1 /*
2 * Copyright (c) 2001, 2015, 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 "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1AllocRegion.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "memory/allocation.hpp"
65 #include "memory/iterator.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/globalSynchronizer.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72 #include "utilities/stack.inline.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93 bool RefineCardTableEntryClosure::do_card_ptr(jbyte* card_ptr, uint worker_i) {
94 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
95 // This path is executed by the concurrent refine or mutator threads,
96 // concurrently, and so we do not care if card_ptr contains references
97 // that point into the collection set.
98 assert(!oops_into_cset, "should be");
99
100 // return false if caller should yield
101 return !(G1CollectedHeap::heap()->refine_cte_cl_concurrency() && SuspendibleThreadSet::should_yield());
102 }
103
104 CardBuffer::CardBuffer()
105 : _next(NULL) {
106 int size = BufferedRefineCardTableEntryClosure::buffer_size();
107 _card_buffer = NEW_C_HEAP_ARRAY(jbyte*, size, mtGC);
108 _mr_buffer = NEW_C_HEAP_ARRAY(MemRegion, size, mtGC);
109 _gs = new SynchronizerObj<mtGC>();
110 _misses = 0;
111 }
112
113 CardBuffer::~CardBuffer() {
114 FREE_C_HEAP_ARRAY(jbyte*, _card_buffer);
115 FREE_C_HEAP_ARRAY(MemRegion, _mr_buffer);
116 delete _gs;
117 }
118
119 BufferedRefineCardTableEntryClosure::BufferedRefineCardTableEntryClosure()
120 : _index(0), _g1h(G1CollectedHeap::heap()), _head_buffer(NULL), _tail_buffer(NULL),
121 _current_buffer(NULL), _async_buffers(0) {
122 }
123
124 BufferedRefineCardTableEntryClosure::~BufferedRefineCardTableEntryClosure() {
125 assert(_index == 0, "must flush refine card buffer");
126 assert(_head_buffer == NULL && _tail_buffer == NULL, "must flush all async cards first");
127 assert(_async_buffers == 0, "must flush all async cards first");
128 if (_current_buffer) delete _current_buffer;
129 }
130
131 bool BufferedRefineCardTableEntryClosure::do_card_ptr(jbyte *card_ptr, uint worker_i) {
132 _worker_i = worker_i;
133 if (_index == buffer_size()) soft_flush();
134 if (_current_buffer == NULL) _current_buffer = new CardBuffer();
135 _current_buffer->_card_buffer[_index++] = card_ptr;
136
137 bool should_yield = _g1h->refine_cte_cl_concurrency() && SuspendibleThreadSet::should_yield();
138 if (should_yield) flush_buffer();
139
140 // return false if caller should yield
141 return !should_yield;
142 }
143
144 void BufferedRefineCardTableEntryClosure::soft_flush() {
145 general_flush(false);
146 }
147
148 // Procedures used to sort and join G1 cards during refinement
149 static void quick_sort(jbyte **card_array, MemRegion *region_array, int left, int right);
150 static int partition(jbyte **card_array, MemRegion *region_array, int left, int right);
151 static int join_cards(jbyte **card_array, MemRegion *region_array, int length);
152
153 static void quick_sort(jbyte **card_array, MemRegion *region_array, int left, int right) {
154 int middle;
155 if (left < right)
156 {
157 middle = partition(card_array, region_array, left, right);
158 quick_sort(card_array, region_array, left, middle);
159 quick_sort(card_array, region_array, middle + 1, right);
160 }
161 }
162
163 static int partition(jbyte **card_array, MemRegion *region_array, int left, int right) {
164 jbyte *card = card_array[left];
165 int i = left;
166 int j;
167
168 for (j = left + 1; j < right; j++)
169 {
170 if (card_array[j] <= card)
171 {
172 i = i + 1;
173 swap(card_array[i], card_array[j]);
174 swap(region_array[i], region_array[j]);
175 }
176 }
177
178 swap(card_array[i], card_array[left]);
179 swap(region_array[i], region_array[left]);
180 return i;
181 }
182
183 static int join_cards(jbyte **card_array, MemRegion *region_array, int length) {
184 G1CollectedHeap *g1h = G1CollectedHeap::heap();
185 jbyte *prev_card = NULL;
186 HeapRegion *prev_hr = NULL;
187 int insert_head = 0;
188 for (int i = 0; i < length; i++) {
189 jbyte *card = card_array[i];
190
191 if (*card == CardTableModRefBS::clean_card_val()) {
192 HeapRegion *hr = g1h->heap_region_containing_raw(region_array[i].start());
193 if (card == prev_card + 1 && hr == prev_hr) {
194 MemRegion insert_region = region_array[insert_head - 1];
195 region_array[insert_head - 1] = MemRegion(insert_region.start(), region_array[i].end());
196 } else {
197 card_array[insert_head] = card;
198 region_array[insert_head] = region_array[i];
199 insert_head++;
200 }
201 prev_hr = hr;
202 }
203
204 prev_card = card;
205 }
206
207 return insert_head;
208 }
209
210 int BufferedRefineCardTableEntryClosure::buffer_size() {
211 return (int)G1UpdateBufferSize;
212 }
213
214 void BufferedRefineCardTableEntryClosure::flush_buffer() {
215 general_flush(true);
216 }
217
218 // Returns true if it needs post sync
219 bool BufferedRefineCardTableEntryClosure::pre_sync(CardBuffer *buffer, bool hard) {
220 // 1. Clean all cards in the batch.
221 G1RemSet *g1rs = G1CollectedHeap::heap()->g1_rem_set();
222 int needs_processing = 0;
223
224 jbyte **const card_buffer = buffer->_card_buffer;
225 MemRegion *const mr_buffer = buffer->_mr_buffer;
226 const int length = buffer->_length;
227
228 for (int i = 0; i < length; i++) {
229 if (g1rs->clean_card(card_buffer[i], _worker_i, mr_buffer[i])) {
230 card_buffer[needs_processing] = card_buffer[i];
231 mr_buffer[needs_processing] = mr_buffer[i];
232 needs_processing++;
233 }
234 }
235 buffer->_length = needs_processing;
236
237 if (needs_processing == 0) {
238 if (hard) {
239 // If we are forced to finish scanning, we must serialize stores anyway.
240 OrderAccess::storeload();
241 if (G1ElideMembar) {
242 buffer->_gs->start_synchronizing();
243 }
244 }
245 return false;
246 }
247
248 OrderAccess::storeload();
249 if (G1ElideMembar) {
250 buffer->_gs->start_synchronizing();
251 }
252
253 // 2. Sort the cards
254 quick_sort(buffer->_card_buffer, buffer->_mr_buffer, 0, buffer->_length);
255
256 return true;
257 }
258
259 bool BufferedRefineCardTableEntryClosure::sync(CardBuffer *buffer, bool hard) {
260 if (!G1ElideMembar) return true;
261
262 bool success = buffer->_gs->try_synchronize();
263 if (hard) {
264 if (!success) {
265 buffer->_gs->maximize_urgency();
266 buffer->_gs->synchronize();
267 }
268 return true;
269 } else {
270 return success;
271 }
272 }
273
274 void BufferedRefineCardTableEntryClosure::post_sync(CardBuffer *buffer) {
275 const int length = buffer->_length;
276
277 const int card_batch_size = 16;
278 jbyte **current_card = buffer->_card_buffer;
279 MemRegion *current_region = buffer->_mr_buffer;
280
281 const uintx interval = PrefetchScanIntervalInBytes * 2;
282
283 G1RemSet *g1rs = G1CollectedHeap::heap()->g1_rem_set();
284
285 // 3. Batch 16 cards at a time
286
287 for (int j = 0; j < length; j += card_batch_size) {
288 // 4. Join consecutive cards together and prefetch next card
289 int batch = MIN2((length - j), card_batch_size);
290 batch = join_cards(current_card, current_region, batch);
291
292 jbyte dirty_card_val = CardTableModRefBS::dirty_card_val();
293 jbyte *end_card;
294 HeapWord *end_prefetch;
295
296 if (j + card_batch_size < length) {
297 end_prefetch = current_region[card_batch_size].start();
298 end_card = current_card[card_batch_size];
299 } else {
300 end_card = &dirty_card_val;
301 }
302
303 MemRegion *region_end = current_region + batch;
304 jbyte** batch_card;
305 MemRegion* batch_region;
306
307 for (batch_card = current_card, batch_region = current_region; batch_region != region_end; batch_card++) {
308 jbyte *card = *batch_card;
309 MemRegion mr = *batch_region;
310 MemRegion *next_region = batch_region + 1;
311
312 if (next_region != region_end) {
313 MemRegion next_region_val = *next_region;
314 // Prefetch interval in batch
315 Prefetch::read(next_region_val.start(), next_region_val.byte_size());
316 } else if (*end_card == CardTableModRefBS::clean_card_val()) {
317 // Prefetch broken interval to next batch
318 Prefetch::read(end_prefetch, interval);
319 }
320
321 g1rs->refine_card_buffered(card, _worker_i, /*check_for_cset_refs*/ false, mr);
322
323 batch_region = next_region;
324 }
325
326 current_region += card_batch_size;
327 current_card += card_batch_size;
328 }
329 }
330
331 void BufferedRefineCardTableEntryClosure::general_flush(bool hard) {
332 if (_index == 0) {
333 assert(hard, "invariant");
334 if (_async_buffers == 0) return;
335 }
336
337 // 1. Start asynchronous synchronization for the current buffer
338 if (_current_buffer == NULL) _current_buffer = new CardBuffer();
339 _current_buffer->_length = _index;
340 if (pre_sync(_current_buffer, hard) || hard) {
341 // append async buffer
342 CardBuffer *tail = _tail_buffer;
343 if (tail != NULL) tail->_next = _current_buffer;
344 _tail_buffer = _current_buffer;
345 if (_head_buffer == NULL) _head_buffer = _current_buffer;
346 if (hard) sync(_current_buffer, hard);
347 _current_buffer = NULL;
348 _async_buffers++;
349 }
350
351 _index = 0;
352
353 // 2. Process old batches that have been cleaned but couldn't synchronize (async completion)
354 CardBuffer *current = _head_buffer;
355 bool check_sync = true;
356 while (current != NULL) {
357 if (hard || sync(current, hard)) {
358 post_sync(current);
359 CardBuffer *next = current->_next;
360 _head_buffer = next;
361 if (next == NULL) _tail_buffer = NULL;
362 delete current;
363 current = next;
364 _async_buffers--;
365 } else {
366 current->_misses++;
367 if (_async_buffers > 4 && current->_misses > 2
368 || _async_buffers > 8 && current->_misses > 4
369 || _async_buffers > 16 && current->_misses > 6) {
370 current->_gs->increase_urgency();
371 }
372 break;
373 }
374 }
375 }
376
377
378 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
379 private:
380 size_t _num_processed;
381
382 public:
383 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
384
385 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
386 *card_ptr = CardTableModRefBS::dirty_card_val();
387 _num_processed++;
388 return true;
389 }
390
391 size_t num_processed() const { return _num_processed; }
392 };
393
394 YoungList::YoungList(G1CollectedHeap* g1h) :
395 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
396 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
397 guarantee(check_list_empty(false), "just making sure...");
398 }
399
400 void YoungList::push_region(HeapRegion *hr) {
401 assert(!hr->is_young(), "should not already be young");
402 assert(hr->get_next_young_region() == NULL, "cause it should!");
403
404 hr->set_next_young_region(_head);
405 _head = hr;
406
407 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
408 ++_length;
409 }
410
411 void YoungList::add_survivor_region(HeapRegion* hr) {
412 assert(hr->is_survivor(), "should be flagged as survivor region");
413 assert(hr->get_next_young_region() == NULL, "cause it should!");
414
415 hr->set_next_young_region(_survivor_head);
416 if (_survivor_head == NULL) {
417 _survivor_tail = hr;
418 }
419 _survivor_head = hr;
420 ++_survivor_length;
421 }
422
423 void YoungList::empty_list(HeapRegion* list) {
424 while (list != NULL) {
425 HeapRegion* next = list->get_next_young_region();
426 list->set_next_young_region(NULL);
427 list->uninstall_surv_rate_group();
428 // This is called before a Full GC and all the non-empty /
429 // non-humongous regions at the end of the Full GC will end up as
430 // old anyway.
431 list->set_old();
432 list = next;
433 }
434 }
435
436 void YoungList::empty_list() {
437 assert(check_list_well_formed(), "young list should be well formed");
438
439 empty_list(_head);
440 _head = NULL;
441 _length = 0;
442
443 empty_list(_survivor_head);
444 _survivor_head = NULL;
445 _survivor_tail = NULL;
446 _survivor_length = 0;
447
448 _last_sampled_rs_lengths = 0;
449
450 assert(check_list_empty(false), "just making sure...");
451 }
452
453 bool YoungList::check_list_well_formed() {
454 bool ret = true;
455
456 uint length = 0;
457 HeapRegion* curr = _head;
458 HeapRegion* last = NULL;
459 while (curr != NULL) {
460 if (!curr->is_young()) {
461 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
462 "incorrectly tagged (y: %d, surv: %d)",
463 p2i(curr->bottom()), p2i(curr->end()),
464 curr->is_young(), curr->is_survivor());
465 ret = false;
466 }
467 ++length;
468 last = curr;
469 curr = curr->get_next_young_region();
470 }
471 ret = ret && (length == _length);
472
473 if (!ret) {
474 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
475 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
476 length, _length);
477 }
478
479 return ret;
480 }
481
482 bool YoungList::check_list_empty(bool check_sample) {
483 bool ret = true;
484
485 if (_length != 0) {
486 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
487 _length);
488 ret = false;
489 }
490 if (check_sample && _last_sampled_rs_lengths != 0) {
491 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
492 ret = false;
493 }
494 if (_head != NULL) {
495 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
496 ret = false;
497 }
498 if (!ret) {
499 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
500 }
501
502 return ret;
503 }
504
505 void
506 YoungList::rs_length_sampling_init() {
507 _sampled_rs_lengths = 0;
508 _curr = _head;
509 }
510
511 bool
512 YoungList::rs_length_sampling_more() {
513 return _curr != NULL;
514 }
515
516 void
517 YoungList::rs_length_sampling_next() {
518 assert( _curr != NULL, "invariant" );
519 size_t rs_length = _curr->rem_set()->occupied();
520
521 _sampled_rs_lengths += rs_length;
522
523 // The current region may not yet have been added to the
524 // incremental collection set (it gets added when it is
525 // retired as the current allocation region).
526 if (_curr->in_collection_set()) {
527 // Update the collection set policy information for this region
528 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
529 }
530
531 _curr = _curr->get_next_young_region();
532 if (_curr == NULL) {
533 _last_sampled_rs_lengths = _sampled_rs_lengths;
534 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
535 }
536 }
537
538 void
539 YoungList::reset_auxilary_lists() {
540 guarantee( is_empty(), "young list should be empty" );
541 assert(check_list_well_formed(), "young list should be well formed");
542
543 // Add survivor regions to SurvRateGroup.
544 _g1h->g1_policy()->note_start_adding_survivor_regions();
545 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
546
547 int young_index_in_cset = 0;
548 for (HeapRegion* curr = _survivor_head;
549 curr != NULL;
550 curr = curr->get_next_young_region()) {
551 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
552
553 // The region is a non-empty survivor so let's add it to
554 // the incremental collection set for the next evacuation
555 // pause.
556 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
557 young_index_in_cset += 1;
558 }
559 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
560 _g1h->g1_policy()->note_stop_adding_survivor_regions();
561
562 _head = _survivor_head;
563 _length = _survivor_length;
564 if (_survivor_head != NULL) {
565 assert(_survivor_tail != NULL, "cause it shouldn't be");
566 assert(_survivor_length > 0, "invariant");
567 _survivor_tail->set_next_young_region(NULL);
568 }
569
570 // Don't clear the survivor list handles until the start of
571 // the next evacuation pause - we need it in order to re-tag
572 // the survivor regions from this evacuation pause as 'young'
573 // at the start of the next.
574
575 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
576
577 assert(check_list_well_formed(), "young list should be well formed");
578 }
579
580 void YoungList::print() {
581 HeapRegion* lists[] = {_head, _survivor_head};
582 const char* names[] = {"YOUNG", "SURVIVOR"};
583
584 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
585 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
586 HeapRegion *curr = lists[list];
587 if (curr == NULL)
588 gclog_or_tty->print_cr(" empty");
589 while (curr != NULL) {
590 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
591 HR_FORMAT_PARAMS(curr),
592 p2i(curr->prev_top_at_mark_start()),
593 p2i(curr->next_top_at_mark_start()),
594 curr->age_in_surv_rate_group_cond());
595 curr = curr->get_next_young_region();
596 }
597 }
598
599 gclog_or_tty->cr();
600 }
601
602 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
603 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
604 }
605
606 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
607 // The from card cache is not the memory that is actually committed. So we cannot
608 // take advantage of the zero_filled parameter.
609 reset_from_card_cache(start_idx, num_regions);
610 }
611
612 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
613 {
614 // Claim the right to put the region on the dirty cards region list
615 // by installing a self pointer.
616 HeapRegion* next = hr->get_next_dirty_cards_region();
617 if (next == NULL) {
618 HeapRegion* res = (HeapRegion*)
619 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
620 NULL);
621 if (res == NULL) {
622 HeapRegion* head;
623 do {
624 // Put the region to the dirty cards region list.
625 head = _dirty_cards_region_list;
626 next = (HeapRegion*)
627 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
628 if (next == head) {
629 assert(hr->get_next_dirty_cards_region() == hr,
630 "hr->get_next_dirty_cards_region() != hr");
631 if (next == NULL) {
632 // The last region in the list points to itself.
633 hr->set_next_dirty_cards_region(hr);
634 } else {
635 hr->set_next_dirty_cards_region(next);
636 }
637 }
638 } while (next != head);
639 }
640 }
641 }
642
643 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
644 {
645 HeapRegion* head;
646 HeapRegion* hr;
647 do {
648 head = _dirty_cards_region_list;
649 if (head == NULL) {
650 return NULL;
651 }
652 HeapRegion* new_head = head->get_next_dirty_cards_region();
653 if (head == new_head) {
654 // The last region.
655 new_head = NULL;
656 }
657 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
658 head);
659 } while (hr != head);
660 assert(hr != NULL, "invariant");
661 hr->set_next_dirty_cards_region(NULL);
662 return hr;
663 }
664
665 // Returns true if the reference points to an object that
666 // can move in an incremental collection.
667 bool G1CollectedHeap::is_scavengable(const void* p) {
668 HeapRegion* hr = heap_region_containing(p);
669 return !hr->is_pinned();
670 }
671
672 // Private methods.
673
674 HeapRegion*
675 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
676 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
677 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
678 if (!_secondary_free_list.is_empty()) {
679 if (G1ConcRegionFreeingVerbose) {
680 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
681 "secondary_free_list has %u entries",
682 _secondary_free_list.length());
683 }
684 // It looks as if there are free regions available on the
685 // secondary_free_list. Let's move them to the free_list and try
686 // again to allocate from it.
687 append_secondary_free_list();
688
689 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
690 "empty we should have moved at least one entry to the free_list");
691 HeapRegion* res = _hrm.allocate_free_region(is_old);
692 if (G1ConcRegionFreeingVerbose) {
693 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
694 "allocated " HR_FORMAT " from secondary_free_list",
695 HR_FORMAT_PARAMS(res));
696 }
697 return res;
698 }
699
700 // Wait here until we get notified either when (a) there are no
701 // more free regions coming or (b) some regions have been moved on
702 // the secondary_free_list.
703 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
704 }
705
706 if (G1ConcRegionFreeingVerbose) {
707 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
708 "could not allocate from secondary_free_list");
709 }
710 return NULL;
711 }
712
713 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
714 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
715 "the only time we use this to allocate a humongous region is "
716 "when we are allocating a single humongous region");
717
718 HeapRegion* res;
719 if (G1StressConcRegionFreeing) {
720 if (!_secondary_free_list.is_empty()) {
721 if (G1ConcRegionFreeingVerbose) {
722 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
723 "forced to look at the secondary_free_list");
724 }
725 res = new_region_try_secondary_free_list(is_old);
726 if (res != NULL) {
727 return res;
728 }
729 }
730 }
731
732 res = _hrm.allocate_free_region(is_old);
733
734 if (res == NULL) {
735 if (G1ConcRegionFreeingVerbose) {
736 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
737 "res == NULL, trying the secondary_free_list");
738 }
739 res = new_region_try_secondary_free_list(is_old);
740 }
741 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
742 // Currently, only attempts to allocate GC alloc regions set
743 // do_expand to true. So, we should only reach here during a
744 // safepoint. If this assumption changes we might have to
745 // reconsider the use of _expand_heap_after_alloc_failure.
746 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
747
748 ergo_verbose1(ErgoHeapSizing,
749 "attempt heap expansion",
750 ergo_format_reason("region allocation request failed")
751 ergo_format_byte("allocation request"),
752 word_size * HeapWordSize);
753 if (expand(word_size * HeapWordSize)) {
754 // Given that expand() succeeded in expanding the heap, and we
755 // always expand the heap by an amount aligned to the heap
756 // region size, the free list should in theory not be empty.
757 // In either case allocate_free_region() will check for NULL.
758 res = _hrm.allocate_free_region(is_old);
759 } else {
760 _expand_heap_after_alloc_failure = false;
761 }
762 }
763 return res;
764 }
765
766 HeapWord*
767 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
768 uint num_regions,
769 size_t word_size,
770 AllocationContext_t context) {
771 assert(first != G1_NO_HRM_INDEX, "pre-condition");
772 assert(is_humongous(word_size), "word_size should be humongous");
773 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
774
775 // Index of last region in the series + 1.
776 uint last = first + num_regions;
777
778 // We need to initialize the region(s) we just discovered. This is
779 // a bit tricky given that it can happen concurrently with
780 // refinement threads refining cards on these regions and
781 // potentially wanting to refine the BOT as they are scanning
782 // those cards (this can happen shortly after a cleanup; see CR
783 // 6991377). So we have to set up the region(s) carefully and in
784 // a specific order.
785
786 // The word size sum of all the regions we will allocate.
787 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
788 assert(word_size <= word_size_sum, "sanity");
789
790 // This will be the "starts humongous" region.
791 HeapRegion* first_hr = region_at(first);
792 // The header of the new object will be placed at the bottom of
793 // the first region.
794 HeapWord* new_obj = first_hr->bottom();
795 // This will be the new end of the first region in the series that
796 // should also match the end of the last region in the series.
797 HeapWord* new_end = new_obj + word_size_sum;
798 // This will be the new top of the first region that will reflect
799 // this allocation.
800 HeapWord* new_top = new_obj + word_size;
801
802 // First, we need to zero the header of the space that we will be
803 // allocating. When we update top further down, some refinement
804 // threads might try to scan the region. By zeroing the header we
805 // ensure that any thread that will try to scan the region will
806 // come across the zero klass word and bail out.
807 //
808 // NOTE: It would not have been correct to have used
809 // CollectedHeap::fill_with_object() and make the space look like
810 // an int array. The thread that is doing the allocation will
811 // later update the object header to a potentially different array
812 // type and, for a very short period of time, the klass and length
813 // fields will be inconsistent. This could cause a refinement
814 // thread to calculate the object size incorrectly.
815 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
816
817 // We will set up the first region as "starts humongous". This
818 // will also update the BOT covering all the regions to reflect
819 // that there is a single object that starts at the bottom of the
820 // first region.
821 first_hr->set_starts_humongous(new_top, new_end);
822 first_hr->set_allocation_context(context);
823 // Then, if there are any, we will set up the "continues
824 // humongous" regions.
825 HeapRegion* hr = NULL;
826 for (uint i = first + 1; i < last; ++i) {
827 hr = region_at(i);
828 hr->set_continues_humongous(first_hr);
829 hr->set_allocation_context(context);
830 }
831 // If we have "continues humongous" regions (hr != NULL), then the
832 // end of the last one should match new_end.
833 assert(hr == NULL || hr->end() == new_end, "sanity");
834
835 // Up to this point no concurrent thread would have been able to
836 // do any scanning on any region in this series. All the top
837 // fields still point to bottom, so the intersection between
838 // [bottom,top] and [card_start,card_end] will be empty. Before we
839 // update the top fields, we'll do a storestore to make sure that
840 // no thread sees the update to top before the zeroing of the
841 // object header and the BOT initialization.
842 OrderAccess::storestore();
843
844 // Now that the BOT and the object header have been initialized,
845 // we can update top of the "starts humongous" region.
846 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
847 "new_top should be in this region");
848 first_hr->set_top(new_top);
849 if (_hr_printer.is_active()) {
850 HeapWord* bottom = first_hr->bottom();
851 HeapWord* end = first_hr->orig_end();
852 if ((first + 1) == last) {
853 // the series has a single humongous region
854 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
855 } else {
856 // the series has more than one humongous regions
857 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
858 }
859 }
860
861 // Now, we will update the top fields of the "continues humongous"
862 // regions. The reason we need to do this is that, otherwise,
863 // these regions would look empty and this will confuse parts of
864 // G1. For example, the code that looks for a consecutive number
865 // of empty regions will consider them empty and try to
866 // re-allocate them. We can extend is_empty() to also include
867 // !is_continues_humongous(), but it is easier to just update the top
868 // fields here. The way we set top for all regions (i.e., top ==
869 // end for all regions but the last one, top == new_top for the
870 // last one) is actually used when we will free up the humongous
871 // region in free_humongous_region().
872 hr = NULL;
873 for (uint i = first + 1; i < last; ++i) {
874 hr = region_at(i);
875 if ((i + 1) == last) {
876 // last continues humongous region
877 assert(hr->bottom() < new_top && new_top <= hr->end(),
878 "new_top should fall on this region");
879 hr->set_top(new_top);
880 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
881 } else {
882 // not last one
883 assert(new_top > hr->end(), "new_top should be above this region");
884 hr->set_top(hr->end());
885 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
886 }
887 }
888 // If we have continues humongous regions (hr != NULL), then the
889 // end of the last one should match new_end and its top should
890 // match new_top.
891 assert(hr == NULL ||
892 (hr->end() == new_end && hr->top() == new_top), "sanity");
893 check_bitmaps("Humongous Region Allocation", first_hr);
894
895 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
896 increase_used(first_hr->used());
897 _humongous_set.add(first_hr);
898
899 return new_obj;
900 }
901
902 // If could fit into free regions w/o expansion, try.
903 // Otherwise, if can expand, do so.
904 // Otherwise, if using ex regions might help, try with ex given back.
905 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
906 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
907
908 verify_region_sets_optional();
909
910 uint first = G1_NO_HRM_INDEX;
911 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
912
913 if (obj_regions == 1) {
914 // Only one region to allocate, try to use a fast path by directly allocating
915 // from the free lists. Do not try to expand here, we will potentially do that
916 // later.
