may end up with a false
2908 // "Root location <x> points to dead ob <y>" failure.
2909 if (vo != VerifyOption_G1UseMarkWord) {
2910 // Since we used "collecting_perm_gen" == true above, we will not have
2911 // checked the refs from perm into the G1-collected heap. We check those
2912 // references explicitly below. Whether the relevant cards are dirty
2913 // is checked further below in the rem set verification.
2914 if (!silent) { gclog_or_tty->print("Permgen roots "); }
2915 perm_gen()->oop_iterate(&rootsCl);
2916 }
2917 bool failures = rootsCl.failures();
2918
2919 if (vo != VerifyOption_G1UseMarkWord) {
2920 // If we're verifying during a full GC then the region sets
2921 // will have been torn down at the start of the GC. Therefore
2922 // verifying the region sets will fail. So we only verify
2923 // the region sets when not in a full GC.
2924 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
2925 verify_region_sets();
2926 }
2927
2928 if (!silent) { gclog_or_tty->print("HeapRegions "); }
2929 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2930 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2931 "sanity check");
2932
2933 G1ParVerifyTask task(this, allow_dirty, vo);
2934 int n_workers = workers()->total_workers();
2935 set_par_threads(n_workers);
2936 workers()->run_task(&task);
2937 set_par_threads(0);
2938 if (task.failures()) {
2939 failures = true;
2940 }
2941
2942 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2943 "sanity check");
2944
2945 reset_heap_region_claim_values();
2946
2947 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2948 "sanity check");
2949 } else {
2950 VerifyRegionClosure blk(allow_dirty, false, vo);
2951 heap_region_iterate(&blk);
2952 if (blk.failures()) {
2953 failures = true;
2954 }
2955 }
2956 if (!silent) gclog_or_tty->print("RemSet ");
2957 rem_set()->verify();
2958
2959 if (failures) {
2960 gclog_or_tty->print_cr("Heap:");
2961 print_on(gclog_or_tty, true /* extended */);
2962 gclog_or_tty->print_cr("");
2963 #ifndef PRODUCT
2964 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2965 concurrent_mark()->print_reachable("at-verification-failure",
2966 vo, false /* all */);
2967 }
2968 #endif
2969 gclog_or_tty->flush();
2970 }
2971 guarantee(!failures, "there should not have been any failures");
2972 } else {
2973 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2974 }
2975 }
2976
2977 class PrintRegionClosure: public HeapRegionClosure {
2978 outputStream* _st;
2979 public:
2980 PrintRegionClosure(outputStream* st) : _st(st) {}
2981 bool doHeapRegion(HeapRegion* r) {
2982 r->print_on(_st);
2983 return false;
2984 }
2985 };
2986
2987 void G1CollectedHeap::print() const { print_on(tty); }
2988
2989 void G1CollectedHeap::print_on(outputStream* st) const {
2990 print_on(st, PrintHeapAtGCExtended);
2991 }
2992
2993 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2994 st->print(" %-20s", "garbage-first heap");
2995 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2996 capacity()/K, used_unlocked()/K);
2997 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2998 _g1_storage.low_boundary(),
2999 _g1_storage.high(),
3000 _g1_storage.high_boundary());
3001 st->cr();
3002 st->print(" region size " SIZE_FORMAT "K, ",
3003 HeapRegion::GrainBytes/K);
3004 size_t young_regions = _young_list->length();
3005 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3006 young_regions, young_regions * HeapRegion::GrainBytes / K);
3007 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3008 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3009 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3010 st->cr();
3011 perm()->as_gen()->print_on(st);
3012 if (extended) {
3013 st->cr();
3014 print_on_extended(st);
3015 }
3016 }
3017
3018 void G1CollectedHeap::print_on_extended(outputStream* st) const {
3019 PrintRegionClosure blk(st);
3020 heap_region_iterate(&blk);
3021 }
3022
3023 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3024 if (G1CollectedHeap::use_parallel_gc_threads()) {
3025 workers()->print_worker_threads_on(st);
3026 }
3027 _cmThread->print_on(st);
3028 st->cr();
3029 _cm->print_worker_threads_on(st);
3030 _cg1r->print_worker_threads_on(st);
3031 st->cr();
3032 }
3033
3034 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3035 if (G1CollectedHeap::use_parallel_gc_threads()) {
3036 workers()->threads_do(tc);
3037 }
3038 tc->do_thread(_cmThread);
3039 _cg1r->threads_do(tc);
3040 }
3041
3042 void G1CollectedHeap::print_tracing_info() const {
3043 // We'll overload this to mean "trace GC pause statistics."
3044 if (TraceGen0Time || TraceGen1Time) {
3045 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3046 // to that.
3047 g1_policy()->print_tracing_info();
3048 }
3049 if (G1SummarizeRSetStats) {
3050 g1_rem_set()->print_summary_info();
3051 }
3052 if (G1SummarizeConcMark) {
3053 concurrent_mark()->print_summary_info();
3054 }
3055 g1_policy()->print_yg_surv_rate_info();
3056 SpecializationStats::print();
3057 }
3058
3059 #ifndef PRODUCT
3060 // Helpful for debugging RSet issues.
3061
3062 class PrintRSetsClosure : public HeapRegionClosure {
3063 private:
3064 const char* _msg;
3065 size_t _occupied_sum;
3066
3067 public:
3068 bool doHeapRegion(HeapRegion* r) {
3069 HeapRegionRemSet* hrrs = r->rem_set();
3070 size_t occupied = hrrs->occupied();
3071 _occupied_sum += occupied;
3072
3073 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3074 HR_FORMAT_PARAMS(r));
3075 if (occupied == 0) {
3076 gclog_or_tty->print_cr(" RSet is empty");
3077 } else {
3078 hrrs->print();
3079 }
3080 gclog_or_tty->print_cr("----------");
3081 return false;
3082 }
3083
3084 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3085 gclog_or_tty->cr();
3086 gclog_or_tty->print_cr("========================================");
3087 gclog_or_tty->print_cr(msg);
3088 gclog_or_tty->cr();
3089 }
3090
3091 ~PrintRSetsClosure() {
3092 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3093 gclog_or_tty->print_cr("========================================");
3094 gclog_or_tty->cr();
3095 }
3096 };
3097
3098 void G1CollectedHeap::print_cset_rsets() {
3099 PrintRSetsClosure cl("Printing CSet RSets");
3100 collection_set_iterate(&cl);
3101 }
3102
3103 void G1CollectedHeap::print_all_rsets() {
3104 PrintRSetsClosure cl("Printing All RSets");;
3105 heap_region_iterate(&cl);
3106 }
3107 #endif // PRODUCT
3108
3109 G1CollectedHeap* G1CollectedHeap::heap() {
3110 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3111 "not a garbage-first heap");
3112 return _g1h;
3113 }
3114
3115 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3116 // always_do_update_barrier = false;
3117 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3118 // Call allocation profiler
3119 AllocationProfiler::iterate_since_last_gc();
3120 // Fill TLAB's and such
3121 ensure_parsability(true);
3122 }
3123
3124 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3125 // FIXME: what is this about?
3126 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3127 // is set.
3128 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3129 "derived pointer present"));
3130 // always_do_update_barrier = true;
3131 }
3132
3133 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3134 unsigned int gc_count_before,
3135 bool* succeeded) {
3136 assert_heap_not_locked_and_not_at_safepoint();
3137 g1_policy()->record_stop_world_start();
3138 VM_G1IncCollectionPause op(gc_count_before,
3139 word_size,
3140 false, /* should_initiate_conc_mark */
3141 g1_policy()->max_pause_time_ms(),
3142 GCCause::_g1_inc_collection_pause);
3143 VMThread::execute(&op);
3144
3145 HeapWord* result = op.result();
3146 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3147 assert(result == NULL || ret_succeeded,
3148 "the result should be NULL if the VM did not succeed");
3149 *succeeded = ret_succeeded;
3150
3151 assert_heap_not_locked();
3152 return result;
3153 }
3154
3155 void
3156 G1CollectedHeap::doConcurrentMark() {
3157 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3158 if (!_cmThread->in_progress()) {
3159 _cmThread->set_started();
3160 CGC_lock->notify();
3161 }
3162 }
3163
3164 void G1CollectedHeap::do_sync_mark() {
3165 _cm->checkpointRootsInitial();
3166 _cm->markFromRoots();
3167 _cm->checkpointRootsFinal(false);
3168 }
3169
3170 // <NEW PREDICTION>
3171
3172 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3173 bool young) {
3174 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3175 }
3176
3177 void G1CollectedHeap::check_if_region_is_too_expensive(double
3178 predicted_time_ms) {
3179 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3180 }
3181
3182 size_t G1CollectedHeap::pending_card_num() {
3183 size_t extra_cards = 0;
3184 JavaThread *curr = Threads::first();
3185 while (curr != NULL) {
3186 DirtyCardQueue& dcq = curr->dirty_card_queue();
3187 extra_cards += dcq.size();
3188 curr = curr->next();
3189 }
3190 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3191 size_t buffer_size = dcqs.buffer_size();
3192 size_t buffer_num = dcqs.completed_buffers_num();
3193 return buffer_size * buffer_num + extra_cards;
3194 }
3195
3196 size_t G1CollectedHeap::max_pending_card_num() {
3197 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3198 size_t buffer_size = dcqs.buffer_size();
3199 size_t buffer_num = dcqs.completed_buffers_num();
3200 int thread_num = Threads::number_of_threads();
3201 return (buffer_num + thread_num) * buffer_size;
3202 }
3203
3204 size_t G1CollectedHeap::cards_scanned() {
3205 return g1_rem_set()->cardsScanned();
3206 }
3207
3208 void
3209 G1CollectedHeap::setup_surviving_young_words() {
3210 guarantee( _surviving_young_words == NULL, "pre-condition" );
3211 size_t array_length = g1_policy()->young_cset_length();
3212 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3213 if (_surviving_young_words == NULL) {
3214 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3215 "Not enough space for young surv words summary.");
3216 }
3217 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3218 #ifdef ASSERT
3219 for (size_t i = 0; i < array_length; ++i) {
3220 assert( _surviving_young_words[i] == 0, "memset above" );
3221 }
3222 #endif // !ASSERT
3223 }
3224
3225 void
3226 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3227 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3228 size_t array_length = g1_policy()->young_cset_length();
3229 for (size_t i = 0; i < array_length; ++i)
3230 _surviving_young_words[i] += surv_young_words[i];
3231 }
3232
3233 void
3234 G1CollectedHeap::cleanup_surviving_young_words() {
3235 guarantee( _surviving_young_words != NULL, "pre-condition" );
3236 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3237 _surviving_young_words = NULL;
3238 }
3239
3240 // </NEW PREDICTION>
3241
3242 #ifdef ASSERT
3243 class VerifyCSetClosure: public HeapRegionClosure {
3244 public:
3245 bool doHeapRegion(HeapRegion* hr) {
3246 // Here we check that the CSet region's RSet is ready for parallel
3247 // iteration. The fields that we'll verify are only manipulated
3248 // when the region is part of a CSet and is collected. Afterwards,
3249 // we reset these fields when we clear the region's RSet (when the
3250 // region is freed) so they are ready when the region is
3251 // re-allocated. The only exception to this is if there's an
3252 // evacuation failure and instead of freeing the region we leave
3253 // it in the heap. In that case, we reset these fields during
3254 // evacuation failure handling.
