1 /*
2 * Copyright (c) 2001, 2014, 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/g1StringDedup.hpp"
52 #include "gc_implementation/g1/g1YCTypes.hpp"
53 #include "gc_implementation/g1/heapRegion.inline.hpp"
54 #include "gc_implementation/g1/heapRegionRemSet.hpp"
55 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
56 #include "gc_implementation/g1/vm_operations_g1.hpp"
57 #include "gc_implementation/shared/gcHeapSummary.hpp"
58 #include "gc_implementation/shared/gcTimer.hpp"
59 #include "gc_implementation/shared/gcTrace.hpp"
60 #include "gc_implementation/shared/gcTraceTime.hpp"
61 #include "gc_implementation/shared/isGCActiveMark.hpp"
62 #include "memory/allocation.hpp"
63 #include "memory/gcLocker.inline.hpp"
64 #include "memory/generationSpec.hpp"
65 #include "memory/iterator.hpp"
66 #include "memory/referenceProcessor.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oop.pcgc.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Notes on implementation of parallelism in different tasks.
93 //
94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
95 // The number of GC workers is passed to heap_region_par_iterate().
96 // It does use run_task() which sets _n_workers in the task.
97 // G1ParTask executes g1_process_roots() ->
98 // SharedHeap::process_roots() which calls eventually to
99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
100 // SequentialSubTasksDone. SharedHeap::process_roots() also
101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
102 //
103
104 // Local to this file.
105
106 class RefineCardTableEntryClosure: public CardTableEntryClosure {
107 bool _concurrent;
108 public:
109 RefineCardTableEntryClosure() : _concurrent(true) { }
110
111 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
112 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
113 // This path is executed by the concurrent refine or mutator threads,
114 // concurrently, and so we do not care if card_ptr contains references
115 // that point into the collection set.
116 assert(!oops_into_cset, "should be");
117
118 if (_concurrent && SuspendibleThreadSet::should_yield()) {
119 // Caller will actually yield.
120 return false;
121 }
122 // Otherwise, we finished successfully; return true.
123 return true;
124 }
125
126 void set_concurrent(bool b) { _concurrent = b; }
127 };
128
129
130 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
131 private:
132 size_t _num_processed;
133
134 public:
135 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
136
137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_processed++;
140 return true;
141 }
142
143 size_t num_processed() const { return _num_processed; }
144 };
145
146 YoungList::YoungList(G1CollectedHeap* g1h) :
147 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
148 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
149 guarantee(check_list_empty(false), "just making sure...");
150 }
151
152 void YoungList::push_region(HeapRegion *hr) {
153 assert(!hr->is_young(), "should not already be young");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_head);
157 _head = hr;
158
159 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
160 ++_length;
161 }
162
163 void YoungList::add_survivor_region(HeapRegion* hr) {
164 assert(hr->is_survivor(), "should be flagged as survivor region");
165 assert(hr->get_next_young_region() == NULL, "cause it should!");
166
167 hr->set_next_young_region(_survivor_head);
168 if (_survivor_head == NULL) {
169 _survivor_tail = hr;
170 }
171 _survivor_head = hr;
172 ++_survivor_length;
173 }
174
175 void YoungList::empty_list(HeapRegion* list) {
176 while (list != NULL) {
177 HeapRegion* next = list->get_next_young_region();
178 list->set_next_young_region(NULL);
179 list->uninstall_surv_rate_group();
180 // This is called before a Full GC and all the non-empty /
181 // non-humongous regions at the end of the Full GC will end up as
182 // old anyway.
183 list->set_old();
184 list = next;
185 }
186 }
187
188 void YoungList::empty_list() {
189 assert(check_list_well_formed(), "young list should be well formed");
190
191 empty_list(_head);
192 _head = NULL;
193 _length = 0;
194
195 empty_list(_survivor_head);
196 _survivor_head = NULL;
197 _survivor_tail = NULL;
198 _survivor_length = 0;
199
200 _last_sampled_rs_lengths = 0;
201
202 assert(check_list_empty(false), "just making sure...");
203 }
204
205 bool YoungList::check_list_well_formed() {
206 bool ret = true;
207
208 uint length = 0;
209 HeapRegion* curr = _head;
210 HeapRegion* last = NULL;
211 while (curr != NULL) {
212 if (!curr->is_young()) {
213 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
214 "incorrectly tagged (y: %d, surv: %d)",
215 curr->bottom(), curr->end(),
216 curr->is_young(), curr->is_survivor());
217 ret = false;
218 }
219 ++length;
220 last = curr;
221 curr = curr->get_next_young_region();
222 }
223 ret = ret && (length == _length);
224
225 if (!ret) {
226 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
227 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
228 length, _length);
229 }
230
231 return ret;
232 }
233
234 bool YoungList::check_list_empty(bool check_sample) {
235 bool ret = true;
236
237 if (_length != 0) {
238 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
239 _length);
240 ret = false;
241 }
242 if (check_sample && _last_sampled_rs_lengths != 0) {
243 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
244 ret = false;
245 }
246 if (_head != NULL) {
247 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
248 ret = false;
249 }
250 if (!ret) {
251 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
252 }
253
254 return ret;
255 }
256
257 void
258 YoungList::rs_length_sampling_init() {
259 _sampled_rs_lengths = 0;
260 _curr = _head;
261 }
262
263 bool
264 YoungList::rs_length_sampling_more() {
265 return _curr != NULL;
266 }
267
268 void
269 YoungList::rs_length_sampling_next() {
270 assert( _curr != NULL, "invariant" );
271 size_t rs_length = _curr->rem_set()->occupied();
272
273 _sampled_rs_lengths += rs_length;
274
275 // The current region may not yet have been added to the
276 // incremental collection set (it gets added when it is
277 // retired as the current allocation region).
278 if (_curr->in_collection_set()) {
279 // Update the collection set policy information for this region
280 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
281 }
282
283 _curr = _curr->get_next_young_region();
284 if (_curr == NULL) {
285 _last_sampled_rs_lengths = _sampled_rs_lengths;
286 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
287 }
288 }
289
290 void
291 YoungList::reset_auxilary_lists() {
292 guarantee( is_empty(), "young list should be empty" );
293 assert(check_list_well_formed(), "young list should be well formed");
294
295 // Add survivor regions to SurvRateGroup.
296 _g1h->g1_policy()->note_start_adding_survivor_regions();
297 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
298
299 int young_index_in_cset = 0;
300 for (HeapRegion* curr = _survivor_head;
301 curr != NULL;
302 curr = curr->get_next_young_region()) {
303 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
304
305 // The region is a non-empty survivor so let's add it to
306 // the incremental collection set for the next evacuation
307 // pause.
308 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
309 young_index_in_cset += 1;
310 }
311 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
312 _g1h->g1_policy()->note_stop_adding_survivor_regions();
313
314 _head = _survivor_head;
315 _length = _survivor_length;
316 if (_survivor_head != NULL) {
317 assert(_survivor_tail != NULL, "cause it shouldn't be");
318 assert(_survivor_length > 0, "invariant");
319 _survivor_tail->set_next_young_region(NULL);
320 }
321
322 // Don't clear the survivor list handles until the start of
323 // the next evacuation pause - we need it in order to re-tag
324 // the survivor regions from this evacuation pause as 'young'
325 // at the start of the next.
326
327 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
328
329 assert(check_list_well_formed(), "young list should be well formed");
330 }
331
332 void YoungList::print() {
333 HeapRegion* lists[] = {_head, _survivor_head};
334 const char* names[] = {"YOUNG", "SURVIVOR"};
335
336 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
337 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
338 HeapRegion *curr = lists[list];
339 if (curr == NULL)
340 gclog_or_tty->print_cr(" empty");
341 while (curr != NULL) {
342 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
343 HR_FORMAT_PARAMS(curr),
344 curr->prev_top_at_mark_start(),
345 curr->next_top_at_mark_start(),
346 curr->age_in_surv_rate_group_cond());
347 curr = curr->get_next_young_region();
348 }
349 }
350
351 gclog_or_tty->cr();
352 }
353
354 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
355 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
356 }
357
358 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
359 // The from card cache is not the memory that is actually committed. So we cannot
360 // take advantage of the zero_filled parameter.
