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 // Notes on implementation of parallelism in different tasks.
94 //
95 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
96 // The number of GC workers is passed to heap_region_par_iterate().
97 // It does use run_task() which sets _n_workers in the task.
98 // G1ParTask executes g1_process_roots() ->
99 // SharedHeap::process_roots() which calls eventually to
100 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
101 // SequentialSubTasksDone. SharedHeap::process_roots() also
102 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
103 //
104
105 // Local to this file.
106
107 class RefineCardTableEntryClosure: public CardTableEntryClosure {
108 bool _concurrent;
109 public:
110 RefineCardTableEntryClosure() : _concurrent(true) { }
111
112 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
113 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
114 // This path is executed by the concurrent refine or mutator threads,
115 // concurrently, and so we do not care if card_ptr contains references
116 // that point into the collection set.
117 assert(!oops_into_cset, "should be");
118
119 if (_concurrent && SuspendibleThreadSet::should_yield()) {
120 // Caller will actually yield.
121 return false;
122 }
123 // Otherwise, we finished successfully; return true.
124 return true;
125 }
126
127 void set_concurrent(bool b) { _concurrent = b; }
128 };
129
130
131 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
132 private:
133 size_t _num_processed;
134
135 public:
136 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
137
138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
139 *card_ptr = CardTableModRefBS::dirty_card_val();
140 _num_processed++;
141 return true;
142 }
143
144 size_t num_processed() const { return _num_processed; }
145 };
146
147 YoungList::YoungList(G1CollectedHeap* g1h) :
148 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
149 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
150 guarantee(check_list_empty(false), "just making sure...");
151 }
152
153 void YoungList::push_region(HeapRegion *hr) {
154 assert(!hr->is_young(), "should not already be young");
155 assert(hr->get_next_young_region() == NULL, "cause it should!");
156
157 hr->set_next_young_region(_head);
158 _head = hr;
159
160 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
161 ++_length;
162 }
163
164 void YoungList::add_survivor_region(HeapRegion* hr) {
165 assert(hr->is_survivor(), "should be flagged as survivor region");
166 assert(hr->get_next_young_region() == NULL, "cause it should!");
167
168 hr->set_next_young_region(_survivor_head);
169 if (_survivor_head == NULL) {
170 _survivor_tail = hr;
171 }
172 _survivor_head = hr;
173 ++_survivor_length;
174 }
175
176 void YoungList::empty_list(HeapRegion* list) {
177 while (list != NULL) {
178 HeapRegion* next = list->get_next_young_region();
179 list->set_next_young_region(NULL);
180 list->uninstall_surv_rate_group();
181 // This is called before a Full GC and all the non-empty /
182 // non-humongous regions at the end of the Full GC will end up as
183 // old anyway.
184 list->set_old();
185 list = next;
186 }
187 }
188
189 void YoungList::empty_list() {
190 assert(check_list_well_formed(), "young list should be well formed");
191
192 empty_list(_head);
193 _head = NULL;
194 _length = 0;
195
196 empty_list(_survivor_head);
197 _survivor_head = NULL;
198 _survivor_tail = NULL;
199 _survivor_length = 0;
200
201 _last_sampled_rs_lengths = 0;
202
203 assert(check_list_empty(false), "just making sure...");
204 }
205
206 bool YoungList::check_list_well_formed() {
207 bool ret = true;
208
209 uint length = 0;
210 HeapRegion* curr = _head;
211 HeapRegion* last = NULL;
212 while (curr != NULL) {
213 if (!curr->is_young()) {
214 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
215 "incorrectly tagged (y: %d, surv: %d)",
216 curr->bottom(), curr->end(),
217 curr->is_young(), curr->is_survivor());
218 ret = false;
219 }
220 ++length;
221 last = curr;
222 curr = curr->get_next_young_region();
223 }
224 ret = ret && (length == _length);
225
226 if (!ret) {
227 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
228 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
229 length, _length);
230 }
231
232 return ret;
233 }
234
235 bool YoungList::check_list_empty(bool check_sample) {
236 bool ret = true;
237
238 if (_length != 0) {
239 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
240 _length);
241 ret = false;
242 }
243 if (check_sample && _last_sampled_rs_lengths != 0) {
244 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
245 ret = false;
246 }
247 if (_head != NULL) {
248 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
249 ret = false;
250 }
251 if (!ret) {
252 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
253 }
254
255 return ret;
256 }
257
258 void
259 YoungList::rs_length_sampling_init() {
260 _sampled_rs_lengths = 0;
261 _curr = _head;
262 }
263
264 bool
265 YoungList::rs_length_sampling_more() {
266 return _curr != NULL;
267 }
268
269 void
270 YoungList::rs_length_sampling_next() {
271 assert( _curr != NULL, "invariant" );
272 size_t rs_length = _curr->rem_set()->occupied();
273
274 _sampled_rs_lengths += rs_length;
275
276 // The current region may not yet have been added to the
277 // incremental collection set (it gets added when it is
278 // retired as the current allocation region).
279 if (_curr->in_collection_set()) {
280 // Update the collection set policy information for this region
281 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
282 }
283
284 _curr = _curr->get_next_young_region();
285 if (_curr == NULL) {
286 _last_sampled_rs_lengths = _sampled_rs_lengths;
287 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
288 }
289 }
290
291 void
292 YoungList::reset_auxilary_lists() {
293 guarantee( is_empty(), "young list should be empty" );
294 assert(check_list_well_formed(), "young list should be well formed");
295
296 // Add survivor regions to SurvRateGroup.
297 _g1h->g1_policy()->note_start_adding_survivor_regions();
298 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
299
300 int young_index_in_cset = 0;
301 for (HeapRegion* curr = _survivor_head;
302 curr != NULL;
303 curr = curr->get_next_young_region()) {
304 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
305
306 // The region is a non-empty survivor so let's add it to
307 // the incremental collection set for the next evacuation
308 // pause.
309 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
310 young_index_in_cset += 1;
311 }
312 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
313 _g1h->g1_policy()->note_stop_adding_survivor_regions();
314
315 _head = _survivor_head;
316 _length = _survivor_length;
317 if (_survivor_head != NULL) {
318 assert(_survivor_tail != NULL, "cause it shouldn't be");
319 assert(_survivor_length > 0, "invariant");
320 _survivor_tail->set_next_young_region(NULL);
321 }
322
323 // Don't clear the survivor list handles until the start of
324 // the next evacuation pause - we need it in order to re-tag
325 // the survivor regions from this evacuation pause as 'young'
326 // at the start of the next.
327
328 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
329
330 assert(check_list_well_formed(), "young list should be well formed");
331 }
332
333 void YoungList::print() {
334 HeapRegion* lists[] = {_head, _survivor_head};
335 const char* names[] = {"YOUNG", "SURVIVOR"};
336
337 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
338 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
339 HeapRegion *curr = lists[list];
340 if (curr == NULL)
341 gclog_or_tty->print_cr(" empty");
342 while (curr != NULL) {
343 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
344 HR_FORMAT_PARAMS(curr),
345 curr->prev_top_at_mark_start(),
346 curr->next_top_at_mark_start(),
347 curr->age_in_surv_rate_group_cond());
348 curr = curr->get_next_young_region();
349 }
350 }
351
352 gclog_or_tty->cr();
353 }
354
355 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
356 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
357 }
358
359 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
360 // The from card cache is not the memory that is actually committed. So we cannot
361 // take advantage of the zero_filled parameter.
362 reset_from_card_cache(start_idx, num_regions);
363 }
364
365 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
366 {
367 // Claim the right to put the region on the dirty cards region list
368 // by installing a self pointer.
369 HeapRegion* next = hr->get_next_dirty_cards_region();
370 if (next == NULL) {
371 HeapRegion* res = (HeapRegion*)
372 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
373 NULL);
374 if (res == NULL) {
375 HeapRegion* head;
376 do {
377 // Put the region to the dirty cards region list.
378 head = _dirty_cards_region_list;
379 next = (HeapRegion*)
380 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
381 if (next == head) {
382 assert(hr->get_next_dirty_cards_region() == hr,
383 "hr->get_next_dirty_cards_region() != hr");
384 if (next == NULL) {
385 // The last region in the list points to itself.
386 hr->set_next_dirty_cards_region(hr);
387 } else {
388 hr->set_next_dirty_cards_region(next);
389 }
390 }
391 } while (next != head);
392 }
393 }
394 }
395
396 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
397 {
398 HeapRegion* head;
399 HeapRegion* hr;
400 do {
401 head = _dirty_cards_region_list;
402 if (head == NULL) {
403 return NULL;
404 }
405 HeapRegion* new_head = head->get_next_dirty_cards_region();
406 if (head == new_head) {
407 // The last region.
408 new_head = NULL;
409 }
410 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
411 head);
412 } while (hr != head);
413 assert(hr != NULL, "invariant");
414 hr->set_next_dirty_cards_region(NULL);
415 return hr;
416 }
417
418 #ifdef ASSERT
419 // A region is added to the collection set as it is retired
420 // so an address p can point to a region which will be in the
421 // collection set but has not yet been retired. This method
422 // therefore is only accurate during a GC pause after all
423 // regions have been retired. It is used for debugging
424 // to check if an nmethod has references to objects that can
425 // be move during a partial collection. Though it can be
426 // inaccurate, it is sufficient for G1 because the conservative
427 // implementation of is_scavengable() for G1 will indicate that
428 // all nmethods must be scanned during a partial collection.
429 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
430 if (p == NULL) {
431 return false;
432 }
433 return heap_region_containing(p)->in_collection_set();
434 }
435 #endif
436
437 // Returns true if the reference points to an object that
438 // can move in an incremental collection.
439 bool G1CollectedHeap::is_scavengable(const void* p) {
440 HeapRegion* hr = heap_region_containing(p);
441 return !hr->is_humongous();
442 }
443
444 // Private class members.
445
446 G1CollectedHeap* G1CollectedHeap::_g1h;
447
448 // Private methods.
449
450 HeapRegion*
451 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
452 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
453 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
454 if (!_secondary_free_list.is_empty()) {
455 if (G1ConcRegionFreeingVerbose) {
456 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
457 "secondary_free_list has %u entries",
458 _secondary_free_list.length());
459 }
460 // It looks as if there are free regions available on the
461 // secondary_free_list. Let's move them to the free_list and try
462 // again to allocate from it.
463 append_secondary_free_list();
464
465 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
466 "empty we should have moved at least one entry to the free_list");
467 HeapRegion* res = _hrm.allocate_free_region(is_old);
468 if (G1ConcRegionFreeingVerbose) {
469 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
470 "allocated "HR_FORMAT" from secondary_free_list",
471 HR_FORMAT_PARAMS(res));
472 }
473 return res;
474 }
475
476 // Wait here until we get notified either when (a) there are no
477 // more free regions coming or (b) some regions have been moved on
478 // the secondary_free_list.
479 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
480 }
481
482 if (G1ConcRegionFreeingVerbose) {
483 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
484 "could not allocate from secondary_free_list");
485 }
486 return NULL;
487 }
488
489 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
490 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
491 "the only time we use this to allocate a humongous region is "
492 "when we are allocating a single humongous region");
493
494 HeapRegion* res;
495 if (G1StressConcRegionFreeing) {
496 if (!_secondary_free_list.is_empty()) {
497 if (G1ConcRegionFreeingVerbose) {
498 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
499 "forced to look at the secondary_free_list");
500 }
501 res = new_region_try_secondary_free_list(is_old);
502 if (res != NULL) {
503 return res;
504 }
505 }
506 }
507
508 res = _hrm.allocate_free_region(is_old);
509
510 if (res == NULL) {
511 if (G1ConcRegionFreeingVerbose) {
512 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
513 "res == NULL, trying the secondary_free_list");
514 }
515 res = new_region_try_secondary_free_list(is_old);
516 }
517 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
518 // Currently, only attempts to allocate GC alloc regions set
519 // do_expand to true. So, we should only reach here during a
520 // safepoint. If this assumption changes we might have to
521 // reconsider the use of _expand_heap_after_alloc_failure.
522 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
523
524 ergo_verbose1(ErgoHeapSizing,
525 "attempt heap expansion",
526 ergo_format_reason("region allocation request failed")
527 ergo_format_byte("allocation request"),
528 word_size * HeapWordSize);
529 if (expand(word_size * HeapWordSize)) {
530 // Given that expand() succeeded in expanding the heap, and we
531 // always expand the heap by an amount aligned to the heap
532 // region size, the free list should in theory not be empty.
533 // In either case allocate_free_region() will check for NULL.
534 res = _hrm.allocate_free_region(is_old);
535 } else {
536 _expand_heap_after_alloc_failure = false;
537 }
538 }
539 return res;
540 }
541
542 HeapWord*
543 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
544 uint num_regions,
545 size_t word_size,
546 AllocationContext_t context) {
547 assert(first != G1_NO_HRM_INDEX, "pre-condition");
548 assert(is_humongous(word_size), "word_size should be humongous");
549 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
550
551 // Index of last region in the series + 1.
552 uint last = first + num_regions;
553
554 // We need to initialize the region(s) we just discovered. This is
555 // a bit tricky given that it can happen concurrently with
556 // refinement threads refining cards on these regions and
557 // potentially wanting to refine the BOT as they are scanning
558 // those cards (this can happen shortly after a cleanup; see CR
559 // 6991377). So we have to set up the region(s) carefully and in
560 // a specific order.
561
562 // The word size sum of all the regions we will allocate.
563 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
564 assert(word_size <= word_size_sum, "sanity");
565
566 // This will be the "starts humongous" region.
567 HeapRegion* first_hr = region_at(first);
568 // The header of the new object will be placed at the bottom of
569 // the first region.
570 HeapWord* new_obj = first_hr->bottom();
571 // This will be the new end of the first region in the series that
572 // should also match the end of the last region in the series.
573 HeapWord* new_end = new_obj + word_size_sum;
574 // This will be the new top of the first region that will reflect
575 // this allocation.
576 HeapWord* new_top = new_obj + word_size;
577
578 // First, we need to zero the header of the space that we will be
579 // allocating. When we update top further down, some refinement
580 // threads might try to scan the region. By zeroing the header we
581 // ensure that any thread that will try to scan the region will
582 // come across the zero klass word and bail out.
583 //
584 // NOTE: It would not have been correct to have used
585 // CollectedHeap::fill_with_object() and make the space look like
586 // an int array. The thread that is doing the allocation will
587 // later update the object header to a potentially different array
588 // type and, for a very short period of time, the klass and length
589 // fields will be inconsistent. This could cause a refinement
590 // thread to calculate the object size incorrectly.
591 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
592
593 // We will set up the first region as "starts humongous". This
594 // will also update the BOT covering all the regions to reflect
595 // that there is a single object that starts at the bottom of the
596 // first region.
597 first_hr->set_starts_humongous(new_top, new_end);
598 first_hr->set_allocation_context(context);
599 // Then, if there are any, we will set up the "continues
600 // humongous" regions.
601 HeapRegion* hr = NULL;
602 for (uint i = first + 1; i < last; ++i) {
603 hr = region_at(i);
604 hr->set_continues_humongous(first_hr);
605 hr->set_allocation_context(context);
606 }
607 // If we have "continues humongous" regions (hr != NULL), then the
608 // end of the last one should match new_end.
609 assert(hr == NULL || hr->end() == new_end, "sanity");
610
611 // Up to this point no concurrent thread would have been able to
612 // do any scanning on any region in this series. All the top
613 // fields still point to bottom, so the intersection between
614 // [bottom,top] and [card_start,card_end] will be empty. Before we
615 // update the top fields, we'll do a storestore to make sure that
616 // no thread sees the update to top before the zeroing of the
617 // object header and the BOT initialization.
618 OrderAccess::storestore();
619
620 // Now that the BOT and the object header have been initialized,
621 // we can update top of the "starts humongous" region.
622 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
623 "new_top should be in this region");
624 first_hr->set_top(new_top);
625 if (_hr_printer.is_active()) {
626 HeapWord* bottom = first_hr->bottom();
627 HeapWord* end = first_hr->orig_end();
628 if ((first + 1) == last) {
629 // the series has a single humongous region
630 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
631 } else {
632 // the series has more than one humongous regions
633 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
634 }
635 }
636
637 // Now, we will update the top fields of the "continues humongous"
638 // regions. The reason we need to do this is that, otherwise,
639 // these regions would look empty and this will confuse parts of
640 // G1. For example, the code that looks for a consecutive number
641 // of empty regions will consider them empty and try to
642 // re-allocate them. We can extend is_empty() to also include
643 // !is_continues_humongous(), but it is easier to just update the top
644 // fields here. The way we set top for all regions (i.e., top ==
645 // end for all regions but the last one, top == new_top for the
646 // last one) is actually used when we will free up the humongous
647 // region in free_humongous_region().
648 hr = NULL;
649 for (uint i = first + 1; i < last; ++i) {
650 hr = region_at(i);
651 if ((i + 1) == last) {
652 // last continues humongous region
653 assert(hr->bottom() < new_top && new_top <= hr->end(),
654 "new_top should fall on this region");
655 hr->set_top(new_top);
656 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
657 } else {
658 // not last one
659 assert(new_top > hr->end(), "new_top should be above this region");
660 hr->set_top(hr->end());
661 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
662 }
663 }
664 // If we have continues humongous regions (hr != NULL), then the
665 // end of the last one should match new_end and its top should
666 // match new_top.
667 assert(hr == NULL ||
668 (hr->end() == new_end && hr->top() == new_top), "sanity");
669 check_bitmaps("Humongous Region Allocation", first_hr);
670
671 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
672 _allocator->increase_used(first_hr->used());
673 _humongous_set.add(first_hr);
674
675 return new_obj;
676 }
677
678 // If could fit into free regions w/o expansion, try.
679 // Otherwise, if can expand, do so.
680 // Otherwise, if using ex regions might help, try with ex given back.
681 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
682 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
683
684 verify_region_sets_optional();
685
686 uint first = G1_NO_HRM_INDEX;
687 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
688
689 if (obj_regions == 1) {
690 // Only one region to allocate, try to use a fast path by directly allocating
691 // from the free lists. Do not try to expand here, we will potentially do that
692 // later.
693 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
694 if (hr != NULL) {
695 first = hr->hrm_index();
696 }
697 } else {
698 // We can't allocate humongous regions spanning more than one region while
699 // cleanupComplete() is running, since some of the regions we find to be
700 // empty might not yet be added to the free list. It is not straightforward
701 // to know in which list they are on so that we can remove them. We only
702 // need to do this if we need to allocate more than one region to satisfy the
703 // current humongous allocation request. If we are only allocating one region
704 // we use the one-region region allocation code (see above), that already
705 // potentially waits for regions from the secondary free list.
706 wait_while_free_regions_coming();
707 append_secondary_free_list_if_not_empty_with_lock();
708
709 // Policy: Try only empty regions (i.e. already committed first). Maybe we
710 // are lucky enough to find some.
711 first = _hrm.find_contiguous_only_empty(obj_regions);
712 if (first != G1_NO_HRM_INDEX) {
713 _hrm.allocate_free_regions_starting_at(first, obj_regions);
714 }
715 }
716
717 if (first == G1_NO_HRM_INDEX) {
718 // Policy: We could not find enough regions for the humongous object in the
719 // free list. Look through the heap to find a mix of free and uncommitted regions.
720 // If so, try expansion.
721 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
722 if (first != G1_NO_HRM_INDEX) {
723 // We found something. Make sure these regions are committed, i.e. expand
724 // the heap. Alternatively we could do a defragmentation GC.
725 ergo_verbose1(ErgoHeapSizing,
726 "attempt heap expansion",
727 ergo_format_reason("humongous allocation request failed")
728 ergo_format_byte("allocation request"),
729 word_size * HeapWordSize);
730
731 _hrm.expand_at(first, obj_regions);
732 g1_policy()->record_new_heap_size(num_regions());
733
734 #ifdef ASSERT
735 for (uint i = first; i < first + obj_regions; ++i) {
736 HeapRegion* hr = region_at(i);
737 assert(hr->is_free(), "sanity");
738 assert(hr->is_empty(), "sanity");
739 assert(is_on_master_free_list(hr), "sanity");
740 }
741 #endif
742 _hrm.allocate_free_regions_starting_at(first, obj_regions);
743 } else {
744 // Policy: Potentially trigger a defragmentation GC.
745 }
746 }
747
748 HeapWord* result = NULL;
749 if (first != G1_NO_HRM_INDEX) {
750 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
751 word_size, context);
752 assert(result != NULL, "it should always return a valid result");
753
754 // A successful humongous object allocation changes the used space
755 // information of the old generation so we need to recalculate the
756 // sizes and update the jstat counters here.
757 g1mm()->update_sizes();
758 }
759
760 verify_region_sets_optional();
761
762 return result;
763 }
764
765 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
766 assert_heap_not_locked_and_not_at_safepoint();
767 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
768
769 uint dummy_gc_count_before;
770 uint dummy_gclocker_retry_count = 0;
771 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
772 }
773
774 HeapWord*
775 G1CollectedHeap::mem_allocate(size_t word_size,
776 bool* gc_overhead_limit_was_exceeded) {
777 assert_heap_not_locked_and_not_at_safepoint();
778
779 // Loop until the allocation is satisfied, or unsatisfied after GC.
780 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
781 uint gc_count_before;
782
783 HeapWord* result = NULL;
784 if (!is_humongous(word_size)) {
785 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
786 } else {
787 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
788 }
789 if (result != NULL) {
790 return result;
791 }
792
793 // Create the garbage collection operation...
794 VM_G1CollectForAllocation op(gc_count_before, word_size);
795 op.set_allocation_context(AllocationContext::current());
796
797 // ...and get the VM thread to execute it.
798 VMThread::execute(&op);
799
800 if (op.prologue_succeeded() && op.pause_succeeded()) {
801 // If the operation was successful we'll return the result even
802 // if it is NULL. If the allocation attempt failed immediately
803 // after a Full GC, it's unlikely we'll be able to allocate now.
804 HeapWord* result = op.result();
805 if (result != NULL && !is_humongous(word_size)) {
806 // Allocations that take place on VM operations do not do any
807 // card dirtying and we have to do it here. We only have to do
808 // this for non-humongous allocations, though.
809 dirty_young_block(result, word_size);
810 }
811 return result;
812 } else {
813 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
814 return NULL;
815 }
816 assert(op.result() == NULL,
817 "the result should be NULL if the VM op did not succeed");
818 }
819
820 // Give a warning if we seem to be looping forever.
821 if ((QueuedAllocationWarningCount > 0) &&
822 (try_count % QueuedAllocationWarningCount == 0)) {
823 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
824 }
825 }
826
827 ShouldNotReachHere();
828 return NULL;
829 }
830
831 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
832 AllocationContext_t context,
833 uint* gc_count_before_ret,
834 uint* gclocker_retry_count_ret) {
835 // Make sure you read the note in attempt_allocation_humongous().
836
837 assert_heap_not_locked_and_not_at_safepoint();
838 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
839 "be called for humongous allocation requests");
840
841 // We should only get here after the first-level allocation attempt
842 // (attempt_allocation()) failed to allocate.
843
844 // We will loop until a) we manage to successfully perform the
845 // allocation or b) we successfully schedule a collection which
846 // fails to perform the allocation. b) is the only case when we'll
847 // return NULL.
848 HeapWord* result = NULL;
849 for (int try_count = 1; /* we'll return */; try_count += 1) {
850 bool should_try_gc;
851 uint gc_count_before;
852
853 {
854 MutexLockerEx x(Heap_lock);
855 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
856 false /* bot_updates */);
857 if (result != NULL) {
858 return result;
859 }
860
861 // If we reach here, attempt_allocation_locked() above failed to
862 // allocate a new region. So the mutator alloc region should be NULL.
863 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
864
865 if (GC_locker::is_active_and_needs_gc()) {
866 if (g1_policy()->can_expand_young_list()) {
867 // No need for an ergo verbose message here,
868 // can_expand_young_list() does this when it returns true.
869 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
870 false /* bot_updates */);
871 if (result != NULL) {
872 return result;
873 }
874 }
875 should_try_gc = false;
876 } else {
877 // The GCLocker may not be active but the GCLocker initiated
878 // GC may not yet have been performed (GCLocker::needs_gc()
879 // returns true). In this case we do not try this GC and
880 // wait until the GCLocker initiated GC is performed, and
881 // then retry the allocation.
882 if (GC_locker::needs_gc()) {
883 should_try_gc = false;
884 } else {
885 // Read the GC count while still holding the Heap_lock.
886 gc_count_before = total_collections();
887 should_try_gc = true;
888 }
889 }
890 }
891
892 if (should_try_gc) {
893 bool succeeded;
894 result = do_collection_pause(word_size, gc_count_before, &succeeded,
895 GCCause::_g1_inc_collection_pause);
896 if (result != NULL) {
897 assert(succeeded, "only way to get back a non-NULL result");
898 return result;
899 }
900
901 if (succeeded) {
902 // If we get here we successfully scheduled a collection which
903 // failed to allocate. No point in trying to allocate
904 // further. We'll just return NULL.
905 MutexLockerEx x(Heap_lock);
906 *gc_count_before_ret = total_collections();
907 return NULL;
908 }
909 } else {
910 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
911 MutexLockerEx x(Heap_lock);
912 *gc_count_before_ret = total_collections();
913 return NULL;
914 }
915 // The GCLocker is either active or the GCLocker initiated
916 // GC has not yet been performed. Stall until it is and
917 // then retry the allocation.