3255 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3256
3257 // Here's a good place to add any other checks we'd like to
3258 // perform on CSet regions.
3259 return false;
3260 }
3261 };
3262 #endif // ASSERT
3263
3264 #if TASKQUEUE_STATS
3265 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3266 st->print_raw_cr("GC Task Stats");
3267 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3268 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3269 }
3270
3271 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3272 print_taskqueue_stats_hdr(st);
3273
3274 TaskQueueStats totals;
3275 const int n = workers() != NULL ? workers()->total_workers() : 1;
3276 for (int i = 0; i < n; ++i) {
3277 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3278 totals += task_queue(i)->stats;
3279 }
3280 st->print_raw("tot "); totals.print(st); st->cr();
3281
3282 DEBUG_ONLY(totals.verify());
3283 }
3284
3285 void G1CollectedHeap::reset_taskqueue_stats() {
3286 const int n = workers() != NULL ? workers()->total_workers() : 1;
3287 for (int i = 0; i < n; ++i) {
3288 task_queue(i)->stats.reset();
3289 }
3290 }
3291 #endif // TASKQUEUE_STATS
3292
3293 bool
3294 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3295 assert_at_safepoint(true /* should_be_vm_thread */);
3296 guarantee(!is_gc_active(), "collection is not reentrant");
3297
3298 if (GC_locker::check_active_before_gc()) {
3299 return false;
3300 }
3301
3302 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3303 ResourceMark rm;
3304
3305 if (PrintHeapAtGC) {
3306 Universe::print_heap_before_gc();
3307 }
3308
3309 verify_region_sets_optional();
3310 verify_dirty_young_regions();
3311
3312 {
3313 // This call will decide whether this pause is an initial-mark
3314 // pause. If it is, during_initial_mark_pause() will return true
3315 // for the duration of this pause.
3316 g1_policy()->decide_on_conc_mark_initiation();
3317
3318 char verbose_str[128];
3319 sprintf(verbose_str, "GC pause ");
3320 if (g1_policy()->in_young_gc_mode()) {
3321 if (g1_policy()->full_young_gcs())
3322 strcat(verbose_str, "(young)");
3323 else
3324 strcat(verbose_str, "(partial)");
3325 }
3326 if (g1_policy()->during_initial_mark_pause()) {
3327 strcat(verbose_str, " (initial-mark)");
3328 // We are about to start a marking cycle, so we increment the
3329 // full collection counter.
3330 increment_total_full_collections();
3331 }
3332
3333 // if PrintGCDetails is on, we'll print long statistics information
3334 // in the collector policy code, so let's not print this as the output
3335 // is messy if we do.
3336 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3337 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3338 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3339
3340 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3341 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3342
3343 // If the secondary_free_list is not empty, append it to the
3344 // free_list. No need to wait for the cleanup operation to finish;
3345 // the region allocation code will check the secondary_free_list
3346 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3347 // set, skip this step so that the region allocation code has to
3348 // get entries from the secondary_free_list.
3349 if (!G1StressConcRegionFreeing) {
3350 append_secondary_free_list_if_not_empty_with_lock();
3351 }
3352
3353 if (g1_policy()->in_young_gc_mode()) {
3354 assert(check_young_list_well_formed(),
3355 "young list should be well formed");
3356 }
3357
3358 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3359 IsGCActiveMark x;
3360
3361 gc_prologue(false);
3362 increment_total_collections(false /* full gc */);
3363 increment_gc_time_stamp();
3364
3365 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3366 HandleMark hm; // Discard invalid handles created during verification
3367 gclog_or_tty->print(" VerifyBeforeGC:");
3368 prepare_for_verify();
3369 Universe::verify(/* allow dirty */ false,
3370 /* silent */ false,
3371 /* option */ VerifyOption_G1UsePrevMarking);
3372
3373 }
3374
3375 COMPILER2_PRESENT(DerivedPointerTable::clear());
3376
3377 // Please see comment in G1CollectedHeap::ref_processing_init()
3378 // to see how reference processing currently works in G1.
3379 //
3380 // We want to turn off ref discovery, if necessary, and turn it back on
3381 // on again later if we do. XXX Dubious: why is discovery disabled?
3382 bool was_enabled = ref_processor()->discovery_enabled();
3383 if (was_enabled) ref_processor()->disable_discovery();
3384
3385 // Forget the current alloc region (we might even choose it to be part
3386 // of the collection set!).
3387 release_mutator_alloc_region();
3388
3389 // We should call this after we retire the mutator alloc
3390 // region(s) so that all the ALLOC / RETIRE events are generated
3391 // before the start GC event.
3392 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3393
3394 // The elapsed time induced by the start time below deliberately elides
3395 // the possible verification above.
3396 double start_time_sec = os::elapsedTime();
3397 size_t start_used_bytes = used();
3398
3399 #if YOUNG_LIST_VERBOSE
3400 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3401 _young_list->print();
3402 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3403 #endif // YOUNG_LIST_VERBOSE
3404
3405 g1_policy()->record_collection_pause_start(start_time_sec,
3406 start_used_bytes);
3407
3408 #if YOUNG_LIST_VERBOSE
3409 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3410 _young_list->print();
3411 #endif // YOUNG_LIST_VERBOSE
3412
3413 if (g1_policy()->during_initial_mark_pause()) {
3414 concurrent_mark()->checkpointRootsInitialPre();
3415 }
3416 perm_gen()->save_marks();
3417
3418 // We must do this before any possible evacuation that should propagate
3419 // marks.
3420 if (mark_in_progress()) {
3421 double start_time_sec = os::elapsedTime();
3422
3423 _cm->drainAllSATBBuffers();
3424 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3425 g1_policy()->record_satb_drain_time(finish_mark_ms);
3426 }
3427 // Record the number of elements currently on the mark stack, so we
3428 // only iterate over these. (Since evacuation may add to the mark
3429 // stack, doing more exposes race conditions.) If no mark is in
3430 // progress, this will be zero.
3431 _cm->set_oops_do_bound();
3432
3433 if (mark_in_progress()) {
3434 concurrent_mark()->newCSet();
3435 }
3436
3437 #if YOUNG_LIST_VERBOSE
3438 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3439 _young_list->print();
3440 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3441 #endif // YOUNG_LIST_VERBOSE
3442
3443 g1_policy()->choose_collection_set(target_pause_time_ms);
3444
3445 if (_hr_printer.is_active()) {
3446 HeapRegion* hr = g1_policy()->collection_set();
3447 while (hr != NULL) {
3448 G1HRPrinter::RegionType type;
3449 if (!hr->is_young()) {
3450 type = G1HRPrinter::Old;
3451 } else if (hr->is_survivor()) {
3452 type = G1HRPrinter::Survivor;
3453 } else {
3454 type = G1HRPrinter::Eden;
3455 }
3456 _hr_printer.cset(hr);
3457 hr = hr->next_in_collection_set();
3458 }
3459 }
3460
3461 // We have chosen the complete collection set. If marking is
3462 // active then, we clear the region fields of any of the
3463 // concurrent marking tasks whose region fields point into
3464 // the collection set as these values will become stale. This
3465 // will cause the owning marking threads to claim a new region
3466 // when marking restarts.
3467 if (mark_in_progress()) {
3468 concurrent_mark()->reset_active_task_region_fields_in_cset();
3469 }
3470
3471 #ifdef ASSERT
3472 VerifyCSetClosure cl;
3473 collection_set_iterate(&cl);
3474 #endif // ASSERT
3475
3476 setup_surviving_young_words();
3477
3478 // Initialize the GC alloc regions.
3479 init_gc_alloc_regions();
3480
3481 // Actually do the work...
3482 evacuate_collection_set();
3483
3484 free_collection_set(g1_policy()->collection_set());
3485 g1_policy()->clear_collection_set();
3486
3487 cleanup_surviving_young_words();
3488
3489 // Start a new incremental collection set for the next pause.
3490 g1_policy()->start_incremental_cset_building();
3491
3492 // Clear the _cset_fast_test bitmap in anticipation of adding
3493 // regions to the incremental collection set for the next
3494 // evacuation pause.
3495 clear_cset_fast_test();
3496
3497 if (g1_policy()->in_young_gc_mode()) {
3498 _young_list->reset_sampled_info();
3499
3500 // Don't check the whole heap at this point as the
3501 // GC alloc regions from this pause have been tagged
3502 // as survivors and moved on to the survivor list.
3503 // Survivor regions will fail the !is_young() check.