361 reset_from_card_cache(start_idx, num_regions);
362 }
363
364 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
365 {
366 // Claim the right to put the region on the dirty cards region list
367 // by installing a self pointer.
368 HeapRegion* next = hr->get_next_dirty_cards_region();
369 if (next == NULL) {
370 HeapRegion* res = (HeapRegion*)
371 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
372 NULL);
373 if (res == NULL) {
374 HeapRegion* head;
375 do {
376 // Put the region to the dirty cards region list.
377 head = _dirty_cards_region_list;
378 next = (HeapRegion*)
379 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
380 if (next == head) {
381 assert(hr->get_next_dirty_cards_region() == hr,
382 "hr->get_next_dirty_cards_region() != hr");
383 if (next == NULL) {
384 // The last region in the list points to itself.
385 hr->set_next_dirty_cards_region(hr);
386 } else {
387 hr->set_next_dirty_cards_region(next);
388 }
389 }
390 } while (next != head);
391 }
392 }
393 }
394
395 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
396 {
397 HeapRegion* head;
398 HeapRegion* hr;
399 do {
400 head = _dirty_cards_region_list;
401 if (head == NULL) {
402 return NULL;
403 }
404 HeapRegion* new_head = head->get_next_dirty_cards_region();
405 if (head == new_head) {
406 // The last region.
407 new_head = NULL;
408 }
409 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
410 head);
411 } while (hr != head);
412 assert(hr != NULL, "invariant");
413 hr->set_next_dirty_cards_region(NULL);
414 return hr;
415 }
416
417 #ifdef ASSERT
418 // A region is added to the collection set as it is retired
419 // so an address p can point to a region which will be in the
420 // collection set but has not yet been retired. This method
421 // therefore is only accurate during a GC pause after all
422 // regions have been retired. It is used for debugging
423 // to check if an nmethod has references to objects that can
424 // be move during a partial collection. Though it can be
425 // inaccurate, it is sufficient for G1 because the conservative
426 // implementation of is_scavengable() for G1 will indicate that
427 // all nmethods must be scanned during a partial collection.
428 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
429 if (p == NULL) {
430 return false;
431 }
432 return heap_region_containing(p)->in_collection_set();
433 }
434 #endif
435
436 // Returns true if the reference points to an object that
437 // can move in an incremental collection.
438 bool G1CollectedHeap::is_scavengable(const void* p) {
439 HeapRegion* hr = heap_region_containing(p);
440 return !hr->is_humongous();
441 }
442
443 // Private class members.
444
445 G1CollectedHeap* G1CollectedHeap::_g1h;
446
447 // Private methods.
448
449 HeapRegion*
450 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
451 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
452 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
453 if (!_secondary_free_list.is_empty()) {
454 if (G1ConcRegionFreeingVerbose) {
455 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
456 "secondary_free_list has %u entries",
457 _secondary_free_list.length());
458 }
459 // It looks as if there are free regions available on the
460 // secondary_free_list. Let's move them to the free_list and try
461 // again to allocate from it.
462 append_secondary_free_list();
463
464 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
465 "empty we should have moved at least one entry to the free_list");
466 HeapRegion* res = _hrm.allocate_free_region(is_old);
467 if (G1ConcRegionFreeingVerbose) {
468 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
469 "allocated "HR_FORMAT" from secondary_free_list",
470 HR_FORMAT_PARAMS(res));
471 }
472 return res;
473 }
474
475 // Wait here until we get notified either when (a) there are no
476 // more free regions coming or (b) some regions have been moved on
477 // the secondary_free_list.
478 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
479 }
480
481 if (G1ConcRegionFreeingVerbose) {
482 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
483 "could not allocate from secondary_free_list");
484 }
485 return NULL;
486 }
487
488 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
489 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
490 "the only time we use this to allocate a humongous region is "
491 "when we are allocating a single humongous region");
492
493 HeapRegion* res;
494 if (G1StressConcRegionFreeing) {
495 if (!_secondary_free_list.is_empty()) {
496 if (G1ConcRegionFreeingVerbose) {
497 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
498 "forced to look at the secondary_free_list");
499 }
500 res = new_region_try_secondary_free_list(is_old);
501 if (res != NULL) {
502 return res;
503 }
504 }
505 }
506
507 res = _hrm.allocate_free_region(is_old);
508
509 if (res == NULL) {
510 if (G1ConcRegionFreeingVerbose) {
511 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
512 "res == NULL, trying the secondary_free_list");
513 }
514 res = new_region_try_secondary_free_list(is_old);
515 }
516 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
517 // Currently, only attempts to allocate GC alloc regions set
518 // do_expand to true. So, we should only reach here during a
519 // safepoint. If this assumption changes we might have to
520 // reconsider the use of _expand_heap_after_alloc_failure.
521 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
522
523 ergo_verbose1(ErgoHeapSizing,
524 "attempt heap expansion",
525 ergo_format_reason("region allocation request failed")
526 ergo_format_byte("allocation request"),
527 word_size * HeapWordSize);
528 if (expand(word_size * HeapWordSize)) {
529 // Given that expand() succeeded in expanding the heap, and we
530 // always expand the heap by an amount aligned to the heap
531 // region size, the free list should in theory not be empty.
532 // In either case allocate_free_region() will check for NULL.
533 res = _hrm.allocate_free_region(is_old);
534 } else {
535 _expand_heap_after_alloc_failure = false;
536 }
537 }
538 return res;
539 }
540
541 HeapWord*
542 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
543 uint num_regions,
544 size_t word_size,
545 AllocationContext_t context) {
546 assert(first != G1_NO_HRM_INDEX, "pre-condition");
547 assert(is_humongous(word_size), "word_size should be humongous");
548 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
549
550 // Index of last region in the series + 1.
551 uint last = first + num_regions;
552
553 // We need to initialize the region(s) we just discovered. This is
554 // a bit tricky given that it can happen concurrently with
555 // refinement threads refining cards on these regions and
556 // potentially wanting to refine the BOT as they are scanning
557 // those cards (this can happen shortly after a cleanup; see CR
558 // 6991377). So we have to set up the region(s) carefully and in
559 // a specific order.
560
561 // The word size sum of all the regions we will allocate.
562 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
563 assert(word_size <= word_size_sum, "sanity");
564
565 // This will be the "starts humongous" region.
566 HeapRegion* first_hr = region_at(first);
567 // The header of the new object will be placed at the bottom of
568 // the first region.
569 HeapWord* new_obj = first_hr->bottom();
570 // This will be the new end of the first region in the series that
571 // should also match the end of the last region in the series.
572 HeapWord* new_end = new_obj + word_size_sum;
573 // This will be the new top of the first region that will reflect
574 // this allocation.
575 HeapWord* new_top = new_obj + word_size;
576
577 // First, we need to zero the header of the space that we will be
578 // allocating. When we update top further down, some refinement
579 // threads might try to scan the region. By zeroing the header we
580 // ensure that any thread that will try to scan the region will
581 // come across the zero klass word and bail out.
582 //
583 // NOTE: It would not have been correct to have used
584 // CollectedHeap::fill_with_object() and make the space look like
585 // an int array. The thread that is doing the allocation will
586 // later update the object header to a potentially different array
587 // type and, for a very short period of time, the klass and length
588 // fields will be inconsistent. This could cause a refinement
589 // thread to calculate the object size incorrectly.
590 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
591
592 // We will set up the first region as "starts humongous". This
593 // will also update the BOT covering all the regions to reflect
594 // that there is a single object that starts at the bottom of the
595 // first region.
596 first_hr->set_starts_humongous(new_top, new_end);
597 first_hr->set_allocation_context(context);
598 // Then, if there are any, we will set up the "continues
599 // humongous" regions.
600 HeapRegion* hr = NULL;
601 for (uint i = first + 1; i < last; ++i) {
602 hr = region_at(i);
603 hr->set_continues_humongous(first_hr);
604 hr->set_allocation_context(context);
605 }
606 // If we have "continues humongous" regions (hr != NULL), then the
607 // end of the last one should match new_end.