917 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
918 if (hr != NULL) {
919 first = hr->hrm_index();
920 }
921 } else {
922 // We can't allocate humongous regions spanning more than one region while
923 // cleanupComplete() is running, since some of the regions we find to be
924 // empty might not yet be added to the free list. It is not straightforward
925 // to know in which list they are on so that we can remove them. We only
926 // need to do this if we need to allocate more than one region to satisfy the
927 // current humongous allocation request. If we are only allocating one region
928 // we use the one-region region allocation code (see above), that already
929 // potentially waits for regions from the secondary free list.
930 wait_while_free_regions_coming();
931 append_secondary_free_list_if_not_empty_with_lock();
932
933 // Policy: Try only empty regions (i.e. already committed first). Maybe we
934 // are lucky enough to find some.
935 first = _hrm.find_contiguous_only_empty(obj_regions);
936 if (first != G1_NO_HRM_INDEX) {
937 _hrm.allocate_free_regions_starting_at(first, obj_regions);
938 }
939 }
940
941 if (first == G1_NO_HRM_INDEX) {
942 // Policy: We could not find enough regions for the humongous object in the
943 // free list. Look through the heap to find a mix of free and uncommitted regions.
944 // If so, try expansion.
945 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
946 if (first != G1_NO_HRM_INDEX) {
947 // We found something. Make sure these regions are committed, i.e. expand
948 // the heap. Alternatively we could do a defragmentation GC.
949 ergo_verbose1(ErgoHeapSizing,
950 "attempt heap expansion",
951 ergo_format_reason("humongous allocation request failed")
952 ergo_format_byte("allocation request"),
953 word_size * HeapWordSize);
954
955 _hrm.expand_at(first, obj_regions);
956 g1_policy()->record_new_heap_size(num_regions());
957
958 #ifdef ASSERT
959 for (uint i = first; i < first + obj_regions; ++i) {
960 HeapRegion* hr = region_at(i);
961 assert(hr->is_free(), "sanity");
962 assert(hr->is_empty(), "sanity");
963 assert(is_on_master_free_list(hr), "sanity");
964 }
965 #endif
966 _hrm.allocate_free_regions_starting_at(first, obj_regions);
967 } else {
968 // Policy: Potentially trigger a defragmentation GC.
969 }
970 }
971
972 HeapWord* result = NULL;
973 if (first != G1_NO_HRM_INDEX) {
974 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
975 word_size, context);
976 assert(result != NULL, "it should always return a valid result");
977
978 // A successful humongous object allocation changes the used space
979 // information of the old generation so we need to recalculate the
980 // sizes and update the jstat counters here.
981 g1mm()->update_sizes();
982 }
983
984 verify_region_sets_optional();
985
986 return result;
987 }
988
989 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
990 assert_heap_not_locked_and_not_at_safepoint();
991 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
992
993 uint dummy_gc_count_before;
994 uint dummy_gclocker_retry_count = 0;
995 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
996 }
997
998 HeapWord*
999 G1CollectedHeap::mem_allocate(size_t word_size,
1000 bool* gc_overhead_limit_was_exceeded) {
1001 assert_heap_not_locked_and_not_at_safepoint();
1002
1003 // Loop until the allocation is satisfied, or unsatisfied after GC.
1004 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
1005 uint gc_count_before;
1006
1007 HeapWord* result = NULL;
1008 if (!is_humongous(word_size)) {
1009 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
1010 } else {
1011 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
1012 }
1013 if (result != NULL) {
1014 return result;
1015 }
1016
1017 // Create the garbage collection operation...
1018 VM_G1CollectForAllocation op(gc_count_before, word_size);
1019 op.set_allocation_context(AllocationContext::current());
1020
1021 // ...and get the VM thread to execute it.
1022 VMThread::execute(&op);
1023
1024 if (op.prologue_succeeded() && op.pause_succeeded()) {
1025 // If the operation was successful we'll return the result even
1026 // if it is NULL. If the allocation attempt failed immediately
1027 // after a Full GC, it's unlikely we'll be able to allocate now.
1028 HeapWord* result = op.result();
1029 if (result != NULL && !is_humongous(word_size)) {
1030 // Allocations that take place on VM operations do not do any
1031 // card dirtying and we have to do it here. We only have to do
1032 // this for non-humongous allocations, though.
1033 dirty_young_block(result, word_size);
1034 }
1035 return result;
1036 } else {
1037 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
1038 return NULL;
1039 }
1040 assert(op.result() == NULL,
1041 "the result should be NULL if the VM op did not succeed");
1042 }
1043
1044 // Give a warning if we seem to be looping forever.
1045 if ((QueuedAllocationWarningCount > 0) &&
1046 (try_count % QueuedAllocationWarningCount == 0)) {
1047 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
1048 }
1049 }
1050
1051 ShouldNotReachHere();
1052 return NULL;
1053 }
1054
1055 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
1056 AllocationContext_t context,
1057 uint* gc_count_before_ret,
1058 uint* gclocker_retry_count_ret) {
1059 // Make sure you read the note in attempt_allocation_humongous().
1060
1061 assert_heap_not_locked_and_not_at_safepoint();
1062 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
1063 "be called for humongous allocation requests");
1064
1065 // We should only get here after the first-level allocation attempt
1066 // (attempt_allocation()) failed to allocate.
1067
1068 // We will loop until a) we manage to successfully perform the
1069 // allocation or b) we successfully schedule a collection which
1070 // fails to perform the allocation. b) is the only case when we'll
1071 // return NULL.
1072 HeapWord* result = NULL;
1073 for (int try_count = 1; /* we'll return */; try_count += 1) {
1074 bool should_try_gc;
1075 uint gc_count_before;
1076
1077 {
1078 MutexLockerEx x(Heap_lock);
1079 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1080 false /* bot_updates */);
1081 if (result != NULL) {
1082 return result;
1083 }
1084
1085 // If we reach here, attempt_allocation_locked() above failed to
1086 // allocate a new region. So the mutator alloc region should be NULL.
1087 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
1088
1089 if (GC_locker::is_active_and_needs_gc()) {
1090 if (g1_policy()->can_expand_young_list()) {
1091 // No need for an ergo verbose message here,
1092 // can_expand_young_list() does this when it returns true.
1093 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
1094 false /* bot_updates */);
1095 if (result != NULL) {
1096 return result;
1097 }
1098 }
1099 should_try_gc = false;
1100 } else {
1101 // The GCLocker may not be active but the GCLocker initiated
1102 // GC may not yet have been performed (GCLocker::needs_gc()
1103 // returns true). In this case we do not try this GC and
1104 // wait until the GCLocker initiated GC is performed, and
1105 // then retry the allocation.
1106 if (GC_locker::needs_gc()) {
1107 should_try_gc = false;
1108 } else {
1109 // Read the GC count while still holding the Heap_lock.
1110 gc_count_before = total_collections();
1111 should_try_gc = true;
1112 }
1113 }
1114 }
1115
1116 if (should_try_gc) {
1117 bool succeeded;
1118 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1119 GCCause::_g1_inc_collection_pause);
1120 if (result != NULL) {
1121 assert(succeeded, "only way to get back a non-NULL result");
1122 return result;
1123 }
1124
1125 if (succeeded) {
1126 // If we get here we successfully scheduled a collection which
1127 // failed to allocate. No point in trying to allocate
1128 // further. We'll just return NULL.
1129 MutexLockerEx x(Heap_lock);
1130 *gc_count_before_ret = total_collections();
1131 return NULL;
1132 }
1133 } else {
1134 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1135 MutexLockerEx x(Heap_lock);
1136 *gc_count_before_ret = total_collections();
1137 return NULL;
1138 }
1139 // The GCLocker is either active or the GCLocker initiated
1140 // GC has not yet been performed. Stall until it is and
1141 // then retry the allocation.
1142 GC_locker::stall_until_clear();
1143 (*gclocker_retry_count_ret) += 1;
1144 }
1145
1146 // We can reach here if we were unsuccessful in scheduling a
1147 // collection (because another thread beat us to it) or if we were
1148 // stalled due to the GC locker. In either can we should retry the
1149 // allocation attempt in case another thread successfully
1150 // performed a collection and reclaimed enough space. We do the
1151 // first attempt (without holding the Heap_lock) here and the
1152 // follow-on attempt will be at the start of the next loop
1153 // iteration (after taking the Heap_lock).
1154 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
1155 false /* bot_updates */);
1156 if (result != NULL) {
1157 return result;
1158 }
1159
1160 // Give a warning if we seem to be looping forever.
1161 if ((QueuedAllocationWarningCount > 0) &&
1162 (try_count % QueuedAllocationWarningCount == 0)) {
1163 warning("G1CollectedHeap::attempt_allocation_slow() "
1164 "retries %d times", try_count);
1165 }
1166 }
1167
1168 ShouldNotReachHere();
1169 return NULL;
1170 }
1171
1172 void G1CollectedHeap::begin_archive_alloc_range() {
1173 assert_at_safepoint(true /* should_be_vm_thread */);
1174 if (_archive_allocator == NULL) {
1175 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
1176 }
1177 }
1178
1179 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
1180 // Allocations in archive regions cannot be of a size that would be considered
1181 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
1182 // may be different at archive-restore time.
1183 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
1184 }
1185
1186 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
1187 assert_at_safepoint(true /* should_be_vm_thread */);
1188 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
1189 if (is_archive_alloc_too_large(word_size)) {
1190 return NULL;
1191 }
1192 return _archive_allocator->archive_mem_allocate(word_size);
1193 }
1194
1195 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
1196 size_t end_alignment_in_bytes) {
1197 assert_at_safepoint(true /* should_be_vm_thread */);
1198 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
1199
1200 // Call complete_archive to do the real work, filling in the MemRegion
1201 // array with the archive regions.
1202 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
1203 delete _archive_allocator;
1204 _archive_allocator = NULL;
1205 }
1206
1207 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
1208 assert(ranges != NULL, "MemRegion array NULL");
1209 assert(count != 0, "No MemRegions provided");
1210 MemRegion reserved = _hrm.reserved();
1211 for (size_t i = 0; i < count; i++) {
1212 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
1213 return false;
1214 }
1215 }
1216 return true;
1217 }
1218
1219 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
1220 assert(ranges != NULL, "MemRegion array NULL");
1221 assert(count != 0, "No MemRegions provided");
1222 MutexLockerEx x(Heap_lock);
1223
1224 MemRegion reserved = _hrm.reserved();
1225 HeapWord* prev_last_addr = NULL;
1226 HeapRegion* prev_last_region = NULL;
1227
1228 // Temporarily disable pretouching of heap pages. This interface is used
1229 // when mmap'ing archived heap data in, so pre-touching is wasted.
1230 FlagSetting fs(AlwaysPreTouch, false);
1231
1232 // Enable archive object checking in G1MarkSweep. We have to let it know
1233 // about each archive range, so that objects in those ranges aren't marked.
1234 G1MarkSweep::enable_archive_object_check();
1235
1236 // For each specified MemRegion range, allocate the corresponding G1
1237 // regions and mark them as archive regions. We expect the ranges in
1238 // ascending starting address order, without overlap.
1239 for (size_t i = 0; i < count; i++) {
1240 MemRegion curr_range = ranges[i];
1241 HeapWord* start_address = curr_range.start();
1242 size_t word_size = curr_range.word_size();
1243 HeapWord* last_address = curr_range.last();
1244 size_t commits = 0;
1245
1246 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
1247 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1248 p2i(start_address), p2i(last_address)));
1249 guarantee(start_address > prev_last_addr,
1250 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1251 p2i(start_address), p2i(prev_last_addr)));
1252 prev_last_addr = last_address;
1253
1254 // Check for ranges that start in the same G1 region in which the previous
1255 // range ended, and adjust the start address so we don't try to allocate
1256 // the same region again. If the current range is entirely within that
1257 // region, skip it, just adjusting the recorded top.
1258 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1259 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
1260 start_address = start_region->end();
1261 if (start_address > last_address) {
1262 increase_used(word_size * HeapWordSize);
1263 start_region->set_top(last_address + 1);
1264 continue;
1265 }
1266 start_region->set_top(start_address);
1267 curr_range = MemRegion(start_address, last_address + 1);
1268 start_region = _hrm.addr_to_region(start_address);
1269 }
1270
1271 // Perform the actual region allocation, exiting if it fails.
1272 // Then note how much new space we have allocated.
1273 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1274 return false;
1275 }
1276 increase_used(word_size * HeapWordSize);
1277 if (commits != 0) {
1278 ergo_verbose1(ErgoHeapSizing,
1279 "attempt heap expansion",
1280 ergo_format_reason("allocate archive regions")
1281 ergo_format_byte("total size"),
1282 HeapRegion::GrainWords * HeapWordSize * commits);
1283 }
1284
1285 // Mark each G1 region touched by the range as archive, add it to the old set,
1286 // and set the allocation context and top.
1287 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1288 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1289 prev_last_region = last_region;
1290
1291 while (curr_region != NULL) {
1292 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1293 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1294 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1295 curr_region->set_allocation_context(AllocationContext::system());
1296 curr_region->set_archive();
1297 _old_set.add(curr_region);
1298 if (curr_region != last_region) {
1299 curr_region->set_top(curr_region->end());
1300 curr_region = _hrm.next_region_in_heap(curr_region);
1301 } else {
1302 curr_region->set_top(last_address + 1);
1303 curr_region = NULL;
1304 }
1305 }
1306
1307 // Notify mark-sweep of the archive range.
1308 G1MarkSweep::mark_range_archive(curr_range);
1309 }
1310 return true;
1311 }
1312
1313 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1314 assert(ranges != NULL, "MemRegion array NULL");
1315 assert(count != 0, "No MemRegions provided");
1316 MemRegion reserved = _hrm.reserved();
1317 HeapWord *prev_last_addr = NULL;
1318 HeapRegion* prev_last_region = NULL;
1319
1320 // For each MemRegion, create filler objects, if needed, in the G1 regions
1321 // that contain the address range. The address range actually within the
1322 // MemRegion will not be modified. That is assumed to have been initialized
1323 // elsewhere, probably via an mmap of archived heap data.
1324 MutexLockerEx x(Heap_lock);
1325 for (size_t i = 0; i < count; i++) {
1326 HeapWord* start_address = ranges[i].start();
1327 HeapWord* last_address = ranges[i].last();
1328
1329 assert(reserved.contains(start_address) && reserved.contains(last_address),
1330 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1331 p2i(start_address), p2i(last_address)));
1332 assert(start_address > prev_last_addr,
1333 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1334 p2i(start_address), p2i(prev_last_addr)));
1335
1336 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1337 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1338 HeapWord* bottom_address = start_region->bottom();
1339
1340 // Check for a range beginning in the same region in which the
1341 // previous one ended.
1342 if (start_region == prev_last_region) {
1343 bottom_address = prev_last_addr + 1;
1344 }
1345
1346 // Verify that the regions were all marked as archive regions by
1347 // alloc_archive_regions.
1348 HeapRegion* curr_region = start_region;
1349 while (curr_region != NULL) {
1350 guarantee(curr_region->is_archive(),
1351 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1352 if (curr_region != last_region) {
1353 curr_region = _hrm.next_region_in_heap(curr_region);
1354 } else {
1355 curr_region = NULL;
1356 }
1357 }
1358
1359 prev_last_addr = last_address;
1360 prev_last_region = last_region;
1361
1362 // Fill the memory below the allocated range with dummy object(s),
1363 // if the region bottom does not match the range start, or if the previous
1364 // range ended within the same G1 region, and there is a gap.
1365 if (start_address != bottom_address) {
1366 size_t fill_size = pointer_delta(start_address, bottom_address);
1367 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1368 increase_used(fill_size * HeapWordSize);
1369 }
1370 }
1371 }
1372
1373 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1374 uint* gc_count_before_ret,
1375 uint* gclocker_retry_count_ret) {
1376 // The structure of this method has a lot of similarities to
1377 // attempt_allocation_slow(). The reason these two were not merged
1378 // into a single one is that such a method would require several "if
1379 // allocation is not humongous do this, otherwise do that"
1380 // conditional paths which would obscure its flow. In fact, an early
1381 // version of this code did use a unified method which was harder to
1382 // follow and, as a result, it had subtle bugs that were hard to
1383 // track down. So keeping these two methods separate allows each to
1384 // be more readable. It will be good to keep these two in sync as
1385 // much as possible.
1386
1387 assert_heap_not_locked_and_not_at_safepoint();
1388 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1389 "should only be called for humongous allocations");
1390
1391 // Humongous objects can exhaust the heap quickly, so we should check if we
1392 // need to start a marking cycle at each humongous object allocation. We do
1393 // the check before we do the actual allocation. The reason for doing it
1394 // before the allocation is that we avoid having to keep track of the newly
1395 // allocated memory while we do a GC.
1396 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1397 word_size)) {
1398 collect(GCCause::_g1_humongous_allocation);
1399 }
1400
1401 // We will loop until a) we manage to successfully perform the
1402 // allocation or b) we successfully schedule a collection which
1403 // fails to perform the allocation. b) is the only case when we'll
1404 // return NULL.
1405 HeapWord* result = NULL;
1406 for (int try_count = 1; /* we'll return */; try_count += 1) {
1407 bool should_try_gc;
1408 uint gc_count_before;
1409
1410 {
1411 MutexLockerEx x(Heap_lock);
1412
1413 // Given that humongous objects are not allocated in young
1414 // regions, we'll first try to do the allocation without doing a
1415 // collection hoping that there's enough space in the heap.
1416 result = humongous_obj_allocate(word_size, AllocationContext::current());
1417 if (result != NULL) {
1418 return result;
1419 }
1420
1421 if (GC_locker::is_active_and_needs_gc()) {
1422 should_try_gc = false;
1423 } else {
1424 // The GCLocker may not be active but the GCLocker initiated
1425 // GC may not yet have been performed (GCLocker::needs_gc()
1426 // returns true). In this case we do not try this GC and
1427 // wait until the GCLocker initiated GC is performed, and
1428 // then retry the allocation.
1429 if (GC_locker::needs_gc()) {
1430 should_try_gc = false;
1431 } else {
1432 // Read the GC count while still holding the Heap_lock.
1433 gc_count_before = total_collections();
1434 should_try_gc = true;
1435 }
1436 }
1437 }
1438
1439 if (should_try_gc) {
1440 // If we failed to allocate the humongous object, we should try to
1441 // do a collection pause (if we're allowed) in case it reclaims
1442 // enough space for the allocation to succeed after the pause.
1443
1444 bool succeeded;
1445 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1446 GCCause::_g1_humongous_allocation);
1447 if (result != NULL) {
1448 assert(succeeded, "only way to get back a non-NULL result");
1449 return result;
1450 }
1451
1452 if (succeeded) {
1453 // If we get here we successfully scheduled a collection which
1454 // failed to allocate. No point in trying to allocate
1455 // further. We'll just return NULL.
1456 MutexLockerEx x(Heap_lock);
1457 *gc_count_before_ret = total_collections();
1458 return NULL;
1459 }
1460 } else {
1461 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1462 MutexLockerEx x(Heap_lock);
1463 *gc_count_before_ret = total_collections();
1464 return NULL;
1465 }
1466 // The GCLocker is either active or the GCLocker initiated
1467 // GC has not yet been performed. Stall until it is and
1468 // then retry the allocation.
1469 GC_locker::stall_until_clear();
1470 (*gclocker_retry_count_ret) += 1;
1471 }
1472
1473 // We can reach here if we were unsuccessful in scheduling a
1474 // collection (because another thread beat us to it) or if we were
1475 // stalled due to the GC locker. In either can we should retry the
1476 // allocation attempt in case another thread successfully
1477 // performed a collection and reclaimed enough space. Give a
1478 // warning if we seem to be looping forever.
1479
1480 if ((QueuedAllocationWarningCount > 0) &&
1481 (try_count % QueuedAllocationWarningCount == 0)) {
1482 warning("G1CollectedHeap::attempt_allocation_humongous() "
1483 "retries %d times", try_count);
1484 }
1485 }
1486
1487 ShouldNotReachHere();
1488 return NULL;
1489 }
1490
1491 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1492 AllocationContext_t context,
1493 bool expect_null_mutator_alloc_region) {
1494 assert_at_safepoint(true /* should_be_vm_thread */);
1495 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1496 !expect_null_mutator_alloc_region,
1497 "the current alloc region was unexpectedly found to be non-NULL");
1498
1499 if (!is_humongous(word_size)) {
1500 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1501 false /* bot_updates */);
1502 } else {
1503 HeapWord* result = humongous_obj_allocate(word_size, context);
1504 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1505 collector_state()->set_initiate_conc_mark_if_possible(true);
1506 }
1507 return result;
1508 }
1509
1510 ShouldNotReachHere();
1511 }
1512
1513 class PostMCRemSetClearClosure: public HeapRegionClosure {
1514 G1CollectedHeap* _g1h;
1515 ModRefBarrierSet* _mr_bs;
1516 public:
1517 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1518 _g1h(g1h), _mr_bs(mr_bs) {}
1519
1520 bool doHeapRegion(HeapRegion* r) {
1521 HeapRegionRemSet* hrrs = r->rem_set();
1522
1523 if (r->is_continues_humongous()) {
1524 // We'll assert that the strong code root list and RSet is empty
1525 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1526 assert(hrrs->occupied() == 0, "RSet should be empty");
1527 return false;
1528 }
1529
1530 _g1h->reset_gc_time_stamps(r);
1531 hrrs->clear();
1532 // You might think here that we could clear just the cards
1533 // corresponding to the used region. But no: if we leave a dirty card
1534 // in a region we might allocate into, then it would prevent that card
1535 // from being enqueued, and cause it to be missed.
1536 // Re: the performance cost: we shouldn't be doing full GC anyway!
1537 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1538
1539 return false;
1540 }
1541 };
1542
1543 void G1CollectedHeap::clear_rsets_post_compaction() {
1544 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1545 heap_region_iterate(&rs_clear);
1546 }
1547
1548 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1549 G1CollectedHeap* _g1h;
1550 UpdateRSOopClosure _cl;
1551 public:
1552 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1553 _cl(g1->g1_rem_set(), worker_i),
1554 _g1h(g1)
1555 { }
1556
1557 bool doHeapRegion(HeapRegion* r) {
1558 if (!r->is_continues_humongous()) {
1559 _cl.set_from(r);
1560 r->oop_iterate(&_cl);
1561 }
1562 return false;
1563 }
1564 };
1565
1566 class ParRebuildRSTask: public AbstractGangTask {
1567 G1CollectedHeap* _g1;
1568 HeapRegionClaimer _hrclaimer;
1569
1570 public:
1571 ParRebuildRSTask(G1CollectedHeap* g1) :
1572 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1573
1574 void work(uint worker_id) {
1575 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1576 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1577 }
1578 };
1579
1580 class PostCompactionPrinterClosure: public HeapRegionClosure {
1581 private:
1582 G1HRPrinter* _hr_printer;
1583 public:
1584 bool doHeapRegion(HeapRegion* hr) {
1585 assert(!hr->is_young(), "not expecting to find young regions");
1586 if (hr->is_free()) {
1587 // We only generate output for non-empty regions.
1588 } else if (hr->is_starts_humongous()) {
1589 if (hr->region_num() == 1) {
1590 // single humongous region
1591 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1592 } else {
1593 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1594 }
1595 } else if (hr->is_continues_humongous()) {
1596 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1597 } else if (hr->is_archive()) {
1598 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1599 } else if (hr->is_old()) {
1600 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1601 } else {
1602 ShouldNotReachHere();
1603 }
1604 return false;
1605 }
1606
1607 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1608 : _hr_printer(hr_printer) { }
1609 };
1610
1611 void G1CollectedHeap::print_hrm_post_compaction() {
1612 PostCompactionPrinterClosure cl(hr_printer());
1613 heap_region_iterate(&cl);
1614 }
1615
1616 bool G1CollectedHeap::do_collection(bool explicit_gc,
1617 bool clear_all_soft_refs,
1618 size_t word_size) {
1619 assert_at_safepoint(true /* should_be_vm_thread */);
1620
1621 if (GC_locker::check_active_before_gc()) {
1622 return false;
1623 }
1624
1625 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1626 gc_timer->register_gc_start();
1627
1628 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1629 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1630
1631 SvcGCMarker sgcm(SvcGCMarker::FULL);
1632 ResourceMark rm;
1633
1634 G1Log::update_level();
1635 print_heap_before_gc();
1636 trace_heap_before_gc(gc_tracer);
1637
1638 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1639
1640 verify_region_sets_optional();
1641
1642 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1643 collector_policy()->should_clear_all_soft_refs();
1644
1645 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1646
1647 {
1648 IsGCActiveMark x;
1649
1650 // Timing
1651 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1652 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1653
1654 {
1655 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1656 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1657 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1658
1659 g1_policy()->record_full_collection_start();
1660
1661 // Note: When we have a more flexible GC logging framework that
1662 // allows us to add optional attributes to a GC log record we
1663 // could consider timing and reporting how long we wait in the
1664 // following two methods.
1665 wait_while_free_regions_coming();
1666 // If we start the compaction before the CM threads finish
1667 // scanning the root regions we might trip them over as we'll
1668 // be moving objects / updating references. So let's wait until
1669 // they are done. By telling them to abort, they should complete
1670 // early.
1671 _cm->root_regions()->abort();
1672 _cm->root_regions()->wait_until_scan_finished();
1673 append_secondary_free_list_if_not_empty_with_lock();
1674
1675 gc_prologue(true);
1676 increment_total_collections(true /* full gc */);
1677 increment_old_marking_cycles_started();
1678
1679 assert(used() == recalculate_used(), "Should be equal");
1680
1681 verify_before_gc();
1682
1683 check_bitmaps("Full GC Start");
1684 pre_full_gc_dump(gc_timer);
1685
1686 COMPILER2_PRESENT(DerivedPointerTable::clear());
1687
1688 // Disable discovery and empty the discovered lists
1689 // for the CM ref processor.
1690 ref_processor_cm()->disable_discovery();
1691 ref_processor_cm()->abandon_partial_discovery();
1692 ref_processor_cm()->verify_no_references_recorded();
1693
1694 // Abandon current iterations of concurrent marking and concurrent
1695 // refinement, if any are in progress. We have to do this before
1696 // wait_until_scan_finished() below.
1697 concurrent_mark()->abort();
1698
1699 // Make sure we'll choose a new allocation region afterwards.
1700 _allocator->release_mutator_alloc_region();
1701 _allocator->abandon_gc_alloc_regions();
1702 g1_rem_set()->cleanupHRRS();
1703
1704 // We should call this after we retire any currently active alloc
1705 // regions so that all the ALLOC / RETIRE events are generated
1706 // before the start GC event.
1707 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1708
1709 // We may have added regions to the current incremental collection
1710 // set between the last GC or pause and now. We need to clear the
1711 // incremental collection set and then start rebuilding it afresh
1712 // after this full GC.
1713 abandon_collection_set(g1_policy()->inc_cset_head());
1714 g1_policy()->clear_incremental_cset();
1715 g1_policy()->stop_incremental_cset_building();
1716
1717 tear_down_region_sets(false /* free_list_only */);
1718 collector_state()->set_gcs_are_young(true);
1719
1720 // See the comments in g1CollectedHeap.hpp and
1721 // G1CollectedHeap::ref_processing_init() about
1722 // how reference processing currently works in G1.