3504 assert(check_young_list_empty(false /* check_heap */),
3505 "young list should be empty");
3506
3507 #if YOUNG_LIST_VERBOSE
3508 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3509 _young_list->print();
3510 #endif // YOUNG_LIST_VERBOSE
3511
3512 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3513 _young_list->first_survivor_region(),
3514 _young_list->last_survivor_region());
3515
3516 _young_list->reset_auxilary_lists();
3517 }
3518
3519 if (evacuation_failed()) {
3520 _summary_bytes_used = recalculate_used();
3521 } else {
3522 // The "used" of the the collection set have already been subtracted
3523 // when they were freed. Add in the bytes evacuated.
3524 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3525 }
3526
3527 if (g1_policy()->in_young_gc_mode() &&
3528 g1_policy()->during_initial_mark_pause()) {
3529 concurrent_mark()->checkpointRootsInitialPost();
3530 set_marking_started();
3531 // CAUTION: after the doConcurrentMark() call below,
3532 // the concurrent marking thread(s) could be running
3533 // concurrently with us. Make sure that anything after
3534 // this point does not assume that we are the only GC thread
3535 // running. Note: of course, the actual marking work will
3536 // not start until the safepoint itself is released in
3537 // ConcurrentGCThread::safepoint_desynchronize().
3538 doConcurrentMark();
3539 }
3540
3541 allocate_dummy_regions();
3542
3543 #if YOUNG_LIST_VERBOSE
3544 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3545 _young_list->print();
3546 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3547 #endif // YOUNG_LIST_VERBOSE
3548
3549 init_mutator_alloc_region();
3550
3551 double end_time_sec = os::elapsedTime();
3552 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3553 g1_policy()->record_pause_time_ms(pause_time_ms);
3554 g1_policy()->record_collection_pause_end();
3555
3556 MemoryService::track_memory_usage();
3557
3558 // In prepare_for_verify() below we'll need to scan the deferred
3559 // update buffers to bring the RSets up-to-date if
3560 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3561 // the update buffers we'll probably need to scan cards on the
3562 // regions we just allocated to (i.e., the GC alloc
3563 // regions). However, during the last GC we called
3564 // set_saved_mark() on all the GC alloc regions, so card
3565 // scanning might skip the [saved_mark_word()...top()] area of
3566 // those regions (i.e., the area we allocated objects into
3567 // during the last GC). But it shouldn't. Given that
3568 // saved_mark_word() is conditional on whether the GC time stamp
3569 // on the region is current or not, by incrementing the GC time
3570 // stamp here we invalidate all the GC time stamps on all the
3571 // regions and saved_mark_word() will simply return top() for
3572 // all the regions. This is a nicer way of ensuring this rather
3573 // than iterating over the regions and fixing them. In fact, the
3574 // GC time stamp increment here also ensures that
3575 // saved_mark_word() will return top() between pauses, i.e.,
3576 // during concurrent refinement. So we don't need the
3577 // is_gc_active() check to decided which top to use when
3578 // scanning cards (see CR 7039627).
3579 increment_gc_time_stamp();
3580
3581 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3582 HandleMark hm; // Discard invalid handles created during verification
3583 gclog_or_tty->print(" VerifyAfterGC:");
3584 prepare_for_verify();
3585 Universe::verify(/* allow dirty */ true,
3586 /* silent */ false,
3587 /* option */ VerifyOption_G1UsePrevMarking);
3588 }
3589
3590 if (was_enabled) ref_processor()->enable_discovery();
3591
3592 {
3593 size_t expand_bytes = g1_policy()->expansion_amount();
3594 if (expand_bytes > 0) {
3595 size_t bytes_before = capacity();
3596 if (!expand(expand_bytes)) {
3597 // We failed to expand the heap so let's verify that
3598 // committed/uncommitted amount match the backing store
3599 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3600 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3601 }
3602 }
3603 }
3604
3605 // We should do this after we potentially expand the heap so
3606 // that all the COMMIT events are generated before the end GC
3607 // event, and after we retire the GC alloc regions so that all
3608 // RETIRE events are generated before the end GC event.
3609 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3610
3611 // We have to do this after we decide whether to expand the heap or not.
3612 g1_policy()->print_heap_transition();
3613
3614 if (mark_in_progress()) {
3615 concurrent_mark()->update_g1_committed();
3616 }
3617
3618 #ifdef TRACESPINNING
3619 ParallelTaskTerminator::print_termination_counts();
3620 #endif
3621
3622 gc_epilogue(false);
3623 }
3624
3625 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3626 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3627 print_tracing_info();
3628 vm_exit(-1);
3629 }
3630 }
3631
3632 _hrs.verify_optional();
3633 verify_region_sets_optional();
3634
3635 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3636 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3637
3638 if (PrintHeapAtGC) {
3639 Universe::print_heap_after_gc();
3640 }
3641 g1mm()->update_counters();
3642
3643 if (G1SummarizeRSetStats &&
3644 (G1SummarizeRSetStatsPeriod > 0) &&
3645 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3646 g1_rem_set()->print_summary_info();
3647 }
3648
3649 return true;
3650 }
3651
3652 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3653 {
3654 size_t gclab_word_size;
3655 switch (purpose) {
3656 case GCAllocForSurvived:
3657 gclab_word_size = YoungPLABSize;
3658 break;
3659 case GCAllocForTenured:
3660 gclab_word_size = OldPLABSize;
3661 break;
3662 default:
3663 assert(false, "unknown GCAllocPurpose");
3664 gclab_word_size = OldPLABSize;
3665 break;
3666 }
3667 return gclab_word_size;
3668 }
3669
3670 void G1CollectedHeap::init_mutator_alloc_region() {
3671 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3672 _mutator_alloc_region.init();
3673 }
3674
3675 void G1CollectedHeap::release_mutator_alloc_region() {
3676 _mutator_alloc_region.release();
3677 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3678 }
3679
3680 void G1CollectedHeap::init_gc_alloc_regions() {
3681 assert_at_safepoint(true /* should_be_vm_thread */);
3682
3683 _survivor_gc_alloc_region.init();
3684 _old_gc_alloc_region.init();
3685 HeapRegion* retained_region = _retained_old_gc_alloc_region;
3686 _retained_old_gc_alloc_region = NULL;
3687
3688 // We will discard the current GC alloc region if:
3689 // a) it's in the collection set (it can happen!),
3690 // b) it's already full (no point in using it),
3691 // c) it's empty (this means that it was emptied during
3692 // a cleanup and it should be on the free list now), or
3693 // d) it's humongous (this means that it was emptied
3694 // during a cleanup and was added to the free list, but
3695 // has been subseqently used to allocate a humongous
3696 // object that may be less than the region size).
3697 if (retained_region != NULL &&
3698 !retained_region->in_collection_set() &&
3699 !(retained_region->top() == retained_region->end()) &&
3700 !retained_region->is_empty() &&
3701 !retained_region->isHumongous()) {
3702 retained_region->set_saved_mark();
3703 _old_gc_alloc_region.set(retained_region);
3704 _hr_printer.reuse(retained_region);
3705 }
3706 }
3707
3708 void G1CollectedHeap::release_gc_alloc_regions() {
3709 _survivor_gc_alloc_region.release();
3710 // If we have an old GC alloc region to release, we'll save it in
3711 // _retained_old_gc_alloc_region. If we don't
3712 // _retained_old_gc_alloc_region will become NULL. This is what we
3713 // want either way so no reason to check explicitly for either
3714 // condition.
3715 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3716 }
3717
3718 void G1CollectedHeap::abandon_gc_alloc_regions() {
3719 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3720 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3721 _retained_old_gc_alloc_region = NULL;
3722 }
3723
3724 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3725 _drain_in_progress = false;
3726 set_evac_failure_closure(cl);
3727 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3728 }
3729
3730 void G1CollectedHeap::finalize_for_evac_failure() {
3731 assert(_evac_failure_scan_stack != NULL &&
3732 _evac_failure_scan_stack->length() == 0,
3733 "Postcondition");
3734 assert(!_drain_in_progress, "Postcondition");
3735 delete _evac_failure_scan_stack;
3736 _evac_failure_scan_stack = NULL;
3737 }
3738
3739 // *** Sequential G1 Evacuation
3740
3741 class G1IsAliveClosure: public BoolObjectClosure {
3742 G1CollectedHeap* _g1;
3743 public:
3744 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3745 void do_object(oop p) { assert(false, "Do not call."); }
3746 bool do_object_b(oop p) {
3747 // It is reachable if it is outside the collection set, or is inside
3748 // and forwarded.
3749
3750 #ifdef G1_DEBUG
3751 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3752 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3753 !_g1->obj_in_cs(p) || p->is_forwarded());
3754 #endif // G1_DEBUG
3755
3756 return !_g1->obj_in_cs(p) || p->is_forwarded();
3757 }
3758 };
3759
3760 class G1KeepAliveClosure: public OopClosure {
3761 G1CollectedHeap* _g1;
3762 public:
3763 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3764 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3765 void do_oop( oop* p) {
3766 oop obj = *p;
3767 #ifdef G1_DEBUG
3768 if (PrintGC && Verbose) {
3769 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3770 p, (void*) obj, (void*) *p);
3771 }
3772 #endif // G1_DEBUG
3773
3774 if (_g1->obj_in_cs(obj)) {
3775 assert( obj->is_forwarded(), "invariant" );
3776 *p = obj->forwardee();
3777 #ifdef G1_DEBUG
3778 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3779 (void*) obj, (void*) *p);
3780 #endif // G1_DEBUG
3781 }
3782 }
3783 };
3784
3785 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3786 private:
3787 G1CollectedHeap* _g1;
3788 DirtyCardQueue *_dcq;
3789 CardTableModRefBS* _ct_bs;
3790
3791 public:
3792 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3793 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3794
3795 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3796 virtual void do_oop( oop* p) { do_oop_work(p); }
3797 template <class T> void do_oop_work(T* p) {
3798 assert(_from->is_in_reserved(p), "paranoia");
3799 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3800 !_from->is_survivor()) {
3801 size_t card_index = _ct_bs->index_for(p);
3802 if (_ct_bs->mark_card_deferred(card_index)) {
3803 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3804 }
3805 }
3806 }
3807 };
3808
3809 class RemoveSelfPointerClosure: public ObjectClosure {
3810 private:
3811 G1CollectedHeap* _g1;
3812 ConcurrentMark* _cm;
3813 HeapRegion* _hr;
3814 size_t _prev_marked_bytes;
3815 size_t _next_marked_bytes;
3816 OopsInHeapRegionClosure *_cl;
3817 public:
3818 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
3819 OopsInHeapRegionClosure* cl) :
3820 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3821 _next_marked_bytes(0), _cl(cl) {}
3822
3823 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3824 size_t next_marked_bytes() { return _next_marked_bytes; }
3825
3826 // <original comment>
3827 // The original idea here was to coalesce evacuated and dead objects.