918 GC_locker::stall_until_clear();
919 (*gclocker_retry_count_ret) += 1;
920 }
921
922 // We can reach here if we were unsuccessful in scheduling a
923 // collection (because another thread beat us to it) or if we were
924 // stalled due to the GC locker. In either can we should retry the
925 // allocation attempt in case another thread successfully
926 // performed a collection and reclaimed enough space. We do the
927 // first attempt (without holding the Heap_lock) here and the
928 // follow-on attempt will be at the start of the next loop
929 // iteration (after taking the Heap_lock).
930 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
931 false /* bot_updates */);
932 if (result != NULL) {
933 return result;
934 }
935
936 // Give a warning if we seem to be looping forever.
937 if ((QueuedAllocationWarningCount > 0) &&
938 (try_count % QueuedAllocationWarningCount == 0)) {
939 warning("G1CollectedHeap::attempt_allocation_slow() "
940 "retries %d times", try_count);
941 }
942 }
943
944 ShouldNotReachHere();
945 return NULL;
946 }
947
948 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
949 uint* gc_count_before_ret,
950 uint* gclocker_retry_count_ret) {
951 // The structure of this method has a lot of similarities to
952 // attempt_allocation_slow(). The reason these two were not merged
953 // into a single one is that such a method would require several "if
954 // allocation is not humongous do this, otherwise do that"
955 // conditional paths which would obscure its flow. In fact, an early
956 // version of this code did use a unified method which was harder to
957 // follow and, as a result, it had subtle bugs that were hard to
958 // track down. So keeping these two methods separate allows each to
959 // be more readable. It will be good to keep these two in sync as
960 // much as possible.
961
962 assert_heap_not_locked_and_not_at_safepoint();
963 assert(is_humongous(word_size), "attempt_allocation_humongous() "
964 "should only be called for humongous allocations");
965
966 // Humongous objects can exhaust the heap quickly, so we should check if we
967 // need to start a marking cycle at each humongous object allocation. We do
968 // the check before we do the actual allocation. The reason for doing it
969 // before the allocation is that we avoid having to keep track of the newly
970 // allocated memory while we do a GC.
971 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
972 word_size)) {
973 collect(GCCause::_g1_humongous_allocation);
974 }
975
976 // We will loop until a) we manage to successfully perform the
977 // allocation or b) we successfully schedule a collection which
978 // fails to perform the allocation. b) is the only case when we'll
979 // return NULL.
980 HeapWord* result = NULL;
981 for (int try_count = 1; /* we'll return */; try_count += 1) {
982 bool should_try_gc;
983 uint gc_count_before;
984
985 {
986 MutexLockerEx x(Heap_lock);
987
988 // Given that humongous objects are not allocated in young
989 // regions, we'll first try to do the allocation without doing a
990 // collection hoping that there's enough space in the heap.
991 result = humongous_obj_allocate(word_size, AllocationContext::current());
992 if (result != NULL) {
993 return result;
994 }
995
996 if (GC_locker::is_active_and_needs_gc()) {
997 should_try_gc = false;
998 } else {
999 // The GCLocker may not be active but the GCLocker initiated
1000 // GC may not yet have been performed (GCLocker::needs_gc()
1001 // returns true). In this case we do not try this GC and
1002 // wait until the GCLocker initiated GC is performed, and
1003 // then retry the allocation.
1004 if (GC_locker::needs_gc()) {
1005 should_try_gc = false;
1006 } else {
1007 // Read the GC count while still holding the Heap_lock.
1008 gc_count_before = total_collections();
1009 should_try_gc = true;
1010 }
1011 }
1012 }
1013
1014 if (should_try_gc) {
1015 // If we failed to allocate the humongous object, we should try to
1016 // do a collection pause (if we're allowed) in case it reclaims
1017 // enough space for the allocation to succeed after the pause.
1018
1019 bool succeeded;
1020 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1021 GCCause::_g1_humongous_allocation);
1022 if (result != NULL) {
1023 assert(succeeded, "only way to get back a non-NULL result");
1024 return result;
1025 }
1026
1027 if (succeeded) {
1028 // If we get here we successfully scheduled a collection which
1029 // failed to allocate. No point in trying to allocate
1030 // further. We'll just return NULL.
1031 MutexLockerEx x(Heap_lock);
1032 *gc_count_before_ret = total_collections();
1033 return NULL;
1034 }
1035 } else {
1036 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1037 MutexLockerEx x(Heap_lock);
1038 *gc_count_before_ret = total_collections();
1039 return NULL;
1040 }
1041 // The GCLocker is either active or the GCLocker initiated
1042 // GC has not yet been performed. Stall until it is and
1043 // then retry the allocation.
1044 GC_locker::stall_until_clear();
1045 (*gclocker_retry_count_ret) += 1;
1046 }
1047
1048 // We can reach here if we were unsuccessful in scheduling a
1049 // collection (because another thread beat us to it) or if we were
1050 // stalled due to the GC locker. In either can we should retry the
1051 // allocation attempt in case another thread successfully
1052 // performed a collection and reclaimed enough space. Give a
1053 // warning if we seem to be looping forever.
1054
1055 if ((QueuedAllocationWarningCount > 0) &&
1056 (try_count % QueuedAllocationWarningCount == 0)) {
1057 warning("G1CollectedHeap::attempt_allocation_humongous() "
1058 "retries %d times", try_count);
1059 }
1060 }
1061
1062 ShouldNotReachHere();
1063 return NULL;
1064 }
1065
1066 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1067 AllocationContext_t context,
1068 bool expect_null_mutator_alloc_region) {
1069 assert_at_safepoint(true /* should_be_vm_thread */);
1070 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1071 !expect_null_mutator_alloc_region,
1072 "the current alloc region was unexpectedly found to be non-NULL");
1073
1074 if (!is_humongous(word_size)) {
1075 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1076 false /* bot_updates */);
1077 } else {
1078 HeapWord* result = humongous_obj_allocate(word_size, context);
1079 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1080 g1_policy()->set_initiate_conc_mark_if_possible();
1081 }
1082 return result;
1083 }
1084
1085 ShouldNotReachHere();
1086 }
1087
1088 class PostMCRemSetClearClosure: public HeapRegionClosure {
1089 G1CollectedHeap* _g1h;
1090 ModRefBarrierSet* _mr_bs;
1091 public:
1092 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1093 _g1h(g1h), _mr_bs(mr_bs) {}
1094
1095 bool doHeapRegion(HeapRegion* r) {
1096 HeapRegionRemSet* hrrs = r->rem_set();
1097
1098 if (r->is_continues_humongous()) {
1099 // We'll assert that the strong code root list and RSet is empty
1100 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1101 assert(hrrs->occupied() == 0, "RSet should be empty");
1102 return false;
1103 }
1104
1105 _g1h->reset_gc_time_stamps(r);
1106 hrrs->clear();
1107 // You might think here that we could clear just the cards
1108 // corresponding to the used region. But no: if we leave a dirty card
1109 // in a region we might allocate into, then it would prevent that card
1110 // from being enqueued, and cause it to be missed.
1111 // Re: the performance cost: we shouldn't be doing full GC anyway!
1112 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1113
1114 return false;
1115 }
1116 };
1117
1118 void G1CollectedHeap::clear_rsets_post_compaction() {
1119 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1120 heap_region_iterate(&rs_clear);
1121 }
1122
1123 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1124 G1CollectedHeap* _g1h;
1125 UpdateRSOopClosure _cl;
1126 int _worker_i;
1127 public:
1128 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1129 _cl(g1->g1_rem_set(), worker_i),
1130 _worker_i(worker_i),
1131 _g1h(g1)
1132 { }
1133
1134 bool doHeapRegion(HeapRegion* r) {
1135 if (!r->is_continues_humongous()) {
1136 _cl.set_from(r);
1137 r->oop_iterate(&_cl);
1138 }
1139 return false;
1140 }
1141 };
1142
1143 class ParRebuildRSTask: public AbstractGangTask {
1144 G1CollectedHeap* _g1;
1145 HeapRegionClaimer _hrclaimer;
1146
1147 public:
1148 ParRebuildRSTask(G1CollectedHeap* g1) :
1149 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1150
1151 void work(uint worker_id) {
1152 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1153 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1154 }
1155 };
1156
1157 class PostCompactionPrinterClosure: public HeapRegionClosure {
1158 private:
1159 G1HRPrinter* _hr_printer;
1160 public:
1161 bool doHeapRegion(HeapRegion* hr) {
1162 assert(!hr->is_young(), "not expecting to find young regions");
1163 if (hr->is_free()) {
1164 // We only generate output for non-empty regions.
1165 } else if (hr->is_starts_humongous()) {
1166 if (hr->region_num() == 1) {
1167 // single humongous region
1168 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1169 } else {
1170 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1171 }
1172 } else if (hr->is_continues_humongous()) {
1173 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1174 } else if (hr->is_old()) {
1175 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1176 } else {
1177 ShouldNotReachHere();
1178 }
1179 return false;
1180 }
1181
1182 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1183 : _hr_printer(hr_printer) { }
1184 };
1185
1186 void G1CollectedHeap::print_hrm_post_compaction() {
1187 PostCompactionPrinterClosure cl(hr_printer());
1188 heap_region_iterate(&cl);
1189 }
1190
1191 bool G1CollectedHeap::do_collection(bool explicit_gc,
1192 bool clear_all_soft_refs,
1193 size_t word_size) {
1194 assert_at_safepoint(true /* should_be_vm_thread */);
1195
1196 if (GC_locker::check_active_before_gc()) {
1197 return false;
1198 }
1199
1200 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1201 gc_timer->register_gc_start();
1202
1203 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1204 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1205
1206 SvcGCMarker sgcm(SvcGCMarker::FULL);
1207 ResourceMark rm;
1208
1209 print_heap_before_gc();
1210 trace_heap_before_gc(gc_tracer);
1211
1212 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1213
1214 verify_region_sets_optional();
1215
1216 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1217 collector_policy()->should_clear_all_soft_refs();
1218
1219 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1220
1221 {
1222 IsGCActiveMark x;
1223
1224 // Timing
1225 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1226 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1227
1228 {
1229 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1230 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1231 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1232
1233 g1_policy()->record_full_collection_start();
1234
1235 // Note: When we have a more flexible GC logging framework that
1236 // allows us to add optional attributes to a GC log record we
1237 // could consider timing and reporting how long we wait in the
1238 // following two methods.
1239 wait_while_free_regions_coming();
1240 // If we start the compaction before the CM threads finish
1241 // scanning the root regions we might trip them over as we'll
1242 // be moving objects / updating references. So let's wait until
1243 // they are done. By telling them to abort, they should complete
1244 // early.
1245 _cm->root_regions()->abort();
1246 _cm->root_regions()->wait_until_scan_finished();
1247 append_secondary_free_list_if_not_empty_with_lock();
1248
1249 gc_prologue(true);
1250 increment_total_collections(true /* full gc */);
1251 increment_old_marking_cycles_started();
1252
1253 assert(used() == recalculate_used(), "Should be equal");
1254
1255 verify_before_gc();
1256
1257 check_bitmaps("Full GC Start");
1258 pre_full_gc_dump(gc_timer);
1259
1260 COMPILER2_PRESENT(DerivedPointerTable::clear());
1261
1262 // Disable discovery and empty the discovered lists
1263 // for the CM ref processor.
1264 ref_processor_cm()->disable_discovery();
1265 ref_processor_cm()->abandon_partial_discovery();
1266 ref_processor_cm()->verify_no_references_recorded();
1267
1268 // Abandon current iterations of concurrent marking and concurrent
1269 // refinement, if any are in progress. We have to do this before
1270 // wait_until_scan_finished() below.
1271 concurrent_mark()->abort();
1272
1273 // Make sure we'll choose a new allocation region afterwards.
1274 _allocator->release_mutator_alloc_region();
1275 _allocator->abandon_gc_alloc_regions();
1276 g1_rem_set()->cleanupHRRS();
1277
1278 // We should call this after we retire any currently active alloc
1279 // regions so that all the ALLOC / RETIRE events are generated
1280 // before the start GC event.
1281 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1282
1283 // We may have added regions to the current incremental collection
1284 // set between the last GC or pause and now. We need to clear the
1285 // incremental collection set and then start rebuilding it afresh
1286 // after this full GC.
1287 abandon_collection_set(g1_policy()->inc_cset_head());
1288 g1_policy()->clear_incremental_cset();
1289 g1_policy()->stop_incremental_cset_building();
1290
1291 tear_down_region_sets(false /* free_list_only */);
1292 g1_policy()->set_gcs_are_young(true);
1293
1294 // See the comments in g1CollectedHeap.hpp and
1295 // G1CollectedHeap::ref_processing_init() about
1296 // how reference processing currently works in G1.
1297
1298 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1299 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1300
1301 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1302 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1303
1304 ref_processor_stw()->enable_discovery();
1305 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1306
1307 // Do collection work
1308 {
1309 HandleMark hm; // Discard invalid handles created during gc
1310 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1311 }
1312
1313 assert(num_free_regions() == 0, "we should not have added any free regions");
1314 rebuild_region_sets(false /* free_list_only */);
1315
1316 // Enqueue any discovered reference objects that have
1317 // not been removed from the discovered lists.
1318 ref_processor_stw()->enqueue_discovered_references();
1319
1320 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1321
1322 MemoryService::track_memory_usage();
1323
1324 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1325 ref_processor_stw()->verify_no_references_recorded();
1326
1327 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1328 ClassLoaderDataGraph::purge();
1329 MetaspaceAux::verify_metrics();
1330
1331 // Note: since we've just done a full GC, concurrent
1332 // marking is no longer active. Therefore we need not
1333 // re-enable reference discovery for the CM ref processor.
1334 // That will be done at the start of the next marking cycle.
1335 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1336 ref_processor_cm()->verify_no_references_recorded();
1337
1338 reset_gc_time_stamp();
1339 // Since everything potentially moved, we will clear all remembered
1340 // sets, and clear all cards. Later we will rebuild remembered
1341 // sets. We will also reset the GC time stamps of the regions.
1342 clear_rsets_post_compaction();
1343 check_gc_time_stamps();
1344
1345 // Resize the heap if necessary.
1346 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1347
1348 if (_hr_printer.is_active()) {
1349 // We should do this after we potentially resize the heap so
1350 // that all the COMMIT / UNCOMMIT events are generated before
1351 // the end GC event.
1352
1353 print_hrm_post_compaction();
1354 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1355 }
1356
1357 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1358 if (hot_card_cache->use_cache()) {
1359 hot_card_cache->reset_card_counts();
1360 hot_card_cache->reset_hot_cache();
1361 }
1362
1363 // Rebuild remembered sets of all regions.
1364 uint n_workers =
1365 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1366 workers()->active_workers(),
1367 Threads::number_of_non_daemon_threads());
1368 assert(UseDynamicNumberOfGCThreads ||
1369 n_workers == workers()->total_workers(),
1370 "If not dynamic should be using all the workers");
1371 workers()->set_active_workers(n_workers);
1372 // Set parallel threads in the heap (_n_par_threads) only
1373 // before a parallel phase and always reset it to 0 after
1374 // the phase so that the number of parallel threads does
1375 // no get carried forward to a serial phase where there
1376 // may be code that is "possibly_parallel".
1377 set_par_threads(n_workers);
1378
1379 ParRebuildRSTask rebuild_rs_task(this);
1380 assert(UseDynamicNumberOfGCThreads ||
1381 workers()->active_workers() == workers()->total_workers(),
1382 "Unless dynamic should use total workers");
1383 // Use the most recent number of active workers
1384 assert(workers()->active_workers() > 0,
1385 "Active workers not properly set");
1386 set_par_threads(workers()->active_workers());
1387 workers()->run_task(&rebuild_rs_task);
1388 set_par_threads(0);
1389
1390 // Rebuild the strong code root lists for each region
1391 rebuild_strong_code_roots();
1392
1393 if (true) { // FIXME
1394 MetaspaceGC::compute_new_size();
1395 }
1396
1397 #ifdef TRACESPINNING
1398 ParallelTaskTerminator::print_termination_counts();
1399 #endif
1400
1401 // Discard all rset updates
1402 JavaThread::dirty_card_queue_set().abandon_logs();
1403 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1404
1405 _young_list->reset_sampled_info();
1406 // At this point there should be no regions in the
1407 // entire heap tagged as young.
1408 assert(check_young_list_empty(true /* check_heap */),
1409 "young list should be empty at this point");
1410
1411 // Update the number of full collections that have been completed.
1412 increment_old_marking_cycles_completed(false /* concurrent */);
1413
1414 _hrm.verify_optional();
1415 verify_region_sets_optional();
1416
1417 verify_after_gc();
1418
1419 // Clear the previous marking bitmap, if needed for bitmap verification.
1420 // Note we cannot do this when we clear the next marking bitmap in
1421 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1422 // objects marked during a full GC against the previous bitmap.
1423 // But we need to clear it before calling check_bitmaps below since
1424 // the full GC has compacted objects and updated TAMS but not updated
1425 // the prev bitmap.
1426 if (G1VerifyBitmaps) {
1427 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1428 }
1429 check_bitmaps("Full GC End");
1430
1431 // Start a new incremental collection set for the next pause
1432 assert(g1_policy()->collection_set() == NULL, "must be");
1433 g1_policy()->start_incremental_cset_building();
1434
1435 clear_cset_fast_test();
1436
1437 _allocator->init_mutator_alloc_region();
1438
1439 g1_policy()->record_full_collection_end();
1440
1441 if (G1Log::fine()) {
1442 g1_policy()->print_heap_transition();
1443 }
1444
1445 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1446 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1447 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1448 // before any GC notifications are raised.
1449 g1mm()->update_sizes();
1450
1451 gc_epilogue(true);
1452 }
1453
1454 if (G1Log::finer()) {
1455 g1_policy()->print_detailed_heap_transition(true /* full */);
1456 }
1457
1458 print_heap_after_gc();
1459 trace_heap_after_gc(gc_tracer);
1460
1461 post_full_gc_dump(gc_timer);
1462
1463 gc_timer->register_gc_end();
1464 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1465 }
1466
1467 return true;
1468 }
1469
1470 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1471 // do_collection() will return whether it succeeded in performing
1472 // the GC. Currently, there is no facility on the
1473 // do_full_collection() API to notify the caller than the collection
1474 // did not succeed (e.g., because it was locked out by the GC
1475 // locker). So, right now, we'll ignore the return value.
1476 bool dummy = do_collection(true, /* explicit_gc */
1477 clear_all_soft_refs,
1478 0 /* word_size */);
1479 }
1480
1481 // This code is mostly copied from TenuredGeneration.
1482 void
1483 G1CollectedHeap::
1484 resize_if_necessary_after_full_collection(size_t word_size) {
1485 // Include the current allocation, if any, and bytes that will be
1486 // pre-allocated to support collections, as "used".
1487 const size_t used_after_gc = used();
1488 const size_t capacity_after_gc = capacity();
1489 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1490
1491 // This is enforced in arguments.cpp.
1492 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1493 "otherwise the code below doesn't make sense");
1494
1495 // We don't have floating point command-line arguments
1496 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1497 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1498 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1499 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1500
1501 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1502 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1503
1504 // We have to be careful here as these two calculations can overflow
1505 // 32-bit size_t's.
1506 double used_after_gc_d = (double) used_after_gc;
1507 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1508 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1509
1510 // Let's make sure that they are both under the max heap size, which
1511 // by default will make them fit into a size_t.
1512 double desired_capacity_upper_bound = (double) max_heap_size;
1513 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1514 desired_capacity_upper_bound);
1515 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1516 desired_capacity_upper_bound);
1517
1518 // We can now safely turn them into size_t's.
1519 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1520 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1521
1522 // This assert only makes sense here, before we adjust them
1523 // with respect to the min and max heap size.
1524 assert(minimum_desired_capacity <= maximum_desired_capacity,
1525 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1526 "maximum_desired_capacity = "SIZE_FORMAT,
1527 minimum_desired_capacity, maximum_desired_capacity));
1528
1529 // Should not be greater than the heap max size. No need to adjust
1530 // it with respect to the heap min size as it's a lower bound (i.e.,
1531 // we'll try to make the capacity larger than it, not smaller).
1532 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1533 // Should not be less than the heap min size. No need to adjust it
1534 // with respect to the heap max size as it's an upper bound (i.e.,
1535 // we'll try to make the capacity smaller than it, not greater).
1536 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1537
1538 if (capacity_after_gc < minimum_desired_capacity) {
1539 // Don't expand unless it's significant
1540 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1541 ergo_verbose4(ErgoHeapSizing,
1542 "attempt heap expansion",
1543 ergo_format_reason("capacity lower than "
1544 "min desired capacity after Full GC")
1545 ergo_format_byte("capacity")
1546 ergo_format_byte("occupancy")
1547 ergo_format_byte_perc("min desired capacity"),
1548 capacity_after_gc, used_after_gc,
1549 minimum_desired_capacity, (double) MinHeapFreeRatio);
1550 expand(expand_bytes);
1551
1552 // No expansion, now see if we want to shrink
1553 } else if (capacity_after_gc > maximum_desired_capacity) {
1554 // Capacity too large, compute shrinking size
1555 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1556 ergo_verbose4(ErgoHeapSizing,
1557 "attempt heap shrinking",
1558 ergo_format_reason("capacity higher than "
1559 "max desired capacity after Full GC")
1560 ergo_format_byte("capacity")
1561 ergo_format_byte("occupancy")
1562 ergo_format_byte_perc("max desired capacity"),
1563 capacity_after_gc, used_after_gc,
1564 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1565 shrink(shrink_bytes);
1566 }
1567 }
1568
1569
1570 HeapWord*
1571 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1572 AllocationContext_t context,
1573 bool* succeeded) {
1574 assert_at_safepoint(true /* should_be_vm_thread */);
1575
1576 *succeeded = true;
1577 // Let's attempt the allocation first.
1578 HeapWord* result =
1579 attempt_allocation_at_safepoint(word_size,
1580 context,
1581 false /* expect_null_mutator_alloc_region */);
1582 if (result != NULL) {
1583 assert(*succeeded, "sanity");
1584 return result;
1585 }
1586
1587 // In a G1 heap, we're supposed to keep allocation from failing by
1588 // incremental pauses. Therefore, at least for now, we'll favor
1589 // expansion over collection. (This might change in the future if we can
1590 // do something smarter than full collection to satisfy a failed alloc.)
1591 result = expand_and_allocate(word_size, context);
1592 if (result != NULL) {
1593 assert(*succeeded, "sanity");
1594 return result;
1595 }
1596
1597 // Expansion didn't work, we'll try to do a Full GC.
1598 bool gc_succeeded = do_collection(false, /* explicit_gc */
1599 false, /* clear_all_soft_refs */
1600 word_size);
1601 if (!gc_succeeded) {
1602 *succeeded = false;
1603 return NULL;
1604 }
1605
1606 // Retry the allocation
1607 result = attempt_allocation_at_safepoint(word_size,
1608 context,
1609 true /* expect_null_mutator_alloc_region */);
1610 if (result != NULL) {
1611 assert(*succeeded, "sanity");
1612 return result;
1613 }
1614
1615 // Then, try a Full GC that will collect all soft references.
1616 gc_succeeded = do_collection(false, /* explicit_gc */
1617 true, /* clear_all_soft_refs */
1618 word_size);
1619 if (!gc_succeeded) {
1620 *succeeded = false;
1621 return NULL;
1622 }
1623
1624 // Retry the allocation once more
1625 result = attempt_allocation_at_safepoint(word_size,
1626 context,
1627 true /* expect_null_mutator_alloc_region */);
1628 if (result != NULL) {
1629 assert(*succeeded, "sanity");
1630 return result;
1631 }
1632
1633 assert(!collector_policy()->should_clear_all_soft_refs(),
1634 "Flag should have been handled and cleared prior to this point");
1635
1636 // What else? We might try synchronous finalization later. If the total
1637 // space available is large enough for the allocation, then a more
1638 // complete compaction phase than we've tried so far might be
1639 // appropriate.
1640 assert(*succeeded, "sanity");
1641 return NULL;
1642 }
1643
1644 // Attempting to expand the heap sufficiently
1645 // to support an allocation of the given "word_size". If
1646 // successful, perform the allocation and return the address of the
1647 // allocated block, or else "NULL".
1648
1649 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1650 assert_at_safepoint(true /* should_be_vm_thread */);
1651
1652 verify_region_sets_optional();
1653
1654 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1655 ergo_verbose1(ErgoHeapSizing,
1656 "attempt heap expansion",
1657 ergo_format_reason("allocation request failed")
1658 ergo_format_byte("allocation request"),
1659 word_size * HeapWordSize);
1660 if (expand(expand_bytes)) {
1661 _hrm.verify_optional();
1662 verify_region_sets_optional();
1663 return attempt_allocation_at_safepoint(word_size,
1664 context,
1665 false /* expect_null_mutator_alloc_region */);
1666 }
1667 return NULL;
1668 }
1669
1670 bool G1CollectedHeap::expand(size_t expand_bytes) {
1671 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1672 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1673 HeapRegion::GrainBytes);
1674 ergo_verbose2(ErgoHeapSizing,
1675 "expand the heap",
1676 ergo_format_byte("requested expansion amount")
1677 ergo_format_byte("attempted expansion amount"),
1678 expand_bytes, aligned_expand_bytes);
1679
1680 if (is_maximal_no_gc()) {
1681 ergo_verbose0(ErgoHeapSizing,
1682 "did not expand the heap",
1683 ergo_format_reason("heap already fully expanded"));
1684 return false;
1685 }
1686
1687 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1688 assert(regions_to_expand > 0, "Must expand by at least one region");
1689
1690 uint expanded_by = _hrm.expand_by(regions_to_expand);
1691
1692 if (expanded_by > 0) {
1693 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1694 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1695 g1_policy()->record_new_heap_size(num_regions());
1696 } else {
1697 ergo_verbose0(ErgoHeapSizing,
1698 "did not expand the heap",
1699 ergo_format_reason("heap expansion operation failed"));
1700 // The expansion of the virtual storage space was unsuccessful.