608 assert(hr == NULL || hr->end() == new_end, "sanity");
609
610 // Up to this point no concurrent thread would have been able to
611 // do any scanning on any region in this series. All the top
612 // fields still point to bottom, so the intersection between
613 // [bottom,top] and [card_start,card_end] will be empty. Before we
614 // update the top fields, we'll do a storestore to make sure that
615 // no thread sees the update to top before the zeroing of the
616 // object header and the BOT initialization.
617 OrderAccess::storestore();
618
619 // Now that the BOT and the object header have been initialized,
620 // we can update top of the "starts humongous" region.
621 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
622 "new_top should be in this region");
623 first_hr->set_top(new_top);
624 if (_hr_printer.is_active()) {
625 HeapWord* bottom = first_hr->bottom();
626 HeapWord* end = first_hr->orig_end();
627 if ((first + 1) == last) {
628 // the series has a single humongous region
629 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
630 } else {
631 // the series has more than one humongous regions
632 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
633 }
634 }
635
636 // Now, we will update the top fields of the "continues humongous"
637 // regions. The reason we need to do this is that, otherwise,
638 // these regions would look empty and this will confuse parts of
639 // G1. For example, the code that looks for a consecutive number
640 // of empty regions will consider them empty and try to
641 // re-allocate them. We can extend is_empty() to also include
642 // !is_continues_humongous(), but it is easier to just update the top
643 // fields here. The way we set top for all regions (i.e., top ==
644 // end for all regions but the last one, top == new_top for the
645 // last one) is actually used when we will free up the humongous
646 // region in free_humongous_region().
647 hr = NULL;
648 for (uint i = first + 1; i < last; ++i) {
649 hr = region_at(i);
650 if ((i + 1) == last) {
651 // last continues humongous region
652 assert(hr->bottom() < new_top && new_top <= hr->end(),
653 "new_top should fall on this region");
654 hr->set_top(new_top);
655 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
656 } else {
657 // not last one
658 assert(new_top > hr->end(), "new_top should be above this region");
659 hr->set_top(hr->end());
660 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
661 }
662 }
663 // If we have continues humongous regions (hr != NULL), then the
664 // end of the last one should match new_end and its top should
665 // match new_top.
666 assert(hr == NULL ||
667 (hr->end() == new_end && hr->top() == new_top), "sanity");
668 check_bitmaps("Humongous Region Allocation", first_hr);
669
670 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
671 _allocator->increase_used(first_hr->used());
672 _humongous_set.add(first_hr);
673
674 return new_obj;
675 }
676
677 // If could fit into free regions w/o expansion, try.
678 // Otherwise, if can expand, do so.
679 // Otherwise, if using ex regions might help, try with ex given back.
680 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
681 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
682
683 verify_region_sets_optional();
684
685 uint first = G1_NO_HRM_INDEX;
686 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
687
688 if (obj_regions == 1) {
689 // Only one region to allocate, try to use a fast path by directly allocating
690 // from the free lists. Do not try to expand here, we will potentially do that
691 // later.
692 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
693 if (hr != NULL) {
694 first = hr->hrm_index();
695 }
696 } else {
697 // We can't allocate humongous regions spanning more than one region while
698 // cleanupComplete() is running, since some of the regions we find to be
699 // empty might not yet be added to the free list. It is not straightforward
700 // to know in which list they are on so that we can remove them. We only
701 // need to do this if we need to allocate more than one region to satisfy the
702 // current humongous allocation request. If we are only allocating one region
703 // we use the one-region region allocation code (see above), that already
704 // potentially waits for regions from the secondary free list.
705 wait_while_free_regions_coming();
706 append_secondary_free_list_if_not_empty_with_lock();
707
708 // Policy: Try only empty regions (i.e. already committed first). Maybe we
709 // are lucky enough to find some.
710 first = _hrm.find_contiguous_only_empty(obj_regions);
711 if (first != G1_NO_HRM_INDEX) {
712 _hrm.allocate_free_regions_starting_at(first, obj_regions);
713 }
714 }
715
716 if (first == G1_NO_HRM_INDEX) {
717 // Policy: We could not find enough regions for the humongous object in the
718 // free list. Look through the heap to find a mix of free and uncommitted regions.
719 // If so, try expansion.
720 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
721 if (first != G1_NO_HRM_INDEX) {
722 // We found something. Make sure these regions are committed, i.e. expand
723 // the heap. Alternatively we could do a defragmentation GC.
724 ergo_verbose1(ErgoHeapSizing,
725 "attempt heap expansion",
726 ergo_format_reason("humongous allocation request failed")
727 ergo_format_byte("allocation request"),
728 word_size * HeapWordSize);
729
730 _hrm.expand_at(first, obj_regions);
731 g1_policy()->record_new_heap_size(num_regions());
732
733 #ifdef ASSERT
734 for (uint i = first; i < first + obj_regions; ++i) {
735 HeapRegion* hr = region_at(i);
736 assert(hr->is_free(), "sanity");
737 assert(hr->is_empty(), "sanity");
738 assert(is_on_master_free_list(hr), "sanity");
739 }
740 #endif
741 _hrm.allocate_free_regions_starting_at(first, obj_regions);
742 } else {
743 // Policy: Potentially trigger a defragmentation GC.
744 }
745 }
746
747 HeapWord* result = NULL;
748 if (first != G1_NO_HRM_INDEX) {
749 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
750 word_size, context);
751 assert(result != NULL, "it should always return a valid result");
752
753 // A successful humongous object allocation changes the used space
754 // information of the old generation so we need to recalculate the
755 // sizes and update the jstat counters here.
756 g1mm()->update_sizes();
757 }
758
759 verify_region_sets_optional();
760
761 return result;
762 }
763
764 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
765 assert_heap_not_locked_and_not_at_safepoint();
766 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
767
768 unsigned int dummy_gc_count_before;
769 int dummy_gclocker_retry_count = 0;
770 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
771 }
772
773 HeapWord*
774 G1CollectedHeap::mem_allocate(size_t word_size,
775 bool* gc_overhead_limit_was_exceeded) {
776 assert_heap_not_locked_and_not_at_safepoint();
777
778 // Loop until the allocation is satisfied, or unsatisfied after GC.
779 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
780 unsigned int gc_count_before;
781
782 HeapWord* result = NULL;
783 if (!is_humongous(word_size)) {
784 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
785 } else {
786 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
787 }
788 if (result != NULL) {
789 return result;
790 }
791
792 // Create the garbage collection operation...
793 VM_G1CollectForAllocation op(gc_count_before, word_size);
794 op.set_allocation_context(AllocationContext::current());
795
796 // ...and get the VM thread to execute it.
797 VMThread::execute(&op);
798
799 if (op.prologue_succeeded() && op.pause_succeeded()) {
800 // If the operation was successful we'll return the result even
801 // if it is NULL. If the allocation attempt failed immediately
802 // after a Full GC, it's unlikely we'll be able to allocate now.
803 HeapWord* result = op.result();
804 if (result != NULL && !is_humongous(word_size)) {
805 // Allocations that take place on VM operations do not do any
806 // card dirtying and we have to do it here. We only have to do
807 // this for non-humongous allocations, though.
808 dirty_young_block(result, word_size);
809 }
810 return result;
811 } else {
812 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
813 return NULL;
814 }
815 assert(op.result() == NULL,
816 "the result should be NULL if the VM op did not succeed");
817 }
818
819 // Give a warning if we seem to be looping forever.
820 if ((QueuedAllocationWarningCount > 0) &&
821 (try_count % QueuedAllocationWarningCount == 0)) {
822 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
823 }
824 }
825
826 ShouldNotReachHere();
827 return NULL;
828 }
829
830 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
831 AllocationContext_t context,
832 unsigned int *gc_count_before_ret,
833 int* gclocker_retry_count_ret) {
834 // Make sure you read the note in attempt_allocation_humongous().
835
836 assert_heap_not_locked_and_not_at_safepoint();
837 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
838 "be called for humongous allocation requests");
839
840 // We should only get here after the first-level allocation attempt
841 // (attempt_allocation()) failed to allocate.
