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 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "oops/oop.pcgc.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74
75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
76
77 // turn it on so that the contents of the young list (scan-only /
78 // to-be-collected) are printed at "strategic" points before / during
79 // / after the collection --- this is useful for debugging
80 #define YOUNG_LIST_VERBOSE 0
81 // CURRENT STATUS
82 // This file is under construction. Search for "FIXME".
83
84 // INVARIANTS/NOTES
85 //
86 // All allocation activity covered by the G1CollectedHeap interface is
87 // serialized by acquiring the HeapLock. This happens in mem_allocate
88 // and allocate_new_tlab, which are the "entry" points to the
89 // allocation code from the rest of the JVM. (Note that this does not
90 // apply to TLAB allocation, which is not part of this interface: it
91 // is done by clients of this interface.)
92
93 // Local to this file.
94
95 class RefineCardTableEntryClosure: public CardTableEntryClosure {
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure() : _concurrent(true) { }
99
100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
102 // This path is executed by the concurrent refine or mutator threads,
103 // concurrently, and so we do not care if card_ptr contains references
104 // that point into the collection set.
105 assert(!oops_into_cset, "should be");
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
120 private:
121 size_t _num_processed;
122
123 public:
124 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
125
126 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 _num_processed++;
129 return true;
130 }
131
132 size_t num_processed() const { return _num_processed; }
133 };
134
135 YoungList::YoungList(G1CollectedHeap* g1h) :
136 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
138 guarantee(check_list_empty(false), "just making sure...");
139 }
140
141 void YoungList::push_region(HeapRegion *hr) {
142 assert(!hr->is_young(), "should not already be young");
143 assert(hr->get_next_young_region() == NULL, "cause it should!");
144
145 hr->set_next_young_region(_head);
146 _head = hr;
147
148 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
149 ++_length;
150 }
151
152 void YoungList::add_survivor_region(HeapRegion* hr) {
153 assert(hr->is_survivor(), "should be flagged as survivor region");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_survivor_head);
157 if (_survivor_head == NULL) {
158 _survivor_tail = hr;
159 }
160 _survivor_head = hr;
161 ++_survivor_length;
162 }
163
164 void YoungList::empty_list(HeapRegion* list) {
165 while (list != NULL) {
166 HeapRegion* next = list->get_next_young_region();
167 list->set_next_young_region(NULL);
168 list->uninstall_surv_rate_group();
169 // This is called before a Full GC and all the non-empty /
170 // non-humongous regions at the end of the Full GC will end up as
171 // old anyway.
172 list->set_old();
173 list = next;
174 }
175 }
176
177 void YoungList::empty_list() {
178 assert(check_list_well_formed(), "young list should be well formed");
179
180 empty_list(_head);
181 _head = NULL;
182 _length = 0;
183
184 empty_list(_survivor_head);
185 _survivor_head = NULL;
186 _survivor_tail = NULL;
187 _survivor_length = 0;
188
189 _last_sampled_rs_lengths = 0;
190
191 assert(check_list_empty(false), "just making sure...");
192 }
193
194 bool YoungList::check_list_well_formed() {
195 bool ret = true;
196
197 uint length = 0;
198 HeapRegion* curr = _head;
199 HeapRegion* last = NULL;
200 while (curr != NULL) {
201 if (!curr->is_young()) {
202 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
203 "incorrectly tagged (y: %d, surv: %d)",
204 curr->bottom(), curr->end(),
205 curr->is_young(), curr->is_survivor());
206 ret = false;
207 }
208 ++length;
209 last = curr;
210 curr = curr->get_next_young_region();
211 }
212 ret = ret && (length == _length);
213
214 if (!ret) {
215 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
216 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
217 length, _length);
218 }
219
220 return ret;
221 }
222
223 bool YoungList::check_list_empty(bool check_sample) {
224 bool ret = true;
225
226 if (_length != 0) {
227 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
228 _length);
229 ret = false;
230 }
231 if (check_sample && _last_sampled_rs_lengths != 0) {
232 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
233 ret = false;
234 }
235 if (_head != NULL) {
236 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
237 ret = false;
238 }
239 if (!ret) {
240 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
241 }
242
243 return ret;
244 }
245
246 void
247 YoungList::rs_length_sampling_init() {
248 _sampled_rs_lengths = 0;
249 _curr = _head;
250 }
251
252 bool
253 YoungList::rs_length_sampling_more() {
254 return _curr != NULL;
255 }
256
257 void
258 YoungList::rs_length_sampling_next() {
259 assert( _curr != NULL, "invariant" );
260 size_t rs_length = _curr->rem_set()->occupied();
261
262 _sampled_rs_lengths += rs_length;
263
264 // The current region may not yet have been added to the
265 // incremental collection set (it gets added when it is
266 // retired as the current allocation region).
267 if (_curr->in_collection_set()) {
268 // Update the collection set policy information for this region
269 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
270 }
271
272 _curr = _curr->get_next_young_region();
273 if (_curr == NULL) {
274 _last_sampled_rs_lengths = _sampled_rs_lengths;
275 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
276 }
277 }
278
279 void
280 YoungList::reset_auxilary_lists() {
281 guarantee( is_empty(), "young list should be empty" );
282 assert(check_list_well_formed(), "young list should be well formed");
283
284 // Add survivor regions to SurvRateGroup.
285 _g1h->g1_policy()->note_start_adding_survivor_regions();
286 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
287
288 int young_index_in_cset = 0;
289 for (HeapRegion* curr = _survivor_head;
290 curr != NULL;
291 curr = curr->get_next_young_region()) {
292 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
293
294 // The region is a non-empty survivor so let's add it to
295 // the incremental collection set for the next evacuation
296 // pause.
297 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
298 young_index_in_cset += 1;
299 }
300 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
301 _g1h->g1_policy()->note_stop_adding_survivor_regions();
302
303 _head = _survivor_head;
304 _length = _survivor_length;
305 if (_survivor_head != NULL) {
306 assert(_survivor_tail != NULL, "cause it shouldn't be");
307 assert(_survivor_length > 0, "invariant");
308 _survivor_tail->set_next_young_region(NULL);
309 }
310
311 // Don't clear the survivor list handles until the start of
312 // the next evacuation pause - we need it in order to re-tag
313 // the survivor regions from this evacuation pause as 'young'
314 // at the start of the next.
315
316 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
317
318 assert(check_list_well_formed(), "young list should be well formed");
319 }
320
321 void YoungList::print() {
322 HeapRegion* lists[] = {_head, _survivor_head};
323 const char* names[] = {"YOUNG", "SURVIVOR"};
324
325 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
326 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
327 HeapRegion *curr = lists[list];
328 if (curr == NULL)
329 gclog_or_tty->print_cr(" empty");
330 while (curr != NULL) {
331 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
332 HR_FORMAT_PARAMS(curr),
333 curr->prev_top_at_mark_start(),
334 curr->next_top_at_mark_start(),
335 curr->age_in_surv_rate_group_cond());
336 curr = curr->get_next_young_region();
337 }
338 }
339
340 gclog_or_tty->cr();
341 }
342
343 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
344 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
345 }
346
347 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
348 // The from card cache is not the memory that is actually committed. So we cannot
349 // take advantage of the zero_filled parameter.
350 reset_from_card_cache(start_idx, num_regions);
351 }
352
353 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
354 {
355 // Claim the right to put the region on the dirty cards region list
356 // by installing a self pointer.
357 HeapRegion* next = hr->get_next_dirty_cards_region();
358 if (next == NULL) {
359 HeapRegion* res = (HeapRegion*)
360 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
361 NULL);
362 if (res == NULL) {
363 HeapRegion* head;
364 do {
365 // Put the region to the dirty cards region list.
366 head = _dirty_cards_region_list;
367 next = (HeapRegion*)
368 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
369 if (next == head) {
370 assert(hr->get_next_dirty_cards_region() == hr,
371 "hr->get_next_dirty_cards_region() != hr");
372 if (next == NULL) {
373 // The last region in the list points to itself.
374 hr->set_next_dirty_cards_region(hr);
375 } else {
376 hr->set_next_dirty_cards_region(next);
377 }
378 }
379 } while (next != head);
380 }
381 }
382 }
383
384 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
385 {
386 HeapRegion* head;
387 HeapRegion* hr;
388 do {
389 head = _dirty_cards_region_list;
390 if (head == NULL) {
391 return NULL;
392 }
393 HeapRegion* new_head = head->get_next_dirty_cards_region();
394 if (head == new_head) {
395 // The last region.
396 new_head = NULL;
397 }
398 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
399 head);
400 } while (hr != head);
401 assert(hr != NULL, "invariant");
402 hr->set_next_dirty_cards_region(NULL);
403 return hr;
404 }
405
406 #ifdef ASSERT
407 // A region is added to the collection set as it is retired
408 // so an address p can point to a region which will be in the
409 // collection set but has not yet been retired. This method
410 // therefore is only accurate during a GC pause after all
411 // regions have been retired. It is used for debugging
412 // to check if an nmethod has references to objects that can
413 // be move during a partial collection. Though it can be
414 // inaccurate, it is sufficient for G1 because the conservative
415 // implementation of is_scavengable() for G1 will indicate that
416 // all nmethods must be scanned during a partial collection.
417 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
418 if (p == NULL) {
419 return false;
420 }
421 return heap_region_containing(p)->in_collection_set();
422 }
423 #endif
424
425 // Returns true if the reference points to an object that
426 // can move in an incremental collection.
427 bool G1CollectedHeap::is_scavengable(const void* p) {
428 HeapRegion* hr = heap_region_containing(p);
429 return !hr->is_humongous();
430 }
431
432 // Private class members.
433
434 G1CollectedHeap* G1CollectedHeap::_g1h;
435
436 // Private methods.
437
438 HeapRegion*
439 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
440 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
441 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
442 if (!_secondary_free_list.is_empty()) {
443 if (G1ConcRegionFreeingVerbose) {
444 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
445 "secondary_free_list has %u entries",
446 _secondary_free_list.length());
447 }
448 // It looks as if there are free regions available on the
449 // secondary_free_list. Let's move them to the free_list and try
450 // again to allocate from it.
451 append_secondary_free_list();
452
453 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
454 "empty we should have moved at least one entry to the free_list");
455 HeapRegion* res = _hrm.allocate_free_region(is_old);
456 if (G1ConcRegionFreeingVerbose) {
457 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
458 "allocated "HR_FORMAT" from secondary_free_list",
459 HR_FORMAT_PARAMS(res));
460 }
461 return res;
462 }
463
464 // Wait here until we get notified either when (a) there are no
465 // more free regions coming or (b) some regions have been moved on
466 // the secondary_free_list.
467 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
468 }
469
470 if (G1ConcRegionFreeingVerbose) {
471 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
472 "could not allocate from secondary_free_list");
473 }
474 return NULL;
475 }
476
477 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
478 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
479 "the only time we use this to allocate a humongous region is "
480 "when we are allocating a single humongous region");
481
482 HeapRegion* res;
483 if (G1StressConcRegionFreeing) {
484 if (!_secondary_free_list.is_empty()) {
485 if (G1ConcRegionFreeingVerbose) {
486 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
487 "forced to look at the secondary_free_list");
488 }
489 res = new_region_try_secondary_free_list(is_old);
490 if (res != NULL) {
491 return res;
492 }
493 }
494 }
495
496 res = _hrm.allocate_free_region(is_old);
497
498 if (res == NULL) {
499 if (G1ConcRegionFreeingVerbose) {
500 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
501 "res == NULL, trying the secondary_free_list");
502 }
503 res = new_region_try_secondary_free_list(is_old);
504 }
505 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
506 // Currently, only attempts to allocate GC alloc regions set
507 // do_expand to true. So, we should only reach here during a
508 // safepoint. If this assumption changes we might have to
509 // reconsider the use of _expand_heap_after_alloc_failure.
510 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
511
512 ergo_verbose1(ErgoHeapSizing,
513 "attempt heap expansion",
514 ergo_format_reason("region allocation request failed")
515 ergo_format_byte("allocation request"),
516 word_size * HeapWordSize);
517 if (expand(word_size * HeapWordSize)) {
518 // Given that expand() succeeded in expanding the heap, and we
519 // always expand the heap by an amount aligned to the heap
520 // region size, the free list should in theory not be empty.
521 // In either case allocate_free_region() will check for NULL.
522 res = _hrm.allocate_free_region(is_old);
523 } else {
524 _expand_heap_after_alloc_failure = false;
525 }
526 }
527 return res;
528 }
529
530 HeapWord*
531 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
532 uint num_regions,
533 size_t word_size,
534 AllocationContext_t context) {
535 assert(first != G1_NO_HRM_INDEX, "pre-condition");
536 assert(is_humongous(word_size), "word_size should be humongous");
537 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
538
539 // Index of last region in the series + 1.
540 uint last = first + num_regions;
541
542 // We need to initialize the region(s) we just discovered. This is
543 // a bit tricky given that it can happen concurrently with
544 // refinement threads refining cards on these regions and
545 // potentially wanting to refine the BOT as they are scanning
546 // those cards (this can happen shortly after a cleanup; see CR
547 // 6991377). So we have to set up the region(s) carefully and in
548 // a specific order.
549
550 // The word size sum of all the regions we will allocate.
551 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
552 assert(word_size <= word_size_sum, "sanity");
553
554 // This will be the "starts humongous" region.
555 HeapRegion* first_hr = region_at(first);
556 // The header of the new object will be placed at the bottom of
557 // the first region.
558 HeapWord* new_obj = first_hr->bottom();
559 // This will be the new end of the first region in the series that
560 // should also match the end of the last region in the series.
561 HeapWord* new_end = new_obj + word_size_sum;
562 // This will be the new top of the first region that will reflect
563 // this allocation.
564 HeapWord* new_top = new_obj + word_size;
565
566 // First, we need to zero the header of the space that we will be
567 // allocating. When we update top further down, some refinement
568 // threads might try to scan the region. By zeroing the header we
569 // ensure that any thread that will try to scan the region will
570 // come across the zero klass word and bail out.
571 //
572 // NOTE: It would not have been correct to have used
573 // CollectedHeap::fill_with_object() and make the space look like
574 // an int array. The thread that is doing the allocation will
575 // later update the object header to a potentially different array
576 // type and, for a very short period of time, the klass and length
577 // fields will be inconsistent. This could cause a refinement
578 // thread to calculate the object size incorrectly.
579 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
580
581 // We will set up the first region as "starts humongous". This
582 // will also update the BOT covering all the regions to reflect
583 // that there is a single object that starts at the bottom of the
584 // first region.
585 first_hr->set_starts_humongous(new_top, new_end);
586 first_hr->set_allocation_context(context);
587 // Then, if there are any, we will set up the "continues
588 // humongous" regions.
589 HeapRegion* hr = NULL;
590 for (uint i = first + 1; i < last; ++i) {
591 hr = region_at(i);
592 hr->set_continues_humongous(first_hr);
593 hr->set_allocation_context(context);
594 }
595 // If we have "continues humongous" regions (hr != NULL), then the
596 // end of the last one should match new_end.
597 assert(hr == NULL || hr->end() == new_end, "sanity");
598
599 // Up to this point no concurrent thread would have been able to
600 // do any scanning on any region in this series. All the top
601 // fields still point to bottom, so the intersection between
602 // [bottom,top] and [card_start,card_end] will be empty. Before we
603 // update the top fields, we'll do a storestore to make sure that
604 // no thread sees the update to top before the zeroing of the
605 // object header and the BOT initialization.
606 OrderAccess::storestore();
607
608 // Now that the BOT and the object header have been initialized,
609 // we can update top of the "starts humongous" region.
610 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
611 "new_top should be in this region");
612 first_hr->set_top(new_top);
613 if (_hr_printer.is_active()) {
614 HeapWord* bottom = first_hr->bottom();
615 HeapWord* end = first_hr->orig_end();
616 if ((first + 1) == last) {
617 // the series has a single humongous region
618 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
619 } else {
620 // the series has more than one humongous regions
621 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
622 }
623 }
624
625 // Now, we will update the top fields of the "continues humongous"
626 // regions. The reason we need to do this is that, otherwise,
627 // these regions would look empty and this will confuse parts of
628 // G1. For example, the code that looks for a consecutive number
629 // of empty regions will consider them empty and try to
630 // re-allocate them. We can extend is_empty() to also include
631 // !is_continues_humongous(), but it is easier to just update the top
632 // fields here. The way we set top for all regions (i.e., top ==
633 // end for all regions but the last one, top == new_top for the
634 // last one) is actually used when we will free up the humongous
635 // region in free_humongous_region().
636 hr = NULL;
637 for (uint i = first + 1; i < last; ++i) {
638 hr = region_at(i);
639 if ((i + 1) == last) {
640 // last continues humongous region
641 assert(hr->bottom() < new_top && new_top <= hr->end(),
642 "new_top should fall on this region");
643 hr->set_top(new_top);
644 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
645 } else {
646 // not last one
647 assert(new_top > hr->end(), "new_top should be above this region");
648 hr->set_top(hr->end());
649 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
650 }
651 }
652 // If we have continues humongous regions (hr != NULL), then the
653 // end of the last one should match new_end and its top should
654 // match new_top.
655 assert(hr == NULL ||
656 (hr->end() == new_end && hr->top() == new_top), "sanity");
657 check_bitmaps("Humongous Region Allocation", first_hr);
658
659 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
660 _allocator->increase_used(first_hr->used());
661 _humongous_set.add(first_hr);
662
663 return new_obj;
664 }
665
666 // If could fit into free regions w/o expansion, try.
667 // Otherwise, if can expand, do so.
668 // Otherwise, if using ex regions might help, try with ex given back.
669 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
670 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
671
672 verify_region_sets_optional();
673
674 uint first = G1_NO_HRM_INDEX;
675 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
676
677 if (obj_regions == 1) {
678 // Only one region to allocate, try to use a fast path by directly allocating
679 // from the free lists. Do not try to expand here, we will potentially do that
680 // later.
681 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
682 if (hr != NULL) {
683 first = hr->hrm_index();
684 }
685 } else {
686 // We can't allocate humongous regions spanning more than one region while
687 // cleanupComplete() is running, since some of the regions we find to be
688 // empty might not yet be added to the free list. It is not straightforward
689 // to know in which list they are on so that we can remove them. We only
690 // need to do this if we need to allocate more than one region to satisfy the
691 // current humongous allocation request. If we are only allocating one region
692 // we use the one-region region allocation code (see above), that already
693 // potentially waits for regions from the secondary free list.
694 wait_while_free_regions_coming();
695 append_secondary_free_list_if_not_empty_with_lock();
696
697 // Policy: Try only empty regions (i.e. already committed first). Maybe we
698 // are lucky enough to find some.
699 first = _hrm.find_contiguous_only_empty(obj_regions);
700 if (first != G1_NO_HRM_INDEX) {
701 _hrm.allocate_free_regions_starting_at(first, obj_regions);
702 }
703 }
704
705 if (first == G1_NO_HRM_INDEX) {
706 // Policy: We could not find enough regions for the humongous object in the
707 // free list. Look through the heap to find a mix of free and uncommitted regions.
708 // If so, try expansion.
709 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
710 if (first != G1_NO_HRM_INDEX) {
711 // We found something. Make sure these regions are committed, i.e. expand
712 // the heap. Alternatively we could do a defragmentation GC.
713 ergo_verbose1(ErgoHeapSizing,
714 "attempt heap expansion",
715 ergo_format_reason("humongous allocation request failed")
716 ergo_format_byte("allocation request"),
717 word_size * HeapWordSize);
718
719 _hrm.expand_at(first, obj_regions);
720 g1_policy()->record_new_heap_size(num_regions());
721
722 #ifdef ASSERT
723 for (uint i = first; i < first + obj_regions; ++i) {
724 HeapRegion* hr = region_at(i);
725 assert(hr->is_free(), "sanity");
726 assert(hr->is_empty(), "sanity");
727 assert(is_on_master_free_list(hr), "sanity");
728 }
729 #endif
730 _hrm.allocate_free_regions_starting_at(first, obj_regions);
731 } else {
732 // Policy: Potentially trigger a defragmentation GC.
733 }
734 }
735
736 HeapWord* result = NULL;
737 if (first != G1_NO_HRM_INDEX) {
738 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
739 word_size, context);
740 assert(result != NULL, "it should always return a valid result");
741
742 // A successful humongous object allocation changes the used space
743 // information of the old generation so we need to recalculate the
744 // sizes and update the jstat counters here.
745 g1mm()->update_sizes();
746 }
747
748 verify_region_sets_optional();
749
750 return result;
751 }
752
753 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
754 assert_heap_not_locked_and_not_at_safepoint();
755 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
756
757 uint dummy_gc_count_before;
758 uint dummy_gclocker_retry_count = 0;
759 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
760 }
761
762 HeapWord*
763 G1CollectedHeap::mem_allocate(size_t word_size,
764 bool* gc_overhead_limit_was_exceeded) {
765 assert_heap_not_locked_and_not_at_safepoint();
766
767 // Loop until the allocation is satisfied, or unsatisfied after GC.
768 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
769 uint gc_count_before;
770
771 HeapWord* result = NULL;
772 if (!is_humongous(word_size)) {
773 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
774 } else {
775 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
776 }
777 if (result != NULL) {
778 return result;
779 }
780
781 // Create the garbage collection operation...
782 VM_G1CollectForAllocation op(gc_count_before, word_size);
783 op.set_allocation_context(AllocationContext::current());
784
785 // ...and get the VM thread to execute it.
786 VMThread::execute(&op);
787
788 if (op.prologue_succeeded() && op.pause_succeeded()) {
789 // If the operation was successful we'll return the result even
790 // if it is NULL. If the allocation attempt failed immediately
791 // after a Full GC, it's unlikely we'll be able to allocate now.
792 HeapWord* result = op.result();
793 if (result != NULL && !is_humongous(word_size)) {
794 // Allocations that take place on VM operations do not do any
795 // card dirtying and we have to do it here. We only have to do
796 // this for non-humongous allocations, though.
797 dirty_young_block(result, word_size);
798 }
799 return result;
800 } else {
801 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
802 return NULL;
803 }
804 assert(op.result() == NULL,
805 "the result should be NULL if the VM op did not succeed");
806 }
807
808 // Give a warning if we seem to be looping forever.
809 if ((QueuedAllocationWarningCount > 0) &&
810 (try_count % QueuedAllocationWarningCount == 0)) {
811 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
812 }
813 }
814
815 ShouldNotReachHere();
816 return NULL;
817 }
818
819 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
820 AllocationContext_t context,
821 uint* gc_count_before_ret,
822 uint* gclocker_retry_count_ret) {
823 // Make sure you read the note in attempt_allocation_humongous().
824
825 assert_heap_not_locked_and_not_at_safepoint();
826 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
827 "be called for humongous allocation requests");
828
829 // We should only get here after the first-level allocation attempt
830 // (attempt_allocation()) failed to allocate.
831
832 // We will loop until a) we manage to successfully perform the
833 // allocation or b) we successfully schedule a collection which
834 // fails to perform the allocation. b) is the only case when we'll
835 // return NULL.
836 HeapWord* result = NULL;
837 for (int try_count = 1; /* we'll return */; try_count += 1) {
838 bool should_try_gc;
839 uint gc_count_before;
840
841 {
842 MutexLockerEx x(Heap_lock);
843 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
844 false /* bot_updates */);
845 if (result != NULL) {
846 return result;
847 }
848
849 // If we reach here, attempt_allocation_locked() above failed to
850 // allocate a new region. So the mutator alloc region should be NULL.
851 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
852
853 if (GC_locker::is_active_and_needs_gc()) {
854 if (g1_policy()->can_expand_young_list()) {
855 // No need for an ergo verbose message here,
856 // can_expand_young_list() does this when it returns true.
857 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
858 false /* bot_updates */);
859 if (result != NULL) {
860 return result;
861 }
862 }
863 should_try_gc = false;
864 } else {
865 // The GCLocker may not be active but the GCLocker initiated
866 // GC may not yet have been performed (GCLocker::needs_gc()
867 // returns true). In this case we do not try this GC and
868 // wait until the GCLocker initiated GC is performed, and
869 // then retry the allocation.
870 if (GC_locker::needs_gc()) {
871 should_try_gc = false;
872 } else {
873 // Read the GC count while still holding the Heap_lock.
874 gc_count_before = total_collections();
875 should_try_gc = true;
876 }
877 }
878 }
879
880 if (should_try_gc) {
881 bool succeeded;
882 result = do_collection_pause(word_size, gc_count_before, &succeeded,
883 GCCause::_g1_inc_collection_pause);
884 if (result != NULL) {
885 assert(succeeded, "only way to get back a non-NULL result");
886 return result;
887 }
888
889 if (succeeded) {
890 // If we get here we successfully scheduled a collection which
891 // failed to allocate. No point in trying to allocate
892 // further. We'll just return NULL.
893 MutexLockerEx x(Heap_lock);
894 *gc_count_before_ret = total_collections();
895 return NULL;
896 }
897 } else {
898 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
899 MutexLockerEx x(Heap_lock);
900 *gc_count_before_ret = total_collections();
901 return NULL;
902 }
903 // The GCLocker is either active or the GCLocker initiated
904 // GC has not yet been performed. Stall until it is and
905 // then retry the allocation.