1701 // Let's see if it was because we ran out of swap.
1702 if (G1ExitOnExpansionFailure &&
1703 _hrm.available() >= regions_to_expand) {
1704 // We had head room...
1705 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1706 }
1707 }
1708 return regions_to_expand > 0;
1709 }
1710
1711 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1712 size_t aligned_shrink_bytes =
1713 ReservedSpace::page_align_size_down(shrink_bytes);
1714 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1715 HeapRegion::GrainBytes);
1716 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1717
1718 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1719 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1720
1721 ergo_verbose3(ErgoHeapSizing,
1722 "shrink the heap",
1723 ergo_format_byte("requested shrinking amount")
1724 ergo_format_byte("aligned shrinking amount")
1725 ergo_format_byte("attempted shrinking amount"),
1726 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1727 if (num_regions_removed > 0) {
1728 g1_policy()->record_new_heap_size(num_regions());
1729 } else {
1730 ergo_verbose0(ErgoHeapSizing,
1731 "did not shrink the heap",
1732 ergo_format_reason("heap shrinking operation failed"));
1733 }
1734 }
1735
1736 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1737 verify_region_sets_optional();
1738
1739 // We should only reach here at the end of a Full GC which means we
1740 // should not not be holding to any GC alloc regions. The method
1741 // below will make sure of that and do any remaining clean up.
1742 _allocator->abandon_gc_alloc_regions();
1743
1744 // Instead of tearing down / rebuilding the free lists here, we
1745 // could instead use the remove_all_pending() method on free_list to
1746 // remove only the ones that we need to remove.
1747 tear_down_region_sets(true /* free_list_only */);
1748 shrink_helper(shrink_bytes);
1749 rebuild_region_sets(true /* free_list_only */);
1750
1751 _hrm.verify_optional();
1752 verify_region_sets_optional();
1753 }
1754
1755 // Public methods.
1756
1757 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1758 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1759 #endif // _MSC_VER
1760
1761
1762 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1763 SharedHeap(policy_),
1764 _g1_policy(policy_),
1765 _dirty_card_queue_set(false),
1766 _into_cset_dirty_card_queue_set(false),
1767 _is_alive_closure_cm(this),
1768 _is_alive_closure_stw(this),
1769 _ref_processor_cm(NULL),
1770 _ref_processor_stw(NULL),
1771 _bot_shared(NULL),
1772 _evac_failure_scan_stack(NULL),
1773 _mark_in_progress(false),
1774 _cg1r(NULL),
1775 _g1mm(NULL),
1776 _refine_cte_cl(NULL),
1777 _full_collection(false),
1778 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1779 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1780 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1781 _humongous_is_live(),
1782 _has_humongous_reclaim_candidates(false),
1783 _free_regions_coming(false),
1784 _young_list(new YoungList(this)),
1785 _gc_time_stamp(0),
1786 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1787 _old_plab_stats(OldPLABSize, PLABWeight),
1788 _expand_heap_after_alloc_failure(true),
1789 _surviving_young_words(NULL),
1790 _old_marking_cycles_started(0),
1791 _old_marking_cycles_completed(0),
1792 _concurrent_cycle_started(false),
1793 _heap_summary_sent(false),
1794 _in_cset_fast_test(),
1795 _dirty_cards_region_list(NULL),
1796 _worker_cset_start_region(NULL),
1797 _worker_cset_start_region_time_stamp(NULL),
1798 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1799 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1800 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1801 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1802
1803 _g1h = this;
1804
1805 _allocator = G1Allocator::create_allocator(_g1h);
1806 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1807
1808 int n_queues = MAX2((int)ParallelGCThreads, 1);
1809 _task_queues = new RefToScanQueueSet(n_queues);
1810
1811 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1812 assert(n_rem_sets > 0, "Invariant.");
1813
1814 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1815 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1816 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1817
1818 for (int i = 0; i < n_queues; i++) {
1819 RefToScanQueue* q = new RefToScanQueue();
1820 q->initialize();
1821 _task_queues->register_queue(i, q);
1822 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1823 }
1824 clear_cset_start_regions();
1825
1826 // Initialize the G1EvacuationFailureALot counters and flags.
1827 NOT_PRODUCT(reset_evacuation_should_fail();)
1828
1829 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1830 }
1831
1832 jint G1CollectedHeap::initialize() {
1833 CollectedHeap::pre_initialize();
1834 os::enable_vtime();
1835
1836 G1Log::init();
1837
1838 // Necessary to satisfy locking discipline assertions.
1839
1840 MutexLocker x(Heap_lock);
1841
1842 // We have to initialize the printer before committing the heap, as
1843 // it will be used then.
1844 _hr_printer.set_active(G1PrintHeapRegions);
1845
1846 // While there are no constraints in the GC code that HeapWordSize
1847 // be any particular value, there are multiple other areas in the
1848 // system which believe this to be true (e.g. oop->object_size in some
1849 // cases incorrectly returns the size in wordSize units rather than
1850 // HeapWordSize).
1851 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1852
1853 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1854 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1855 size_t heap_alignment = collector_policy()->heap_alignment();
1856
1857 // Ensure that the sizes are properly aligned.
1858 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1859 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1860 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1861
1862 _refine_cte_cl = new RefineCardTableEntryClosure();
1863
1864 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1865
1866 // Reserve the maximum.
1867
1868 // When compressed oops are enabled, the preferred heap base
1869 // is calculated by subtracting the requested size from the
1870 // 32Gb boundary and using the result as the base address for
1871 // heap reservation. If the requested size is not aligned to
1872 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1873 // into the ReservedHeapSpace constructor) then the actual
1874 // base of the reserved heap may end up differing from the
1875 // address that was requested (i.e. the preferred heap base).
1876 // If this happens then we could end up using a non-optimal
1877 // compressed oops mode.
1878
1879 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1880 heap_alignment);
1881
1882 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1883
1884 // Create the barrier set for the entire reserved region.
1885 G1SATBCardTableLoggingModRefBS* bs
1886 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1887 bs->initialize();
1888 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1889 set_barrier_set(bs);
1890
1891 // Also create a G1 rem set.
1892 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1893
1894 // Carve out the G1 part of the heap.
1895
1896 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1897 G1RegionToSpaceMapper* heap_storage =
1898 G1RegionToSpaceMapper::create_mapper(g1_rs,
1899 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1900 HeapRegion::GrainBytes,
1901 1,
1902 mtJavaHeap);
1903 heap_storage->set_mapping_changed_listener(&_listener);
1904
1905 // Reserve space for the block offset table. We do not support automatic uncommit
1906 // for the card table at this time. BOT only.
1907 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1908 G1RegionToSpaceMapper* bot_storage =
1909 G1RegionToSpaceMapper::create_mapper(bot_rs,
1910 os::vm_page_size(),
1911 HeapRegion::GrainBytes,
1912 G1BlockOffsetSharedArray::N_bytes,
1913 mtGC);
1914
1915 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1916 G1RegionToSpaceMapper* cardtable_storage =
1917 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1918 os::vm_page_size(),
1919 HeapRegion::GrainBytes,
1920 G1BlockOffsetSharedArray::N_bytes,
1921 mtGC);
1922
1923 // Reserve space for the card counts table.
1924 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1925 G1RegionToSpaceMapper* card_counts_storage =
1926 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1927 os::vm_page_size(),
1928 HeapRegion::GrainBytes,
1929 G1BlockOffsetSharedArray::N_bytes,
1930 mtGC);
1931
1932 // Reserve space for prev and next bitmap.
1933 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1934
1935 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1936 G1RegionToSpaceMapper* prev_bitmap_storage =
1937 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1938 os::vm_page_size(),
1939 HeapRegion::GrainBytes,
1940 CMBitMap::mark_distance(),
1941 mtGC);
1942
1943 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1944 G1RegionToSpaceMapper* next_bitmap_storage =
1945 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1946 os::vm_page_size(),
1947 HeapRegion::GrainBytes,
1948 CMBitMap::mark_distance(),
1949 mtGC);
1950
1951 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1952 g1_barrier_set()->initialize(cardtable_storage);
1953 // Do later initialization work for concurrent refinement.
1954 _cg1r->init(card_counts_storage);
1955
1956 // 6843694 - ensure that the maximum region index can fit
1957 // in the remembered set structures.
1958 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1959 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1960
1961 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1962 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1963 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1964 "too many cards per region");
1965
1966 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1967
1968 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1969
1970 _g1h = this;
1971
1972 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1973 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1974
1975 // Create the ConcurrentMark data structure and thread.
1976 // (Must do this late, so that "max_regions" is defined.)
1977 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1978 if (_cm == NULL || !_cm->completed_initialization()) {
1979 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1980 return JNI_ENOMEM;
1981 }
1982 _cmThread = _cm->cmThread();
1983
1984 // Initialize the from_card cache structure of HeapRegionRemSet.
1985 HeapRegionRemSet::init_heap(max_regions());
1986
1987 // Now expand into the initial heap size.
1988 if (!expand(init_byte_size)) {
1989 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1990 return JNI_ENOMEM;
1991 }
1992
1993 // Perform any initialization actions delegated to the policy.
1994 g1_policy()->init();
1995
1996 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1997 SATB_Q_FL_lock,
1998 G1SATBProcessCompletedThreshold,
1999 Shared_SATB_Q_lock);
2000
2001 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2002 DirtyCardQ_CBL_mon,
2003 DirtyCardQ_FL_lock,
2004 concurrent_g1_refine()->yellow_zone(),
2005 concurrent_g1_refine()->red_zone(),
2006 Shared_DirtyCardQ_lock);
2007
2008 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2009 DirtyCardQ_CBL_mon,
2010 DirtyCardQ_FL_lock,
2011 -1, // never trigger processing
2012 -1, // no limit on length
2013 Shared_DirtyCardQ_lock,
2014 &JavaThread::dirty_card_queue_set());
2015
2016 // Initialize the card queue set used to hold cards containing
2017 // references into the collection set.
2018 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2019 DirtyCardQ_CBL_mon,
2020 DirtyCardQ_FL_lock,
2021 -1, // never trigger processing
2022 -1, // no limit on length
2023 Shared_DirtyCardQ_lock,
2024 &JavaThread::dirty_card_queue_set());
2025
2026 // In case we're keeping closure specialization stats, initialize those
2027 // counts and that mechanism.
2028 SpecializationStats::clear();
2029
2030 // Here we allocate the dummy HeapRegion that is required by the
2031 // G1AllocRegion class.
2032 HeapRegion* dummy_region = _hrm.get_dummy_region();
2033
2034 // We'll re-use the same region whether the alloc region will
2035 // require BOT updates or not and, if it doesn't, then a non-young
2036 // region will complain that it cannot support allocations without
2037 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2038 dummy_region->set_eden();
2039 // Make sure it's full.
2040 dummy_region->set_top(dummy_region->end());
2041 G1AllocRegion::setup(this, dummy_region);
2042
2043 _allocator->init_mutator_alloc_region();
2044
2045 // Do create of the monitoring and management support so that
2046 // values in the heap have been properly initialized.
2047 _g1mm = new G1MonitoringSupport(this);
2048
2049 G1StringDedup::initialize();
2050
2051 return JNI_OK;
2052 }
2053
2054 void G1CollectedHeap::stop() {
2055 // Stop all concurrent threads. We do this to make sure these threads
2056 // do not continue to execute and access resources (e.g. gclog_or_tty)
2057 // that are destroyed during shutdown.
2058 _cg1r->stop();
2059 _cmThread->stop();
2060 if (G1StringDedup::is_enabled()) {
2061 G1StringDedup::stop();
2062 }
2063 }
2064
2065 void G1CollectedHeap::clear_humongous_is_live_table() {
2066 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2067 _humongous_is_live.clear();
2068 }
2069
2070 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2071 return HeapRegion::max_region_size();
2072 }
2073
2074 void G1CollectedHeap::ref_processing_init() {
2075 // Reference processing in G1 currently works as follows:
2076 //
2077 // * There are two reference processor instances. One is
2078 // used to record and process discovered references
2079 // during concurrent marking; the other is used to
2080 // record and process references during STW pauses
2081 // (both full and incremental).
2082 // * Both ref processors need to 'span' the entire heap as
2083 // the regions in the collection set may be dotted around.
2084 //
2085 // * For the concurrent marking ref processor:
2086 // * Reference discovery is enabled at initial marking.
2087 // * Reference discovery is disabled and the discovered
2088 // references processed etc during remarking.
2089 // * Reference discovery is MT (see below).
2090 // * Reference discovery requires a barrier (see below).
2091 // * Reference processing may or may not be MT
2092 // (depending on the value of ParallelRefProcEnabled
2093 // and ParallelGCThreads).
2094 // * A full GC disables reference discovery by the CM
2095 // ref processor and abandons any entries on it's
2096 // discovered lists.
2097 //
2098 // * For the STW processor:
2099 // * Non MT discovery is enabled at the start of a full GC.
2100 // * Processing and enqueueing during a full GC is non-MT.
2101 // * During a full GC, references are processed after marking.
2102 //
2103 // * Discovery (may or may not be MT) is enabled at the start
2104 // of an incremental evacuation pause.
2105 // * References are processed near the end of a STW evacuation pause.
2106 // * For both types of GC:
2107 // * Discovery is atomic - i.e. not concurrent.
2108 // * Reference discovery will not need a barrier.
2109
2110 SharedHeap::ref_processing_init();
2111 MemRegion mr = reserved_region();
2112
2113 // Concurrent Mark ref processor
2114 _ref_processor_cm =
2115 new ReferenceProcessor(mr, // span
2116 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2117 // mt processing
2118 (int) ParallelGCThreads,
2119 // degree of mt processing
2120 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2121 // mt discovery
2122 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2123 // degree of mt discovery
2124 false,
2125 // Reference discovery is not atomic
2126 &_is_alive_closure_cm);
2127 // is alive closure
2128 // (for efficiency/performance)
2129
2130 // STW ref processor
2131 _ref_processor_stw =
2132 new ReferenceProcessor(mr, // span
2133 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2134 // mt processing
2135 MAX2((int)ParallelGCThreads, 1),
2136 // degree of mt processing
2137 (ParallelGCThreads > 1),
2138 // mt discovery
2139 MAX2((int)ParallelGCThreads, 1),
2140 // degree of mt discovery
2141 true,
2142 // Reference discovery is atomic
2143 &_is_alive_closure_stw);
2144 // is alive closure
2145 // (for efficiency/performance)
2146 }
2147
2148 size_t G1CollectedHeap::capacity() const {
2149 return _hrm.length() * HeapRegion::GrainBytes;
2150 }
2151
2152 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2153 assert(!hr->is_continues_humongous(), "pre-condition");
2154 hr->reset_gc_time_stamp();
2155 if (hr->is_starts_humongous()) {
2156 uint first_index = hr->hrm_index() + 1;
2157 uint last_index = hr->last_hc_index();
2158 for (uint i = first_index; i < last_index; i += 1) {
2159 HeapRegion* chr = region_at(i);
2160 assert(chr->is_continues_humongous(), "sanity");
2161 chr->reset_gc_time_stamp();
2162 }
2163 }
2164 }
2165
2166 #ifndef PRODUCT
2167 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2168 private:
2169 unsigned _gc_time_stamp;
2170 bool _failures;
2171
2172 public:
2173 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2174 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2175
2176 virtual bool doHeapRegion(HeapRegion* hr) {
2177 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2178 if (_gc_time_stamp != region_gc_time_stamp) {
2179 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2180 "expected %d", HR_FORMAT_PARAMS(hr),
2181 region_gc_time_stamp, _gc_time_stamp);
2182 _failures = true;
2183 }
2184 return false;
2185 }
2186
2187 bool failures() { return _failures; }
2188 };
2189
2190 void G1CollectedHeap::check_gc_time_stamps() {
2191 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2192 heap_region_iterate(&cl);
2193 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2194 }
2195 #endif // PRODUCT
2196
2197 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2198 DirtyCardQueue* into_cset_dcq,
2199 bool concurrent,
2200 uint worker_i) {
2201 // Clean cards in the hot card cache
2202 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2203 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2204
2205 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2206 size_t n_completed_buffers = 0;
2207 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2208 n_completed_buffers++;
2209 }
2210 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2211 dcqs.clear_n_completed_buffers();
2212 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2213 }
2214
2215
2216 // Computes the sum of the storage used by the various regions.
2217 size_t G1CollectedHeap::used() const {
2218 return _allocator->used();
2219 }
2220
2221 size_t G1CollectedHeap::used_unlocked() const {
2222 return _allocator->used_unlocked();
2223 }
2224
2225 class SumUsedClosure: public HeapRegionClosure {
2226 size_t _used;
2227 public:
2228 SumUsedClosure() : _used(0) {}
2229 bool doHeapRegion(HeapRegion* r) {
2230 if (!r->is_continues_humongous()) {
2231 _used += r->used();
2232 }
2233 return false;
2234 }
2235 size_t result() { return _used; }
2236 };
2237
2238 size_t G1CollectedHeap::recalculate_used() const {
2239 double recalculate_used_start = os::elapsedTime();
2240
2241 SumUsedClosure blk;
2242 heap_region_iterate(&blk);
2243
2244 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2245 return blk.result();
2246 }
2247
2248 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2249 switch (cause) {
2250 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2251 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2252 case GCCause::_g1_humongous_allocation: return true;
2253 case GCCause::_update_allocation_context_stats_inc: return true;
2254 case GCCause::_wb_conc_mark: return true;
2255 default: return false;
2256 }
2257 }
2258
2259 #ifndef PRODUCT
2260 void G1CollectedHeap::allocate_dummy_regions() {
2261 // Let's fill up most of the region
2262 size_t word_size = HeapRegion::GrainWords - 1024;
2263 // And as a result the region we'll allocate will be humongous.
2264 guarantee(is_humongous(word_size), "sanity");
2265
2266 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2267 // Let's use the existing mechanism for the allocation
2268 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2269 AllocationContext::system());
2270 if (dummy_obj != NULL) {
2271 MemRegion mr(dummy_obj, word_size);
2272 CollectedHeap::fill_with_object(mr);
2273 } else {
2274 // If we can't allocate once, we probably cannot allocate
2275 // again. Let's get out of the loop.
2276 break;
2277 }
2278 }
2279 }
2280 #endif // !PRODUCT
2281
2282 void G1CollectedHeap::increment_old_marking_cycles_started() {
2283 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2284 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2285 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2286 _old_marking_cycles_started, _old_marking_cycles_completed));
2287
2288 _old_marking_cycles_started++;
2289 }
2290
2291 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2292 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2293
2294 // We assume that if concurrent == true, then the caller is a
2295 // concurrent thread that was joined the Suspendible Thread
2296 // Set. If there's ever a cheap way to check this, we should add an
2297 // assert here.
2298
2299 // Given that this method is called at the end of a Full GC or of a
2300 // concurrent cycle, and those can be nested (i.e., a Full GC can
2301 // interrupt a concurrent cycle), the number of full collections
2302 // completed should be either one (in the case where there was no
2303 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2304 // behind the number of full collections started.
2305
2306 // This is the case for the inner caller, i.e. a Full GC.
2307 assert(concurrent ||
2308 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2309 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2310 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2311 "is inconsistent with _old_marking_cycles_completed = %u",
2312 _old_marking_cycles_started, _old_marking_cycles_completed));
2313
2314 // This is the case for the outer caller, i.e. the concurrent cycle.
2315 assert(!concurrent ||
2316 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2317 err_msg("for outer caller (concurrent cycle): "
2318 "_old_marking_cycles_started = %u "
2319 "is inconsistent with _old_marking_cycles_completed = %u",
2320 _old_marking_cycles_started, _old_marking_cycles_completed));
2321
2322 _old_marking_cycles_completed += 1;
2323
2324 // We need to clear the "in_progress" flag in the CM thread before
2325 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2326 // is set) so that if a waiter requests another System.gc() it doesn't
2327 // incorrectly see that a marking cycle is still in progress.
2328 if (concurrent) {
2329 _cmThread->clear_in_progress();
2330 }
2331
2332 // This notify_all() will ensure that a thread that called
2333 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2334 // and it's waiting for a full GC to finish will be woken up. It is
2335 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2336 FullGCCount_lock->notify_all();
2337 }
2338
2339 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2340 _concurrent_cycle_started = true;
2341 _gc_timer_cm->register_gc_start(start_time);
2342
2343 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2344 trace_heap_before_gc(_gc_tracer_cm);
2345 }
2346
2347 void G1CollectedHeap::register_concurrent_cycle_end() {
2348 if (_concurrent_cycle_started) {
2349 if (_cm->has_aborted()) {
2350 _gc_tracer_cm->report_concurrent_mode_failure();
2351 }
2352
2353 _gc_timer_cm->register_gc_end();
2354 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2355
2356 // Clear state variables to prepare for the next concurrent cycle.
2357 _concurrent_cycle_started = false;
2358 _heap_summary_sent = false;
2359 }
2360 }
2361
2362 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2363 if (_concurrent_cycle_started) {
2364 // This function can be called when:
2365 // the cleanup pause is run
2366 // the concurrent cycle is aborted before the cleanup pause.
2367 // the concurrent cycle is aborted after the cleanup pause,
2368 // but before the concurrent cycle end has been registered.
2369 // Make sure that we only send the heap information once.
2370 if (!_heap_summary_sent) {
2371 trace_heap_after_gc(_gc_tracer_cm);
2372 _heap_summary_sent = true;
2373 }
2374 }
2375 }
2376
2377 G1YCType G1CollectedHeap::yc_type() {
2378 bool is_young = g1_policy()->gcs_are_young();
2379 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2380 bool is_during_mark = mark_in_progress();
2381
2382 if (is_initial_mark) {
2383 return InitialMark;
2384 } else if (is_during_mark) {
2385 return DuringMark;
2386 } else if (is_young) {
2387 return Normal;
2388 } else {
2389 return Mixed;
2390 }
2391 }
2392
2393 void G1CollectedHeap::collect(GCCause::Cause cause) {
2394 assert_heap_not_locked();
2395
2396 uint gc_count_before;
2397 uint old_marking_count_before;
2398 uint full_gc_count_before;
2399 bool retry_gc;
2400
2401 do {
2402 retry_gc = false;
2403
2404 {
2405 MutexLocker ml(Heap_lock);
2406
2407 // Read the GC count while holding the Heap_lock
2408 gc_count_before = total_collections();
2409 full_gc_count_before = total_full_collections();
2410 old_marking_count_before = _old_marking_cycles_started;
2411 }
2412
2413 if (should_do_concurrent_full_gc(cause)) {
2414 // Schedule an initial-mark evacuation pause that will start a
2415 // concurrent cycle. We're setting word_size to 0 which means that
2416 // we are not requesting a post-GC allocation.
2417 VM_G1IncCollectionPause op(gc_count_before,
2418 0, /* word_size */
2419 true, /* should_initiate_conc_mark */
2420 g1_policy()->max_pause_time_ms(),
2421 cause);
2422 op.set_allocation_context(AllocationContext::current());
2423
2424 VMThread::execute(&op);
2425 if (!op.pause_succeeded()) {
2426 if (old_marking_count_before == _old_marking_cycles_started) {
2427 retry_gc = op.should_retry_gc();
2428 } else {
2429 // A Full GC happened while we were trying to schedule the
2430 // initial-mark GC. No point in starting a new cycle given
2431 // that the whole heap was collected anyway.
2432 }
2433
2434 if (retry_gc) {
2435 if (GC_locker::is_active_and_needs_gc()) {
2436 GC_locker::stall_until_clear();
2437 }
2438 }
2439 }
2440 } else {
2441 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2442 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2443
2444 // Schedule a standard evacuation pause. We're setting word_size
2445 // to 0 which means that we are not requesting a post-GC allocation.
2446 VM_G1IncCollectionPause op(gc_count_before,
2447 0, /* word_size */
2448 false, /* should_initiate_conc_mark */
2449 g1_policy()->max_pause_time_ms(),
2450 cause);
2451 VMThread::execute(&op);
2452 } else {
2453 // Schedule a Full GC.
2454 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2455 VMThread::execute(&op);
2456 }
2457 }
2458 } while (retry_gc);
2459 }
2460
2461 bool G1CollectedHeap::is_in(const void* p) const {
2462 if (_hrm.reserved().contains(p)) {
2463 // Given that we know that p is in the reserved space,
2464 // heap_region_containing_raw() should successfully
2465 // return the containing region.
2466 HeapRegion* hr = heap_region_containing_raw(p);
2467 return hr->is_in(p);
2468 } else {
2469 return false;
2470 }
2471 }
2472
2473 #ifdef ASSERT
2474 bool G1CollectedHeap::is_in_exact(const void* p) const {
2475 bool contains = reserved_region().contains(p);
2476 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2477 if (contains && available) {
2478 return true;
2479 } else {
2480 return false;
2481 }
2482 }
2483 #endif
2484
2485 // Iteration functions.