842
843 // We will loop until a) we manage to successfully perform the
844 // allocation or b) we successfully schedule a collection which
845 // fails to perform the allocation. b) is the only case when we'll
846 // return NULL.
847 HeapWord* result = NULL;
848 for (int try_count = 1; /* we'll return */; try_count += 1) {
849 bool should_try_gc;
850 unsigned int gc_count_before;
851
852 {
853 MutexLockerEx x(Heap_lock);
854 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
855 false /* bot_updates */);
856 if (result != NULL) {
857 return result;
858 }
859
860 // If we reach here, attempt_allocation_locked() above failed to
861 // allocate a new region. So the mutator alloc region should be NULL.
862 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
863
864 if (GC_locker::is_active_and_needs_gc()) {
865 if (g1_policy()->can_expand_young_list()) {
866 // No need for an ergo verbose message here,
867 // can_expand_young_list() does this when it returns true.
868 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
869 false /* bot_updates */);
870 if (result != NULL) {
871 return result;
872 }
873 }
874 should_try_gc = false;
875 } else {
876 // The GCLocker may not be active but the GCLocker initiated
877 // GC may not yet have been performed (GCLocker::needs_gc()
878 // returns true). In this case we do not try this GC and
879 // wait until the GCLocker initiated GC is performed, and
880 // then retry the allocation.
881 if (GC_locker::needs_gc()) {
882 should_try_gc = false;
883 } else {
884 // Read the GC count while still holding the Heap_lock.
885 gc_count_before = total_collections();
886 should_try_gc = true;
887 }
888 }
889 }
890
891 if (should_try_gc) {
892 bool succeeded;
893 result = do_collection_pause(word_size, gc_count_before, &succeeded,
894 GCCause::_g1_inc_collection_pause);
895 if (result != NULL) {
896 assert(succeeded, "only way to get back a non-NULL result");
897 return result;
898 }
899
900 if (succeeded) {
901 // If we get here we successfully scheduled a collection which
902 // failed to allocate. No point in trying to allocate
903 // further. We'll just return NULL.
904 MutexLockerEx x(Heap_lock);
905 *gc_count_before_ret = total_collections();
906 return NULL;
907 }
908 } else {
909 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
910 MutexLockerEx x(Heap_lock);
911 *gc_count_before_ret = total_collections();
912 return NULL;
913 }
914 // The GCLocker is either active or the GCLocker initiated
915 // GC has not yet been performed. Stall until it is and
916 // then retry the allocation.
917 GC_locker::stall_until_clear();
918 (*gclocker_retry_count_ret) += 1;
919 }
920
921 // We can reach here if we were unsuccessful in scheduling a
922 // collection (because another thread beat us to it) or if we were
923 // stalled due to the GC locker. In either can we should retry the
924 // allocation attempt in case another thread successfully
925 // performed a collection and reclaimed enough space. We do the
926 // first attempt (without holding the Heap_lock) here and the
927 // follow-on attempt will be at the start of the next loop
928 // iteration (after taking the Heap_lock).
929 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
930 false /* bot_updates */);
931 if (result != NULL) {
932 return result;
933 }
934
935 // Give a warning if we seem to be looping forever.
936 if ((QueuedAllocationWarningCount > 0) &&
937 (try_count % QueuedAllocationWarningCount == 0)) {
938 warning("G1CollectedHeap::attempt_allocation_slow() "
939 "retries %d times", try_count);
940 }
941 }
942
943 ShouldNotReachHere();
944 return NULL;
945 }
946
947 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
948 unsigned int * gc_count_before_ret,
949 int* gclocker_retry_count_ret) {
950 // The structure of this method has a lot of similarities to
951 // attempt_allocation_slow(). The reason these two were not merged
952 // into a single one is that such a method would require several "if
953 // allocation is not humongous do this, otherwise do that"
954 // conditional paths which would obscure its flow. In fact, an early
955 // version of this code did use a unified method which was harder to
956 // follow and, as a result, it had subtle bugs that were hard to
957 // track down. So keeping these two methods separate allows each to
958 // be more readable. It will be good to keep these two in sync as
959 // much as possible.
960
961 assert_heap_not_locked_and_not_at_safepoint();
962 assert(is_humongous(word_size), "attempt_allocation_humongous() "
963 "should only be called for humongous allocations");
964
965 // Humongous objects can exhaust the heap quickly, so we should check if we
966 // need to start a marking cycle at each humongous object allocation. We do
967 // the check before we do the actual allocation. The reason for doing it
968 // before the allocation is that we avoid having to keep track of the newly
969 // allocated memory while we do a GC.
970 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
971 word_size)) {
972 collect(GCCause::_g1_humongous_allocation);
973 }
974
975 // We will loop until a) we manage to successfully perform the
976 // allocation or b) we successfully schedule a collection which
977 // fails to perform the allocation. b) is the only case when we'll
978 // return NULL.
979 HeapWord* result = NULL;
980 for (int try_count = 1; /* we'll return */; try_count += 1) {
981 bool should_try_gc;
982 unsigned int gc_count_before;
983
984 {
985 MutexLockerEx x(Heap_lock);
986
987 // Given that humongous objects are not allocated in young
988 // regions, we'll first try to do the allocation without doing a
989 // collection hoping that there's enough space in the heap.
990 result = humongous_obj_allocate(word_size, AllocationContext::current());
991 if (result != NULL) {
992 return result;
993 }
994
995 if (GC_locker::is_active_and_needs_gc()) {
996 should_try_gc = false;
997 } else {
998 // The GCLocker may not be active but the GCLocker initiated
999 // GC may not yet have been performed (GCLocker::needs_gc()
1000 // returns true). In this case we do not try this GC and
1001 // wait until the GCLocker initiated GC is performed, and
1002 // then retry the allocation.
1003 if (GC_locker::needs_gc()) {
1004 should_try_gc = false;
1005 } else {
1006 // Read the GC count while still holding the Heap_lock.
1007 gc_count_before = total_collections();
1008 should_try_gc = true;
1009 }
1010 }
1011 }
1012
1013 if (should_try_gc) {
1014 // If we failed to allocate the humongous object, we should try to
1015 // do a collection pause (if we're allowed) in case it reclaims
1016 // enough space for the allocation to succeed after the pause.
1017
1018 bool succeeded;
1019 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1020 GCCause::_g1_humongous_allocation);
1021 if (result != NULL) {
1022 assert(succeeded, "only way to get back a non-NULL result");
1023 return result;
1024 }
1025
1026 if (succeeded) {
1027 // If we get here we successfully scheduled a collection which
1028 // failed to allocate. No point in trying to allocate
1029 // further. We'll just return NULL.
1030 MutexLockerEx x(Heap_lock);
1031 *gc_count_before_ret = total_collections();
1032 return NULL;
1033 }
1034 } else {
1035 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1036 MutexLockerEx x(Heap_lock);
1037 *gc_count_before_ret = total_collections();
1038 return NULL;
1039 }
1040 // The GCLocker is either active or the GCLocker initiated
1041 // GC has not yet been performed. Stall until it is and
1042 // then retry the allocation.
1043 GC_locker::stall_until_clear();
1044 (*gclocker_retry_count_ret) += 1;
1045 }
1046
1047 // We can reach here if we were unsuccessful in scheduling a
1048 // collection (because another thread beat us to it) or if we were
1049 // stalled due to the GC locker. In either can we should retry the
1050 // allocation attempt in case another thread successfully
1051 // performed a collection and reclaimed enough space. Give a
1052 // warning if we seem to be looping forever.