1723
1724 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1725 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1726
1727 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1728 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1729
1730 ref_processor_stw()->enable_discovery();
1731 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1732
1733 // Do collection work
1734 {
1735 HandleMark hm; // Discard invalid handles created during gc
1736 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1737 }
1738
1739 assert(num_free_regions() == 0, "we should not have added any free regions");
1740 rebuild_region_sets(false /* free_list_only */);
1741
1742 // Enqueue any discovered reference objects that have
1743 // not been removed from the discovered lists.
1744 ref_processor_stw()->enqueue_discovered_references();
1745
1746 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1747
1748 MemoryService::track_memory_usage();
1749
1750 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1751 ref_processor_stw()->verify_no_references_recorded();
1752
1753 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1754 ClassLoaderDataGraph::purge();
1755 MetaspaceAux::verify_metrics();
1756
1757 // Note: since we've just done a full GC, concurrent
1758 // marking is no longer active. Therefore we need not
1759 // re-enable reference discovery for the CM ref processor.
1760 // That will be done at the start of the next marking cycle.
1761 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1762 ref_processor_cm()->verify_no_references_recorded();
1763
1764 reset_gc_time_stamp();
1765 // Since everything potentially moved, we will clear all remembered
1766 // sets, and clear all cards. Later we will rebuild remembered
1767 // sets. We will also reset the GC time stamps of the regions.
1768 clear_rsets_post_compaction();
1769 check_gc_time_stamps();
1770
1771 // Resize the heap if necessary.
1772 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1773
1774 if (_hr_printer.is_active()) {
1775 // We should do this after we potentially resize the heap so
1776 // that all the COMMIT / UNCOMMIT events are generated before
1777 // the end GC event.
1778
1779 print_hrm_post_compaction();
1780 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1781 }
1782
1783 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1784 if (hot_card_cache->use_cache()) {
1785 hot_card_cache->reset_card_counts();
1786 hot_card_cache->reset_hot_cache();
1787 }
1788
1789 // Rebuild remembered sets of all regions.
1790 uint n_workers =
1791 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1792 workers()->active_workers(),
1793 Threads::number_of_non_daemon_threads());
1794 workers()->set_active_workers(n_workers);
1795
1796 ParRebuildRSTask rebuild_rs_task(this);
1797 workers()->run_task(&rebuild_rs_task);
1798
1799 // Rebuild the strong code root lists for each region
1800 rebuild_strong_code_roots();
1801
1802 if (true) { // FIXME
1803 MetaspaceGC::compute_new_size();
1804 }
1805
1806 #ifdef TRACESPINNING
1807 ParallelTaskTerminator::print_termination_counts();
1808 #endif
1809
1810 // Discard all rset updates
1811 JavaThread::dirty_card_queue_set().abandon_logs();
1812 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1813
1814 _young_list->reset_sampled_info();
1815 // At this point there should be no regions in the
1816 // entire heap tagged as young.
1817 assert(check_young_list_empty(true /* check_heap */),
1818 "young list should be empty at this point");
1819
1820 // Update the number of full collections that have been completed.
1821 increment_old_marking_cycles_completed(false /* concurrent */);
1822
1823 _hrm.verify_optional();
1824 verify_region_sets_optional();
1825
1826 verify_after_gc();
1827
1828 // Clear the previous marking bitmap, if needed for bitmap verification.
1829 // Note we cannot do this when we clear the next marking bitmap in
1830 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1831 // objects marked during a full GC against the previous bitmap.
1832 // But we need to clear it before calling check_bitmaps below since
1833 // the full GC has compacted objects and updated TAMS but not updated
1834 // the prev bitmap.
1835 if (G1VerifyBitmaps) {
1836 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1837 }
1838 check_bitmaps("Full GC End");
1839
1840 // Start a new incremental collection set for the next pause
1841 assert(g1_policy()->collection_set() == NULL, "must be");
1842 g1_policy()->start_incremental_cset_building();
1843
1844 clear_cset_fast_test();
1845
1846 _allocator->init_mutator_alloc_region();
1847
1848 g1_policy()->record_full_collection_end();
1849
1850 if (G1Log::fine()) {
1851 g1_policy()->print_heap_transition();
1852 }
1853
1854 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1855 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1856 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1857 // before any GC notifications are raised.
1858 g1mm()->update_sizes();
1859
1860 gc_epilogue(true);
1861 }
1862
1863 if (G1Log::finer()) {
1864 g1_policy()->print_detailed_heap_transition(true /* full */);
1865 }
1866
1867 print_heap_after_gc();
1868 trace_heap_after_gc(gc_tracer);
1869
1870 post_full_gc_dump(gc_timer);
1871
1872 gc_timer->register_gc_end();
1873 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1874 }
1875
1876 return true;
1877 }
1878
1879 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1880 // do_collection() will return whether it succeeded in performing
1881 // the GC. Currently, there is no facility on the
1882 // do_full_collection() API to notify the caller than the collection
1883 // did not succeed (e.g., because it was locked out by the GC
1884 // locker). So, right now, we'll ignore the return value.
1885 bool dummy = do_collection(true, /* explicit_gc */
1886 clear_all_soft_refs,
1887 0 /* word_size */);
1888 }
1889
1890 // This code is mostly copied from TenuredGeneration.
1891 void
1892 G1CollectedHeap::
1893 resize_if_necessary_after_full_collection(size_t word_size) {
1894 // Include the current allocation, if any, and bytes that will be
1895 // pre-allocated to support collections, as "used".
1896 const size_t used_after_gc = used();
1897 const size_t capacity_after_gc = capacity();
1898 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1899
1900 // This is enforced in arguments.cpp.
1901 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1902 "otherwise the code below doesn't make sense");
1903
1904 // We don't have floating point command-line arguments
1905 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1906 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1907 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1908 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1909
1910 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1911 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1912
1913 // We have to be careful here as these two calculations can overflow
1914 // 32-bit size_t's.
1915 double used_after_gc_d = (double) used_after_gc;
1916 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1917 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1918
1919 // Let's make sure that they are both under the max heap size, which
1920 // by default will make them fit into a size_t.
1921 double desired_capacity_upper_bound = (double) max_heap_size;
1922 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1923 desired_capacity_upper_bound);
1924 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1925 desired_capacity_upper_bound);
1926
1927 // We can now safely turn them into size_t's.
1928 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1929 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1930
1931 // This assert only makes sense here, before we adjust them
1932 // with respect to the min and max heap size.
1933 assert(minimum_desired_capacity <= maximum_desired_capacity,
1934 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1935 "maximum_desired_capacity = " SIZE_FORMAT,
1936 minimum_desired_capacity, maximum_desired_capacity));
1937
1938 // Should not be greater than the heap max size. No need to adjust
1939 // it with respect to the heap min size as it's a lower bound (i.e.,
1940 // we'll try to make the capacity larger than it, not smaller).
1941 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1942 // Should not be less than the heap min size. No need to adjust it
1943 // with respect to the heap max size as it's an upper bound (i.e.,
1944 // we'll try to make the capacity smaller than it, not greater).
1945 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1946
1947 if (capacity_after_gc < minimum_desired_capacity) {
1948 // Don't expand unless it's significant
1949 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1950 ergo_verbose4(ErgoHeapSizing,
1951 "attempt heap expansion",
1952 ergo_format_reason("capacity lower than "
1953 "min desired capacity after Full GC")
1954 ergo_format_byte("capacity")
1955 ergo_format_byte("occupancy")
1956 ergo_format_byte_perc("min desired capacity"),
1957 capacity_after_gc, used_after_gc,
1958 minimum_desired_capacity, (double) MinHeapFreeRatio);
1959 expand(expand_bytes);
1960
1961 // No expansion, now see if we want to shrink
1962 } else if (capacity_after_gc > maximum_desired_capacity) {
1963 // Capacity too large, compute shrinking size
1964 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1965 ergo_verbose4(ErgoHeapSizing,
1966 "attempt heap shrinking",
1967 ergo_format_reason("capacity higher than "
1968 "max desired capacity after Full GC")
1969 ergo_format_byte("capacity")
1970 ergo_format_byte("occupancy")
1971 ergo_format_byte_perc("max desired capacity"),
1972 capacity_after_gc, used_after_gc,
1973 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1974 shrink(shrink_bytes);
1975 }
1976 }
1977
1978
1979 HeapWord*
1980 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1981 AllocationContext_t context,
1982 bool* succeeded) {
1983 assert_at_safepoint(true /* should_be_vm_thread */);
1984
1985 *succeeded = true;
1986 // Let's attempt the allocation first.
1987 HeapWord* result =
1988 attempt_allocation_at_safepoint(word_size,
1989 context,
1990 false /* expect_null_mutator_alloc_region */);
1991 if (result != NULL) {
1992 assert(*succeeded, "sanity");
1993 return result;
1994 }
1995
1996 // In a G1 heap, we're supposed to keep allocation from failing by
1997 // incremental pauses. Therefore, at least for now, we'll favor
1998 // expansion over collection. (This might change in the future if we can
1999 // do something smarter than full collection to satisfy a failed alloc.)
2000 result = expand_and_allocate(word_size, context);
2001 if (result != NULL) {
2002 assert(*succeeded, "sanity");
2003 return result;
2004 }
2005
2006 // Expansion didn't work, we'll try to do a Full GC.
2007 bool gc_succeeded = do_collection(false, /* explicit_gc */
2008 false, /* clear_all_soft_refs */
2009 word_size);
2010 if (!gc_succeeded) {
2011 *succeeded = false;
2012 return NULL;
2013 }
2014
2015 // Retry the allocation
2016 result = attempt_allocation_at_safepoint(word_size,
2017 context,
2018 true /* expect_null_mutator_alloc_region */);
2019 if (result != NULL) {
2020 assert(*succeeded, "sanity");
2021 return result;
2022 }
2023
2024 // Then, try a Full GC that will collect all soft references.
2025 gc_succeeded = do_collection(false, /* explicit_gc */
2026 true, /* clear_all_soft_refs */
2027 word_size);
2028 if (!gc_succeeded) {
2029 *succeeded = false;
2030 return NULL;
2031 }
2032
2033 // Retry the allocation once more
2034 result = attempt_allocation_at_safepoint(word_size,
2035 context,
2036 true /* expect_null_mutator_alloc_region */);
2037 if (result != NULL) {
2038 assert(*succeeded, "sanity");
2039 return result;
2040 }
2041
2042 assert(!collector_policy()->should_clear_all_soft_refs(),
2043 "Flag should have been handled and cleared prior to this point");
2044
2045 // What else? We might try synchronous finalization later. If the total
2046 // space available is large enough for the allocation, then a more
2047 // complete compaction phase than we've tried so far might be
2048 // appropriate.
2049 assert(*succeeded, "sanity");
2050 return NULL;
2051 }
2052
2053 // Attempting to expand the heap sufficiently
2054 // to support an allocation of the given "word_size". If
2055 // successful, perform the allocation and return the address of the
2056 // allocated block, or else "NULL".
2057
2058 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
2059 assert_at_safepoint(true /* should_be_vm_thread */);
2060
2061 verify_region_sets_optional();
2062
2063 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
2064 ergo_verbose1(ErgoHeapSizing,
2065 "attempt heap expansion",
2066 ergo_format_reason("allocation request failed")
2067 ergo_format_byte("allocation request"),
2068 word_size * HeapWordSize);
2069 if (expand(expand_bytes)) {
2070 _hrm.verify_optional();
2071 verify_region_sets_optional();
2072 return attempt_allocation_at_safepoint(word_size,
2073 context,
2074 false /* expect_null_mutator_alloc_region */);
2075 }
2076 return NULL;
2077 }
2078
2079 bool G1CollectedHeap::expand(size_t expand_bytes) {
2080 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
2081 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
2082 HeapRegion::GrainBytes);
2083 ergo_verbose2(ErgoHeapSizing,
2084 "expand the heap",
2085 ergo_format_byte("requested expansion amount")
2086 ergo_format_byte("attempted expansion amount"),
2087 expand_bytes, aligned_expand_bytes);
2088
2089 if (is_maximal_no_gc()) {
2090 ergo_verbose0(ErgoHeapSizing,
2091 "did not expand the heap",
2092 ergo_format_reason("heap already fully expanded"));
2093 return false;
2094 }
2095
2096 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
2097 assert(regions_to_expand > 0, "Must expand by at least one region");
2098
2099 uint expanded_by = _hrm.expand_by(regions_to_expand);
2100
2101 if (expanded_by > 0) {
2102 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
2103 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
2104 g1_policy()->record_new_heap_size(num_regions());
2105 } else {
2106 ergo_verbose0(ErgoHeapSizing,
2107 "did not expand the heap",
2108 ergo_format_reason("heap expansion operation failed"));
2109 // The expansion of the virtual storage space was unsuccessful.
2110 // Let's see if it was because we ran out of swap.
2111 if (G1ExitOnExpansionFailure &&
2112 _hrm.available() >= regions_to_expand) {
2113 // We had head room...
2114 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
2115 }
2116 }
2117 return regions_to_expand > 0;
2118 }
2119
2120 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
2121 size_t aligned_shrink_bytes =
2122 ReservedSpace::page_align_size_down(shrink_bytes);
2123 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
2124 HeapRegion::GrainBytes);
2125 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
2126
2127 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
2128 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
2129
2130 ergo_verbose3(ErgoHeapSizing,
2131 "shrink the heap",
2132 ergo_format_byte("requested shrinking amount")
2133 ergo_format_byte("aligned shrinking amount")
2134 ergo_format_byte("attempted shrinking amount"),
2135 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
2136 if (num_regions_removed > 0) {
2137 g1_policy()->record_new_heap_size(num_regions());
2138 } else {
2139 ergo_verbose0(ErgoHeapSizing,
2140 "did not shrink the heap",
2141 ergo_format_reason("heap shrinking operation failed"));
2142 }
2143 }
2144
2145 void G1CollectedHeap::shrink(size_t shrink_bytes) {
2146 verify_region_sets_optional();
2147
2148 // We should only reach here at the end of a Full GC which means we
2149 // should not not be holding to any GC alloc regions. The method
2150 // below will make sure of that and do any remaining clean up.
2151 _allocator->abandon_gc_alloc_regions();
2152
2153 // Instead of tearing down / rebuilding the free lists here, we
2154 // could instead use the remove_all_pending() method on free_list to
2155 // remove only the ones that we need to remove.
2156 tear_down_region_sets(true /* free_list_only */);
2157 shrink_helper(shrink_bytes);
2158 rebuild_region_sets(true /* free_list_only */);
2159
2160 _hrm.verify_optional();
2161 verify_region_sets_optional();
2162 }
2163
2164 // Public methods.
2165
2166 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
2167 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
2168 #endif // _MSC_VER
2169
2170
2171 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2172 CollectedHeap(),
2173 _g1_policy(policy_),
2174 _dirty_card_queue_set(false),
2175 _into_cset_dirty_card_queue_set(false),
2176 _is_alive_closure_cm(this),
2177 _is_alive_closure_stw(this),
2178 _ref_processor_cm(NULL),
2179 _ref_processor_stw(NULL),
2180 _bot_shared(NULL),
2181 _cg1r(NULL),
2182 _g1mm(NULL),
2183 _refine_cte_cl_concurrency(true),
2184 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2185 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2186 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2187 _humongous_reclaim_candidates(),
2188 _has_humongous_reclaim_candidates(false),
2189 _archive_allocator(NULL),
2190 _free_regions_coming(false),
2191 _young_list(new YoungList(this)),
2192 _gc_time_stamp(0),
2193 _summary_bytes_used(0),
2194 _survivor_plab_stats(YoungPLABSize, PLABWeight),
2195 _old_plab_stats(OldPLABSize, PLABWeight),
2196 _expand_heap_after_alloc_failure(true),
2197 _surviving_young_words(NULL),
2198 _old_marking_cycles_started(0),
2199 _old_marking_cycles_completed(0),
2200 _heap_summary_sent(false),
2201 _in_cset_fast_test(),
2202 _dirty_cards_region_list(NULL),
2203 _worker_cset_start_region(NULL),
2204 _worker_cset_start_region_time_stamp(NULL),
2205 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2206 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2207 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2208 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2209
2210 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
2211 /* are_GC_task_threads */true,
2212 /* are_ConcurrentGC_threads */false);
2213 _workers->initialize_workers();
2214
2215 _allocator = G1Allocator::create_allocator(this);
2216 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2217
2218 // Override the default _filler_array_max_size so that no humongous filler
2219 // objects are created.
2220 _filler_array_max_size = _humongous_object_threshold_in_words;
2221
2222 uint n_queues = ParallelGCThreads;
2223 _task_queues = new RefToScanQueueSet(n_queues);
2224
2225 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2226 assert(n_rem_sets > 0, "Invariant.");
2227
2228 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2229 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2230 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2231
2232 for (uint i = 0; i < n_queues; i++) {
2233 RefToScanQueue* q = new RefToScanQueue();
2234 q->initialize();
2235 _task_queues->register_queue(i, q);
2236 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2237 }
2238 clear_cset_start_regions();
2239
2240 // Initialize the G1EvacuationFailureALot counters and flags.
2241 NOT_PRODUCT(reset_evacuation_should_fail();)
2242
2243 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2244 }
2245
2246 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2247 size_t size,
2248 size_t translation_factor) {
2249 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2250 // Allocate a new reserved space, preferring to use large pages.
2251 ReservedSpace rs(size, preferred_page_size);
2252 G1RegionToSpaceMapper* result =
2253 G1RegionToSpaceMapper::create_mapper(rs,
2254 size,
2255 rs.alignment(),
2256 HeapRegion::GrainBytes,
2257 translation_factor,
2258 mtGC);
2259 if (TracePageSizes) {
2260 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2261 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2262 }
2263 return result;
2264 }
2265
2266 jint G1CollectedHeap::initialize() {
2267 CollectedHeap::pre_initialize();
2268 os::enable_vtime();
2269
2270 G1Log::init();
2271
2272 // Necessary to satisfy locking discipline assertions.
2273
2274 MutexLocker x(Heap_lock);
2275
2276 // We have to initialize the printer before committing the heap, as
2277 // it will be used then.
2278 _hr_printer.set_active(G1PrintHeapRegions);
2279
2280 // While there are no constraints in the GC code that HeapWordSize
2281 // be any particular value, there are multiple other areas in the
2282 // system which believe this to be true (e.g. oop->object_size in some
2283 // cases incorrectly returns the size in wordSize units rather than
2284 // HeapWordSize).
2285 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2286
2287 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2288 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2289 size_t heap_alignment = collector_policy()->heap_alignment();
2290
2291 // Ensure that the sizes are properly aligned.
2292 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2293 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2294 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2295
2296 _cg1r = new ConcurrentG1Refine(this);
2297
2298 // Reserve the maximum.
2299
2300 // When compressed oops are enabled, the preferred heap base
2301 // is calculated by subtracting the requested size from the
2302 // 32Gb boundary and using the result as the base address for
2303 // heap reservation. If the requested size is not aligned to
2304 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2305 // into the ReservedHeapSpace constructor) then the actual
2306 // base of the reserved heap may end up differing from the
2307 // address that was requested (i.e. the preferred heap base).
2308 // If this happens then we could end up using a non-optimal
2309 // compressed oops mode.
2310
2311 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2312 heap_alignment);
2313
2314 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2315
2316 // Create the barrier set for the entire reserved region.
2317 G1SATBCardTableLoggingModRefBS* bs
2318 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2319 bs->initialize();
2320 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2321 set_barrier_set(bs);
2322
2323 // Also create a G1 rem set.
2324 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2325
2326 // Carve out the G1 part of the heap.
2327
2328 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2329 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2330 G1RegionToSpaceMapper* heap_storage =
2331 G1RegionToSpaceMapper::create_mapper(g1_rs,
2332 g1_rs.size(),
2333 page_size,
2334 HeapRegion::GrainBytes,
2335 1,
2336 mtJavaHeap);
2337 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2338 max_byte_size, page_size,
2339 heap_rs.base(),
2340 heap_rs.size());
2341 heap_storage->set_mapping_changed_listener(&_listener);
2342
2343 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2344 G1RegionToSpaceMapper* bot_storage =
2345 create_aux_memory_mapper("Block offset table",
2346 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2347 G1BlockOffsetSharedArray::heap_map_factor());
2348
2349 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2350 G1RegionToSpaceMapper* cardtable_storage =
2351 create_aux_memory_mapper("Card table",
2352 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2353 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2354
2355 G1RegionToSpaceMapper* card_counts_storage =
2356 create_aux_memory_mapper("Card counts table",
2357 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2358 G1CardCounts::heap_map_factor());
2359
2360 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2361 G1RegionToSpaceMapper* prev_bitmap_storage =
2362 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2363 G1RegionToSpaceMapper* next_bitmap_storage =
2364 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2365
2366 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2367 g1_barrier_set()->initialize(cardtable_storage);
2368 // Do later initialization work for concurrent refinement.
2369 _cg1r->init(card_counts_storage);
2370
2371 // 6843694 - ensure that the maximum region index can fit
2372 // in the remembered set structures.
2373 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2374 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2375
2376 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2377 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2378 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2379 "too many cards per region");
2380
2381 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2382
2383 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2384
2385 {
2386 HeapWord* start = _hrm.reserved().start();
2387 HeapWord* end = _hrm.reserved().end();
2388 size_t granularity = HeapRegion::GrainBytes;
2389
2390 _in_cset_fast_test.initialize(start, end, granularity);
2391 _humongous_reclaim_candidates.initialize(start, end, granularity);
2392 }
2393
2394 // Create the ConcurrentMark data structure and thread.
2395 // (Must do this late, so that "max_regions" is defined.)
2396 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2397 if (_cm == NULL || !_cm->completed_initialization()) {
2398 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2399 return JNI_ENOMEM;
2400 }
2401 _cmThread = _cm->cmThread();
2402
2403 // Initialize the from_card cache structure of HeapRegionRemSet.
2404 HeapRegionRemSet::init_heap(max_regions());
2405
2406 // Now expand into the initial heap size.
2407 if (!expand(init_byte_size)) {
2408 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2409 return JNI_ENOMEM;
2410 }
2411
2412 // Perform any initialization actions delegated to the policy.
2413 g1_policy()->init();
2414
2415 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2416 SATB_Q_FL_lock,
2417 G1SATBProcessCompletedThreshold,
2418 Shared_SATB_Q_lock);
2419
2420 JavaThread::dirty_card_queue_set().initialize(true,
2421 DirtyCardQ_CBL_mon,
2422 DirtyCardQ_FL_lock,
2423 concurrent_g1_refine()->yellow_zone(),
2424 concurrent_g1_refine()->red_zone(),
2425 Shared_DirtyCardQ_lock);
2426
2427 dirty_card_queue_set().initialize(false, // Should never be called by the Java code
2428 DirtyCardQ_CBL_mon,
2429 DirtyCardQ_FL_lock,
2430 -1, // never trigger processing
2431 -1, // no limit on length
2432 Shared_DirtyCardQ_lock,
2433 &JavaThread::dirty_card_queue_set());
2434
2435 // Initialize the card queue set used to hold cards containing
2436 // references into the collection set.
2437 _into_cset_dirty_card_queue_set.initialize(false, // Should never be called by the Java code
2438 DirtyCardQ_CBL_mon,
2439 DirtyCardQ_FL_lock,
2440 -1, // never trigger processing
2441 -1, // no limit on length
2442 Shared_DirtyCardQ_lock,
2443 &JavaThread::dirty_card_queue_set());
2444
2445 // Here we allocate the dummy HeapRegion that is required by the
2446 // G1AllocRegion class.
2447 HeapRegion* dummy_region = _hrm.get_dummy_region();
2448
2449 // We'll re-use the same region whether the alloc region will
2450 // require BOT updates or not and, if it doesn't, then a non-young
2451 // region will complain that it cannot support allocations without
2452 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2453 dummy_region->set_eden();
2454 // Make sure it's full.
2455 dummy_region->set_top(dummy_region->end());
2456 G1AllocRegion::setup(this, dummy_region);
2457
2458 _allocator->init_mutator_alloc_region();
2459
2460 // Do create of the monitoring and management support so that
2461 // values in the heap have been properly initialized.
2462 _g1mm = new G1MonitoringSupport(this);
2463
2464 G1StringDedup::initialize();
2465
2466 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2467 for (uint i = 0; i < ParallelGCThreads; i++) {
2468 new (&_preserved_objs[i]) OopAndMarkOopStack();
2469 }
2470
2471 return JNI_OK;
2472 }
2473
2474 void G1CollectedHeap::stop() {
2475 // Stop all concurrent threads. We do this to make sure these threads
2476 // do not continue to execute and access resources (e.g. gclog_or_tty)
2477 // that are destroyed during shutdown.
2478 _cg1r->stop();
2479 _cmThread->stop();
2480 if (G1StringDedup::is_enabled()) {
2481 G1StringDedup::stop();
2482 }
2483 }
2484
2485 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2486 return HeapRegion::max_region_size();
2487 }
2488
2489 void G1CollectedHeap::post_initialize() {
2490 CollectedHeap::post_initialize();
2491 ref_processing_init();
2492 }
2493
2494 void G1CollectedHeap::ref_processing_init() {
2495 // Reference processing in G1 currently works as follows:
2496 //
2497 // * There are two reference processor instances. One is
2498 // used to record and process discovered references
2499 // during concurrent marking; the other is used to
2500 // record and process references during STW pauses
2501 // (both full and incremental).
2502 // * Both ref processors need to 'span' the entire heap as
2503 // the regions in the collection set may be dotted around.
2504 //
2505 // * For the concurrent marking ref processor:
2506 // * Reference discovery is enabled at initial marking.
2507 // * Reference discovery is disabled and the discovered
2508 // references processed etc during remarking.
2509 // * Reference discovery is MT (see below).
2510 // * Reference discovery requires a barrier (see below).
2511 // * Reference processing may or may not be MT
2512 // (depending on the value of ParallelRefProcEnabled
2513 // and ParallelGCThreads).
2514 // * A full GC disables reference discovery by the CM
2515 // ref processor and abandons any entries on it's
2516 // discovered lists.
2517 //
2518 // * For the STW processor:
2519 // * Non MT discovery is enabled at the start of a full GC.
2520 // * Processing and enqueueing during a full GC is non-MT.
2521 // * During a full GC, references are processed after marking.
2522 //
2523 // * Discovery (may or may not be MT) is enabled at the start
2524 // of an incremental evacuation pause.
2525 // * References are processed near the end of a STW evacuation pause.
2526 // * For both types of GC:
2527 // * Discovery is atomic - i.e. not concurrent.
2528 // * Reference discovery will not need a barrier.