906 GC_locker::stall_until_clear();
907 (*gclocker_retry_count_ret) += 1;
908 }
909
910 // We can reach here if we were unsuccessful in scheduling a
911 // collection (because another thread beat us to it) or if we were
912 // stalled due to the GC locker. In either can we should retry the
913 // allocation attempt in case another thread successfully
914 // performed a collection and reclaimed enough space. We do the
915 // first attempt (without holding the Heap_lock) here and the
916 // follow-on attempt will be at the start of the next loop
917 // iteration (after taking the Heap_lock).
918 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
919 false /* bot_updates */);
920 if (result != NULL) {
921 return result;
922 }
923
924 // Give a warning if we seem to be looping forever.
925 if ((QueuedAllocationWarningCount > 0) &&
926 (try_count % QueuedAllocationWarningCount == 0)) {
927 warning("G1CollectedHeap::attempt_allocation_slow() "
928 "retries %d times", try_count);
929 }
930 }
931
932 ShouldNotReachHere();
933 return NULL;
934 }
935
936 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
937 uint* gc_count_before_ret,
938 uint* gclocker_retry_count_ret) {
939 // The structure of this method has a lot of similarities to
940 // attempt_allocation_slow(). The reason these two were not merged
941 // into a single one is that such a method would require several "if
942 // allocation is not humongous do this, otherwise do that"
943 // conditional paths which would obscure its flow. In fact, an early
944 // version of this code did use a unified method which was harder to
945 // follow and, as a result, it had subtle bugs that were hard to
946 // track down. So keeping these two methods separate allows each to
947 // be more readable. It will be good to keep these two in sync as
948 // much as possible.
949
950 assert_heap_not_locked_and_not_at_safepoint();
951 assert(is_humongous(word_size), "attempt_allocation_humongous() "
952 "should only be called for humongous allocations");
953
954 // Humongous objects can exhaust the heap quickly, so we should check if we
955 // need to start a marking cycle at each humongous object allocation. We do
956 // the check before we do the actual allocation. The reason for doing it
957 // before the allocation is that we avoid having to keep track of the newly
958 // allocated memory while we do a GC.
959 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
960 word_size)) {
961 collect(GCCause::_g1_humongous_allocation);
962 }
963
964 // We will loop until a) we manage to successfully perform the
965 // allocation or b) we successfully schedule a collection which
966 // fails to perform the allocation. b) is the only case when we'll
967 // return NULL.
968 HeapWord* result = NULL;
969 for (int try_count = 1; /* we'll return */; try_count += 1) {
970 bool should_try_gc;
971 uint gc_count_before;
972
973 {
974 MutexLockerEx x(Heap_lock);
975
976 // Given that humongous objects are not allocated in young
977 // regions, we'll first try to do the allocation without doing a
978 // collection hoping that there's enough space in the heap.
979 result = humongous_obj_allocate(word_size, AllocationContext::current());
980 if (result != NULL) {
981 return result;
982 }
983
984 if (GC_locker::is_active_and_needs_gc()) {
985 should_try_gc = false;
986 } else {
987 // The GCLocker may not be active but the GCLocker initiated
988 // GC may not yet have been performed (GCLocker::needs_gc()
989 // returns true). In this case we do not try this GC and
990 // wait until the GCLocker initiated GC is performed, and
991 // then retry the allocation.
992 if (GC_locker::needs_gc()) {
993 should_try_gc = false;
994 } else {
995 // Read the GC count while still holding the Heap_lock.
996 gc_count_before = total_collections();
997 should_try_gc = true;
998 }
999 }
1000 }
1001
1002 if (should_try_gc) {
1003 // If we failed to allocate the humongous object, we should try to
1004 // do a collection pause (if we're allowed) in case it reclaims
1005 // enough space for the allocation to succeed after the pause.
1006
1007 bool succeeded;
1008 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1009 GCCause::_g1_humongous_allocation);
1010 if (result != NULL) {
1011 assert(succeeded, "only way to get back a non-NULL result");
1012 return result;
1013 }
1014
1015 if (succeeded) {
1016 // If we get here we successfully scheduled a collection which
1017 // failed to allocate. No point in trying to allocate
1018 // further. We'll just return NULL.
1019 MutexLockerEx x(Heap_lock);
1020 *gc_count_before_ret = total_collections();
1021 return NULL;
1022 }
1023 } else {
1024 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1025 MutexLockerEx x(Heap_lock);
1026 *gc_count_before_ret = total_collections();
1027 return NULL;
1028 }
1029 // The GCLocker is either active or the GCLocker initiated
1030 // GC has not yet been performed. Stall until it is and
1031 // then retry the allocation.
1032 GC_locker::stall_until_clear();
1033 (*gclocker_retry_count_ret) += 1;
1034 }
1035
1036 // We can reach here if we were unsuccessful in scheduling a
1037 // collection (because another thread beat us to it) or if we were
1038 // stalled due to the GC locker. In either can we should retry the
1039 // allocation attempt in case another thread successfully
1040 // performed a collection and reclaimed enough space. Give a
1041 // warning if we seem to be looping forever.
1042
1043 if ((QueuedAllocationWarningCount > 0) &&
1044 (try_count % QueuedAllocationWarningCount == 0)) {
1045 warning("G1CollectedHeap::attempt_allocation_humongous() "
1046 "retries %d times", try_count);
1047 }
1048 }
1049
1050 ShouldNotReachHere();
1051 return NULL;
1052 }
1053
1054 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1055 AllocationContext_t context,
1056 bool expect_null_mutator_alloc_region) {
1057 assert_at_safepoint(true /* should_be_vm_thread */);
1058 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1059 !expect_null_mutator_alloc_region,
1060 "the current alloc region was unexpectedly found to be non-NULL");
1061
1062 if (!is_humongous(word_size)) {
1063 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1064 false /* bot_updates */);
1065 } else {
1066 HeapWord* result = humongous_obj_allocate(word_size, context);
1067 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1068 g1_policy()->set_initiate_conc_mark_if_possible();
1069 }
1070 return result;
1071 }
1072
1073 ShouldNotReachHere();
1074 }
1075
1076 class PostMCRemSetClearClosure: public HeapRegionClosure {
1077 G1CollectedHeap* _g1h;
1078 ModRefBarrierSet* _mr_bs;
1079 public:
1080 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1081 _g1h(g1h), _mr_bs(mr_bs) {}
1082
1083 bool doHeapRegion(HeapRegion* r) {
1084 HeapRegionRemSet* hrrs = r->rem_set();
1085
1086 if (r->is_continues_humongous()) {
1087 // We'll assert that the strong code root list and RSet is empty
1088 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1089 assert(hrrs->occupied() == 0, "RSet should be empty");
1090 return false;
1091 }
1092
1093 _g1h->reset_gc_time_stamps(r);
1094 hrrs->clear();
1095 // You might think here that we could clear just the cards
1096 // corresponding to the used region. But no: if we leave a dirty card
1097 // in a region we might allocate into, then it would prevent that card
1098 // from being enqueued, and cause it to be missed.
1099 // Re: the performance cost: we shouldn't be doing full GC anyway!
1100 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1101
1102 return false;
1103 }
1104 };
1105
1106 void G1CollectedHeap::clear_rsets_post_compaction() {
1107 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1108 heap_region_iterate(&rs_clear);
1109 }
1110
1111 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1112 G1CollectedHeap* _g1h;
1113 UpdateRSOopClosure _cl;
1114 int _worker_i;
1115 public:
1116 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1117 _cl(g1->g1_rem_set(), worker_i),
1118 _worker_i(worker_i),
1119 _g1h(g1)
1120 { }
1121
1122 bool doHeapRegion(HeapRegion* r) {
1123 if (!r->is_continues_humongous()) {
1124 _cl.set_from(r);
1125 r->oop_iterate(&_cl);
1126 }
1127 return false;
1128 }
1129 };
1130
1131 class ParRebuildRSTask: public AbstractGangTask {
1132 G1CollectedHeap* _g1;
1133 HeapRegionClaimer _hrclaimer;
1134
1135 public:
1136 ParRebuildRSTask(G1CollectedHeap* g1) :
1137 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1138
1139 void work(uint worker_id) {
1140 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1141 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1142 }
1143 };
1144
1145 class PostCompactionPrinterClosure: public HeapRegionClosure {
1146 private:
1147 G1HRPrinter* _hr_printer;
1148 public:
1149 bool doHeapRegion(HeapRegion* hr) {
1150 assert(!hr->is_young(), "not expecting to find young regions");
1151 if (hr->is_free()) {
1152 // We only generate output for non-empty regions.
1153 } else if (hr->is_starts_humongous()) {
1154 if (hr->region_num() == 1) {
1155 // single humongous region
1156 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1157 } else {
1158 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1159 }
1160 } else if (hr->is_continues_humongous()) {
1161 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1162 } else if (hr->is_old()) {
1163 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1164 } else {
1165 ShouldNotReachHere();
1166 }
1167 return false;
1168 }
1169
1170 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1171 : _hr_printer(hr_printer) { }
1172 };
1173
1174 void G1CollectedHeap::print_hrm_post_compaction() {
1175 PostCompactionPrinterClosure cl(hr_printer());
1176 heap_region_iterate(&cl);
1177 }
1178
1179 bool G1CollectedHeap::do_collection(bool explicit_gc,
1180 bool clear_all_soft_refs,
1181 size_t word_size) {
1182 assert_at_safepoint(true /* should_be_vm_thread */);
1183
1184 if (GC_locker::check_active_before_gc()) {
1185 return false;
1186 }
1187
1188 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1189 gc_timer->register_gc_start();
1190
1191 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1192 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1193
1194 SvcGCMarker sgcm(SvcGCMarker::FULL);
1195 ResourceMark rm;
1196
1197 print_heap_before_gc();
1198 trace_heap_before_gc(gc_tracer);
1199
1200 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1201
1202 verify_region_sets_optional();
1203
1204 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1205 collector_policy()->should_clear_all_soft_refs();
1206
1207 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1208
1209 {
1210 IsGCActiveMark x;
1211
1212 // Timing
1213 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1214 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1215
1216 {
1217 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1218 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1219 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1220
1221 g1_policy()->record_full_collection_start();
1222
1223 // Note: When we have a more flexible GC logging framework that
1224 // allows us to add optional attributes to a GC log record we
1225 // could consider timing and reporting how long we wait in the
1226 // following two methods.
1227 wait_while_free_regions_coming();
1228 // If we start the compaction before the CM threads finish
1229 // scanning the root regions we might trip them over as we'll
1230 // be moving objects / updating references. So let's wait until
1231 // they are done. By telling them to abort, they should complete
1232 // early.
1233 _cm->root_regions()->abort();
1234 _cm->root_regions()->wait_until_scan_finished();
1235 append_secondary_free_list_if_not_empty_with_lock();
1236
1237 gc_prologue(true);
1238 increment_total_collections(true /* full gc */);
1239 increment_old_marking_cycles_started();
1240
1241 assert(used() == recalculate_used(), "Should be equal");
1242
1243 verify_before_gc();
1244
1245 check_bitmaps("Full GC Start");
1246 pre_full_gc_dump(gc_timer);
1247
1248 COMPILER2_PRESENT(DerivedPointerTable::clear());
1249
1250 // Disable discovery and empty the discovered lists
1251 // for the CM ref processor.
1252 ref_processor_cm()->disable_discovery();
1253 ref_processor_cm()->abandon_partial_discovery();
1254 ref_processor_cm()->verify_no_references_recorded();
1255
1256 // Abandon current iterations of concurrent marking and concurrent
1257 // refinement, if any are in progress. We have to do this before
1258 // wait_until_scan_finished() below.
1259 concurrent_mark()->abort();
1260
1261 // Make sure we'll choose a new allocation region afterwards.
1262 _allocator->release_mutator_alloc_region();
1263 _allocator->abandon_gc_alloc_regions();
1264 g1_rem_set()->cleanupHRRS();
1265
1266 // We should call this after we retire any currently active alloc
1267 // regions so that all the ALLOC / RETIRE events are generated
1268 // before the start GC event.
1269 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1270
1271 // We may have added regions to the current incremental collection
1272 // set between the last GC or pause and now. We need to clear the
1273 // incremental collection set and then start rebuilding it afresh
1274 // after this full GC.
1275 abandon_collection_set(g1_policy()->inc_cset_head());
1276 g1_policy()->clear_incremental_cset();
1277 g1_policy()->stop_incremental_cset_building();
1278
1279 tear_down_region_sets(false /* free_list_only */);
1280 g1_policy()->set_gcs_are_young(true);
1281
1282 // See the comments in g1CollectedHeap.hpp and
1283 // G1CollectedHeap::ref_processing_init() about
1284 // how reference processing currently works in G1.
1285
1286 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1287 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1288
1289 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1290 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1291
1292 ref_processor_stw()->enable_discovery();
1293 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1294
1295 // Do collection work
1296 {
1297 HandleMark hm; // Discard invalid handles created during gc
1298 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1299 }
1300
1301 assert(num_free_regions() == 0, "we should not have added any free regions");
1302 rebuild_region_sets(false /* free_list_only */);
1303
1304 // Enqueue any discovered reference objects that have
1305 // not been removed from the discovered lists.
1306 ref_processor_stw()->enqueue_discovered_references();
1307
1308 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1309
1310 MemoryService::track_memory_usage();
1311
1312 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1313 ref_processor_stw()->verify_no_references_recorded();
1314
1315 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1316 ClassLoaderDataGraph::purge();
1317 MetaspaceAux::verify_metrics();
1318
1319 // Note: since we've just done a full GC, concurrent
1320 // marking is no longer active. Therefore we need not
1321 // re-enable reference discovery for the CM ref processor.
1322 // That will be done at the start of the next marking cycle.
1323 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1324 ref_processor_cm()->verify_no_references_recorded();
1325
1326 reset_gc_time_stamp();
1327 // Since everything potentially moved, we will clear all remembered
1328 // sets, and clear all cards. Later we will rebuild remembered
1329 // sets. We will also reset the GC time stamps of the regions.
1330 clear_rsets_post_compaction();
1331 check_gc_time_stamps();
1332
1333 // Resize the heap if necessary.
1334 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1335
1336 if (_hr_printer.is_active()) {
1337 // We should do this after we potentially resize the heap so
1338 // that all the COMMIT / UNCOMMIT events are generated before
1339 // the end GC event.
1340
1341 print_hrm_post_compaction();
1342 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1343 }
1344
1345 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1346 if (hot_card_cache->use_cache()) {
1347 hot_card_cache->reset_card_counts();
1348 hot_card_cache->reset_hot_cache();
1349 }
1350
1351 // Rebuild remembered sets of all regions.
1352 uint n_workers =
1353 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1354 workers()->active_workers(),
1355 Threads::number_of_non_daemon_threads());
1356 assert(UseDynamicNumberOfGCThreads ||
1357 n_workers == workers()->total_workers(),
1358 "If not dynamic should be using all the workers");
1359 workers()->set_active_workers(n_workers);
1360 // Set parallel threads in the heap (_n_par_threads) only
1361 // before a parallel phase and always reset it to 0 after
1362 // the phase so that the number of parallel threads does
1363 // no get carried forward to a serial phase where there
1364 // may be code that is "possibly_parallel".
1365 set_par_threads(n_workers);
1366
1367 ParRebuildRSTask rebuild_rs_task(this);
1368 assert(UseDynamicNumberOfGCThreads ||
1369 workers()->active_workers() == workers()->total_workers(),
1370 "Unless dynamic should use total workers");
1371 // Use the most recent number of active workers
1372 assert(workers()->active_workers() > 0,
1373 "Active workers not properly set");
1374 set_par_threads(workers()->active_workers());
1375 workers()->run_task(&rebuild_rs_task);
1376 set_par_threads(0);
1377
1378 // Rebuild the strong code root lists for each region
1379 rebuild_strong_code_roots();
1380
1381 if (true) { // FIXME
1382 MetaspaceGC::compute_new_size();
1383 }
1384
1385 #ifdef TRACESPINNING
1386 ParallelTaskTerminator::print_termination_counts();
1387 #endif
1388
1389 // Discard all rset updates
1390 JavaThread::dirty_card_queue_set().abandon_logs();
1391 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1392
1393 _young_list->reset_sampled_info();
1394 // At this point there should be no regions in the
1395 // entire heap tagged as young.
1396 assert(check_young_list_empty(true /* check_heap */),
1397 "young list should be empty at this point");
1398
1399 // Update the number of full collections that have been completed.
1400 increment_old_marking_cycles_completed(false /* concurrent */);
1401
1402 _hrm.verify_optional();
1403 verify_region_sets_optional();
1404
1405 verify_after_gc();
1406
1407 // Clear the previous marking bitmap, if needed for bitmap verification.
1408 // Note we cannot do this when we clear the next marking bitmap in
1409 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1410 // objects marked during a full GC against the previous bitmap.
1411 // But we need to clear it before calling check_bitmaps below since
1412 // the full GC has compacted objects and updated TAMS but not updated
1413 // the prev bitmap.
1414 if (G1VerifyBitmaps) {
1415 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1416 }
1417 check_bitmaps("Full GC End");
1418
1419 // Start a new incremental collection set for the next pause
1420 assert(g1_policy()->collection_set() == NULL, "must be");
1421 g1_policy()->start_incremental_cset_building();
1422
1423 clear_cset_fast_test();
1424
1425 _allocator->init_mutator_alloc_region();
1426
1427 g1_policy()->record_full_collection_end();
1428
1429 if (G1Log::fine()) {
1430 g1_policy()->print_heap_transition();
1431 }
1432
1433 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1434 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1435 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1436 // before any GC notifications are raised.
1437 g1mm()->update_sizes();
1438
1439 gc_epilogue(true);
1440 }
1441
1442 if (G1Log::finer()) {
1443 g1_policy()->print_detailed_heap_transition(true /* full */);
1444 }
1445
1446 print_heap_after_gc();
1447 trace_heap_after_gc(gc_tracer);
1448
1449 post_full_gc_dump(gc_timer);
1450
1451 gc_timer->register_gc_end();
1452 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1453 }
1454
1455 return true;
1456 }
1457
1458 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1459 // do_collection() will return whether it succeeded in performing
1460 // the GC. Currently, there is no facility on the
1461 // do_full_collection() API to notify the caller than the collection
1462 // did not succeed (e.g., because it was locked out by the GC
1463 // locker). So, right now, we'll ignore the return value.
1464 bool dummy = do_collection(true, /* explicit_gc */
1465 clear_all_soft_refs,
1466 0 /* word_size */);
1467 }
1468
1469 // This code is mostly copied from TenuredGeneration.
1470 void
1471 G1CollectedHeap::
1472 resize_if_necessary_after_full_collection(size_t word_size) {
1473 // Include the current allocation, if any, and bytes that will be
1474 // pre-allocated to support collections, as "used".
1475 const size_t used_after_gc = used();
1476 const size_t capacity_after_gc = capacity();
1477 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1478
1479 // This is enforced in arguments.cpp.
1480 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1481 "otherwise the code below doesn't make sense");
1482
1483 // We don't have floating point command-line arguments
1484 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1485 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1486 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1487 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1488
1489 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1490 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1491
1492 // We have to be careful here as these two calculations can overflow
1493 // 32-bit size_t's.
1494 double used_after_gc_d = (double) used_after_gc;
1495 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1496 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1497
1498 // Let's make sure that they are both under the max heap size, which
1499 // by default will make them fit into a size_t.
1500 double desired_capacity_upper_bound = (double) max_heap_size;
1501 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1502 desired_capacity_upper_bound);
1503 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1504 desired_capacity_upper_bound);
1505
1506 // We can now safely turn them into size_t's.
1507 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1508 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1509
1510 // This assert only makes sense here, before we adjust them
1511 // with respect to the min and max heap size.
1512 assert(minimum_desired_capacity <= maximum_desired_capacity,
1513 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1514 "maximum_desired_capacity = "SIZE_FORMAT,
1515 minimum_desired_capacity, maximum_desired_capacity));
1516
1517 // Should not be greater than the heap max size. No need to adjust
1518 // it with respect to the heap min size as it's a lower bound (i.e.,
1519 // we'll try to make the capacity larger than it, not smaller).
1520 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1521 // Should not be less than the heap min size. No need to adjust it
1522 // with respect to the heap max size as it's an upper bound (i.e.,
1523 // we'll try to make the capacity smaller than it, not greater).
1524 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1525
1526 if (capacity_after_gc < minimum_desired_capacity) {
1527 // Don't expand unless it's significant
1528 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1529 ergo_verbose4(ErgoHeapSizing,
1530 "attempt heap expansion",
1531 ergo_format_reason("capacity lower than "
1532 "min desired capacity after Full GC")
1533 ergo_format_byte("capacity")
1534 ergo_format_byte("occupancy")
1535 ergo_format_byte_perc("min desired capacity"),
1536 capacity_after_gc, used_after_gc,
1537 minimum_desired_capacity, (double) MinHeapFreeRatio);
1538 expand(expand_bytes);
1539
1540 // No expansion, now see if we want to shrink
1541 } else if (capacity_after_gc > maximum_desired_capacity) {
1542 // Capacity too large, compute shrinking size
1543 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1544 ergo_verbose4(ErgoHeapSizing,
1545 "attempt heap shrinking",
1546 ergo_format_reason("capacity higher than "
1547 "max desired capacity after Full GC")
1548 ergo_format_byte("capacity")
1549 ergo_format_byte("occupancy")
1550 ergo_format_byte_perc("max desired capacity"),
1551 capacity_after_gc, used_after_gc,
1552 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1553 shrink(shrink_bytes);
1554 }
1555 }
1556
1557
1558 HeapWord*
1559 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1560 AllocationContext_t context,
1561 bool* succeeded) {
1562 assert_at_safepoint(true /* should_be_vm_thread */);
1563
1564 *succeeded = true;
1565 // Let's attempt the allocation first.
1566 HeapWord* result =
1567 attempt_allocation_at_safepoint(word_size,
1568 context,
1569 false /* expect_null_mutator_alloc_region */);
1570 if (result != NULL) {
1571 assert(*succeeded, "sanity");
1572 return result;
1573 }
1574
1575 // In a G1 heap, we're supposed to keep allocation from failing by
1576 // incremental pauses. Therefore, at least for now, we'll favor
1577 // expansion over collection. (This might change in the future if we can
1578 // do something smarter than full collection to satisfy a failed alloc.)
1579 result = expand_and_allocate(word_size, context);
1580 if (result != NULL) {
1581 assert(*succeeded, "sanity");
1582 return result;
1583 }
1584
1585 // Expansion didn't work, we'll try to do a Full GC.
1586 bool gc_succeeded = do_collection(false, /* explicit_gc */
1587 false, /* clear_all_soft_refs */
1588 word_size);
1589 if (!gc_succeeded) {
1590 *succeeded = false;
1591 return NULL;
1592 }
1593
1594 // Retry the allocation
1595 result = attempt_allocation_at_safepoint(word_size,
1596 context,
1597 true /* expect_null_mutator_alloc_region */);
1598 if (result != NULL) {
1599 assert(*succeeded, "sanity");
1600 return result;
1601 }
1602
1603 // Then, try a Full GC that will collect all soft references.
1604 gc_succeeded = do_collection(false, /* explicit_gc */
1605 true, /* clear_all_soft_refs */
1606 word_size);
1607 if (!gc_succeeded) {
1608 *succeeded = false;
1609 return NULL;
1610 }
1611
1612 // Retry the allocation once more
1613 result = attempt_allocation_at_safepoint(word_size,
1614 context,
1615 true /* expect_null_mutator_alloc_region */);
1616 if (result != NULL) {
1617 assert(*succeeded, "sanity");
1618 return result;
1619 }
1620
1621 assert(!collector_policy()->should_clear_all_soft_refs(),
1622 "Flag should have been handled and cleared prior to this point");
1623
1624 // What else? We might try synchronous finalization later. If the total
1625 // space available is large enough for the allocation, then a more
1626 // complete compaction phase than we've tried so far might be
1627 // appropriate.
1628 assert(*succeeded, "sanity");
1629 return NULL;
1630 }
1631
1632 // Attempting to expand the heap sufficiently
1633 // to support an allocation of the given "word_size". If
1634 // successful, perform the allocation and return the address of the
1635 // allocated block, or else "NULL".
1636
1637 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1638 assert_at_safepoint(true /* should_be_vm_thread */);
1639
1640 verify_region_sets_optional();
1641
1642 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1643 ergo_verbose1(ErgoHeapSizing,
1644 "attempt heap expansion",
1645 ergo_format_reason("allocation request failed")
1646 ergo_format_byte("allocation request"),
1647 word_size * HeapWordSize);
1648 if (expand(expand_bytes)) {
1649 _hrm.verify_optional();
1650 verify_region_sets_optional();
1651 return attempt_allocation_at_safepoint(word_size,
1652 context,
1653 false /* expect_null_mutator_alloc_region */);
1654 }
1655 return NULL;
1656 }
1657
1658 bool G1CollectedHeap::expand(size_t expand_bytes) {
1659 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1660 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1661 HeapRegion::GrainBytes);
1662 ergo_verbose2(ErgoHeapSizing,
1663 "expand the heap",
1664 ergo_format_byte("requested expansion amount")
1665 ergo_format_byte("attempted expansion amount"),
1666 expand_bytes, aligned_expand_bytes);
1667
1668 if (is_maximal_no_gc()) {
1669 ergo_verbose0(ErgoHeapSizing,
1670 "did not expand the heap",
1671 ergo_format_reason("heap already fully expanded"));
1672 return false;
1673 }
1674
1675 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1676 assert(regions_to_expand > 0, "Must expand by at least one region");
1677
1678 uint expanded_by = _hrm.expand_by(regions_to_expand);
1679
1680 if (expanded_by > 0) {
1681 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1682 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1683 g1_policy()->record_new_heap_size(num_regions());
1684 } else {
1685 ergo_verbose0(ErgoHeapSizing,
1686 "did not expand the heap",
1687 ergo_format_reason("heap expansion operation failed"));
1688 // The expansion of the virtual storage space was unsuccessful.