2486
2487 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2488
2489 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2490 ExtendedOopClosure* _cl;
2491 public:
2492 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2493 bool doHeapRegion(HeapRegion* r) {
2494 if (!r->is_continues_humongous()) {
2495 r->oop_iterate(_cl);
2496 }
2497 return false;
2498 }
2499 };
2500
2501 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2502 IterateOopClosureRegionClosure blk(cl);
2503 heap_region_iterate(&blk);
2504 }
2505
2506 // Iterates an ObjectClosure over all objects within a HeapRegion.
2507
2508 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2509 ObjectClosure* _cl;
2510 public:
2511 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2512 bool doHeapRegion(HeapRegion* r) {
2513 if (!r->is_continues_humongous()) {
2514 r->object_iterate(_cl);
2515 }
2516 return false;
2517 }
2518 };
2519
2520 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2521 IterateObjectClosureRegionClosure blk(cl);
2522 heap_region_iterate(&blk);
2523 }
2524
2525 // Calls a SpaceClosure on a HeapRegion.
2526
2527 class SpaceClosureRegionClosure: public HeapRegionClosure {
2528 SpaceClosure* _cl;
2529 public:
2530 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2531 bool doHeapRegion(HeapRegion* r) {
2532 _cl->do_space(r);
2533 return false;
2534 }
2535 };
2536
2537 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2538 SpaceClosureRegionClosure blk(cl);
2539 heap_region_iterate(&blk);
2540 }
2541
2542 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2543 _hrm.iterate(cl);
2544 }
2545
2546 void
2547 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2548 uint worker_id,
2549 HeapRegionClaimer *hrclaimer,
2550 bool concurrent) const {
2551 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2552 }
2553
2554 // Clear the cached CSet starting regions and (more importantly)
2555 // the time stamps. Called when we reset the GC time stamp.
2556 void G1CollectedHeap::clear_cset_start_regions() {
2557 assert(_worker_cset_start_region != NULL, "sanity");
2558 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2559
2560 int n_queues = MAX2((int)ParallelGCThreads, 1);
2561 for (int i = 0; i < n_queues; i++) {
2562 _worker_cset_start_region[i] = NULL;
2563 _worker_cset_start_region_time_stamp[i] = 0;
2564 }
2565 }
2566
2567 // Given the id of a worker, obtain or calculate a suitable
2568 // starting region for iterating over the current collection set.
2569 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2570 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2571
2572 HeapRegion* result = NULL;
2573 unsigned gc_time_stamp = get_gc_time_stamp();
2574
2575 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2576 // Cached starting region for current worker was set
2577 // during the current pause - so it's valid.
2578 // Note: the cached starting heap region may be NULL
2579 // (when the collection set is empty).
2580 result = _worker_cset_start_region[worker_i];
2581 assert(result == NULL || result->in_collection_set(), "sanity");
2582 return result;
2583 }
2584
2585 // The cached entry was not valid so let's calculate
2586 // a suitable starting heap region for this worker.
2587
2588 // We want the parallel threads to start their collection
2589 // set iteration at different collection set regions to
2590 // avoid contention.
2591 // If we have:
2592 // n collection set regions
2593 // p threads
2594 // Then thread t will start at region floor ((t * n) / p)
2595
2596 result = g1_policy()->collection_set();
2597 uint cs_size = g1_policy()->cset_region_length();
2598 uint active_workers = workers()->active_workers();
2599 assert(UseDynamicNumberOfGCThreads ||
2600 active_workers == workers()->total_workers(),
2601 "Unless dynamic should use total workers");
2602
2603 uint end_ind = (cs_size * worker_i) / active_workers;
2604 uint start_ind = 0;
2605
2606 if (worker_i > 0 &&
2607 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2608 // Previous workers starting region is valid
2609 // so let's iterate from there
2610 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2611 result = _worker_cset_start_region[worker_i - 1];
2612 }
2613
2614 for (uint i = start_ind; i < end_ind; i++) {
2615 result = result->next_in_collection_set();
2616 }
2617
2618 // Note: the calculated starting heap region may be NULL
2619 // (when the collection set is empty).
2620 assert(result == NULL || result->in_collection_set(), "sanity");
2621 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2622 "should be updated only once per pause");
2623 _worker_cset_start_region[worker_i] = result;
2624 OrderAccess::storestore();
2625 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2626 return result;
2627 }
2628
2629 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2630 HeapRegion* r = g1_policy()->collection_set();
2631 while (r != NULL) {
2632 HeapRegion* next = r->next_in_collection_set();
2633 if (cl->doHeapRegion(r)) {
2634 cl->incomplete();
2635 return;
2636 }
2637 r = next;
2638 }
2639 }
2640
2641 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2642 HeapRegionClosure *cl) {
2643 if (r == NULL) {
2644 // The CSet is empty so there's nothing to do.
2645 return;
2646 }
2647
2648 assert(r->in_collection_set(),
2649 "Start region must be a member of the collection set.");
2650 HeapRegion* cur = r;
2651 while (cur != NULL) {
2652 HeapRegion* next = cur->next_in_collection_set();
2653 if (cl->doHeapRegion(cur) && false) {
2654 cl->incomplete();
2655 return;
2656 }
2657 cur = next;
2658 }
2659 cur = g1_policy()->collection_set();
2660 while (cur != r) {
2661 HeapRegion* next = cur->next_in_collection_set();
2662 if (cl->doHeapRegion(cur) && false) {
2663 cl->incomplete();
2664 return;
2665 }
2666 cur = next;
2667 }
2668 }
2669
2670 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2671 HeapRegion* result = _hrm.next_region_in_heap(from);
2672 while (result != NULL && result->is_humongous()) {
2673 result = _hrm.next_region_in_heap(result);
2674 }
2675 return result;
2676 }
2677
2678 Space* G1CollectedHeap::space_containing(const void* addr) const {
2679 return heap_region_containing(addr);
2680 }
2681
2682 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2683 Space* sp = space_containing(addr);
2684 return sp->block_start(addr);
2685 }
2686
2687 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2688 Space* sp = space_containing(addr);
2689 return sp->block_size(addr);
2690 }
2691
2692 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2693 Space* sp = space_containing(addr);
2694 return sp->block_is_obj(addr);
2695 }
2696
2697 bool G1CollectedHeap::supports_tlab_allocation() const {
2698 return true;
2699 }
2700
2701 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2702 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2703 }
2704
2705 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2706 return young_list()->eden_used_bytes();
2707 }
2708
2709 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2710 // must be smaller than the humongous object limit.
2711 size_t G1CollectedHeap::max_tlab_size() const {
2712 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2713 }
2714
2715 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2716 // Return the remaining space in the cur alloc region, but not less than
2717 // the min TLAB size.
2718
2719 // Also, this value can be at most the humongous object threshold,
2720 // since we can't allow tlabs to grow big enough to accommodate
2721 // humongous objects.
2722
2723 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2724 size_t max_tlab = max_tlab_size() * wordSize;
2725 if (hr == NULL) {
2726 return max_tlab;
2727 } else {
2728 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2729 }
2730 }
2731
2732 size_t G1CollectedHeap::max_capacity() const {
2733 return _hrm.reserved().byte_size();
2734 }
2735
2736 jlong G1CollectedHeap::millis_since_last_gc() {
2737 // assert(false, "NYI");
2738 return 0;
2739 }
2740
2741 void G1CollectedHeap::prepare_for_verify() {
2742 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2743 ensure_parsability(false);
2744 }
2745 g1_rem_set()->prepare_for_verify();
2746 }
2747
2748 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2749 VerifyOption vo) {
2750 switch (vo) {
2751 case VerifyOption_G1UsePrevMarking:
2752 return hr->obj_allocated_since_prev_marking(obj);
2753 case VerifyOption_G1UseNextMarking:
2754 return hr->obj_allocated_since_next_marking(obj);
2755 case VerifyOption_G1UseMarkWord:
2756 return false;
2757 default:
2758 ShouldNotReachHere();
2759 }
2760 return false; // keep some compilers happy
2761 }
2762
2763 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2764 switch (vo) {
2765 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2766 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2767 case VerifyOption_G1UseMarkWord: return NULL;
2768 default: ShouldNotReachHere();
2769 }
2770 return NULL; // keep some compilers happy
2771 }
2772
2773 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2774 switch (vo) {
2775 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2776 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2777 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2778 default: ShouldNotReachHere();
2779 }
2780 return false; // keep some compilers happy
2781 }
2782
2783 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2784 switch (vo) {
2785 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2786 case VerifyOption_G1UseNextMarking: return "NTAMS";
2787 case VerifyOption_G1UseMarkWord: return "NONE";
2788 default: ShouldNotReachHere();
2789 }
2790 return NULL; // keep some compilers happy
2791 }
2792
2793 class VerifyRootsClosure: public OopClosure {
2794 private:
2795 G1CollectedHeap* _g1h;
2796 VerifyOption _vo;
2797 bool _failures;
2798 public:
2799 // _vo == UsePrevMarking -> use "prev" marking information,
2800 // _vo == UseNextMarking -> use "next" marking information,
2801 // _vo == UseMarkWord -> use mark word from object header.
2802 VerifyRootsClosure(VerifyOption vo) :
2803 _g1h(G1CollectedHeap::heap()),
2804 _vo(vo),
2805 _failures(false) { }
2806
2807 bool failures() { return _failures; }
2808
2809 template <class T> void do_oop_nv(T* p) {
2810 T heap_oop = oopDesc::load_heap_oop(p);
2811 if (!oopDesc::is_null(heap_oop)) {
2812 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2813 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2814 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2815 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2816 if (_vo == VerifyOption_G1UseMarkWord) {
2817 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2818 }
2819 obj->print_on(gclog_or_tty);
2820 _failures = true;
2821 }
2822 }
2823 }
2824
2825 void do_oop(oop* p) { do_oop_nv(p); }
2826 void do_oop(narrowOop* p) { do_oop_nv(p); }
2827 };
2828
2829 class G1VerifyCodeRootOopClosure: public OopClosure {
2830 G1CollectedHeap* _g1h;
2831 OopClosure* _root_cl;
2832 nmethod* _nm;
2833 VerifyOption _vo;
2834 bool _failures;
2835
2836 template <class T> void do_oop_work(T* p) {
2837 // First verify that this root is live
2838 _root_cl->do_oop(p);
2839
2840 if (!G1VerifyHeapRegionCodeRoots) {
2841 // We're not verifying the code roots attached to heap region.
2842 return;
2843 }
2844
2845 // Don't check the code roots during marking verification in a full GC
2846 if (_vo == VerifyOption_G1UseMarkWord) {
2847 return;
2848 }
2849
2850 // Now verify that the current nmethod (which contains p) is
2851 // in the code root list of the heap region containing the
2852 // object referenced by p.
2853
2854 T heap_oop = oopDesc::load_heap_oop(p);
2855 if (!oopDesc::is_null(heap_oop)) {
2856 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2857
2858 // Now fetch the region containing the object
2859 HeapRegion* hr = _g1h->heap_region_containing(obj);
2860 HeapRegionRemSet* hrrs = hr->rem_set();
2861 // Verify that the strong code root list for this region
2862 // contains the nmethod
2863 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2864 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2865 "from nmethod "PTR_FORMAT" not in strong "
2866 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2867 p, _nm, hr->bottom(), hr->end());
2868 _failures = true;
2869 }
2870 }
2871 }
2872
2873 public:
2874 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2875 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2876
2877 void do_oop(oop* p) { do_oop_work(p); }
2878 void do_oop(narrowOop* p) { do_oop_work(p); }
2879
2880 void set_nmethod(nmethod* nm) { _nm = nm; }
2881 bool failures() { return _failures; }
2882 };
2883
2884 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2885 G1VerifyCodeRootOopClosure* _oop_cl;
2886
2887 public:
2888 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2889 _oop_cl(oop_cl) {}
2890
2891 void do_code_blob(CodeBlob* cb) {
2892 nmethod* nm = cb->as_nmethod_or_null();
2893 if (nm != NULL) {
2894 _oop_cl->set_nmethod(nm);
2895 nm->oops_do(_oop_cl);
2896 }
2897 }
2898 };
2899
2900 class YoungRefCounterClosure : public OopClosure {
2901 G1CollectedHeap* _g1h;
2902 int _count;
2903 public:
2904 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2905 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2906 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2907
2908 int count() { return _count; }
2909 void reset_count() { _count = 0; };
2910 };
2911
2912 class VerifyKlassClosure: public KlassClosure {
2913 YoungRefCounterClosure _young_ref_counter_closure;
2914 OopClosure *_oop_closure;
2915 public:
2916 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2917 void do_klass(Klass* k) {
2918 k->oops_do(_oop_closure);
2919
2920 _young_ref_counter_closure.reset_count();
2921 k->oops_do(&_young_ref_counter_closure);
2922 if (_young_ref_counter_closure.count() > 0) {
2923 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2924 }
2925 }
2926 };
2927
2928 class VerifyLivenessOopClosure: public OopClosure {
2929 G1CollectedHeap* _g1h;
2930 VerifyOption _vo;
2931 public:
2932 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2933 _g1h(g1h), _vo(vo)
2934 { }
2935 void do_oop(narrowOop *p) { do_oop_work(p); }
2936 void do_oop( oop *p) { do_oop_work(p); }
2937
2938 template <class T> void do_oop_work(T *p) {
2939 oop obj = oopDesc::load_decode_heap_oop(p);
2940 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2941 "Dead object referenced by a not dead object");
2942 }
2943 };
2944
2945 class VerifyObjsInRegionClosure: public ObjectClosure {
2946 private:
2947 G1CollectedHeap* _g1h;
2948 size_t _live_bytes;
2949 HeapRegion *_hr;
2950 VerifyOption _vo;
2951 public:
2952 // _vo == UsePrevMarking -> use "prev" marking information,
2953 // _vo == UseNextMarking -> use "next" marking information,
2954 // _vo == UseMarkWord -> use mark word from object header.
2955 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2956 : _live_bytes(0), _hr(hr), _vo(vo) {
2957 _g1h = G1CollectedHeap::heap();
2958 }
2959 void do_object(oop o) {
2960 VerifyLivenessOopClosure isLive(_g1h, _vo);
2961 assert(o != NULL, "Huh?");
2962 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2963 // If the object is alive according to the mark word,
2964 // then verify that the marking information agrees.
2965 // Note we can't verify the contra-positive of the
2966 // above: if the object is dead (according to the mark
2967 // word), it may not be marked, or may have been marked
2968 // but has since became dead, or may have been allocated
2969 // since the last marking.
2970 if (_vo == VerifyOption_G1UseMarkWord) {
2971 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2972 }
2973
2974 o->oop_iterate_no_header(&isLive);
2975 if (!_hr->obj_allocated_since_prev_marking(o)) {
2976 size_t obj_size = o->size(); // Make sure we don't overflow
2977 _live_bytes += (obj_size * HeapWordSize);
2978 }
2979 }
2980 }
2981 size_t live_bytes() { return _live_bytes; }
2982 };
2983
2984 class PrintObjsInRegionClosure : public ObjectClosure {
2985 HeapRegion *_hr;
2986 G1CollectedHeap *_g1;
2987 public:
2988 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2989 _g1 = G1CollectedHeap::heap();
2990 };
2991
2992 void do_object(oop o) {
2993 if (o != NULL) {
2994 HeapWord *start = (HeapWord *) o;
2995 size_t word_sz = o->size();
2996 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2997 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2998 (void*) o, word_sz,
2999 _g1->isMarkedPrev(o),
3000 _g1->isMarkedNext(o),
3001 _hr->obj_allocated_since_prev_marking(o));
3002 HeapWord *end = start + word_sz;
3003 HeapWord *cur;
3004 int *val;
3005 for (cur = start; cur < end; cur++) {
3006 val = (int *) cur;
3007 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3008 }
3009 }
3010 }
3011 };
3012
3013 class VerifyRegionClosure: public HeapRegionClosure {
3014 private:
3015 bool _par;
3016 VerifyOption _vo;
3017 bool _failures;
3018 public:
3019 // _vo == UsePrevMarking -> use "prev" marking information,
3020 // _vo == UseNextMarking -> use "next" marking information,
3021 // _vo == UseMarkWord -> use mark word from object header.
3022 VerifyRegionClosure(bool par, VerifyOption vo)
3023 : _par(par),
3024 _vo(vo),
3025 _failures(false) {}
3026
3027 bool failures() {
3028 return _failures;
3029 }
3030
3031 bool doHeapRegion(HeapRegion* r) {
3032 if (!r->is_continues_humongous()) {
3033 bool failures = false;
3034 r->verify(_vo, &failures);
3035 if (failures) {
3036 _failures = true;
3037 } else {
3038 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3039 r->object_iterate(¬_dead_yet_cl);
3040 if (_vo != VerifyOption_G1UseNextMarking) {
3041 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3042 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3043 "max_live_bytes "SIZE_FORMAT" "
3044 "< calculated "SIZE_FORMAT,
3045 r->bottom(), r->end(),
3046 r->max_live_bytes(),
3047 not_dead_yet_cl.live_bytes());
3048 _failures = true;
3049 }
3050 } else {
3051 // When vo == UseNextMarking we cannot currently do a sanity
3052 // check on the live bytes as the calculation has not been
3053 // finalized yet.
3054 }
3055 }
3056 }
3057 return false; // stop the region iteration if we hit a failure
3058 }
3059 };
3060
3061 // This is the task used for parallel verification of the heap regions
3062
3063 class G1ParVerifyTask: public AbstractGangTask {
3064 private:
3065 G1CollectedHeap* _g1h;
3066 VerifyOption _vo;
3067 bool _failures;
3068 HeapRegionClaimer _hrclaimer;
3069
3070 public:
3071 // _vo == UsePrevMarking -> use "prev" marking information,
3072 // _vo == UseNextMarking -> use "next" marking information,
3073 // _vo == UseMarkWord -> use mark word from object header.
3074 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3075 AbstractGangTask("Parallel verify task"),
3076 _g1h(g1h),
3077 _vo(vo),
3078 _failures(false),
3079 _hrclaimer(g1h->workers()->active_workers()) {}
3080
3081 bool failures() {
3082 return _failures;
3083 }
3084
3085 void work(uint worker_id) {
3086 HandleMark hm;
3087 VerifyRegionClosure blk(true, _vo);
3088 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3089 if (blk.failures()) {
3090 _failures = true;
3091 }
3092 }
3093 };
3094
3095 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3096 if (SafepointSynchronize::is_at_safepoint()) {
3097 assert(Thread::current()->is_VM_thread(),
3098 "Expected to be executed serially by the VM thread at this point");
3099
3100 if (!silent) { gclog_or_tty->print("Roots "); }
3101 VerifyRootsClosure rootsCl(vo);
3102 VerifyKlassClosure klassCl(this, &rootsCl);
3103 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3104
3105 // We apply the relevant closures to all the oops in the
3106 // system dictionary, class loader data graph, the string table
3107 // and the nmethods in the code cache.
3108 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3109 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3110
3111 G1RootProcessor root_processor(this, false /* trace_metadata */);
3112 root_processor.process_all_roots(&rootsCl,
3113 &cldCl,
3114 &blobsCl);
3115
3116 bool failures = rootsCl.failures() || codeRootsCl.failures();
3117
3118 if (vo != VerifyOption_G1UseMarkWord) {
3119 // If we're verifying during a full GC then the region sets
3120 // will have been torn down at the start of the GC. Therefore
3121 // verifying the region sets will fail. So we only verify
3122 // the region sets when not in a full GC.
3123 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3124 verify_region_sets();
3125 }
3126
3127 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3128 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3129
3130 G1ParVerifyTask task(this, vo);
3131 assert(UseDynamicNumberOfGCThreads ||
3132 workers()->active_workers() == workers()->total_workers(),
3133 "If not dynamic should be using all the workers");
3134 int n_workers = workers()->active_workers();
3135 set_par_threads(n_workers);
3136 workers()->run_task(&task);
3137 set_par_threads(0);
3138 if (task.failures()) {
3139 failures = true;
3140 }
3141
3142 } else {
3143 VerifyRegionClosure blk(false, vo);
3144 heap_region_iterate(&blk);
3145 if (blk.failures()) {
3146 failures = true;
3147 }
3148 }
3149
3150 if (G1StringDedup::is_enabled()) {
3151 if (!silent) gclog_or_tty->print("StrDedup ");
3152 G1StringDedup::verify();
3153 }
3154
3155 if (failures) {
3156 gclog_or_tty->print_cr("Heap:");
3157 // It helps to have the per-region information in the output to
3158 // help us track down what went wrong. This is why we call
3159 // print_extended_on() instead of print_on().
3160 print_extended_on(gclog_or_tty);
3161 gclog_or_tty->cr();
3162 #ifndef PRODUCT
3163 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3164 concurrent_mark()->print_reachable("at-verification-failure",
3165 vo, false /* all */);
3166 }
3167 #endif
3168 gclog_or_tty->flush();
3169 }
3170 guarantee(!failures, "there should not have been any failures");
3171 } else {
3172 if (!silent) {
3173 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3174 if (G1StringDedup::is_enabled()) {
3175 gclog_or_tty->print(", StrDedup");
3176 }
3177 gclog_or_tty->print(") ");
3178 }
3179 }
3180 }
3181
3182 void G1CollectedHeap::verify(bool silent) {
3183 verify(silent, VerifyOption_G1UsePrevMarking);
3184 }
3185
3186 double G1CollectedHeap::verify(bool guard, const char* msg) {
3187 double verify_time_ms = 0.0;
3188
3189 if (guard && total_collections() >= VerifyGCStartAt) {
3190 double verify_start = os::elapsedTime();
3191 HandleMark hm; // Discard invalid handles created during verification
3192 prepare_for_verify();
3193 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3194 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3195 }
3196
3197 return verify_time_ms;
3198 }
3199
3200 void G1CollectedHeap::verify_before_gc() {
3201 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3202 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3203 }
3204
3205 void G1CollectedHeap::verify_after_gc() {
3206 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3207 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3208 }
3209
3210 class PrintRegionClosure: public HeapRegionClosure {
3211 outputStream* _st;
3212 public:
3213 PrintRegionClosure(outputStream* st) : _st(st) {}
3214 bool doHeapRegion(HeapRegion* r) {
3215 r->print_on(_st);
3216 return false;
3217 }
3218 };
3219
3220 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3221 const HeapRegion* hr,
3222 const VerifyOption vo) const {
3223 switch (vo) {
3224 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3225 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3226 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3227 default: ShouldNotReachHere();
3228 }
3229 return false; // keep some compilers happy
3230 }
3231
3232 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3233 const VerifyOption vo) const {
3234 switch (vo) {
3235 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3236 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3237 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3238 default: ShouldNotReachHere();
3239 }
3240 return false; // keep some compilers happy
3241 }
3242
3243 void G1CollectedHeap::print_on(outputStream* st) const {
3244 st->print(" %-20s", "garbage-first heap");
3245 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3246 capacity()/K, used_unlocked()/K);
3247 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3248 _hrm.reserved().start(),
3249 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3250 _hrm.reserved().end());
3251 st->cr();
3252 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3253 uint young_regions = _young_list->length();
3254 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3255 (size_t) young_regions * HeapRegion::GrainBytes / K);
3256 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3257 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3258 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3259 st->cr();
3260 MetaspaceAux::print_on(st);
3261 }
3262
3263 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3264 print_on(st);
3265
3266 // Print the per-region information.
3267 st->cr();
3268 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3269 "HS=humongous(starts), HC=humongous(continues), "
3270 "CS=collection set, F=free, TS=gc time stamp, "
3271 "PTAMS=previous top-at-mark-start, "
3272 "NTAMS=next top-at-mark-start)");
3273 PrintRegionClosure blk(st);
3274 heap_region_iterate(&blk);
3275 }
3276
3277 void G1CollectedHeap::print_on_error(outputStream* st) const {
3278 this->CollectedHeap::print_on_error(st);
3279
3280 if (_cm != NULL) {
3281 st->cr();
3282 _cm->print_on_error(st);
3283 }
3284 }
3285
3286 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3287 workers()->print_worker_threads_on(st);
3288 _cmThread->print_on(st);
3289 st->cr();
3290 _cm->print_worker_threads_on(st);
3291 _cg1r->print_worker_threads_on(st);
3292 if (G1StringDedup::is_enabled()) {
3293 G1StringDedup::print_worker_threads_on(st);
3294 }
3295 }
3296
3297 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3298 workers()->threads_do(tc);
3299 tc->do_thread(_cmThread);
3300 _cg1r->threads_do(tc);
3301 if (G1StringDedup::is_enabled()) {
3302 G1StringDedup::threads_do(tc);
3303 }
3304 }
3305
3306 void G1CollectedHeap::print_tracing_info() const {
3307 // We'll overload this to mean "trace GC pause statistics."
3308 if (TraceYoungGenTime || TraceOldGenTime) {
3309 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3310 // to that.
3311 g1_policy()->print_tracing_info();
3312 }
3313 if (G1SummarizeRSetStats) {
3314 g1_rem_set()->print_summary_info();
3315 }
3316 if (G1SummarizeConcMark) {
3317 concurrent_mark()->print_summary_info();
3318 }
3319 g1_policy()->print_yg_surv_rate_info();
3320 SpecializationStats::print();
3321 }
3322
3323 #ifndef PRODUCT
3324 // Helpful for debugging RSet issues.