2529
2530 MemRegion mr = reserved_region();
2531
2532 // Concurrent Mark ref processor
2533 _ref_processor_cm =
2534 new ReferenceProcessor(mr, // span
2535 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2536 // mt processing
2537 ParallelGCThreads,
2538 // degree of mt processing
2539 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2540 // mt discovery
2541 MAX2(ParallelGCThreads, ConcGCThreads),
2542 // degree of mt discovery
2543 false,
2544 // Reference discovery is not atomic
2545 &_is_alive_closure_cm);
2546 // is alive closure
2547 // (for efficiency/performance)
2548
2549 // STW ref processor
2550 _ref_processor_stw =
2551 new ReferenceProcessor(mr, // span
2552 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2553 // mt processing
2554 ParallelGCThreads,
2555 // degree of mt processing
2556 (ParallelGCThreads > 1),
2557 // mt discovery
2558 ParallelGCThreads,
2559 // degree of mt discovery
2560 true,
2561 // Reference discovery is atomic
2562 &_is_alive_closure_stw);
2563 // is alive closure
2564 // (for efficiency/performance)
2565 }
2566
2567 size_t G1CollectedHeap::capacity() const {
2568 return _hrm.length() * HeapRegion::GrainBytes;
2569 }
2570
2571 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2572 assert(!hr->is_continues_humongous(), "pre-condition");
2573 hr->reset_gc_time_stamp();
2574 if (hr->is_starts_humongous()) {
2575 uint first_index = hr->hrm_index() + 1;
2576 uint last_index = hr->last_hc_index();
2577 for (uint i = first_index; i < last_index; i += 1) {
2578 HeapRegion* chr = region_at(i);
2579 assert(chr->is_continues_humongous(), "sanity");
2580 chr->reset_gc_time_stamp();
2581 }
2582 }
2583 }
2584
2585 #ifndef PRODUCT
2586
2587 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2588 private:
2589 unsigned _gc_time_stamp;
2590 bool _failures;
2591
2592 public:
2593 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2594 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2595
2596 virtual bool doHeapRegion(HeapRegion* hr) {
2597 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2598 if (_gc_time_stamp != region_gc_time_stamp) {
2599 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2600 "expected %d", HR_FORMAT_PARAMS(hr),
2601 region_gc_time_stamp, _gc_time_stamp);
2602 _failures = true;
2603 }
2604 return false;
2605 }
2606
2607 bool failures() { return _failures; }
2608 };
2609
2610 void G1CollectedHeap::check_gc_time_stamps() {
2611 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2612 heap_region_iterate(&cl);
2613 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2614 }
2615 #endif // PRODUCT
2616
2617 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2618 DirtyCardQueue* into_cset_dcq,
2619 bool concurrent,
2620 uint worker_i) {
2621 // Clean cards in the hot card cache
2622 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2623 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2624
2625 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2626 size_t n_completed_buffers = 0;
2627 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2628 n_completed_buffers++;
2629 }
2630 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2631 dcqs.clear_n_completed_buffers();
2632 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2633 }
2634
2635
2636 // Computes the sum of the storage used by the various regions.
2637 size_t G1CollectedHeap::used() const {
2638 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2639 if (_archive_allocator != NULL) {
2640 result += _archive_allocator->used();
2641 }
2642 return result;
2643 }
2644
2645 size_t G1CollectedHeap::used_unlocked() const {
2646 return _summary_bytes_used;
2647 }
2648
2649 class SumUsedClosure: public HeapRegionClosure {
2650 size_t _used;
2651 public:
2652 SumUsedClosure() : _used(0) {}
2653 bool doHeapRegion(HeapRegion* r) {
2654 if (!r->is_continues_humongous()) {
2655 _used += r->used();
2656 }
2657 return false;
2658 }
2659 size_t result() { return _used; }
2660 };
2661
2662 size_t G1CollectedHeap::recalculate_used() const {
2663 double recalculate_used_start = os::elapsedTime();
2664
2665 SumUsedClosure blk;
2666 heap_region_iterate(&blk);
2667
2668 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2669 return blk.result();
2670 }
2671
2672 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2673 switch (cause) {
2674 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2675 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2676 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2677 case GCCause::_g1_humongous_allocation: return true;
2678 case GCCause::_update_allocation_context_stats_inc: return true;
2679 case GCCause::_wb_conc_mark: return true;
2680 default: return false;
2681 }
2682 }
2683
2684 #ifndef PRODUCT
2685 void G1CollectedHeap::allocate_dummy_regions() {
2686 // Let's fill up most of the region
2687 size_t word_size = HeapRegion::GrainWords - 1024;
2688 // And as a result the region we'll allocate will be humongous.
2689 guarantee(is_humongous(word_size), "sanity");
2690
2691 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2692 // Let's use the existing mechanism for the allocation
2693 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2694 AllocationContext::system());
2695 if (dummy_obj != NULL) {
2696 MemRegion mr(dummy_obj, word_size);
2697 CollectedHeap::fill_with_object(mr);
2698 } else {
2699 // If we can't allocate once, we probably cannot allocate
2700 // again. Let's get out of the loop.
2701 break;
2702 }
2703 }
2704 }
2705 #endif // !PRODUCT
2706
2707 void G1CollectedHeap::increment_old_marking_cycles_started() {
2708 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2709 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2710 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2711 _old_marking_cycles_started, _old_marking_cycles_completed));
2712
2713 _old_marking_cycles_started++;
2714 }
2715
2716 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2717 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2718
2719 // We assume that if concurrent == true, then the caller is a
2720 // concurrent thread that was joined the Suspendible Thread
2721 // Set. If there's ever a cheap way to check this, we should add an
2722 // assert here.
2723
2724 // Given that this method is called at the end of a Full GC or of a
2725 // concurrent cycle, and those can be nested (i.e., a Full GC can
2726 // interrupt a concurrent cycle), the number of full collections
2727 // completed should be either one (in the case where there was no
2728 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2729 // behind the number of full collections started.
2730
2731 // This is the case for the inner caller, i.e. a Full GC.
2732 assert(concurrent ||
2733 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2734 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2735 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2736 "is inconsistent with _old_marking_cycles_completed = %u",
2737 _old_marking_cycles_started, _old_marking_cycles_completed));
2738
2739 // This is the case for the outer caller, i.e. the concurrent cycle.
2740 assert(!concurrent ||
2741 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2742 err_msg("for outer caller (concurrent cycle): "
2743 "_old_marking_cycles_started = %u "
2744 "is inconsistent with _old_marking_cycles_completed = %u",
2745 _old_marking_cycles_started, _old_marking_cycles_completed));
2746
2747 _old_marking_cycles_completed += 1;
2748
2749 // We need to clear the "in_progress" flag in the CM thread before
2750 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2751 // is set) so that if a waiter requests another System.gc() it doesn't
2752 // incorrectly see that a marking cycle is still in progress.
2753 if (concurrent) {
2754 _cmThread->set_idle();
2755 }
2756
2757 // This notify_all() will ensure that a thread that called
2758 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2759 // and it's waiting for a full GC to finish will be woken up. It is
2760 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2761 FullGCCount_lock->notify_all();
2762 }
2763
2764 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2765 collector_state()->set_concurrent_cycle_started(true);
2766 _gc_timer_cm->register_gc_start(start_time);
2767
2768 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2769 trace_heap_before_gc(_gc_tracer_cm);
2770 }
2771
2772 void G1CollectedHeap::register_concurrent_cycle_end() {
2773 if (collector_state()->concurrent_cycle_started()) {
2774 if (_cm->has_aborted()) {
2775 _gc_tracer_cm->report_concurrent_mode_failure();
2776 }
2777
2778 _gc_timer_cm->register_gc_end();
2779 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2780
2781 // Clear state variables to prepare for the next concurrent cycle.
2782 collector_state()->set_concurrent_cycle_started(false);
2783 _heap_summary_sent = false;
2784 }
2785 }
2786
2787 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2788 if (collector_state()->concurrent_cycle_started()) {
2789 // This function can be called when:
2790 // the cleanup pause is run
2791 // the concurrent cycle is aborted before the cleanup pause.
2792 // the concurrent cycle is aborted after the cleanup pause,
2793 // but before the concurrent cycle end has been registered.
2794 // Make sure that we only send the heap information once.
2795 if (!_heap_summary_sent) {
2796 trace_heap_after_gc(_gc_tracer_cm);
2797 _heap_summary_sent = true;
2798 }
2799 }
2800 }
2801
2802 void G1CollectedHeap::collect(GCCause::Cause cause) {
2803 assert_heap_not_locked();
2804
2805 uint gc_count_before;
2806 uint old_marking_count_before;
2807 uint full_gc_count_before;
2808 bool retry_gc;
2809
2810 do {
2811 retry_gc = false;
2812
2813 {
2814 MutexLocker ml(Heap_lock);
2815
2816 // Read the GC count while holding the Heap_lock
2817 gc_count_before = total_collections();
2818 full_gc_count_before = total_full_collections();
2819 old_marking_count_before = _old_marking_cycles_started;
2820 }
2821
2822 if (should_do_concurrent_full_gc(cause)) {
2823 // Schedule an initial-mark evacuation pause that will start a
2824 // concurrent cycle. We're setting word_size to 0 which means that
2825 // we are not requesting a post-GC allocation.
2826 VM_G1IncCollectionPause op(gc_count_before,
2827 0, /* word_size */
2828 true, /* should_initiate_conc_mark */
2829 g1_policy()->max_pause_time_ms(),
2830 cause);
2831 op.set_allocation_context(AllocationContext::current());
2832
2833 VMThread::execute(&op);
2834 if (!op.pause_succeeded()) {
2835 if (old_marking_count_before == _old_marking_cycles_started) {
2836 retry_gc = op.should_retry_gc();
2837 } else {
2838 // A Full GC happened while we were trying to schedule the
2839 // initial-mark GC. No point in starting a new cycle given
2840 // that the whole heap was collected anyway.
2841 }
2842
2843 if (retry_gc) {
2844 if (GC_locker::is_active_and_needs_gc()) {
2845 GC_locker::stall_until_clear();
2846 }
2847 }
2848 }
2849 } else {
2850 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2851 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2852
2853 // Schedule a standard evacuation pause. We're setting word_size
2854 // to 0 which means that we are not requesting a post-GC allocation.
2855 VM_G1IncCollectionPause op(gc_count_before,
2856 0, /* word_size */
2857 false, /* should_initiate_conc_mark */
2858 g1_policy()->max_pause_time_ms(),
2859 cause);
2860 VMThread::execute(&op);
2861 } else {
2862 // Schedule a Full GC.
2863 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2864 VMThread::execute(&op);
2865 }
2866 }
2867 } while (retry_gc);
2868 }
2869
2870 bool G1CollectedHeap::is_in(const void* p) const {
2871 if (_hrm.reserved().contains(p)) {
2872 // Given that we know that p is in the reserved space,
2873 // heap_region_containing_raw() should successfully
2874 // return the containing region.
2875 HeapRegion* hr = heap_region_containing_raw(p);
2876 return hr->is_in(p);
2877 } else {
2878 return false;
2879 }
2880 }
2881
2882 #ifdef ASSERT
2883 bool G1CollectedHeap::is_in_exact(const void* p) const {
2884 bool contains = reserved_region().contains(p);
2885 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2886 if (contains && available) {
2887 return true;
2888 } else {
2889 return false;
2890 }
2891 }
2892 #endif
2893
2894 // Iteration functions.
2895
2896 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2897
2898 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2899 ExtendedOopClosure* _cl;
2900 public:
2901 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2902 bool doHeapRegion(HeapRegion* r) {
2903 if (!r->is_continues_humongous()) {
2904 r->oop_iterate(_cl);
2905 }
2906 return false;
2907 }
2908 };
2909
2910 // Iterates an ObjectClosure over all objects within a HeapRegion.
2911
2912 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2913 ObjectClosure* _cl;
2914 public:
2915 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2916 bool doHeapRegion(HeapRegion* r) {
2917 if (!r->is_continues_humongous()) {
2918 r->object_iterate(_cl);
2919 }
2920 return false;
2921 }
2922 };
2923
2924 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2925 IterateObjectClosureRegionClosure blk(cl);
2926 heap_region_iterate(&blk);
2927 }
2928
2929 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2930 _hrm.iterate(cl);
2931 }
2932
2933 void
2934 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2935 uint worker_id,
2936 HeapRegionClaimer *hrclaimer,
2937 bool concurrent) const {
2938 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2939 }
2940
2941 // Clear the cached CSet starting regions and (more importantly)
2942 // the time stamps. Called when we reset the GC time stamp.
2943 void G1CollectedHeap::clear_cset_start_regions() {
2944 assert(_worker_cset_start_region != NULL, "sanity");
2945 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2946
2947 for (uint i = 0; i < ParallelGCThreads; i++) {
2948 _worker_cset_start_region[i] = NULL;
2949 _worker_cset_start_region_time_stamp[i] = 0;
2950 }
2951 }
2952
2953 // Given the id of a worker, obtain or calculate a suitable
2954 // starting region for iterating over the current collection set.
2955 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2956 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2957
2958 HeapRegion* result = NULL;
2959 unsigned gc_time_stamp = get_gc_time_stamp();
2960
2961 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2962 // Cached starting region for current worker was set
2963 // during the current pause - so it's valid.
2964 // Note: the cached starting heap region may be NULL
2965 // (when the collection set is empty).
2966 result = _worker_cset_start_region[worker_i];
2967 assert(result == NULL || result->in_collection_set(), "sanity");
2968 return result;
2969 }
2970
2971 // The cached entry was not valid so let's calculate
2972 // a suitable starting heap region for this worker.
2973
2974 // We want the parallel threads to start their collection
2975 // set iteration at different collection set regions to
2976 // avoid contention.
2977 // If we have:
2978 // n collection set regions
2979 // p threads
2980 // Then thread t will start at region floor ((t * n) / p)
2981
2982 result = g1_policy()->collection_set();
2983 uint cs_size = g1_policy()->cset_region_length();
2984 uint active_workers = workers()->active_workers();
2985
2986 uint end_ind = (cs_size * worker_i) / active_workers;
2987 uint start_ind = 0;
2988
2989 if (worker_i > 0 &&
2990 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2991 // Previous workers starting region is valid
2992 // so let's iterate from there
2993 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2994 result = _worker_cset_start_region[worker_i - 1];
2995 }
2996
2997 for (uint i = start_ind; i < end_ind; i++) {
2998 result = result->next_in_collection_set();
2999 }
3000
3001 // Note: the calculated starting heap region may be NULL
3002 // (when the collection set is empty).
3003 assert(result == NULL || result->in_collection_set(), "sanity");
3004 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
3005 "should be updated only once per pause");
3006 _worker_cset_start_region[worker_i] = result;
3007 OrderAccess::storestore();
3008 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
3009 return result;
3010 }
3011
3012 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
3013 HeapRegion* r = g1_policy()->collection_set();
3014 while (r != NULL) {
3015 HeapRegion* next = r->next_in_collection_set();
3016 if (cl->doHeapRegion(r)) {
3017 cl->incomplete();
3018 return;
3019 }
3020 r = next;
3021 }
3022 }
3023
3024 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
3025 HeapRegionClosure *cl) {
3026 if (r == NULL) {
3027 // The CSet is empty so there's nothing to do.
3028 return;
3029 }
3030
3031 assert(r->in_collection_set(),
3032 "Start region must be a member of the collection set.");
3033 HeapRegion* cur = r;
3034 while (cur != NULL) {
3035 HeapRegion* next = cur->next_in_collection_set();
3036 if (cl->doHeapRegion(cur) && false) {
3037 cl->incomplete();
3038 return;
3039 }
3040 cur = next;
3041 }
3042 cur = g1_policy()->collection_set();
3043 while (cur != r) {
3044 HeapRegion* next = cur->next_in_collection_set();
3045 if (cl->doHeapRegion(cur) && false) {
3046 cl->incomplete();
3047 return;
3048 }
3049 cur = next;
3050 }
3051 }
3052
3053 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
3054 HeapRegion* result = _hrm.next_region_in_heap(from);
3055 while (result != NULL && result->is_pinned()) {
3056 result = _hrm.next_region_in_heap(result);
3057 }
3058 return result;
3059 }
3060
3061 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3062 HeapRegion* hr = heap_region_containing(addr);
3063 return hr->block_start(addr);
3064 }
3065
3066 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3067 HeapRegion* hr = heap_region_containing(addr);
3068 return hr->block_size(addr);
3069 }
3070
3071 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3072 HeapRegion* hr = heap_region_containing(addr);
3073 return hr->block_is_obj(addr);
3074 }
3075
3076 bool G1CollectedHeap::supports_tlab_allocation() const {
3077 return true;
3078 }
3079
3080 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3081 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3082 }
3083
3084 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3085 return young_list()->eden_used_bytes();
3086 }
3087
3088 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3089 // must be smaller than the humongous object limit.
3090 size_t G1CollectedHeap::max_tlab_size() const {
3091 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3092 }
3093
3094 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3095 // Return the remaining space in the cur alloc region, but not less than
3096 // the min TLAB size.
3097
3098 // Also, this value can be at most the humongous object threshold,
3099 // since we can't allow tlabs to grow big enough to accommodate
3100 // humongous objects.
3101
3102 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
3103 size_t max_tlab = max_tlab_size() * wordSize;
3104 if (hr == NULL) {
3105 return max_tlab;
3106 } else {
3107 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3108 }
3109 }
3110
3111 size_t G1CollectedHeap::max_capacity() const {
3112 return _hrm.reserved().byte_size();
3113 }
3114
3115 jlong G1CollectedHeap::millis_since_last_gc() {
3116 // assert(false, "NYI");
3117 return 0;
3118 }
3119
3120 void G1CollectedHeap::prepare_for_verify() {
3121 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3122 ensure_parsability(false);
3123 }
3124 g1_rem_set()->prepare_for_verify();
3125 }
3126
3127 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3128 VerifyOption vo) {
3129 switch (vo) {
3130 case VerifyOption_G1UsePrevMarking:
3131 return hr->obj_allocated_since_prev_marking(obj);
3132 case VerifyOption_G1UseNextMarking:
3133 return hr->obj_allocated_since_next_marking(obj);
3134 case VerifyOption_G1UseMarkWord:
3135 return false;
3136 default:
3137 ShouldNotReachHere();
3138 }
3139 return false; // keep some compilers happy
3140 }
3141
3142 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3143 switch (vo) {
3144 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3145 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3146 case VerifyOption_G1UseMarkWord: return NULL;
3147 default: ShouldNotReachHere();
3148 }
3149 return NULL; // keep some compilers happy
3150 }
3151
3152 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3153 switch (vo) {
3154 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3155 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3156 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3157 default: ShouldNotReachHere();
3158 }
3159 return false; // keep some compilers happy
3160 }
3161
3162 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3163 switch (vo) {
3164 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3165 case VerifyOption_G1UseNextMarking: return "NTAMS";
3166 case VerifyOption_G1UseMarkWord: return "NONE";
3167 default: ShouldNotReachHere();
3168 }
3169 return NULL; // keep some compilers happy
3170 }
3171
3172 class VerifyRootsClosure: public OopClosure {
3173 private:
3174 G1CollectedHeap* _g1h;
3175 VerifyOption _vo;
3176 bool _failures;
3177 public:
3178 // _vo == UsePrevMarking -> use "prev" marking information,
3179 // _vo == UseNextMarking -> use "next" marking information,
3180 // _vo == UseMarkWord -> use mark word from object header.
3181 VerifyRootsClosure(VerifyOption vo) :
3182 _g1h(G1CollectedHeap::heap()),
3183 _vo(vo),
3184 _failures(false) { }
3185
3186 bool failures() { return _failures; }
3187
3188 template <class T> void do_oop_nv(T* p) {
3189 T heap_oop = oopDesc::load_heap_oop(p);
3190 if (!oopDesc::is_null(heap_oop)) {
3191 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3192 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3193 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3194 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3195 if (_vo == VerifyOption_G1UseMarkWord) {
3196 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3197 }
3198 obj->print_on(gclog_or_tty);
3199 _failures = true;
3200 }
3201 }
3202 }
3203
3204 void do_oop(oop* p) { do_oop_nv(p); }
3205 void do_oop(narrowOop* p) { do_oop_nv(p); }
3206 };
3207
3208 class G1VerifyCodeRootOopClosure: public OopClosure {
3209 G1CollectedHeap* _g1h;
3210 OopClosure* _root_cl;
3211 nmethod* _nm;
3212 VerifyOption _vo;
3213 bool _failures;
3214
3215 template <class T> void do_oop_work(T* p) {
3216 // First verify that this root is live
3217 _root_cl->do_oop(p);
3218
3219 if (!G1VerifyHeapRegionCodeRoots) {
3220 // We're not verifying the code roots attached to heap region.
3221 return;
3222 }
3223
3224 // Don't check the code roots during marking verification in a full GC
3225 if (_vo == VerifyOption_G1UseMarkWord) {
3226 return;
3227 }
3228
3229 // Now verify that the current nmethod (which contains p) is
3230 // in the code root list of the heap region containing the
3231 // object referenced by p.
3232
3233 T heap_oop = oopDesc::load_heap_oop(p);
3234 if (!oopDesc::is_null(heap_oop)) {
3235 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3236
3237 // Now fetch the region containing the object
3238 HeapRegion* hr = _g1h->heap_region_containing(obj);
3239 HeapRegionRemSet* hrrs = hr->rem_set();
3240 // Verify that the strong code root list for this region
3241 // contains the nmethod
3242 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3243 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3244 "from nmethod " PTR_FORMAT " not in strong "
3245 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3246 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3247 _failures = true;
3248 }
3249 }
3250 }
3251
3252 public:
3253 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3254 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3255
3256 void do_oop(oop* p) { do_oop_work(p); }
3257 void do_oop(narrowOop* p) { do_oop_work(p); }
3258
3259 void set_nmethod(nmethod* nm) { _nm = nm; }
3260 bool failures() { return _failures; }
3261 };
3262
3263 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3264 G1VerifyCodeRootOopClosure* _oop_cl;
3265
3266 public:
3267 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3268 _oop_cl(oop_cl) {}
3269
3270 void do_code_blob(CodeBlob* cb) {
3271 nmethod* nm = cb->as_nmethod_or_null();
3272 if (nm != NULL) {
3273 _oop_cl->set_nmethod(nm);
3274 nm->oops_do(_oop_cl);
3275 }
3276 }
3277 };
3278
3279 class YoungRefCounterClosure : public OopClosure {
3280 G1CollectedHeap* _g1h;
3281 int _count;
3282 public:
3283 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3284 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3285 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3286
3287 int count() { return _count; }
3288 void reset_count() { _count = 0; };
3289 };
3290
3291 class VerifyKlassClosure: public KlassClosure {
3292 YoungRefCounterClosure _young_ref_counter_closure;
3293 OopClosure *_oop_closure;
3294 public:
3295 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3296 void do_klass(Klass* k) {
3297 k->oops_do(_oop_closure);
3298
3299 _young_ref_counter_closure.reset_count();
3300 k->oops_do(&_young_ref_counter_closure);
3301 if (_young_ref_counter_closure.count() > 0) {
3302 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3303 }
3304 }
3305 };
3306
3307 class VerifyLivenessOopClosure: public OopClosure {
3308 G1CollectedHeap* _g1h;
3309 VerifyOption _vo;
3310 public:
3311 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3312 _g1h(g1h), _vo(vo)
3313 { }
3314 void do_oop(narrowOop *p) { do_oop_work(p); }
3315 void do_oop( oop *p) { do_oop_work(p); }
3316
3317 template <class T> void do_oop_work(T *p) {
3318 oop obj = oopDesc::load_decode_heap_oop(p);
3319 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3320 "Dead object referenced by a not dead object");
3321 }
3322 };
3323
3324 class VerifyObjsInRegionClosure: public ObjectClosure {
3325 private:
3326 G1CollectedHeap* _g1h;
3327 size_t _live_bytes;
3328 HeapRegion *_hr;
3329 VerifyOption _vo;
3330 public:
3331 // _vo == UsePrevMarking -> use "prev" marking information,
3332 // _vo == UseNextMarking -> use "next" marking information,
3333 // _vo == UseMarkWord -> use mark word from object header.
3334 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3335 : _live_bytes(0), _hr(hr), _vo(vo) {
3336 _g1h = G1CollectedHeap::heap();
3337 }
3338 void do_object(oop o) {
3339 VerifyLivenessOopClosure isLive(_g1h, _vo);
3340 assert(o != NULL, "Huh?");
3341 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3342 // If the object is alive according to the mark word,
3343 // then verify that the marking information agrees.
3344 // Note we can't verify the contra-positive of the
3345 // above: if the object is dead (according to the mark
3346 // word), it may not be marked, or may have been marked
3347 // but has since became dead, or may have been allocated
3348 // since the last marking.
3349 if (_vo == VerifyOption_G1UseMarkWord) {
3350 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3351 }
3352
3353 o->oop_iterate_no_header(&isLive);
3354 if (!_hr->obj_allocated_since_prev_marking(o)) {
3355 size_t obj_size = o->size(); // Make sure we don't overflow
3356 _live_bytes += (obj_size * HeapWordSize);
3357 }
3358 }
3359 }
3360 size_t live_bytes() { return _live_bytes; }
3361 };
3362
3363 class VerifyArchiveOopClosure: public OopClosure {
3364 public:
3365 VerifyArchiveOopClosure(HeapRegion *hr) { }
3366 void do_oop(narrowOop *p) { do_oop_work(p); }
3367 void do_oop( oop *p) { do_oop_work(p); }
3368
3369 template <class T> void do_oop_work(T *p) {
3370 oop obj = oopDesc::load_decode_heap_oop(p);
3371 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3372 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3373 p2i(p), p2i(obj)));
3374 }
3375 };
3376
3377 class VerifyArchiveRegionClosure: public ObjectClosure {
3378 public:
3379 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3380 // Verify that all object pointers are to archive regions.
3381 void do_object(oop o) {
3382 VerifyArchiveOopClosure checkOop(NULL);
3383 assert(o != NULL, "Should not be here for NULL oops");
3384 o->oop_iterate_no_header(&checkOop);
3385 }
3386 };
3387
3388 class VerifyRegionClosure: public HeapRegionClosure {
3389 private:
3390 bool _par;
3391 VerifyOption _vo;
3392 bool _failures;
3393 public:
3394 // _vo == UsePrevMarking -> use "prev" marking information,
3395 // _vo == UseNextMarking -> use "next" marking information,
3396 // _vo == UseMarkWord -> use mark word from object header.
3397 VerifyRegionClosure(bool par, VerifyOption vo)
3398 : _par(par),
3399 _vo(vo),
3400 _failures(false) {}
3401
3402 bool failures() {
3403 return _failures;
3404 }
3405
3406 bool doHeapRegion(HeapRegion* r) {
3407 // For archive regions, verify there are no heap pointers to
3408 // non-pinned regions. For all others, verify liveness info.