1053
1054 if ((QueuedAllocationWarningCount > 0) &&
1055 (try_count % QueuedAllocationWarningCount == 0)) {
1056 warning("G1CollectedHeap::attempt_allocation_humongous() "
1057 "retries %d times", try_count);
1058 }
1059 }
1060
1061 ShouldNotReachHere();
1062 return NULL;
1063 }
1064
1065 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1066 AllocationContext_t context,
1067 bool expect_null_mutator_alloc_region) {
1068 assert_at_safepoint(true /* should_be_vm_thread */);
1069 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1070 !expect_null_mutator_alloc_region,
1071 "the current alloc region was unexpectedly found to be non-NULL");
1072
1073 if (!is_humongous(word_size)) {
1074 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1075 false /* bot_updates */);
1076 } else {
1077 HeapWord* result = humongous_obj_allocate(word_size, context);
1078 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1079 g1_policy()->set_initiate_conc_mark_if_possible();
1080 }
1081 return result;
1082 }
1083
1084 ShouldNotReachHere();
1085 }
1086
1087 class PostMCRemSetClearClosure: public HeapRegionClosure {
1088 G1CollectedHeap* _g1h;
1089 ModRefBarrierSet* _mr_bs;
1090 public:
1091 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1092 _g1h(g1h), _mr_bs(mr_bs) {}
1093
1094 bool doHeapRegion(HeapRegion* r) {
1095 HeapRegionRemSet* hrrs = r->rem_set();
1096
1097 if (r->is_continues_humongous()) {
1098 // We'll assert that the strong code root list and RSet is empty
1099 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1100 assert(hrrs->occupied() == 0, "RSet should be empty");
1101 return false;
1102 }
1103
1104 _g1h->reset_gc_time_stamps(r);
1105 hrrs->clear();
1106 // You might think here that we could clear just the cards
1107 // corresponding to the used region. But no: if we leave a dirty card
1108 // in a region we might allocate into, then it would prevent that card
1109 // from being enqueued, and cause it to be missed.
1110 // Re: the performance cost: we shouldn't be doing full GC anyway!
1111 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1112
1113 return false;
1114 }
1115 };
1116
1117 void G1CollectedHeap::clear_rsets_post_compaction() {
1118 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1119 heap_region_iterate(&rs_clear);
1120 }
1121
1122 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1123 G1CollectedHeap* _g1h;
1124 UpdateRSOopClosure _cl;
1125 int _worker_i;
1126 public:
1127 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1128 _cl(g1->g1_rem_set(), worker_i),
1129 _worker_i(worker_i),
1130 _g1h(g1)
1131 { }
1132
1133 bool doHeapRegion(HeapRegion* r) {
1134 if (!r->is_continues_humongous()) {
1135 _cl.set_from(r);
1136 r->oop_iterate(&_cl);
1137 }
1138 return false;
1139 }
1140 };
1141
1142 class ParRebuildRSTask: public AbstractGangTask {
1143 G1CollectedHeap* _g1;
1144 HeapRegionClaimer _hrclaimer;
1145
1146 public:
1147 ParRebuildRSTask(G1CollectedHeap* g1) :
1148 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1149
1150 void work(uint worker_id) {
1151 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1152 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1153 }
1154 };
1155
1156 class PostCompactionPrinterClosure: public HeapRegionClosure {
1157 private:
1158 G1HRPrinter* _hr_printer;
1159 public:
1160 bool doHeapRegion(HeapRegion* hr) {
1161 assert(!hr->is_young(), "not expecting to find young regions");
1162 if (hr->is_free()) {
1163 // We only generate output for non-empty regions.
1164 } else if (hr->is_starts_humongous()) {
1165 if (hr->region_num() == 1) {
1166 // single humongous region
1167 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1168 } else {
1169 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1170 }
1171 } else if (hr->is_continues_humongous()) {
1172 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1173 } else if (hr->is_old()) {
1174 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1175 } else {
1176 ShouldNotReachHere();
1177 }
1178 return false;
1179 }
1180
1181 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1182 : _hr_printer(hr_printer) { }
1183 };
1184
1185 void G1CollectedHeap::print_hrm_post_compaction() {
1186 PostCompactionPrinterClosure cl(hr_printer());
1187 heap_region_iterate(&cl);
1188 }
1189
1190 bool G1CollectedHeap::do_collection(bool explicit_gc,
1191 bool clear_all_soft_refs,
1192 size_t word_size) {
1193 assert_at_safepoint(true /* should_be_vm_thread */);
1194
1195 if (GC_locker::check_active_before_gc()) {
1196 return false;
1197 }
1198
1199 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1200 gc_timer->register_gc_start();
1201
1202 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1203 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1204
1205 SvcGCMarker sgcm(SvcGCMarker::FULL);
1206 ResourceMark rm;
1207
1208 print_heap_before_gc();
1209 trace_heap_before_gc(gc_tracer);
1210
1211 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1212
1213 verify_region_sets_optional();
1214
1215 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1216 collector_policy()->should_clear_all_soft_refs();
1217
1218 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1219
1220 {
1221 IsGCActiveMark x;
1222
1223 // Timing
1224 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1225 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1226
1227 {
1228 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1229 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1230 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1231
1232 double start = os::elapsedTime();
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 double end = os::elapsedTime();
1440 g1_policy()->record_full_collection_end();
1441
1442 if (G1Log::fine()) {
1443 g1_policy()->print_heap_transition();
1444 }
1445
1446 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1447 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1448 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1449 // before any GC notifications are raised.
1450 g1mm()->update_sizes();
1451
1452 gc_epilogue(true);
1453 }
1454
1455 if (G1Log::finer()) {
1456 g1_policy()->print_detailed_heap_transition(true /* full */);
1457 }
1458
1459 print_heap_after_gc();
1460 trace_heap_after_gc(gc_tracer);
1461
1462 post_full_gc_dump(gc_timer);
1463
1464 gc_timer->register_gc_end();
1465 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1466 }
1467
1468 return true;
1469 }
1470
1471 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1472 // do_collection() will return whether it succeeded in performing
1473 // the GC. Currently, there is no facility on the
1474 // do_full_collection() API to notify the caller than the collection
1475 // did not succeed (e.g., because it was locked out by the GC
1476 // locker). So, right now, we'll ignore the return value.
1477 bool dummy = do_collection(true, /* explicit_gc */
1478 clear_all_soft_refs,
1479 0 /* word_size */);
1480 }
1481
1482 // This code is mostly copied from TenuredGeneration.
1483 void
1484 G1CollectedHeap::
1485 resize_if_necessary_after_full_collection(size_t word_size) {
1486 // Include the current allocation, if any, and bytes that will be
1487 // pre-allocated to support collections, as "used".
1488 const size_t used_after_gc = used();
1489 const size_t capacity_after_gc = capacity();
1490 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1491
1492 // This is enforced in arguments.cpp.
1493 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1494 "otherwise the code below doesn't make sense");
1495
1496 // We don't have floating point command-line arguments
1497 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1498 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1499 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1500 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1501
1502 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1503 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1504
1505 // We have to be careful here as these two calculations can overflow
1506 // 32-bit size_t's.
1507 double used_after_gc_d = (double) used_after_gc;
1508 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1509 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1510
1511 // Let's make sure that they are both under the max heap size, which
1512 // by default will make them fit into a size_t.
1513 double desired_capacity_upper_bound = (double) max_heap_size;
1514 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1515 desired_capacity_upper_bound);
1516 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1517 desired_capacity_upper_bound);
1518
1519 // We can now safely turn them into size_t's.
1520 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1521 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1522
1523 // This assert only makes sense here, before we adjust them
1524 // with respect to the min and max heap size.
1525 assert(minimum_desired_capacity <= maximum_desired_capacity,
1526 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1527 "maximum_desired_capacity = "SIZE_FORMAT,
1528 minimum_desired_capacity, maximum_desired_capacity));
1529
1530 // Should not be greater than the heap max size. No need to adjust
1531 // it with respect to the heap min size as it's a lower bound (i.e.,
1532 // we'll try to make the capacity larger than it, not smaller).
1533 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1534 // Should not be less than the heap min size. No need to adjust it
1535 // with respect to the heap max size as it's an upper bound (i.e.,
1536 // we'll try to make the capacity smaller than it, not greater).