3325
3326 class PrintRSetsClosure : public HeapRegionClosure {
3327 private:
3328 const char* _msg;
3329 size_t _occupied_sum;
3330
3331 public:
3332 bool doHeapRegion(HeapRegion* r) {
3333 HeapRegionRemSet* hrrs = r->rem_set();
3334 size_t occupied = hrrs->occupied();
3335 _occupied_sum += occupied;
3336
3337 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3338 HR_FORMAT_PARAMS(r));
3339 if (occupied == 0) {
3340 gclog_or_tty->print_cr(" RSet is empty");
3341 } else {
3342 hrrs->print();
3343 }
3344 gclog_or_tty->print_cr("----------");
3345 return false;
3346 }
3347
3348 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3349 gclog_or_tty->cr();
3350 gclog_or_tty->print_cr("========================================");
3351 gclog_or_tty->print_cr("%s", msg);
3352 gclog_or_tty->cr();
3353 }
3354
3355 ~PrintRSetsClosure() {
3356 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3357 gclog_or_tty->print_cr("========================================");
3358 gclog_or_tty->cr();
3359 }
3360 };
3361
3362 void G1CollectedHeap::print_cset_rsets() {
3363 PrintRSetsClosure cl("Printing CSet RSets");
3364 collection_set_iterate(&cl);
3365 }
3366
3367 void G1CollectedHeap::print_all_rsets() {
3368 PrintRSetsClosure cl("Printing All RSets");;
3369 heap_region_iterate(&cl);
3370 }
3371 #endif // PRODUCT
3372
3373 G1CollectedHeap* G1CollectedHeap::heap() {
3374 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3375 "not a garbage-first heap");
3376 return _g1h;
3377 }
3378
3379 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3380 // always_do_update_barrier = false;
3381 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3382 // Fill TLAB's and such
3383 accumulate_statistics_all_tlabs();
3384 ensure_parsability(true);
3385
3386 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3387 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3388 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3389 }
3390 }
3391
3392 void G1CollectedHeap::gc_epilogue(bool full) {
3393
3394 if (G1SummarizeRSetStats &&
3395 (G1SummarizeRSetStatsPeriod > 0) &&
3396 // we are at the end of the GC. Total collections has already been increased.
3397 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3398 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3399 }
3400
3401 // FIXME: what is this about?
3402 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3403 // is set.
3404 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3405 "derived pointer present"));
3406 // always_do_update_barrier = true;
3407
3408 resize_all_tlabs();
3409 allocation_context_stats().update(full);
3410
3411 // We have just completed a GC. Update the soft reference
3412 // policy with the new heap occupancy
3413 Universe::update_heap_info_at_gc();
3414 }
3415
3416 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3417 uint gc_count_before,
3418 bool* succeeded,
3419 GCCause::Cause gc_cause) {
3420 assert_heap_not_locked_and_not_at_safepoint();
3421 g1_policy()->record_stop_world_start();
3422 VM_G1IncCollectionPause op(gc_count_before,
3423 word_size,
3424 false, /* should_initiate_conc_mark */
3425 g1_policy()->max_pause_time_ms(),
3426 gc_cause);
3427
3428 op.set_allocation_context(AllocationContext::current());
3429 VMThread::execute(&op);
3430
3431 HeapWord* result = op.result();
3432 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3433 assert(result == NULL || ret_succeeded,
3434 "the result should be NULL if the VM did not succeed");
3435 *succeeded = ret_succeeded;
3436
3437 assert_heap_not_locked();
3438 return result;
3439 }
3440
3441 void
3442 G1CollectedHeap::doConcurrentMark() {
3443 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3444 if (!_cmThread->in_progress()) {
3445 _cmThread->set_started();
3446 CGC_lock->notify();
3447 }
3448 }
3449
3450 size_t G1CollectedHeap::pending_card_num() {
3451 size_t extra_cards = 0;
3452 JavaThread *curr = Threads::first();
3453 while (curr != NULL) {
3454 DirtyCardQueue& dcq = curr->dirty_card_queue();
3455 extra_cards += dcq.size();
3456 curr = curr->next();
3457 }
3458 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3459 size_t buffer_size = dcqs.buffer_size();
3460 size_t buffer_num = dcqs.completed_buffers_num();
3461
3462 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3463 // in bytes - not the number of 'entries'. We need to convert
3464 // into a number of cards.
3465 return (buffer_size * buffer_num + extra_cards) / oopSize;
3466 }
3467
3468 size_t G1CollectedHeap::cards_scanned() {
3469 return g1_rem_set()->cardsScanned();
3470 }
3471
3472 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3473 HeapRegion* region = region_at(index);
3474 assert(region->is_starts_humongous(), "Must start a humongous object");
3475 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3476 }
3477
3478 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3479 private:
3480 size_t _total_humongous;
3481 size_t _candidate_humongous;
3482
3483 DirtyCardQueue _dcq;
3484
3485 bool humongous_region_is_candidate(uint index) {
3486 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3487 assert(region->is_starts_humongous(), "Must start a humongous object");
3488 HeapRegionRemSet* const rset = region->rem_set();
3489 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3490 return !oop(region->bottom())->is_objArray() &&
3491 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3492 (!allow_stale_refs && rset->is_empty()));
3493 }
3494
3495 public:
3496 RegisterHumongousWithInCSetFastTestClosure()
3497 : _total_humongous(0),
3498 _candidate_humongous(0),
3499 _dcq(&JavaThread::dirty_card_queue_set()) {
3500 }
3501
3502 virtual bool doHeapRegion(HeapRegion* r) {
3503 if (!r->is_starts_humongous()) {
3504 return false;
3505 }
3506 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3507
3508 uint region_idx = r->hrm_index();
3509 bool is_candidate = humongous_region_is_candidate(region_idx);
3510 // Is_candidate already filters out humongous object with large remembered sets.
3511 // If we have a humongous object with a few remembered sets, we simply flush these
3512 // remembered set entries into the DCQS. That will result in automatic
3513 // re-evaluation of their remembered set entries during the following evacuation
3514 // phase.
3515 if (is_candidate) {
3516 if (!r->rem_set()->is_empty()) {
3517 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3518 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3519 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3520 HeapRegionRemSetIterator hrrs(r->rem_set());
3521 size_t card_index;
3522 while (hrrs.has_next(card_index)) {
3523 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3524 // The remembered set might contain references to already freed
3525 // regions. Filter out such entries to avoid failing card table
3526 // verification.
3527 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3528 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3529 *card_ptr = CardTableModRefBS::dirty_card_val();
3530 _dcq.enqueue(card_ptr);
3531 }
3532 }
3533 }
3534 r->rem_set()->clear_locked();
3535 }
3536 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3537 g1h->register_humongous_region_with_cset(region_idx);
3538 _candidate_humongous++;
3539 }
3540 _total_humongous++;
3541
3542 return false;
3543 }
3544
3545 size_t total_humongous() const { return _total_humongous; }
3546 size_t candidate_humongous() const { return _candidate_humongous; }
3547
3548 void flush_rem_set_entries() { _dcq.flush(); }
3549 };
3550
3551 void G1CollectedHeap::register_humongous_regions_with_cset() {
3552 if (!G1EagerReclaimHumongousObjects) {
3553 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3554 return;
3555 }
3556 double time = os::elapsed_counter();
3557
3558 RegisterHumongousWithInCSetFastTestClosure cl;
3559 heap_region_iterate(&cl);
3560
3561 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3562 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3563 cl.total_humongous(),
3564 cl.candidate_humongous());
3565 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3566
3567 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3568 clear_humongous_is_live_table();
3569 }
3570
3571 // Finally flush all remembered set entries to re-check into the global DCQS.
3572 cl.flush_rem_set_entries();
3573 }
3574
3575 void
3576 G1CollectedHeap::setup_surviving_young_words() {
3577 assert(_surviving_young_words == NULL, "pre-condition");
3578 uint array_length = g1_policy()->young_cset_region_length();
3579 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3580 if (_surviving_young_words == NULL) {
3581 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3582 "Not enough space for young surv words summary.");
3583 }
3584 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3585 #ifdef ASSERT
3586 for (uint i = 0; i < array_length; ++i) {
3587 assert( _surviving_young_words[i] == 0, "memset above" );
3588 }
3589 #endif // !ASSERT
3590 }
3591
3592 void
3593 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3594 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3595 uint array_length = g1_policy()->young_cset_region_length();
3596 for (uint i = 0; i < array_length; ++i) {
3597 _surviving_young_words[i] += surv_young_words[i];
3598 }
3599 }
3600
3601 void
3602 G1CollectedHeap::cleanup_surviving_young_words() {
3603 guarantee( _surviving_young_words != NULL, "pre-condition" );
3604 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3605 _surviving_young_words = NULL;
3606 }
3607
3608 #ifdef ASSERT
3609 class VerifyCSetClosure: public HeapRegionClosure {
3610 public:
3611 bool doHeapRegion(HeapRegion* hr) {
3612 // Here we check that the CSet region's RSet is ready for parallel
3613 // iteration. The fields that we'll verify are only manipulated
3614 // when the region is part of a CSet and is collected. Afterwards,
3615 // we reset these fields when we clear the region's RSet (when the
3616 // region is freed) so they are ready when the region is
3617 // re-allocated. The only exception to this is if there's an
3618 // evacuation failure and instead of freeing the region we leave
3619 // it in the heap. In that case, we reset these fields during
3620 // evacuation failure handling.
3621 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3622
3623 // Here's a good place to add any other checks we'd like to
3624 // perform on CSet regions.
3625 return false;
3626 }
3627 };
3628 #endif // ASSERT
3629
3630 #if TASKQUEUE_STATS
3631 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3632 st->print_raw_cr("GC Task Stats");
3633 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3634 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3635 }
3636
3637 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3638 print_taskqueue_stats_hdr(st);
3639
3640 TaskQueueStats totals;
3641 const int n = workers()->total_workers();
3642 for (int i = 0; i < n; ++i) {
3643 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3644 totals += task_queue(i)->stats;
3645 }
3646 st->print_raw("tot "); totals.print(st); st->cr();
3647
3648 DEBUG_ONLY(totals.verify());
3649 }
3650
3651 void G1CollectedHeap::reset_taskqueue_stats() {
3652 const int n = workers()->total_workers();
3653 for (int i = 0; i < n; ++i) {
3654 task_queue(i)->stats.reset();
3655 }
3656 }
3657 #endif // TASKQUEUE_STATS
3658
3659 void G1CollectedHeap::log_gc_header() {
3660 if (!G1Log::fine()) {
3661 return;
3662 }
3663
3664 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3665
3666 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3667 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3668 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3669
3670 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3671 }
3672
3673 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3674 if (!G1Log::fine()) {
3675 return;
3676 }
3677
3678 if (G1Log::finer()) {
3679 if (evacuation_failed()) {
3680 gclog_or_tty->print(" (to-space exhausted)");
3681 }
3682 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3683 g1_policy()->phase_times()->note_gc_end();
3684 g1_policy()->phase_times()->print(pause_time_sec);
3685 g1_policy()->print_detailed_heap_transition();
3686 } else {
3687 if (evacuation_failed()) {
3688 gclog_or_tty->print("--");
3689 }
3690 g1_policy()->print_heap_transition();
3691 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3692 }
3693 gclog_or_tty->flush();
3694 }
3695
3696 bool
3697 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3698 assert_at_safepoint(true /* should_be_vm_thread */);
3699 guarantee(!is_gc_active(), "collection is not reentrant");
3700
3701 if (GC_locker::check_active_before_gc()) {
3702 return false;
3703 }
3704
3705 _gc_timer_stw->register_gc_start();
3706
3707 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3708
3709 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3710 ResourceMark rm;
3711
3712 print_heap_before_gc();
3713 trace_heap_before_gc(_gc_tracer_stw);
3714
3715 verify_region_sets_optional();
3716 verify_dirty_young_regions();
3717
3718 // This call will decide whether this pause is an initial-mark
3719 // pause. If it is, during_initial_mark_pause() will return true
3720 // for the duration of this pause.
3721 g1_policy()->decide_on_conc_mark_initiation();
3722
3723 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3724 assert(!g1_policy()->during_initial_mark_pause() ||
3725 g1_policy()->gcs_are_young(), "sanity");
3726
3727 // We also do not allow mixed GCs during marking.
3728 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3729
3730 // Record whether this pause is an initial mark. When the current
3731 // thread has completed its logging output and it's safe to signal
3732 // the CM thread, the flag's value in the policy has been reset.
3733 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3734
3735 // Inner scope for scope based logging, timers, and stats collection
3736 {
3737 EvacuationInfo evacuation_info;
3738
3739 if (g1_policy()->during_initial_mark_pause()) {
3740 // We are about to start a marking cycle, so we increment the
3741 // full collection counter.
3742 increment_old_marking_cycles_started();
3743 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3744 }
3745
3746 _gc_tracer_stw->report_yc_type(yc_type());
3747
3748 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3749
3750 uint active_workers = workers()->active_workers();
3751 double pause_start_sec = os::elapsedTime();
3752 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3753 log_gc_header();
3754
3755 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3756 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3757
3758 // If the secondary_free_list is not empty, append it to the
3759 // free_list. No need to wait for the cleanup operation to finish;
3760 // the region allocation code will check the secondary_free_list
3761 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3762 // set, skip this step so that the region allocation code has to
3763 // get entries from the secondary_free_list.
3764 if (!G1StressConcRegionFreeing) {
3765 append_secondary_free_list_if_not_empty_with_lock();
3766 }
3767
3768 assert(check_young_list_well_formed(), "young list should be well formed");
3769
3770 // Don't dynamically change the number of GC threads this early. A value of
3771 // 0 is used to indicate serial work. When parallel work is done,
3772 // it will be set.
3773
3774 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3775 IsGCActiveMark x;
3776
3777 gc_prologue(false);
3778 increment_total_collections(false /* full gc */);
3779 increment_gc_time_stamp();
3780
3781 verify_before_gc();
3782
3783 check_bitmaps("GC Start");
3784
3785 COMPILER2_PRESENT(DerivedPointerTable::clear());
3786
3787 // Please see comment in g1CollectedHeap.hpp and
3788 // G1CollectedHeap::ref_processing_init() to see how
3789 // reference processing currently works in G1.
3790
3791 // Enable discovery in the STW reference processor
3792 ref_processor_stw()->enable_discovery();
3793
3794 {
3795 // We want to temporarily turn off discovery by the
3796 // CM ref processor, if necessary, and turn it back on
3797 // on again later if we do. Using a scoped
3798 // NoRefDiscovery object will do this.
3799 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3800
3801 // Forget the current alloc region (we might even choose it to be part
3802 // of the collection set!).
3803 _allocator->release_mutator_alloc_region();
3804
3805 // We should call this after we retire the mutator alloc
3806 // region(s) so that all the ALLOC / RETIRE events are generated
3807 // before the start GC event.
3808 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3809
3810 // This timing is only used by the ergonomics to handle our pause target.
3811 // It is unclear why this should not include the full pause. We will
3812 // investigate this in CR 7178365.
3813 //
3814 // Preserving the old comment here if that helps the investigation:
3815 //
3816 // The elapsed time induced by the start time below deliberately elides
3817 // the possible verification above.
3818 double sample_start_time_sec = os::elapsedTime();
3819
3820 #if YOUNG_LIST_VERBOSE
3821 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3822 _young_list->print();
3823 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3824 #endif // YOUNG_LIST_VERBOSE
3825
3826 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3827
3828 double scan_wait_start = os::elapsedTime();
3829 // We have to wait until the CM threads finish scanning the
3830 // root regions as it's the only way to ensure that all the
3831 // objects on them have been correctly scanned before we start
3832 // moving them during the GC.
3833 bool waited = _cm->root_regions()->wait_until_scan_finished();
3834 double wait_time_ms = 0.0;
3835 if (waited) {
3836 double scan_wait_end = os::elapsedTime();
3837 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3838 }
3839 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3840
3841 #if YOUNG_LIST_VERBOSE
3842 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3843 _young_list->print();
3844 #endif // YOUNG_LIST_VERBOSE
3845
3846 if (g1_policy()->during_initial_mark_pause()) {
3847 concurrent_mark()->checkpointRootsInitialPre();
3848 }
3849
3850 #if YOUNG_LIST_VERBOSE
3851 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3852 _young_list->print();
3853 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3854 #endif // YOUNG_LIST_VERBOSE
3855
3856 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3857
3858 register_humongous_regions_with_cset();
3859
3860 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3861
3862 _cm->note_start_of_gc();
3863 // We should not verify the per-thread SATB buffers given that
3864 // we have not filtered them yet (we'll do so during the
3865 // GC). We also call this after finalize_cset() to
3866 // ensure that the CSet has been finalized.
3867 _cm->verify_no_cset_oops(true /* verify_stacks */,
3868 true /* verify_enqueued_buffers */,
3869 false /* verify_thread_buffers */,
3870 true /* verify_fingers */);
3871
3872 if (_hr_printer.is_active()) {
3873 HeapRegion* hr = g1_policy()->collection_set();
3874 while (hr != NULL) {
3875 _hr_printer.cset(hr);
3876 hr = hr->next_in_collection_set();
3877 }
3878 }
3879
3880 #ifdef ASSERT
3881 VerifyCSetClosure cl;
3882 collection_set_iterate(&cl);
3883 #endif // ASSERT
3884
3885 setup_surviving_young_words();
3886
3887 // Initialize the GC alloc regions.
3888 _allocator->init_gc_alloc_regions(evacuation_info);
3889
3890 // Actually do the work...
3891 evacuate_collection_set(evacuation_info);
3892
3893 // We do this to mainly verify the per-thread SATB buffers
3894 // (which have been filtered by now) since we didn't verify
3895 // them earlier. No point in re-checking the stacks / enqueued
3896 // buffers given that the CSet has not changed since last time
3897 // we checked.
3898 _cm->verify_no_cset_oops(false /* verify_stacks */,
3899 false /* verify_enqueued_buffers */,
3900 true /* verify_thread_buffers */,
3901 true /* verify_fingers */);
3902
3903 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3904
3905 eagerly_reclaim_humongous_regions();
3906
3907 g1_policy()->clear_collection_set();
3908
3909 cleanup_surviving_young_words();
3910
3911 // Start a new incremental collection set for the next pause.
3912 g1_policy()->start_incremental_cset_building();
3913
3914 clear_cset_fast_test();
3915
3916 _young_list->reset_sampled_info();
3917
3918 // Don't check the whole heap at this point as the
3919 // GC alloc regions from this pause have been tagged
3920 // as survivors and moved on to the survivor list.
3921 // Survivor regions will fail the !is_young() check.
3922 assert(check_young_list_empty(false /* check_heap */),
3923 "young list should be empty");
3924
3925 #if YOUNG_LIST_VERBOSE
3926 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3927 _young_list->print();
3928 #endif // YOUNG_LIST_VERBOSE
3929
3930 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3931 _young_list->first_survivor_region(),
3932 _young_list->last_survivor_region());
3933
3934 _young_list->reset_auxilary_lists();
3935
3936 if (evacuation_failed()) {
3937 _allocator->set_used(recalculate_used());
3938 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3939 for (uint i = 0; i < n_queues; i++) {
3940 if (_evacuation_failed_info_array[i].has_failed()) {
3941 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3942 }
3943 }
3944 } else {
3945 // The "used" of the the collection set have already been subtracted
3946 // when they were freed. Add in the bytes evacuated.
3947 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3948 }
3949
3950 if (g1_policy()->during_initial_mark_pause()) {
3951 // We have to do this before we notify the CM threads that
3952 // they can start working to make sure that all the
3953 // appropriate initialization is done on the CM object.
3954 concurrent_mark()->checkpointRootsInitialPost();
3955 set_marking_started();
3956 // Note that we don't actually trigger the CM thread at
3957 // this point. We do that later when we're sure that
3958 // the current thread has completed its logging output.
3959 }
3960
3961 allocate_dummy_regions();
3962
3963 #if YOUNG_LIST_VERBOSE
3964 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3965 _young_list->print();
3966 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3967 #endif // YOUNG_LIST_VERBOSE
3968
3969 _allocator->init_mutator_alloc_region();
3970
3971 {
3972 size_t expand_bytes = g1_policy()->expansion_amount();
3973 if (expand_bytes > 0) {
3974 size_t bytes_before = capacity();
3975 // No need for an ergo verbose message here,
3976 // expansion_amount() does this when it returns a value > 0.
3977 if (!expand(expand_bytes)) {
3978 // We failed to expand the heap. Cannot do anything about it.
3979 }
3980 }
3981 }
3982
3983 // We redo the verification but now wrt to the new CSet which
3984 // has just got initialized after the previous CSet was freed.
3985 _cm->verify_no_cset_oops(true /* verify_stacks */,
3986 true /* verify_enqueued_buffers */,
3987 true /* verify_thread_buffers */,
3988 true /* verify_fingers */);
3989 _cm->note_end_of_gc();
3990
3991 // This timing is only used by the ergonomics to handle our pause target.
3992 // It is unclear why this should not include the full pause. We will
3993 // investigate this in CR 7178365.
3994 double sample_end_time_sec = os::elapsedTime();
3995 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3996 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3997
3998 MemoryService::track_memory_usage();
3999
4000 // In prepare_for_verify() below we'll need to scan the deferred
4001 // update buffers to bring the RSets up-to-date if
4002 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4003 // the update buffers we'll probably need to scan cards on the
4004 // regions we just allocated to (i.e., the GC alloc
4005 // regions). However, during the last GC we called
4006 // set_saved_mark() on all the GC alloc regions, so card
4007 // scanning might skip the [saved_mark_word()...top()] area of
4008 // those regions (i.e., the area we allocated objects into
4009 // during the last GC). But it shouldn't. Given that
4010 // saved_mark_word() is conditional on whether the GC time stamp
4011 // on the region is current or not, by incrementing the GC time
4012 // stamp here we invalidate all the GC time stamps on all the
4013 // regions and saved_mark_word() will simply return top() for
4014 // all the regions. This is a nicer way of ensuring this rather
4015 // than iterating over the regions and fixing them. In fact, the
4016 // GC time stamp increment here also ensures that
4017 // saved_mark_word() will return top() between pauses, i.e.,
4018 // during concurrent refinement. So we don't need the
4019 // is_gc_active() check to decided which top to use when
4020 // scanning cards (see CR 7039627).
4021 increment_gc_time_stamp();
4022
4023 verify_after_gc();
4024 check_bitmaps("GC End");
4025
4026 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4027 ref_processor_stw()->verify_no_references_recorded();
4028
4029 // CM reference discovery will be re-enabled if necessary.
4030 }
4031
4032 // We should do this after we potentially expand the heap so
4033 // that all the COMMIT events are generated before the end GC
4034 // event, and after we retire the GC alloc regions so that all
4035 // RETIRE events are generated before the end GC event.
4036 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4037
4038 #ifdef TRACESPINNING
4039 ParallelTaskTerminator::print_termination_counts();
4040 #endif
4041
4042 gc_epilogue(false);
4043 }
4044
4045 // Print the remainder of the GC log output.
4046 log_gc_footer(os::elapsedTime() - pause_start_sec);
4047
4048 // It is not yet to safe to tell the concurrent mark to
4049 // start as we have some optional output below. We don't want the
4050 // output from the concurrent mark thread interfering with this
4051 // logging output either.
4052
4053 _hrm.verify_optional();
4054 verify_region_sets_optional();
4055
4056 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4057 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4058
4059 print_heap_after_gc();
4060 trace_heap_after_gc(_gc_tracer_stw);
4061
4062 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4063 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4064 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4065 // before any GC notifications are raised.
4066 g1mm()->update_sizes();
4067
4068 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4069 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4070 _gc_timer_stw->register_gc_end();
4071 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4072 }
4073 // It should now be safe to tell the concurrent mark thread to start
4074 // without its logging output interfering with the logging output
4075 // that came from the pause.
4076
4077 if (should_start_conc_mark) {
4078 // CAUTION: after the doConcurrentMark() call below,
4079 // the concurrent marking thread(s) could be running
4080 // concurrently with us. Make sure that anything after
4081 // this point does not assume that we are the only GC thread
4082 // running. Note: of course, the actual marking work will
4083 // not start until the safepoint itself is released in
4084 // SuspendibleThreadSet::desynchronize().
4085 doConcurrentMark();
4086 }
4087
4088 return true;
4089 }
4090
4091 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4092 _drain_in_progress = false;
4093 set_evac_failure_closure(cl);
4094 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4095 }
4096
4097 void G1CollectedHeap::finalize_for_evac_failure() {
4098 assert(_evac_failure_scan_stack != NULL &&
4099 _evac_failure_scan_stack->length() == 0,
4100 "Postcondition");
4101 assert(!_drain_in_progress, "Postcondition");
4102 delete _evac_failure_scan_stack;
4103 _evac_failure_scan_stack = NULL;
4104 }
4105
4106 void G1CollectedHeap::remove_self_forwarding_pointers() {
4107 double remove_self_forwards_start = os::elapsedTime();
4108
4109 set_par_threads();
4110 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4111 workers()->run_task(&rsfp_task);
4112 set_par_threads(0);
4113
4114 // Now restore saved marks, if any.