3409 if (r->is_archive()) {
3410 VerifyArchiveRegionClosure verify_oop_pointers(r);
3411 r->object_iterate(&verify_oop_pointers);
3412 return true;
3413 }
3414 if (!r->is_continues_humongous()) {
3415 bool failures = false;
3416 r->verify(_vo, &failures);
3417 if (failures) {
3418 _failures = true;
3419 } else {
3420 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3421 r->object_iterate(¬_dead_yet_cl);
3422 if (_vo != VerifyOption_G1UseNextMarking) {
3423 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3424 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3425 "max_live_bytes " SIZE_FORMAT " "
3426 "< calculated " SIZE_FORMAT,
3427 p2i(r->bottom()), p2i(r->end()),
3428 r->max_live_bytes(),
3429 not_dead_yet_cl.live_bytes());
3430 _failures = true;
3431 }
3432 } else {
3433 // When vo == UseNextMarking we cannot currently do a sanity
3434 // check on the live bytes as the calculation has not been
3435 // finalized yet.
3436 }
3437 }
3438 }
3439 return false; // stop the region iteration if we hit a failure
3440 }
3441 };
3442
3443 // This is the task used for parallel verification of the heap regions
3444
3445 class G1ParVerifyTask: public AbstractGangTask {
3446 private:
3447 G1CollectedHeap* _g1h;
3448 VerifyOption _vo;
3449 bool _failures;
3450 HeapRegionClaimer _hrclaimer;
3451
3452 public:
3453 // _vo == UsePrevMarking -> use "prev" marking information,
3454 // _vo == UseNextMarking -> use "next" marking information,
3455 // _vo == UseMarkWord -> use mark word from object header.
3456 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3457 AbstractGangTask("Parallel verify task"),
3458 _g1h(g1h),
3459 _vo(vo),
3460 _failures(false),
3461 _hrclaimer(g1h->workers()->active_workers()) {}
3462
3463 bool failures() {
3464 return _failures;
3465 }
3466
3467 void work(uint worker_id) {
3468 HandleMark hm;
3469 VerifyRegionClosure blk(true, _vo);
3470 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3471 if (blk.failures()) {
3472 _failures = true;
3473 }
3474 }
3475 };
3476
3477 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3478 if (SafepointSynchronize::is_at_safepoint()) {
3479 assert(Thread::current()->is_VM_thread(),
3480 "Expected to be executed serially by the VM thread at this point");
3481
3482 if (!silent) { gclog_or_tty->print("Roots "); }
3483 VerifyRootsClosure rootsCl(vo);
3484 VerifyKlassClosure klassCl(this, &rootsCl);
3485 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3486
3487 // We apply the relevant closures to all the oops in the
3488 // system dictionary, class loader data graph, the string table
3489 // and the nmethods in the code cache.
3490 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3491 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3492
3493 {
3494 G1RootProcessor root_processor(this, 1);
3495 root_processor.process_all_roots(&rootsCl,
3496 &cldCl,
3497 &blobsCl);
3498 }
3499
3500 bool failures = rootsCl.failures() || codeRootsCl.failures();
3501
3502 if (vo != VerifyOption_G1UseMarkWord) {
3503 // If we're verifying during a full GC then the region sets
3504 // will have been torn down at the start of the GC. Therefore
3505 // verifying the region sets will fail. So we only verify
3506 // the region sets when not in a full GC.
3507 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3508 verify_region_sets();
3509 }
3510
3511 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3512 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3513
3514 G1ParVerifyTask task(this, vo);
3515 workers()->run_task(&task);
3516 if (task.failures()) {
3517 failures = true;
3518 }
3519
3520 } else {
3521 VerifyRegionClosure blk(false, vo);
3522 heap_region_iterate(&blk);
3523 if (blk.failures()) {
3524 failures = true;
3525 }
3526 }
3527
3528 if (G1StringDedup::is_enabled()) {
3529 if (!silent) gclog_or_tty->print("StrDedup ");
3530 G1StringDedup::verify();
3531 }
3532
3533 if (failures) {
3534 gclog_or_tty->print_cr("Heap:");
3535 // It helps to have the per-region information in the output to
3536 // help us track down what went wrong. This is why we call
3537 // print_extended_on() instead of print_on().
3538 print_extended_on(gclog_or_tty);
3539 gclog_or_tty->cr();
3540 gclog_or_tty->flush();
3541 }
3542 guarantee(!failures, "there should not have been any failures");
3543 } else {
3544 if (!silent) {
3545 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3546 if (G1StringDedup::is_enabled()) {
3547 gclog_or_tty->print(", StrDedup");
3548 }
3549 gclog_or_tty->print(") ");
3550 }
3551 }
3552 }
3553
3554 void G1CollectedHeap::verify(bool silent) {
3555 verify(silent, VerifyOption_G1UsePrevMarking);
3556 }
3557
3558 double G1CollectedHeap::verify(bool guard, const char* msg) {
3559 double verify_time_ms = 0.0;
3560
3561 if (guard && total_collections() >= VerifyGCStartAt) {
3562 double verify_start = os::elapsedTime();
3563 HandleMark hm; // Discard invalid handles created during verification
3564 prepare_for_verify();
3565 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3566 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3567 }
3568
3569 return verify_time_ms;
3570 }
3571
3572 void G1CollectedHeap::verify_before_gc() {
3573 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3574 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3575 }
3576
3577 void G1CollectedHeap::verify_after_gc() {
3578 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3579 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3580 }
3581
3582 class PrintRegionClosure: public HeapRegionClosure {
3583 outputStream* _st;
3584 public:
3585 PrintRegionClosure(outputStream* st) : _st(st) {}
3586 bool doHeapRegion(HeapRegion* r) {
3587 r->print_on(_st);
3588 return false;
3589 }
3590 };
3591
3592 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3593 const HeapRegion* hr,
3594 const VerifyOption vo) const {
3595 switch (vo) {
3596 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3597 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3598 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3599 default: ShouldNotReachHere();
3600 }
3601 return false; // keep some compilers happy
3602 }
3603
3604 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3605 const VerifyOption vo) const {
3606 switch (vo) {
3607 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3608 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3609 case VerifyOption_G1UseMarkWord: {
3610 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3611 return !obj->is_gc_marked() && !hr->is_archive();
3612 }
3613 default: ShouldNotReachHere();
3614 }
3615 return false; // keep some compilers happy
3616 }
3617
3618 void G1CollectedHeap::print_on(outputStream* st) const {
3619 st->print(" %-20s", "garbage-first heap");
3620 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3621 capacity()/K, used_unlocked()/K);
3622 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3623 p2i(_hrm.reserved().start()),
3624 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3625 p2i(_hrm.reserved().end()));
3626 st->cr();
3627 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3628 uint young_regions = _young_list->length();
3629 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3630 (size_t) young_regions * HeapRegion::GrainBytes / K);
3631 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3632 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3633 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3634 st->cr();
3635 MetaspaceAux::print_on(st);
3636 }
3637
3638 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3639 print_on(st);
3640
3641 // Print the per-region information.
3642 st->cr();
3643 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3644 "HS=humongous(starts), HC=humongous(continues), "
3645 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3646 "PTAMS=previous top-at-mark-start, "
3647 "NTAMS=next top-at-mark-start)");
3648 PrintRegionClosure blk(st);
3649 heap_region_iterate(&blk);
3650 }
3651
3652 void G1CollectedHeap::print_on_error(outputStream* st) const {
3653 this->CollectedHeap::print_on_error(st);
3654
3655 if (_cm != NULL) {
3656 st->cr();
3657 _cm->print_on_error(st);
3658 }
3659 }
3660
3661 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3662 workers()->print_worker_threads_on(st);
3663 _cmThread->print_on(st);
3664 st->cr();
3665 _cm->print_worker_threads_on(st);
3666 _cg1r->print_worker_threads_on(st);
3667 if (G1StringDedup::is_enabled()) {
3668 G1StringDedup::print_worker_threads_on(st);
3669 }
3670 }
3671
3672 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3673 workers()->threads_do(tc);
3674 tc->do_thread(_cmThread);
3675 _cg1r->threads_do(tc);
3676 if (G1StringDedup::is_enabled()) {
3677 G1StringDedup::threads_do(tc);
3678 }
3679 }
3680
3681 void G1CollectedHeap::print_tracing_info() const {
3682 // We'll overload this to mean "trace GC pause statistics."
3683 if (TraceYoungGenTime || TraceOldGenTime) {
3684 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3685 // to that.
3686 g1_policy()->print_tracing_info();
3687 }
3688 if (G1SummarizeRSetStats) {
3689 g1_rem_set()->print_summary_info();
3690 }
3691 if (G1SummarizeConcMark) {
3692 concurrent_mark()->print_summary_info();
3693 }
3694 g1_policy()->print_yg_surv_rate_info();
3695 }
3696
3697 #ifndef PRODUCT
3698 // Helpful for debugging RSet issues.
3699
3700 class PrintRSetsClosure : public HeapRegionClosure {
3701 private:
3702 const char* _msg;
3703 size_t _occupied_sum;
3704
3705 public:
3706 bool doHeapRegion(HeapRegion* r) {
3707 HeapRegionRemSet* hrrs = r->rem_set();
3708 size_t occupied = hrrs->occupied();
3709 _occupied_sum += occupied;
3710
3711 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3712 HR_FORMAT_PARAMS(r));
3713 if (occupied == 0) {
3714 gclog_or_tty->print_cr(" RSet is empty");
3715 } else {
3716 hrrs->print();
3717 }
3718 gclog_or_tty->print_cr("----------");
3719 return false;
3720 }
3721
3722 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3723 gclog_or_tty->cr();
3724 gclog_or_tty->print_cr("========================================");
3725 gclog_or_tty->print_cr("%s", msg);
3726 gclog_or_tty->cr();
3727 }
3728
3729 ~PrintRSetsClosure() {
3730 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3731 gclog_or_tty->print_cr("========================================");
3732 gclog_or_tty->cr();
3733 }
3734 };
3735
3736 void G1CollectedHeap::print_cset_rsets() {
3737 PrintRSetsClosure cl("Printing CSet RSets");
3738 collection_set_iterate(&cl);
3739 }
3740
3741 void G1CollectedHeap::print_all_rsets() {
3742 PrintRSetsClosure cl("Printing All RSets");;
3743 heap_region_iterate(&cl);
3744 }
3745 #endif // PRODUCT
3746
3747 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3748 YoungList* young_list = heap()->young_list();
3749
3750 size_t eden_used_bytes = young_list->eden_used_bytes();
3751 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3752
3753 size_t eden_capacity_bytes =
3754 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3755
3756 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3757 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3758 }
3759
3760 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3761 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3762 gc_tracer->report_gc_heap_summary(when, heap_summary);
3763
3764 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3765 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3766 }
3767
3768
3769 G1CollectedHeap* G1CollectedHeap::heap() {
3770 CollectedHeap* heap = Universe::heap();
3771 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3772 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3773 return (G1CollectedHeap*)heap;
3774 }
3775
3776 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3777 // always_do_update_barrier = false;
3778 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3779 // Fill TLAB's and such
3780 accumulate_statistics_all_tlabs();
3781 ensure_parsability(true);
3782
3783 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3784 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3785 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3786 }
3787 }
3788
3789 void G1CollectedHeap::gc_epilogue(bool full) {
3790
3791 if (G1SummarizeRSetStats &&
3792 (G1SummarizeRSetStatsPeriod > 0) &&
3793 // we are at the end of the GC. Total collections has already been increased.
3794 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3795 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3796 }
3797
3798 // FIXME: what is this about?
3799 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3800 // is set.
3801 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3802 "derived pointer present"));
3803 // always_do_update_barrier = true;
3804
3805 resize_all_tlabs();
3806 allocation_context_stats().update(full);
3807
3808 // We have just completed a GC. Update the soft reference
3809 // policy with the new heap occupancy
3810 Universe::update_heap_info_at_gc();
3811 }
3812
3813 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3814 uint gc_count_before,
3815 bool* succeeded,
3816 GCCause::Cause gc_cause) {
3817 assert_heap_not_locked_and_not_at_safepoint();
3818 g1_policy()->record_stop_world_start();
3819 VM_G1IncCollectionPause op(gc_count_before,
3820 word_size,
3821 false, /* should_initiate_conc_mark */
3822 g1_policy()->max_pause_time_ms(),
3823 gc_cause);
3824
3825 op.set_allocation_context(AllocationContext::current());
3826 VMThread::execute(&op);
3827
3828 HeapWord* result = op.result();
3829 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3830 assert(result == NULL || ret_succeeded,
3831 "the result should be NULL if the VM did not succeed");
3832 *succeeded = ret_succeeded;
3833
3834 assert_heap_not_locked();
3835 return result;
3836 }
3837
3838 void
3839 G1CollectedHeap::doConcurrentMark() {
3840 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3841 if (!_cmThread->in_progress()) {
3842 _cmThread->set_started();
3843 CGC_lock->notify();
3844 }
3845 }
3846
3847 size_t G1CollectedHeap::pending_card_num() {
3848 size_t extra_cards = 0;
3849 JavaThread *curr = Threads::first();
3850 while (curr != NULL) {
3851 DirtyCardQueue& dcq = curr->dirty_card_queue();
3852 extra_cards += dcq.size();
3853 curr = curr->next();
3854 }
3855 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3856 size_t buffer_size = dcqs.buffer_size();
3857 size_t buffer_num = dcqs.completed_buffers_num();
3858
3859 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3860 // in bytes - not the number of 'entries'. We need to convert
3861 // into a number of cards.
3862 return (buffer_size * buffer_num + extra_cards) / oopSize;
3863 }
3864
3865 size_t G1CollectedHeap::cards_scanned() {
3866 return g1_rem_set()->cardsScanned();
3867 }
3868
3869 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3870 private:
3871 size_t _total_humongous;
3872 size_t _candidate_humongous;
3873
3874 DirtyCardQueue _dcq;
3875
3876 // We don't nominate objects with many remembered set entries, on
3877 // the assumption that such objects are likely still live.
3878 bool is_remset_small(HeapRegion* region) const {
3879 HeapRegionRemSet* const rset = region->rem_set();
3880 return G1EagerReclaimHumongousObjectsWithStaleRefs
3881 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3882 : rset->is_empty();
3883 }
3884
3885 bool is_typeArray_region(HeapRegion* region) const {
3886 return oop(region->bottom())->is_typeArray();
3887 }
3888
3889 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3890 assert(region->is_starts_humongous(), "Must start a humongous object");
3891
3892 // Candidate selection must satisfy the following constraints
3893 // while concurrent marking is in progress:
3894 //
3895 // * In order to maintain SATB invariants, an object must not be
3896 // reclaimed if it was allocated before the start of marking and
3897 // has not had its references scanned. Such an object must have
3898 // its references (including type metadata) scanned to ensure no
3899 // live objects are missed by the marking process. Objects
3900 // allocated after the start of concurrent marking don't need to
3901 // be scanned.
3902 //
3903 // * An object must not be reclaimed if it is on the concurrent
3904 // mark stack. Objects allocated after the start of concurrent
3905 // marking are never pushed on the mark stack.
3906 //
3907 // Nominating only objects allocated after the start of concurrent
3908 // marking is sufficient to meet both constraints. This may miss
3909 // some objects that satisfy the constraints, but the marking data
3910 // structures don't support efficiently performing the needed
3911 // additional tests or scrubbing of the mark stack.
3912 //
3913 // However, we presently only nominate is_typeArray() objects.
3914 // A humongous object containing references induces remembered
3915 // set entries on other regions. In order to reclaim such an
3916 // object, those remembered sets would need to be cleaned up.
3917 //
3918 // We also treat is_typeArray() objects specially, allowing them
3919 // to be reclaimed even if allocated before the start of
3920 // concurrent mark. For this we rely on mark stack insertion to
3921 // exclude is_typeArray() objects, preventing reclaiming an object
3922 // that is in the mark stack. We also rely on the metadata for
3923 // such objects to be built-in and so ensured to be kept live.
3924 // Frequent allocation and drop of large binary blobs is an
3925 // important use case for eager reclaim, and this special handling
3926 // may reduce needed headroom.
3927
3928 return is_typeArray_region(region) && is_remset_small(region);
3929 }
3930
3931 public:
3932 RegisterHumongousWithInCSetFastTestClosure()
3933 : _total_humongous(0),
3934 _candidate_humongous(0),
3935 _dcq(&JavaThread::dirty_card_queue_set()) {
3936 }
3937
3938 virtual bool doHeapRegion(HeapRegion* r) {
3939 if (!r->is_starts_humongous()) {
3940 return false;
3941 }
3942 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3943
3944 bool is_candidate = humongous_region_is_candidate(g1h, r);
3945 uint rindex = r->hrm_index();
3946 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3947 if (is_candidate) {
3948 _candidate_humongous++;
3949 g1h->register_humongous_region_with_cset(rindex);
3950 // Is_candidate already filters out humongous object with large remembered sets.
3951 // If we have a humongous object with a few remembered sets, we simply flush these
3952 // remembered set entries into the DCQS. That will result in automatic
3953 // re-evaluation of their remembered set entries during the following evacuation
3954 // phase.
3955 if (!r->rem_set()->is_empty()) {
3956 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3957 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3958 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3959 HeapRegionRemSetIterator hrrs(r->rem_set());
3960 size_t card_index;
3961 while (hrrs.has_next(card_index)) {
3962 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3963 // The remembered set might contain references to already freed
3964 // regions. Filter out such entries to avoid failing card table
3965 // verification.
3966 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3967 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3968 *card_ptr = CardTableModRefBS::dirty_card_val();
3969 _dcq.enqueue(card_ptr);
3970 }
3971 }
3972 }
3973 r->rem_set()->clear_locked();
3974 }
3975 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3976 }
3977 _total_humongous++;
3978
3979 return false;
3980 }
3981
3982 size_t total_humongous() const { return _total_humongous; }
3983 size_t candidate_humongous() const { return _candidate_humongous; }
3984
3985 void flush_rem_set_entries() { _dcq.flush(); }
3986 };
3987
3988 void G1CollectedHeap::register_humongous_regions_with_cset() {
3989 if (!G1EagerReclaimHumongousObjects) {
3990 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3991 return;
3992 }
3993 double time = os::elapsed_counter();
3994
3995 // Collect reclaim candidate information and register candidates with cset.
3996 RegisterHumongousWithInCSetFastTestClosure cl;
3997 heap_region_iterate(&cl);
3998
3999 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
4000 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
4001 cl.total_humongous(),
4002 cl.candidate_humongous());
4003 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
4004
4005 // Finally flush all remembered set entries to re-check into the global DCQS.
4006 cl.flush_rem_set_entries();
4007 }
4008
4009 void
4010 G1CollectedHeap::setup_surviving_young_words() {
4011 assert(_surviving_young_words == NULL, "pre-condition");
4012 uint array_length = g1_policy()->young_cset_region_length();
4013 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
4014 if (_surviving_young_words == NULL) {
4015 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
4016 "Not enough space for young surv words summary.");
4017 }
4018 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
4019 #ifdef ASSERT
4020 for (uint i = 0; i < array_length; ++i) {
4021 assert( _surviving_young_words[i] == 0, "memset above" );
4022 }
4023 #endif // !ASSERT
4024 }
4025
4026 void
4027 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
4028 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4029 uint array_length = g1_policy()->young_cset_region_length();
4030 for (uint i = 0; i < array_length; ++i) {
4031 _surviving_young_words[i] += surv_young_words[i];
4032 }
4033 }
4034
4035 void
4036 G1CollectedHeap::cleanup_surviving_young_words() {
4037 guarantee( _surviving_young_words != NULL, "pre-condition" );
4038 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
4039 _surviving_young_words = NULL;
4040 }
4041
4042 #ifdef ASSERT
4043 class VerifyCSetClosure: public HeapRegionClosure {
4044 public:
4045 bool doHeapRegion(HeapRegion* hr) {
4046 // Here we check that the CSet region's RSet is ready for parallel
4047 // iteration. The fields that we'll verify are only manipulated
4048 // when the region is part of a CSet and is collected. Afterwards,
4049 // we reset these fields when we clear the region's RSet (when the
4050 // region is freed) so they are ready when the region is
4051 // re-allocated. The only exception to this is if there's an
4052 // evacuation failure and instead of freeing the region we leave
4053 // it in the heap. In that case, we reset these fields during
4054 // evacuation failure handling.
4055 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
4056
4057 // Here's a good place to add any other checks we'd like to
4058 // perform on CSet regions.
4059 return false;
4060 }
4061 };
4062 #endif // ASSERT
4063
4064 uint G1CollectedHeap::num_task_queues() const {
4065 return _task_queues->size();
4066 }
4067
4068 #if TASKQUEUE_STATS
4069 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
4070 st->print_raw_cr("GC Task Stats");
4071 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
4072 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
4073 }
4074
4075 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
4076 print_taskqueue_stats_hdr(st);
4077
4078 TaskQueueStats totals;
4079 const uint n = num_task_queues();
4080 for (uint i = 0; i < n; ++i) {
4081 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
4082 totals += task_queue(i)->stats;
4083 }
4084 st->print_raw("tot "); totals.print(st); st->cr();
4085
4086 DEBUG_ONLY(totals.verify());
4087 }
4088
4089 void G1CollectedHeap::reset_taskqueue_stats() {
4090 const uint n = num_task_queues();
4091 for (uint i = 0; i < n; ++i) {
4092 task_queue(i)->stats.reset();
4093 }
4094 }
4095 #endif // TASKQUEUE_STATS
4096
4097 void G1CollectedHeap::log_gc_header() {
4098 if (!G1Log::fine()) {
4099 return;
4100 }
4101
4102 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
4103
4104 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
4105 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
4106 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
4107
4108 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
4109 }
4110
4111 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
4112 if (!G1Log::fine()) {
4113 return;
4114 }
4115
4116 if (G1Log::finer()) {
4117 if (evacuation_failed()) {
4118 gclog_or_tty->print(" (to-space exhausted)");
4119 }
4120 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
4121 g1_policy()->phase_times()->note_gc_end();
4122 g1_policy()->phase_times()->print(pause_time_sec);
4123 g1_policy()->print_detailed_heap_transition();
4124 } else {
4125 if (evacuation_failed()) {
4126 gclog_or_tty->print("--");
4127 }
4128 g1_policy()->print_heap_transition();
4129 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
4130 }
4131 gclog_or_tty->flush();
4132 }
4133
4134 void G1CollectedHeap::wait_for_root_region_scanning() {
4135 double scan_wait_start = os::elapsedTime();
4136 // We have to wait until the CM threads finish scanning the
4137 // root regions as it's the only way to ensure that all the
4138 // objects on them have been correctly scanned before we start
4139 // moving them during the GC.
4140 bool waited = _cm->root_regions()->wait_until_scan_finished();
4141 double wait_time_ms = 0.0;
4142 if (waited) {
4143 double scan_wait_end = os::elapsedTime();
4144 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4145 }
4146 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4147 }
4148
4149 bool
4150 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
4151 assert_at_safepoint(true /* should_be_vm_thread */);
4152 guarantee(!is_gc_active(), "collection is not reentrant");
4153
4154 if (GC_locker::check_active_before_gc()) {
4155 return false;
4156 }
4157
4158 _gc_timer_stw->register_gc_start();
4159
4160 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
4161
4162 SvcGCMarker sgcm(SvcGCMarker::MINOR);
4163 ResourceMark rm;
4164
4165 wait_for_root_region_scanning();
4166
4167 G1Log::update_level();
4168 print_heap_before_gc();
4169 trace_heap_before_gc(_gc_tracer_stw);
4170
4171 verify_region_sets_optional();
4172 verify_dirty_young_regions();
4173
4174 // This call will decide whether this pause is an initial-mark
4175 // pause. If it is, during_initial_mark_pause() will return true
4176 // for the duration of this pause.
4177 g1_policy()->decide_on_conc_mark_initiation();
4178
4179 // We do not allow initial-mark to be piggy-backed on a mixed GC.
4180 assert(!collector_state()->during_initial_mark_pause() ||
4181 collector_state()->gcs_are_young(), "sanity");
4182
4183 // We also do not allow mixed GCs during marking.
4184 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4185
4186 // Record whether this pause is an initial mark. When the current
4187 // thread has completed its logging output and it's safe to signal
4188 // the CM thread, the flag's value in the policy has been reset.
4189 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4190
4191 // Inner scope for scope based logging, timers, and stats collection
4192 {
4193 EvacuationInfo evacuation_info;
4194
4195 if (collector_state()->during_initial_mark_pause()) {
4196 // We are about to start a marking cycle, so we increment the
4197 // full collection counter.
4198 increment_old_marking_cycles_started();
4199 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4200 }
4201
4202 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4203
4204 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4205
4206 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4207 workers()->active_workers(),
4208 Threads::number_of_non_daemon_threads());
4209 workers()->set_active_workers(active_workers);
4210
4211 double pause_start_sec = os::elapsedTime();
4212 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4213 log_gc_header();
4214
4215 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4216 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4217
4218 // If the secondary_free_list is not empty, append it to the
4219 // free_list. No need to wait for the cleanup operation to finish;
4220 // the region allocation code will check the secondary_free_list
4221 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4222 // set, skip this step so that the region allocation code has to
4223 // get entries from the secondary_free_list.
4224 if (!G1StressConcRegionFreeing) {
4225 append_secondary_free_list_if_not_empty_with_lock();
4226 }
4227
4228 assert(check_young_list_well_formed(), "young list should be well formed");
4229
4230 // Don't dynamically change the number of GC threads this early. A value of
4231 // 0 is used to indicate serial work. When parallel work is done,
4232 // it will be set.
4233
4234 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4235 IsGCActiveMark x;
4236
4237 gc_prologue(false);
4238 increment_total_collections(false /* full gc */);
4239 increment_gc_time_stamp();
4240
4241 verify_before_gc();
4242
4243 check_bitmaps("GC Start");
4244
4245 COMPILER2_PRESENT(DerivedPointerTable::clear());
4246
4247 // Please see comment in g1CollectedHeap.hpp and
4248 // G1CollectedHeap::ref_processing_init() to see how
4249 // reference processing currently works in G1.
4250
4251 // Enable discovery in the STW reference processor
4252 ref_processor_stw()->enable_discovery();
4253
4254 {
4255 // We want to temporarily turn off discovery by the
4256 // CM ref processor, if necessary, and turn it back on
4257 // on again later if we do. Using a scoped
4258 // NoRefDiscovery object will do this.
4259 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4260
4261 // Forget the current alloc region (we might even choose it to be part
4262 // of the collection set!).
4263 _allocator->release_mutator_alloc_region();
4264
4265 // We should call this after we retire the mutator alloc
4266 // region(s) so that all the ALLOC / RETIRE events are generated
4267 // before the start GC event.
4268 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4269
4270 // This timing is only used by the ergonomics to handle our pause target.
4271 // It is unclear why this should not include the full pause. We will
4272 // investigate this in CR 7178365.
4273 //
4274 // Preserving the old comment here if that helps the investigation:
4275 //
4276 // The elapsed time induced by the start time below deliberately elides
4277 // the possible verification above.