3828 // However that caused complications with the block offset table (BOT).
3829 // In particular if there were two TLABs, one of them partially refined.
3830 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3831 // The BOT entries of the unrefined part of TLAB_2 point to the start
3832 // of TLAB_2. If the last object of the TLAB_1 and the first object
3833 // of TLAB_2 are coalesced, then the cards of the unrefined part
3834 // would point into middle of the filler object.
3835 // The current approach is to not coalesce and leave the BOT contents intact.
3836 // </original comment>
3837 //
3838 // We now reset the BOT when we start the object iteration over the
3839 // region and refine its entries for every object we come across. So
3840 // the above comment is not really relevant and we should be able
3841 // to coalesce dead objects if we want to.
3842 void do_object(oop obj) {
3843 HeapWord* obj_addr = (HeapWord*) obj;
3844 assert(_hr->is_in(obj_addr), "sanity");
3845 size_t obj_size = obj->size();
3846 _hr->update_bot_for_object(obj_addr, obj_size);
3847 if (obj->is_forwarded() && obj->forwardee() == obj) {
3848 // The object failed to move.
3849 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3850 _cm->markPrev(obj);
3851 assert(_cm->isPrevMarked(obj), "Should be marked!");
3852 _prev_marked_bytes += (obj_size * HeapWordSize);
3853 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3854 _cm->markAndGrayObjectIfNecessary(obj);
3855 }
3856 obj->set_mark(markOopDesc::prototype());
3857 // While we were processing RSet buffers during the
3858 // collection, we actually didn't scan any cards on the
3859 // collection set, since we didn't want to update remebered
3860 // sets with entries that point into the collection set, given
3861 // that live objects fromthe collection set are about to move
3862 // and such entries will be stale very soon. This change also
3863 // dealt with a reliability issue which involved scanning a
3864 // card in the collection set and coming across an array that
3865 // was being chunked and looking malformed. The problem is
3866 // that, if evacuation fails, we might have remembered set
3867 // entries missing given that we skipped cards on the
3868 // collection set. So, we'll recreate such entries now.
3869 obj->oop_iterate(_cl);
3870 assert(_cm->isPrevMarked(obj), "Should be marked!");
3871 } else {
3872 // The object has been either evacuated or is dead. Fill it with a
3873 // dummy object.
3874 MemRegion mr((HeapWord*)obj, obj_size);
3875 CollectedHeap::fill_with_object(mr);
3876 _cm->clearRangeBothMaps(mr);
3877 }
3878 }
3879 };
3880
3881 void G1CollectedHeap::remove_self_forwarding_pointers() {
3882 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3883 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3884 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3885 OopsInHeapRegionClosure *cl;
3886 if (G1DeferredRSUpdate) {
3887 cl = &deferred_update;
3888 } else {
3889 cl = &immediate_update;
3890 }
3891 HeapRegion* cur = g1_policy()->collection_set();
3892 while (cur != NULL) {
3893 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3894 assert(!cur->isHumongous(), "sanity");
3895
3896 if (cur->evacuation_failed()) {
3897 assert(cur->in_collection_set(), "bad CS");
3898 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
3899
3900 // In the common case we make sure that this is done when the
3901 // region is freed so that it is "ready-to-go" when it's
3902 // re-allocated. However, when evacuation failure happens, a
3903 // region will remain in the heap and might ultimately be added
3904 // to a CSet in the future. So we have to be careful here and
3905 // make sure the region's RSet is ready for parallel iteration
3906 // whenever this might be required in the future.
3907 cur->rem_set()->reset_for_par_iteration();
3908 cur->reset_bot();
3909 cl->set_region(cur);
3910 cur->object_iterate(&rspc);
3911
3912 // A number of manipulations to make the TAMS be the current top,
3913 // and the marked bytes be the ones observed in the iteration.
3914 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3915 // The comments below are the postconditions achieved by the
3916 // calls. Note especially the last such condition, which says that
3917 // the count of marked bytes has been properly restored.
3918 cur->note_start_of_marking(false);
3919 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3920 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3921 // _next_marked_bytes == prev_marked_bytes.
3922 cur->note_end_of_marking();
3923 // _prev_top_at_mark_start == top(),
3924 // _prev_marked_bytes == prev_marked_bytes
3925 }
3926 // If there is no mark in progress, we modified the _next variables
3927 // above needlessly, but harmlessly.
3928 if (_g1h->mark_in_progress()) {
3929 cur->note_start_of_marking(false);
3930 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3931 // _next_marked_bytes == next_marked_bytes.
3932 }
3933
3934 // Now make sure the region has the right index in the sorted array.
3935 g1_policy()->note_change_in_marked_bytes(cur);
3936 }
3937 cur = cur->next_in_collection_set();
3938 }
3939 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3940
3941 // Now restore saved marks, if any.
3942 if (_objs_with_preserved_marks != NULL) {
3943 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3944 guarantee(_objs_with_preserved_marks->length() ==
3945 _preserved_marks_of_objs->length(), "Both or none.");
3946 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3947 oop obj = _objs_with_preserved_marks->at(i);
3948 markOop m = _preserved_marks_of_objs->at(i);
3949 obj->set_mark(m);
3950 }
3951 // Delete the preserved marks growable arrays (allocated on the C heap).
3952 delete _objs_with_preserved_marks;
3953 delete _preserved_marks_of_objs;
3954 _objs_with_preserved_marks = NULL;
3955 _preserved_marks_of_objs = NULL;
3956 }
3957 }
3958
3959 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3960 _evac_failure_scan_stack->push(obj);
3961 }
3962
3963 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3964 assert(_evac_failure_scan_stack != NULL, "precondition");
3965
3966 while (_evac_failure_scan_stack->length() > 0) {
3967 oop obj = _evac_failure_scan_stack->pop();
3968 _evac_failure_closure->set_region(heap_region_containing(obj));
3969 obj->oop_iterate_backwards(_evac_failure_closure);
3970 }
3971 }
3972
3973 oop
3974 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3975 oop old) {
3976 assert(obj_in_cs(old),
3977 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
3978 (HeapWord*) old));
3979 markOop m = old->mark();
3980 oop forward_ptr = old->forward_to_atomic(old);
3981 if (forward_ptr == NULL) {
3982 // Forward-to-self succeeded.
3983 if (_evac_failure_closure != cl) {
3984 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3985 assert(!_drain_in_progress,
3986 "Should only be true while someone holds the lock.");
3987 // Set the global evac-failure closure to the current thread's.
3988 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3989 set_evac_failure_closure(cl);
3990 // Now do the common part.
3991 handle_evacuation_failure_common(old, m);
3992 // Reset to NULL.
3993 set_evac_failure_closure(NULL);
3994 } else {
3995 // The lock is already held, and this is recursive.
3996 assert(_drain_in_progress, "This should only be the recursive case.");
3997 handle_evacuation_failure_common(old, m);
3998 }
3999 return old;
4000 } else {
4001 // Forward-to-self failed. Either someone else managed to allocate
4002 // space for this object (old != forward_ptr) or they beat us in
4003 // self-forwarding it (old == forward_ptr).
4004 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4005 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4006 "should not be in the CSet",
4007 (HeapWord*) old, (HeapWord*) forward_ptr));
4008 return forward_ptr;
4009 }
4010 }
4011
4012 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4013 set_evacuation_failed(true);
4014
4015 preserve_mark_if_necessary(old, m);
4016
4017 HeapRegion* r = heap_region_containing(old);
4018 if (!r->evacuation_failed()) {
4019 r->set_evacuation_failed(true);
4020 _hr_printer.evac_failure(r);
4021 }
4022
4023 push_on_evac_failure_scan_stack(old);
4024
4025 if (!_drain_in_progress) {
4026 // prevent recursion in copy_to_survivor_space()
4027 _drain_in_progress = true;
4028 drain_evac_failure_scan_stack();
4029 _drain_in_progress = false;
4030 }
4031 }
4032
4033 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4034 assert(evacuation_failed(), "Oversaving!");
4035 // We want to call the "for_promotion_failure" version only in the
4036 // case of a promotion failure.
4037 if (m->must_be_preserved_for_promotion_failure(obj)) {
4038 if (_objs_with_preserved_marks == NULL) {
4039 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4040 _objs_with_preserved_marks =
4041 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4042 _preserved_marks_of_objs =
4043 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4044 }
4045 _objs_with_preserved_marks->push(obj);
4046 _preserved_marks_of_objs->push(m);
4047 }
4048 }
4049
4050 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4051 size_t word_size) {
4052 if (purpose == GCAllocForSurvived) {
4053 HeapWord* result = survivor_attempt_allocation(word_size);
4054 if (result != NULL) {
4055 return result;
4056 } else {
4057 // Let's try to allocate in the old gen in case we can fit the
4058 // object there.
4059 return old_attempt_allocation(word_size);
4060 }
4061 } else {
4062 assert(purpose == GCAllocForTenured, "sanity");
4063 HeapWord* result = old_attempt_allocation(word_size);
4064 if (result != NULL) {
4065 return result;
4066 } else {
4067 // Let's try to allocate in the survivors in case we can fit the
4068 // object there.