1537 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1538
1539 if (capacity_after_gc < minimum_desired_capacity) {
1540 // Don't expand unless it's significant
1541 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1542 ergo_verbose4(ErgoHeapSizing,
1543 "attempt heap expansion",
1544 ergo_format_reason("capacity lower than "
1545 "min desired capacity after Full GC")
1546 ergo_format_byte("capacity")
1547 ergo_format_byte("occupancy")
1548 ergo_format_byte_perc("min desired capacity"),
1549 capacity_after_gc, used_after_gc,
1550 minimum_desired_capacity, (double) MinHeapFreeRatio);
1551 expand(expand_bytes);
1552
1553 // No expansion, now see if we want to shrink
1554 } else if (capacity_after_gc > maximum_desired_capacity) {
1555 // Capacity too large, compute shrinking size
1556 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1557 ergo_verbose4(ErgoHeapSizing,
1558 "attempt heap shrinking",
1559 ergo_format_reason("capacity higher than "
1560 "max desired capacity after Full GC")
1561 ergo_format_byte("capacity")
1562 ergo_format_byte("occupancy")
1563 ergo_format_byte_perc("max desired capacity"),
1564 capacity_after_gc, used_after_gc,
1565 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1566 shrink(shrink_bytes);
1567 }
1568 }
1569
1570
1571 HeapWord*
1572 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1573 AllocationContext_t context,
1574 bool* succeeded) {
1575 assert_at_safepoint(true /* should_be_vm_thread */);
1576
1577 *succeeded = true;
1578 // Let's attempt the allocation first.
1579 HeapWord* result =
1580 attempt_allocation_at_safepoint(word_size,
1581 context,
1582 false /* expect_null_mutator_alloc_region */);
1583 if (result != NULL) {
1584 assert(*succeeded, "sanity");
1585 return result;
1586 }
1587
1588 // In a G1 heap, we're supposed to keep allocation from failing by
1589 // incremental pauses. Therefore, at least for now, we'll favor
1590 // expansion over collection. (This might change in the future if we can
1591 // do something smarter than full collection to satisfy a failed alloc.)
1592 result = expand_and_allocate(word_size, context);
1593 if (result != NULL) {
1594 assert(*succeeded, "sanity");
1595 return result;
1596 }
1597
1598 // Expansion didn't work, we'll try to do a Full GC.
1599 bool gc_succeeded = do_collection(false, /* explicit_gc */
1600 false, /* clear_all_soft_refs */
1601 word_size);
1602 if (!gc_succeeded) {
1603 *succeeded = false;
1604 return NULL;
1605 }
1606
1607 // Retry the allocation
1608 result = attempt_allocation_at_safepoint(word_size,
1609 context,
1610 true /* expect_null_mutator_alloc_region */);
1611 if (result != NULL) {
1612 assert(*succeeded, "sanity");
1613 return result;
1614 }
1615
1616 // Then, try a Full GC that will collect all soft references.
1617 gc_succeeded = do_collection(false, /* explicit_gc */
1618 true, /* clear_all_soft_refs */
1619 word_size);
1620 if (!gc_succeeded) {
1621 *succeeded = false;
1622 return NULL;
1623 }
1624
1625 // Retry the allocation once more
1626 result = attempt_allocation_at_safepoint(word_size,
1627 context,
1628 true /* expect_null_mutator_alloc_region */);
1629 if (result != NULL) {
1630 assert(*succeeded, "sanity");
1631 return result;
1632 }
1633
1634 assert(!collector_policy()->should_clear_all_soft_refs(),
1635 "Flag should have been handled and cleared prior to this point");
1636
1637 // What else? We might try synchronous finalization later. If the total
1638 // space available is large enough for the allocation, then a more
1639 // complete compaction phase than we've tried so far might be
1640 // appropriate.
1641 assert(*succeeded, "sanity");
1642 return NULL;
1643 }
1644
1645 // Attempting to expand the heap sufficiently
1646 // to support an allocation of the given "word_size". If
1647 // successful, perform the allocation and return the address of the
1648 // allocated block, or else "NULL".
1649
1650 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1651 assert_at_safepoint(true /* should_be_vm_thread */);
1652
1653 verify_region_sets_optional();
1654
1655 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1656 ergo_verbose1(ErgoHeapSizing,
1657 "attempt heap expansion",
1658 ergo_format_reason("allocation request failed")
1659 ergo_format_byte("allocation request"),
1660 word_size * HeapWordSize);
1661 if (expand(expand_bytes)) {
1662 _hrm.verify_optional();
1663 verify_region_sets_optional();
1664 return attempt_allocation_at_safepoint(word_size,
1665 context,
1666 false /* expect_null_mutator_alloc_region */);
1667 }
1668 return NULL;
1669 }
1670
1671 bool G1CollectedHeap::expand(size_t expand_bytes) {
1672 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1673 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1674 HeapRegion::GrainBytes);
1675 ergo_verbose2(ErgoHeapSizing,
1676 "expand the heap",
1677 ergo_format_byte("requested expansion amount")
1678 ergo_format_byte("attempted expansion amount"),
1679 expand_bytes, aligned_expand_bytes);
1680
1681 if (is_maximal_no_gc()) {
1682 ergo_verbose0(ErgoHeapSizing,
1683 "did not expand the heap",
1684 ergo_format_reason("heap already fully expanded"));
1685 return false;
1686 }
1687
1688 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1689 assert(regions_to_expand > 0, "Must expand by at least one region");
1690
1691 uint expanded_by = _hrm.expand_by(regions_to_expand);
1692
1693 if (expanded_by > 0) {
1694 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1695 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not expand the heap",
1700 ergo_format_reason("heap expansion operation failed"));
1701 // The expansion of the virtual storage space was unsuccessful.
1702 // Let's see if it was because we ran out of swap.
1703 if (G1ExitOnExpansionFailure &&
1704 _hrm.available() >= regions_to_expand) {
1705 // We had head room...
1706 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1707 }
1708 }
1709 return regions_to_expand > 0;
1710 }
1711
1712 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1713 size_t aligned_shrink_bytes =
1714 ReservedSpace::page_align_size_down(shrink_bytes);
1715 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1716 HeapRegion::GrainBytes);
1717 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1718
1719 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1720 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1721
1722 ergo_verbose3(ErgoHeapSizing,
1723 "shrink the heap",
1724 ergo_format_byte("requested shrinking amount")
1725 ergo_format_byte("aligned shrinking amount")
1726 ergo_format_byte("attempted shrinking amount"),
1727 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1728 if (num_regions_removed > 0) {
1729 g1_policy()->record_new_heap_size(num_regions());
1730 } else {
1731 ergo_verbose0(ErgoHeapSizing,
1732 "did not shrink the heap",
1733 ergo_format_reason("heap shrinking operation failed"));
1734 }
1735 }
1736
1737 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1738 verify_region_sets_optional();
1739
1740 // We should only reach here at the end of a Full GC which means we
1741 // should not not be holding to any GC alloc regions. The method
1742 // below will make sure of that and do any remaining clean up.
1743 _allocator->abandon_gc_alloc_regions();
1744
1745 // Instead of tearing down / rebuilding the free lists here, we
1746 // could instead use the remove_all_pending() method on free_list to
1747 // remove only the ones that we need to remove.
1748 tear_down_region_sets(true /* free_list_only */);
1749 shrink_helper(shrink_bytes);
1750 rebuild_region_sets(true /* free_list_only */);
1751
1752 _hrm.verify_optional();
1753 verify_region_sets_optional();
1754 }
1755
1756 // Public methods.