4278 double sample_start_time_sec = os::elapsedTime();
4279
4280 #if YOUNG_LIST_VERBOSE
4281 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4282 _young_list->print();
4283 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4284 #endif // YOUNG_LIST_VERBOSE
4285
4286 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4287
4288 #if YOUNG_LIST_VERBOSE
4289 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4290 _young_list->print();
4291 #endif // YOUNG_LIST_VERBOSE
4292
4293 if (collector_state()->during_initial_mark_pause()) {
4294 concurrent_mark()->checkpointRootsInitialPre();
4295 }
4296
4297 #if YOUNG_LIST_VERBOSE
4298 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4299 _young_list->print();
4300 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4301 #endif // YOUNG_LIST_VERBOSE
4302
4303 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4304
4305 register_humongous_regions_with_cset();
4306
4307 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4308
4309 _cm->note_start_of_gc();
4310 // We call this after finalize_cset() to
4311 // ensure that the CSet has been finalized.
4312 _cm->verify_no_cset_oops();
4313
4314 if (_hr_printer.is_active()) {
4315 HeapRegion* hr = g1_policy()->collection_set();
4316 while (hr != NULL) {
4317 _hr_printer.cset(hr);
4318 hr = hr->next_in_collection_set();
4319 }
4320 }
4321
4322 #ifdef ASSERT
4323 VerifyCSetClosure cl;
4324 collection_set_iterate(&cl);
4325 #endif // ASSERT
4326
4327 setup_surviving_young_words();
4328
4329 // Initialize the GC alloc regions.
4330 _allocator->init_gc_alloc_regions(evacuation_info);
4331
4332 // Actually do the work...
4333 evacuate_collection_set(evacuation_info);
4334
4335 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4336
4337 eagerly_reclaim_humongous_regions();
4338
4339 g1_policy()->clear_collection_set();
4340
4341 cleanup_surviving_young_words();
4342
4343 // Start a new incremental collection set for the next pause.
4344 g1_policy()->start_incremental_cset_building();
4345
4346 clear_cset_fast_test();
4347
4348 _young_list->reset_sampled_info();
4349
4350 // Don't check the whole heap at this point as the
4351 // GC alloc regions from this pause have been tagged
4352 // as survivors and moved on to the survivor list.
4353 // Survivor regions will fail the !is_young() check.
4354 assert(check_young_list_empty(false /* check_heap */),
4355 "young list should be empty");
4356
4357 #if YOUNG_LIST_VERBOSE
4358 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4359 _young_list->print();
4360 #endif // YOUNG_LIST_VERBOSE
4361
4362 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4363 _young_list->first_survivor_region(),
4364 _young_list->last_survivor_region());
4365
4366 _young_list->reset_auxilary_lists();
4367
4368 if (evacuation_failed()) {
4369 set_used(recalculate_used());
4370 if (_archive_allocator != NULL) {
4371 _archive_allocator->clear_used();
4372 }
4373 for (uint i = 0; i < ParallelGCThreads; i++) {
4374 if (_evacuation_failed_info_array[i].has_failed()) {
4375 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4376 }
4377 }
4378 } else {
4379 // The "used" of the the collection set have already been subtracted
4380 // when they were freed. Add in the bytes evacuated.
4381 increase_used(g1_policy()->bytes_copied_during_gc());
4382 }
4383
4384 if (collector_state()->during_initial_mark_pause()) {
4385 // We have to do this before we notify the CM threads that
4386 // they can start working to make sure that all the
4387 // appropriate initialization is done on the CM object.
4388 concurrent_mark()->checkpointRootsInitialPost();
4389 collector_state()->set_mark_in_progress(true);
4390 // Note that we don't actually trigger the CM thread at
4391 // this point. We do that later when we're sure that
4392 // the current thread has completed its logging output.
4393 }
4394
4395 allocate_dummy_regions();
4396
4397 #if YOUNG_LIST_VERBOSE
4398 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4399 _young_list->print();
4400 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4401 #endif // YOUNG_LIST_VERBOSE
4402
4403 _allocator->init_mutator_alloc_region();
4404
4405 {
4406 size_t expand_bytes = g1_policy()->expansion_amount();
4407 if (expand_bytes > 0) {
4408 size_t bytes_before = capacity();
4409 // No need for an ergo verbose message here,
4410 // expansion_amount() does this when it returns a value > 0.
4411 if (!expand(expand_bytes)) {
4412 // We failed to expand the heap. Cannot do anything about it.
4413 }
4414 }
4415 }
4416
4417 // We redo the verification but now wrt to the new CSet which
4418 // has just got initialized after the previous CSet was freed.
4419 _cm->verify_no_cset_oops();
4420 _cm->note_end_of_gc();
4421
4422 // This timing is only used by the ergonomics to handle our pause target.
4423 // It is unclear why this should not include the full pause. We will
4424 // investigate this in CR 7178365.
4425 double sample_end_time_sec = os::elapsedTime();
4426 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4427 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4428
4429 MemoryService::track_memory_usage();
4430
4431 // In prepare_for_verify() below we'll need to scan the deferred
4432 // update buffers to bring the RSets up-to-date if
4433 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4434 // the update buffers we'll probably need to scan cards on the
4435 // regions we just allocated to (i.e., the GC alloc
4436 // regions). However, during the last GC we called
4437 // set_saved_mark() on all the GC alloc regions, so card
4438 // scanning might skip the [saved_mark_word()...top()] area of
4439 // those regions (i.e., the area we allocated objects into
4440 // during the last GC). But it shouldn't. Given that
4441 // saved_mark_word() is conditional on whether the GC time stamp
4442 // on the region is current or not, by incrementing the GC time
4443 // stamp here we invalidate all the GC time stamps on all the
4444 // regions and saved_mark_word() will simply return top() for
4445 // all the regions. This is a nicer way of ensuring this rather
4446 // than iterating over the regions and fixing them. In fact, the
4447 // GC time stamp increment here also ensures that
4448 // saved_mark_word() will return top() between pauses, i.e.,
4449 // during concurrent refinement. So we don't need the
4450 // is_gc_active() check to decided which top to use when
4451 // scanning cards (see CR 7039627).
4452 increment_gc_time_stamp();
4453
4454 verify_after_gc();
4455 check_bitmaps("GC End");
4456
4457 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4458 ref_processor_stw()->verify_no_references_recorded();
4459
4460 // CM reference discovery will be re-enabled if necessary.
4461 }
4462
4463 // We should do this after we potentially expand the heap so
4464 // that all the COMMIT events are generated before the end GC
4465 // event, and after we retire the GC alloc regions so that all
4466 // RETIRE events are generated before the end GC event.
4467 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4468
4469 #ifdef TRACESPINNING
4470 ParallelTaskTerminator::print_termination_counts();
4471 #endif
4472
4473 gc_epilogue(false);
4474 }
4475
4476 // Print the remainder of the GC log output.
4477 log_gc_footer(os::elapsedTime() - pause_start_sec);
4478
4479 // It is not yet to safe to tell the concurrent mark to
4480 // start as we have some optional output below. We don't want the
4481 // output from the concurrent mark thread interfering with this
4482 // logging output either.
4483
4484 _hrm.verify_optional();
4485 verify_region_sets_optional();
4486
4487 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4488 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4489
4490 print_heap_after_gc();
4491 trace_heap_after_gc(_gc_tracer_stw);
4492
4493 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4494 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4495 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4496 // before any GC notifications are raised.
4497 g1mm()->update_sizes();
4498
4499 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4500 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4501 _gc_timer_stw->register_gc_end();
4502 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4503 }
4504 // It should now be safe to tell the concurrent mark thread to start
4505 // without its logging output interfering with the logging output
4506 // that came from the pause.
4507
4508 if (should_start_conc_mark) {
4509 // CAUTION: after the doConcurrentMark() call below,
4510 // the concurrent marking thread(s) could be running
4511 // concurrently with us. Make sure that anything after
4512 // this point does not assume that we are the only GC thread
4513 // running. Note: of course, the actual marking work will
4514 // not start until the safepoint itself is released in
4515 // SuspendibleThreadSet::desynchronize().
4516 doConcurrentMark();
4517 }
4518
4519 return true;
4520 }
4521
4522 void G1CollectedHeap::remove_self_forwarding_pointers() {
4523 double remove_self_forwards_start = os::elapsedTime();
4524
4525 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4526 workers()->run_task(&rsfp_task);
4527
4528 // Now restore saved marks, if any.
4529 for (uint i = 0; i < ParallelGCThreads; i++) {
4530 OopAndMarkOopStack& cur = _preserved_objs[i];
4531 while (!cur.is_empty()) {
4532 OopAndMarkOop elem = cur.pop();
4533 elem.set_mark();
4534 }
4535 cur.clear(true);
4536 }
4537
4538 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4539 }
4540
4541 void G1CollectedHeap::preserve_mark_during_evac_failure(uint queue_num, oop obj, markOop m) {
4542 if (!_evacuation_failed) {
4543 _evacuation_failed = true;
4544 }
4545
4546 _evacuation_failed_info_array[queue_num].register_copy_failure(obj->size());
4547
4548 // We want to call the "for_promotion_failure" version only in the
4549 // case of a promotion failure.
4550 if (m->must_be_preserved_for_promotion_failure(obj)) {
4551 OopAndMarkOop elem(obj, m);
4552 _preserved_objs[queue_num].push(elem);
4553 }
4554 }
4555
4556 void G1ParCopyHelper::mark_object(oop obj) {
4557 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4558
4559 // We know that the object is not moving so it's safe to read its size.
4560 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4561 }
4562
4563 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4564 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4565 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4566 assert(from_obj != to_obj, "should not be self-forwarded");
4567
4568 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4569 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4570
4571 // The object might be in the process of being copied by another
4572 // worker so we cannot trust that its to-space image is
4573 // well-formed. So we have to read its size from its from-space
4574 // image which we know should not be changing.
4575 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4576 }
4577
4578 template <class T>
4579 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4580 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4581 _scanned_klass->record_modified_oops();
4582 }
4583 }
4584
4585 template <G1Barrier barrier, G1Mark do_mark_object>
4586 template <class T>
4587 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4588 T heap_oop = oopDesc::load_heap_oop(p);
4589
4590 if (oopDesc::is_null(heap_oop)) {
4591 return;
4592 }
4593
4594 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4595
4596 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4597
4598 const InCSetState state = _g1->in_cset_state(obj);
4599 if (state.is_in_cset()) {
4600 oop forwardee;
4601 markOop m = obj->mark();
4602 if (m->is_marked()) {
4603 forwardee = (oop) m->decode_pointer();
4604 } else {
4605 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4606 }
4607 assert(forwardee != NULL, "forwardee should not be NULL");
4608 oopDesc::encode_store_heap_oop(p, forwardee);
4609 if (do_mark_object != G1MarkNone && forwardee != obj) {
4610 // If the object is self-forwarded we don't need to explicitly
4611 // mark it, the evacuation failure protocol will do so.
4612 mark_forwarded_object(obj, forwardee);
4613 }
4614
4615 if (barrier == G1BarrierKlass) {
4616 do_klass_barrier(p, forwardee);
4617 }
4618 } else {
4619 if (state.is_humongous()) {
4620 _g1->set_humongous_is_live(obj);
4621 }
4622 // The object is not in collection set. If we're a root scanning
4623 // closure during an initial mark pause then attempt to mark the object.
4624 if (do_mark_object == G1MarkFromRoot) {
4625 mark_object(obj);
4626 }
4627 }
4628 }
4629
4630 class G1ParEvacuateFollowersClosure : public VoidClosure {
4631 protected:
4632 G1CollectedHeap* _g1h;
4633 G1ParScanThreadState* _par_scan_state;
4634 RefToScanQueueSet* _queues;
4635 ParallelTaskTerminator* _terminator;
4636
4637 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4638 RefToScanQueueSet* queues() { return _queues; }
4639 ParallelTaskTerminator* terminator() { return _terminator; }
4640
4641 public:
4642 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4643 G1ParScanThreadState* par_scan_state,
4644 RefToScanQueueSet* queues,
4645 ParallelTaskTerminator* terminator)
4646 : _g1h(g1h), _par_scan_state(par_scan_state),
4647 _queues(queues), _terminator(terminator) {}
4648
4649 void do_void();
4650
4651 private:
4652 inline bool offer_termination();
4653 };
4654
4655 bool G1ParEvacuateFollowersClosure::offer_termination() {
4656 G1ParScanThreadState* const pss = par_scan_state();
4657 pss->start_term_time();
4658 const bool res = terminator()->offer_termination();
4659 pss->end_term_time();
4660 return res;
4661 }
4662
4663 void G1ParEvacuateFollowersClosure::do_void() {
4664 G1ParScanThreadState* const pss = par_scan_state();
4665 pss->trim_queue();
4666 do {
4667 pss->steal_and_trim_queue(queues());
4668 } while (!offer_termination());
4669 }
4670
4671 class G1KlassScanClosure : public KlassClosure {
4672 G1ParCopyHelper* _closure;
4673 bool _process_only_dirty;
4674 int _count;
4675 public:
4676 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4677 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4678 void do_klass(Klass* klass) {
4679 // If the klass has not been dirtied we know that there's
4680 // no references into the young gen and we can skip it.
4681 if (!_process_only_dirty || klass->has_modified_oops()) {
4682 // Clean the klass since we're going to scavenge all the metadata.
4683 klass->clear_modified_oops();
4684
4685 // Tell the closure that this klass is the Klass to scavenge
4686 // and is the one to dirty if oops are left pointing into the young gen.
4687 _closure->set_scanned_klass(klass);
4688
4689 klass->oops_do(_closure);
4690
4691 _closure->set_scanned_klass(NULL);
4692 }
4693 _count++;
4694 }
4695 };
4696
4697 class G1ParTask : public AbstractGangTask {
4698 protected:
4699 G1CollectedHeap* _g1h;
4700 RefToScanQueueSet *_queues;
4701 G1RootProcessor* _root_processor;
4702 ParallelTaskTerminator _terminator;
4703 uint _n_workers;
4704
4705 Mutex _stats_lock;
4706 Mutex* stats_lock() { return &_stats_lock; }
4707
4708 public:
4709 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4710 : AbstractGangTask("G1 collection"),
4711 _g1h(g1h),
4712 _queues(task_queues),
4713 _root_processor(root_processor),
4714 _terminator(n_workers, _queues),
4715 _n_workers(n_workers),
4716 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4717 {}
4718
4719 RefToScanQueueSet* queues() { return _queues; }
4720
4721 RefToScanQueue *work_queue(int i) {
4722 return queues()->queue(i);
4723 }
4724
4725 ParallelTaskTerminator* terminator() { return &_terminator; }
4726
4727 // Helps out with CLD processing.
4728 //
4729 // During InitialMark we need to:
4730 // 1) Scavenge all CLDs for the young GC.
4731 // 2) Mark all objects directly reachable from strong CLDs.
4732 template <G1Mark do_mark_object>
4733 class G1CLDClosure : public CLDClosure {
4734 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4735 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4736 G1KlassScanClosure _klass_in_cld_closure;
4737 bool _claim;
4738
4739 public:
4740 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4741 bool only_young, bool claim)
4742 : _oop_closure(oop_closure),
4743 _oop_in_klass_closure(oop_closure->g1(),
4744 oop_closure->pss(),
4745 oop_closure->rp()),
4746 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4747 _claim(claim) {
4748
4749 }
4750
4751 void do_cld(ClassLoaderData* cld) {
4752 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4753 }
4754 };
4755
4756 void work(uint worker_id) {
4757 if (worker_id >= _n_workers) return; // no work needed this round
4758
4759 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4760
4761 {
4762 ResourceMark rm;
4763 HandleMark hm;
4764
4765 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4766
4767 G1ParScanThreadState pss(_g1h, worker_id, rp);
4768
4769 bool only_young = _g1h->collector_state()->gcs_are_young();
4770
4771 // Non-IM young GC.
4772 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4773 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4774 only_young, // Only process dirty klasses.
4775 false); // No need to claim CLDs.
4776 // IM young GC.
4777 // Strong roots closures.
4778 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4779 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4780 false, // Process all klasses.
4781 true); // Need to claim CLDs.
4782 // Weak roots closures.
4783 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4784 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4785 false, // Process all klasses.
4786 true); // Need to claim CLDs.
4787
4788 OopClosure* strong_root_cl;
4789 OopClosure* weak_root_cl;
4790 CLDClosure* strong_cld_cl;
4791 CLDClosure* weak_cld_cl;
4792
4793 bool trace_metadata = false;
4794
4795 if (_g1h->collector_state()->during_initial_mark_pause()) {
4796 // We also need to mark copied objects.
4797 strong_root_cl = &scan_mark_root_cl;
4798 strong_cld_cl = &scan_mark_cld_cl;
4799 if (ClassUnloadingWithConcurrentMark) {
4800 weak_root_cl = &scan_mark_weak_root_cl;
4801 weak_cld_cl = &scan_mark_weak_cld_cl;
4802 trace_metadata = true;
4803 } else {
4804 weak_root_cl = &scan_mark_root_cl;
4805 weak_cld_cl = &scan_mark_cld_cl;
4806 }
4807 } else {
4808 strong_root_cl = &scan_only_root_cl;
4809 weak_root_cl = &scan_only_root_cl;
4810 strong_cld_cl = &scan_only_cld_cl;
4811 weak_cld_cl = &scan_only_cld_cl;
4812 }
4813
4814 pss.start_strong_roots();
4815
4816 _root_processor->evacuate_roots(strong_root_cl,
4817 weak_root_cl,
4818 strong_cld_cl,
4819 weak_cld_cl,
4820 trace_metadata,
4821 worker_id);
4822
4823 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4824 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4825 weak_root_cl,
4826 worker_id);
4827 pss.end_strong_roots();
4828
4829 {
4830 double start = os::elapsedTime();
4831 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4832 evac.do_void();
4833 double elapsed_sec = os::elapsedTime() - start;
4834 double term_sec = pss.term_time();
4835 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4836 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4837 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4838 }
4839 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4840 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4841
4842 if (PrintTerminationStats) {
4843 MutexLocker x(stats_lock());
4844 pss.print_termination_stats(worker_id);
4845 }
4846
4847 assert(pss.queue_is_empty(), "should be empty");
4848
4849 // Close the inner scope so that the ResourceMark and HandleMark
4850 // destructors are executed here and are included as part of the
4851 // "GC Worker Time".
4852 }
4853 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4854 }
4855 };
4856
4857 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4858 private:
4859 BoolObjectClosure* _is_alive;
4860 int _initial_string_table_size;
4861 int _initial_symbol_table_size;
4862
4863 bool _process_strings;
4864 int _strings_processed;
4865 int _strings_removed;
4866
4867 bool _process_symbols;
4868 int _symbols_processed;
4869 int _symbols_removed;
4870
4871 public:
4872 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4873 AbstractGangTask("String/Symbol Unlinking"),
4874 _is_alive(is_alive),
4875 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4876 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4877
4878 _initial_string_table_size = StringTable::the_table()->table_size();
4879 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4880 if (process_strings) {
4881 StringTable::clear_parallel_claimed_index();
4882 }
4883 if (process_symbols) {
4884 SymbolTable::clear_parallel_claimed_index();
4885 }
4886 }
4887
4888 ~G1StringSymbolTableUnlinkTask() {
4889 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4890 err_msg("claim value %d after unlink less than initial string table size %d",
4891 StringTable::parallel_claimed_index(), _initial_string_table_size));
4892 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4893 err_msg("claim value %d after unlink less than initial symbol table size %d",
4894 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4895
4896 if (G1TraceStringSymbolTableScrubbing) {
4897 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4898 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4899 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4900 strings_processed(), strings_removed(),
4901 symbols_processed(), symbols_removed());
4902 }
4903 }
4904
4905 void work(uint worker_id) {
4906 int strings_processed = 0;
4907 int strings_removed = 0;
4908 int symbols_processed = 0;
4909 int symbols_removed = 0;
4910 if (_process_strings) {
4911 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4912 Atomic::add(strings_processed, &_strings_processed);
4913 Atomic::add(strings_removed, &_strings_removed);
4914 }
4915 if (_process_symbols) {
4916 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4917 Atomic::add(symbols_processed, &_symbols_processed);
4918 Atomic::add(symbols_removed, &_symbols_removed);
4919 }
4920 }
4921
4922 size_t strings_processed() const { return (size_t)_strings_processed; }
4923 size_t strings_removed() const { return (size_t)_strings_removed; }
4924
4925 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4926 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4927 };
4928
4929 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4930 private:
4931 static Monitor* _lock;
4932
4933 BoolObjectClosure* const _is_alive;
4934 const bool _unloading_occurred;
4935 const uint _num_workers;
4936
4937 // Variables used to claim nmethods.
4938 nmethod* _first_nmethod;
4939 volatile nmethod* _claimed_nmethod;
4940
4941 // The list of nmethods that need to be processed by the second pass.
4942 volatile nmethod* _postponed_list;
4943 volatile uint _num_entered_barrier;
4944
4945 public:
4946 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4947 _is_alive(is_alive),
4948 _unloading_occurred(unloading_occurred),
4949 _num_workers(num_workers),
4950 _first_nmethod(NULL),
4951 _claimed_nmethod(NULL),
4952 _postponed_list(NULL),
4953 _num_entered_barrier(0)
4954 {
4955 nmethod::increase_unloading_clock();
4956 // Get first alive nmethod
4957 NMethodIterator iter = NMethodIterator();
4958 if(iter.next_alive()) {
4959 _first_nmethod = iter.method();
4960 }
4961 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4962 }
4963
4964 ~G1CodeCacheUnloadingTask() {
4965 CodeCache::verify_clean_inline_caches();
4966
4967 CodeCache::set_needs_cache_clean(false);
4968 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4969
4970 CodeCache::verify_icholder_relocations();
4971 }
4972
4973 private:
4974 void add_to_postponed_list(nmethod* nm) {
4975 nmethod* old;
4976 do {
4977 old = (nmethod*)_postponed_list;
4978 nm->set_unloading_next(old);
4979 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4980 }
4981
4982 void clean_nmethod(nmethod* nm) {
4983 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4984
4985 if (postponed) {
4986 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4987 add_to_postponed_list(nm);
4988 }
4989
4990 // Mark that this thread has been cleaned/unloaded.
4991 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4992 nm->set_unloading_clock(nmethod::global_unloading_clock());
4993 }
4994
4995 void clean_nmethod_postponed(nmethod* nm) {
4996 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4997 }
4998
4999 static const int MaxClaimNmethods = 16;
5000
5001 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5002 nmethod* first;
5003 NMethodIterator last;
5004
5005 do {
5006 *num_claimed_nmethods = 0;
5007
5008 first = (nmethod*)_claimed_nmethod;
5009 last = NMethodIterator(first);
5010
5011 if (first != NULL) {
5012
5013 for (int i = 0; i < MaxClaimNmethods; i++) {
5014 if (!last.next_alive()) {
5015 break;
5016 }
5017 claimed_nmethods[i] = last.method();
5018 (*num_claimed_nmethods)++;
5019 }
5020 }
5021
5022 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
5023 }
5024
5025 nmethod* claim_postponed_nmethod() {
5026 nmethod* claim;
5027 nmethod* next;
5028
5029 do {
5030 claim = (nmethod*)_postponed_list;
5031 if (claim == NULL) {
5032 return NULL;
5033 }
5034
5035 next = claim->unloading_next();
5036
5037 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5038
5039 return claim;
5040 }
5041
5042 public:
5043 // Mark that we're done with the first pass of nmethod cleaning.
5044 void barrier_mark(uint worker_id) {
5045 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5046 _num_entered_barrier++;
5047 if (_num_entered_barrier == _num_workers) {
5048 ml.notify_all();
5049 }
5050 }
5051
5052 // See if we have to wait for the other workers to
5053 // finish their first-pass nmethod cleaning work.
5054 void barrier_wait(uint worker_id) {
5055 if (_num_entered_barrier < _num_workers) {
5056 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5057 while (_num_entered_barrier < _num_workers) {
5058 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5059 }
5060 }
5061 }
5062
5063 // Cleaning and unloading of nmethods. Some work has to be postponed
5064 // to the second pass, when we know which nmethods survive.
5065 void work_first_pass(uint worker_id) {
5066 // The first nmethods is claimed by the first worker.
5067 if (worker_id == 0 && _first_nmethod != NULL) {
5068 clean_nmethod(_first_nmethod);
5069 _first_nmethod = NULL;
5070 }
5071
5072 int num_claimed_nmethods;
5073 nmethod* claimed_nmethods[MaxClaimNmethods];
5074
5075 while (true) {
5076 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5077
5078 if (num_claimed_nmethods == 0) {
5079 break;
5080 }
5081
5082 for (int i = 0; i < num_claimed_nmethods; i++) {
5083 clean_nmethod(claimed_nmethods[i]);
5084 }
5085 }
5086 }
5087
5088 void work_second_pass(uint worker_id) {
5089 nmethod* nm;
5090 // Take care of postponed nmethods.
5091 while ((nm = claim_postponed_nmethod()) != NULL) {
5092 clean_nmethod_postponed(nm);
5093 }
5094 }
5095 };
5096
5097 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
5098
5099 class G1KlassCleaningTask : public StackObj {
5100 BoolObjectClosure* _is_alive;
5101 volatile jint _clean_klass_tree_claimed;
5102 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5103
5104 public:
5105 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5106 _is_alive(is_alive),
5107 _clean_klass_tree_claimed(0),
5108 _klass_iterator() {
5109 }
5110
5111 private:
5112 bool claim_clean_klass_tree_task() {
5113 if (_clean_klass_tree_claimed) {
5114 return false;
5115 }
5116
5117 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5118 }
5119
5120 InstanceKlass* claim_next_klass() {
5121 Klass* klass;
5122 do {
5123 klass =_klass_iterator.next_klass();
5124 } while (klass != NULL && !klass->oop_is_instance());
5125
5126 return (InstanceKlass*)klass;
5127 }
5128
5129 public:
5130
5131 void clean_klass(InstanceKlass* ik) {
5132 ik->clean_implementors_list(_is_alive);
5133 ik->clean_method_data(_is_alive);
5134
5135 // G1 specific cleanup work that has
5136 // been moved here to be done in parallel.
5137 ik->clean_dependent_nmethods();
5138 }
5139
5140 void work() {
5141 ResourceMark rm;
5142
5143 // One worker will clean the subklass/sibling klass tree.
5144 if (claim_clean_klass_tree_task()) {
5145 Klass::clean_subklass_tree(_is_alive);
5146 }
5147
5148 // All workers will help cleaning the classes,
5149 InstanceKlass* klass;
5150 while ((klass = claim_next_klass()) != NULL) {
5151 clean_klass(klass);
5152 }
5153 }
5154 };
5155
5156 // To minimize the remark pause times, the tasks below are done in parallel.
5157 class G1ParallelCleaningTask : public AbstractGangTask {
5158 private:
5159 G1StringSymbolTableUnlinkTask _string_symbol_task;
5160 G1CodeCacheUnloadingTask _code_cache_task;
5161 G1KlassCleaningTask _klass_cleaning_task;
5162
5163 public:
5164 // The constructor is run in the VMThread.