4115 assert(_objs_with_preserved_marks.size() ==
4116 _preserved_marks_of_objs.size(), "Both or none.");
4117 while (!_objs_with_preserved_marks.is_empty()) {
4118 oop obj = _objs_with_preserved_marks.pop();
4119 markOop m = _preserved_marks_of_objs.pop();
4120 obj->set_mark(m);
4121 }
4122 _objs_with_preserved_marks.clear(true);
4123 _preserved_marks_of_objs.clear(true);
4124
4125 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4126 }
4127
4128 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4129 _evac_failure_scan_stack->push(obj);
4130 }
4131
4132 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4133 assert(_evac_failure_scan_stack != NULL, "precondition");
4134
4135 while (_evac_failure_scan_stack->length() > 0) {
4136 oop obj = _evac_failure_scan_stack->pop();
4137 _evac_failure_closure->set_region(heap_region_containing(obj));
4138 obj->oop_iterate_backwards(_evac_failure_closure);
4139 }
4140 }
4141
4142 oop
4143 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4144 oop old) {
4145 assert(obj_in_cs(old),
4146 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4147 (HeapWord*) old));
4148 markOop m = old->mark();
4149 oop forward_ptr = old->forward_to_atomic(old);
4150 if (forward_ptr == NULL) {
4151 // Forward-to-self succeeded.
4152 assert(_par_scan_state != NULL, "par scan state");
4153 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4154 uint queue_num = _par_scan_state->queue_num();
4155
4156 _evacuation_failed = true;
4157 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4158 if (_evac_failure_closure != cl) {
4159 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4160 assert(!_drain_in_progress,
4161 "Should only be true while someone holds the lock.");
4162 // Set the global evac-failure closure to the current thread's.
4163 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4164 set_evac_failure_closure(cl);
4165 // Now do the common part.
4166 handle_evacuation_failure_common(old, m);
4167 // Reset to NULL.
4168 set_evac_failure_closure(NULL);
4169 } else {
4170 // The lock is already held, and this is recursive.
4171 assert(_drain_in_progress, "This should only be the recursive case.");
4172 handle_evacuation_failure_common(old, m);
4173 }
4174 return old;
4175 } else {
4176 // Forward-to-self failed. Either someone else managed to allocate
4177 // space for this object (old != forward_ptr) or they beat us in
4178 // self-forwarding it (old == forward_ptr).
4179 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4180 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4181 "should not be in the CSet",
4182 (HeapWord*) old, (HeapWord*) forward_ptr));
4183 return forward_ptr;
4184 }
4185 }
4186
4187 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4188 preserve_mark_if_necessary(old, m);
4189
4190 HeapRegion* r = heap_region_containing(old);
4191 if (!r->evacuation_failed()) {
4192 r->set_evacuation_failed(true);
4193 _hr_printer.evac_failure(r);
4194 }
4195
4196 push_on_evac_failure_scan_stack(old);
4197
4198 if (!_drain_in_progress) {
4199 // prevent recursion in copy_to_survivor_space()
4200 _drain_in_progress = true;
4201 drain_evac_failure_scan_stack();
4202 _drain_in_progress = false;
4203 }
4204 }
4205
4206 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4207 assert(evacuation_failed(), "Oversaving!");
4208 // We want to call the "for_promotion_failure" version only in the
4209 // case of a promotion failure.
4210 if (m->must_be_preserved_for_promotion_failure(obj)) {
4211 _objs_with_preserved_marks.push(obj);
4212 _preserved_marks_of_objs.push(m);
4213 }
4214 }
4215
4216 void G1ParCopyHelper::mark_object(oop obj) {
4217 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4218
4219 // We know that the object is not moving so it's safe to read its size.
4220 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4221 }
4222
4223 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4224 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4225 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4226 assert(from_obj != to_obj, "should not be self-forwarded");
4227
4228 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4229 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4230
4231 // The object might be in the process of being copied by another
4232 // worker so we cannot trust that its to-space image is
4233 // well-formed. So we have to read its size from its from-space
4234 // image which we know should not be changing.
4235 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4236 }
4237
4238 template <class T>
4239 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4240 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4241 _scanned_klass->record_modified_oops();
4242 }
4243 }
4244
4245 template <G1Barrier barrier, G1Mark do_mark_object>
4246 template <class T>
4247 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4248 T heap_oop = oopDesc::load_heap_oop(p);
4249
4250 if (oopDesc::is_null(heap_oop)) {
4251 return;
4252 }
4253
4254 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4255
4256 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4257
4258 const InCSetState state = _g1->in_cset_state(obj);
4259 if (state.is_in_cset()) {
4260 oop forwardee;
4261 markOop m = obj->mark();
4262 if (m->is_marked()) {
4263 forwardee = (oop) m->decode_pointer();
4264 } else {
4265 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4266 }
4267 assert(forwardee != NULL, "forwardee should not be NULL");
4268 oopDesc::encode_store_heap_oop(p, forwardee);
4269 if (do_mark_object != G1MarkNone && forwardee != obj) {
4270 // If the object is self-forwarded we don't need to explicitly
4271 // mark it, the evacuation failure protocol will do so.
4272 mark_forwarded_object(obj, forwardee);
4273 }
4274
4275 if (barrier == G1BarrierKlass) {
4276 do_klass_barrier(p, forwardee);
4277 }
4278 } else {
4279 if (state.is_humongous()) {
4280 _g1->set_humongous_is_live(obj);
4281 }
4282 // The object is not in collection set. If we're a root scanning
4283 // closure during an initial mark pause then attempt to mark the object.
4284 if (do_mark_object == G1MarkFromRoot) {
4285 mark_object(obj);
4286 }
4287 }
4288
4289 if (barrier == G1BarrierEvac) {
4290 _par_scan_state->update_rs(_from, p, _worker_id);
4291 }
4292 }
4293
4294 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4295 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4296
4297 class G1ParEvacuateFollowersClosure : public VoidClosure {
4298 protected:
4299 G1CollectedHeap* _g1h;
4300 G1ParScanThreadState* _par_scan_state;
4301 RefToScanQueueSet* _queues;
4302 ParallelTaskTerminator* _terminator;
4303
4304 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4305 RefToScanQueueSet* queues() { return _queues; }
4306 ParallelTaskTerminator* terminator() { return _terminator; }
4307
4308 public:
4309 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4310 G1ParScanThreadState* par_scan_state,
4311 RefToScanQueueSet* queues,
4312 ParallelTaskTerminator* terminator)
4313 : _g1h(g1h), _par_scan_state(par_scan_state),
4314 _queues(queues), _terminator(terminator) {}
4315
4316 void do_void();
4317
4318 private:
4319 inline bool offer_termination();
4320 };
4321
4322 bool G1ParEvacuateFollowersClosure::offer_termination() {
4323 G1ParScanThreadState* const pss = par_scan_state();
4324 pss->start_term_time();
4325 const bool res = terminator()->offer_termination();
4326 pss->end_term_time();
4327 return res;
4328 }
4329
4330 void G1ParEvacuateFollowersClosure::do_void() {
4331 G1ParScanThreadState* const pss = par_scan_state();
4332 pss->trim_queue();
4333 do {
4334 pss->steal_and_trim_queue(queues());
4335 } while (!offer_termination());
4336 }
4337
4338 class G1KlassScanClosure : public KlassClosure {
4339 G1ParCopyHelper* _closure;
4340 bool _process_only_dirty;
4341 int _count;
4342 public:
4343 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4344 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4345 void do_klass(Klass* klass) {
4346 // If the klass has not been dirtied we know that there's
4347 // no references into the young gen and we can skip it.
4348 if (!_process_only_dirty || klass->has_modified_oops()) {
4349 // Clean the klass since we're going to scavenge all the metadata.
4350 klass->clear_modified_oops();
4351
4352 // Tell the closure that this klass is the Klass to scavenge
4353 // and is the one to dirty if oops are left pointing into the young gen.
4354 _closure->set_scanned_klass(klass);
4355
4356 klass->oops_do(_closure);
4357
4358 _closure->set_scanned_klass(NULL);
4359 }
4360 _count++;
4361 }
4362 };
4363
4364 class G1ParTask : public AbstractGangTask {
4365 protected:
4366 G1CollectedHeap* _g1h;
4367 RefToScanQueueSet *_queues;
4368 G1RootProcessor* _root_processor;
4369 ParallelTaskTerminator _terminator;
4370 uint _n_workers;
4371
4372 Mutex _stats_lock;
4373 Mutex* stats_lock() { return &_stats_lock; }
4374
4375 public:
4376 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4377 : AbstractGangTask("G1 collection"),
4378 _g1h(g1h),
4379 _queues(task_queues),
4380 _root_processor(root_processor),
4381 _terminator(0, _queues),
4382 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4383 {}
4384
4385 RefToScanQueueSet* queues() { return _queues; }
4386
4387 RefToScanQueue *work_queue(int i) {
4388 return queues()->queue(i);
4389 }
4390
4391 ParallelTaskTerminator* terminator() { return &_terminator; }
4392
4393 virtual void set_for_termination(int active_workers) {
4394 _root_processor->set_num_workers(active_workers);
4395 terminator()->reset_for_reuse(active_workers);
4396 _n_workers = active_workers;
4397 }
4398
4399 // Helps out with CLD processing.
4400 //
4401 // During InitialMark we need to:
4402 // 1) Scavenge all CLDs for the young GC.
4403 // 2) Mark all objects directly reachable from strong CLDs.
4404 template <G1Mark do_mark_object>
4405 class G1CLDClosure : public CLDClosure {
4406 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4407 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4408 G1KlassScanClosure _klass_in_cld_closure;
4409 bool _claim;
4410
4411 public:
4412 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4413 bool only_young, bool claim)
4414 : _oop_closure(oop_closure),
4415 _oop_in_klass_closure(oop_closure->g1(),
4416 oop_closure->pss(),
4417 oop_closure->rp()),
4418 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4419 _claim(claim) {
4420
4421 }
4422
4423 void do_cld(ClassLoaderData* cld) {
4424 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4425 }
4426 };
4427
4428 void work(uint worker_id) {
4429 if (worker_id >= _n_workers) return; // no work needed this round
4430
4431 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4432
4433 {
4434 ResourceMark rm;
4435 HandleMark hm;
4436
4437 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4438
4439 G1ParScanThreadState pss(_g1h, worker_id, rp);
4440 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4441
4442 pss.set_evac_failure_closure(&evac_failure_cl);
4443
4444 bool only_young = _g1h->g1_policy()->gcs_are_young();
4445
4446 // Non-IM young GC.
4447 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4448 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4449 only_young, // Only process dirty klasses.
4450 false); // No need to claim CLDs.
4451 // IM young GC.
4452 // Strong roots closures.
4453 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4454 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4455 false, // Process all klasses.
4456 true); // Need to claim CLDs.
4457 // Weak roots closures.
4458 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4459 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4460 false, // Process all klasses.
4461 true); // Need to claim CLDs.
4462
4463 OopClosure* strong_root_cl;
4464 OopClosure* weak_root_cl;
4465 CLDClosure* strong_cld_cl;
4466 CLDClosure* weak_cld_cl;
4467
4468 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4469 // We also need to mark copied objects.
4470 strong_root_cl = &scan_mark_root_cl;
4471 strong_cld_cl = &scan_mark_cld_cl;
4472 if (ClassUnloadingWithConcurrentMark) {
4473 weak_root_cl = &scan_mark_weak_root_cl;
4474 weak_cld_cl = &scan_mark_weak_cld_cl;
4475 } else {
4476 weak_root_cl = &scan_mark_root_cl;
4477 weak_cld_cl = &scan_mark_cld_cl;
4478 }
4479 } else {
4480 strong_root_cl = &scan_only_root_cl;
4481 weak_root_cl = &scan_only_root_cl;
4482 strong_cld_cl = &scan_only_cld_cl;
4483 weak_cld_cl = &scan_only_cld_cl;
4484 }
4485
4486 pss.start_strong_roots();
4487
4488 _root_processor->evacuate_roots(strong_root_cl,
4489 weak_root_cl,
4490 strong_cld_cl,
4491 weak_cld_cl,
4492 worker_id);
4493
4494 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4495 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4496 weak_root_cl,
4497 worker_id);
4498 pss.end_strong_roots();
4499
4500 {
4501 double start = os::elapsedTime();
4502 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4503 evac.do_void();
4504 double elapsed_sec = os::elapsedTime() - start;
4505 double term_sec = pss.term_time();
4506 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4507 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4508 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4509 }
4510 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4511 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4512
4513 if (PrintTerminationStats) {
4514 MutexLocker x(stats_lock());
4515 pss.print_termination_stats(worker_id);
4516 }
4517
4518 assert(pss.queue_is_empty(), "should be empty");
4519
4520 // Close the inner scope so that the ResourceMark and HandleMark
4521 // destructors are executed here and are included as part of the
4522 // "GC Worker Time".
4523 }
4524 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4525 }
4526 };
4527
4528 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4529 private:
4530 BoolObjectClosure* _is_alive;
4531 int _initial_string_table_size;
4532 int _initial_symbol_table_size;
4533
4534 bool _process_strings;
4535 int _strings_processed;
4536 int _strings_removed;
4537
4538 bool _process_symbols;
4539 int _symbols_processed;
4540 int _symbols_removed;
4541
4542 public:
4543 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4544 AbstractGangTask("String/Symbol Unlinking"),
4545 _is_alive(is_alive),
4546 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4547 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4548
4549 _initial_string_table_size = StringTable::the_table()->table_size();
4550 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4551 if (process_strings) {
4552 StringTable::clear_parallel_claimed_index();
4553 }
4554 if (process_symbols) {
4555 SymbolTable::clear_parallel_claimed_index();
4556 }
4557 }
4558
4559 ~G1StringSymbolTableUnlinkTask() {
4560 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4561 err_msg("claim value %d after unlink less than initial string table size %d",
4562 StringTable::parallel_claimed_index(), _initial_string_table_size));
4563 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4564 err_msg("claim value %d after unlink less than initial symbol table size %d",
4565 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4566
4567 if (G1TraceStringSymbolTableScrubbing) {
4568 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4569 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4570 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4571 strings_processed(), strings_removed(),
4572 symbols_processed(), symbols_removed());
4573 }
4574 }
4575
4576 void work(uint worker_id) {
4577 int strings_processed = 0;
4578 int strings_removed = 0;
4579 int symbols_processed = 0;
4580 int symbols_removed = 0;
4581 if (_process_strings) {
4582 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4583 Atomic::add(strings_processed, &_strings_processed);
4584 Atomic::add(strings_removed, &_strings_removed);
4585 }
4586 if (_process_symbols) {
4587 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4588 Atomic::add(symbols_processed, &_symbols_processed);
4589 Atomic::add(symbols_removed, &_symbols_removed);
4590 }
4591 }
4592
4593 size_t strings_processed() const { return (size_t)_strings_processed; }
4594 size_t strings_removed() const { return (size_t)_strings_removed; }
4595
4596 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4597 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4598 };
4599
4600 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4601 private:
4602 static Monitor* _lock;
4603
4604 BoolObjectClosure* const _is_alive;
4605 const bool _unloading_occurred;
4606 const uint _num_workers;
4607
4608 // Variables used to claim nmethods.
4609 nmethod* _first_nmethod;
4610 volatile nmethod* _claimed_nmethod;
4611
4612 // The list of nmethods that need to be processed by the second pass.
4613 volatile nmethod* _postponed_list;
4614 volatile uint _num_entered_barrier;
4615
4616 public:
4617 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4618 _is_alive(is_alive),
4619 _unloading_occurred(unloading_occurred),
4620 _num_workers(num_workers),
4621 _first_nmethod(NULL),
4622 _claimed_nmethod(NULL),
4623 _postponed_list(NULL),
4624 _num_entered_barrier(0)
4625 {
4626 nmethod::increase_unloading_clock();
4627 // Get first alive nmethod
4628 NMethodIterator iter = NMethodIterator();
4629 if(iter.next_alive()) {
4630 _first_nmethod = iter.method();
4631 }
4632 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4633 }
4634
4635 ~G1CodeCacheUnloadingTask() {
4636 CodeCache::verify_clean_inline_caches();
4637
4638 CodeCache::set_needs_cache_clean(false);
4639 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4640
4641 CodeCache::verify_icholder_relocations();
4642 }
4643
4644 private:
4645 void add_to_postponed_list(nmethod* nm) {
4646 nmethod* old;
4647 do {
4648 old = (nmethod*)_postponed_list;
4649 nm->set_unloading_next(old);
4650 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4651 }
4652
4653 void clean_nmethod(nmethod* nm) {
4654 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4655
4656 if (postponed) {
4657 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4658 add_to_postponed_list(nm);
4659 }
4660
4661 // Mark that this thread has been cleaned/unloaded.
4662 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4663 nm->set_unloading_clock(nmethod::global_unloading_clock());
4664 }
4665
4666 void clean_nmethod_postponed(nmethod* nm) {
4667 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4668 }
4669
4670 static const int MaxClaimNmethods = 16;
4671
4672 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4673 nmethod* first;
4674 NMethodIterator last;
4675
4676 do {
4677 *num_claimed_nmethods = 0;
4678
4679 first = (nmethod*)_claimed_nmethod;
4680 last = NMethodIterator(first);
4681
4682 if (first != NULL) {
4683
4684 for (int i = 0; i < MaxClaimNmethods; i++) {
4685 if (!last.next_alive()) {
4686 break;
4687 }
4688 claimed_nmethods[i] = last.method();
4689 (*num_claimed_nmethods)++;
4690 }
4691 }
4692
4693 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4694 }
4695
4696 nmethod* claim_postponed_nmethod() {
4697 nmethod* claim;
4698 nmethod* next;
4699
4700 do {
4701 claim = (nmethod*)_postponed_list;
4702 if (claim == NULL) {
4703 return NULL;
4704 }
4705
4706 next = claim->unloading_next();
4707
4708 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4709
4710 return claim;
4711 }
4712
4713 public:
4714 // Mark that we're done with the first pass of nmethod cleaning.
4715 void barrier_mark(uint worker_id) {
4716 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4717 _num_entered_barrier++;
4718 if (_num_entered_barrier == _num_workers) {
4719 ml.notify_all();
4720 }
4721 }
4722
4723 // See if we have to wait for the other workers to
4724 // finish their first-pass nmethod cleaning work.
4725 void barrier_wait(uint worker_id) {
4726 if (_num_entered_barrier < _num_workers) {
4727 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4728 while (_num_entered_barrier < _num_workers) {
4729 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4730 }
4731 }
4732 }
4733
4734 // Cleaning and unloading of nmethods. Some work has to be postponed
4735 // to the second pass, when we know which nmethods survive.
4736 void work_first_pass(uint worker_id) {
4737 // The first nmethods is claimed by the first worker.
4738 if (worker_id == 0 && _first_nmethod != NULL) {
4739 clean_nmethod(_first_nmethod);
4740 _first_nmethod = NULL;
4741 }
4742
4743 int num_claimed_nmethods;
4744 nmethod* claimed_nmethods[MaxClaimNmethods];
4745
4746 while (true) {
4747 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4748
4749 if (num_claimed_nmethods == 0) {
4750 break;
4751 }
4752
4753 for (int i = 0; i < num_claimed_nmethods; i++) {
4754 clean_nmethod(claimed_nmethods[i]);
4755 }
4756 }
4757
4758 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4759 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4760 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4761 }
4762
4763 void work_second_pass(uint worker_id) {
4764 nmethod* nm;
4765 // Take care of postponed nmethods.
4766 while ((nm = claim_postponed_nmethod()) != NULL) {
4767 clean_nmethod_postponed(nm);
4768 }
4769 }
4770 };
4771
4772 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4773
4774 class G1KlassCleaningTask : public StackObj {
4775 BoolObjectClosure* _is_alive;
4776 volatile jint _clean_klass_tree_claimed;
4777 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4778
4779 public:
4780 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4781 _is_alive(is_alive),
4782 _clean_klass_tree_claimed(0),
4783 _klass_iterator() {
4784 }
4785
4786 private:
4787 bool claim_clean_klass_tree_task() {
4788 if (_clean_klass_tree_claimed) {
4789 return false;
4790 }
4791
4792 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4793 }
4794
4795 InstanceKlass* claim_next_klass() {
4796 Klass* klass;
4797 do {
4798 klass =_klass_iterator.next_klass();
4799 } while (klass != NULL && !klass->oop_is_instance());
4800
4801 return (InstanceKlass*)klass;
4802 }
4803
4804 public:
4805
4806 void clean_klass(InstanceKlass* ik) {
4807 ik->clean_implementors_list(_is_alive);
4808 ik->clean_method_data(_is_alive);
4809
4810 // G1 specific cleanup work that has
4811 // been moved here to be done in parallel.
4812 ik->clean_dependent_nmethods();
4813 if (JvmtiExport::has_redefined_a_class()) {
4814 InstanceKlass::purge_previous_versions(ik);
4815 }
4816 }
4817
4818 void work() {
4819 ResourceMark rm;
4820
4821 // One worker will clean the subklass/sibling klass tree.
4822 if (claim_clean_klass_tree_task()) {
4823 Klass::clean_subklass_tree(_is_alive);
4824 }
4825
4826 // All workers will help cleaning the classes,
4827 InstanceKlass* klass;
4828 while ((klass = claim_next_klass()) != NULL) {
4829 clean_klass(klass);
4830 }
4831 }
4832 };
4833
4834 // To minimize the remark pause times, the tasks below are done in parallel.
4835 class G1ParallelCleaningTask : public AbstractGangTask {
4836 private:
4837 G1StringSymbolTableUnlinkTask _string_symbol_task;
4838 G1CodeCacheUnloadingTask _code_cache_task;
4839 G1KlassCleaningTask _klass_cleaning_task;
4840
4841 public:
4842 // The constructor is run in the VMThread.
4843 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4844 AbstractGangTask("Parallel Cleaning"),
4845 _string_symbol_task(is_alive, process_strings, process_symbols),
4846 _code_cache_task(num_workers, is_alive, unloading_occurred),
4847 _klass_cleaning_task(is_alive) {
4848 }
4849
4850 void pre_work_verification() {
4851 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4852 }
4853
4854 void post_work_verification() {
4855 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4856 }
4857
4858 // The parallel work done by all worker threads.
4859 void work(uint worker_id) {
4860 pre_work_verification();
4861
4862 // Do first pass of code cache cleaning.
4863 _code_cache_task.work_first_pass(worker_id);
4864
4865 // Let the threads mark that the first pass is done.
4866 _code_cache_task.barrier_mark(worker_id);
4867
4868 // Clean the Strings and Symbols.
4869 _string_symbol_task.work(worker_id);
4870
4871 // Wait for all workers to finish the first code cache cleaning pass.
4872 _code_cache_task.barrier_wait(worker_id);
4873
4874 // Do the second code cache cleaning work, which realize on
4875 // the liveness information gathered during the first pass.
4876 _code_cache_task.work_second_pass(worker_id);
4877
4878 // Clean all klasses that were not unloaded.
4879 _klass_cleaning_task.work();
4880
4881 post_work_verification();
4882 }
4883 };
4884
4885
4886 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4887 bool process_strings,
4888 bool process_symbols,
4889 bool class_unloading_occurred) {
4890 uint n_workers = workers()->active_workers();
4891
4892 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4893 n_workers, class_unloading_occurred);
4894 set_par_threads(n_workers);
4895 workers()->run_task(&g1_unlink_task);
4896 set_par_threads(0);
4897 }
4898
4899 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4900 bool process_strings, bool process_symbols) {
4901 {
4902 uint n_workers = _g1h->workers()->active_workers();
4903 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4904 set_par_threads(n_workers);
4905 workers()->run_task(&g1_unlink_task);
4906 set_par_threads(0);
4907 }
4908
4909 if (G1StringDedup::is_enabled()) {
4910 G1StringDedup::unlink(is_alive);
4911 }
4912 }
4913
4914 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4915 private:
4916 DirtyCardQueueSet* _queue;
4917 public:
4918 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4919
4920 virtual void work(uint worker_id) {
4921 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4922 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4923
4924 RedirtyLoggedCardTableEntryClosure cl;
4925 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4926
4927 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4928 }
4929 };
4930
4931 void G1CollectedHeap::redirty_logged_cards() {
4932 double redirty_logged_cards_start = os::elapsedTime();
4933
4934 uint n_workers = _g1h->workers()->active_workers();
4935
4936 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4937 dirty_card_queue_set().reset_for_par_iteration();
4938 set_par_threads(n_workers);
4939 workers()->run_task(&redirty_task);
4940 set_par_threads(0);
4941
4942 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4943 dcq.merge_bufferlists(&dirty_card_queue_set());
4944 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4945
4946 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4947 }
4948
4949 // Weak Reference Processing support
4950
4951 // An always "is_alive" closure that is used to preserve referents.
4952 // If the object is non-null then it's alive. Used in the preservation
4953 // of referent objects that are pointed to by reference objects
4954 // discovered by the CM ref processor.
4955 class G1AlwaysAliveClosure: public BoolObjectClosure {
4956 G1CollectedHeap* _g1;
4957 public:
4958 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4959 bool do_object_b(oop p) {
4960 if (p != NULL) {
4961 return true;
4962 }
4963 return false;
4964 }
4965 };
4966
4967 bool G1STWIsAliveClosure::do_object_b(oop p) {
4968 // An object is reachable if it is outside the collection set,
4969 // or is inside and copied.