4069 return survivor_attempt_allocation(word_size);
4070 }
4071 }
4072
4073 ShouldNotReachHere();
4074 // Trying to keep some compilers happy.
4075 return NULL;
4076 }
4077
4078 #ifndef PRODUCT
4079 bool GCLabBitMapClosure::do_bit(size_t offset) {
4080 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4081 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4082 return true;
4083 }
4084 #endif // PRODUCT
4085
4086 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4087 : _g1h(g1h),
4088 _refs(g1h->task_queue(queue_num)),
4089 _dcq(&g1h->dirty_card_queue_set()),
4090 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4091 _g1_rem(g1h->g1_rem_set()),
4092 _hash_seed(17), _queue_num(queue_num),
4093 _term_attempts(0),
4094 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4095 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4096 _age_table(false),
4097 _strong_roots_time(0), _term_time(0),
4098 _alloc_buffer_waste(0), _undo_waste(0)
4099 {
4100 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4101 // we "sacrifice" entry 0 to keep track of surviving bytes for
4102 // non-young regions (where the age is -1)
4103 // We also add a few elements at the beginning and at the end in
4104 // an attempt to eliminate cache contention
4105 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4106 size_t array_length = PADDING_ELEM_NUM +
4107 real_length +
4108 PADDING_ELEM_NUM;
4109 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4110 if (_surviving_young_words_base == NULL)
4111 vm_exit_out_of_memory(array_length * sizeof(size_t),
4112 "Not enough space for young surv histo.");
4113 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4114 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4115
4116 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4117 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4118
4119 _start = os::elapsedTime();
4120 }
4121
4122 void
4123 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4124 {
4125 st->print_raw_cr("GC Termination Stats");
4126 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4127 " ------waste (KiB)------");
4128 st->print_raw_cr("thr ms ms % ms % attempts"
4129 " total alloc undo");
4130 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4131 " ------- ------- -------");
4132 }
4133
4134 void
4135 G1ParScanThreadState::print_termination_stats(int i,
4136 outputStream* const st) const
4137 {
4138 const double elapsed_ms = elapsed_time() * 1000.0;
4139 const double s_roots_ms = strong_roots_time() * 1000.0;
4140 const double term_ms = term_time() * 1000.0;
4141 st->print_cr("%3d %9.2f %9.2f %6.2f "
4142 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4143 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4144 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4145 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4146 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4147 alloc_buffer_waste() * HeapWordSize / K,
4148 undo_waste() * HeapWordSize / K);
4149 }
4150
4151 #ifdef ASSERT
4152 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4153 assert(ref != NULL, "invariant");
4154 assert(UseCompressedOops, "sanity");
4155 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4156 oop p = oopDesc::load_decode_heap_oop(ref);
4157 assert(_g1h->is_in_g1_reserved(p),
4158 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4159 return true;
4160 }
4161
4162 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4163 assert(ref != NULL, "invariant");
4164 if (has_partial_array_mask(ref)) {
4165 // Must be in the collection set--it's already been copied.
4166 oop p = clear_partial_array_mask(ref);
4167 assert(_g1h->obj_in_cs(p),
4168 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4169 } else {
4170 oop p = oopDesc::load_decode_heap_oop(ref);
4171 assert(_g1h->is_in_g1_reserved(p),
4172 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4173 }
4174 return true;
4175 }
4176
4177 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4178 if (ref.is_narrow()) {
4179 return verify_ref((narrowOop*) ref);
4180 } else {
4181 return verify_ref((oop*) ref);
4182 }
4183 }
4184 #endif // ASSERT
4185
4186 void G1ParScanThreadState::trim_queue() {
4187 StarTask ref;
4188 do {
4189 // Drain the overflow stack first, so other threads can steal.
4190 while (refs()->pop_overflow(ref)) {
4191 deal_with_reference(ref);
4192 }
4193 while (refs()->pop_local(ref)) {
4194 deal_with_reference(ref);
4195 }
4196 } while (!refs()->is_empty());
4197 }
4198
4199 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4200 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4201 _par_scan_state(par_scan_state) { }
4202
4203 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
4204 // This is called _after_ do_oop_work has been called, hence after
4205 // the object has been relocated to its new location and *p points
4206 // to its new location.
4207
4208 T heap_oop = oopDesc::load_heap_oop(p);
4209 if (!oopDesc::is_null(heap_oop)) {
4210 oop obj = oopDesc::decode_heap_oop(heap_oop);
4211 HeapWord* addr = (HeapWord*)obj;
4212 if (_g1->is_in_g1_reserved(addr)) {
4213 _cm->grayRoot(oop(addr));
4214 }
4215 }
4216 }
4217
4218 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4219 size_t word_sz = old->size();
4220 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4221 // +1 to make the -1 indexes valid...
4222 int young_index = from_region->young_index_in_cset()+1;
4223 assert( (from_region->is_young() && young_index > 0) ||
4224 (!from_region->is_young() && young_index == 0), "invariant" );
4225 G1CollectorPolicy* g1p = _g1->g1_policy();
4226 markOop m = old->mark();
4227 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4228 : m->age();
4229 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4230 word_sz);
4231 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4232 oop obj = oop(obj_ptr);
4233
4234 if (obj_ptr == NULL) {
4235 // This will either forward-to-self, or detect that someone else has
4236 // installed a forwarding pointer.
4237 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4238 return _g1->handle_evacuation_failure_par(cl, old);
4239 }
4240
4241 // We're going to allocate linearly, so might as well prefetch ahead.
4242 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4243
4244 oop forward_ptr = old->forward_to_atomic(obj);
4245 if (forward_ptr == NULL) {
4246 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4247 if (g1p->track_object_age(alloc_purpose)) {
4248 // We could simply do obj->incr_age(). However, this causes a
4249 // performance issue. obj->incr_age() will first check whether
4250 // the object has a displaced mark by checking its mark word;
4251 // getting the mark word from the new location of the object
4252 // stalls. So, given that we already have the mark word and we
4253 // are about to install it anyway, it's better to increase the
4254 // age on the mark word, when the object does not have a
4255 // displaced mark word. We're not expecting many objects to have
4256 // a displaced marked word, so that case is not optimized
4257 // further (it could be...) and we simply call obj->incr_age().
4258
4259 if (m->has_displaced_mark_helper()) {
4260 // in this case, we have to install the mark word first,
4261 // otherwise obj looks to be forwarded (the old mark word,
4262 // which contains the forward pointer, was copied)
4263 obj->set_mark(m);
4264 obj->incr_age();
4265 } else {
4266 m = m->incr_age();
4267 obj->set_mark(m);
4268 }
4269 _par_scan_state->age_table()->add(obj, word_sz);
4270 } else {
4271 obj->set_mark(m);
4272 }
4273
4274 // preserve "next" mark bit
4275 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4276 if (!use_local_bitmaps ||
4277 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4278 // if we couldn't mark it on the local bitmap (this happens when
4279 // the object was not allocated in the GCLab), we have to bite
4280 // the bullet and do the standard parallel mark
4281 _cm->markAndGrayObjectIfNecessary(obj);
4282 }
4283 #if 1
4284 if (_g1->isMarkedNext(old)) {
4285 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4286 }
4287 #endif
4288 }
4289
4290 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4291 surv_young_words[young_index] += word_sz;
4292
4293 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4294 arrayOop(old)->set_length(0);
4295 oop* old_p = set_partial_array_mask(old);
4296 _par_scan_state->push_on_queue(old_p);
4297 } else {
4298 // No point in using the slower heap_region_containing() method,
4299 // given that we know obj is in the heap.
4300 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4301 obj->oop_iterate_backwards(_scanner);
4302 }
4303 } else {
4304 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4305 obj = forward_ptr;
4306 }
4307 return obj;
4308 }
4309
4310 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4311 template <class T>
4312 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4313 ::do_oop_work(T* p) {
4314 oop obj = oopDesc::load_decode_heap_oop(p);
4315 assert(barrier != G1BarrierRS || obj != NULL,
4316 "Precondition: G1BarrierRS implies obj is nonNull");
4317
4318 // here the null check is implicit in the cset_fast_test() test
4319 if (_g1->in_cset_fast_test(obj)) {
4320 if (obj->is_forwarded()) {
4321 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4322 } else {
4323 oop copy_oop = copy_to_survivor_space(obj);
4324 oopDesc::encode_store_heap_oop(p, copy_oop);
4325 }
4326 // When scanning the RS, we only care about objs in CS.
4327 if (barrier == G1BarrierRS) {
4328 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4329 }
4330 }
4331
4332 if (barrier == G1BarrierEvac && obj != NULL) {
4333 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4334 }
4335
4336 if (do_gen_barrier && obj != NULL) {
4337 par_do_barrier(p);
4338 }
4339 }
4340
4341 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4342 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4343
4344 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4345 assert(has_partial_array_mask(p), "invariant");
4346 oop old = clear_partial_array_mask(p);
4347 assert(old->is_objArray(), "must be obj array");
4348 assert(old->is_forwarded(), "must be forwarded");
4349 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4350
4351 objArrayOop obj = objArrayOop(old->forwardee());
4352 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4353 // Process ParGCArrayScanChunk elements now
4354 // and push the remainder back onto queue
4355 int start = arrayOop(old)->length();
4356 int end = obj->length();
4357 int remainder = end - start;
4358 assert(start <= end, "just checking");
4359 if (remainder > 2 * ParGCArrayScanChunk) {
4360 // Test above combines last partial chunk with a full chunk
4361 end = start + ParGCArrayScanChunk;
4362 arrayOop(old)->set_length(end);
4363 // Push remainder.
4364 oop* old_p = set_partial_array_mask(old);
4365 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4366 _par_scan_state->push_on_queue(old_p);
4367 } else {
4368 // Restore length so that the heap remains parsable in
4369 // case of evacuation failure.