5165 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5166 AbstractGangTask("Parallel Cleaning"),
5167 _string_symbol_task(is_alive, process_strings, process_symbols),
5168 _code_cache_task(num_workers, is_alive, unloading_occurred),
5169 _klass_cleaning_task(is_alive) {
5170 }
5171
5172 // The parallel work done by all worker threads.
5173 void work(uint worker_id) {
5174 // Do first pass of code cache cleaning.
5175 _code_cache_task.work_first_pass(worker_id);
5176
5177 // Let the threads mark that the first pass is done.
5178 _code_cache_task.barrier_mark(worker_id);
5179
5180 // Clean the Strings and Symbols.
5181 _string_symbol_task.work(worker_id);
5182
5183 // Wait for all workers to finish the first code cache cleaning pass.
5184 _code_cache_task.barrier_wait(worker_id);
5185
5186 // Do the second code cache cleaning work, which realize on
5187 // the liveness information gathered during the first pass.
5188 _code_cache_task.work_second_pass(worker_id);
5189
5190 // Clean all klasses that were not unloaded.
5191 _klass_cleaning_task.work();
5192 }
5193 };
5194
5195
5196 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5197 bool process_strings,
5198 bool process_symbols,
5199 bool class_unloading_occurred) {
5200 uint n_workers = workers()->active_workers();
5201
5202 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5203 n_workers, class_unloading_occurred);
5204 workers()->run_task(&g1_unlink_task);
5205 }
5206
5207 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5208 bool process_strings, bool process_symbols) {
5209 {
5210 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5211 workers()->run_task(&g1_unlink_task);
5212 }
5213
5214 if (G1StringDedup::is_enabled()) {
5215 G1StringDedup::unlink(is_alive);
5216 }
5217 }
5218
5219 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5220 private:
5221 DirtyCardQueueSet* _queue;
5222 public:
5223 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5224
5225 virtual void work(uint worker_id) {
5226 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5227 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5228
5229 RedirtyLoggedCardTableEntryClosure cl;
5230 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5231
5232 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5233 }
5234 };
5235
5236 void G1CollectedHeap::redirty_logged_cards() {
5237 double redirty_logged_cards_start = os::elapsedTime();
5238
5239 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5240 dirty_card_queue_set().reset_for_par_iteration();
5241 workers()->run_task(&redirty_task);
5242
5243 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5244 dcq.merge_bufferlists(&dirty_card_queue_set());
5245 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5246
5247 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5248 }
5249
5250 // Weak Reference Processing support
5251
5252 // An always "is_alive" closure that is used to preserve referents.
5253 // If the object is non-null then it's alive. Used in the preservation
5254 // of referent objects that are pointed to by reference objects
5255 // discovered by the CM ref processor.
5256 class G1AlwaysAliveClosure: public BoolObjectClosure {
5257 G1CollectedHeap* _g1;
5258 public:
5259 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5260 bool do_object_b(oop p) {
5261 if (p != NULL) {
5262 return true;
5263 }
5264 return false;
5265 }
5266 };
5267
5268 bool G1STWIsAliveClosure::do_object_b(oop p) {
5269 // An object is reachable if it is outside the collection set,
5270 // or is inside and copied.
5271 return !_g1->obj_in_cs(p) || p->is_forwarded();
5272 }
5273
5274 // Non Copying Keep Alive closure
5275 class G1KeepAliveClosure: public OopClosure {
5276 G1CollectedHeap* _g1;
5277 public:
5278 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5279 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5280 void do_oop(oop* p) {
5281 oop obj = *p;
5282 assert(obj != NULL, "the caller should have filtered out NULL values");
5283
5284 const InCSetState cset_state = _g1->in_cset_state(obj);
5285 if (!cset_state.is_in_cset_or_humongous()) {
5286 return;
5287 }
5288 if (cset_state.is_in_cset()) {
5289 assert( obj->is_forwarded(), "invariant" );
5290 *p = obj->forwardee();
5291 } else {
5292 assert(!obj->is_forwarded(), "invariant" );
5293 assert(cset_state.is_humongous(),
5294 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5295 _g1->set_humongous_is_live(obj);
5296 }
5297 }
5298 };
5299
5300 // Copying Keep Alive closure - can be called from both
5301 // serial and parallel code as long as different worker
5302 // threads utilize different G1ParScanThreadState instances
5303 // and different queues.
5304
5305 class G1CopyingKeepAliveClosure: public OopClosure {
5306 G1CollectedHeap* _g1h;
5307 OopClosure* _copy_non_heap_obj_cl;
5308 G1ParScanThreadState* _par_scan_state;
5309
5310 public:
5311 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5312 OopClosure* non_heap_obj_cl,
5313 G1ParScanThreadState* pss):
5314 _g1h(g1h),
5315 _copy_non_heap_obj_cl(non_heap_obj_cl),
5316 _par_scan_state(pss)
5317 {}
5318
5319 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5320 virtual void do_oop( oop* p) { do_oop_work(p); }
5321
5322 template <class T> void do_oop_work(T* p) {
5323 oop obj = oopDesc::load_decode_heap_oop(p);
5324
5325 if (_g1h->is_in_cset_or_humongous(obj)) {
5326 // If the referent object has been forwarded (either copied
5327 // to a new location or to itself in the event of an
5328 // evacuation failure) then we need to update the reference
5329 // field and, if both reference and referent are in the G1
5330 // heap, update the RSet for the referent.
5331 //
5332 // If the referent has not been forwarded then we have to keep
5333 // it alive by policy. Therefore we have copy the referent.
5334 //
5335 // If the reference field is in the G1 heap then we can push
5336 // on the PSS queue. When the queue is drained (after each
5337 // phase of reference processing) the object and it's followers
5338 // will be copied, the reference field set to point to the
5339 // new location, and the RSet updated. Otherwise we need to
5340 // use the the non-heap or metadata closures directly to copy
5341 // the referent object and update the pointer, while avoiding
5342 // updating the RSet.
5343
5344 if (_g1h->is_in_g1_reserved(p)) {
5345 _par_scan_state->push_on_queue(p);
5346 } else {
5347 assert(!Metaspace::contains((const void*)p),
5348 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5349 _copy_non_heap_obj_cl->do_oop(p);
5350 }
5351 }
5352 }
5353 };
5354
5355 // Serial drain queue closure. Called as the 'complete_gc'
5356 // closure for each discovered list in some of the
5357 // reference processing phases.
5358
5359 class G1STWDrainQueueClosure: public VoidClosure {
5360 protected:
5361 G1CollectedHeap* _g1h;
5362 G1ParScanThreadState* _par_scan_state;
5363
5364 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5365
5366 public:
5367 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5368 _g1h(g1h),
5369 _par_scan_state(pss)
5370 { }
5371
5372 void do_void() {
5373 G1ParScanThreadState* const pss = par_scan_state();
5374 pss->trim_queue();
5375 }
5376 };
5377
5378 // Parallel Reference Processing closures
5379
5380 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5381 // processing during G1 evacuation pauses.
5382
5383 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5384 private:
5385 G1CollectedHeap* _g1h;
5386 RefToScanQueueSet* _queues;
5387 FlexibleWorkGang* _workers;
5388 uint _active_workers;
5389
5390 public:
5391 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5392 FlexibleWorkGang* workers,
5393 RefToScanQueueSet *task_queues,
5394 uint n_workers) :
5395 _g1h(g1h),
5396 _queues(task_queues),
5397 _workers(workers),
5398 _active_workers(n_workers)
5399 {
5400 assert(n_workers > 0, "shouldn't call this otherwise");
5401 }
5402
5403 // Executes the given task using concurrent marking worker threads.
5404 virtual void execute(ProcessTask& task);
5405 virtual void execute(EnqueueTask& task);
5406 };
5407
5408 // Gang task for possibly parallel reference processing
5409
5410 class G1STWRefProcTaskProxy: public AbstractGangTask {
5411 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5412 ProcessTask& _proc_task;
5413 G1CollectedHeap* _g1h;
5414 RefToScanQueueSet *_task_queues;
5415 ParallelTaskTerminator* _terminator;
5416
5417 public:
5418 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5419 G1CollectedHeap* g1h,
5420 RefToScanQueueSet *task_queues,
5421 ParallelTaskTerminator* terminator) :
5422 AbstractGangTask("Process reference objects in parallel"),
5423 _proc_task(proc_task),
5424 _g1h(g1h),
5425 _task_queues(task_queues),
5426 _terminator(terminator)
5427 {}
5428
5429 virtual void work(uint worker_id) {
5430 // The reference processing task executed by a single worker.
5431 ResourceMark rm;
5432 HandleMark hm;
5433
5434 G1STWIsAliveClosure is_alive(_g1h);
5435
5436 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5437
5438 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5439
5440 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5441
5442 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5443
5444 if (_g1h->collector_state()->during_initial_mark_pause()) {
5445 // We also need to mark copied objects.
5446 copy_non_heap_cl = ©_mark_non_heap_cl;
5447 }
5448
5449 // Keep alive closure.
5450 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5451
5452 // Complete GC closure
5453 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5454
5455 // Call the reference processing task's work routine.
5456 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5457
5458 // Note we cannot assert that the refs array is empty here as not all
5459 // of the processing tasks (specifically phase2 - pp2_work) execute
5460 // the complete_gc closure (which ordinarily would drain the queue) so
5461 // the queue may not be empty.
5462 }
5463 };
5464
5465 // Driver routine for parallel reference processing.
5466 // Creates an instance of the ref processing gang
5467 // task and has the worker threads execute it.
5468 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5469 assert(_workers != NULL, "Need parallel worker threads.");
5470
5471 ParallelTaskTerminator terminator(_active_workers, _queues);
5472 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5473
5474 _workers->run_task(&proc_task_proxy);
5475 }
5476
5477 // Gang task for parallel reference enqueueing.
5478
5479 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5480 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5481 EnqueueTask& _enq_task;
5482
5483 public:
5484 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5485 AbstractGangTask("Enqueue reference objects in parallel"),
5486 _enq_task(enq_task)
5487 { }
5488
5489 virtual void work(uint worker_id) {
5490 _enq_task.work(worker_id);
5491 }
5492 };
5493
5494 // Driver routine for parallel reference enqueueing.
5495 // Creates an instance of the ref enqueueing gang
5496 // task and has the worker threads execute it.
5497
5498 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5499 assert(_workers != NULL, "Need parallel worker threads.");
5500
5501 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5502
5503 _workers->run_task(&enq_task_proxy);
5504 }
5505
5506 // End of weak reference support closures
5507
5508 // Abstract task used to preserve (i.e. copy) any referent objects
5509 // that are in the collection set and are pointed to by reference
5510 // objects discovered by the CM ref processor.
5511
5512 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5513 protected:
5514 G1CollectedHeap* _g1h;
5515 RefToScanQueueSet *_queues;
5516 ParallelTaskTerminator _terminator;
5517 uint _n_workers;
5518
5519 public:
5520 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5521 AbstractGangTask("ParPreserveCMReferents"),
5522 _g1h(g1h),
5523 _queues(task_queues),
5524 _terminator(workers, _queues),
5525 _n_workers(workers)
5526 { }
5527
5528 void work(uint worker_id) {
5529 ResourceMark rm;
5530 HandleMark hm;
5531
5532 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5533 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5534
5535 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5536
5537 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5538
5539 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5540
5541 if (_g1h->collector_state()->during_initial_mark_pause()) {
5542 // We also need to mark copied objects.
5543 copy_non_heap_cl = ©_mark_non_heap_cl;
5544 }
5545
5546 // Is alive closure
5547 G1AlwaysAliveClosure always_alive(_g1h);
5548
5549 // Copying keep alive closure. Applied to referent objects that need
5550 // to be copied.
5551 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5552
5553 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5554
5555 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5556 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5557
5558 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5559 // So this must be true - but assert just in case someone decides to
5560 // change the worker ids.
5561 assert(worker_id < limit, "sanity");
5562 assert(!rp->discovery_is_atomic(), "check this code");
5563
5564 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5565 for (uint idx = worker_id; idx < limit; idx += stride) {
5566 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5567
5568 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5569 while (iter.has_next()) {
5570 // Since discovery is not atomic for the CM ref processor, we
5571 // can see some null referent objects.
5572 iter.load_ptrs(DEBUG_ONLY(true));
5573 oop ref = iter.obj();
5574
5575 // This will filter nulls.
5576 if (iter.is_referent_alive()) {
5577 iter.make_referent_alive();
5578 }
5579 iter.move_to_next();
5580 }
5581 }
5582
5583 // Drain the queue - which may cause stealing
5584 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5585 drain_queue.do_void();
5586 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5587 assert(pss.queue_is_empty(), "should be");
5588 }
5589 };
5590
5591 // Weak Reference processing during an evacuation pause (part 1).
5592 void G1CollectedHeap::process_discovered_references() {
5593 double ref_proc_start = os::elapsedTime();
5594
5595 ReferenceProcessor* rp = _ref_processor_stw;
5596 assert(rp->discovery_enabled(), "should have been enabled");
5597
5598 // Any reference objects, in the collection set, that were 'discovered'
5599 // by the CM ref processor should have already been copied (either by
5600 // applying the external root copy closure to the discovered lists, or
5601 // by following an RSet entry).
5602 //
5603 // But some of the referents, that are in the collection set, that these
5604 // reference objects point to may not have been copied: the STW ref
5605 // processor would have seen that the reference object had already
5606 // been 'discovered' and would have skipped discovering the reference,
5607 // but would not have treated the reference object as a regular oop.
5608 // As a result the copy closure would not have been applied to the
5609 // referent object.
5610 //
5611 // We need to explicitly copy these referent objects - the references
5612 // will be processed at the end of remarking.
5613 //
5614 // We also need to do this copying before we process the reference
5615 // objects discovered by the STW ref processor in case one of these
5616 // referents points to another object which is also referenced by an
5617 // object discovered by the STW ref processor.
5618
5619 uint no_of_gc_workers = workers()->active_workers();
5620
5621 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5622 no_of_gc_workers,
5623 _task_queues);
5624
5625 workers()->run_task(&keep_cm_referents);
5626
5627 // Closure to test whether a referent is alive.
5628 G1STWIsAliveClosure is_alive(this);
5629
5630 // Even when parallel reference processing is enabled, the processing
5631 // of JNI refs is serial and performed serially by the current thread
5632 // rather than by a worker. The following PSS will be used for processing
5633 // JNI refs.
5634
5635 // Use only a single queue for this PSS.
5636 G1ParScanThreadState pss(this, 0, NULL);
5637 assert(pss.queue_is_empty(), "pre-condition");
5638
5639 // We do not embed a reference processor in the copying/scanning
5640 // closures while we're actually processing the discovered
5641 // reference objects.
5642
5643 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5644
5645 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5646
5647 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5648
5649 if (collector_state()->during_initial_mark_pause()) {
5650 // We also need to mark copied objects.
5651 copy_non_heap_cl = ©_mark_non_heap_cl;
5652 }
5653
5654 // Keep alive closure.
5655 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5656
5657 // Serial Complete GC closure
5658 G1STWDrainQueueClosure drain_queue(this, &pss);
5659
5660 // Setup the soft refs policy...
5661 rp->setup_policy(false);
5662
5663 ReferenceProcessorStats stats;
5664 if (!rp->processing_is_mt()) {
5665 // Serial reference processing...
5666 stats = rp->process_discovered_references(&is_alive,
5667 &keep_alive,
5668 &drain_queue,
5669 NULL,
5670 _gc_timer_stw,
5671 _gc_tracer_stw->gc_id());
5672 } else {
5673 // Parallel reference processing
5674 assert(rp->num_q() == no_of_gc_workers, "sanity");
5675 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5676
5677 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5678 stats = rp->process_discovered_references(&is_alive,
5679 &keep_alive,
5680 &drain_queue,
5681 &par_task_executor,
5682 _gc_timer_stw,
5683 _gc_tracer_stw->gc_id());
5684 }
5685
5686 _gc_tracer_stw->report_gc_reference_stats(stats);
5687
5688 // We have completed copying any necessary live referent objects.
5689 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5690
5691 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5692 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5693 }
5694
5695 // Weak Reference processing during an evacuation pause (part 2).
5696 void G1CollectedHeap::enqueue_discovered_references() {
5697 double ref_enq_start = os::elapsedTime();
5698
5699 ReferenceProcessor* rp = _ref_processor_stw;
5700 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5701
5702 // Now enqueue any remaining on the discovered lists on to
5703 // the pending list.
5704 if (!rp->processing_is_mt()) {
5705 // Serial reference processing...
5706 rp->enqueue_discovered_references();
5707 } else {
5708 // Parallel reference enqueueing
5709
5710 uint n_workers = workers()->active_workers();
5711
5712 assert(rp->num_q() == n_workers, "sanity");
5713 assert(n_workers <= rp->max_num_q(), "sanity");
5714
5715 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5716 rp->enqueue_discovered_references(&par_task_executor);
5717 }
5718
5719 rp->verify_no_references_recorded();
5720 assert(!rp->discovery_enabled(), "should have been disabled");
5721
5722 // FIXME
5723 // CM's reference processing also cleans up the string and symbol tables.
5724 // Should we do that here also? We could, but it is a serial operation
5725 // and could significantly increase the pause time.
5726
5727 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5728 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5729 }
5730
5731 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5732 _expand_heap_after_alloc_failure = true;
5733 _evacuation_failed = false;
5734
5735 // Should G1EvacuationFailureALot be in effect for this GC?
5736 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5737
5738 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5739
5740 // Disable the hot card cache.
5741 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5742 hot_card_cache->reset_hot_cache_claimed_index();
5743 hot_card_cache->set_use_cache(false);
5744
5745 const uint n_workers = workers()->active_workers();
5746
5747 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5748 double start_par_time_sec = os::elapsedTime();
5749 double end_par_time_sec;
5750
5751 {
5752 G1RootProcessor root_processor(this, n_workers);
5753 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5754 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5755 if (collector_state()->during_initial_mark_pause()) {
5756 ClassLoaderDataGraph::clear_claimed_marks();
5757 }
5758
5759 // The individual threads will set their evac-failure closures.
5760 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5761
5762 workers()->run_task(&g1_par_task);
5763 end_par_time_sec = os::elapsedTime();
5764
5765 // Closing the inner scope will execute the destructor
5766 // for the G1RootProcessor object. We record the current
5767 // elapsed time before closing the scope so that time
5768 // taken for the destructor is NOT included in the
5769 // reported parallel time.
5770 }
5771
5772 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5773
5774 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5775 phase_times->record_par_time(par_time_ms);
5776
5777 double code_root_fixup_time_ms =
5778 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5779 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5780
5781 // Process any discovered reference objects - we have
5782 // to do this _before_ we retire the GC alloc regions
5783 // as we may have to copy some 'reachable' referent
5784 // objects (and their reachable sub-graphs) that were
5785 // not copied during the pause.
5786 process_discovered_references();
5787
5788 if (G1StringDedup::is_enabled()) {
5789 double fixup_start = os::elapsedTime();
5790
5791 G1STWIsAliveClosure is_alive(this);
5792 G1KeepAliveClosure keep_alive(this);
5793 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5794
5795 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5796 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5797 }
5798
5799 _allocator->release_gc_alloc_regions(evacuation_info);
5800 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5801
5802 // Reset and re-enable the hot card cache.
5803 // Note the counts for the cards in the regions in the
5804 // collection set are reset when the collection set is freed.
5805 hot_card_cache->reset_hot_cache();
5806 hot_card_cache->set_use_cache(true);
5807
5808 purge_code_root_memory();
5809
5810 if (evacuation_failed()) {
5811 remove_self_forwarding_pointers();
5812
5813 // Reset the G1EvacuationFailureALot counters and flags
5814 // Note: the values are reset only when an actual
5815 // evacuation failure occurs.
5816 NOT_PRODUCT(reset_evacuation_should_fail();)
5817 }
5818
5819 // Enqueue any remaining references remaining on the STW
5820 // reference processor's discovered lists. We need to do
5821 // this after the card table is cleaned (and verified) as
5822 // the act of enqueueing entries on to the pending list
5823 // will log these updates (and dirty their associated
5824 // cards). We need these updates logged to update any
5825 // RSets.
5826 enqueue_discovered_references();
5827
5828 redirty_logged_cards();
5829 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5830 }
5831
5832 void G1CollectedHeap::free_region(HeapRegion* hr,
5833 FreeRegionList* free_list,
5834 bool par,
5835 bool locked) {
5836 assert(!hr->is_free(), "the region should not be free");
5837 assert(!hr->is_empty(), "the region should not be empty");
5838 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5839 assert(free_list != NULL, "pre-condition");
5840
5841 if (G1VerifyBitmaps) {
5842 MemRegion mr(hr->bottom(), hr->end());
5843 concurrent_mark()->clearRangePrevBitmap(mr);
5844 }
5845
5846 // Clear the card counts for this region.
5847 // Note: we only need to do this if the region is not young
5848 // (since we don't refine cards in young regions).
5849 if (!hr->is_young()) {
5850 _cg1r->hot_card_cache()->reset_card_counts(hr);
5851 }
5852 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5853 free_list->add_ordered(hr);
5854 }
5855
5856 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5857 FreeRegionList* free_list,
5858 bool par) {
5859 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5860 assert(free_list != NULL, "pre-condition");
5861
5862 size_t hr_capacity = hr->capacity();
5863 // We need to read this before we make the region non-humongous,
5864 // otherwise the information will be gone.
5865 uint last_index = hr->last_hc_index();
5866 hr->clear_humongous();
5867 free_region(hr, free_list, par);
5868
5869 uint i = hr->hrm_index() + 1;
5870 while (i < last_index) {
5871 HeapRegion* curr_hr = region_at(i);
5872 assert(curr_hr->is_continues_humongous(), "invariant");
5873 curr_hr->clear_humongous();
5874 free_region(curr_hr, free_list, par);
5875 i += 1;
5876 }
5877 }
5878
5879 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5880 const HeapRegionSetCount& humongous_regions_removed) {
5881 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5882 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5883 _old_set.bulk_remove(old_regions_removed);
5884 _humongous_set.bulk_remove(humongous_regions_removed);
5885 }
5886
5887 }
5888
5889 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5890 assert(list != NULL, "list can't be null");
5891 if (!list->is_empty()) {
5892 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5893 _hrm.insert_list_into_free_list(list);
5894 }
5895 }
5896
5897 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5898 decrease_used(bytes);
5899 }
5900
5901 class G1ParCleanupCTTask : public AbstractGangTask {
5902 G1SATBCardTableModRefBS* _ct_bs;
5903 G1CollectedHeap* _g1h;
5904 HeapRegion* volatile _su_head;
5905 public:
5906 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5907 G1CollectedHeap* g1h) :
5908 AbstractGangTask("G1 Par Cleanup CT Task"),
5909 _ct_bs(ct_bs), _g1h(g1h) { }
5910
5911 void work(uint worker_id) {
5912 HeapRegion* r;
5913 while (r = _g1h->pop_dirty_cards_region()) {
5914 clear_cards(r);
5915 }
5916 }
5917
5918 void clear_cards(HeapRegion* r) {
5919 // Cards of the survivors should have already been dirtied.
5920 if (!r->is_survivor()) {
5921 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5922 }
5923 }
5924 };
5925
5926 #ifndef PRODUCT
5927 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5928 G1CollectedHeap* _g1h;
5929 G1SATBCardTableModRefBS* _ct_bs;
5930 public:
5931 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5932 : _g1h(g1h), _ct_bs(ct_bs) { }
5933 virtual bool doHeapRegion(HeapRegion* r) {
5934 if (r->is_survivor()) {
5935 _g1h->verify_dirty_region(r);
5936 } else {
5937 _g1h->verify_not_dirty_region(r);
5938 }
5939 return false;
5940 }
5941 };
5942
5943 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5944 // All of the region should be clean.
5945 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5946 MemRegion mr(hr->bottom(), hr->end());
5947 ct_bs->verify_not_dirty_region(mr);
5948 }
5949
5950 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5951 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5952 // dirty allocated blocks as they allocate them. The thread that
5953 // retires each region and replaces it with a new one will do a
5954 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5955 // not dirty that area (one less thing to have to do while holding
5956 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5957 // is dirty.
5958 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5959 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5960 if (hr->is_young()) {
5961 ct_bs->verify_g1_young_region(mr);
5962 } else {
5963 ct_bs->verify_dirty_region(mr);
5964 }
5965 }
5966
5967 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5968 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5969 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5970 verify_dirty_region(hr);
5971 }
5972 }
5973
5974 void G1CollectedHeap::verify_dirty_young_regions() {
5975 verify_dirty_young_list(_young_list->first_region());
5976 }
5977
5978 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5979 HeapWord* tams, HeapWord* end) {
5980 guarantee(tams <= end,
5981 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5982 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5983 if (result < end) {
5984 gclog_or_tty->cr();
5985 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5986 bitmap_name, p2i(result));
5987 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5988 bitmap_name, p2i(tams), p2i(end));
5989 return false;
5990 }
5991 return true;
5992 }
5993
5994 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5995 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5996 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5997
5998 HeapWord* bottom = hr->bottom();
5999 HeapWord* ptams = hr->prev_top_at_mark_start();
6000 HeapWord* ntams = hr->next_top_at_mark_start();
6001 HeapWord* end = hr->end();
6002
6003 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6004
6005 bool res_n = true;
6006 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6007 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6008 // if we happen to be in that state.
6009 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
6010 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6011 }
6012 if (!res_p || !res_n) {
6013 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
6014 HR_FORMAT_PARAMS(hr));
6015 gclog_or_tty->print_cr("#### Caller: %s", caller);
6016 return false;
6017 }
6018 return true;
6019 }
6020
6021 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6022 if (!G1VerifyBitmaps) return;
6023
6024 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6025 }
6026
6027 class G1VerifyBitmapClosure : public HeapRegionClosure {
6028 private:
6029 const char* _caller;
6030 G1CollectedHeap* _g1h;
6031 bool _failures;
6032
6033 public:
6034 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6035 _caller(caller), _g1h(g1h), _failures(false) { }
6036
6037 bool failures() { return _failures; }
6038
6039 virtual bool doHeapRegion(HeapRegion* hr) {
6040 if (hr->is_continues_humongous()) return false;
6041
6042 bool result = _g1h->verify_bitmaps(_caller, hr);
6043 if (!result) {
6044 _failures = true;
6045 }
6046 return false;
6047 }
6048 };
6049
6050 void G1CollectedHeap::check_bitmaps(const char* caller) {
6051 if (!G1VerifyBitmaps) return;
6052
6053 G1VerifyBitmapClosure cl(caller, this);
6054 heap_region_iterate(&cl);
6055 guarantee(!cl.failures(), "bitmap verification");
6056 }
6057
6058 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
6059 private:
6060 bool _failures;
6061 public:
6062 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
6063
6064 virtual bool doHeapRegion(HeapRegion* hr) {
6065 uint i = hr->hrm_index();
6066 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
6067 if (hr->is_humongous()) {
6068 if (hr->in_collection_set()) {
6069 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
6070 _failures = true;
6071 return true;
6072 }
6073 if (cset_state.is_in_cset()) {
6074 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
6075 _failures = true;
6076 return true;
6077 }
6078 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
6079 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
6080 _failures = true;
6081 return true;
6082 }
6083 } else {
6084 if (cset_state.is_humongous()) {
6085 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6086 _failures = true;
6087 return true;
6088 }
6089 if (hr->in_collection_set() != cset_state.is_in_cset()) {
6090 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6091 hr->in_collection_set(), cset_state.value(), i);
6092 _failures = true;
6093 return true;
6094 }
6095 if (cset_state.is_in_cset()) {
6096 if (hr->is_young() != (cset_state.is_young())) {
6097 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6098 hr->is_young(), cset_state.value(), i);
6099 _failures = true;
6100 return true;
6101 }
6102 if (hr->is_old() != (cset_state.is_old())) {
6103 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6104 hr->is_old(), cset_state.value(), i);
6105 _failures = true;
6106 return true;
6107 }
6108 }
6109 }
6110 return false;
6111 }
6112
6113 bool failures() const { return _failures; }
6114 };
6115
6116 bool G1CollectedHeap::check_cset_fast_test() {
6117 G1CheckCSetFastTableClosure cl;
6118 _hrm.iterate(&cl);
6119 return !cl.failures();
6120 }
6121 #endif // PRODUCT
6122
6123 void G1CollectedHeap::cleanUpCardTable() {
6124 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6125 double start = os::elapsedTime();
6126
6127 {
6128 // Iterate over the dirty cards region list.