1757
1758 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1759 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1760 #endif // _MSC_VER
1761
1762
1763 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1764 SharedHeap(policy_),
1765 _g1_policy(policy_),
1766 _dirty_card_queue_set(false),
1767 _into_cset_dirty_card_queue_set(false),
1768 _is_alive_closure_cm(this),
1769 _is_alive_closure_stw(this),
1770 _ref_processor_cm(NULL),
1771 _ref_processor_stw(NULL),
1772 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1773 _bot_shared(NULL),
1774 _evac_failure_scan_stack(NULL),
1775 _mark_in_progress(false),
1776 _cg1r(NULL),
1777 _g1mm(NULL),
1778 _refine_cte_cl(NULL),
1779 _full_collection(false),
1780 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1781 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1782 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1783 _humongous_is_live(),
1784 _has_humongous_reclaim_candidates(false),
1785 _free_regions_coming(false),
1786 _young_list(new YoungList(this)),
1787 _gc_time_stamp(0),
1788 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1789 _old_plab_stats(OldPLABSize, PLABWeight),
1790 _expand_heap_after_alloc_failure(true),
1791 _surviving_young_words(NULL),
1792 _old_marking_cycles_started(0),
1793 _old_marking_cycles_completed(0),
1794 _concurrent_cycle_started(false),
1795 _heap_summary_sent(false),
1796 _in_cset_fast_test(),
1797 _dirty_cards_region_list(NULL),
1798 _worker_cset_start_region(NULL),
1799 _worker_cset_start_region_time_stamp(NULL),
1800 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1801 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1802 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1803 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1804
1805 _g1h = this;
1806 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1807 vm_exit_during_initialization("Failed necessary allocation.");
1808 }
1809
1810 _allocator = G1Allocator::create_allocator(_g1h);
1811 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1812
1813 int n_queues = MAX2((int)ParallelGCThreads, 1);
1814 _task_queues = new RefToScanQueueSet(n_queues);
1815
1816 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1817 assert(n_rem_sets > 0, "Invariant.");
1818
1819 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1820 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1821 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1822
1823 for (int i = 0; i < n_queues; i++) {
1824 RefToScanQueue* q = new RefToScanQueue();
1825 q->initialize();
1826 _task_queues->register_queue(i, q);
1827 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1828 }
1829 clear_cset_start_regions();
1830
1831 // Initialize the G1EvacuationFailureALot counters and flags.
1832 NOT_PRODUCT(reset_evacuation_should_fail();)
1833
1834 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1835 }
1836
1837 jint G1CollectedHeap::initialize() {
1838 CollectedHeap::pre_initialize();
1839 os::enable_vtime();
1840
1841 G1Log::init();
1842
1843 // Necessary to satisfy locking discipline assertions.
1844
1845 MutexLocker x(Heap_lock);
1846
1847 // We have to initialize the printer before committing the heap, as
1848 // it will be used then.
1849 _hr_printer.set_active(G1PrintHeapRegions);
1850
1851 // While there are no constraints in the GC code that HeapWordSize
1852 // be any particular value, there are multiple other areas in the
1853 // system which believe this to be true (e.g. oop->object_size in some
1854 // cases incorrectly returns the size in wordSize units rather than
1855 // HeapWordSize).
1856 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1857
1858 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1859 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1860 size_t heap_alignment = collector_policy()->heap_alignment();
1861
1862 // Ensure that the sizes are properly aligned.
1863 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1864 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1866
1867 _refine_cte_cl = new RefineCardTableEntryClosure();
1868
1869 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1870
1871 // Reserve the maximum.
1872
1873 // When compressed oops are enabled, the preferred heap base
1874 // is calculated by subtracting the requested size from the
1875 // 32Gb boundary and using the result as the base address for
1876 // heap reservation. If the requested size is not aligned to
1877 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1878 // into the ReservedHeapSpace constructor) then the actual
1879 // base of the reserved heap may end up differing from the
1880 // address that was requested (i.e. the preferred heap base).
1881 // If this happens then we could end up using a non-optimal
1882 // compressed oops mode.
1883
1884 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1885 heap_alignment);
1886
1887 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1888
1889 // Create the gen rem set (and barrier set) for the entire reserved region.
1890 _rem_set = collector_policy()->create_rem_set(reserved_region());
1891 set_barrier_set(rem_set()->bs());
1892 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1893 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1894 return JNI_ENOMEM;
1895 }
1896
1897 // Also create a G1 rem set.
1898 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1899
1900 // Carve out the G1 part of the heap.
1901
1902 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1903 G1RegionToSpaceMapper* heap_storage =
1904 G1RegionToSpaceMapper::create_mapper(g1_rs,
1905 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1906 HeapRegion::GrainBytes,
1907 1,
1908 mtJavaHeap);
1909 heap_storage->set_mapping_changed_listener(&_listener);
1910
1911 // Reserve space for the block offset table. We do not support automatic uncommit
1912 // for the card table at this time. BOT only.
1913 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1914 G1RegionToSpaceMapper* bot_storage =
1915 G1RegionToSpaceMapper::create_mapper(bot_rs,
1916 os::vm_page_size(),
1917 HeapRegion::GrainBytes,
1918 G1BlockOffsetSharedArray::N_bytes,
1919 mtGC);
1920
1921 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1922 G1RegionToSpaceMapper* cardtable_storage =
1923 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1924 os::vm_page_size(),
1925 HeapRegion::GrainBytes,
1926 G1BlockOffsetSharedArray::N_bytes,
1927 mtGC);
1928
1929 // Reserve space for the card counts table.
1930 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1931 G1RegionToSpaceMapper* card_counts_storage =
1932 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1933 os::vm_page_size(),
1934 HeapRegion::GrainBytes,
1935 G1BlockOffsetSharedArray::N_bytes,
1936 mtGC);
1937
1938 // Reserve space for prev and next bitmap.
1939 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1940
1941 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1942 G1RegionToSpaceMapper* prev_bitmap_storage =
1943 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1944 os::vm_page_size(),
1945 HeapRegion::GrainBytes,
1946 CMBitMap::mark_distance(),
1947 mtGC);
1948
1949 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1950 G1RegionToSpaceMapper* next_bitmap_storage =
1951 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1952 os::vm_page_size(),
1953 HeapRegion::GrainBytes,
1954 CMBitMap::mark_distance(),
1955 mtGC);
1956
1957 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1958 g1_barrier_set()->initialize(cardtable_storage);
1959 // Do later initialization work for concurrent refinement.
1960 _cg1r->init(card_counts_storage);
1961
1962 // 6843694 - ensure that the maximum region index can fit
1963 // in the remembered set structures.
1964 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1965 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1966
1967 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1968 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1969 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1970 "too many cards per region");
1971
1972 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1973
1974 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1975
1976 _g1h = this;
1977
1978 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1979 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1980
1981 // Create the ConcurrentMark data structure and thread.
1982 // (Must do this late, so that "max_regions" is defined.)
1983 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1984 if (_cm == NULL || !_cm->completed_initialization()) {
1985 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1986 return JNI_ENOMEM;
1987 }
1988 _cmThread = _cm->cmThread();
1989
1990 // Initialize the from_card cache structure of HeapRegionRemSet.
1991 HeapRegionRemSet::init_heap(max_regions());
1992
1993 // Now expand into the initial heap size.
1994 if (!expand(init_byte_size)) {
1995 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1996 return JNI_ENOMEM;
1997 }
1998
1999 // Perform any initialization actions delegated to the policy.
2000 g1_policy()->init();
2001
2002 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2003 SATB_Q_FL_lock,
2004 G1SATBProcessCompletedThreshold,
2005 Shared_SATB_Q_lock);
2006
2007 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2008 DirtyCardQ_CBL_mon,
2009 DirtyCardQ_FL_lock,
2010 concurrent_g1_refine()->yellow_zone(),
2011 concurrent_g1_refine()->red_zone(),
2012 Shared_DirtyCardQ_lock);
2013
2014 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2015 DirtyCardQ_CBL_mon,
2016 DirtyCardQ_FL_lock,
2017 -1, // never trigger processing
2018 -1, // no limit on length
2019 Shared_DirtyCardQ_lock,
2020 &JavaThread::dirty_card_queue_set());
2021
2022 // Initialize the card queue set used to hold cards containing
2023 // references into the collection set.
2024 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2025 DirtyCardQ_CBL_mon,
2026 DirtyCardQ_FL_lock,
2027 -1, // never trigger processing
2028 -1, // no limit on length
2029 Shared_DirtyCardQ_lock,
2030 &JavaThread::dirty_card_queue_set());
2031
2032 // In case we're keeping closure specialization stats, initialize those
2033 // counts and that mechanism.
2034 SpecializationStats::clear();
2035
2036 // Here we allocate the dummy HeapRegion that is required by the
2037 // G1AllocRegion class.
2038 HeapRegion* dummy_region = _hrm.get_dummy_region();
2039
2040 // We'll re-use the same region whether the alloc region will
2041 // require BOT updates or not and, if it doesn't, then a non-young
2042 // region will complain that it cannot support allocations without
2043 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2044 dummy_region->set_eden();
2045 // Make sure it's full.