4970 return !_g1->obj_in_cs(p) || p->is_forwarded();
4971 }
4972
4973 // Non Copying Keep Alive closure
4974 class G1KeepAliveClosure: public OopClosure {
4975 G1CollectedHeap* _g1;
4976 public:
4977 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4978 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4979 void do_oop(oop* p) {
4980 oop obj = *p;
4981 assert(obj != NULL, "the caller should have filtered out NULL values");
4982
4983 const InCSetState cset_state = _g1->in_cset_state(obj);
4984 if (!cset_state.is_in_cset_or_humongous()) {
4985 return;
4986 }
4987 if (cset_state.is_in_cset()) {
4988 assert( obj->is_forwarded(), "invariant" );
4989 *p = obj->forwardee();
4990 } else {
4991 assert(!obj->is_forwarded(), "invariant" );
4992 assert(cset_state.is_humongous(),
4993 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4994 _g1->set_humongous_is_live(obj);
4995 }
4996 }
4997 };
4998
4999 // Copying Keep Alive closure - can be called from both
5000 // serial and parallel code as long as different worker
5001 // threads utilize different G1ParScanThreadState instances
5002 // and different queues.
5003
5004 class G1CopyingKeepAliveClosure: public OopClosure {
5005 G1CollectedHeap* _g1h;
5006 OopClosure* _copy_non_heap_obj_cl;
5007 G1ParScanThreadState* _par_scan_state;
5008
5009 public:
5010 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5011 OopClosure* non_heap_obj_cl,
5012 G1ParScanThreadState* pss):
5013 _g1h(g1h),
5014 _copy_non_heap_obj_cl(non_heap_obj_cl),
5015 _par_scan_state(pss)
5016 {}
5017
5018 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5019 virtual void do_oop( oop* p) { do_oop_work(p); }
5020
5021 template <class T> void do_oop_work(T* p) {
5022 oop obj = oopDesc::load_decode_heap_oop(p);
5023
5024 if (_g1h->is_in_cset_or_humongous(obj)) {
5025 // If the referent object has been forwarded (either copied
5026 // to a new location or to itself in the event of an
5027 // evacuation failure) then we need to update the reference
5028 // field and, if both reference and referent are in the G1
5029 // heap, update the RSet for the referent.
5030 //
5031 // If the referent has not been forwarded then we have to keep
5032 // it alive by policy. Therefore we have copy the referent.
5033 //
5034 // If the reference field is in the G1 heap then we can push
5035 // on the PSS queue. When the queue is drained (after each
5036 // phase of reference processing) the object and it's followers
5037 // will be copied, the reference field set to point to the
5038 // new location, and the RSet updated. Otherwise we need to
5039 // use the the non-heap or metadata closures directly to copy
5040 // the referent object and update the pointer, while avoiding
5041 // updating the RSet.
5042
5043 if (_g1h->is_in_g1_reserved(p)) {
5044 _par_scan_state->push_on_queue(p);
5045 } else {
5046 assert(!Metaspace::contains((const void*)p),
5047 err_msg("Unexpectedly found a pointer from metadata: "
5048 PTR_FORMAT, p));
5049 _copy_non_heap_obj_cl->do_oop(p);
5050 }
5051 }
5052 }
5053 };
5054
5055 // Serial drain queue closure. Called as the 'complete_gc'
5056 // closure for each discovered list in some of the
5057 // reference processing phases.
5058
5059 class G1STWDrainQueueClosure: public VoidClosure {
5060 protected:
5061 G1CollectedHeap* _g1h;
5062 G1ParScanThreadState* _par_scan_state;
5063
5064 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5065
5066 public:
5067 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5068 _g1h(g1h),
5069 _par_scan_state(pss)
5070 { }
5071
5072 void do_void() {
5073 G1ParScanThreadState* const pss = par_scan_state();
5074 pss->trim_queue();
5075 }
5076 };
5077
5078 // Parallel Reference Processing closures
5079
5080 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5081 // processing during G1 evacuation pauses.
5082
5083 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5084 private:
5085 G1CollectedHeap* _g1h;
5086 RefToScanQueueSet* _queues;
5087 FlexibleWorkGang* _workers;
5088 int _active_workers;
5089
5090 public:
5091 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5092 FlexibleWorkGang* workers,
5093 RefToScanQueueSet *task_queues,
5094 int n_workers) :
5095 _g1h(g1h),
5096 _queues(task_queues),
5097 _workers(workers),
5098 _active_workers(n_workers)
5099 {
5100 assert(n_workers > 0, "shouldn't call this otherwise");
5101 }
5102
5103 // Executes the given task using concurrent marking worker threads.
5104 virtual void execute(ProcessTask& task);
5105 virtual void execute(EnqueueTask& task);
5106 };
5107
5108 // Gang task for possibly parallel reference processing
5109
5110 class G1STWRefProcTaskProxy: public AbstractGangTask {
5111 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5112 ProcessTask& _proc_task;
5113 G1CollectedHeap* _g1h;
5114 RefToScanQueueSet *_task_queues;
5115 ParallelTaskTerminator* _terminator;
5116
5117 public:
5118 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5119 G1CollectedHeap* g1h,
5120 RefToScanQueueSet *task_queues,
5121 ParallelTaskTerminator* terminator) :
5122 AbstractGangTask("Process reference objects in parallel"),
5123 _proc_task(proc_task),
5124 _g1h(g1h),
5125 _task_queues(task_queues),
5126 _terminator(terminator)
5127 {}
5128
5129 virtual void work(uint worker_id) {
5130 // The reference processing task executed by a single worker.
5131 ResourceMark rm;
5132 HandleMark hm;
5133
5134 G1STWIsAliveClosure is_alive(_g1h);
5135
5136 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5137 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5138
5139 pss.set_evac_failure_closure(&evac_failure_cl);
5140
5141 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5142
5143 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5144
5145 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5146
5147 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5148 // We also need to mark copied objects.
5149 copy_non_heap_cl = ©_mark_non_heap_cl;
5150 }
5151
5152 // Keep alive closure.
5153 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5154
5155 // Complete GC closure
5156 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5157
5158 // Call the reference processing task's work routine.
5159 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5160
5161 // Note we cannot assert that the refs array is empty here as not all
5162 // of the processing tasks (specifically phase2 - pp2_work) execute
5163 // the complete_gc closure (which ordinarily would drain the queue) so
5164 // the queue may not be empty.
5165 }
5166 };
5167
5168 // Driver routine for parallel reference processing.
5169 // Creates an instance of the ref processing gang
5170 // task and has the worker threads execute it.
5171 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5172 assert(_workers != NULL, "Need parallel worker threads.");
5173
5174 ParallelTaskTerminator terminator(_active_workers, _queues);
5175 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5176
5177 _g1h->set_par_threads(_active_workers);
5178 _workers->run_task(&proc_task_proxy);
5179 _g1h->set_par_threads(0);
5180 }
5181
5182 // Gang task for parallel reference enqueueing.
5183
5184 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5185 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5186 EnqueueTask& _enq_task;
5187
5188 public:
5189 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5190 AbstractGangTask("Enqueue reference objects in parallel"),
5191 _enq_task(enq_task)
5192 { }
5193
5194 virtual void work(uint worker_id) {
5195 _enq_task.work(worker_id);
5196 }
5197 };
5198
5199 // Driver routine for parallel reference enqueueing.
5200 // Creates an instance of the ref enqueueing gang
5201 // task and has the worker threads execute it.
5202
5203 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5204 assert(_workers != NULL, "Need parallel worker threads.");
5205
5206 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5207
5208 _g1h->set_par_threads(_active_workers);
5209 _workers->run_task(&enq_task_proxy);
5210 _g1h->set_par_threads(0);
5211 }
5212
5213 // End of weak reference support closures
5214
5215 // Abstract task used to preserve (i.e. copy) any referent objects
5216 // that are in the collection set and are pointed to by reference
5217 // objects discovered by the CM ref processor.
5218
5219 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5220 protected:
5221 G1CollectedHeap* _g1h;
5222 RefToScanQueueSet *_queues;
5223 ParallelTaskTerminator _terminator;
5224 uint _n_workers;
5225
5226 public:
5227 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5228 AbstractGangTask("ParPreserveCMReferents"),
5229 _g1h(g1h),
5230 _queues(task_queues),
5231 _terminator(workers, _queues),
5232 _n_workers(workers)
5233 { }
5234
5235 void work(uint worker_id) {
5236 ResourceMark rm;
5237 HandleMark hm;
5238
5239 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5240 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5241
5242 pss.set_evac_failure_closure(&evac_failure_cl);
5243
5244 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5245
5246 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5247
5248 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5249
5250 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5251
5252 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5253 // We also need to mark copied objects.
5254 copy_non_heap_cl = ©_mark_non_heap_cl;
5255 }
5256
5257 // Is alive closure
5258 G1AlwaysAliveClosure always_alive(_g1h);
5259
5260 // Copying keep alive closure. Applied to referent objects that need
5261 // to be copied.
5262 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5263
5264 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5265
5266 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5267 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5268
5269 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5270 // So this must be true - but assert just in case someone decides to
5271 // change the worker ids.
5272 assert(0 <= worker_id && worker_id < limit, "sanity");
5273 assert(!rp->discovery_is_atomic(), "check this code");
5274
5275 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5276 for (uint idx = worker_id; idx < limit; idx += stride) {
5277 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5278
5279 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5280 while (iter.has_next()) {
5281 // Since discovery is not atomic for the CM ref processor, we
5282 // can see some null referent objects.
5283 iter.load_ptrs(DEBUG_ONLY(true));
5284 oop ref = iter.obj();
5285
5286 // This will filter nulls.
5287 if (iter.is_referent_alive()) {
5288 iter.make_referent_alive();
5289 }
5290 iter.move_to_next();
5291 }
5292 }
5293
5294 // Drain the queue - which may cause stealing
5295 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5296 drain_queue.do_void();
5297 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5298 assert(pss.queue_is_empty(), "should be");
5299 }
5300 };
5301
5302 // Weak Reference processing during an evacuation pause (part 1).
5303 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5304 double ref_proc_start = os::elapsedTime();
5305
5306 ReferenceProcessor* rp = _ref_processor_stw;
5307 assert(rp->discovery_enabled(), "should have been enabled");
5308
5309 // Any reference objects, in the collection set, that were 'discovered'
5310 // by the CM ref processor should have already been copied (either by
5311 // applying the external root copy closure to the discovered lists, or
5312 // by following an RSet entry).
5313 //
5314 // But some of the referents, that are in the collection set, that these
5315 // reference objects point to may not have been copied: the STW ref
5316 // processor would have seen that the reference object had already
5317 // been 'discovered' and would have skipped discovering the reference,
5318 // but would not have treated the reference object as a regular oop.
5319 // As a result the copy closure would not have been applied to the
5320 // referent object.
5321 //
5322 // We need to explicitly copy these referent objects - the references
5323 // will be processed at the end of remarking.
5324 //
5325 // We also need to do this copying before we process the reference
5326 // objects discovered by the STW ref processor in case one of these
5327 // referents points to another object which is also referenced by an
5328 // object discovered by the STW ref processor.
5329
5330 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5331
5332 set_par_threads(no_of_gc_workers);
5333 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5334 no_of_gc_workers,
5335 _task_queues);
5336
5337 workers()->run_task(&keep_cm_referents);
5338
5339 set_par_threads(0);
5340
5341 // Closure to test whether a referent is alive.
5342 G1STWIsAliveClosure is_alive(this);
5343
5344 // Even when parallel reference processing is enabled, the processing
5345 // of JNI refs is serial and performed serially by the current thread
5346 // rather than by a worker. The following PSS will be used for processing
5347 // JNI refs.
5348
5349 // Use only a single queue for this PSS.
5350 G1ParScanThreadState pss(this, 0, NULL);
5351
5352 // We do not embed a reference processor in the copying/scanning
5353 // closures while we're actually processing the discovered
5354 // reference objects.
5355 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5356
5357 pss.set_evac_failure_closure(&evac_failure_cl);
5358
5359 assert(pss.queue_is_empty(), "pre-condition");
5360
5361 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5362
5363 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5364
5365 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5366
5367 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5368 // We also need to mark copied objects.
5369 copy_non_heap_cl = ©_mark_non_heap_cl;
5370 }
5371
5372 // Keep alive closure.
5373 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5374
5375 // Serial Complete GC closure
5376 G1STWDrainQueueClosure drain_queue(this, &pss);
5377
5378 // Setup the soft refs policy...
5379 rp->setup_policy(false);
5380
5381 ReferenceProcessorStats stats;
5382 if (!rp->processing_is_mt()) {
5383 // Serial reference processing...
5384 stats = rp->process_discovered_references(&is_alive,
5385 &keep_alive,
5386 &drain_queue,
5387 NULL,
5388 _gc_timer_stw,
5389 _gc_tracer_stw->gc_id());
5390 } else {
5391 // Parallel reference processing
5392 assert(rp->num_q() == no_of_gc_workers, "sanity");
5393 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5394
5395 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5396 stats = rp->process_discovered_references(&is_alive,
5397 &keep_alive,
5398 &drain_queue,
5399 &par_task_executor,
5400 _gc_timer_stw,
5401 _gc_tracer_stw->gc_id());
5402 }
5403
5404 _gc_tracer_stw->report_gc_reference_stats(stats);
5405
5406 // We have completed copying any necessary live referent objects.
5407 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5408
5409 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5410 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5411 }
5412
5413 // Weak Reference processing during an evacuation pause (part 2).
5414 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5415 double ref_enq_start = os::elapsedTime();
5416
5417 ReferenceProcessor* rp = _ref_processor_stw;
5418 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5419
5420 // Now enqueue any remaining on the discovered lists on to
5421 // the pending list.
5422 if (!rp->processing_is_mt()) {
5423 // Serial reference processing...
5424 rp->enqueue_discovered_references();
5425 } else {
5426 // Parallel reference enqueueing
5427
5428 assert(no_of_gc_workers == workers()->active_workers(),
5429 "Need to reset active workers");
5430 assert(rp->num_q() == no_of_gc_workers, "sanity");
5431 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5432
5433 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5434 rp->enqueue_discovered_references(&par_task_executor);
5435 }
5436
5437 rp->verify_no_references_recorded();
5438 assert(!rp->discovery_enabled(), "should have been disabled");
5439
5440 // FIXME
5441 // CM's reference processing also cleans up the string and symbol tables.
5442 // Should we do that here also? We could, but it is a serial operation
5443 // and could significantly increase the pause time.
5444
5445 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5446 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5447 }
5448
5449 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5450 _expand_heap_after_alloc_failure = true;
5451 _evacuation_failed = false;
5452
5453 // Should G1EvacuationFailureALot be in effect for this GC?
5454 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5455
5456 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5457
5458 // Disable the hot card cache.
5459 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5460 hot_card_cache->reset_hot_cache_claimed_index();
5461 hot_card_cache->set_use_cache(false);
5462
5463 uint n_workers;
5464 n_workers =
5465 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5466 workers()->active_workers(),
5467 Threads::number_of_non_daemon_threads());
5468 assert(UseDynamicNumberOfGCThreads ||
5469 n_workers == workers()->total_workers(),
5470 "If not dynamic should be using all the workers");
5471 workers()->set_active_workers(n_workers);
5472 set_par_threads(n_workers);
5473
5474
5475 init_for_evac_failure(NULL);
5476
5477 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5478 double start_par_time_sec = os::elapsedTime();
5479 double end_par_time_sec;
5480
5481 {
5482 const bool during_im = g1_policy()->during_initial_mark_pause();
5483 const bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
5484
5485 G1RootProcessor root_processor(this, trace_metadata);
5486 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5487 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5488 if (during_im) {
5489 ClassLoaderDataGraph::clear_claimed_marks();
5490 }
5491
5492 // The individual threads will set their evac-failure closures.
5493 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5494 // These tasks use ShareHeap::_process_strong_tasks
5495 assert(UseDynamicNumberOfGCThreads ||
5496 workers()->active_workers() == workers()->total_workers(),
5497 "If not dynamic should be using all the workers");
5498 workers()->run_task(&g1_par_task);
5499 end_par_time_sec = os::elapsedTime();
5500
5501 // Closing the inner scope will execute the destructor
5502 // for the StrongRootsScope object. We record the current
5503 // elapsed time before closing the scope so that time
5504 // taken for the SRS destructor is NOT included in the
5505 // reported parallel time.
5506 }
5507
5508 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5509
5510 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5511 phase_times->record_par_time(par_time_ms);
5512
5513 double code_root_fixup_time_ms =
5514 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5515 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5516
5517 set_par_threads(0);
5518
5519 // Process any discovered reference objects - we have
5520 // to do this _before_ we retire the GC alloc regions
5521 // as we may have to copy some 'reachable' referent
5522 // objects (and their reachable sub-graphs) that were
5523 // not copied during the pause.
5524 process_discovered_references(n_workers);
5525
5526 if (G1StringDedup::is_enabled()) {
5527 double fixup_start = os::elapsedTime();
5528
5529 G1STWIsAliveClosure is_alive(this);
5530 G1KeepAliveClosure keep_alive(this);
5531 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5532
5533 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5534 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5535 }
5536
5537 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5538 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5539
5540 // Reset and re-enable the hot card cache.
5541 // Note the counts for the cards in the regions in the
5542 // collection set are reset when the collection set is freed.
5543 hot_card_cache->reset_hot_cache();
5544 hot_card_cache->set_use_cache(true);
5545
5546 purge_code_root_memory();
5547
5548 finalize_for_evac_failure();
5549
5550 if (evacuation_failed()) {
5551 remove_self_forwarding_pointers();
5552
5553 // Reset the G1EvacuationFailureALot counters and flags
5554 // Note: the values are reset only when an actual
5555 // evacuation failure occurs.
5556 NOT_PRODUCT(reset_evacuation_should_fail();)
5557 }
5558
5559 // Enqueue any remaining references remaining on the STW
5560 // reference processor's discovered lists. We need to do
5561 // this after the card table is cleaned (and verified) as
5562 // the act of enqueueing entries on to the pending list
5563 // will log these updates (and dirty their associated
5564 // cards). We need these updates logged to update any
5565 // RSets.
5566 enqueue_discovered_references(n_workers);
5567
5568 redirty_logged_cards();
5569 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5570 }
5571
5572 void G1CollectedHeap::free_region(HeapRegion* hr,
5573 FreeRegionList* free_list,
5574 bool par,
5575 bool locked) {
5576 assert(!hr->is_free(), "the region should not be free");
5577 assert(!hr->is_empty(), "the region should not be empty");
5578 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5579 assert(free_list != NULL, "pre-condition");
5580
5581 if (G1VerifyBitmaps) {
5582 MemRegion mr(hr->bottom(), hr->end());
5583 concurrent_mark()->clearRangePrevBitmap(mr);
5584 }
5585
5586 // Clear the card counts for this region.
5587 // Note: we only need to do this if the region is not young
5588 // (since we don't refine cards in young regions).
5589 if (!hr->is_young()) {
5590 _cg1r->hot_card_cache()->reset_card_counts(hr);
5591 }
5592 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5593 free_list->add_ordered(hr);
5594 }
5595
5596 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5597 FreeRegionList* free_list,
5598 bool par) {
5599 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5600 assert(free_list != NULL, "pre-condition");
5601
5602 size_t hr_capacity = hr->capacity();
5603 // We need to read this before we make the region non-humongous,
5604 // otherwise the information will be gone.
5605 uint last_index = hr->last_hc_index();
5606 hr->clear_humongous();
5607 free_region(hr, free_list, par);
5608
5609 uint i = hr->hrm_index() + 1;
5610 while (i < last_index) {
5611 HeapRegion* curr_hr = region_at(i);
5612 assert(curr_hr->is_continues_humongous(), "invariant");
5613 curr_hr->clear_humongous();
5614 free_region(curr_hr, free_list, par);
5615 i += 1;
5616 }
5617 }
5618
5619 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5620 const HeapRegionSetCount& humongous_regions_removed) {
5621 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5622 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5623 _old_set.bulk_remove(old_regions_removed);
5624 _humongous_set.bulk_remove(humongous_regions_removed);
5625 }
5626
5627 }
5628
5629 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5630 assert(list != NULL, "list can't be null");
5631 if (!list->is_empty()) {
5632 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5633 _hrm.insert_list_into_free_list(list);
5634 }
5635 }
5636
5637 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5638 _allocator->decrease_used(bytes);
5639 }
5640
5641 class G1ParCleanupCTTask : public AbstractGangTask {
5642 G1SATBCardTableModRefBS* _ct_bs;
5643 G1CollectedHeap* _g1h;
5644 HeapRegion* volatile _su_head;
5645 public:
5646 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5647 G1CollectedHeap* g1h) :
5648 AbstractGangTask("G1 Par Cleanup CT Task"),
5649 _ct_bs(ct_bs), _g1h(g1h) { }
5650
5651 void work(uint worker_id) {
5652 HeapRegion* r;
5653 while (r = _g1h->pop_dirty_cards_region()) {
5654 clear_cards(r);
5655 }
5656 }
5657
5658 void clear_cards(HeapRegion* r) {
5659 // Cards of the survivors should have already been dirtied.
5660 if (!r->is_survivor()) {
5661 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5662 }
5663 }
5664 };
5665
5666 #ifndef PRODUCT
5667 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5668 G1CollectedHeap* _g1h;
5669 G1SATBCardTableModRefBS* _ct_bs;
5670 public:
5671 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5672 : _g1h(g1h), _ct_bs(ct_bs) { }
5673 virtual bool doHeapRegion(HeapRegion* r) {
5674 if (r->is_survivor()) {
5675 _g1h->verify_dirty_region(r);
5676 } else {
5677 _g1h->verify_not_dirty_region(r);
5678 }
5679 return false;
5680 }
5681 };
5682
5683 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5684 // All of the region should be clean.
5685 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5686 MemRegion mr(hr->bottom(), hr->end());
5687 ct_bs->verify_not_dirty_region(mr);
5688 }
5689
5690 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5691 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5692 // dirty allocated blocks as they allocate them. The thread that
5693 // retires each region and replaces it with a new one will do a
5694 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5695 // not dirty that area (one less thing to have to do while holding
5696 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5697 // is dirty.
5698 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5699 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5700 if (hr->is_young()) {
5701 ct_bs->verify_g1_young_region(mr);
5702 } else {
5703 ct_bs->verify_dirty_region(mr);
5704 }
5705 }
5706
5707 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5708 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5709 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5710 verify_dirty_region(hr);
5711 }
5712 }
5713
5714 void G1CollectedHeap::verify_dirty_young_regions() {
5715 verify_dirty_young_list(_young_list->first_region());
5716 }
5717
5718 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5719 HeapWord* tams, HeapWord* end) {
5720 guarantee(tams <= end,
5721 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5722 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5723 if (result < end) {
5724 gclog_or_tty->cr();
5725 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5726 bitmap_name, result);
5727 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5728 bitmap_name, tams, end);
5729 return false;
5730 }
5731 return true;
5732 }
5733
5734 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5735 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5736 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5737
5738 HeapWord* bottom = hr->bottom();
5739 HeapWord* ptams = hr->prev_top_at_mark_start();
5740 HeapWord* ntams = hr->next_top_at_mark_start();
5741 HeapWord* end = hr->end();
5742
5743 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5744
5745 bool res_n = true;
5746 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5747 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5748 // if we happen to be in that state.
5749 if (mark_in_progress() || !_cmThread->in_progress()) {
5750 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5751 }
5752 if (!res_p || !res_n) {
5753 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5754 HR_FORMAT_PARAMS(hr));
5755 gclog_or_tty->print_cr("#### Caller: %s", caller);
5756 return false;
5757 }
5758 return true;
5759 }
5760
5761 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5762 if (!G1VerifyBitmaps) return;
5763
5764 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5765 }
5766
5767 class G1VerifyBitmapClosure : public HeapRegionClosure {
5768 private:
5769 const char* _caller;
5770 G1CollectedHeap* _g1h;
5771 bool _failures;
5772
5773 public:
5774 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5775 _caller(caller), _g1h(g1h), _failures(false) { }
5776
5777 bool failures() { return _failures; }
5778
5779 virtual bool doHeapRegion(HeapRegion* hr) {
5780 if (hr->is_continues_humongous()) return false;
5781
5782 bool result = _g1h->verify_bitmaps(_caller, hr);
5783 if (!result) {
5784 _failures = true;
5785 }
5786 return false;
5787 }
5788 };
5789
5790 void G1CollectedHeap::check_bitmaps(const char* caller) {
5791 if (!G1VerifyBitmaps) return;
5792
5793 G1VerifyBitmapClosure cl(caller, this);
5794 heap_region_iterate(&cl);
5795 guarantee(!cl.failures(), "bitmap verification");
5796 }
5797
5798 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5799 private:
5800 bool _failures;
5801 public:
5802 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5803
5804 virtual bool doHeapRegion(HeapRegion* hr) {
5805 uint i = hr->hrm_index();
5806 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5807 if (hr->is_humongous()) {
5808 if (hr->in_collection_set()) {
5809 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5810 _failures = true;
5811 return true;
5812 }
5813 if (cset_state.is_in_cset()) {
5814 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5815 _failures = true;
5816 return true;
5817 }
5818 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5819 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5820 _failures = true;
5821 return true;
5822 }
5823 } else {
5824 if (cset_state.is_humongous()) {
5825 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5826 _failures = true;
5827 return true;
5828 }
5829 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5830 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5831 hr->in_collection_set(), cset_state.value(), i);
5832 _failures = true;
5833 return true;
5834 }
5835 if (cset_state.is_in_cset()) {
5836 if (hr->is_young() != (cset_state.is_young())) {
5837 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5838 hr->is_young(), cset_state.value(), i);
5839 _failures = true;
5840 return true;
5841 }
5842 if (hr->is_old() != (cset_state.is_old())) {
5843 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5844 hr->is_old(), cset_state.value(), i);
5845 _failures = true;
5846 return true;
5847 }
5848 }
5849 }
5850 return false;
5851 }
5852
5853 bool failures() const { return _failures; }
5854 };
5855
5856 bool G1CollectedHeap::check_cset_fast_test() {
5857 G1CheckCSetFastTableClosure cl;
5858 _hrm.iterate(&cl);
5859 return !cl.failures();
5860 }
5861 #endif // PRODUCT
5862
5863 void G1CollectedHeap::cleanUpCardTable() {
5864 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5865 double start = os::elapsedTime();
5866
5867 {
5868 // Iterate over the dirty cards region list.