4370 arrayOop(old)->set_length(end);
4371 }
4372 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4373 // process our set of indices (include header in first chunk)
4374 obj->oop_iterate_range(&_scanner, start, end);
4375 }
4376
4377 class G1ParEvacuateFollowersClosure : public VoidClosure {
4378 protected:
4379 G1CollectedHeap* _g1h;
4380 G1ParScanThreadState* _par_scan_state;
4381 RefToScanQueueSet* _queues;
4382 ParallelTaskTerminator* _terminator;
4383
4384 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4385 RefToScanQueueSet* queues() { return _queues; }
4386 ParallelTaskTerminator* terminator() { return _terminator; }
4387
4388 public:
4389 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4390 G1ParScanThreadState* par_scan_state,
4391 RefToScanQueueSet* queues,
4392 ParallelTaskTerminator* terminator)
4393 : _g1h(g1h), _par_scan_state(par_scan_state),
4394 _queues(queues), _terminator(terminator) {}
4395
4396 void do_void();
4397
4398 private:
4399 inline bool offer_termination();
4400 };
4401
4402 bool G1ParEvacuateFollowersClosure::offer_termination() {
4403 G1ParScanThreadState* const pss = par_scan_state();
4404 pss->start_term_time();
4405 const bool res = terminator()->offer_termination();
4406 pss->end_term_time();
4407 return res;
4408 }
4409
4410 void G1ParEvacuateFollowersClosure::do_void() {
4411 StarTask stolen_task;
4412 G1ParScanThreadState* const pss = par_scan_state();
4413 pss->trim_queue();
4414
4415 do {
4416 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4417 assert(pss->verify_task(stolen_task), "sanity");
4418 if (stolen_task.is_narrow()) {
4419 pss->deal_with_reference((narrowOop*) stolen_task);
4420 } else {
4421 pss->deal_with_reference((oop*) stolen_task);
4422 }
4423
4424 // We've just processed a reference and we might have made
4425 // available new entries on the queues. So we have to make sure
4426 // we drain the queues as necessary.
4427 pss->trim_queue();
4428 }
4429 } while (!offer_termination());
4430
4431 pss->retire_alloc_buffers();
4432 }
4433
4434 class G1ParTask : public AbstractGangTask {
4435 protected:
4436 G1CollectedHeap* _g1h;
4437 RefToScanQueueSet *_queues;
4438 ParallelTaskTerminator _terminator;
4439 int _n_workers;
4440
4441 Mutex _stats_lock;
4442 Mutex* stats_lock() { return &_stats_lock; }
4443
4444 size_t getNCards() {
4445 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4446 / G1BlockOffsetSharedArray::N_bytes;
4447 }
4448
4449 public:
4450 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4451 : AbstractGangTask("G1 collection"),
4452 _g1h(g1h),
4453 _queues(task_queues),
4454 _terminator(workers, _queues),
4455 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4456 _n_workers(workers)
4457 {}
4458
4459 RefToScanQueueSet* queues() { return _queues; }
4460
4461 RefToScanQueue *work_queue(int i) {
4462 return queues()->queue(i);
4463 }
4464
4465 void work(int i) {
4466 if (i >= _n_workers) return; // no work needed this round
4467
4468 double start_time_ms = os::elapsedTime() * 1000.0;
4469 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4470
4471 ResourceMark rm;
4472 HandleMark hm;
4473
4474 G1ParScanThreadState pss(_g1h, i);
4475 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4476 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4477 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4478
4479 pss.set_evac_closure(&scan_evac_cl);
4480 pss.set_evac_failure_closure(&evac_failure_cl);
4481 pss.set_partial_scan_closure(&partial_scan_cl);
4482
4483 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4484 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4485 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4486 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4487
4488 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4489 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4490 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4491
4492 OopsInHeapRegionClosure *scan_root_cl;
4493 OopsInHeapRegionClosure *scan_perm_cl;
4494
4495 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4496 scan_root_cl = &scan_mark_root_cl;
4497 scan_perm_cl = &scan_mark_perm_cl;
4498 } else {
4499 scan_root_cl = &only_scan_root_cl;
4500 scan_perm_cl = &only_scan_perm_cl;
4501 }
4502
4503 pss.start_strong_roots();
4504 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4505 SharedHeap::SO_AllClasses,
4506 scan_root_cl,
4507 &push_heap_rs_cl,
4508 scan_perm_cl,
4509 i);
4510 pss.end_strong_roots();
4511
4512 {
4513 double start = os::elapsedTime();
4514 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4515 evac.do_void();
4516 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4517 double term_ms = pss.term_time()*1000.0;
4518 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4519 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4520 }
4521 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4522 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4523
4524 // Clean up any par-expanded rem sets.
4525 HeapRegionRemSet::par_cleanup();
4526
4527 if (ParallelGCVerbose) {
4528 MutexLocker x(stats_lock());
4529 pss.print_termination_stats(i);
4530 }
4531
4532 assert(pss.refs()->is_empty(), "should be empty");
4533 double end_time_ms = os::elapsedTime() * 1000.0;
4534 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4535 }
4536 };
4537
4538 // *** Common G1 Evacuation Stuff
4539
4540 // This method is run in a GC worker.
4541
4542 void
4543 G1CollectedHeap::
4544 g1_process_strong_roots(bool collecting_perm_gen,
4545 SharedHeap::ScanningOption so,
4546 OopClosure* scan_non_heap_roots,
4547 OopsInHeapRegionClosure* scan_rs,
4548 OopsInGenClosure* scan_perm,
4549 int worker_i) {
4550 // First scan the strong roots, including the perm gen.
4551 double ext_roots_start = os::elapsedTime();
4552 double closure_app_time_sec = 0.0;
4553
4554 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4555 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4556 buf_scan_perm.set_generation(perm_gen());
4557
4558 // Walk the code cache w/o buffering, because StarTask cannot handle
4559 // unaligned oop locations.
4560 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4561
4562 process_strong_roots(false, // no scoping; this is parallel code
4563 collecting_perm_gen, so,
4564 &buf_scan_non_heap_roots,
4565 &eager_scan_code_roots,
4566 &buf_scan_perm);
4567
4568 // Now the ref_processor roots.
4569 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4570 // We need to treat the discovered reference lists as roots and
4571 // keep entries (which are added by the marking threads) on them
4572 // live until they can be processed at the end of marking.
4573 ref_processor()->weak_oops_do(&buf_scan_non_heap_roots);
4574 ref_processor()->oops_do(&buf_scan_non_heap_roots);
4575 }
4576
4577 // Finish up any enqueued closure apps (attributed as object copy time).
4578 buf_scan_non_heap_roots.done();
4579 buf_scan_perm.done();
4580
4581 double ext_roots_end = os::elapsedTime();
4582
4583 g1_policy()->reset_obj_copy_time(worker_i);
4584 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4585 buf_scan_non_heap_roots.closure_app_seconds();
4586 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4587
4588 double ext_root_time_ms =
4589 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4590
4591 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4592
4593 // Scan strong roots in mark stack.
4594 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4595 concurrent_mark()->oops_do(scan_non_heap_roots);
4596 }
4597 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4598 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4599
4600 // Now scan the complement of the collection set.
4601 if (scan_rs != NULL) {
4602 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4603 }
4604
4605 _process_strong_tasks->all_tasks_completed();
4606 }
4607
4608 void
4609 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4610 OopClosure* non_root_closure) {
4611 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4612 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4613 }
4614
4615 void G1CollectedHeap::evacuate_collection_set() {
4616 set_evacuation_failed(false);
4617
4618 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4619 concurrent_g1_refine()->set_use_cache(false);
4620 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4621
4622 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4623 set_par_threads(n_workers);
4624 G1ParTask g1_par_task(this, n_workers, _task_queues);
4625
4626 init_for_evac_failure(NULL);
4627
4628 rem_set()->prepare_for_younger_refs_iterate(true);
4629
4630 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4631 double start_par = os::elapsedTime();
4632 if (G1CollectedHeap::use_parallel_gc_threads()) {
4633 // The individual threads will set their evac-failure closures.
4634 StrongRootsScope srs(this);
4635 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4636 workers()->run_task(&g1_par_task);
4637 } else {
4638 StrongRootsScope srs(this);
4639 g1_par_task.work(0);
4640 }
4641
4642 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4643 g1_policy()->record_par_time(par_time);
4644 set_par_threads(0);
4645
4646 // Weak root processing.
4647 // Note: when JSR 292 is enabled and code blobs can contain
4648 // non-perm oops then we will need to process the code blobs
4649 // here too.
4650 {
4651 G1IsAliveClosure is_alive(this);
4652 G1KeepAliveClosure keep_alive(this);
4653 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4654 }
4655 release_gc_alloc_regions();
4656 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4657
4658 concurrent_g1_refine()->clear_hot_cache();
4659 concurrent_g1_refine()->set_use_cache(true);
4660
4661 finalize_for_evac_failure();
4662
4663 // Must do this before removing self-forwarding pointers, which clears
4664 // the per-region evac-failure flags.