1689 // Let's see if it was because we ran out of swap.
1690 if (G1ExitOnExpansionFailure &&
1691 _hrm.available() >= regions_to_expand) {
1692 // We had head room...
1693 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1694 }
1695 }
1696 return regions_to_expand > 0;
1697 }
1698
1699 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1700 size_t aligned_shrink_bytes =
1701 ReservedSpace::page_align_size_down(shrink_bytes);
1702 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1703 HeapRegion::GrainBytes);
1704 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1705
1706 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1707 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1708
1709 ergo_verbose3(ErgoHeapSizing,
1710 "shrink the heap",
1711 ergo_format_byte("requested shrinking amount")
1712 ergo_format_byte("aligned shrinking amount")
1713 ergo_format_byte("attempted shrinking amount"),
1714 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1715 if (num_regions_removed > 0) {
1716 g1_policy()->record_new_heap_size(num_regions());
1717 } else {
1718 ergo_verbose0(ErgoHeapSizing,
1719 "did not shrink the heap",
1720 ergo_format_reason("heap shrinking operation failed"));
1721 }
1722 }
1723
1724 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1725 verify_region_sets_optional();
1726
1727 // We should only reach here at the end of a Full GC which means we
1728 // should not not be holding to any GC alloc regions. The method
1729 // below will make sure of that and do any remaining clean up.
1730 _allocator->abandon_gc_alloc_regions();
1731
1732 // Instead of tearing down / rebuilding the free lists here, we
1733 // could instead use the remove_all_pending() method on free_list to
1734 // remove only the ones that we need to remove.
1735 tear_down_region_sets(true /* free_list_only */);
1736 shrink_helper(shrink_bytes);
1737 rebuild_region_sets(true /* free_list_only */);
1738
1739 _hrm.verify_optional();
1740 verify_region_sets_optional();
1741 }
1742
1743 // Public methods.
1744
1745 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1746 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1747 #endif // _MSC_VER
1748
1749
1750 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1751 SharedHeap(policy_),
1752 _g1_policy(policy_),
1753 _dirty_card_queue_set(false),
1754 _into_cset_dirty_card_queue_set(false),
1755 _is_alive_closure_cm(this),
1756 _is_alive_closure_stw(this),
1757 _ref_processor_cm(NULL),
1758 _ref_processor_stw(NULL),
1759 _bot_shared(NULL),
1760 _evac_failure_scan_stack(NULL),
1761 _mark_in_progress(false),
1762 _cg1r(NULL),
1763 _g1mm(NULL),
1764 _refine_cte_cl(NULL),
1765 _full_collection(false),
1766 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1767 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1768 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1769 _humongous_is_live(),
1770 _has_humongous_reclaim_candidates(false),
1771 _free_regions_coming(false),
1772 _young_list(new YoungList(this)),
1773 _gc_time_stamp(0),
1774 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1775 _old_plab_stats(OldPLABSize, PLABWeight),
1776 _expand_heap_after_alloc_failure(true),
1777 _surviving_young_words(NULL),
1778 _old_marking_cycles_started(0),
1779 _old_marking_cycles_completed(0),
1780 _concurrent_cycle_started(false),
1781 _heap_summary_sent(false),
1782 _in_cset_fast_test(),
1783 _dirty_cards_region_list(NULL),
1784 _worker_cset_start_region(NULL),
1785 _worker_cset_start_region_time_stamp(NULL),
1786 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1787 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1788 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1789 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1790
1791 _g1h = this;
1792
1793 _allocator = G1Allocator::create_allocator(_g1h);
1794 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1795
1796 int n_queues = MAX2((int)ParallelGCThreads, 1);
1797 _task_queues = new RefToScanQueueSet(n_queues);
1798
1799 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1800 assert(n_rem_sets > 0, "Invariant.");
1801
1802 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1803 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1804 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1805
1806 for (int i = 0; i < n_queues; i++) {
1807 RefToScanQueue* q = new RefToScanQueue();
1808 q->initialize();
1809 _task_queues->register_queue(i, q);
1810 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1811 }
1812 clear_cset_start_regions();
1813
1814 // Initialize the G1EvacuationFailureALot counters and flags.
1815 NOT_PRODUCT(reset_evacuation_should_fail();)
1816
1817 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1818 }
1819
1820 jint G1CollectedHeap::initialize() {
1821 CollectedHeap::pre_initialize();
1822 os::enable_vtime();
1823
1824 G1Log::init();
1825
1826 // Necessary to satisfy locking discipline assertions.
1827
1828 MutexLocker x(Heap_lock);
1829
1830 // We have to initialize the printer before committing the heap, as
1831 // it will be used then.
1832 _hr_printer.set_active(G1PrintHeapRegions);
1833
1834 // While there are no constraints in the GC code that HeapWordSize
1835 // be any particular value, there are multiple other areas in the
1836 // system which believe this to be true (e.g. oop->object_size in some
1837 // cases incorrectly returns the size in wordSize units rather than
1838 // HeapWordSize).
1839 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1840
1841 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1842 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1843 size_t heap_alignment = collector_policy()->heap_alignment();
1844
1845 // Ensure that the sizes are properly aligned.
1846 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1847 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1848 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1849
1850 _refine_cte_cl = new RefineCardTableEntryClosure();
1851
1852 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1853
1854 // Reserve the maximum.
1855
1856 // When compressed oops are enabled, the preferred heap base
1857 // is calculated by subtracting the requested size from the
1858 // 32Gb boundary and using the result as the base address for
1859 // heap reservation. If the requested size is not aligned to
1860 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1861 // into the ReservedHeapSpace constructor) then the actual
1862 // base of the reserved heap may end up differing from the
1863 // address that was requested (i.e. the preferred heap base).
1864 // If this happens then we could end up using a non-optimal
1865 // compressed oops mode.
1866
1867 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1868 heap_alignment);
1869
1870 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1871
1872 // Create the barrier set for the entire reserved region.
1873 G1SATBCardTableLoggingModRefBS* bs
1874 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1875 bs->initialize();
1876 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1877 set_barrier_set(bs);
1878
1879 // Also create a G1 rem set.
1880 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1881
1882 // Carve out the G1 part of the heap.
1883
1884 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1885 G1RegionToSpaceMapper* heap_storage =
1886 G1RegionToSpaceMapper::create_mapper(g1_rs,
1887 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1888 HeapRegion::GrainBytes,
1889 1,
1890 mtJavaHeap);
1891 heap_storage->set_mapping_changed_listener(&_listener);
1892
1893 // Reserve space for the block offset table. We do not support automatic uncommit
1894 // for the card table at this time. BOT only.
1895 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1896 G1RegionToSpaceMapper* bot_storage =
1897 G1RegionToSpaceMapper::create_mapper(bot_rs,
1898 os::vm_page_size(),
1899 HeapRegion::GrainBytes,
1900 G1BlockOffsetSharedArray::N_bytes,
1901 mtGC);
1902
1903 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1904 G1RegionToSpaceMapper* cardtable_storage =
1905 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1906 os::vm_page_size(),
1907 HeapRegion::GrainBytes,
1908 G1BlockOffsetSharedArray::N_bytes,
1909 mtGC);
1910
1911 // Reserve space for the card counts table.
1912 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1913 G1RegionToSpaceMapper* card_counts_storage =
1914 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1915 os::vm_page_size(),
1916 HeapRegion::GrainBytes,
1917 G1BlockOffsetSharedArray::N_bytes,
1918 mtGC);
1919
1920 // Reserve space for prev and next bitmap.
1921 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1922
1923 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1924 G1RegionToSpaceMapper* prev_bitmap_storage =
1925 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1926 os::vm_page_size(),
1927 HeapRegion::GrainBytes,
1928 CMBitMap::mark_distance(),
1929 mtGC);
1930
1931 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1932 G1RegionToSpaceMapper* next_bitmap_storage =
1933 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1934 os::vm_page_size(),
1935 HeapRegion::GrainBytes,
1936 CMBitMap::mark_distance(),
1937 mtGC);
1938
1939 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1940 g1_barrier_set()->initialize(cardtable_storage);
1941 // Do later initialization work for concurrent refinement.
1942 _cg1r->init(card_counts_storage);
1943
1944 // 6843694 - ensure that the maximum region index can fit
1945 // in the remembered set structures.
1946 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1947 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1948
1949 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1950 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1951 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1952 "too many cards per region");
1953
1954 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1955
1956 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1957
1958 _g1h = this;
1959
1960 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1961 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1962
1963 // Create the ConcurrentMark data structure and thread.
1964 // (Must do this late, so that "max_regions" is defined.)
1965 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1966 if (_cm == NULL || !_cm->completed_initialization()) {
1967 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1968 return JNI_ENOMEM;
1969 }
1970 _cmThread = _cm->cmThread();
1971
1972 // Initialize the from_card cache structure of HeapRegionRemSet.
1973 HeapRegionRemSet::init_heap(max_regions());
1974
1975 // Now expand into the initial heap size.
1976 if (!expand(init_byte_size)) {
1977 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1978 return JNI_ENOMEM;
1979 }
1980
1981 // Perform any initialization actions delegated to the policy.
1982 g1_policy()->init();
1983
1984 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1985 SATB_Q_FL_lock,
1986 G1SATBProcessCompletedThreshold,
1987 Shared_SATB_Q_lock);
1988
1989 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1990 DirtyCardQ_CBL_mon,
1991 DirtyCardQ_FL_lock,
1992 concurrent_g1_refine()->yellow_zone(),
1993 concurrent_g1_refine()->red_zone(),
1994 Shared_DirtyCardQ_lock);
1995
1996 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1997 DirtyCardQ_CBL_mon,
1998 DirtyCardQ_FL_lock,
1999 -1, // never trigger processing
2000 -1, // no limit on length
2001 Shared_DirtyCardQ_lock,
2002 &JavaThread::dirty_card_queue_set());
2003
2004 // Initialize the card queue set used to hold cards containing
2005 // references into the collection set.
2006 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2007 DirtyCardQ_CBL_mon,
2008 DirtyCardQ_FL_lock,
2009 -1, // never trigger processing
2010 -1, // no limit on length
2011 Shared_DirtyCardQ_lock,
2012 &JavaThread::dirty_card_queue_set());
2013
2014 // Here we allocate the dummy HeapRegion that is required by the
2015 // G1AllocRegion class.
2016 HeapRegion* dummy_region = _hrm.get_dummy_region();
2017
2018 // We'll re-use the same region whether the alloc region will
2019 // require BOT updates or not and, if it doesn't, then a non-young
2020 // region will complain that it cannot support allocations without
2021 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2022 dummy_region->set_eden();
2023 // Make sure it's full.
2024 dummy_region->set_top(dummy_region->end());
2025 G1AllocRegion::setup(this, dummy_region);
2026
2027 _allocator->init_mutator_alloc_region();
2028
2029 // Do create of the monitoring and management support so that
2030 // values in the heap have been properly initialized.
2031 _g1mm = new G1MonitoringSupport(this);
2032
2033 G1StringDedup::initialize();
2034
2035 return JNI_OK;
2036 }
2037
2038 void G1CollectedHeap::stop() {
2039 // Stop all concurrent threads. We do this to make sure these threads
2040 // do not continue to execute and access resources (e.g. gclog_or_tty)
2041 // that are destroyed during shutdown.
2042 _cg1r->stop();
2043 _cmThread->stop();
2044 if (G1StringDedup::is_enabled()) {
2045 G1StringDedup::stop();
2046 }
2047 }
2048
2049 void G1CollectedHeap::clear_humongous_is_live_table() {
2050 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2051 _humongous_is_live.clear();
2052 }
2053
2054 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2055 return HeapRegion::max_region_size();
2056 }
2057
2058 void G1CollectedHeap::ref_processing_init() {
2059 // Reference processing in G1 currently works as follows:
2060 //
2061 // * There are two reference processor instances. One is
2062 // used to record and process discovered references
2063 // during concurrent marking; the other is used to
2064 // record and process references during STW pauses
2065 // (both full and incremental).
2066 // * Both ref processors need to 'span' the entire heap as
2067 // the regions in the collection set may be dotted around.
2068 //
2069 // * For the concurrent marking ref processor:
2070 // * Reference discovery is enabled at initial marking.
2071 // * Reference discovery is disabled and the discovered
2072 // references processed etc during remarking.
2073 // * Reference discovery is MT (see below).
2074 // * Reference discovery requires a barrier (see below).
2075 // * Reference processing may or may not be MT
2076 // (depending on the value of ParallelRefProcEnabled
2077 // and ParallelGCThreads).
2078 // * A full GC disables reference discovery by the CM
2079 // ref processor and abandons any entries on it's
2080 // discovered lists.
2081 //
2082 // * For the STW processor:
2083 // * Non MT discovery is enabled at the start of a full GC.
2084 // * Processing and enqueueing during a full GC is non-MT.
2085 // * During a full GC, references are processed after marking.
2086 //
2087 // * Discovery (may or may not be MT) is enabled at the start
2088 // of an incremental evacuation pause.
2089 // * References are processed near the end of a STW evacuation pause.
2090 // * For both types of GC:
2091 // * Discovery is atomic - i.e. not concurrent.
2092 // * Reference discovery will not need a barrier.
2093
2094 SharedHeap::ref_processing_init();
2095 MemRegion mr = reserved_region();
2096
2097 // Concurrent Mark ref processor
2098 _ref_processor_cm =
2099 new ReferenceProcessor(mr, // span
2100 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2101 // mt processing
2102 (int) ParallelGCThreads,
2103 // degree of mt processing
2104 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2105 // mt discovery
2106 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2107 // degree of mt discovery
2108 false,
2109 // Reference discovery is not atomic
2110 &_is_alive_closure_cm);
2111 // is alive closure
2112 // (for efficiency/performance)
2113
2114 // STW ref processor
2115 _ref_processor_stw =
2116 new ReferenceProcessor(mr, // span
2117 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2118 // mt processing
2119 MAX2((int)ParallelGCThreads, 1),
2120 // degree of mt processing
2121 (ParallelGCThreads > 1),
2122 // mt discovery
2123 MAX2((int)ParallelGCThreads, 1),
2124 // degree of mt discovery
2125 true,
2126 // Reference discovery is atomic
2127 &_is_alive_closure_stw);
2128 // is alive closure
2129 // (for efficiency/performance)
2130 }
2131
2132 size_t G1CollectedHeap::capacity() const {
2133 return _hrm.length() * HeapRegion::GrainBytes;
2134 }
2135
2136 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2137 assert(!hr->is_continues_humongous(), "pre-condition");
2138 hr->reset_gc_time_stamp();
2139 if (hr->is_starts_humongous()) {
2140 uint first_index = hr->hrm_index() + 1;
2141 uint last_index = hr->last_hc_index();
2142 for (uint i = first_index; i < last_index; i += 1) {
2143 HeapRegion* chr = region_at(i);
2144 assert(chr->is_continues_humongous(), "sanity");
2145 chr->reset_gc_time_stamp();
2146 }
2147 }
2148 }
2149
2150 #ifndef PRODUCT
2151 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2152 private:
2153 unsigned _gc_time_stamp;
2154 bool _failures;
2155
2156 public:
2157 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2158 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2159
2160 virtual bool doHeapRegion(HeapRegion* hr) {
2161 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2162 if (_gc_time_stamp != region_gc_time_stamp) {
2163 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2164 "expected %d", HR_FORMAT_PARAMS(hr),
2165 region_gc_time_stamp, _gc_time_stamp);
2166 _failures = true;
2167 }
2168 return false;
2169 }
2170
2171 bool failures() { return _failures; }
2172 };
2173
2174 void G1CollectedHeap::check_gc_time_stamps() {
2175 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2176 heap_region_iterate(&cl);
2177 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2178 }
2179 #endif // PRODUCT
2180
2181 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2182 DirtyCardQueue* into_cset_dcq,
2183 bool concurrent,
2184 uint worker_i) {
2185 // Clean cards in the hot card cache
2186 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2187 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2188
2189 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2190 size_t n_completed_buffers = 0;
2191 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2192 n_completed_buffers++;
2193 }
2194 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2195 dcqs.clear_n_completed_buffers();
2196 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2197 }
2198
2199
2200 // Computes the sum of the storage used by the various regions.
2201 size_t G1CollectedHeap::used() const {
2202 return _allocator->used();
2203 }
2204
2205 size_t G1CollectedHeap::used_unlocked() const {
2206 return _allocator->used_unlocked();
2207 }
2208
2209 class SumUsedClosure: public HeapRegionClosure {
2210 size_t _used;
2211 public:
2212 SumUsedClosure() : _used(0) {}
2213 bool doHeapRegion(HeapRegion* r) {
2214 if (!r->is_continues_humongous()) {
2215 _used += r->used();
2216 }
2217 return false;
2218 }
2219 size_t result() { return _used; }
2220 };
2221
2222 size_t G1CollectedHeap::recalculate_used() const {
2223 double recalculate_used_start = os::elapsedTime();
2224
2225 SumUsedClosure blk;
2226 heap_region_iterate(&blk);
2227
2228 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2229 return blk.result();
2230 }
2231
2232 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2233 switch (cause) {
2234 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2235 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2236 case GCCause::_g1_humongous_allocation: return true;
2237 case GCCause::_update_allocation_context_stats_inc: return true;
2238 case GCCause::_wb_conc_mark: return true;
2239 default: return false;
2240 }
2241 }
2242
2243 #ifndef PRODUCT
2244 void G1CollectedHeap::allocate_dummy_regions() {
2245 // Let's fill up most of the region
2246 size_t word_size = HeapRegion::GrainWords - 1024;
2247 // And as a result the region we'll allocate will be humongous.
2248 guarantee(is_humongous(word_size), "sanity");
2249
2250 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2251 // Let's use the existing mechanism for the allocation
2252 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2253 AllocationContext::system());
2254 if (dummy_obj != NULL) {
2255 MemRegion mr(dummy_obj, word_size);
2256 CollectedHeap::fill_with_object(mr);
2257 } else {
2258 // If we can't allocate once, we probably cannot allocate
2259 // again. Let's get out of the loop.
2260 break;
2261 }
2262 }
2263 }
2264 #endif // !PRODUCT
2265
2266 void G1CollectedHeap::increment_old_marking_cycles_started() {
2267 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2268 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2269 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2270 _old_marking_cycles_started, _old_marking_cycles_completed));
2271
2272 _old_marking_cycles_started++;
2273 }
2274
2275 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2276 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2277
2278 // We assume that if concurrent == true, then the caller is a
2279 // concurrent thread that was joined the Suspendible Thread
2280 // Set. If there's ever a cheap way to check this, we should add an
2281 // assert here.
2282
2283 // Given that this method is called at the end of a Full GC or of a
2284 // concurrent cycle, and those can be nested (i.e., a Full GC can
2285 // interrupt a concurrent cycle), the number of full collections
2286 // completed should be either one (in the case where there was no
2287 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2288 // behind the number of full collections started.
2289
2290 // This is the case for the inner caller, i.e. a Full GC.
2291 assert(concurrent ||
2292 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2293 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2294 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2295 "is inconsistent with _old_marking_cycles_completed = %u",
2296 _old_marking_cycles_started, _old_marking_cycles_completed));
2297
2298 // This is the case for the outer caller, i.e. the concurrent cycle.
2299 assert(!concurrent ||
2300 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2301 err_msg("for outer caller (concurrent cycle): "
2302 "_old_marking_cycles_started = %u "
2303 "is inconsistent with _old_marking_cycles_completed = %u",
2304 _old_marking_cycles_started, _old_marking_cycles_completed));
2305
2306 _old_marking_cycles_completed += 1;
2307
2308 // We need to clear the "in_progress" flag in the CM thread before
2309 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2310 // is set) so that if a waiter requests another System.gc() it doesn't
2311 // incorrectly see that a marking cycle is still in progress.
2312 if (concurrent) {
2313 _cmThread->clear_in_progress();
2314 }
2315
2316 // This notify_all() will ensure that a thread that called
2317 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2318 // and it's waiting for a full GC to finish will be woken up. It is
2319 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2320 FullGCCount_lock->notify_all();
2321 }
2322
2323 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2324 _concurrent_cycle_started = true;
2325 _gc_timer_cm->register_gc_start(start_time);
2326
2327 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2328 trace_heap_before_gc(_gc_tracer_cm);
2329 }
2330
2331 void G1CollectedHeap::register_concurrent_cycle_end() {
2332 if (_concurrent_cycle_started) {
2333 if (_cm->has_aborted()) {
2334 _gc_tracer_cm->report_concurrent_mode_failure();
2335 }
2336
2337 _gc_timer_cm->register_gc_end();
2338 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2339
2340 // Clear state variables to prepare for the next concurrent cycle.
2341 _concurrent_cycle_started = false;
2342 _heap_summary_sent = false;
2343 }
2344 }
2345
2346 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2347 if (_concurrent_cycle_started) {
2348 // This function can be called when:
2349 // the cleanup pause is run
2350 // the concurrent cycle is aborted before the cleanup pause.
2351 // the concurrent cycle is aborted after the cleanup pause,
2352 // but before the concurrent cycle end has been registered.
2353 // Make sure that we only send the heap information once.
2354 if (!_heap_summary_sent) {
2355 trace_heap_after_gc(_gc_tracer_cm);
2356 _heap_summary_sent = true;
2357 }
2358 }
2359 }
2360
2361 G1YCType G1CollectedHeap::yc_type() {
2362 bool is_young = g1_policy()->gcs_are_young();
2363 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2364 bool is_during_mark = mark_in_progress();
2365
2366 if (is_initial_mark) {
2367 return InitialMark;
2368 } else if (is_during_mark) {
2369 return DuringMark;
2370 } else if (is_young) {
2371 return Normal;
2372 } else {
2373 return Mixed;
2374 }
2375 }
2376
2377 void G1CollectedHeap::collect(GCCause::Cause cause) {
2378 assert_heap_not_locked();
2379
2380 uint gc_count_before;
2381 uint old_marking_count_before;
2382 uint full_gc_count_before;
2383 bool retry_gc;
2384
2385 do {
2386 retry_gc = false;
2387
2388 {
2389 MutexLocker ml(Heap_lock);
2390
2391 // Read the GC count while holding the Heap_lock
2392 gc_count_before = total_collections();
2393 full_gc_count_before = total_full_collections();
2394 old_marking_count_before = _old_marking_cycles_started;
2395 }
2396
2397 if (should_do_concurrent_full_gc(cause)) {
2398 // Schedule an initial-mark evacuation pause that will start a
2399 // concurrent cycle. We're setting word_size to 0 which means that
2400 // we are not requesting a post-GC allocation.
2401 VM_G1IncCollectionPause op(gc_count_before,
2402 0, /* word_size */
2403 true, /* should_initiate_conc_mark */
2404 g1_policy()->max_pause_time_ms(),
2405 cause);
2406 op.set_allocation_context(AllocationContext::current());
2407
2408 VMThread::execute(&op);
2409 if (!op.pause_succeeded()) {
2410 if (old_marking_count_before == _old_marking_cycles_started) {
2411 retry_gc = op.should_retry_gc();
2412 } else {
2413 // A Full GC happened while we were trying to schedule the
2414 // initial-mark GC. No point in starting a new cycle given
2415 // that the whole heap was collected anyway.
2416 }
2417
2418 if (retry_gc) {
2419 if (GC_locker::is_active_and_needs_gc()) {
2420 GC_locker::stall_until_clear();
2421 }
2422 }
2423 }
2424 } else {
2425 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2426 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2427
2428 // Schedule a standard evacuation pause. We're setting word_size
2429 // to 0 which means that we are not requesting a post-GC allocation.
2430 VM_G1IncCollectionPause op(gc_count_before,
2431 0, /* word_size */
2432 false, /* should_initiate_conc_mark */
2433 g1_policy()->max_pause_time_ms(),
2434 cause);
2435 VMThread::execute(&op);
2436 } else {
2437 // Schedule a Full GC.
2438 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2439 VMThread::execute(&op);
2440 }
2441 }
2442 } while (retry_gc);
2443 }
2444
2445 bool G1CollectedHeap::is_in(const void* p) const {
2446 if (_hrm.reserved().contains(p)) {
2447 // Given that we know that p is in the reserved space,
2448 // heap_region_containing_raw() should successfully
2449 // return the containing region.
2450 HeapRegion* hr = heap_region_containing_raw(p);
2451 return hr->is_in(p);
2452 } else {
2453 return false;
2454 }
2455 }
2456
2457 #ifdef ASSERT
2458 bool G1CollectedHeap::is_in_exact(const void* p) const {
2459 bool contains = reserved_region().contains(p);
2460 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2461 if (contains && available) {
2462 return true;
2463 } else {
2464 return false;
2465 }
2466 }
2467 #endif
2468
2469 // Iteration functions.
