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