4665 concurrent_mark()->complete_marking_in_collection_set();
4666
4667 if (evacuation_failed()) {
4668 remove_self_forwarding_pointers();
4669 if (PrintGCDetails) {
4670 gclog_or_tty->print(" (to-space overflow)");
4671 } else if (PrintGC) {
4672 gclog_or_tty->print("--");
4673 }
4674 }
4675
4676 if (G1DeferredRSUpdate) {
4677 RedirtyLoggedCardTableEntryFastClosure redirty;
4678 dirty_card_queue_set().set_closure(&redirty);
4679 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4680
4681 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4682 dcq.merge_bufferlists(&dirty_card_queue_set());
4683 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4684 }
4685 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4686 }
4687
4688 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
4689 size_t* pre_used,
4690 FreeRegionList* free_list,
4691 HumongousRegionSet* humongous_proxy_set,
4692 HRRSCleanupTask* hrrs_cleanup_task,
4693 bool par) {
4694 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
4695 if (hr->isHumongous()) {
4696 assert(hr->startsHumongous(), "we should only see starts humongous");
4697 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
4698 } else {
4699 free_region(hr, pre_used, free_list, par);
4700 }
4701 } else {
4702 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
4703 }
4704 }
4705
4706 void G1CollectedHeap::free_region(HeapRegion* hr,
4707 size_t* pre_used,
4708 FreeRegionList* free_list,
4709 bool par) {
4710 assert(!hr->isHumongous(), "this is only for non-humongous regions");
4711 assert(!hr->is_empty(), "the region should not be empty");
4712 assert(free_list != NULL, "pre-condition");
4713
4714 *pre_used += hr->used();
4715 hr->hr_clear(par, true /* clear_space */);
4716 free_list->add_as_head(hr);
4717 }
4718
4719 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4720 size_t* pre_used,
4721 FreeRegionList* free_list,
4722 HumongousRegionSet* humongous_proxy_set,
4723 bool par) {
4724 assert(hr->startsHumongous(), "this is only for starts humongous regions");
4725 assert(free_list != NULL, "pre-condition");
4726 assert(humongous_proxy_set != NULL, "pre-condition");
4727
4728 size_t hr_used = hr->used();
4729 size_t hr_capacity = hr->capacity();
4730 size_t hr_pre_used = 0;
4731 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
4732 hr->set_notHumongous();
4733 free_region(hr, &hr_pre_used, free_list, par);
4734
4735 size_t i = hr->hrs_index() + 1;
4736 size_t num = 1;
4737 while (i < n_regions()) {
4738 HeapRegion* curr_hr = region_at(i);
4739 if (!curr_hr->continuesHumongous()) {
4740 break;
4741 }
4742 curr_hr->set_notHumongous();
4743 free_region(curr_hr, &hr_pre_used, free_list, par);
4744 num += 1;
4745 i += 1;
4746 }
4747 assert(hr_pre_used == hr_used,
4748 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
4749 "should be the same", hr_pre_used, hr_used));
4750 *pre_used += hr_pre_used;
4751 }
4752
4753 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
4754 FreeRegionList* free_list,
4755 HumongousRegionSet* humongous_proxy_set,
4756 bool par) {
4757 if (pre_used > 0) {
4758 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
4759 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4760 assert(_summary_bytes_used >= pre_used,
4761 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
4762 "should be >= pre_used: "SIZE_FORMAT,
4763 _summary_bytes_used, pre_used));
4764 _summary_bytes_used -= pre_used;
4765 }
4766 if (free_list != NULL && !free_list->is_empty()) {
4767 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4768 _free_list.add_as_head(free_list);
4769 }
4770 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
4771 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4772 _humongous_set.update_from_proxy(humongous_proxy_set);
4773 }
4774 }
4775
4776 class G1ParCleanupCTTask : public AbstractGangTask {
4777 CardTableModRefBS* _ct_bs;
4778 G1CollectedHeap* _g1h;
4779 HeapRegion* volatile _su_head;
4780 public:
4781 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4782 G1CollectedHeap* g1h) :
4783 AbstractGangTask("G1 Par Cleanup CT Task"),
4784 _ct_bs(ct_bs), _g1h(g1h) { }
4785
4786 void work(int i) {
4787 HeapRegion* r;
4788 while (r = _g1h->pop_dirty_cards_region()) {
4789 clear_cards(r);
4790 }
4791 }
4792
4793 void clear_cards(HeapRegion* r) {
4794 // Cards of the survivors should have already been dirtied.
4795 if (!r->is_survivor()) {
4796 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4797 }
4798 }
4799 };
4800
4801 #ifndef PRODUCT
4802 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4803 G1CollectedHeap* _g1h;
4804 CardTableModRefBS* _ct_bs;
4805 public:
4806 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
4807 : _g1h(g1h), _ct_bs(ct_bs) { }
4808 virtual bool doHeapRegion(HeapRegion* r) {
4809 if (r->is_survivor()) {
4810 _g1h->verify_dirty_region(r);
4811 } else {
4812 _g1h->verify_not_dirty_region(r);
4813 }
4814 return false;
4815 }
4816 };
4817
4818 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
4819 // All of the region should be clean.
4820 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
4821 MemRegion mr(hr->bottom(), hr->end());
4822 ct_bs->verify_not_dirty_region(mr);
4823 }
4824
4825 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
4826 // We cannot guarantee that [bottom(),end()] is dirty. Threads
4827 // dirty allocated blocks as they allocate them. The thread that
4828 // retires each region and replaces it with a new one will do a
4829 // maximal allocation to fill in [pre_dummy_top(),end()] but will
4830 // not dirty that area (one less thing to have to do while holding
4831 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
4832 // is dirty.
4833 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
4834 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
4835 ct_bs->verify_dirty_region(mr);
4836 }
4837
4838 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
4839 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
4840 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
4841 verify_dirty_region(hr);
4842 }
4843 }
4844
4845 void G1CollectedHeap::verify_dirty_young_regions() {
4846 verify_dirty_young_list(_young_list->first_region());
4847 verify_dirty_young_list(_young_list->first_survivor_region());
4848 }
4849 #endif
4850
4851 void G1CollectedHeap::cleanUpCardTable() {
4852 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4853 double start = os::elapsedTime();
4854
4855 // Iterate over the dirty cards region list.
4856 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4857
4858 if (ParallelGCThreads > 0) {
4859 set_par_threads(workers()->total_workers());
4860 workers()->run_task(&cleanup_task);
4861 set_par_threads(0);
4862 } else {
4863 while (_dirty_cards_region_list) {
4864 HeapRegion* r = _dirty_cards_region_list;
4865 cleanup_task.clear_cards(r);
4866 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4867 if (_dirty_cards_region_list == r) {
4868 // The last region.
4869 _dirty_cards_region_list = NULL;
4870 }
4871 r->set_next_dirty_cards_region(NULL);
4872 }
4873 }
4874
4875 double elapsed = os::elapsedTime() - start;
4876 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4877 #ifndef PRODUCT
4878 if (G1VerifyCTCleanup || VerifyAfterGC) {
4879 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
4880 heap_region_iterate(&cleanup_verifier);
4881 }
4882 #endif
4883 }
4884
4885 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4886 size_t pre_used = 0;
4887 FreeRegionList local_free_list("Local List for CSet Freeing");
4888
4889 double young_time_ms = 0.0;
4890 double non_young_time_ms = 0.0;
4891
4892 // Since the collection set is a superset of the the young list,
4893 // all we need to do to clear the young list is clear its
4894 // head and length, and unlink any young regions in the code below
4895 _young_list->clear();
4896
4897 G1CollectorPolicy* policy = g1_policy();
4898
4899 double start_sec = os::elapsedTime();
4900 bool non_young = true;
4901
4902 HeapRegion* cur = cs_head;
4903 int age_bound = -1;
4904 size_t rs_lengths = 0;
4905
4906 while (cur != NULL) {
4907 assert(!is_on_master_free_list(cur), "sanity");
4908
4909 if (non_young) {
4910 if (cur->is_young()) {
4911 double end_sec = os::elapsedTime();
4912 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4913 non_young_time_ms += elapsed_ms;
4914
4915 start_sec = os::elapsedTime();
4916 non_young = false;
4917 }
4918 } else {
4919 double end_sec = os::elapsedTime();
4920 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4921 young_time_ms += elapsed_ms;
4922
4923 start_sec = os::elapsedTime();
4924 non_young = true;
4925 }
4926
4927 rs_lengths += cur->rem_set()->occupied();
4928
4929 HeapRegion* next = cur->next_in_collection_set();
4930 assert(cur->in_collection_set(), "bad CS");
4931 cur->set_next_in_collection_set(NULL);
4932 cur->set_in_collection_set(false);
4933
4934 if (cur->is_young()) {
4935 int index = cur->young_index_in_cset();
4936 guarantee( index != -1, "invariant" );
4937 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4938 size_t words_survived = _surviving_young_words[index];
4939 cur->record_surv_words_in_group(words_survived);
4940
4941 // At this point the we have 'popped' cur from the collection set
4942 // (linked via next_in_collection_set()) but it is still in the
4943 // young list (linked via next_young_region()). Clear the
4944 // _next_young_region field.
4945 cur->set_next_young_region(NULL);
4946 } else {
4947 int index = cur->young_index_in_cset();
4948 guarantee( index == -1, "invariant" );
4949 }
4950
4951 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4952 (!cur->is_young() && cur->young_index_in_cset() == -1),
4953 "invariant" );
4954
4955 if (!cur->evacuation_failed()) {
4956 // And the region is empty.
4957 assert(!cur->is_empty(), "Should not have empty regions in a CS.");
4958 free_region(cur, &pre_used, &local_free_list, false /* par */);
4959 } else {
4960 cur->uninstall_surv_rate_group();
4961 if (cur->is_young())
4962 cur->set_young_index_in_cset(-1);
4963 cur->set_not_young();
4964 cur->set_evacuation_failed(false);
4965 }
4966 cur = next;
4967 }
4968
4969 policy->record_max_rs_lengths(rs_lengths);
4970 policy->cset_regions_freed();
4971
4972 double end_sec = os::elapsedTime();
4973 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4974 if (non_young)
4975 non_young_time_ms += elapsed_ms;
4976 else
4977 young_time_ms += elapsed_ms;
4978
4979 update_sets_after_freeing_regions(pre_used, &local_free_list,
4980 NULL /* humongous_proxy_set */,
4981 false /* par */);
4982 policy->record_young_free_cset_time_ms(young_time_ms);
4983 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4984 }
4985
4986 // This routine is similar to the above but does not record
4987 // any policy statistics or update free lists; we are abandoning
4988 // the current incremental collection set in preparation of a
4989 // full collection. After the full GC we will start to build up
4990 // the incremental collection set again.
4991 // This is only called when we're doing a full collection
4992 // and is immediately followed by the tearing down of the young list.