2470
2471 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2472
2473 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2474 ExtendedOopClosure* _cl;
2475 public:
2476 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2477 bool doHeapRegion(HeapRegion* r) {
2478 if (!r->is_continues_humongous()) {
2479 r->oop_iterate(_cl);
2480 }
2481 return false;
2482 }
2483 };
2484
2485 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2486 IterateOopClosureRegionClosure blk(cl);
2487 heap_region_iterate(&blk);
2488 }
2489
2490 // Iterates an ObjectClosure over all objects within a HeapRegion.
2491
2492 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2493 ObjectClosure* _cl;
2494 public:
2495 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2496 bool doHeapRegion(HeapRegion* r) {
2497 if (!r->is_continues_humongous()) {
2498 r->object_iterate(_cl);
2499 }
2500 return false;
2501 }
2502 };
2503
2504 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2505 IterateObjectClosureRegionClosure blk(cl);
2506 heap_region_iterate(&blk);
2507 }
2508
2509 // Calls a SpaceClosure on a HeapRegion.
2510
2511 class SpaceClosureRegionClosure: public HeapRegionClosure {
2512 SpaceClosure* _cl;
2513 public:
2514 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2515 bool doHeapRegion(HeapRegion* r) {
2516 _cl->do_space(r);
2517 return false;
2518 }
2519 };
2520
2521 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2522 SpaceClosureRegionClosure blk(cl);
2523 heap_region_iterate(&blk);
2524 }
2525
2526 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2527 _hrm.iterate(cl);
2528 }
2529
2530 void
2531 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2532 uint worker_id,
2533 HeapRegionClaimer *hrclaimer,
2534 bool concurrent) const {
2535 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2536 }
2537
2538 // Clear the cached CSet starting regions and (more importantly)
2539 // the time stamps. Called when we reset the GC time stamp.
2540 void G1CollectedHeap::clear_cset_start_regions() {
2541 assert(_worker_cset_start_region != NULL, "sanity");
2542 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2543
2544 int n_queues = MAX2((int)ParallelGCThreads, 1);
2545 for (int i = 0; i < n_queues; i++) {
2546 _worker_cset_start_region[i] = NULL;
2547 _worker_cset_start_region_time_stamp[i] = 0;
2548 }
2549 }
2550
2551 // Given the id of a worker, obtain or calculate a suitable
2552 // starting region for iterating over the current collection set.
2553 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2554 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2555
2556 HeapRegion* result = NULL;
2557 unsigned gc_time_stamp = get_gc_time_stamp();
2558
2559 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2560 // Cached starting region for current worker was set
2561 // during the current pause - so it's valid.
2562 // Note: the cached starting heap region may be NULL
2563 // (when the collection set is empty).
2564 result = _worker_cset_start_region[worker_i];
2565 assert(result == NULL || result->in_collection_set(), "sanity");
2566 return result;
2567 }
2568
2569 // The cached entry was not valid so let's calculate
2570 // a suitable starting heap region for this worker.
2571
2572 // We want the parallel threads to start their collection
2573 // set iteration at different collection set regions to
2574 // avoid contention.
2575 // If we have:
2576 // n collection set regions
2577 // p threads
2578 // Then thread t will start at region floor ((t * n) / p)
2579
2580 result = g1_policy()->collection_set();
2581 uint cs_size = g1_policy()->cset_region_length();
2582 uint active_workers = workers()->active_workers();
2583 assert(UseDynamicNumberOfGCThreads ||
2584 active_workers == workers()->total_workers(),
2585 "Unless dynamic should use total workers");
2586
2587 uint end_ind = (cs_size * worker_i) / active_workers;
2588 uint start_ind = 0;
2589
2590 if (worker_i > 0 &&
2591 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2592 // Previous workers starting region is valid
2593 // so let's iterate from there
2594 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2595 result = _worker_cset_start_region[worker_i - 1];
2596 }
2597
2598 for (uint i = start_ind; i < end_ind; i++) {
2599 result = result->next_in_collection_set();
2600 }
2601
2602 // Note: the calculated starting heap region may be NULL
2603 // (when the collection set is empty).
2604 assert(result == NULL || result->in_collection_set(), "sanity");
2605 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2606 "should be updated only once per pause");
2607 _worker_cset_start_region[worker_i] = result;
2608 OrderAccess::storestore();
2609 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2610 return result;
2611 }
2612
2613 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2614 HeapRegion* r = g1_policy()->collection_set();
2615 while (r != NULL) {
2616 HeapRegion* next = r->next_in_collection_set();
2617 if (cl->doHeapRegion(r)) {
2618 cl->incomplete();
2619 return;
2620 }
2621 r = next;
2622 }
2623 }
2624
2625 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2626 HeapRegionClosure *cl) {
2627 if (r == NULL) {
2628 // The CSet is empty so there's nothing to do.
2629 return;
2630 }
2631
2632 assert(r->in_collection_set(),
2633 "Start region must be a member of the collection set.");
2634 HeapRegion* cur = r;
2635 while (cur != NULL) {
2636 HeapRegion* next = cur->next_in_collection_set();
2637 if (cl->doHeapRegion(cur) && false) {
2638 cl->incomplete();
2639 return;
2640 }
2641 cur = next;
2642 }
2643 cur = g1_policy()->collection_set();
2644 while (cur != r) {
2645 HeapRegion* next = cur->next_in_collection_set();
2646 if (cl->doHeapRegion(cur) && false) {
2647 cl->incomplete();
2648 return;
2649 }
2650 cur = next;
2651 }
2652 }
2653
2654 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2655 HeapRegion* result = _hrm.next_region_in_heap(from);
2656 while (result != NULL && result->is_humongous()) {
2657 result = _hrm.next_region_in_heap(result);
2658 }
2659 return result;
2660 }
2661
2662 Space* G1CollectedHeap::space_containing(const void* addr) const {
2663 return heap_region_containing(addr);
2664 }
2665
2666 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2667 Space* sp = space_containing(addr);
2668 return sp->block_start(addr);
2669 }
2670
2671 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2672 Space* sp = space_containing(addr);
2673 return sp->block_size(addr);
2674 }
2675
2676 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2677 Space* sp = space_containing(addr);
2678 return sp->block_is_obj(addr);
2679 }
2680
2681 bool G1CollectedHeap::supports_tlab_allocation() const {
2682 return true;
2683 }
2684
2685 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2686 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2687 }
2688
2689 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2690 return young_list()->eden_used_bytes();
2691 }
2692
2693 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2694 // must be smaller than the humongous object limit.
2695 size_t G1CollectedHeap::max_tlab_size() const {
2696 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2697 }
2698
2699 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2700 // Return the remaining space in the cur alloc region, but not less than
2701 // the min TLAB size.
2702
2703 // Also, this value can be at most the humongous object threshold,
2704 // since we can't allow tlabs to grow big enough to accommodate
2705 // humongous objects.
2706
2707 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2708 size_t max_tlab = max_tlab_size() * wordSize;
2709 if (hr == NULL) {
2710 return max_tlab;
2711 } else {
2712 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2713 }
2714 }
2715
2716 size_t G1CollectedHeap::max_capacity() const {
2717 return _hrm.reserved().byte_size();
2718 }
2719
2720 jlong G1CollectedHeap::millis_since_last_gc() {
2721 // assert(false, "NYI");
2722 return 0;
2723 }
2724
2725 void G1CollectedHeap::prepare_for_verify() {
2726 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2727 ensure_parsability(false);
2728 }
2729 g1_rem_set()->prepare_for_verify();
2730 }
2731
2732 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2733 VerifyOption vo) {
2734 switch (vo) {
2735 case VerifyOption_G1UsePrevMarking:
2736 return hr->obj_allocated_since_prev_marking(obj);
2737 case VerifyOption_G1UseNextMarking:
2738 return hr->obj_allocated_since_next_marking(obj);
2739 case VerifyOption_G1UseMarkWord:
2740 return false;
2741 default:
2742 ShouldNotReachHere();
2743 }
2744 return false; // keep some compilers happy
2745 }
2746
2747 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2748 switch (vo) {
2749 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2750 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2751 case VerifyOption_G1UseMarkWord: return NULL;
2752 default: ShouldNotReachHere();
2753 }
2754 return NULL; // keep some compilers happy
2755 }
2756
2757 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2758 switch (vo) {
2759 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2760 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2761 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2762 default: ShouldNotReachHere();
2763 }
2764 return false; // keep some compilers happy
2765 }
2766
2767 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2768 switch (vo) {
2769 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2770 case VerifyOption_G1UseNextMarking: return "NTAMS";
2771 case VerifyOption_G1UseMarkWord: return "NONE";
2772 default: ShouldNotReachHere();
2773 }
2774 return NULL; // keep some compilers happy
2775 }
2776
2777 class VerifyRootsClosure: public OopClosure {
2778 private:
2779 G1CollectedHeap* _g1h;
2780 VerifyOption _vo;
2781 bool _failures;
2782 public:
2783 // _vo == UsePrevMarking -> use "prev" marking information,
2784 // _vo == UseNextMarking -> use "next" marking information,
2785 // _vo == UseMarkWord -> use mark word from object header.
2786 VerifyRootsClosure(VerifyOption vo) :
2787 _g1h(G1CollectedHeap::heap()),
2788 _vo(vo),
2789 _failures(false) { }
2790
2791 bool failures() { return _failures; }
2792
2793 template <class T> void do_oop_nv(T* p) {
2794 T heap_oop = oopDesc::load_heap_oop(p);
2795 if (!oopDesc::is_null(heap_oop)) {
2796 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2797 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2798 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2799 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2800 if (_vo == VerifyOption_G1UseMarkWord) {
2801 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2802 }
2803 obj->print_on(gclog_or_tty);
2804 _failures = true;
2805 }
2806 }
2807 }
2808
2809 void do_oop(oop* p) { do_oop_nv(p); }
2810 void do_oop(narrowOop* p) { do_oop_nv(p); }
2811 };
2812
2813 class G1VerifyCodeRootOopClosure: public OopClosure {
2814 G1CollectedHeap* _g1h;
2815 OopClosure* _root_cl;
2816 nmethod* _nm;
2817 VerifyOption _vo;
2818 bool _failures;
2819
2820 template <class T> void do_oop_work(T* p) {
2821 // First verify that this root is live
2822 _root_cl->do_oop(p);
2823
2824 if (!G1VerifyHeapRegionCodeRoots) {
2825 // We're not verifying the code roots attached to heap region.
2826 return;
2827 }
2828
2829 // Don't check the code roots during marking verification in a full GC
2830 if (_vo == VerifyOption_G1UseMarkWord) {
2831 return;
2832 }
2833
2834 // Now verify that the current nmethod (which contains p) is
2835 // in the code root list of the heap region containing the
2836 // object referenced by p.
2837
2838 T heap_oop = oopDesc::load_heap_oop(p);
2839 if (!oopDesc::is_null(heap_oop)) {
2840 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2841
2842 // Now fetch the region containing the object
2843 HeapRegion* hr = _g1h->heap_region_containing(obj);
2844 HeapRegionRemSet* hrrs = hr->rem_set();
2845 // Verify that the strong code root list for this region
2846 // contains the nmethod
2847 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2848 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2849 "from nmethod "PTR_FORMAT" not in strong "
2850 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2851 p, _nm, hr->bottom(), hr->end());
2852 _failures = true;
2853 }
2854 }
2855 }
2856
2857 public:
2858 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2859 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2860
2861 void do_oop(oop* p) { do_oop_work(p); }
2862 void do_oop(narrowOop* p) { do_oop_work(p); }
2863
2864 void set_nmethod(nmethod* nm) { _nm = nm; }
2865 bool failures() { return _failures; }
2866 };
2867
2868 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2869 G1VerifyCodeRootOopClosure* _oop_cl;
2870
2871 public:
2872 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2873 _oop_cl(oop_cl) {}
2874
2875 void do_code_blob(CodeBlob* cb) {
2876 nmethod* nm = cb->as_nmethod_or_null();
2877 if (nm != NULL) {
2878 _oop_cl->set_nmethod(nm);
2879 nm->oops_do(_oop_cl);
2880 }
2881 }
2882 };
2883
2884 class YoungRefCounterClosure : public OopClosure {
2885 G1CollectedHeap* _g1h;
2886 int _count;
2887 public:
2888 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2889 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2890 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2891
2892 int count() { return _count; }
2893 void reset_count() { _count = 0; };
2894 };
2895
2896 class VerifyKlassClosure: public KlassClosure {
2897 YoungRefCounterClosure _young_ref_counter_closure;
2898 OopClosure *_oop_closure;
2899 public:
2900 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2901 void do_klass(Klass* k) {
2902 k->oops_do(_oop_closure);
2903
2904 _young_ref_counter_closure.reset_count();
2905 k->oops_do(&_young_ref_counter_closure);
2906 if (_young_ref_counter_closure.count() > 0) {
2907 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2908 }
2909 }
2910 };
2911
2912 class VerifyLivenessOopClosure: public OopClosure {
2913 G1CollectedHeap* _g1h;
2914 VerifyOption _vo;
2915 public:
2916 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2917 _g1h(g1h), _vo(vo)
2918 { }
2919 void do_oop(narrowOop *p) { do_oop_work(p); }
2920 void do_oop( oop *p) { do_oop_work(p); }
2921
2922 template <class T> void do_oop_work(T *p) {
2923 oop obj = oopDesc::load_decode_heap_oop(p);
2924 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2925 "Dead object referenced by a not dead object");
2926 }
2927 };
2928
2929 class VerifyObjsInRegionClosure: public ObjectClosure {
2930 private:
2931 G1CollectedHeap* _g1h;
2932 size_t _live_bytes;
2933 HeapRegion *_hr;
2934 VerifyOption _vo;
2935 public:
2936 // _vo == UsePrevMarking -> use "prev" marking information,
2937 // _vo == UseNextMarking -> use "next" marking information,
2938 // _vo == UseMarkWord -> use mark word from object header.
2939 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2940 : _live_bytes(0), _hr(hr), _vo(vo) {
2941 _g1h = G1CollectedHeap::heap();
2942 }
2943 void do_object(oop o) {
2944 VerifyLivenessOopClosure isLive(_g1h, _vo);
2945 assert(o != NULL, "Huh?");
2946 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2947 // If the object is alive according to the mark word,
2948 // then verify that the marking information agrees.
2949 // Note we can't verify the contra-positive of the
2950 // above: if the object is dead (according to the mark
2951 // word), it may not be marked, or may have been marked
2952 // but has since became dead, or may have been allocated
2953 // since the last marking.
2954 if (_vo == VerifyOption_G1UseMarkWord) {
2955 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2956 }
2957
2958 o->oop_iterate_no_header(&isLive);
2959 if (!_hr->obj_allocated_since_prev_marking(o)) {
2960 size_t obj_size = o->size(); // Make sure we don't overflow
2961 _live_bytes += (obj_size * HeapWordSize);
2962 }
2963 }
2964 }
2965 size_t live_bytes() { return _live_bytes; }
2966 };
2967
2968 class PrintObjsInRegionClosure : public ObjectClosure {
2969 HeapRegion *_hr;
2970 G1CollectedHeap *_g1;
2971 public:
2972 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2973 _g1 = G1CollectedHeap::heap();
2974 };
2975
2976 void do_object(oop o) {
2977 if (o != NULL) {
2978 HeapWord *start = (HeapWord *) o;
2979 size_t word_sz = o->size();
2980 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2981 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2982 (void*) o, word_sz,
2983 _g1->isMarkedPrev(o),
2984 _g1->isMarkedNext(o),
2985 _hr->obj_allocated_since_prev_marking(o));
2986 HeapWord *end = start + word_sz;
2987 HeapWord *cur;
2988 int *val;
2989 for (cur = start; cur < end; cur++) {
2990 val = (int *) cur;
2991 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2992 }
2993 }
2994 }
2995 };
2996
2997 class VerifyRegionClosure: public HeapRegionClosure {
2998 private:
2999 bool _par;
3000 VerifyOption _vo;
3001 bool _failures;
3002 public:
3003 // _vo == UsePrevMarking -> use "prev" marking information,
3004 // _vo == UseNextMarking -> use "next" marking information,
3005 // _vo == UseMarkWord -> use mark word from object header.
3006 VerifyRegionClosure(bool par, VerifyOption vo)
3007 : _par(par),
3008 _vo(vo),
3009 _failures(false) {}
3010
3011 bool failures() {
3012 return _failures;
3013 }
3014
3015 bool doHeapRegion(HeapRegion* r) {
3016 if (!r->is_continues_humongous()) {
3017 bool failures = false;
3018 r->verify(_vo, &failures);
3019 if (failures) {
3020 _failures = true;
3021 } else {
3022 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3023 r->object_iterate(¬_dead_yet_cl);
3024 if (_vo != VerifyOption_G1UseNextMarking) {
3025 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3026 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3027 "max_live_bytes "SIZE_FORMAT" "
3028 "< calculated "SIZE_FORMAT,
3029 r->bottom(), r->end(),
3030 r->max_live_bytes(),
3031 not_dead_yet_cl.live_bytes());
3032 _failures = true;
3033 }
3034 } else {
3035 // When vo == UseNextMarking we cannot currently do a sanity
3036 // check on the live bytes as the calculation has not been
3037 // finalized yet.
3038 }
3039 }
3040 }
3041 return false; // stop the region iteration if we hit a failure
3042 }
3043 };
3044
3045 // This is the task used for parallel verification of the heap regions
3046
3047 class G1ParVerifyTask: public AbstractGangTask {
3048 private:
3049 G1CollectedHeap* _g1h;
3050 VerifyOption _vo;
3051 bool _failures;
3052 HeapRegionClaimer _hrclaimer;
3053
3054 public:
3055 // _vo == UsePrevMarking -> use "prev" marking information,
3056 // _vo == UseNextMarking -> use "next" marking information,
3057 // _vo == UseMarkWord -> use mark word from object header.
3058 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3059 AbstractGangTask("Parallel verify task"),
3060 _g1h(g1h),
3061 _vo(vo),
3062 _failures(false),
3063 _hrclaimer(g1h->workers()->active_workers()) {}
3064
3065 bool failures() {
3066 return _failures;
3067 }
3068
3069 void work(uint worker_id) {
3070 HandleMark hm;
3071 VerifyRegionClosure blk(true, _vo);
3072 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3073 if (blk.failures()) {
3074 _failures = true;
3075 }
3076 }
3077 };
3078
3079 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3080 if (SafepointSynchronize::is_at_safepoint()) {
3081 assert(Thread::current()->is_VM_thread(),
3082 "Expected to be executed serially by the VM thread at this point");
3083
3084 if (!silent) { gclog_or_tty->print("Roots "); }
3085 VerifyRootsClosure rootsCl(vo);
3086 VerifyKlassClosure klassCl(this, &rootsCl);
3087 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3088
3089 // We apply the relevant closures to all the oops in the
3090 // system dictionary, class loader data graph, the string table
3091 // and the nmethods in the code cache.
3092 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3093 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3094
3095 {
3096 G1RootProcessor root_processor(this, false /* trace_metadata */);
3097 root_processor.process_all_roots(&rootsCl,
3098 &cldCl,
3099 &blobsCl);
3100 }
3101
3102 bool failures = rootsCl.failures() || codeRootsCl.failures();
3103
3104 if (vo != VerifyOption_G1UseMarkWord) {
3105 // If we're verifying during a full GC then the region sets
3106 // will have been torn down at the start of the GC. Therefore
3107 // verifying the region sets will fail. So we only verify
3108 // the region sets when not in a full GC.
3109 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3110 verify_region_sets();
3111 }
3112
3113 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3114 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3115
3116 G1ParVerifyTask task(this, vo);
3117 assert(UseDynamicNumberOfGCThreads ||
3118 workers()->active_workers() == workers()->total_workers(),
3119 "If not dynamic should be using all the workers");
3120 int n_workers = workers()->active_workers();
3121 set_par_threads(n_workers);
3122 workers()->run_task(&task);
3123 set_par_threads(0);
3124 if (task.failures()) {
3125 failures = true;
3126 }
3127
3128 } else {
3129 VerifyRegionClosure blk(false, vo);
3130 heap_region_iterate(&blk);
3131 if (blk.failures()) {
3132 failures = true;
3133 }
3134 }
3135
3136 if (G1StringDedup::is_enabled()) {
3137 if (!silent) gclog_or_tty->print("StrDedup ");
3138 G1StringDedup::verify();
3139 }
3140
3141 if (failures) {
3142 gclog_or_tty->print_cr("Heap:");
3143 // It helps to have the per-region information in the output to
3144 // help us track down what went wrong. This is why we call
3145 // print_extended_on() instead of print_on().
3146 print_extended_on(gclog_or_tty);
3147 gclog_or_tty->cr();
3148 #ifndef PRODUCT
3149 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3150 concurrent_mark()->print_reachable("at-verification-failure",
3151 vo, false /* all */);
3152 }
3153 #endif
3154 gclog_or_tty->flush();
3155 }
3156 guarantee(!failures, "there should not have been any failures");
3157 } else {
3158 if (!silent) {
3159 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3160 if (G1StringDedup::is_enabled()) {
3161 gclog_or_tty->print(", StrDedup");
3162 }
3163 gclog_or_tty->print(") ");
3164 }
3165 }
3166 }
3167
3168 void G1CollectedHeap::verify(bool silent) {
3169 verify(silent, VerifyOption_G1UsePrevMarking);
3170 }
3171
3172 double G1CollectedHeap::verify(bool guard, const char* msg) {
3173 double verify_time_ms = 0.0;
3174
3175 if (guard && total_collections() >= VerifyGCStartAt) {
3176 double verify_start = os::elapsedTime();
3177 HandleMark hm; // Discard invalid handles created during verification
3178 prepare_for_verify();
3179 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3180 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3181 }
3182
3183 return verify_time_ms;
3184 }
3185
3186 void G1CollectedHeap::verify_before_gc() {
3187 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3188 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3189 }
3190
3191 void G1CollectedHeap::verify_after_gc() {
3192 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3193 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3194 }
3195
3196 class PrintRegionClosure: public HeapRegionClosure {
3197 outputStream* _st;
3198 public:
3199 PrintRegionClosure(outputStream* st) : _st(st) {}
3200 bool doHeapRegion(HeapRegion* r) {
3201 r->print_on(_st);
3202 return false;
3203 }
3204 };
3205
3206 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3207 const HeapRegion* hr,
3208 const VerifyOption vo) const {
3209 switch (vo) {
3210 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3211 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3212 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3213 default: ShouldNotReachHere();
3214 }
3215 return false; // keep some compilers happy
3216 }
3217
3218 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3219 const VerifyOption vo) const {
3220 switch (vo) {
3221 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3222 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3223 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3224 default: ShouldNotReachHere();
3225 }
3226 return false; // keep some compilers happy
3227 }
3228
3229 void G1CollectedHeap::print_on(outputStream* st) const {
3230 st->print(" %-20s", "garbage-first heap");
3231 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3232 capacity()/K, used_unlocked()/K);
3233 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3234 _hrm.reserved().start(),
3235 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3236 _hrm.reserved().end());
3237 st->cr();
3238 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3239 uint young_regions = _young_list->length();
3240 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3241 (size_t) young_regions * HeapRegion::GrainBytes / K);
3242 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3243 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3244 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3245 st->cr();
3246 MetaspaceAux::print_on(st);
3247 }
3248
3249 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3250 print_on(st);
3251
3252 // Print the per-region information.
3253 st->cr();
3254 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3255 "HS=humongous(starts), HC=humongous(continues), "
3256 "CS=collection set, F=free, TS=gc time stamp, "
3257 "PTAMS=previous top-at-mark-start, "
3258 "NTAMS=next top-at-mark-start)");
3259 PrintRegionClosure blk(st);
3260 heap_region_iterate(&blk);
3261 }
3262
3263 void G1CollectedHeap::print_on_error(outputStream* st) const {
3264 this->CollectedHeap::print_on_error(st);
3265
3266 if (_cm != NULL) {
3267 st->cr();
3268 _cm->print_on_error(st);
3269 }
3270 }
3271
3272 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3273 workers()->print_worker_threads_on(st);
3274 _cmThread->print_on(st);
3275 st->cr();
3276 _cm->print_worker_threads_on(st);
3277 _cg1r->print_worker_threads_on(st);
3278 if (G1StringDedup::is_enabled()) {
3279 G1StringDedup::print_worker_threads_on(st);
3280 }
3281 }
3282
3283 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3284 workers()->threads_do(tc);
3285 tc->do_thread(_cmThread);
3286 _cg1r->threads_do(tc);
3287 if (G1StringDedup::is_enabled()) {
3288 G1StringDedup::threads_do(tc);
3289 }
3290 }
3291
3292 void G1CollectedHeap::print_tracing_info() const {
3293 // We'll overload this to mean "trace GC pause statistics."
3294 if (TraceYoungGenTime || TraceOldGenTime) {
3295 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3296 // to that.
3297 g1_policy()->print_tracing_info();
3298 }
3299 if (G1SummarizeRSetStats) {
3300 g1_rem_set()->print_summary_info();
3301 }
3302 if (G1SummarizeConcMark) {
3303 concurrent_mark()->print_summary_info();
3304 }
3305 g1_policy()->print_yg_surv_rate_info();
3306 }
3307
3308 #ifndef PRODUCT
3309 // Helpful for debugging RSet issues.