6129 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6130
6131 workers()->run_task(&cleanup_task);
6132 #ifndef PRODUCT
6133 if (G1VerifyCTCleanup || VerifyAfterGC) {
6134 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6135 heap_region_iterate(&cleanup_verifier);
6136 }
6137 #endif
6138 }
6139
6140 double elapsed = os::elapsedTime() - start;
6141 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6142 }
6143
6144 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6145 size_t pre_used = 0;
6146 FreeRegionList local_free_list("Local List for CSet Freeing");
6147
6148 double young_time_ms = 0.0;
6149 double non_young_time_ms = 0.0;
6150
6151 // Since the collection set is a superset of the the young list,
6152 // all we need to do to clear the young list is clear its
6153 // head and length, and unlink any young regions in the code below
6154 _young_list->clear();
6155
6156 G1CollectorPolicy* policy = g1_policy();
6157
6158 double start_sec = os::elapsedTime();
6159 bool non_young = true;
6160
6161 HeapRegion* cur = cs_head;
6162 int age_bound = -1;
6163 size_t rs_lengths = 0;
6164
6165 while (cur != NULL) {
6166 assert(!is_on_master_free_list(cur), "sanity");
6167 if (non_young) {
6168 if (cur->is_young()) {
6169 double end_sec = os::elapsedTime();
6170 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6171 non_young_time_ms += elapsed_ms;
6172
6173 start_sec = os::elapsedTime();
6174 non_young = false;
6175 }
6176 } else {
6177 if (!cur->is_young()) {
6178 double end_sec = os::elapsedTime();
6179 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6180 young_time_ms += elapsed_ms;
6181
6182 start_sec = os::elapsedTime();
6183 non_young = true;
6184 }
6185 }
6186
6187 rs_lengths += cur->rem_set()->occupied_locked();
6188
6189 HeapRegion* next = cur->next_in_collection_set();
6190 assert(cur->in_collection_set(), "bad CS");
6191 cur->set_next_in_collection_set(NULL);
6192 clear_in_cset(cur);
6193
6194 if (cur->is_young()) {
6195 int index = cur->young_index_in_cset();
6196 assert(index != -1, "invariant");
6197 assert((uint) index < policy->young_cset_region_length(), "invariant");
6198 size_t words_survived = _surviving_young_words[index];
6199 cur->record_surv_words_in_group(words_survived);
6200
6201 // At this point the we have 'popped' cur from the collection set
6202 // (linked via next_in_collection_set()) but it is still in the
6203 // young list (linked via next_young_region()). Clear the
6204 // _next_young_region field.
6205 cur->set_next_young_region(NULL);
6206 } else {
6207 int index = cur->young_index_in_cset();
6208 assert(index == -1, "invariant");
6209 }
6210
6211 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6212 (!cur->is_young() && cur->young_index_in_cset() == -1),
6213 "invariant" );
6214
6215 if (!cur->evacuation_failed()) {
6216 MemRegion used_mr = cur->used_region();
6217
6218 // And the region is empty.
6219 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6220 pre_used += cur->used();
6221 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6222 } else {
6223 cur->uninstall_surv_rate_group();
6224 if (cur->is_young()) {
6225 cur->set_young_index_in_cset(-1);
6226 }
6227 cur->set_evacuation_failed(false);
6228 // The region is now considered to be old.
6229 cur->set_old();
6230 _old_set.add(cur);
6231 evacuation_info.increment_collectionset_used_after(cur->used());
6232 }
6233 cur = next;
6234 }
6235
6236 evacuation_info.set_regions_freed(local_free_list.length());
6237 policy->record_max_rs_lengths(rs_lengths);
6238 policy->cset_regions_freed();
6239
6240 double end_sec = os::elapsedTime();
6241 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6242
6243 if (non_young) {
6244 non_young_time_ms += elapsed_ms;
6245 } else {
6246 young_time_ms += elapsed_ms;
6247 }
6248
6249 prepend_to_freelist(&local_free_list);
6250 decrement_summary_bytes(pre_used);
6251 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6252 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6253 }
6254
6255 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6256 private:
6257 FreeRegionList* _free_region_list;
6258 HeapRegionSet* _proxy_set;
6259 HeapRegionSetCount _humongous_regions_removed;
6260 size_t _freed_bytes;
6261 public:
6262
6263 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6264 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6265 }
6266
6267 virtual bool doHeapRegion(HeapRegion* r) {
6268 if (!r->is_starts_humongous()) {
6269 return false;
6270 }
6271
6272 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6273
6274 oop obj = (oop)r->bottom();
6275 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6276
6277 // The following checks whether the humongous object is live are sufficient.
6278 // The main additional check (in addition to having a reference from the roots
6279 // or the young gen) is whether the humongous object has a remembered set entry.
6280 //
6281 // A humongous object cannot be live if there is no remembered set for it
6282 // because:
6283 // - there can be no references from within humongous starts regions referencing
6284 // the object because we never allocate other objects into them.
6285 // (I.e. there are no intra-region references that may be missed by the
6286 // remembered set)
6287 // - as soon there is a remembered set entry to the humongous starts region
6288 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6289 // until the end of a concurrent mark.
6290 //
6291 // It is not required to check whether the object has been found dead by marking
6292 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6293 // all objects allocated during that time are considered live.
6294 // SATB marking is even more conservative than the remembered set.
6295 // So if at this point in the collection there is no remembered set entry,
6296 // nobody has a reference to it.
6297 // At the start of collection we flush all refinement logs, and remembered sets
6298 // are completely up-to-date wrt to references to the humongous object.
6299 //
6300 // Other implementation considerations:
6301 // - never consider object arrays at this time because they would pose
6302 // considerable effort for cleaning up the the remembered sets. This is
6303 // required because stale remembered sets might reference locations that
6304 // are currently allocated into.
6305 uint region_idx = r->hrm_index();
6306 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6307 !r->rem_set()->is_empty()) {
6308
6309 if (G1TraceEagerReclaimHumongousObjects) {
6310 gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
6311 region_idx,
6312 (size_t)obj->size() * HeapWordSize,
6313 p2i(r->bottom()),
6314 r->region_num(),
6315 r->rem_set()->occupied(),
6316 r->rem_set()->strong_code_roots_list_length(),
6317 next_bitmap->isMarked(r->bottom()),
6318 g1h->is_humongous_reclaim_candidate(region_idx),
6319 obj->is_typeArray()
6320 );
6321 }
6322
6323 return false;
6324 }
6325
6326 guarantee(obj->is_typeArray(),
6327 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6328 PTR_FORMAT " is not.",
6329 p2i(r->bottom())));
6330
6331 if (G1TraceEagerReclaimHumongousObjects) {
6332 gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
6333 region_idx,
6334 (size_t)obj->size() * HeapWordSize,
6335 p2i(r->bottom()),
6336 r->region_num(),
6337 r->rem_set()->occupied(),
6338 r->rem_set()->strong_code_roots_list_length(),
6339 next_bitmap->isMarked(r->bottom()),
6340 g1h->is_humongous_reclaim_candidate(region_idx),
6341 obj->is_typeArray()
6342 );
6343 }
6344 // Need to clear mark bit of the humongous object if already set.
6345 if (next_bitmap->isMarked(r->bottom())) {
6346 next_bitmap->clear(r->bottom());
6347 }
6348 _freed_bytes += r->used();
6349 r->set_containing_set(NULL);
6350 _humongous_regions_removed.increment(1u, r->capacity());
6351 g1h->free_humongous_region(r, _free_region_list, false);
6352
6353 return false;
6354 }
6355
6356 HeapRegionSetCount& humongous_free_count() {
6357 return _humongous_regions_removed;
6358 }
6359
6360 size_t bytes_freed() const {
6361 return _freed_bytes;
6362 }
6363
6364 size_t humongous_reclaimed() const {
6365 return _humongous_regions_removed.length();
6366 }
6367 };
6368
6369 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6370 assert_at_safepoint(true);
6371
6372 if (!G1EagerReclaimHumongousObjects ||
6373 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6374 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6375 return;
6376 }
6377
6378 double start_time = os::elapsedTime();
6379
6380 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6381
6382 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6383 heap_region_iterate(&cl);
6384
6385 HeapRegionSetCount empty_set;
6386 remove_from_old_sets(empty_set, cl.humongous_free_count());
6387
6388 G1HRPrinter* hrp = hr_printer();
6389 if (hrp->is_active()) {
6390 FreeRegionListIterator iter(&local_cleanup_list);
6391 while (iter.more_available()) {
6392 HeapRegion* hr = iter.get_next();
6393 hrp->cleanup(hr);
6394 }
6395 }
6396
6397 prepend_to_freelist(&local_cleanup_list);
6398 decrement_summary_bytes(cl.bytes_freed());
6399
6400 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6401 cl.humongous_reclaimed());
6402 }
6403
6404 // This routine is similar to the above but does not record
6405 // any policy statistics or update free lists; we are abandoning
6406 // the current incremental collection set in preparation of a
6407 // full collection. After the full GC we will start to build up
6408 // the incremental collection set again.
6409 // This is only called when we're doing a full collection
6410 // and is immediately followed by the tearing down of the young list.
6411
6412 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6413 HeapRegion* cur = cs_head;
6414
6415 while (cur != NULL) {
6416 HeapRegion* next = cur->next_in_collection_set();
6417 assert(cur->in_collection_set(), "bad CS");
6418 cur->set_next_in_collection_set(NULL);
6419 clear_in_cset(cur);
6420 cur->set_young_index_in_cset(-1);
6421 cur = next;
6422 }
6423 }
6424
6425 void G1CollectedHeap::set_free_regions_coming() {
6426 if (G1ConcRegionFreeingVerbose) {
6427 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6428 "setting free regions coming");
6429 }
6430
6431 assert(!free_regions_coming(), "pre-condition");
6432 _free_regions_coming = true;
6433 }
6434
6435 void G1CollectedHeap::reset_free_regions_coming() {
6436 assert(free_regions_coming(), "pre-condition");
6437
6438 {
6439 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6440 _free_regions_coming = false;
6441 SecondaryFreeList_lock->notify_all();
6442 }
6443
6444 if (G1ConcRegionFreeingVerbose) {
6445 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6446 "reset free regions coming");
6447 }
6448 }
6449
6450 void G1CollectedHeap::wait_while_free_regions_coming() {
6451 // Most of the time we won't have to wait, so let's do a quick test
6452 // first before we take the lock.
6453 if (!free_regions_coming()) {
6454 return;
6455 }
6456
6457 if (G1ConcRegionFreeingVerbose) {
6458 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6459 "waiting for free regions");
6460 }
6461
6462 {
6463 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6464 while (free_regions_coming()) {
6465 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6466 }
6467 }
6468
6469 if (G1ConcRegionFreeingVerbose) {
6470 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6471 "done waiting for free regions");
6472 }
6473 }
6474
6475 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6476 _young_list->push_region(hr);
6477 }
6478
6479 class NoYoungRegionsClosure: public HeapRegionClosure {
6480 private:
6481 bool _success;
6482 public:
6483 NoYoungRegionsClosure() : _success(true) { }
6484 bool doHeapRegion(HeapRegion* r) {
6485 if (r->is_young()) {
6486 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6487 p2i(r->bottom()), p2i(r->end()));
6488 _success = false;
6489 }
6490 return false;
6491 }
6492 bool success() { return _success; }
6493 };
6494
6495 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6496 bool ret = _young_list->check_list_empty(check_sample);
6497
6498 if (check_heap) {
6499 NoYoungRegionsClosure closure;
6500 heap_region_iterate(&closure);
6501 ret = ret && closure.success();
6502 }
6503
6504 return ret;
6505 }
6506
6507 class TearDownRegionSetsClosure : public HeapRegionClosure {
6508 private:
6509 HeapRegionSet *_old_set;
6510
6511 public:
6512 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6513
6514 bool doHeapRegion(HeapRegion* r) {
6515 if (r->is_old()) {
6516 _old_set->remove(r);
6517 } else {
6518 // We ignore free regions, we'll empty the free list afterwards.
6519 // We ignore young regions, we'll empty the young list afterwards.
6520 // We ignore humongous regions, we're not tearing down the
6521 // humongous regions set.
6522 assert(r->is_free() || r->is_young() || r->is_humongous(),
6523 "it cannot be another type");
6524 }
6525 return false;
6526 }
6527
6528 ~TearDownRegionSetsClosure() {
6529 assert(_old_set->is_empty(), "post-condition");
6530 }
6531 };
6532
6533 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6534 assert_at_safepoint(true /* should_be_vm_thread */);
6535
6536 if (!free_list_only) {
6537 TearDownRegionSetsClosure cl(&_old_set);
6538 heap_region_iterate(&cl);
6539
6540 // Note that emptying the _young_list is postponed and instead done as
6541 // the first step when rebuilding the regions sets again. The reason for
6542 // this is that during a full GC string deduplication needs to know if
6543 // a collected region was young or old when the full GC was initiated.
6544 }
6545 _hrm.remove_all_free_regions();
6546 }
6547
6548 void G1CollectedHeap::increase_used(size_t bytes) {
6549 _summary_bytes_used += bytes;
6550 }
6551
6552 void G1CollectedHeap::decrease_used(size_t bytes) {
6553 assert(_summary_bytes_used >= bytes,
6554 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6555 _summary_bytes_used, bytes));
6556 _summary_bytes_used -= bytes;
6557 }
6558
6559 void G1CollectedHeap::set_used(size_t bytes) {
6560 _summary_bytes_used = bytes;
6561 }
6562
6563 class RebuildRegionSetsClosure : public HeapRegionClosure {
6564 private:
6565 bool _free_list_only;
6566 HeapRegionSet* _old_set;
6567 HeapRegionManager* _hrm;
6568 size_t _total_used;
6569
6570 public:
6571 RebuildRegionSetsClosure(bool free_list_only,
6572 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6573 _free_list_only(free_list_only),
6574 _old_set(old_set), _hrm(hrm), _total_used(0) {
6575 assert(_hrm->num_free_regions() == 0, "pre-condition");
6576 if (!free_list_only) {
6577 assert(_old_set->is_empty(), "pre-condition");
6578 }
6579 }
6580
6581 bool doHeapRegion(HeapRegion* r) {
6582 if (r->is_continues_humongous()) {
6583 return false;
6584 }
6585
6586 if (r->is_empty()) {
6587 // Add free regions to the free list
6588 r->set_free();
6589 r->set_allocation_context(AllocationContext::system());
6590 _hrm->insert_into_free_list(r);
6591 } else if (!_free_list_only) {
6592 assert(!r->is_young(), "we should not come across young regions");
6593
6594 if (r->is_humongous()) {
6595 // We ignore humongous regions. We left the humongous set unchanged.
6596 } else {
6597 // Objects that were compacted would have ended up on regions
6598 // that were previously old or free. Archive regions (which are
6599 // old) will not have been touched.
6600 assert(r->is_free() || r->is_old(), "invariant");
6601 // We now consider them old, so register as such. Leave
6602 // archive regions set that way, however, while still adding
6603 // them to the old set.
6604 if (!r->is_archive()) {
6605 r->set_old();
6606 }
6607 _old_set->add(r);
6608 }
6609 _total_used += r->used();
6610 }
6611
6612 return false;
6613 }
6614
6615 size_t total_used() {
6616 return _total_used;
6617 }
6618 };
6619
6620 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6621 assert_at_safepoint(true /* should_be_vm_thread */);
6622
6623 if (!free_list_only) {
6624 _young_list->empty_list();
6625 }
6626
6627 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6628 heap_region_iterate(&cl);
6629
6630 if (!free_list_only) {
6631 set_used(cl.total_used());
6632 if (_archive_allocator != NULL) {
6633 _archive_allocator->clear_used();
6634 }
6635 }
6636 assert(used_unlocked() == recalculate_used(),
6637 err_msg("inconsistent used_unlocked(), "
6638 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6639 used_unlocked(), recalculate_used()));
6640 }
6641
6642 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6643 _refine_cte_cl_concurrency = concurrent;
6644 }
6645
6646 bool G1CollectedHeap::refine_cte_cl_concurrency() {
6647 return _refine_cte_cl_concurrency;
6648 }
6649
6650 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6651 HeapRegion* hr = heap_region_containing(p);
6652 return hr->is_in(p);
6653 }
6654
6655 // Methods for the mutator alloc region
6656
6657 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6658 bool force) {
6659 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6660 assert(!force || g1_policy()->can_expand_young_list(),
6661 "if force is true we should be able to expand the young list");
6662 bool young_list_full = g1_policy()->is_young_list_full();
6663 if (force || !young_list_full) {
6664 HeapRegion* new_alloc_region = new_region(word_size,
6665 false /* is_old */,
6666 false /* do_expand */);
6667 if (new_alloc_region != NULL) {
6668 set_region_short_lived_locked(new_alloc_region);
6669 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6670 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6671 return new_alloc_region;
6672 }
6673 }
6674 return NULL;
6675 }
6676
6677 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6678 size_t allocated_bytes) {
6679 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6680 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6681
6682 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6683 increase_used(allocated_bytes);
6684 _hr_printer.retire(alloc_region);
6685 // We update the eden sizes here, when the region is retired,
6686 // instead of when it's allocated, since this is the point that its
6687 // used space has been recored in _summary_bytes_used.
6688 g1mm()->update_eden_size();
6689 }
6690
6691 // Methods for the GC alloc regions
6692
6693 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6694 uint count,
6695 InCSetState dest) {
6696 assert(FreeList_lock->owned_by_self(), "pre-condition");
6697
6698 if (count < g1_policy()->max_regions(dest)) {
6699 const bool is_survivor = (dest.is_young());
6700 HeapRegion* new_alloc_region = new_region(word_size,
6701 !is_survivor,
6702 true /* do_expand */);
6703 if (new_alloc_region != NULL) {
6704 // We really only need to do this for old regions given that we
6705 // should never scan survivors. But it doesn't hurt to do it
6706 // for survivors too.
6707 new_alloc_region->record_timestamp();
6708 if (is_survivor) {
6709 new_alloc_region->set_survivor();
6710 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6711 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6712 } else {
6713 new_alloc_region->set_old();
6714 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6715 check_bitmaps("Old Region Allocation", new_alloc_region);
6716 }
6717 bool during_im = collector_state()->during_initial_mark_pause();
6718 new_alloc_region->note_start_of_copying(during_im);
6719 return new_alloc_region;
6720 }
6721 }
6722 return NULL;
6723 }
6724
6725 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6726 size_t allocated_bytes,
6727 InCSetState dest) {
6728 bool during_im = collector_state()->during_initial_mark_pause();
6729 alloc_region->note_end_of_copying(during_im);
6730 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6731 if (dest.is_young()) {
6732 young_list()->add_survivor_region(alloc_region);
6733 } else {
6734 _old_set.add(alloc_region);
6735 }
6736 _hr_printer.retire(alloc_region);
6737 }
6738
6739 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6740 bool expanded = false;
6741 uint index = _hrm.find_highest_free(&expanded);
6742
6743 if (index != G1_NO_HRM_INDEX) {
6744 if (expanded) {
6745 ergo_verbose1(ErgoHeapSizing,
6746 "attempt heap expansion",
6747 ergo_format_reason("requested address range outside heap bounds")
6748 ergo_format_byte("region size"),
6749 HeapRegion::GrainWords * HeapWordSize);
6750 }
6751 _hrm.allocate_free_regions_starting_at(index, 1);
6752 return region_at(index);
6753 }
6754 return NULL;
6755 }
6756
6757
6758 // Heap region set verification
6759
6760 class VerifyRegionListsClosure : public HeapRegionClosure {
6761 private:
6762 HeapRegionSet* _old_set;
6763 HeapRegionSet* _humongous_set;
6764 HeapRegionManager* _hrm;
6765
6766 public:
6767 HeapRegionSetCount _old_count;
6768 HeapRegionSetCount _humongous_count;
6769 HeapRegionSetCount _free_count;
6770
6771 VerifyRegionListsClosure(HeapRegionSet* old_set,
6772 HeapRegionSet* humongous_set,
6773 HeapRegionManager* hrm) :
6774 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6775 _old_count(), _humongous_count(), _free_count(){ }
6776
6777 bool doHeapRegion(HeapRegion* hr) {
6778 if (hr->is_continues_humongous()) {
6779 return false;
6780 }
6781
6782 if (hr->is_young()) {
6783 // TODO
6784 } else if (hr->is_starts_humongous()) {
6785 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6786 _humongous_count.increment(1u, hr->capacity());
6787 } else if (hr->is_empty()) {
6788 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6789 _free_count.increment(1u, hr->capacity());
6790 } else if (hr->is_old()) {
6791 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6792 _old_count.increment(1u, hr->capacity());
6793 } else {
6794 // There are no other valid region types. Check for one invalid
6795 // one we can identify: pinned without old or humongous set.
6796 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6797 ShouldNotReachHere();
6798 }
6799 return false;
6800 }
6801
6802 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6803 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6804 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6805 old_set->total_capacity_bytes(), _old_count.capacity()));
6806
6807 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6808 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6809 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6810
6811 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6812 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6813 free_list->total_capacity_bytes(), _free_count.capacity()));
6814 }
6815 };
6816
6817 void G1CollectedHeap::verify_region_sets() {
6818 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6819
6820 // First, check the explicit lists.
6821 _hrm.verify();
6822 {
6823 // Given that a concurrent operation might be adding regions to
6824 // the secondary free list we have to take the lock before
6825 // verifying it.
6826 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6827 _secondary_free_list.verify_list();
6828 }
6829
6830 // If a concurrent region freeing operation is in progress it will
6831 // be difficult to correctly attributed any free regions we come
6832 // across to the correct free list given that they might belong to
6833 // one of several (free_list, secondary_free_list, any local lists,
6834 // etc.). So, if that's the case we will skip the rest of the
6835 // verification operation. Alternatively, waiting for the concurrent
6836 // operation to complete will have a non-trivial effect on the GC's
6837 // operation (no concurrent operation will last longer than the
6838 // interval between two calls to verification) and it might hide
6839 // any issues that we would like to catch during testing.
6840 if (free_regions_coming()) {
6841 return;
6842 }
6843
6844 // Make sure we append the secondary_free_list on the free_list so
6845 // that all free regions we will come across can be safely
6846 // attributed to the free_list.
6847 append_secondary_free_list_if_not_empty_with_lock();
6848
6849 // Finally, make sure that the region accounting in the lists is
6850 // consistent with what we see in the heap.
6851
6852 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6853 heap_region_iterate(&cl);
6854 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6855 }
6856
6857 // Optimized nmethod scanning
6858
6859 class RegisterNMethodOopClosure: public OopClosure {
6860 G1CollectedHeap* _g1h;
6861 nmethod* _nm;
6862
6863 template <class T> void do_oop_work(T* p) {
6864 T heap_oop = oopDesc::load_heap_oop(p);
6865 if (!oopDesc::is_null(heap_oop)) {
6866 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6867 HeapRegion* hr = _g1h->heap_region_containing(obj);
6868 assert(!hr->is_continues_humongous(),
6869 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6870 " starting at " HR_FORMAT,
6871 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6872
6873 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6874 hr->add_strong_code_root_locked(_nm);
6875 }
6876 }
6877
6878 public:
6879 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6880 _g1h(g1h), _nm(nm) {}
6881
6882 void do_oop(oop* p) { do_oop_work(p); }
6883 void do_oop(narrowOop* p) { do_oop_work(p); }
6884 };
6885
6886 class UnregisterNMethodOopClosure: public OopClosure {
6887 G1CollectedHeap* _g1h;
6888 nmethod* _nm;
6889
6890 template <class T> void do_oop_work(T* p) {
6891 T heap_oop = oopDesc::load_heap_oop(p);
6892 if (!oopDesc::is_null(heap_oop)) {
6893 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6894 HeapRegion* hr = _g1h->heap_region_containing(obj);
6895 assert(!hr->is_continues_humongous(),
6896 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6897 " starting at " HR_FORMAT,
6898 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6899
6900 hr->remove_strong_code_root(_nm);
6901 }
6902 }
6903
6904 public:
6905 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6906 _g1h(g1h), _nm(nm) {}
6907
6908 void do_oop(oop* p) { do_oop_work(p); }
6909 void do_oop(narrowOop* p) { do_oop_work(p); }
6910 };
6911
6912 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6913 CollectedHeap::register_nmethod(nm);
6914
6915 guarantee(nm != NULL, "sanity");
6916 RegisterNMethodOopClosure reg_cl(this, nm);
6917 nm->oops_do(®_cl);
6918 }
6919
6920 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6921 CollectedHeap::unregister_nmethod(nm);
6922
6923 guarantee(nm != NULL, "sanity");
6924 UnregisterNMethodOopClosure reg_cl(this, nm);
6925 nm->oops_do(®_cl, true);
6926 }
6927
6928 void G1CollectedHeap::purge_code_root_memory() {
6929 double purge_start = os::elapsedTime();
6930 G1CodeRootSet::purge();
6931 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6932 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6933 }
6934
6935 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6936 G1CollectedHeap* _g1h;
6937
6938 public:
6939 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6940 _g1h(g1h) {}
6941
6942 void do_code_blob(CodeBlob* cb) {
6943 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6944 if (nm == NULL) {
6945 return;
6946 }
6947
6948 if (ScavengeRootsInCode) {
6949 _g1h->register_nmethod(nm);
6950 }
6951 }
6952 };
6953
6954 void G1CollectedHeap::rebuild_strong_code_roots() {
6955 RebuildStrongCodeRootClosure blob_cl(this);
6956 CodeCache::blobs_do(&blob_cl);
6957 }