4993
4994 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
4995 HeapRegion* cur = cs_head;
4996
4997 while (cur != NULL) {
4998 HeapRegion* next = cur->next_in_collection_set();
4999 assert(cur->in_collection_set(), "bad CS");
5000 cur->set_next_in_collection_set(NULL);
5001 cur->set_in_collection_set(false);
5002 cur->set_young_index_in_cset(-1);
5003 cur = next;
5004 }
5005 }
5006
5007 void G1CollectedHeap::set_free_regions_coming() {
5008 if (G1ConcRegionFreeingVerbose) {
5009 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5010 "setting free regions coming");
5011 }
5012
5013 assert(!free_regions_coming(), "pre-condition");
5014 _free_regions_coming = true;
5015 }
5016
5017 void G1CollectedHeap::reset_free_regions_coming() {
5018 {
5019 assert(free_regions_coming(), "pre-condition");
5020 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5021 _free_regions_coming = false;
5022 SecondaryFreeList_lock->notify_all();
5023 }
5024
5025 if (G1ConcRegionFreeingVerbose) {
5026 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5027 "reset free regions coming");
5028 }
5029 }
5030
5031 void G1CollectedHeap::wait_while_free_regions_coming() {
5032 // Most of the time we won't have to wait, so let's do a quick test
5033 // first before we take the lock.
5034 if (!free_regions_coming()) {
5035 return;
5036 }
5037
5038 if (G1ConcRegionFreeingVerbose) {
5039 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5040 "waiting for free regions");
5041 }
5042
5043 {
5044 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5045 while (free_regions_coming()) {
5046 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5047 }
5048 }
5049
5050 if (G1ConcRegionFreeingVerbose) {
5051 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5052 "done waiting for free regions");
5053 }
5054 }
5055
5056 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5057 assert(heap_lock_held_for_gc(),
5058 "the heap lock should already be held by or for this thread");
5059 _young_list->push_region(hr);
5060 g1_policy()->set_region_short_lived(hr);
5061 }
5062
5063 class NoYoungRegionsClosure: public HeapRegionClosure {
5064 private:
5065 bool _success;
5066 public:
5067 NoYoungRegionsClosure() : _success(true) { }
5068 bool doHeapRegion(HeapRegion* r) {
5069 if (r->is_young()) {
5070 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5071 r->bottom(), r->end());
5072 _success = false;
5073 }
5074 return false;
5075 }
5076 bool success() { return _success; }
5077 };
5078
5079 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5080 bool ret = _young_list->check_list_empty(check_sample);
5081
5082 if (check_heap) {
5083 NoYoungRegionsClosure closure;
5084 heap_region_iterate(&closure);
5085 ret = ret && closure.success();
5086 }
5087
5088 return ret;
5089 }
5090
5091 void G1CollectedHeap::empty_young_list() {
5092 assert(heap_lock_held_for_gc(),
5093 "the heap lock should already be held by or for this thread");
5094 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5095
5096 _young_list->empty_list();
5097 }
5098
5099 // Done at the start of full GC.
5100 void G1CollectedHeap::tear_down_region_lists() {
5101 _free_list.remove_all();
5102 }
5103
5104 class RegionResetter: public HeapRegionClosure {
5105 G1CollectedHeap* _g1h;
5106 FreeRegionList _local_free_list;
5107
5108 public:
5109 RegionResetter() : _g1h(G1CollectedHeap::heap()),
5110 _local_free_list("Local Free List for RegionResetter") { }
5111
5112 bool doHeapRegion(HeapRegion* r) {
5113 if (r->continuesHumongous()) return false;
5114 if (r->top() > r->bottom()) {
5115 if (r->top() < r->end()) {
5116 Copy::fill_to_words(r->top(),
5117 pointer_delta(r->end(), r->top()));
5118 }
5119 } else {
5120 assert(r->is_empty(), "tautology");
5121 _local_free_list.add_as_tail(r);
5122 }
5123 return false;
5124 }
5125
5126 void update_free_lists() {
5127 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
5128 false /* par */);
5129 }
5130 };
5131
5132 // Done at the end of full GC.
5133 void G1CollectedHeap::rebuild_region_lists() {
5134 // This needs to go at the end of the full GC.
5135 RegionResetter rs;
5136 heap_region_iterate(&rs);
5137 rs.update_free_lists();
5138 }
5139
5140 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5141 _refine_cte_cl->set_concurrent(concurrent);
5142 }
5143
5144 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5145 HeapRegion* hr = heap_region_containing(p);
5146 if (hr == NULL) {
5147 return is_in_permanent(p);
5148 } else {
5149 return hr->is_in(p);
5150 }
5151 }
5152
5153 // Methods for the mutator alloc region
5154
5155 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5156 bool force) {
5157 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5158 assert(!force || g1_policy()->can_expand_young_list(),
5159 "if force is true we should be able to expand the young list");
5160 bool young_list_full = g1_policy()->is_young_list_full();
5161 if (force || !young_list_full) {
5162 HeapRegion* new_alloc_region = new_region(word_size,
5163 false /* do_expand */);
5164 if (new_alloc_region != NULL) {
5165 g1_policy()->update_region_num(true /* next_is_young */);
5166 set_region_short_lived_locked(new_alloc_region);
5167 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
5168 g1mm()->update_eden_counters();
5169 return new_alloc_region;
5170 }
5171 }
5172 return NULL;
5173 }
5174
5175 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5176 size_t allocated_bytes) {
5177 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5178 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
5179
5180 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5181 _summary_bytes_used += allocated_bytes;
5182 _hr_printer.retire(alloc_region);
5183 }
5184
5185 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
5186 bool force) {
5187 return _g1h->new_mutator_alloc_region(word_size, force);
5188 }
5189
5190 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
5191 size_t allocated_bytes) {
5192 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
5193 }
5194
5195 // Methods for the GC alloc regions
5196
5197 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5198 size_t count,
5199 GCAllocPurpose ap) {
5200 assert(FreeList_lock->owned_by_self(), "pre-condition");
5201
5202 if (count < g1_policy()->max_regions(ap)) {
5203 HeapRegion* new_alloc_region = new_region(word_size,
5204 true /* do_expand */);
5205 if (new_alloc_region != NULL) {
5206 // We really only need to do this for old regions given that we
5207 // should never scan survivors. But it doesn't hurt to do it
5208 // for survivors too.
5209 new_alloc_region->set_saved_mark();
5210 if (ap == GCAllocForSurvived) {
5211 new_alloc_region->set_survivor();
5212 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
5213 } else {
5214 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
5215 }
5216 return new_alloc_region;
5217 } else {
5218 g1_policy()->note_alloc_region_limit_reached(ap);
5219 }
5220 }
5221 return NULL;
5222 }
5223
5224 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5225 size_t allocated_bytes,
5226 GCAllocPurpose ap) {
5227 alloc_region->note_end_of_copying();
5228 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5229 if (ap == GCAllocForSurvived) {
5230 young_list()->add_survivor_region(alloc_region);
5231 }
5232 _hr_printer.retire(alloc_region);
5233 }
5234
5235 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
5236 bool force) {
5237 assert(!force, "not supported for GC alloc regions");
5238 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
5239 }
5240
5241 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
5242 size_t allocated_bytes) {
5243 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
5244 GCAllocForSurvived);
5245 }
5246
5247 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
5248 bool force) {
5249 assert(!force, "not supported for GC alloc regions");
5250 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
5251 }
5252
5253 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
5254 size_t allocated_bytes) {
5255 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
5256 GCAllocForTenured);
5257 }
5258 // Heap region set verification
5259
5260 class VerifyRegionListsClosure : public HeapRegionClosure {
5261 private:
5262 HumongousRegionSet* _humongous_set;
5263 FreeRegionList* _free_list;
5264 size_t _region_count;
5265
5266 public:
5267 VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
5268 FreeRegionList* free_list) :
5269 _humongous_set(humongous_set), _free_list(free_list),
5270 _region_count(0) { }
5271
5272 size_t region_count() { return _region_count; }
5273
5274 bool doHeapRegion(HeapRegion* hr) {
5275 _region_count += 1;
5276
5277 if (hr->continuesHumongous()) {
5278 return false;
5279 }
5280
5281 if (hr->is_young()) {
5282 // TODO
5283 } else if (hr->startsHumongous()) {
5284 _humongous_set->verify_next_region(hr);
5285 } else if (hr->is_empty()) {
5286 _free_list->verify_next_region(hr);
5287 }
5288 return false;
5289 }
5290 };
5291
5292 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
5293 HeapWord* bottom) {
5294 HeapWord* end = bottom + HeapRegion::GrainWords;
5295 MemRegion mr(bottom, end);
5296 assert(_g1_reserved.contains(mr), "invariant");
5297 // This might return NULL if the allocation fails
5298 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
5299 }
5300
5301 void G1CollectedHeap::verify_region_sets() {
5302 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5303
5304 // First, check the explicit lists.
5305 _free_list.verify();
5306 {
5307 // Given that a concurrent operation might be adding regions to
5308 // the secondary free list we have to take the lock before
5309 // verifying it.
5310 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5311 _secondary_free_list.verify();
5312 }
5313 _humongous_set.verify();
5314
5315 // If a concurrent region freeing operation is in progress it will
5316 // be difficult to correctly attributed any free regions we come
5317 // across to the correct free list given that they might belong to
5318 // one of several (free_list, secondary_free_list, any local lists,
5319 // etc.). So, if that's the case we will skip the rest of the
5320 // verification operation. Alternatively, waiting for the concurrent
5321 // operation to complete will have a non-trivial effect on the GC's
5322 // operation (no concurrent operation will last longer than the
5323 // interval between two calls to verification) and it might hide
5324 // any issues that we would like to catch during testing.
5325 if (free_regions_coming()) {
5326 return;
5327 }
5328
5329 // Make sure we append the secondary_free_list on the free_list so
5330 // that all free regions we will come across can be safely
5331 // attributed to the free_list.
5332 append_secondary_free_list_if_not_empty_with_lock();
5333
5334 // Finally, make sure that the region accounting in the lists is
5335 // consistent with what we see in the heap.
5336 _humongous_set.verify_start();
5337 _free_list.verify_start();
5338
5339 VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
5340 heap_region_iterate(&cl);
5341
5342 _humongous_set.verify_end();
5343 _free_list.verify_end();
5344 }