3310
3311 class PrintRSetsClosure : public HeapRegionClosure {
3312 private:
3313 const char* _msg;
3314 size_t _occupied_sum;
3315
3316 public:
3317 bool doHeapRegion(HeapRegion* r) {
3318 HeapRegionRemSet* hrrs = r->rem_set();
3319 size_t occupied = hrrs->occupied();
3320 _occupied_sum += occupied;
3321
3322 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3323 HR_FORMAT_PARAMS(r));
3324 if (occupied == 0) {
3325 gclog_or_tty->print_cr(" RSet is empty");
3326 } else {
3327 hrrs->print();
3328 }
3329 gclog_or_tty->print_cr("----------");
3330 return false;
3331 }
3332
3333 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3334 gclog_or_tty->cr();
3335 gclog_or_tty->print_cr("========================================");
3336 gclog_or_tty->print_cr("%s", msg);
3337 gclog_or_tty->cr();
3338 }
3339
3340 ~PrintRSetsClosure() {
3341 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3342 gclog_or_tty->print_cr("========================================");
3343 gclog_or_tty->cr();
3344 }
3345 };
3346
3347 void G1CollectedHeap::print_cset_rsets() {
3348 PrintRSetsClosure cl("Printing CSet RSets");
3349 collection_set_iterate(&cl);
3350 }
3351
3352 void G1CollectedHeap::print_all_rsets() {
3353 PrintRSetsClosure cl("Printing All RSets");;
3354 heap_region_iterate(&cl);
3355 }
3356 #endif // PRODUCT
3357
3358 G1CollectedHeap* G1CollectedHeap::heap() {
3359 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3360 "not a garbage-first heap");
3361 return _g1h;
3362 }
3363
3364 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3365 // always_do_update_barrier = false;
3366 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3367 // Fill TLAB's and such
3368 accumulate_statistics_all_tlabs();
3369 ensure_parsability(true);
3370
3371 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3372 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3373 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3374 }
3375 }
3376
3377 void G1CollectedHeap::gc_epilogue(bool full) {
3378
3379 if (G1SummarizeRSetStats &&
3380 (G1SummarizeRSetStatsPeriod > 0) &&
3381 // we are at the end of the GC. Total collections has already been increased.
3382 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3383 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3384 }
3385
3386 // FIXME: what is this about?
3387 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3388 // is set.
3389 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3390 "derived pointer present"));
3391 // always_do_update_barrier = true;
3392
3393 resize_all_tlabs();
3394 allocation_context_stats().update(full);
3395
3396 // We have just completed a GC. Update the soft reference
3397 // policy with the new heap occupancy
3398 Universe::update_heap_info_at_gc();
3399 }
3400
3401 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3402 uint gc_count_before,
3403 bool* succeeded,
3404 GCCause::Cause gc_cause) {
3405 assert_heap_not_locked_and_not_at_safepoint();
3406 g1_policy()->record_stop_world_start();
3407 VM_G1IncCollectionPause op(gc_count_before,
3408 word_size,
3409 false, /* should_initiate_conc_mark */
3410 g1_policy()->max_pause_time_ms(),
3411 gc_cause);
3412
3413 op.set_allocation_context(AllocationContext::current());
3414 VMThread::execute(&op);
3415
3416 HeapWord* result = op.result();
3417 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3418 assert(result == NULL || ret_succeeded,
3419 "the result should be NULL if the VM did not succeed");
3420 *succeeded = ret_succeeded;
3421
3422 assert_heap_not_locked();
3423 return result;
3424 }
3425
3426 void
3427 G1CollectedHeap::doConcurrentMark() {
3428 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3429 if (!_cmThread->in_progress()) {
3430 _cmThread->set_started();
3431 CGC_lock->notify();
3432 }
3433 }
3434
3435 size_t G1CollectedHeap::pending_card_num() {
3436 size_t extra_cards = 0;
3437 JavaThread *curr = Threads::first();
3438 while (curr != NULL) {
3439 DirtyCardQueue& dcq = curr->dirty_card_queue();
3440 extra_cards += dcq.size();
3441 curr = curr->next();
3442 }
3443 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3444 size_t buffer_size = dcqs.buffer_size();
3445 size_t buffer_num = dcqs.completed_buffers_num();
3446
3447 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3448 // in bytes - not the number of 'entries'. We need to convert
3449 // into a number of cards.
3450 return (buffer_size * buffer_num + extra_cards) / oopSize;
3451 }
3452
3453 size_t G1CollectedHeap::cards_scanned() {
3454 return g1_rem_set()->cardsScanned();
3455 }
3456
3457 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3458 HeapRegion* region = region_at(index);
3459 assert(region->is_starts_humongous(), "Must start a humongous object");
3460 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3461 }
3462
3463 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3464 private:
3465 size_t _total_humongous;
3466 size_t _candidate_humongous;
3467
3468 DirtyCardQueue _dcq;
3469
3470 bool humongous_region_is_candidate(uint index) {
3471 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3472 assert(region->is_starts_humongous(), "Must start a humongous object");
3473 HeapRegionRemSet* const rset = region->rem_set();
3474 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3475 return !oop(region->bottom())->is_objArray() &&
3476 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3477 (!allow_stale_refs && rset->is_empty()));
3478 }
3479
3480 public:
3481 RegisterHumongousWithInCSetFastTestClosure()
3482 : _total_humongous(0),
3483 _candidate_humongous(0),
3484 _dcq(&JavaThread::dirty_card_queue_set()) {
3485 }
3486
3487 virtual bool doHeapRegion(HeapRegion* r) {
3488 if (!r->is_starts_humongous()) {
3489 return false;
3490 }
3491 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3492
3493 uint region_idx = r->hrm_index();
3494 bool is_candidate = humongous_region_is_candidate(region_idx);
3495 // Is_candidate already filters out humongous object with large remembered sets.
3496 // If we have a humongous object with a few remembered sets, we simply flush these
3497 // remembered set entries into the DCQS. That will result in automatic
3498 // re-evaluation of their remembered set entries during the following evacuation
3499 // phase.
3500 if (is_candidate) {
3501 if (!r->rem_set()->is_empty()) {
3502 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3503 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3504 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3505 HeapRegionRemSetIterator hrrs(r->rem_set());
3506 size_t card_index;
3507 while (hrrs.has_next(card_index)) {
3508 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3509 // The remembered set might contain references to already freed
3510 // regions. Filter out such entries to avoid failing card table
3511 // verification.
3512 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3513 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3514 *card_ptr = CardTableModRefBS::dirty_card_val();
3515 _dcq.enqueue(card_ptr);
3516 }
3517 }
3518 }
3519 r->rem_set()->clear_locked();
3520 }
3521 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3522 g1h->register_humongous_region_with_cset(region_idx);
3523 _candidate_humongous++;
3524 }
3525 _total_humongous++;
3526
3527 return false;
3528 }
3529
3530 size_t total_humongous() const { return _total_humongous; }
3531 size_t candidate_humongous() const { return _candidate_humongous; }
3532
3533 void flush_rem_set_entries() { _dcq.flush(); }
3534 };
3535
3536 void G1CollectedHeap::register_humongous_regions_with_cset() {
3537 if (!G1EagerReclaimHumongousObjects) {
3538 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3539 return;
3540 }
3541 double time = os::elapsed_counter();
3542
3543 RegisterHumongousWithInCSetFastTestClosure cl;
3544 heap_region_iterate(&cl);
3545
3546 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3547 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3548 cl.total_humongous(),
3549 cl.candidate_humongous());
3550 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3551
3552 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3553 clear_humongous_is_live_table();
3554 }
3555
3556 // Finally flush all remembered set entries to re-check into the global DCQS.
3557 cl.flush_rem_set_entries();
3558 }
3559
3560 void
3561 G1CollectedHeap::setup_surviving_young_words() {
3562 assert(_surviving_young_words == NULL, "pre-condition");
3563 uint array_length = g1_policy()->young_cset_region_length();
3564 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3565 if (_surviving_young_words == NULL) {
3566 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3567 "Not enough space for young surv words summary.");
3568 }
3569 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3570 #ifdef ASSERT
3571 for (uint i = 0; i < array_length; ++i) {
3572 assert( _surviving_young_words[i] == 0, "memset above" );
3573 }
3574 #endif // !ASSERT
3575 }
3576
3577 void
3578 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3579 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3580 uint array_length = g1_policy()->young_cset_region_length();
3581 for (uint i = 0; i < array_length; ++i) {
3582 _surviving_young_words[i] += surv_young_words[i];
3583 }
3584 }
3585
3586 void
3587 G1CollectedHeap::cleanup_surviving_young_words() {
3588 guarantee( _surviving_young_words != NULL, "pre-condition" );
3589 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3590 _surviving_young_words = NULL;
3591 }
3592
3593 #ifdef ASSERT
3594 class VerifyCSetClosure: public HeapRegionClosure {
3595 public:
3596 bool doHeapRegion(HeapRegion* hr) {
3597 // Here we check that the CSet region's RSet is ready for parallel
3598 // iteration. The fields that we'll verify are only manipulated
3599 // when the region is part of a CSet and is collected. Afterwards,
3600 // we reset these fields when we clear the region's RSet (when the
3601 // region is freed) so they are ready when the region is
3602 // re-allocated. The only exception to this is if there's an
3603 // evacuation failure and instead of freeing the region we leave
3604 // it in the heap. In that case, we reset these fields during
3605 // evacuation failure handling.
3606 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3607
3608 // Here's a good place to add any other checks we'd like to
3609 // perform on CSet regions.
3610 return false;
3611 }
3612 };
3613 #endif // ASSERT
3614
3615 #if TASKQUEUE_STATS
3616 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3617 st->print_raw_cr("GC Task Stats");
3618 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3619 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3620 }
3621
3622 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3623 print_taskqueue_stats_hdr(st);
3624
3625 TaskQueueStats totals;
3626 const int n = workers()->total_workers();
3627 for (int i = 0; i < n; ++i) {
3628 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3629 totals += task_queue(i)->stats;
3630 }
3631 st->print_raw("tot "); totals.print(st); st->cr();
3632
3633 DEBUG_ONLY(totals.verify());
3634 }
3635
3636 void G1CollectedHeap::reset_taskqueue_stats() {
3637 const int n = workers()->total_workers();
3638 for (int i = 0; i < n; ++i) {
3639 task_queue(i)->stats.reset();
3640 }
3641 }
3642 #endif // TASKQUEUE_STATS
3643
3644 void G1CollectedHeap::log_gc_header() {
3645 if (!G1Log::fine()) {
3646 return;
3647 }
3648
3649 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3650
3651 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3652 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3653 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3654
3655 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3656 }
3657
3658 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3659 if (!G1Log::fine()) {
3660 return;
3661 }
3662
3663 if (G1Log::finer()) {
3664 if (evacuation_failed()) {
3665 gclog_or_tty->print(" (to-space exhausted)");
3666 }
3667 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3668 g1_policy()->phase_times()->note_gc_end();
3669 g1_policy()->phase_times()->print(pause_time_sec);
3670 g1_policy()->print_detailed_heap_transition();
3671 } else {
3672 if (evacuation_failed()) {
3673 gclog_or_tty->print("--");
3674 }
3675 g1_policy()->print_heap_transition();
3676 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3677 }
3678 gclog_or_tty->flush();
3679 }
3680
3681 bool
3682 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3683 assert_at_safepoint(true /* should_be_vm_thread */);
3684 guarantee(!is_gc_active(), "collection is not reentrant");
3685
3686 if (GC_locker::check_active_before_gc()) {
3687 return false;
3688 }
3689
3690 _gc_timer_stw->register_gc_start();
3691
3692 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3693
3694 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3695 ResourceMark rm;
3696
3697 print_heap_before_gc();
3698 trace_heap_before_gc(_gc_tracer_stw);
3699
3700 verify_region_sets_optional();
3701 verify_dirty_young_regions();
3702
3703 // This call will decide whether this pause is an initial-mark
3704 // pause. If it is, during_initial_mark_pause() will return true
3705 // for the duration of this pause.
3706 g1_policy()->decide_on_conc_mark_initiation();
3707
3708 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3709 assert(!g1_policy()->during_initial_mark_pause() ||
3710 g1_policy()->gcs_are_young(), "sanity");
3711
3712 // We also do not allow mixed GCs during marking.
3713 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3714
3715 // Record whether this pause is an initial mark. When the current
3716 // thread has completed its logging output and it's safe to signal
3717 // the CM thread, the flag's value in the policy has been reset.
3718 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3719
3720 // Inner scope for scope based logging, timers, and stats collection
3721 {
3722 EvacuationInfo evacuation_info;
3723
3724 if (g1_policy()->during_initial_mark_pause()) {
3725 // We are about to start a marking cycle, so we increment the
3726 // full collection counter.
3727 increment_old_marking_cycles_started();
3728 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3729 }
3730
3731 _gc_tracer_stw->report_yc_type(yc_type());
3732
3733 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3734
3735 uint active_workers = workers()->active_workers();
3736 double pause_start_sec = os::elapsedTime();
3737 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3738 log_gc_header();
3739
3740 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3741 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3742
3743 // If the secondary_free_list is not empty, append it to the
3744 // free_list. No need to wait for the cleanup operation to finish;
3745 // the region allocation code will check the secondary_free_list
3746 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3747 // set, skip this step so that the region allocation code has to
3748 // get entries from the secondary_free_list.
3749 if (!G1StressConcRegionFreeing) {
3750 append_secondary_free_list_if_not_empty_with_lock();
3751 }
3752
3753 assert(check_young_list_well_formed(), "young list should be well formed");
3754
3755 // Don't dynamically change the number of GC threads this early. A value of
3756 // 0 is used to indicate serial work. When parallel work is done,
3757 // it will be set.
3758
3759 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3760 IsGCActiveMark x;
3761
3762 gc_prologue(false);
3763 increment_total_collections(false /* full gc */);
3764 increment_gc_time_stamp();
3765
3766 verify_before_gc();
3767
3768 check_bitmaps("GC Start");
3769
3770 COMPILER2_PRESENT(DerivedPointerTable::clear());
3771
3772 // Please see comment in g1CollectedHeap.hpp and
3773 // G1CollectedHeap::ref_processing_init() to see how
3774 // reference processing currently works in G1.
3775
3776 // Enable discovery in the STW reference processor
3777 ref_processor_stw()->enable_discovery();
3778
3779 {
3780 // We want to temporarily turn off discovery by the
3781 // CM ref processor, if necessary, and turn it back on
3782 // on again later if we do. Using a scoped
3783 // NoRefDiscovery object will do this.
3784 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3785
3786 // Forget the current alloc region (we might even choose it to be part
3787 // of the collection set!).
3788 _allocator->release_mutator_alloc_region();
3789
3790 // We should call this after we retire the mutator alloc
3791 // region(s) so that all the ALLOC / RETIRE events are generated
3792 // before the start GC event.
3793 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3794
3795 // This timing is only used by the ergonomics to handle our pause target.
3796 // It is unclear why this should not include the full pause. We will
3797 // investigate this in CR 7178365.
3798 //
3799 // Preserving the old comment here if that helps the investigation:
3800 //
3801 // The elapsed time induced by the start time below deliberately elides
3802 // the possible verification above.
3803 double sample_start_time_sec = os::elapsedTime();
3804
3805 #if YOUNG_LIST_VERBOSE
3806 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3807 _young_list->print();
3808 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3809 #endif // YOUNG_LIST_VERBOSE
3810
3811 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3812
3813 double scan_wait_start = os::elapsedTime();
3814 // We have to wait until the CM threads finish scanning the
3815 // root regions as it's the only way to ensure that all the
3816 // objects on them have been correctly scanned before we start
3817 // moving them during the GC.
3818 bool waited = _cm->root_regions()->wait_until_scan_finished();
3819 double wait_time_ms = 0.0;
3820 if (waited) {
3821 double scan_wait_end = os::elapsedTime();
3822 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3823 }
3824 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3825
3826 #if YOUNG_LIST_VERBOSE
3827 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3828 _young_list->print();
3829 #endif // YOUNG_LIST_VERBOSE
3830
3831 if (g1_policy()->during_initial_mark_pause()) {
3832 concurrent_mark()->checkpointRootsInitialPre();
3833 }
3834
3835 #if YOUNG_LIST_VERBOSE
3836 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3837 _young_list->print();
3838 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3839 #endif // YOUNG_LIST_VERBOSE
3840
3841 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3842
3843 register_humongous_regions_with_cset();
3844
3845 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3846
3847 _cm->note_start_of_gc();
3848 // We should not verify the per-thread SATB buffers given that
3849 // we have not filtered them yet (we'll do so during the
3850 // GC). We also call this after finalize_cset() to
3851 // ensure that the CSet has been finalized.
3852 _cm->verify_no_cset_oops(true /* verify_stacks */,
3853 true /* verify_enqueued_buffers */,
3854 false /* verify_thread_buffers */,
3855 true /* verify_fingers */);
3856
3857 if (_hr_printer.is_active()) {
3858 HeapRegion* hr = g1_policy()->collection_set();
3859 while (hr != NULL) {
3860 _hr_printer.cset(hr);
3861 hr = hr->next_in_collection_set();
3862 }
3863 }
3864
3865 #ifdef ASSERT
3866 VerifyCSetClosure cl;
3867 collection_set_iterate(&cl);
3868 #endif // ASSERT
3869
3870 setup_surviving_young_words();
3871
3872 // Initialize the GC alloc regions.
3873 _allocator->init_gc_alloc_regions(evacuation_info);
3874
3875 // Actually do the work...
3876 evacuate_collection_set(evacuation_info);
3877
3878 // We do this to mainly verify the per-thread SATB buffers
3879 // (which have been filtered by now) since we didn't verify
3880 // them earlier. No point in re-checking the stacks / enqueued
3881 // buffers given that the CSet has not changed since last time
3882 // we checked.
3883 _cm->verify_no_cset_oops(false /* verify_stacks */,
3884 false /* verify_enqueued_buffers */,
3885 true /* verify_thread_buffers */,
3886 true /* verify_fingers */);
3887
3888 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3889
3890 eagerly_reclaim_humongous_regions();
3891
3892 g1_policy()->clear_collection_set();
3893
3894 cleanup_surviving_young_words();
3895
3896 // Start a new incremental collection set for the next pause.
3897 g1_policy()->start_incremental_cset_building();
3898
3899 clear_cset_fast_test();
3900
3901 _young_list->reset_sampled_info();
3902
3903 // Don't check the whole heap at this point as the
3904 // GC alloc regions from this pause have been tagged
3905 // as survivors and moved on to the survivor list.
3906 // Survivor regions will fail the !is_young() check.
3907 assert(check_young_list_empty(false /* check_heap */),
3908 "young list should be empty");
3909
3910 #if YOUNG_LIST_VERBOSE
3911 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3912 _young_list->print();
3913 #endif // YOUNG_LIST_VERBOSE
3914
3915 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3916 _young_list->first_survivor_region(),
3917 _young_list->last_survivor_region());
3918
3919 _young_list->reset_auxilary_lists();
3920
3921 if (evacuation_failed()) {
3922 _allocator->set_used(recalculate_used());
3923 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3924 for (uint i = 0; i < n_queues; i++) {
3925 if (_evacuation_failed_info_array[i].has_failed()) {
3926 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3927 }
3928 }
3929 } else {
3930 // The "used" of the the collection set have already been subtracted
3931 // when they were freed. Add in the bytes evacuated.
3932 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3933 }
3934
3935 if (g1_policy()->during_initial_mark_pause()) {
3936 // We have to do this before we notify the CM threads that
3937 // they can start working to make sure that all the
3938 // appropriate initialization is done on the CM object.
3939 concurrent_mark()->checkpointRootsInitialPost();
3940 set_marking_started();
3941 // Note that we don't actually trigger the CM thread at
3942 // this point. We do that later when we're sure that
3943 // the current thread has completed its logging output.
3944 }
3945
3946 allocate_dummy_regions();
3947
3948 #if YOUNG_LIST_VERBOSE
3949 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3950 _young_list->print();
3951 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3952 #endif // YOUNG_LIST_VERBOSE
3953
3954 _allocator->init_mutator_alloc_region();
3955
3956 {
3957 size_t expand_bytes = g1_policy()->expansion_amount();
3958 if (expand_bytes > 0) {
3959 size_t bytes_before = capacity();
3960 // No need for an ergo verbose message here,
3961 // expansion_amount() does this when it returns a value > 0.
3962 if (!expand(expand_bytes)) {
3963 // We failed to expand the heap. Cannot do anything about it.
3964 }
3965 }
3966 }
3967
3968 // We redo the verification but now wrt to the new CSet which
3969 // has just got initialized after the previous CSet was freed.
3970 _cm->verify_no_cset_oops(true /* verify_stacks */,
3971 true /* verify_enqueued_buffers */,
3972 true /* verify_thread_buffers */,
3973 true /* verify_fingers */);
3974 _cm->note_end_of_gc();
3975
3976 // This timing is only used by the ergonomics to handle our pause target.
3977 // It is unclear why this should not include the full pause. We will
3978 // investigate this in CR 7178365.
3979 double sample_end_time_sec = os::elapsedTime();
3980 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3981 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3982
3983 MemoryService::track_memory_usage();
3984
3985 // In prepare_for_verify() below we'll need to scan the deferred
3986 // update buffers to bring the RSets up-to-date if
3987 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3988 // the update buffers we'll probably need to scan cards on the
3989 // regions we just allocated to (i.e., the GC alloc
3990 // regions). However, during the last GC we called
3991 // set_saved_mark() on all the GC alloc regions, so card
3992 // scanning might skip the [saved_mark_word()...top()] area of
3993 // those regions (i.e., the area we allocated objects into
3994 // during the last GC). But it shouldn't. Given that
3995 // saved_mark_word() is conditional on whether the GC time stamp
3996 // on the region is current or not, by incrementing the GC time
3997 // stamp here we invalidate all the GC time stamps on all the
3998 // regions and saved_mark_word() will simply return top() for
3999 // all the regions. This is a nicer way of ensuring this rather
4000 // than iterating over the regions and fixing them. In fact, the
4001 // GC time stamp increment here also ensures that
4002 // saved_mark_word() will return top() between pauses, i.e.,
4003 // during concurrent refinement. So we don't need the
4004 // is_gc_active() check to decided which top to use when
4005 // scanning cards (see CR 7039627).
4006 increment_gc_time_stamp();
4007
4008 verify_after_gc();
4009 check_bitmaps("GC End");
4010
4011 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4012 ref_processor_stw()->verify_no_references_recorded();
4013
4014 // CM reference discovery will be re-enabled if necessary.
4015 }
4016
4017 // We should do this after we potentially expand the heap so
4018 // that all the COMMIT events are generated before the end GC
4019 // event, and after we retire the GC alloc regions so that all
4020 // RETIRE events are generated before the end GC event.
4021 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4022
4023 #ifdef TRACESPINNING
4024 ParallelTaskTerminator::print_termination_counts();
4025 #endif
4026
4027 gc_epilogue(false);
4028 }
4029
4030 // Print the remainder of the GC log output.
4031 log_gc_footer(os::elapsedTime() - pause_start_sec);
4032
4033 // It is not yet to safe to tell the concurrent mark to
4034 // start as we have some optional output below. We don't want the
4035 // output from the concurrent mark thread interfering with this
4036 // logging output either.
4037
4038 _hrm.verify_optional();
4039 verify_region_sets_optional();
4040
4041 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4042 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4043
4044 print_heap_after_gc();
4045 trace_heap_after_gc(_gc_tracer_stw);
4046
4047 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4048 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4049 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4050 // before any GC notifications are raised.
4051 g1mm()->update_sizes();
4052
4053 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4054 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4055 _gc_timer_stw->register_gc_end();
4056 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4057 }
4058 // It should now be safe to tell the concurrent mark thread to start
4059 // without its logging output interfering with the logging output
4060 // that came from the pause.
4061
4062 if (should_start_conc_mark) {
4063 // CAUTION: after the doConcurrentMark() call below,
4064 // the concurrent marking thread(s) could be running
4065 // concurrently with us. Make sure that anything after
4066 // this point does not assume that we are the only GC thread
4067 // running. Note: of course, the actual marking work will
4068 // not start until the safepoint itself is released in
4069 // SuspendibleThreadSet::desynchronize().
4070 doConcurrentMark();
4071 }
4072
4073 return true;
4074 }
4075
4076 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4077 _drain_in_progress = false;
4078 set_evac_failure_closure(cl);
4079 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4080 }
4081
4082 void G1CollectedHeap::finalize_for_evac_failure() {
4083 assert(_evac_failure_scan_stack != NULL &&
4084 _evac_failure_scan_stack->length() == 0,
4085 "Postcondition");
4086 assert(!_drain_in_progress, "Postcondition");
4087 delete _evac_failure_scan_stack;
4088 _evac_failure_scan_stack = NULL;
4089 }
4090
4091 void G1CollectedHeap::remove_self_forwarding_pointers() {
4092 double remove_self_forwards_start = os::elapsedTime();
4093
4094 set_par_threads();
4095 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4096 workers()->run_task(&rsfp_task);
4097 set_par_threads(0);
4098
4099 // Now restore saved marks, if any.