5869 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5870
5871 set_par_threads();
5872 workers()->run_task(&cleanup_task);
5873 set_par_threads(0);
5874 #ifndef PRODUCT
5875 if (G1VerifyCTCleanup || VerifyAfterGC) {
5876 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5877 heap_region_iterate(&cleanup_verifier);
5878 }
5879 #endif
5880 }
5881
5882 double elapsed = os::elapsedTime() - start;
5883 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5884 }
5885
5886 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5887 size_t pre_used = 0;
5888 FreeRegionList local_free_list("Local List for CSet Freeing");
5889
5890 double young_time_ms = 0.0;
5891 double non_young_time_ms = 0.0;
5892
5893 // Since the collection set is a superset of the the young list,
5894 // all we need to do to clear the young list is clear its
5895 // head and length, and unlink any young regions in the code below
5896 _young_list->clear();
5897
5898 G1CollectorPolicy* policy = g1_policy();
5899
5900 double start_sec = os::elapsedTime();
5901 bool non_young = true;
5902
5903 HeapRegion* cur = cs_head;
5904 int age_bound = -1;
5905 size_t rs_lengths = 0;
5906
5907 while (cur != NULL) {
5908 assert(!is_on_master_free_list(cur), "sanity");
5909 if (non_young) {
5910 if (cur->is_young()) {
5911 double end_sec = os::elapsedTime();
5912 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5913 non_young_time_ms += elapsed_ms;
5914
5915 start_sec = os::elapsedTime();
5916 non_young = false;
5917 }
5918 } else {
5919 if (!cur->is_young()) {
5920 double end_sec = os::elapsedTime();
5921 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5922 young_time_ms += elapsed_ms;
5923
5924 start_sec = os::elapsedTime();
5925 non_young = true;
5926 }
5927 }
5928
5929 rs_lengths += cur->rem_set()->occupied_locked();
5930
5931 HeapRegion* next = cur->next_in_collection_set();
5932 assert(cur->in_collection_set(), "bad CS");
5933 cur->set_next_in_collection_set(NULL);
5934 clear_in_cset(cur);
5935
5936 if (cur->is_young()) {
5937 int index = cur->young_index_in_cset();
5938 assert(index != -1, "invariant");
5939 assert((uint) index < policy->young_cset_region_length(), "invariant");
5940 size_t words_survived = _surviving_young_words[index];
5941 cur->record_surv_words_in_group(words_survived);
5942
5943 // At this point the we have 'popped' cur from the collection set
5944 // (linked via next_in_collection_set()) but it is still in the
5945 // young list (linked via next_young_region()). Clear the
5946 // _next_young_region field.
5947 cur->set_next_young_region(NULL);
5948 } else {
5949 int index = cur->young_index_in_cset();
5950 assert(index == -1, "invariant");
5951 }
5952
5953 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5954 (!cur->is_young() && cur->young_index_in_cset() == -1),
5955 "invariant" );
5956
5957 if (!cur->evacuation_failed()) {
5958 MemRegion used_mr = cur->used_region();
5959
5960 // And the region is empty.
5961 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5962 pre_used += cur->used();
5963 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5964 } else {
5965 cur->uninstall_surv_rate_group();
5966 if (cur->is_young()) {
5967 cur->set_young_index_in_cset(-1);
5968 }
5969 cur->set_evacuation_failed(false);
5970 // The region is now considered to be old.
5971 cur->set_old();
5972 _old_set.add(cur);
5973 evacuation_info.increment_collectionset_used_after(cur->used());
5974 }
5975 cur = next;
5976 }
5977
5978 evacuation_info.set_regions_freed(local_free_list.length());
5979 policy->record_max_rs_lengths(rs_lengths);
5980 policy->cset_regions_freed();
5981
5982 double end_sec = os::elapsedTime();
5983 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5984
5985 if (non_young) {
5986 non_young_time_ms += elapsed_ms;
5987 } else {
5988 young_time_ms += elapsed_ms;
5989 }
5990
5991 prepend_to_freelist(&local_free_list);
5992 decrement_summary_bytes(pre_used);
5993 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5994 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5995 }
5996
5997 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5998 private:
5999 FreeRegionList* _free_region_list;
6000 HeapRegionSet* _proxy_set;
6001 HeapRegionSetCount _humongous_regions_removed;
6002 size_t _freed_bytes;
6003 public:
6004
6005 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6006 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6007 }
6008
6009 virtual bool doHeapRegion(HeapRegion* r) {
6010 if (!r->is_starts_humongous()) {
6011 return false;
6012 }
6013
6014 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6015
6016 oop obj = (oop)r->bottom();
6017 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6018
6019 // The following checks whether the humongous object is live are sufficient.
6020 // The main additional check (in addition to having a reference from the roots
6021 // or the young gen) is whether the humongous object has a remembered set entry.
6022 //
6023 // A humongous object cannot be live if there is no remembered set for it
6024 // because:
6025 // - there can be no references from within humongous starts regions referencing
6026 // the object because we never allocate other objects into them.
6027 // (I.e. there are no intra-region references that may be missed by the
6028 // remembered set)
6029 // - as soon there is a remembered set entry to the humongous starts region
6030 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6031 // until the end of a concurrent mark.
6032 //
6033 // It is not required to check whether the object has been found dead by marking
6034 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6035 // all objects allocated during that time are considered live.
6036 // SATB marking is even more conservative than the remembered set.
6037 // So if at this point in the collection there is no remembered set entry,
6038 // nobody has a reference to it.
6039 // At the start of collection we flush all refinement logs, and remembered sets
6040 // are completely up-to-date wrt to references to the humongous object.
6041 //
6042 // Other implementation considerations:
6043 // - never consider object arrays at this time because they would pose
6044 // considerable effort for cleaning up the the remembered sets. This is
6045 // required because stale remembered sets might reference locations that
6046 // are currently allocated into.
6047 uint region_idx = r->hrm_index();
6048 if (g1h->humongous_is_live(region_idx) ||
6049 g1h->humongous_region_is_always_live(region_idx)) {
6050
6051 if (G1TraceEagerReclaimHumongousObjects) {
6052 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",
6053 region_idx,
6054 obj->size()*HeapWordSize,
6055 r->bottom(),
6056 r->region_num(),
6057 r->rem_set()->occupied(),
6058 r->rem_set()->strong_code_roots_list_length(),
6059 next_bitmap->isMarked(r->bottom()),
6060 g1h->humongous_is_live(region_idx),
6061 obj->is_objArray()
6062 );
6063 }
6064
6065 return false;
6066 }
6067
6068 guarantee(!obj->is_objArray(),
6069 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6070 r->bottom()));
6071
6072 if (G1TraceEagerReclaimHumongousObjects) {
6073 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",
6074 region_idx,
6075 obj->size()*HeapWordSize,
6076 r->bottom(),
6077 r->region_num(),
6078 r->rem_set()->occupied(),
6079 r->rem_set()->strong_code_roots_list_length(),
6080 next_bitmap->isMarked(r->bottom()),
6081 g1h->humongous_is_live(region_idx),
6082 obj->is_objArray()
6083 );
6084 }
6085 // Need to clear mark bit of the humongous object if already set.
6086 if (next_bitmap->isMarked(r->bottom())) {
6087 next_bitmap->clear(r->bottom());
6088 }
6089 _freed_bytes += r->used();
6090 r->set_containing_set(NULL);
6091 _humongous_regions_removed.increment(1u, r->capacity());
6092 g1h->free_humongous_region(r, _free_region_list, false);
6093
6094 return false;
6095 }
6096
6097 HeapRegionSetCount& humongous_free_count() {
6098 return _humongous_regions_removed;
6099 }
6100
6101 size_t bytes_freed() const {
6102 return _freed_bytes;
6103 }
6104
6105 size_t humongous_reclaimed() const {
6106 return _humongous_regions_removed.length();
6107 }
6108 };
6109
6110 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6111 assert_at_safepoint(true);
6112
6113 if (!G1EagerReclaimHumongousObjects ||
6114 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6115 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6116 return;
6117 }
6118
6119 double start_time = os::elapsedTime();
6120
6121 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6122
6123 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6124 heap_region_iterate(&cl);
6125
6126 HeapRegionSetCount empty_set;
6127 remove_from_old_sets(empty_set, cl.humongous_free_count());
6128
6129 G1HRPrinter* hr_printer = _g1h->hr_printer();
6130 if (hr_printer->is_active()) {
6131 FreeRegionListIterator iter(&local_cleanup_list);
6132 while (iter.more_available()) {
6133 HeapRegion* hr = iter.get_next();
6134 hr_printer->cleanup(hr);
6135 }
6136 }
6137
6138 prepend_to_freelist(&local_cleanup_list);
6139 decrement_summary_bytes(cl.bytes_freed());
6140
6141 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6142 cl.humongous_reclaimed());
6143 }
6144
6145 // This routine is similar to the above but does not record
6146 // any policy statistics or update free lists; we are abandoning
6147 // the current incremental collection set in preparation of a
6148 // full collection. After the full GC we will start to build up
6149 // the incremental collection set again.
6150 // This is only called when we're doing a full collection
6151 // and is immediately followed by the tearing down of the young list.
6152
6153 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6154 HeapRegion* cur = cs_head;
6155
6156 while (cur != NULL) {
6157 HeapRegion* next = cur->next_in_collection_set();
6158 assert(cur->in_collection_set(), "bad CS");
6159 cur->set_next_in_collection_set(NULL);
6160 clear_in_cset(cur);
6161 cur->set_young_index_in_cset(-1);
6162 cur = next;
6163 }
6164 }
6165
6166 void G1CollectedHeap::set_free_regions_coming() {
6167 if (G1ConcRegionFreeingVerbose) {
6168 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6169 "setting free regions coming");
6170 }
6171
6172 assert(!free_regions_coming(), "pre-condition");
6173 _free_regions_coming = true;
6174 }
6175
6176 void G1CollectedHeap::reset_free_regions_coming() {
6177 assert(free_regions_coming(), "pre-condition");
6178
6179 {
6180 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6181 _free_regions_coming = false;
6182 SecondaryFreeList_lock->notify_all();
6183 }
6184
6185 if (G1ConcRegionFreeingVerbose) {
6186 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6187 "reset free regions coming");
6188 }
6189 }
6190
6191 void G1CollectedHeap::wait_while_free_regions_coming() {
6192 // Most of the time we won't have to wait, so let's do a quick test
6193 // first before we take the lock.
6194 if (!free_regions_coming()) {
6195 return;
6196 }
6197
6198 if (G1ConcRegionFreeingVerbose) {
6199 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6200 "waiting for free regions");
6201 }
6202
6203 {
6204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6205 while (free_regions_coming()) {
6206 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6207 }
6208 }
6209
6210 if (G1ConcRegionFreeingVerbose) {
6211 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6212 "done waiting for free regions");
6213 }
6214 }
6215
6216 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6217 assert(heap_lock_held_for_gc(),
6218 "the heap lock should already be held by or for this thread");
6219 _young_list->push_region(hr);
6220 }
6221
6222 class NoYoungRegionsClosure: public HeapRegionClosure {
6223 private:
6224 bool _success;
6225 public:
6226 NoYoungRegionsClosure() : _success(true) { }
6227 bool doHeapRegion(HeapRegion* r) {
6228 if (r->is_young()) {
6229 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6230 r->bottom(), r->end());
6231 _success = false;
6232 }
6233 return false;
6234 }
6235 bool success() { return _success; }
6236 };
6237
6238 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6239 bool ret = _young_list->check_list_empty(check_sample);
6240
6241 if (check_heap) {
6242 NoYoungRegionsClosure closure;
6243 heap_region_iterate(&closure);
6244 ret = ret && closure.success();
6245 }
6246
6247 return ret;
6248 }
6249
6250 class TearDownRegionSetsClosure : public HeapRegionClosure {
6251 private:
6252 HeapRegionSet *_old_set;
6253
6254 public:
6255 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6256
6257 bool doHeapRegion(HeapRegion* r) {
6258 if (r->is_old()) {
6259 _old_set->remove(r);
6260 } else {
6261 // We ignore free regions, we'll empty the free list afterwards.
6262 // We ignore young regions, we'll empty the young list afterwards.
6263 // We ignore humongous regions, we're not tearing down the
6264 // humongous regions set.
6265 assert(r->is_free() || r->is_young() || r->is_humongous(),
6266 "it cannot be another type");
6267 }
6268 return false;
6269 }
6270
6271 ~TearDownRegionSetsClosure() {
6272 assert(_old_set->is_empty(), "post-condition");
6273 }
6274 };
6275
6276 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6277 assert_at_safepoint(true /* should_be_vm_thread */);
6278
6279 if (!free_list_only) {
6280 TearDownRegionSetsClosure cl(&_old_set);
6281 heap_region_iterate(&cl);
6282
6283 // Note that emptying the _young_list is postponed and instead done as
6284 // the first step when rebuilding the regions sets again. The reason for
6285 // this is that during a full GC string deduplication needs to know if
6286 // a collected region was young or old when the full GC was initiated.
6287 }
6288 _hrm.remove_all_free_regions();
6289 }
6290
6291 class RebuildRegionSetsClosure : public HeapRegionClosure {
6292 private:
6293 bool _free_list_only;
6294 HeapRegionSet* _old_set;
6295 HeapRegionManager* _hrm;
6296 size_t _total_used;
6297
6298 public:
6299 RebuildRegionSetsClosure(bool free_list_only,
6300 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6301 _free_list_only(free_list_only),
6302 _old_set(old_set), _hrm(hrm), _total_used(0) {
6303 assert(_hrm->num_free_regions() == 0, "pre-condition");
6304 if (!free_list_only) {
6305 assert(_old_set->is_empty(), "pre-condition");
6306 }
6307 }
6308
6309 bool doHeapRegion(HeapRegion* r) {
6310 if (r->is_continues_humongous()) {
6311 return false;
6312 }
6313
6314 if (r->is_empty()) {
6315 // Add free regions to the free list
6316 r->set_free();
6317 r->set_allocation_context(AllocationContext::system());
6318 _hrm->insert_into_free_list(r);
6319 } else if (!_free_list_only) {
6320 assert(!r->is_young(), "we should not come across young regions");
6321
6322 if (r->is_humongous()) {
6323 // We ignore humongous regions, we left the humongous set unchanged
6324 } else {
6325 // Objects that were compacted would have ended up on regions
6326 // that were previously old or free.
6327 assert(r->is_free() || r->is_old(), "invariant");
6328 // We now consider them old, so register as such.
6329 r->set_old();
6330 _old_set->add(r);
6331 }
6332 _total_used += r->used();
6333 }
6334
6335 return false;
6336 }
6337
6338 size_t total_used() {
6339 return _total_used;
6340 }
6341 };
6342
6343 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6344 assert_at_safepoint(true /* should_be_vm_thread */);
6345
6346 if (!free_list_only) {
6347 _young_list->empty_list();
6348 }
6349
6350 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6351 heap_region_iterate(&cl);
6352
6353 if (!free_list_only) {
6354 _allocator->set_used(cl.total_used());
6355 }
6356 assert(_allocator->used_unlocked() == recalculate_used(),
6357 err_msg("inconsistent _allocator->used_unlocked(), "
6358 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6359 _allocator->used_unlocked(), recalculate_used()));
6360 }
6361
6362 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6363 _refine_cte_cl->set_concurrent(concurrent);
6364 }
6365
6366 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6367 HeapRegion* hr = heap_region_containing(p);
6368 return hr->is_in(p);
6369 }
6370
6371 // Methods for the mutator alloc region
6372
6373 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6374 bool force) {
6375 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6376 assert(!force || g1_policy()->can_expand_young_list(),
6377 "if force is true we should be able to expand the young list");
6378 bool young_list_full = g1_policy()->is_young_list_full();
6379 if (force || !young_list_full) {
6380 HeapRegion* new_alloc_region = new_region(word_size,
6381 false /* is_old */,
6382 false /* do_expand */);
6383 if (new_alloc_region != NULL) {
6384 set_region_short_lived_locked(new_alloc_region);
6385 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6386 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6387 return new_alloc_region;
6388 }
6389 }
6390 return NULL;
6391 }
6392
6393 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6394 size_t allocated_bytes) {
6395 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6396 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6397
6398 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6399 _allocator->increase_used(allocated_bytes);
6400 _hr_printer.retire(alloc_region);
6401 // We update the eden sizes here, when the region is retired,
6402 // instead of when it's allocated, since this is the point that its
6403 // used space has been recored in _summary_bytes_used.
6404 g1mm()->update_eden_size();
6405 }
6406
6407 void G1CollectedHeap::set_par_threads() {
6408 // Don't change the number of workers. Use the value previously set
6409 // in the workgroup.
6410 uint n_workers = workers()->active_workers();
6411 assert(UseDynamicNumberOfGCThreads ||
6412 n_workers == workers()->total_workers(),
6413 "Otherwise should be using the total number of workers");
6414 if (n_workers == 0) {
6415 assert(false, "Should have been set in prior evacuation pause.");
6416 n_workers = ParallelGCThreads;
6417 workers()->set_active_workers(n_workers);
6418 }
6419 set_par_threads(n_workers);
6420 }
6421
6422 // Methods for the GC alloc regions
6423
6424 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6425 uint count,
6426 InCSetState dest) {
6427 assert(FreeList_lock->owned_by_self(), "pre-condition");
6428
6429 if (count < g1_policy()->max_regions(dest)) {
6430 const bool is_survivor = (dest.is_young());
6431 HeapRegion* new_alloc_region = new_region(word_size,
6432 !is_survivor,
6433 true /* do_expand */);
6434 if (new_alloc_region != NULL) {
6435 // We really only need to do this for old regions given that we
6436 // should never scan survivors. But it doesn't hurt to do it
6437 // for survivors too.
6438 new_alloc_region->record_timestamp();
6439 if (is_survivor) {
6440 new_alloc_region->set_survivor();
6441 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6442 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6443 } else {
6444 new_alloc_region->set_old();
6445 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6446 check_bitmaps("Old Region Allocation", new_alloc_region);
6447 }
6448 bool during_im = g1_policy()->during_initial_mark_pause();
6449 new_alloc_region->note_start_of_copying(during_im);
6450 return new_alloc_region;
6451 }
6452 }
6453 return NULL;
6454 }
6455
6456 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6457 size_t allocated_bytes,
6458 InCSetState dest) {
6459 bool during_im = g1_policy()->during_initial_mark_pause();
6460 alloc_region->note_end_of_copying(during_im);
6461 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6462 if (dest.is_young()) {
6463 young_list()->add_survivor_region(alloc_region);
6464 } else {
6465 _old_set.add(alloc_region);
6466 }
6467 _hr_printer.retire(alloc_region);
6468 }
6469
6470 // Heap region set verification
6471
6472 class VerifyRegionListsClosure : public HeapRegionClosure {
6473 private:
6474 HeapRegionSet* _old_set;
6475 HeapRegionSet* _humongous_set;
6476 HeapRegionManager* _hrm;
6477
6478 public:
6479 HeapRegionSetCount _old_count;
6480 HeapRegionSetCount _humongous_count;
6481 HeapRegionSetCount _free_count;
6482
6483 VerifyRegionListsClosure(HeapRegionSet* old_set,
6484 HeapRegionSet* humongous_set,
6485 HeapRegionManager* hrm) :
6486 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6487 _old_count(), _humongous_count(), _free_count(){ }
6488
6489 bool doHeapRegion(HeapRegion* hr) {
6490 if (hr->is_continues_humongous()) {
6491 return false;
6492 }
6493
6494 if (hr->is_young()) {
6495 // TODO
6496 } else if (hr->is_starts_humongous()) {
6497 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6498 _humongous_count.increment(1u, hr->capacity());
6499 } else if (hr->is_empty()) {
6500 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6501 _free_count.increment(1u, hr->capacity());
6502 } else if (hr->is_old()) {
6503 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6504 _old_count.increment(1u, hr->capacity());
6505 } else {
6506 ShouldNotReachHere();
6507 }
6508 return false;
6509 }
6510
6511 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6512 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6513 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6514 old_set->total_capacity_bytes(), _old_count.capacity()));
6515
6516 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6517 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6518 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6519
6520 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()));
6521 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6522 free_list->total_capacity_bytes(), _free_count.capacity()));
6523 }
6524 };
6525
6526 void G1CollectedHeap::verify_region_sets() {
6527 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6528
6529 // First, check the explicit lists.
6530 _hrm.verify();
6531 {
6532 // Given that a concurrent operation might be adding regions to
6533 // the secondary free list we have to take the lock before
6534 // verifying it.
6535 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6536 _secondary_free_list.verify_list();
6537 }
6538
6539 // If a concurrent region freeing operation is in progress it will
6540 // be difficult to correctly attributed any free regions we come
6541 // across to the correct free list given that they might belong to
6542 // one of several (free_list, secondary_free_list, any local lists,
6543 // etc.). So, if that's the case we will skip the rest of the
6544 // verification operation. Alternatively, waiting for the concurrent
6545 // operation to complete will have a non-trivial effect on the GC's
6546 // operation (no concurrent operation will last longer than the
6547 // interval between two calls to verification) and it might hide
6548 // any issues that we would like to catch during testing.
6549 if (free_regions_coming()) {
6550 return;
6551 }
6552
6553 // Make sure we append the secondary_free_list on the free_list so
6554 // that all free regions we will come across can be safely
6555 // attributed to the free_list.
6556 append_secondary_free_list_if_not_empty_with_lock();
6557
6558 // Finally, make sure that the region accounting in the lists is
6559 // consistent with what we see in the heap.
6560
6561 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6562 heap_region_iterate(&cl);
6563 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6564 }
6565
6566 // Optimized nmethod scanning
6567
6568 class RegisterNMethodOopClosure: public OopClosure {
6569 G1CollectedHeap* _g1h;
6570 nmethod* _nm;
6571
6572 template <class T> void do_oop_work(T* p) {
6573 T heap_oop = oopDesc::load_heap_oop(p);
6574 if (!oopDesc::is_null(heap_oop)) {
6575 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6576 HeapRegion* hr = _g1h->heap_region_containing(obj);
6577 assert(!hr->is_continues_humongous(),
6578 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6579 " starting at "HR_FORMAT,
6580 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6581
6582 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6583 hr->add_strong_code_root_locked(_nm);
6584 }
6585 }
6586
6587 public:
6588 RegisterNMethodOopClosure(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 class UnregisterNMethodOopClosure: public OopClosure {
6596 G1CollectedHeap* _g1h;
6597 nmethod* _nm;
6598
6599 template <class T> void do_oop_work(T* p) {
6600 T heap_oop = oopDesc::load_heap_oop(p);
6601 if (!oopDesc::is_null(heap_oop)) {
6602 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6603 HeapRegion* hr = _g1h->heap_region_containing(obj);
6604 assert(!hr->is_continues_humongous(),
6605 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6606 " starting at "HR_FORMAT,
6607 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6608
6609 hr->remove_strong_code_root(_nm);
6610 }
6611 }
6612
6613 public:
6614 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6615 _g1h(g1h), _nm(nm) {}
6616
6617 void do_oop(oop* p) { do_oop_work(p); }
6618 void do_oop(narrowOop* p) { do_oop_work(p); }
6619 };
6620
6621 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6622 CollectedHeap::register_nmethod(nm);
6623
6624 guarantee(nm != NULL, "sanity");
6625 RegisterNMethodOopClosure reg_cl(this, nm);
6626 nm->oops_do(®_cl);
6627 }
6628
6629 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6630 CollectedHeap::unregister_nmethod(nm);
6631
6632 guarantee(nm != NULL, "sanity");
6633 UnregisterNMethodOopClosure reg_cl(this, nm);
6634 nm->oops_do(®_cl, true);
6635 }
6636
6637 void G1CollectedHeap::purge_code_root_memory() {
6638 double purge_start = os::elapsedTime();
6639 G1CodeRootSet::purge();
6640 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6641 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6642 }
6643
6644 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6645 G1CollectedHeap* _g1h;
6646
6647 public:
6648 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6649 _g1h(g1h) {}
6650
6651 void do_code_blob(CodeBlob* cb) {
6652 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6653 if (nm == NULL) {
6654 return;
6655 }
6656
6657 if (ScavengeRootsInCode) {
6658 _g1h->register_nmethod(nm);
6659 }
6660 }
6661 };
6662
6663 void G1CollectedHeap::rebuild_strong_code_roots() {
6664 RebuildStrongCodeRootClosure blob_cl(this);
6665 CodeCache::blobs_do(&blob_cl);
6666 }