4100 assert(_objs_with_preserved_marks.size() ==
4101 _preserved_marks_of_objs.size(), "Both or none.");
4102 while (!_objs_with_preserved_marks.is_empty()) {
4103 oop obj = _objs_with_preserved_marks.pop();
4104 markOop m = _preserved_marks_of_objs.pop();
4105 obj->set_mark(m);
4106 }
4107 _objs_with_preserved_marks.clear(true);
4108 _preserved_marks_of_objs.clear(true);
4109
4110 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4111 }
4112
4113 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4114 _evac_failure_scan_stack->push(obj);
4115 }
4116
4117 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4118 assert(_evac_failure_scan_stack != NULL, "precondition");
4119
4120 while (_evac_failure_scan_stack->length() > 0) {
4121 oop obj = _evac_failure_scan_stack->pop();
4122 _evac_failure_closure->set_region(heap_region_containing(obj));
4123 obj->oop_iterate_backwards(_evac_failure_closure);
4124 }
4125 }
4126
4127 oop
4128 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4129 oop old) {
4130 assert(obj_in_cs(old),
4131 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4132 (HeapWord*) old));
4133 markOop m = old->mark();
4134 oop forward_ptr = old->forward_to_atomic(old);
4135 if (forward_ptr == NULL) {
4136 // Forward-to-self succeeded.
4137 assert(_par_scan_state != NULL, "par scan state");
4138 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4139 uint queue_num = _par_scan_state->queue_num();
4140
4141 _evacuation_failed = true;
4142 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4143 if (_evac_failure_closure != cl) {
4144 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4145 assert(!_drain_in_progress,
4146 "Should only be true while someone holds the lock.");
4147 // Set the global evac-failure closure to the current thread's.
4148 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4149 set_evac_failure_closure(cl);
4150 // Now do the common part.
4151 handle_evacuation_failure_common(old, m);
4152 // Reset to NULL.
4153 set_evac_failure_closure(NULL);
4154 } else {
4155 // The lock is already held, and this is recursive.
4156 assert(_drain_in_progress, "This should only be the recursive case.");
4157 handle_evacuation_failure_common(old, m);
4158 }
4159 return old;
4160 } else {
4161 // Forward-to-self failed. Either someone else managed to allocate
4162 // space for this object (old != forward_ptr) or they beat us in
4163 // self-forwarding it (old == forward_ptr).
4164 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4165 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4166 "should not be in the CSet",
4167 (HeapWord*) old, (HeapWord*) forward_ptr));
4168 return forward_ptr;
4169 }
4170 }
4171
4172 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4173 preserve_mark_if_necessary(old, m);
4174
4175 HeapRegion* r = heap_region_containing(old);
4176 if (!r->evacuation_failed()) {
4177 r->set_evacuation_failed(true);
4178 _hr_printer.evac_failure(r);
4179 }
4180
4181 push_on_evac_failure_scan_stack(old);
4182
4183 if (!_drain_in_progress) {
4184 // prevent recursion in copy_to_survivor_space()
4185 _drain_in_progress = true;
4186 drain_evac_failure_scan_stack();
4187 _drain_in_progress = false;
4188 }
4189 }
4190
4191 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4192 assert(evacuation_failed(), "Oversaving!");
4193 // We want to call the "for_promotion_failure" version only in the
4194 // case of a promotion failure.
4195 if (m->must_be_preserved_for_promotion_failure(obj)) {
4196 _objs_with_preserved_marks.push(obj);
4197 _preserved_marks_of_objs.push(m);
4198 }
4199 }
4200
4201 void G1ParCopyHelper::mark_object(oop obj) {
4202 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4203
4204 // We know that the object is not moving so it's safe to read its size.
4205 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4206 }
4207
4208 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4209 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4210 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4211 assert(from_obj != to_obj, "should not be self-forwarded");
4212
4213 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4214 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4215
4216 // The object might be in the process of being copied by another
4217 // worker so we cannot trust that its to-space image is
4218 // well-formed. So we have to read its size from its from-space
4219 // image which we know should not be changing.
4220 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4221 }
4222
4223 template <class T>
4224 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4225 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4226 _scanned_klass->record_modified_oops();
4227 }
4228 }
4229
4230 template <G1Barrier barrier, G1Mark do_mark_object>
4231 template <class T>
4232 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4233 T heap_oop = oopDesc::load_heap_oop(p);
4234
4235 if (oopDesc::is_null(heap_oop)) {
4236 return;
4237 }
4238
4239 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4240
4241 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4242
4243 const InCSetState state = _g1->in_cset_state(obj);
4244 if (state.is_in_cset()) {
4245 oop forwardee;
4246 markOop m = obj->mark();
4247 if (m->is_marked()) {
4248 forwardee = (oop) m->decode_pointer();
4249 } else {
4250 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4251 }
4252 assert(forwardee != NULL, "forwardee should not be NULL");
4253 oopDesc::encode_store_heap_oop(p, forwardee);
4254 if (do_mark_object != G1MarkNone && forwardee != obj) {
4255 // If the object is self-forwarded we don't need to explicitly
4256 // mark it, the evacuation failure protocol will do so.
4257 mark_forwarded_object(obj, forwardee);
4258 }
4259
4260 if (barrier == G1BarrierKlass) {
4261 do_klass_barrier(p, forwardee);
4262 }
4263 } else {
4264 if (state.is_humongous()) {
4265 _g1->set_humongous_is_live(obj);
4266 }
4267 // The object is not in collection set. If we're a root scanning
4268 // closure during an initial mark pause then attempt to mark the object.
4269 if (do_mark_object == G1MarkFromRoot) {
4270 mark_object(obj);
4271 }
4272 }
4273
4274 if (barrier == G1BarrierEvac) {
4275 _par_scan_state->update_rs(_from, p, _worker_id);
4276 }
4277 }
4278
4279 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4280 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4281
4282 class G1ParEvacuateFollowersClosure : public VoidClosure {
4283 protected:
4284 G1CollectedHeap* _g1h;
4285 G1ParScanThreadState* _par_scan_state;
4286 RefToScanQueueSet* _queues;
4287 ParallelTaskTerminator* _terminator;
4288
4289 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4290 RefToScanQueueSet* queues() { return _queues; }
4291 ParallelTaskTerminator* terminator() { return _terminator; }
4292
4293 public:
4294 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4295 G1ParScanThreadState* par_scan_state,
4296 RefToScanQueueSet* queues,
4297 ParallelTaskTerminator* terminator)
4298 : _g1h(g1h), _par_scan_state(par_scan_state),
4299 _queues(queues), _terminator(terminator) {}
4300
4301 void do_void();
4302
4303 private:
4304 inline bool offer_termination();
4305 };
4306
4307 bool G1ParEvacuateFollowersClosure::offer_termination() {
4308 G1ParScanThreadState* const pss = par_scan_state();
4309 pss->start_term_time();
4310 const bool res = terminator()->offer_termination();
4311 pss->end_term_time();
4312 return res;
4313 }
4314
4315 void G1ParEvacuateFollowersClosure::do_void() {
4316 G1ParScanThreadState* const pss = par_scan_state();
4317 pss->trim_queue();
4318 do {
4319 pss->steal_and_trim_queue(queues());
4320 } while (!offer_termination());
4321 }
4322
4323 class G1KlassScanClosure : public KlassClosure {
4324 G1ParCopyHelper* _closure;
4325 bool _process_only_dirty;
4326 int _count;
4327 public:
4328 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4329 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4330 void do_klass(Klass* klass) {
4331 // If the klass has not been dirtied we know that there's
4332 // no references into the young gen and we can skip it.
4333 if (!_process_only_dirty || klass->has_modified_oops()) {
4334 // Clean the klass since we're going to scavenge all the metadata.
4335 klass->clear_modified_oops();
4336
4337 // Tell the closure that this klass is the Klass to scavenge
4338 // and is the one to dirty if oops are left pointing into the young gen.
4339 _closure->set_scanned_klass(klass);
4340
4341 klass->oops_do(_closure);
4342
4343 _closure->set_scanned_klass(NULL);
4344 }
4345 _count++;
4346 }
4347 };
4348
4349 class G1ParTask : public AbstractGangTask {
4350 protected:
4351 G1CollectedHeap* _g1h;
4352 RefToScanQueueSet *_queues;
4353 G1RootProcessor* _root_processor;
4354 ParallelTaskTerminator _terminator;
4355 uint _n_workers;
4356
4357 Mutex _stats_lock;
4358 Mutex* stats_lock() { return &_stats_lock; }
4359
4360 public:
4361 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4362 : AbstractGangTask("G1 collection"),
4363 _g1h(g1h),
4364 _queues(task_queues),
4365 _root_processor(root_processor),
4366 _terminator(0, _queues),
4367 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4368 {}
4369
4370 RefToScanQueueSet* queues() { return _queues; }
4371
4372 RefToScanQueue *work_queue(int i) {
4373 return queues()->queue(i);
4374 }
4375
4376 ParallelTaskTerminator* terminator() { return &_terminator; }
4377
4378 virtual void set_for_termination(int active_workers) {
4379 _root_processor->set_num_workers(active_workers);
4380 terminator()->reset_for_reuse(active_workers);
4381 _n_workers = active_workers;
4382 }
4383
4384 // Helps out with CLD processing.
4385 //
4386 // During InitialMark we need to:
4387 // 1) Scavenge all CLDs for the young GC.
4388 // 2) Mark all objects directly reachable from strong CLDs.
4389 template <G1Mark do_mark_object>
4390 class G1CLDClosure : public CLDClosure {
4391 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4392 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4393 G1KlassScanClosure _klass_in_cld_closure;
4394 bool _claim;
4395
4396 public:
4397 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4398 bool only_young, bool claim)
4399 : _oop_closure(oop_closure),
4400 _oop_in_klass_closure(oop_closure->g1(),
4401 oop_closure->pss(),
4402 oop_closure->rp()),
4403 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4404 _claim(claim) {
4405
4406 }
4407
4408 void do_cld(ClassLoaderData* cld) {
4409 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4410 }
4411 };
4412
4413 void work(uint worker_id) {
4414 if (worker_id >= _n_workers) return; // no work needed this round
4415
4416 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4417
4418 {
4419 ResourceMark rm;
4420 HandleMark hm;
4421
4422 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4423
4424 G1ParScanThreadState pss(_g1h, worker_id, rp);
4425 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4426
4427 pss.set_evac_failure_closure(&evac_failure_cl);
4428
4429 bool only_young = _g1h->g1_policy()->gcs_are_young();
4430
4431 // Non-IM young GC.
4432 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4433 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4434 only_young, // Only process dirty klasses.
4435 false); // No need to claim CLDs.
4436 // IM young GC.
4437 // Strong roots closures.
4438 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4439 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4440 false, // Process all klasses.
4441 true); // Need to claim CLDs.
4442 // Weak roots closures.
4443 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4444 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4445 false, // Process all klasses.
4446 true); // Need to claim CLDs.
4447
4448 OopClosure* strong_root_cl;
4449 OopClosure* weak_root_cl;
4450 CLDClosure* strong_cld_cl;
4451 CLDClosure* weak_cld_cl;
4452
4453 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4454 // We also need to mark copied objects.
4455 strong_root_cl = &scan_mark_root_cl;
4456 strong_cld_cl = &scan_mark_cld_cl;
4457 if (ClassUnloadingWithConcurrentMark) {
4458 weak_root_cl = &scan_mark_weak_root_cl;
4459 weak_cld_cl = &scan_mark_weak_cld_cl;
4460 } else {
4461 weak_root_cl = &scan_mark_root_cl;
4462 weak_cld_cl = &scan_mark_cld_cl;
4463 }
4464 } else {
4465 strong_root_cl = &scan_only_root_cl;
4466 weak_root_cl = &scan_only_root_cl;
4467 strong_cld_cl = &scan_only_cld_cl;
4468 weak_cld_cl = &scan_only_cld_cl;
4469 }
4470
4471 pss.start_strong_roots();
4472
4473 _root_processor->evacuate_roots(strong_root_cl,
4474 weak_root_cl,
4475 strong_cld_cl,
4476 weak_cld_cl,
4477 worker_id);
4478
4479 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4480 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4481 weak_root_cl,
4482 worker_id);
4483 pss.end_strong_roots();
4484
4485 {
4486 double start = os::elapsedTime();
4487 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4488 evac.do_void();
4489 double elapsed_sec = os::elapsedTime() - start;
4490 double term_sec = pss.term_time();
4491 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4492 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4493 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4494 }
4495 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4496 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4497
4498 if (PrintTerminationStats) {
4499 MutexLocker x(stats_lock());
4500 pss.print_termination_stats(worker_id);
4501 }
4502
4503 assert(pss.queue_is_empty(), "should be empty");
4504
4505 // Close the inner scope so that the ResourceMark and HandleMark
4506 // destructors are executed here and are included as part of the
4507 // "GC Worker Time".
4508 }
4509 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4510 }
4511 };
4512
4513 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4514 private:
4515 BoolObjectClosure* _is_alive;
4516 int _initial_string_table_size;
4517 int _initial_symbol_table_size;
4518
4519 bool _process_strings;
4520 int _strings_processed;
4521 int _strings_removed;
4522
4523 bool _process_symbols;
4524 int _symbols_processed;
4525 int _symbols_removed;
4526
4527 public:
4528 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4529 AbstractGangTask("String/Symbol Unlinking"),
4530 _is_alive(is_alive),
4531 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4532 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4533
4534 _initial_string_table_size = StringTable::the_table()->table_size();
4535 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4536 if (process_strings) {
4537 StringTable::clear_parallel_claimed_index();
4538 }
4539 if (process_symbols) {
4540 SymbolTable::clear_parallel_claimed_index();
4541 }
4542 }
4543
4544 ~G1StringSymbolTableUnlinkTask() {
4545 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4546 err_msg("claim value %d after unlink less than initial string table size %d",
4547 StringTable::parallel_claimed_index(), _initial_string_table_size));
4548 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4549 err_msg("claim value %d after unlink less than initial symbol table size %d",
4550 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4551
4552 if (G1TraceStringSymbolTableScrubbing) {
4553 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4554 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4555 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4556 strings_processed(), strings_removed(),
4557 symbols_processed(), symbols_removed());
4558 }
4559 }
4560
4561 void work(uint worker_id) {
4562 int strings_processed = 0;
4563 int strings_removed = 0;
4564 int symbols_processed = 0;
4565 int symbols_removed = 0;
4566 if (_process_strings) {
4567 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4568 Atomic::add(strings_processed, &_strings_processed);
4569 Atomic::add(strings_removed, &_strings_removed);
4570 }
4571 if (_process_symbols) {
4572 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4573 Atomic::add(symbols_processed, &_symbols_processed);
4574 Atomic::add(symbols_removed, &_symbols_removed);
4575 }
4576 }
4577
4578 size_t strings_processed() const { return (size_t)_strings_processed; }
4579 size_t strings_removed() const { return (size_t)_strings_removed; }
4580
4581 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4582 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4583 };
4584
4585 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4586 private:
4587 static Monitor* _lock;
4588
4589 BoolObjectClosure* const _is_alive;
4590 const bool _unloading_occurred;
4591 const uint _num_workers;
4592
4593 // Variables used to claim nmethods.
4594 nmethod* _first_nmethod;
4595 volatile nmethod* _claimed_nmethod;
4596
4597 // The list of nmethods that need to be processed by the second pass.
4598 volatile nmethod* _postponed_list;
4599 volatile uint _num_entered_barrier;
4600
4601 public:
4602 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4603 _is_alive(is_alive),
4604 _unloading_occurred(unloading_occurred),
4605 _num_workers(num_workers),
4606 _first_nmethod(NULL),
4607 _claimed_nmethod(NULL),
4608 _postponed_list(NULL),
4609 _num_entered_barrier(0)
4610 {
4611 nmethod::increase_unloading_clock();
4612 // Get first alive nmethod
4613 NMethodIterator iter = NMethodIterator();
4614 if(iter.next_alive()) {
4615 _first_nmethod = iter.method();
4616 }
4617 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4618 }
4619
4620 ~G1CodeCacheUnloadingTask() {
4621 CodeCache::verify_clean_inline_caches();
4622
4623 CodeCache::set_needs_cache_clean(false);
4624 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4625
4626 CodeCache::verify_icholder_relocations();
4627 }
4628
4629 private:
4630 void add_to_postponed_list(nmethod* nm) {
4631 nmethod* old;
4632 do {
4633 old = (nmethod*)_postponed_list;
4634 nm->set_unloading_next(old);
4635 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4636 }
4637
4638 void clean_nmethod(nmethod* nm) {
4639 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4640
4641 if (postponed) {
4642 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4643 add_to_postponed_list(nm);
4644 }
4645
4646 // Mark that this thread has been cleaned/unloaded.
4647 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4648 nm->set_unloading_clock(nmethod::global_unloading_clock());
4649 }
4650
4651 void clean_nmethod_postponed(nmethod* nm) {
4652 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4653 }
4654
4655 static const int MaxClaimNmethods = 16;
4656
4657 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4658 nmethod* first;
4659 NMethodIterator last;
4660
4661 do {
4662 *num_claimed_nmethods = 0;
4663
4664 first = (nmethod*)_claimed_nmethod;
4665 last = NMethodIterator(first);
4666
4667 if (first != NULL) {
4668
4669 for (int i = 0; i < MaxClaimNmethods; i++) {
4670 if (!last.next_alive()) {
4671 break;
4672 }
4673 claimed_nmethods[i] = last.method();
4674 (*num_claimed_nmethods)++;
4675 }
4676 }
4677
4678 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4679 }
4680
4681 nmethod* claim_postponed_nmethod() {
4682 nmethod* claim;
4683 nmethod* next;
4684
4685 do {
4686 claim = (nmethod*)_postponed_list;
4687 if (claim == NULL) {
4688 return NULL;
4689 }
4690
4691 next = claim->unloading_next();
4692
4693 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4694
4695 return claim;
4696 }
4697
4698 public:
4699 // Mark that we're done with the first pass of nmethod cleaning.
4700 void barrier_mark(uint worker_id) {
4701 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4702 _num_entered_barrier++;
4703 if (_num_entered_barrier == _num_workers) {
4704 ml.notify_all();
4705 }
4706 }
4707
4708 // See if we have to wait for the other workers to
4709 // finish their first-pass nmethod cleaning work.
4710 void barrier_wait(uint worker_id) {
4711 if (_num_entered_barrier < _num_workers) {
4712 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4713 while (_num_entered_barrier < _num_workers) {
4714 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4715 }
4716 }
4717 }
4718
4719 // Cleaning and unloading of nmethods. Some work has to be postponed
4720 // to the second pass, when we know which nmethods survive.
4721 void work_first_pass(uint worker_id) {
4722 // The first nmethods is claimed by the first worker.
4723 if (worker_id == 0 && _first_nmethod != NULL) {
4724 clean_nmethod(_first_nmethod);
4725 _first_nmethod = NULL;
4726 }
4727
4728 int num_claimed_nmethods;
4729 nmethod* claimed_nmethods[MaxClaimNmethods];
4730
4731 while (true) {
4732 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4733
4734 if (num_claimed_nmethods == 0) {
4735 break;
4736 }
4737
4738 for (int i = 0; i < num_claimed_nmethods; i++) {
4739 clean_nmethod(claimed_nmethods[i]);
4740 }
4741 }
4742
4743 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4744 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4745 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4746 }
4747
4748 void work_second_pass(uint worker_id) {
4749 nmethod* nm;
4750 // Take care of postponed nmethods.
4751 while ((nm = claim_postponed_nmethod()) != NULL) {
4752 clean_nmethod_postponed(nm);
4753 }
4754 }
4755 };
4756
4757 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4758
4759 class G1KlassCleaningTask : public StackObj {
4760 BoolObjectClosure* _is_alive;
4761 volatile jint _clean_klass_tree_claimed;
4762 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4763
4764 public:
4765 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4766 _is_alive(is_alive),
4767 _clean_klass_tree_claimed(0),
4768 _klass_iterator() {
4769 }
4770
4771 private:
4772 bool claim_clean_klass_tree_task() {
4773 if (_clean_klass_tree_claimed) {
4774 return false;
4775 }
4776
4777 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4778 }
4779
4780 InstanceKlass* claim_next_klass() {
4781 Klass* klass;
4782 do {
4783 klass =_klass_iterator.next_klass();
4784 } while (klass != NULL && !klass->oop_is_instance());
4785
4786 return (InstanceKlass*)klass;
4787 }
4788
4789 public:
4790
4791 void clean_klass(InstanceKlass* ik) {
4792 ik->clean_implementors_list(_is_alive);
4793 ik->clean_method_data(_is_alive);
4794
4795 // G1 specific cleanup work that has
4796 // been moved here to be done in parallel.
4797 ik->clean_dependent_nmethods();
4798 if (JvmtiExport::has_redefined_a_class()) {
4799 InstanceKlass::purge_previous_versions(ik);
4800 }
4801 }
4802
4803 void work() {
4804 ResourceMark rm;
4805
4806 // One worker will clean the subklass/sibling klass tree.
4807 if (claim_clean_klass_tree_task()) {
4808 Klass::clean_subklass_tree(_is_alive);
4809 }
4810
4811 // All workers will help cleaning the classes,
4812 InstanceKlass* klass;
4813 while ((klass = claim_next_klass()) != NULL) {
4814 clean_klass(klass);
4815 }
4816 }
4817 };
4818
4819 // To minimize the remark pause times, the tasks below are done in parallel.
4820 class G1ParallelCleaningTask : public AbstractGangTask {
4821 private:
4822 G1StringSymbolTableUnlinkTask _string_symbol_task;
4823 G1CodeCacheUnloadingTask _code_cache_task;
4824 G1KlassCleaningTask _klass_cleaning_task;
4825
4826 public:
4827 // The constructor is run in the VMThread.
4828 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4829 AbstractGangTask("Parallel Cleaning"),
4830 _string_symbol_task(is_alive, process_strings, process_symbols),
4831 _code_cache_task(num_workers, is_alive, unloading_occurred),
4832 _klass_cleaning_task(is_alive) {
4833 }
4834
4835 void pre_work_verification() {
4836 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4837 }
4838
4839 void post_work_verification() {
4840 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4841 }
4842
4843 // The parallel work done by all worker threads.
4844 void work(uint worker_id) {
4845 pre_work_verification();
4846
4847 // Do first pass of code cache cleaning.
4848 _code_cache_task.work_first_pass(worker_id);
4849
4850 // Let the threads mark that the first pass is done.
4851 _code_cache_task.barrier_mark(worker_id);
4852
4853 // Clean the Strings and Symbols.
4854 _string_symbol_task.work(worker_id);
4855
4856 // Wait for all workers to finish the first code cache cleaning pass.
4857 _code_cache_task.barrier_wait(worker_id);
4858
4859 // Do the second code cache cleaning work, which realize on
4860 // the liveness information gathered during the first pass.
4861 _code_cache_task.work_second_pass(worker_id);
4862
4863 // Clean all klasses that were not unloaded.
4864 _klass_cleaning_task.work();
4865
4866 post_work_verification();
4867 }
4868 };
4869
4870
4871 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4872 bool process_strings,
4873 bool process_symbols,
4874 bool class_unloading_occurred) {
4875 uint n_workers = workers()->active_workers();
4876
4877 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4878 n_workers, class_unloading_occurred);
4879 set_par_threads(n_workers);
4880 workers()->run_task(&g1_unlink_task);
4881 set_par_threads(0);
4882 }
4883
4884 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4885 bool process_strings, bool process_symbols) {
4886 {
4887 uint n_workers = _g1h->workers()->active_workers();
4888 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4889 set_par_threads(n_workers);
4890 workers()->run_task(&g1_unlink_task);
4891 set_par_threads(0);
4892 }
4893
4894 if (G1StringDedup::is_enabled()) {
4895 G1StringDedup::unlink(is_alive);
4896 }
4897 }
4898
4899 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4900 private:
4901 DirtyCardQueueSet* _queue;
4902 public:
4903 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4904
4905 virtual void work(uint worker_id) {
4906 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4907 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4908
4909 RedirtyLoggedCardTableEntryClosure cl;
4910 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4911
4912 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4913 }
4914 };
4915
4916 void G1CollectedHeap::redirty_logged_cards() {
4917 double redirty_logged_cards_start = os::elapsedTime();
4918
4919 uint n_workers = _g1h->workers()->active_workers();
4920
4921 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4922 dirty_card_queue_set().reset_for_par_iteration();
4923 set_par_threads(n_workers);
4924 workers()->run_task(&redirty_task);
4925 set_par_threads(0);
4926
4927 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4928 dcq.merge_bufferlists(&dirty_card_queue_set());
4929 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4930
4931 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4932 }
4933
4934 // Weak Reference Processing support
4935
4936 // An always "is_alive" closure that is used to preserve referents.
4937 // If the object is non-null then it's alive. Used in the preservation
4938 // of referent objects that are pointed to by reference objects
4939 // discovered by the CM ref processor.
4940 class G1AlwaysAliveClosure: public BoolObjectClosure {
4941 G1CollectedHeap* _g1;
4942 public:
4943 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4944 bool do_object_b(oop p) {
4945 if (p != NULL) {
4946 return true;
4947 }
4948 return false;
4949 }
4950 };
4951
4952 bool G1STWIsAliveClosure::do_object_b(oop p) {
4953 // An object is reachable if it is outside the collection set,
4954 // or is inside and copied.
4955 return !_g1->obj_in_cs(p) || p->is_forwarded();
4956 }
4957
4958 // Non Copying Keep Alive closure
4959 class G1KeepAliveClosure: public OopClosure {
4960 G1CollectedHeap* _g1;
4961 public:
4962 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4963 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4964 void do_oop(oop* p) {
4965 oop obj = *p;
4966 assert(obj != NULL, "the caller should have filtered out NULL values");
4967
4968 const InCSetState cset_state = _g1->in_cset_state(obj);
4969 if (!cset_state.is_in_cset_or_humongous()) {
4970 return;
4971 }
4972 if (cset_state.is_in_cset()) {
4973 assert( obj->is_forwarded(), "invariant" );
4974 *p = obj->forwardee();
4975 } else {
4976 assert(!obj->is_forwarded(), "invariant" );
4977 assert(cset_state.is_humongous(),
4978 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4979 _g1->set_humongous_is_live(obj);
4980 }
4981 }
4982 };
4983
4984 // Copying Keep Alive closure - can be called from both
4985 // serial and parallel code as long as different worker
4986 // threads utilize different G1ParScanThreadState instances
4987 // and different queues.
4988
4989 class G1CopyingKeepAliveClosure: public OopClosure {
4990 G1CollectedHeap* _g1h;
4991 OopClosure* _copy_non_heap_obj_cl;
4992 G1ParScanThreadState* _par_scan_state;
4993
4994 public:
4995 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4996 OopClosure* non_heap_obj_cl,
4997 G1ParScanThreadState* pss):
4998 _g1h(g1h),
4999 _copy_non_heap_obj_cl(non_heap_obj_cl),
5000 _par_scan_state(pss)
5001 {}
5002
5003 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5004 virtual void do_oop( oop* p) { do_oop_work(p); }
5005
5006 template <class T> void do_oop_work(T* p) {
5007 oop obj = oopDesc::load_decode_heap_oop(p);
5008
5009 if (_g1h->is_in_cset_or_humongous(obj)) {
5010 // If the referent object has been forwarded (either copied
5011 // to a new location or to itself in the event of an
5012 // evacuation failure) then we need to update the reference
5013 // field and, if both reference and referent are in the G1
5014 // heap, update the RSet for the referent.
5015 //
5016 // If the referent has not been forwarded then we have to keep
5017 // it alive by policy. Therefore we have copy the referent.
5018 //
5019 // If the reference field is in the G1 heap then we can push
5020 // on the PSS queue. When the queue is drained (after each
5021 // phase of reference processing) the object and it's followers
5022 // will be copied, the reference field set to point to the
5023 // new location, and the RSet updated. Otherwise we need to
5024 // use the the non-heap or metadata closures directly to copy
5025 // the referent object and update the pointer, while avoiding
5026 // updating the RSet.
5027
5028 if (_g1h->is_in_g1_reserved(p)) {
5029 _par_scan_state->push_on_queue(p);
5030 } else {
5031 assert(!Metaspace::contains((const void*)p),
5032 err_msg("Unexpectedly found a pointer from metadata: "
5033 PTR_FORMAT, p));
5034 _copy_non_heap_obj_cl->do_oop(p);
5035 }
5036 }
5037 }
5038 };
5039
5040 // Serial drain queue closure. Called as the 'complete_gc'
5041 // closure for each discovered list in some of the
5042 // reference processing phases.
5043
5044 class G1STWDrainQueueClosure: public VoidClosure {
5045 protected:
5046 G1CollectedHeap* _g1h;
5047 G1ParScanThreadState* _par_scan_state;
5048
5049 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5050
5051 public:
5052 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5053 _g1h(g1h),
5054 _par_scan_state(pss)
5055 { }
5056
5057 void do_void() {
5058 G1ParScanThreadState* const pss = par_scan_state();
5059 pss->trim_queue();
5060 }
5061 };
5062
5063 // Parallel Reference Processing closures
5064
5065 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5066 // processing during G1 evacuation pauses.
5067
5068 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5069 private:
5070 G1CollectedHeap* _g1h;
5071 RefToScanQueueSet* _queues;
5072 FlexibleWorkGang* _workers;
5073 int _active_workers;
5074
5075 public:
5076 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5077 FlexibleWorkGang* workers,
5078 RefToScanQueueSet *task_queues,
5079 int n_workers) :
5080 _g1h(g1h),
5081 _queues(task_queues),
5082 _workers(workers),
5083 _active_workers(n_workers)
5084 {
5085 assert(n_workers > 0, "shouldn't call this otherwise");
5086 }
5087
5088 // Executes the given task using concurrent marking worker threads.
5089 virtual void execute(ProcessTask& task);
5090 virtual void execute(EnqueueTask& task);
5091 };
5092
5093 // Gang task for possibly parallel reference processing
5094
5095 class G1STWRefProcTaskProxy: public AbstractGangTask {
5096 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5097 ProcessTask& _proc_task;
5098 G1CollectedHeap* _g1h;
5099 RefToScanQueueSet *_task_queues;
5100 ParallelTaskTerminator* _terminator;
5101
5102 public:
5103 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5104 G1CollectedHeap* g1h,
5105 RefToScanQueueSet *task_queues,
5106 ParallelTaskTerminator* terminator) :
5107 AbstractGangTask("Process reference objects in parallel"),
5108 _proc_task(proc_task),
5109 _g1h(g1h),
5110 _task_queues(task_queues),
5111 _terminator(terminator)
5112 {}
5113
5114 virtual void work(uint worker_id) {
5115 // The reference processing task executed by a single worker.
5116 ResourceMark rm;
5117 HandleMark hm;
5118
5119 G1STWIsAliveClosure is_alive(_g1h);
5120
5121 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5122 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5123
5124 pss.set_evac_failure_closure(&evac_failure_cl);
5125
5126 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5127
5128 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5129
5130 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5131
5132 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5133 // We also need to mark copied objects.
5134 copy_non_heap_cl = ©_mark_non_heap_cl;
5135 }
5136
5137 // Keep alive closure.
5138 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5139
5140 // Complete GC closure
5141 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5142
5143 // Call the reference processing task's work routine.
5144 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5145
5146 // Note we cannot assert that the refs array is empty here as not all
5147 // of the processing tasks (specifically phase2 - pp2_work) execute
5148 // the complete_gc closure (which ordinarily would drain the queue) so
5149 // the queue may not be empty.
5150 }
5151 };
5152
5153 // Driver routine for parallel reference processing.
5154 // Creates an instance of the ref processing gang
5155 // task and has the worker threads execute it.
5156 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5157 assert(_workers != NULL, "Need parallel worker threads.");
5158
5159 ParallelTaskTerminator terminator(_active_workers, _queues);
5160 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5161
5162 _g1h->set_par_threads(_active_workers);
5163 _workers->run_task(&proc_task_proxy);
5164 _g1h->set_par_threads(0);
5165 }
5166
5167 // Gang task for parallel reference enqueueing.
5168
5169 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5170 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5171 EnqueueTask& _enq_task;
5172
5173 public:
5174 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5175 AbstractGangTask("Enqueue reference objects in parallel"),
5176 _enq_task(enq_task)
5177 { }
5178
5179 virtual void work(uint worker_id) {
5180 _enq_task.work(worker_id);
5181 }
5182 };
5183
5184 // Driver routine for parallel reference enqueueing.
5185 // Creates an instance of the ref enqueueing gang
5186 // task and has the worker threads execute it.
5187
5188 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5189 assert(_workers != NULL, "Need parallel worker threads.");
5190
5191 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5192
5193 _g1h->set_par_threads(_active_workers);
5194 _workers->run_task(&enq_task_proxy);
5195 _g1h->set_par_threads(0);
5196 }
5197
5198 // End of weak reference support closures
5199
5200 // Abstract task used to preserve (i.e. copy) any referent objects
5201 // that are in the collection set and are pointed to by reference
5202 // objects discovered by the CM ref processor.
5203
5204 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5205 protected:
5206 G1CollectedHeap* _g1h;
5207 RefToScanQueueSet *_queues;
5208 ParallelTaskTerminator _terminator;
5209 uint _n_workers;
5210
5211 public:
5212 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5213 AbstractGangTask("ParPreserveCMReferents"),
5214 _g1h(g1h),
5215 _queues(task_queues),
5216 _terminator(workers, _queues),
5217 _n_workers(workers)
5218 { }
5219
5220 void work(uint worker_id) {
5221 ResourceMark rm;
5222 HandleMark hm;
5223
5224 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5225 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5226
5227 pss.set_evac_failure_closure(&evac_failure_cl);
5228
5229 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5230
5231 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5232
5233 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5234
5235 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5236
5237 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5238 // We also need to mark copied objects.
5239 copy_non_heap_cl = ©_mark_non_heap_cl;
5240 }
5241
5242 // Is alive closure
5243 G1AlwaysAliveClosure always_alive(_g1h);
5244
5245 // Copying keep alive closure. Applied to referent objects that need
5246 // to be copied.
5247 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5248
5249 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5250
5251 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5252 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5253
5254 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5255 // So this must be true - but assert just in case someone decides to
5256 // change the worker ids.
5257 assert(0 <= worker_id && worker_id < limit, "sanity");
5258 assert(!rp->discovery_is_atomic(), "check this code");
5259
5260 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5261 for (uint idx = worker_id; idx < limit; idx += stride) {
5262 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5263
5264 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5265 while (iter.has_next()) {
5266 // Since discovery is not atomic for the CM ref processor, we
5267 // can see some null referent objects.
5268 iter.load_ptrs(DEBUG_ONLY(true));
5269 oop ref = iter.obj();
5270
5271 // This will filter nulls.
5272 if (iter.is_referent_alive()) {
5273 iter.make_referent_alive();
5274 }
5275 iter.move_to_next();
5276 }
5277 }
5278
5279 // Drain the queue - which may cause stealing
5280 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5281 drain_queue.do_void();
5282 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5283 assert(pss.queue_is_empty(), "should be");
5284 }
5285 };
5286
5287 // Weak Reference processing during an evacuation pause (part 1).
5288 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5289 double ref_proc_start = os::elapsedTime();
5290
5291 ReferenceProcessor* rp = _ref_processor_stw;
5292 assert(rp->discovery_enabled(), "should have been enabled");
5293
5294 // Any reference objects, in the collection set, that were 'discovered'
5295 // by the CM ref processor should have already been copied (either by
5296 // applying the external root copy closure to the discovered lists, or
5297 // by following an RSet entry).
5298 //
5299 // But some of the referents, that are in the collection set, that these
5300 // reference objects point to may not have been copied: the STW ref
5301 // processor would have seen that the reference object had already
5302 // been 'discovered' and would have skipped discovering the reference,
5303 // but would not have treated the reference object as a regular oop.
5304 // As a result the copy closure would not have been applied to the
5305 // referent object.
5306 //
5307 // We need to explicitly copy these referent objects - the references
5308 // will be processed at the end of remarking.
5309 //
5310 // We also need to do this copying before we process the reference
5311 // objects discovered by the STW ref processor in case one of these
5312 // referents points to another object which is also referenced by an
5313 // object discovered by the STW ref processor.
5314
5315 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5316
5317 set_par_threads(no_of_gc_workers);
5318 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5319 no_of_gc_workers,
5320 _task_queues);
5321
5322 workers()->run_task(&keep_cm_referents);
5323
5324 set_par_threads(0);
5325
5326 // Closure to test whether a referent is alive.
5327 G1STWIsAliveClosure is_alive(this);
5328
5329 // Even when parallel reference processing is enabled, the processing
5330 // of JNI refs is serial and performed serially by the current thread
5331 // rather than by a worker. The following PSS will be used for processing
5332 // JNI refs.
5333
5334 // Use only a single queue for this PSS.
5335 G1ParScanThreadState pss(this, 0, NULL);
5336
5337 // We do not embed a reference processor in the copying/scanning
5338 // closures while we're actually processing the discovered
5339 // reference objects.
5340 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5341
5342 pss.set_evac_failure_closure(&evac_failure_cl);
5343
5344 assert(pss.queue_is_empty(), "pre-condition");
5345
5346 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5347
5348 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5349
5350 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5351
5352 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5353 // We also need to mark copied objects.
5354 copy_non_heap_cl = ©_mark_non_heap_cl;
5355 }
5356
5357 // Keep alive closure.
5358 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5359
5360 // Serial Complete GC closure
5361 G1STWDrainQueueClosure drain_queue(this, &pss);
5362
5363 // Setup the soft refs policy...
5364 rp->setup_policy(false);
5365
5366 ReferenceProcessorStats stats;
5367 if (!rp->processing_is_mt()) {
5368 // Serial reference processing...
5369 stats = rp->process_discovered_references(&is_alive,
5370 &keep_alive,
5371 &drain_queue,
5372 NULL,
5373 _gc_timer_stw,
5374 _gc_tracer_stw->gc_id());
5375 } else {
5376 // Parallel reference processing
5377 assert(rp->num_q() == no_of_gc_workers, "sanity");
5378 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5379
5380 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5381 stats = rp->process_discovered_references(&is_alive,
5382 &keep_alive,
5383 &drain_queue,
5384 &par_task_executor,
5385 _gc_timer_stw,
5386 _gc_tracer_stw->gc_id());
5387 }
5388
5389 _gc_tracer_stw->report_gc_reference_stats(stats);
5390
5391 // We have completed copying any necessary live referent objects.
5392 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5393
5394 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5395 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5396 }
5397
5398 // Weak Reference processing during an evacuation pause (part 2).
5399 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5400 double ref_enq_start = os::elapsedTime();
5401
5402 ReferenceProcessor* rp = _ref_processor_stw;
5403 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5404
5405 // Now enqueue any remaining on the discovered lists on to
5406 // the pending list.
5407 if (!rp->processing_is_mt()) {
5408 // Serial reference processing...
5409 rp->enqueue_discovered_references();
5410 } else {
5411 // Parallel reference enqueueing
5412
5413 assert(no_of_gc_workers == workers()->active_workers(),
5414 "Need to reset active workers");
5415 assert(rp->num_q() == no_of_gc_workers, "sanity");
5416 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5417
5418 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5419 rp->enqueue_discovered_references(&par_task_executor);
5420 }
5421
5422 rp->verify_no_references_recorded();
5423 assert(!rp->discovery_enabled(), "should have been disabled");
5424
5425 // FIXME
5426 // CM's reference processing also cleans up the string and symbol tables.
5427 // Should we do that here also? We could, but it is a serial operation
5428 // and could significantly increase the pause time.
5429
5430 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5431 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5432 }
5433
5434 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5435 _expand_heap_after_alloc_failure = true;
5436 _evacuation_failed = false;
5437
5438 // Should G1EvacuationFailureALot be in effect for this GC?
5439 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5440
5441 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5442
5443 // Disable the hot card cache.
5444 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5445 hot_card_cache->reset_hot_cache_claimed_index();
5446 hot_card_cache->set_use_cache(false);
5447
5448 uint n_workers;
5449 n_workers =
5450 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5451 workers()->active_workers(),
5452 Threads::number_of_non_daemon_threads());
5453 assert(UseDynamicNumberOfGCThreads ||
5454 n_workers == workers()->total_workers(),
5455 "If not dynamic should be using all the workers");
5456 workers()->set_active_workers(n_workers);
5457 set_par_threads(n_workers);
5458
5459
5460 init_for_evac_failure(NULL);
5461
5462 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5463 double start_par_time_sec = os::elapsedTime();
5464 double end_par_time_sec;
5465
5466 {
5467 const bool during_im = g1_policy()->during_initial_mark_pause();
5468 const bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
5469
5470 G1RootProcessor root_processor(this, trace_metadata);
5471 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5472 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5473 if (during_im) {
5474 ClassLoaderDataGraph::clear_claimed_marks();
5475 }
5476
5477 // The individual threads will set their evac-failure closures.
5478 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5479 // These tasks use ShareHeap::_process_strong_tasks
5480 assert(UseDynamicNumberOfGCThreads ||
5481 workers()->active_workers() == workers()->total_workers(),
5482 "If not dynamic should be using all the workers");
5483 workers()->run_task(&g1_par_task);
5484 end_par_time_sec = os::elapsedTime();
5485
5486 // Closing the inner scope will execute the destructor
5487 // for the G1RootProcessor object. We record the current
5488 // elapsed time before closing the scope so that time
5489 // taken for the destructor is NOT included in the
5490 // reported parallel time.
5491 }
5492
5493 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5494
5495 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5496 phase_times->record_par_time(par_time_ms);
5497
5498 double code_root_fixup_time_ms =
5499 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5500 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5501
5502 set_par_threads(0);
5503
5504 // Process any discovered reference objects - we have
5505 // to do this _before_ we retire the GC alloc regions
5506 // as we may have to copy some 'reachable' referent
5507 // objects (and their reachable sub-graphs) that were
5508 // not copied during the pause.
5509 process_discovered_references(n_workers);
5510
5511 if (G1StringDedup::is_enabled()) {
5512 double fixup_start = os::elapsedTime();
5513
5514 G1STWIsAliveClosure is_alive(this);
5515 G1KeepAliveClosure keep_alive(this);
5516 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5517
5518 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5519 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5520 }
5521
5522 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5523 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5524
5525 // Reset and re-enable the hot card cache.
5526 // Note the counts for the cards in the regions in the
5527 // collection set are reset when the collection set is freed.
5528 hot_card_cache->reset_hot_cache();
5529 hot_card_cache->set_use_cache(true);
5530
5531 purge_code_root_memory();
5532
5533 finalize_for_evac_failure();
5534
5535 if (evacuation_failed()) {
5536 remove_self_forwarding_pointers();
5537
5538 // Reset the G1EvacuationFailureALot counters and flags
5539 // Note: the values are reset only when an actual
5540 // evacuation failure occurs.
5541 NOT_PRODUCT(reset_evacuation_should_fail();)
5542 }
5543
5544 // Enqueue any remaining references remaining on the STW
5545 // reference processor's discovered lists. We need to do
5546 // this after the card table is cleaned (and verified) as
5547 // the act of enqueueing entries on to the pending list
5548 // will log these updates (and dirty their associated
5549 // cards). We need these updates logged to update any
5550 // RSets.
5551 enqueue_discovered_references(n_workers);
5552
5553 redirty_logged_cards();
5554 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5555 }
5556
5557 void G1CollectedHeap::free_region(HeapRegion* hr,
5558 FreeRegionList* free_list,
5559 bool par,
5560 bool locked) {
5561 assert(!hr->is_free(), "the region should not be free");
5562 assert(!hr->is_empty(), "the region should not be empty");
5563 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5564 assert(free_list != NULL, "pre-condition");
5565
5566 if (G1VerifyBitmaps) {
5567 MemRegion mr(hr->bottom(), hr->end());
5568 concurrent_mark()->clearRangePrevBitmap(mr);
5569 }
5570
5571 // Clear the card counts for this region.
5572 // Note: we only need to do this if the region is not young
5573 // (since we don't refine cards in young regions).
5574 if (!hr->is_young()) {
5575 _cg1r->hot_card_cache()->reset_card_counts(hr);
5576 }
5577 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5578 free_list->add_ordered(hr);
5579 }
5580
5581 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5582 FreeRegionList* free_list,
5583 bool par) {
5584 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5585 assert(free_list != NULL, "pre-condition");
5586
5587 size_t hr_capacity = hr->capacity();
5588 // We need to read this before we make the region non-humongous,
5589 // otherwise the information will be gone.
5590 uint last_index = hr->last_hc_index();
5591 hr->clear_humongous();
5592 free_region(hr, free_list, par);
5593
5594 uint i = hr->hrm_index() + 1;
5595 while (i < last_index) {
5596 HeapRegion* curr_hr = region_at(i);
5597 assert(curr_hr->is_continues_humongous(), "invariant");
5598 curr_hr->clear_humongous();
5599 free_region(curr_hr, free_list, par);
5600 i += 1;
5601 }
5602 }
5603
5604 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5605 const HeapRegionSetCount& humongous_regions_removed) {
5606 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5607 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5608 _old_set.bulk_remove(old_regions_removed);
5609 _humongous_set.bulk_remove(humongous_regions_removed);
5610 }
5611
5612 }
5613
5614 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5615 assert(list != NULL, "list can't be null");
5616 if (!list->is_empty()) {
5617 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5618 _hrm.insert_list_into_free_list(list);
5619 }
5620 }
5621
5622 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5623 _allocator->decrease_used(bytes);
5624 }
5625
5626 class G1ParCleanupCTTask : public AbstractGangTask {
5627 G1SATBCardTableModRefBS* _ct_bs;
5628 G1CollectedHeap* _g1h;
5629 HeapRegion* volatile _su_head;
5630 public:
5631 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5632 G1CollectedHeap* g1h) :
5633 AbstractGangTask("G1 Par Cleanup CT Task"),
5634 _ct_bs(ct_bs), _g1h(g1h) { }
5635
5636 void work(uint worker_id) {
5637 HeapRegion* r;
5638 while (r = _g1h->pop_dirty_cards_region()) {
5639 clear_cards(r);
5640 }
5641 }
5642
5643 void clear_cards(HeapRegion* r) {
5644 // Cards of the survivors should have already been dirtied.
5645 if (!r->is_survivor()) {
5646 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5647 }
5648 }
5649 };
5650
5651 #ifndef PRODUCT
5652 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5653 G1CollectedHeap* _g1h;
5654 G1SATBCardTableModRefBS* _ct_bs;
5655 public:
5656 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5657 : _g1h(g1h), _ct_bs(ct_bs) { }
5658 virtual bool doHeapRegion(HeapRegion* r) {
5659 if (r->is_survivor()) {
5660 _g1h->verify_dirty_region(r);
5661 } else {
5662 _g1h->verify_not_dirty_region(r);
5663 }
5664 return false;
5665 }
5666 };
5667
5668 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5669 // All of the region should be clean.
5670 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5671 MemRegion mr(hr->bottom(), hr->end());
5672 ct_bs->verify_not_dirty_region(mr);
5673 }
5674
5675 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5676 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5677 // dirty allocated blocks as they allocate them. The thread that
5678 // retires each region and replaces it with a new one will do a
5679 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5680 // not dirty that area (one less thing to have to do while holding
5681 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5682 // is dirty.
5683 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5684 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5685 if (hr->is_young()) {
5686 ct_bs->verify_g1_young_region(mr);
5687 } else {
5688 ct_bs->verify_dirty_region(mr);
5689 }
5690 }
5691
5692 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5693 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5694 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5695 verify_dirty_region(hr);
5696 }
5697 }
5698
5699 void G1CollectedHeap::verify_dirty_young_regions() {
5700 verify_dirty_young_list(_young_list->first_region());
5701 }
5702
5703 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5704 HeapWord* tams, HeapWord* end) {
5705 guarantee(tams <= end,
5706 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5707 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5708 if (result < end) {
5709 gclog_or_tty->cr();
5710 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5711 bitmap_name, result);
5712 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5713 bitmap_name, tams, end);
5714 return false;
5715 }
5716 return true;
5717 }
5718
5719 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5720 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5721 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5722
5723 HeapWord* bottom = hr->bottom();
5724 HeapWord* ptams = hr->prev_top_at_mark_start();
5725 HeapWord* ntams = hr->next_top_at_mark_start();
5726 HeapWord* end = hr->end();
5727
5728 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5729
5730 bool res_n = true;
5731 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5732 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5733 // if we happen to be in that state.
5734 if (mark_in_progress() || !_cmThread->in_progress()) {
5735 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5736 }
5737 if (!res_p || !res_n) {
5738 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5739 HR_FORMAT_PARAMS(hr));
5740 gclog_or_tty->print_cr("#### Caller: %s", caller);
5741 return false;
5742 }
5743 return true;
5744 }
5745
5746 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5747 if (!G1VerifyBitmaps) return;
5748
5749 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5750 }
5751
5752 class G1VerifyBitmapClosure : public HeapRegionClosure {
5753 private:
5754 const char* _caller;
5755 G1CollectedHeap* _g1h;
5756 bool _failures;
5757
5758 public:
5759 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5760 _caller(caller), _g1h(g1h), _failures(false) { }
5761
5762 bool failures() { return _failures; }
5763
5764 virtual bool doHeapRegion(HeapRegion* hr) {
5765 if (hr->is_continues_humongous()) return false;
5766
5767 bool result = _g1h->verify_bitmaps(_caller, hr);
5768 if (!result) {
5769 _failures = true;
5770 }
5771 return false;
5772 }
5773 };
5774
5775 void G1CollectedHeap::check_bitmaps(const char* caller) {
5776 if (!G1VerifyBitmaps) return;
5777
5778 G1VerifyBitmapClosure cl(caller, this);
5779 heap_region_iterate(&cl);
5780 guarantee(!cl.failures(), "bitmap verification");
5781 }
5782
5783 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5784 private:
5785 bool _failures;
5786 public:
5787 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5788
5789 virtual bool doHeapRegion(HeapRegion* hr) {
5790 uint i = hr->hrm_index();
5791 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5792 if (hr->is_humongous()) {
5793 if (hr->in_collection_set()) {
5794 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5795 _failures = true;
5796 return true;
5797 }
5798 if (cset_state.is_in_cset()) {
5799 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5800 _failures = true;
5801 return true;
5802 }
5803 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5804 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5805 _failures = true;
5806 return true;
5807 }
5808 } else {
5809 if (cset_state.is_humongous()) {
5810 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5811 _failures = true;
5812 return true;
5813 }
5814 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5815 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5816 hr->in_collection_set(), cset_state.value(), i);
5817 _failures = true;
5818 return true;
5819 }
5820 if (cset_state.is_in_cset()) {
5821 if (hr->is_young() != (cset_state.is_young())) {
5822 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5823 hr->is_young(), cset_state.value(), i);
5824 _failures = true;
5825 return true;
5826 }
5827 if (hr->is_old() != (cset_state.is_old())) {
5828 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5829 hr->is_old(), cset_state.value(), i);
5830 _failures = true;
5831 return true;
5832 }
5833 }
5834 }
5835 return false;
5836 }
5837
5838 bool failures() const { return _failures; }
5839 };
5840
5841 bool G1CollectedHeap::check_cset_fast_test() {
5842 G1CheckCSetFastTableClosure cl;
5843 _hrm.iterate(&cl);
5844 return !cl.failures();
5845 }
5846 #endif // PRODUCT
5847
5848 void G1CollectedHeap::cleanUpCardTable() {
5849 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5850 double start = os::elapsedTime();
5851
5852 {
5853 // Iterate over the dirty cards region list.
5854 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5855
5856 set_par_threads();
5857 workers()->run_task(&cleanup_task);
5858 set_par_threads(0);
5859 #ifndef PRODUCT
5860 if (G1VerifyCTCleanup || VerifyAfterGC) {
5861 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5862 heap_region_iterate(&cleanup_verifier);
5863 }
5864 #endif
5865 }
5866
5867 double elapsed = os::elapsedTime() - start;
5868 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5869 }
5870
5871 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5872 size_t pre_used = 0;
5873 FreeRegionList local_free_list("Local List for CSet Freeing");
5874
5875 double young_time_ms = 0.0;
5876 double non_young_time_ms = 0.0;
5877
5878 // Since the collection set is a superset of the the young list,
5879 // all we need to do to clear the young list is clear its
5880 // head and length, and unlink any young regions in the code below
5881 _young_list->clear();
5882
5883 G1CollectorPolicy* policy = g1_policy();
5884
5885 double start_sec = os::elapsedTime();
5886 bool non_young = true;
5887
5888 HeapRegion* cur = cs_head;
5889 int age_bound = -1;
5890 size_t rs_lengths = 0;
5891
5892 while (cur != NULL) {
5893 assert(!is_on_master_free_list(cur), "sanity");
5894 if (non_young) {
5895 if (cur->is_young()) {
5896 double end_sec = os::elapsedTime();
5897 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5898 non_young_time_ms += elapsed_ms;
5899
5900 start_sec = os::elapsedTime();
5901 non_young = false;
5902 }
5903 } else {
5904 if (!cur->is_young()) {
5905 double end_sec = os::elapsedTime();
5906 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5907 young_time_ms += elapsed_ms;
5908
5909 start_sec = os::elapsedTime();
5910 non_young = true;
5911 }
5912 }
5913
5914 rs_lengths += cur->rem_set()->occupied_locked();
5915
5916 HeapRegion* next = cur->next_in_collection_set();
5917 assert(cur->in_collection_set(), "bad CS");
5918 cur->set_next_in_collection_set(NULL);
5919 clear_in_cset(cur);
5920
5921 if (cur->is_young()) {
5922 int index = cur->young_index_in_cset();
5923 assert(index != -1, "invariant");
5924 assert((uint) index < policy->young_cset_region_length(), "invariant");
5925 size_t words_survived = _surviving_young_words[index];
5926 cur->record_surv_words_in_group(words_survived);
5927
5928 // At this point the we have 'popped' cur from the collection set
5929 // (linked via next_in_collection_set()) but it is still in the
5930 // young list (linked via next_young_region()). Clear the
5931 // _next_young_region field.
5932 cur->set_next_young_region(NULL);
5933 } else {
5934 int index = cur->young_index_in_cset();
5935 assert(index == -1, "invariant");
5936 }
5937
5938 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5939 (!cur->is_young() && cur->young_index_in_cset() == -1),
5940 "invariant" );
5941
5942 if (!cur->evacuation_failed()) {
5943 MemRegion used_mr = cur->used_region();
5944
5945 // And the region is empty.
5946 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5947 pre_used += cur->used();
5948 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5949 } else {
5950 cur->uninstall_surv_rate_group();
5951 if (cur->is_young()) {
5952 cur->set_young_index_in_cset(-1);
5953 }
5954 cur->set_evacuation_failed(false);
5955 // The region is now considered to be old.
5956 cur->set_old();
5957 _old_set.add(cur);
5958 evacuation_info.increment_collectionset_used_after(cur->used());
5959 }
5960 cur = next;
5961 }
5962
5963 evacuation_info.set_regions_freed(local_free_list.length());
5964 policy->record_max_rs_lengths(rs_lengths);
5965 policy->cset_regions_freed();
5966
5967 double end_sec = os::elapsedTime();
5968 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5969
5970 if (non_young) {
5971 non_young_time_ms += elapsed_ms;
5972 } else {
5973 young_time_ms += elapsed_ms;
5974 }
5975
5976 prepend_to_freelist(&local_free_list);
5977 decrement_summary_bytes(pre_used);
5978 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5979 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5980 }
5981
5982 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5983 private:
5984 FreeRegionList* _free_region_list;
5985 HeapRegionSet* _proxy_set;
5986 HeapRegionSetCount _humongous_regions_removed;
5987 size_t _freed_bytes;
5988 public:
5989
5990 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5991 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5992 }
5993
5994 virtual bool doHeapRegion(HeapRegion* r) {
5995 if (!r->is_starts_humongous()) {
5996 return false;
5997 }
5998
5999 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6000
6001 oop obj = (oop)r->bottom();
6002 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6003
6004 // The following checks whether the humongous object is live are sufficient.
6005 // The main additional check (in addition to having a reference from the roots
6006 // or the young gen) is whether the humongous object has a remembered set entry.
6007 //
6008 // A humongous object cannot be live if there is no remembered set for it
6009 // because:
6010 // - there can be no references from within humongous starts regions referencing
6011 // the object because we never allocate other objects into them.
6012 // (I.e. there are no intra-region references that may be missed by the
6013 // remembered set)
6014 // - as soon there is a remembered set entry to the humongous starts region
6015 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6016 // until the end of a concurrent mark.
6017 //
6018 // It is not required to check whether the object has been found dead by marking
6019 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6020 // all objects allocated during that time are considered live.
6021 // SATB marking is even more conservative than the remembered set.
6022 // So if at this point in the collection there is no remembered set entry,
6023 // nobody has a reference to it.
6024 // At the start of collection we flush all refinement logs, and remembered sets
6025 // are completely up-to-date wrt to references to the humongous object.
6026 //
6027 // Other implementation considerations:
6028 // - never consider object arrays at this time because they would pose
6029 // considerable effort for cleaning up the the remembered sets. This is
6030 // required because stale remembered sets might reference locations that
6031 // are currently allocated into.
6032 uint region_idx = r->hrm_index();
6033 if (g1h->humongous_is_live(region_idx) ||
6034 g1h->humongous_region_is_always_live(region_idx)) {
6035
6036 if (G1TraceEagerReclaimHumongousObjects) {
6037 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6038 region_idx,
6039 obj->size()*HeapWordSize,
6040 r->bottom(),
6041 r->region_num(),
6042 r->rem_set()->occupied(),
6043 r->rem_set()->strong_code_roots_list_length(),
6044 next_bitmap->isMarked(r->bottom()),
6045 g1h->humongous_is_live(region_idx),
6046 obj->is_objArray()
6047 );
6048 }
6049
6050 return false;
6051 }
6052
6053 guarantee(!obj->is_objArray(),
6054 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6055 r->bottom()));
6056
6057 if (G1TraceEagerReclaimHumongousObjects) {
6058 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6059 region_idx,
6060 obj->size()*HeapWordSize,
6061 r->bottom(),
6062 r->region_num(),
6063 r->rem_set()->occupied(),
6064 r->rem_set()->strong_code_roots_list_length(),
6065 next_bitmap->isMarked(r->bottom()),
6066 g1h->humongous_is_live(region_idx),
6067 obj->is_objArray()
6068 );
6069 }
6070 // Need to clear mark bit of the humongous object if already set.
6071 if (next_bitmap->isMarked(r->bottom())) {
6072 next_bitmap->clear(r->bottom());
6073 }
6074 _freed_bytes += r->used();
6075 r->set_containing_set(NULL);
6076 _humongous_regions_removed.increment(1u, r->capacity());
6077 g1h->free_humongous_region(r, _free_region_list, false);
6078
6079 return false;
6080 }
6081
6082 HeapRegionSetCount& humongous_free_count() {
6083 return _humongous_regions_removed;
6084 }
6085
6086 size_t bytes_freed() const {
6087 return _freed_bytes;
6088 }
6089
6090 size_t humongous_reclaimed() const {
6091 return _humongous_regions_removed.length();
6092 }
6093 };
6094
6095 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6096 assert_at_safepoint(true);
6097
6098 if (!G1EagerReclaimHumongousObjects ||
6099 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6100 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6101 return;
6102 }
6103
6104 double start_time = os::elapsedTime();
6105
6106 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6107
6108 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6109 heap_region_iterate(&cl);
6110
6111 HeapRegionSetCount empty_set;
6112 remove_from_old_sets(empty_set, cl.humongous_free_count());
6113
6114 G1HRPrinter* hr_printer = _g1h->hr_printer();
6115 if (hr_printer->is_active()) {
6116 FreeRegionListIterator iter(&local_cleanup_list);
6117 while (iter.more_available()) {
6118 HeapRegion* hr = iter.get_next();
6119 hr_printer->cleanup(hr);
6120 }
6121 }
6122
6123 prepend_to_freelist(&local_cleanup_list);
6124 decrement_summary_bytes(cl.bytes_freed());
6125
6126 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6127 cl.humongous_reclaimed());
6128 }
6129
6130 // This routine is similar to the above but does not record
6131 // any policy statistics or update free lists; we are abandoning
6132 // the current incremental collection set in preparation of a
6133 // full collection. After the full GC we will start to build up
6134 // the incremental collection set again.
6135 // This is only called when we're doing a full collection
6136 // and is immediately followed by the tearing down of the young list.
6137
6138 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6139 HeapRegion* cur = cs_head;
6140
6141 while (cur != NULL) {
6142 HeapRegion* next = cur->next_in_collection_set();
6143 assert(cur->in_collection_set(), "bad CS");
6144 cur->set_next_in_collection_set(NULL);
6145 clear_in_cset(cur);
6146 cur->set_young_index_in_cset(-1);
6147 cur = next;
6148 }
6149 }
6150
6151 void G1CollectedHeap::set_free_regions_coming() {
6152 if (G1ConcRegionFreeingVerbose) {
6153 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6154 "setting free regions coming");
6155 }
6156
6157 assert(!free_regions_coming(), "pre-condition");
6158 _free_regions_coming = true;
6159 }
6160
6161 void G1CollectedHeap::reset_free_regions_coming() {
6162 assert(free_regions_coming(), "pre-condition");
6163
6164 {
6165 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6166 _free_regions_coming = false;
6167 SecondaryFreeList_lock->notify_all();
6168 }
6169
6170 if (G1ConcRegionFreeingVerbose) {
6171 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6172 "reset free regions coming");
6173 }
6174 }
6175
6176 void G1CollectedHeap::wait_while_free_regions_coming() {
6177 // Most of the time we won't have to wait, so let's do a quick test
6178 // first before we take the lock.
6179 if (!free_regions_coming()) {
6180 return;
6181 }
6182
6183 if (G1ConcRegionFreeingVerbose) {
6184 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6185 "waiting for free regions");
6186 }
6187
6188 {
6189 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6190 while (free_regions_coming()) {
6191 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6192 }
6193 }
6194
6195 if (G1ConcRegionFreeingVerbose) {
6196 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6197 "done waiting for free regions");
6198 }
6199 }
6200
6201 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6202 assert(heap_lock_held_for_gc(),
6203 "the heap lock should already be held by or for this thread");
6204 _young_list->push_region(hr);
6205 }
6206
6207 class NoYoungRegionsClosure: public HeapRegionClosure {
6208 private:
6209 bool _success;
6210 public:
6211 NoYoungRegionsClosure() : _success(true) { }
6212 bool doHeapRegion(HeapRegion* r) {
6213 if (r->is_young()) {
6214 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6215 r->bottom(), r->end());
6216 _success = false;
6217 }
6218 return false;
6219 }
6220 bool success() { return _success; }
6221 };
6222
6223 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6224 bool ret = _young_list->check_list_empty(check_sample);
6225
6226 if (check_heap) {
6227 NoYoungRegionsClosure closure;
6228 heap_region_iterate(&closure);
6229 ret = ret && closure.success();
6230 }
6231
6232 return ret;
6233 }
6234
6235 class TearDownRegionSetsClosure : public HeapRegionClosure {
6236 private:
6237 HeapRegionSet *_old_set;
6238
6239 public:
6240 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6241
6242 bool doHeapRegion(HeapRegion* r) {
6243 if (r->is_old()) {
6244 _old_set->remove(r);
6245 } else {
6246 // We ignore free regions, we'll empty the free list afterwards.
6247 // We ignore young regions, we'll empty the young list afterwards.
6248 // We ignore humongous regions, we're not tearing down the
6249 // humongous regions set.
6250 assert(r->is_free() || r->is_young() || r->is_humongous(),
6251 "it cannot be another type");
6252 }
6253 return false;
6254 }
6255
6256 ~TearDownRegionSetsClosure() {
6257 assert(_old_set->is_empty(), "post-condition");
6258 }
6259 };
6260
6261 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6262 assert_at_safepoint(true /* should_be_vm_thread */);
6263
6264 if (!free_list_only) {
6265 TearDownRegionSetsClosure cl(&_old_set);
6266 heap_region_iterate(&cl);
6267
6268 // Note that emptying the _young_list is postponed and instead done as
6269 // the first step when rebuilding the regions sets again. The reason for
6270 // this is that during a full GC string deduplication needs to know if
6271 // a collected region was young or old when the full GC was initiated.
6272 }
6273 _hrm.remove_all_free_regions();
6274 }
6275
6276 class RebuildRegionSetsClosure : public HeapRegionClosure {
6277 private:
6278 bool _free_list_only;
6279 HeapRegionSet* _old_set;
6280 HeapRegionManager* _hrm;
6281 size_t _total_used;
6282
6283 public:
6284 RebuildRegionSetsClosure(bool free_list_only,
6285 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6286 _free_list_only(free_list_only),
6287 _old_set(old_set), _hrm(hrm), _total_used(0) {
6288 assert(_hrm->num_free_regions() == 0, "pre-condition");
6289 if (!free_list_only) {
6290 assert(_old_set->is_empty(), "pre-condition");
6291 }
6292 }
6293
6294 bool doHeapRegion(HeapRegion* r) {
6295 if (r->is_continues_humongous()) {
6296 return false;
6297 }
6298
6299 if (r->is_empty()) {
6300 // Add free regions to the free list
6301 r->set_free();
6302 r->set_allocation_context(AllocationContext::system());
6303 _hrm->insert_into_free_list(r);
6304 } else if (!_free_list_only) {
6305 assert(!r->is_young(), "we should not come across young regions");
6306
6307 if (r->is_humongous()) {
6308 // We ignore humongous regions, we left the humongous set unchanged
6309 } else {
6310 // Objects that were compacted would have ended up on regions
6311 // that were previously old or free.
6312 assert(r->is_free() || r->is_old(), "invariant");
6313 // We now consider them old, so register as such.
6314 r->set_old();
6315 _old_set->add(r);
6316 }
6317 _total_used += r->used();
6318 }
6319
6320 return false;
6321 }
6322
6323 size_t total_used() {
6324 return _total_used;
6325 }
6326 };
6327
6328 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6329 assert_at_safepoint(true /* should_be_vm_thread */);
6330
6331 if (!free_list_only) {
6332 _young_list->empty_list();
6333 }
6334
6335 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6336 heap_region_iterate(&cl);
6337
6338 if (!free_list_only) {
6339 _allocator->set_used(cl.total_used());
6340 }
6341 assert(_allocator->used_unlocked() == recalculate_used(),
6342 err_msg("inconsistent _allocator->used_unlocked(), "
6343 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6344 _allocator->used_unlocked(), recalculate_used()));
6345 }
6346
6347 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6348 _refine_cte_cl->set_concurrent(concurrent);
6349 }
6350
6351 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6352 HeapRegion* hr = heap_region_containing(p);
6353 return hr->is_in(p);
6354 }
6355
6356 // Methods for the mutator alloc region
6357
6358 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6359 bool force) {
6360 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6361 assert(!force || g1_policy()->can_expand_young_list(),
6362 "if force is true we should be able to expand the young list");
6363 bool young_list_full = g1_policy()->is_young_list_full();
6364 if (force || !young_list_full) {
6365 HeapRegion* new_alloc_region = new_region(word_size,
6366 false /* is_old */,
6367 false /* do_expand */);
6368 if (new_alloc_region != NULL) {
6369 set_region_short_lived_locked(new_alloc_region);
6370 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6371 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6372 return new_alloc_region;
6373 }
6374 }
6375 return NULL;
6376 }
6377
6378 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6379 size_t allocated_bytes) {
6380 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6381 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6382
6383 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6384 _allocator->increase_used(allocated_bytes);
6385 _hr_printer.retire(alloc_region);
6386 // We update the eden sizes here, when the region is retired,
6387 // instead of when it's allocated, since this is the point that its
6388 // used space has been recored in _summary_bytes_used.
6389 g1mm()->update_eden_size();
6390 }
6391
6392 void G1CollectedHeap::set_par_threads() {
6393 // Don't change the number of workers. Use the value previously set
6394 // in the workgroup.
6395 uint n_workers = workers()->active_workers();
6396 assert(UseDynamicNumberOfGCThreads ||
6397 n_workers == workers()->total_workers(),
6398 "Otherwise should be using the total number of workers");
6399 if (n_workers == 0) {
6400 assert(false, "Should have been set in prior evacuation pause.");
6401 n_workers = ParallelGCThreads;
6402 workers()->set_active_workers(n_workers);
6403 }
6404 set_par_threads(n_workers);
6405 }
6406
6407 // Methods for the GC alloc regions
6408
6409 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6410 uint count,
6411 InCSetState dest) {
6412 assert(FreeList_lock->owned_by_self(), "pre-condition");
6413
6414 if (count < g1_policy()->max_regions(dest)) {
6415 const bool is_survivor = (dest.is_young());
6416 HeapRegion* new_alloc_region = new_region(word_size,
6417 !is_survivor,
6418 true /* do_expand */);
6419 if (new_alloc_region != NULL) {
6420 // We really only need to do this for old regions given that we
6421 // should never scan survivors. But it doesn't hurt to do it
6422 // for survivors too.
6423 new_alloc_region->record_timestamp();
6424 if (is_survivor) {
6425 new_alloc_region->set_survivor();
6426 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6427 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6428 } else {
6429 new_alloc_region->set_old();
6430 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6431 check_bitmaps("Old Region Allocation", new_alloc_region);
6432 }
6433 bool during_im = g1_policy()->during_initial_mark_pause();
6434 new_alloc_region->note_start_of_copying(during_im);
6435 return new_alloc_region;
6436 }
6437 }
6438 return NULL;
6439 }
6440
6441 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6442 size_t allocated_bytes,
6443 InCSetState dest) {
6444 bool during_im = g1_policy()->during_initial_mark_pause();
6445 alloc_region->note_end_of_copying(during_im);
6446 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6447 if (dest.is_young()) {
6448 young_list()->add_survivor_region(alloc_region);
6449 } else {
6450 _old_set.add(alloc_region);
6451 }
6452 _hr_printer.retire(alloc_region);
6453 }
6454
6455 // Heap region set verification
6456
6457 class VerifyRegionListsClosure : public HeapRegionClosure {
6458 private:
6459 HeapRegionSet* _old_set;
6460 HeapRegionSet* _humongous_set;
6461 HeapRegionManager* _hrm;
6462
6463 public:
6464 HeapRegionSetCount _old_count;
6465 HeapRegionSetCount _humongous_count;
6466 HeapRegionSetCount _free_count;
6467
6468 VerifyRegionListsClosure(HeapRegionSet* old_set,
6469 HeapRegionSet* humongous_set,
6470 HeapRegionManager* hrm) :
6471 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6472 _old_count(), _humongous_count(), _free_count(){ }
6473
6474 bool doHeapRegion(HeapRegion* hr) {
6475 if (hr->is_continues_humongous()) {
6476 return false;
6477 }
6478
6479 if (hr->is_young()) {
6480 // TODO
6481 } else if (hr->is_starts_humongous()) {
6482 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6483 _humongous_count.increment(1u, hr->capacity());
6484 } else if (hr->is_empty()) {
6485 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6486 _free_count.increment(1u, hr->capacity());
6487 } else if (hr->is_old()) {
6488 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6489 _old_count.increment(1u, hr->capacity());
6490 } else {
6491 ShouldNotReachHere();
6492 }
6493 return false;
6494 }
6495
6496 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6497 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6498 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6499 old_set->total_capacity_bytes(), _old_count.capacity()));
6500
6501 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6502 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6503 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6504
6505 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()));
6506 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6507 free_list->total_capacity_bytes(), _free_count.capacity()));
6508 }
6509 };
6510
6511 void G1CollectedHeap::verify_region_sets() {
6512 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6513
6514 // First, check the explicit lists.
6515 _hrm.verify();
6516 {
6517 // Given that a concurrent operation might be adding regions to
6518 // the secondary free list we have to take the lock before
6519 // verifying it.
6520 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6521 _secondary_free_list.verify_list();
6522 }
6523
6524 // If a concurrent region freeing operation is in progress it will
6525 // be difficult to correctly attributed any free regions we come
6526 // across to the correct free list given that they might belong to
6527 // one of several (free_list, secondary_free_list, any local lists,
6528 // etc.). So, if that's the case we will skip the rest of the
6529 // verification operation. Alternatively, waiting for the concurrent
6530 // operation to complete will have a non-trivial effect on the GC's
6531 // operation (no concurrent operation will last longer than the
6532 // interval between two calls to verification) and it might hide
6533 // any issues that we would like to catch during testing.
6534 if (free_regions_coming()) {
6535 return;
6536 }
6537
6538 // Make sure we append the secondary_free_list on the free_list so
6539 // that all free regions we will come across can be safely
6540 // attributed to the free_list.
6541 append_secondary_free_list_if_not_empty_with_lock();
6542
6543 // Finally, make sure that the region accounting in the lists is
6544 // consistent with what we see in the heap.
6545
6546 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6547 heap_region_iterate(&cl);
6548 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6549 }
6550
6551 // Optimized nmethod scanning
6552
6553 class RegisterNMethodOopClosure: public OopClosure {
6554 G1CollectedHeap* _g1h;
6555 nmethod* _nm;
6556
6557 template <class T> void do_oop_work(T* p) {
6558 T heap_oop = oopDesc::load_heap_oop(p);
6559 if (!oopDesc::is_null(heap_oop)) {
6560 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6561 HeapRegion* hr = _g1h->heap_region_containing(obj);
6562 assert(!hr->is_continues_humongous(),
6563 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6564 " starting at "HR_FORMAT,
6565 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6566
6567 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6568 hr->add_strong_code_root_locked(_nm);
6569 }
6570 }
6571
6572 public:
6573 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6574 _g1h(g1h), _nm(nm) {}
6575
6576 void do_oop(oop* p) { do_oop_work(p); }
6577 void do_oop(narrowOop* p) { do_oop_work(p); }
6578 };
6579
6580 class UnregisterNMethodOopClosure: public OopClosure {
6581 G1CollectedHeap* _g1h;
6582 nmethod* _nm;
6583
6584 template <class T> void do_oop_work(T* p) {
6585 T heap_oop = oopDesc::load_heap_oop(p);
6586 if (!oopDesc::is_null(heap_oop)) {
6587 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6588 HeapRegion* hr = _g1h->heap_region_containing(obj);
6589 assert(!hr->is_continues_humongous(),
6590 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6591 " starting at "HR_FORMAT,
6592 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6593
6594 hr->remove_strong_code_root(_nm);
6595 }
6596 }
6597
6598 public:
6599 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6600 _g1h(g1h), _nm(nm) {}
6601
6602 void do_oop(oop* p) { do_oop_work(p); }
6603 void do_oop(narrowOop* p) { do_oop_work(p); }
6604 };
6605
6606 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6607 CollectedHeap::register_nmethod(nm);
6608
6609 guarantee(nm != NULL, "sanity");
6610 RegisterNMethodOopClosure reg_cl(this, nm);
6611 nm->oops_do(®_cl);
6612 }
6613
6614 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6615 CollectedHeap::unregister_nmethod(nm);
6616
6617 guarantee(nm != NULL, "sanity");
6618 UnregisterNMethodOopClosure reg_cl(this, nm);
6619 nm->oops_do(®_cl, true);
6620 }
6621
6622 void G1CollectedHeap::purge_code_root_memory() {
6623 double purge_start = os::elapsedTime();
6624 G1CodeRootSet::purge();
6625 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6626 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6627 }
6628
6629 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6630 G1CollectedHeap* _g1h;
6631
6632 public:
6633 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6634 _g1h(g1h) {}
6635
6636 void do_code_blob(CodeBlob* cb) {
6637 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6638 if (nm == NULL) {
6639 return;
6640 }
6641
6642 if (ScavengeRootsInCode) {
6643 _g1h->register_nmethod(nm);
6644 }
6645 }
6646 };
6647
6648 void G1CollectedHeap::rebuild_strong_code_roots() {
6649 RebuildStrongCodeRootClosure blob_cl(this);
6650 CodeCache::blobs_do(&blob_cl);
6651 }