2046 dummy_region->set_top(dummy_region->end());
2047 G1AllocRegion::setup(this, dummy_region);
2048
2049 _allocator->init_mutator_alloc_region();
2050
2051 // Do create of the monitoring and management support so that
2052 // values in the heap have been properly initialized.
2053 _g1mm = new G1MonitoringSupport(this);
2054
2055 G1StringDedup::initialize();
2056
2057 return JNI_OK;
2058 }
2059
2060 void G1CollectedHeap::stop() {
2061 // Stop all concurrent threads. We do this to make sure these threads
2062 // do not continue to execute and access resources (e.g. gclog_or_tty)
2063 // that are destroyed during shutdown.
2064 _cg1r->stop();
2065 _cmThread->stop();
2066 if (G1StringDedup::is_enabled()) {
2067 G1StringDedup::stop();
2068 }
2069 }
2070
2071 void G1CollectedHeap::clear_humongous_is_live_table() {
2072 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2073 _humongous_is_live.clear();
2074 }
2075
2076 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2077 return HeapRegion::max_region_size();
2078 }
2079
2080 void G1CollectedHeap::ref_processing_init() {
2081 // Reference processing in G1 currently works as follows:
2082 //
2083 // * There are two reference processor instances. One is
2084 // used to record and process discovered references
2085 // during concurrent marking; the other is used to
2086 // record and process references during STW pauses
2087 // (both full and incremental).
2088 // * Both ref processors need to 'span' the entire heap as
2089 // the regions in the collection set may be dotted around.
2090 //
2091 // * For the concurrent marking ref processor:
2092 // * Reference discovery is enabled at initial marking.
2093 // * Reference discovery is disabled and the discovered
2094 // references processed etc during remarking.
2095 // * Reference discovery is MT (see below).
2096 // * Reference discovery requires a barrier (see below).
2097 // * Reference processing may or may not be MT
2098 // (depending on the value of ParallelRefProcEnabled
2099 // and ParallelGCThreads).
2100 // * A full GC disables reference discovery by the CM
2101 // ref processor and abandons any entries on it's
2102 // discovered lists.
2103 //
2104 // * For the STW processor:
2105 // * Non MT discovery is enabled at the start of a full GC.
2106 // * Processing and enqueueing during a full GC is non-MT.
2107 // * During a full GC, references are processed after marking.
2108 //
2109 // * Discovery (may or may not be MT) is enabled at the start
2110 // of an incremental evacuation pause.
2111 // * References are processed near the end of a STW evacuation pause.
2112 // * For both types of GC:
2113 // * Discovery is atomic - i.e. not concurrent.
2114 // * Reference discovery will not need a barrier.
2115
2116 SharedHeap::ref_processing_init();
2117 MemRegion mr = reserved_region();
2118
2119 // Concurrent Mark ref processor
2120 _ref_processor_cm =
2121 new ReferenceProcessor(mr, // span
2122 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2123 // mt processing
2124 (int) ParallelGCThreads,
2125 // degree of mt processing
2126 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2127 // mt discovery
2128 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2129 // degree of mt discovery
2130 false,
2131 // Reference discovery is not atomic
2132 &_is_alive_closure_cm);
2133 // is alive closure
2134 // (for efficiency/performance)
2135
2136 // STW ref processor
2137 _ref_processor_stw =
2138 new ReferenceProcessor(mr, // span
2139 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2140 // mt processing
2141 MAX2((int)ParallelGCThreads, 1),
2142 // degree of mt processing
2143 (ParallelGCThreads > 1),
2144 // mt discovery
2145 MAX2((int)ParallelGCThreads, 1),
2146 // degree of mt discovery
2147 true,
2148 // Reference discovery is atomic
2149 &_is_alive_closure_stw);
2150 // is alive closure
2151 // (for efficiency/performance)
2152 }
2153
2154 size_t G1CollectedHeap::capacity() const {
2155 return _hrm.length() * HeapRegion::GrainBytes;
2156 }
2157
2158 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2159 assert(!hr->is_continues_humongous(), "pre-condition");
2160 hr->reset_gc_time_stamp();
2161 if (hr->is_starts_humongous()) {
2162 uint first_index = hr->hrm_index() + 1;
2163 uint last_index = hr->last_hc_index();
2164 for (uint i = first_index; i < last_index; i += 1) {
2165 HeapRegion* chr = region_at(i);
2166 assert(chr->is_continues_humongous(), "sanity");
2167 chr->reset_gc_time_stamp();
2168 }
2169 }
2170 }
2171
2172 #ifndef PRODUCT
2173 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2174 private:
2175 unsigned _gc_time_stamp;
2176 bool _failures;
2177
2178 public:
2179 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2180 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2181
2182 virtual bool doHeapRegion(HeapRegion* hr) {
2183 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2184 if (_gc_time_stamp != region_gc_time_stamp) {
2185 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2186 "expected %d", HR_FORMAT_PARAMS(hr),
2187 region_gc_time_stamp, _gc_time_stamp);
2188 _failures = true;
2189 }
2190 return false;
2191 }
2192
2193 bool failures() { return _failures; }
2194 };
2195
2196 void G1CollectedHeap::check_gc_time_stamps() {
2197 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2198 heap_region_iterate(&cl);
2199 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2200 }
2201 #endif // PRODUCT
2202
2203 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2204 DirtyCardQueue* into_cset_dcq,
2205 bool concurrent,
2206 uint worker_i) {
2207 // Clean cards in the hot card cache
2208 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2209 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2210
2211 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2212 int n_completed_buffers = 0;
2213 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2214 n_completed_buffers++;
2215 }
2216 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2217 dcqs.clear_n_completed_buffers();
2218 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2219 }
2220
2221
2222 // Computes the sum of the storage used by the various regions.
2223 size_t G1CollectedHeap::used() const {
2224 return _allocator->used();
2225 }
2226
2227 size_t G1CollectedHeap::used_unlocked() const {
2228 return _allocator->used_unlocked();
2229 }
2230
2231 class SumUsedClosure: public HeapRegionClosure {
2232 size_t _used;
2233 public:
2234 SumUsedClosure() : _used(0) {}
2235 bool doHeapRegion(HeapRegion* r) {
2236 if (!r->is_continues_humongous()) {
2237 _used += r->used();
2238 }
2239 return false;
2240 }
2241 size_t result() { return _used; }
2242 };
2243
2244 size_t G1CollectedHeap::recalculate_used() const {
2245 double recalculate_used_start = os::elapsedTime();
2246
2247 SumUsedClosure blk;
2248 heap_region_iterate(&blk);
2249
2250 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2251 return blk.result();
2252 }
2253
2254 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2255 switch (cause) {
2256 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2257 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2258 case GCCause::_g1_humongous_allocation: return true;
2259 case GCCause::_update_allocation_context_stats_inc: return true;
2260 case GCCause::_wb_conc_mark: return true;
2261 default: return false;
2262 }
2263 }
2264
2265 #ifndef PRODUCT
2266 void G1CollectedHeap::allocate_dummy_regions() {
2267 // Let's fill up most of the region
2268 size_t word_size = HeapRegion::GrainWords - 1024;
2269 // And as a result the region we'll allocate will be humongous.
2270 guarantee(is_humongous(word_size), "sanity");
2271
2272 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2273 // Let's use the existing mechanism for the allocation
2274 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2275 AllocationContext::system());
2276 if (dummy_obj != NULL) {
2277 MemRegion mr(dummy_obj, word_size);
2278 CollectedHeap::fill_with_object(mr);
2279 } else {
2280 // If we can't allocate once, we probably cannot allocate
2281 // again. Let's get out of the loop.
2282 break;
2283 }
2284 }
2285 }
2286 #endif // !PRODUCT
2287
2288 void G1CollectedHeap::increment_old_marking_cycles_started() {
2289 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2290 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2291 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2292 _old_marking_cycles_started, _old_marking_cycles_completed));
2293
2294 _old_marking_cycles_started++;
2295 }
2296
2297 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2298 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2299
2300 // We assume that if concurrent == true, then the caller is a
2301 // concurrent thread that was joined the Suspendible Thread
2302 // Set. If there's ever a cheap way to check this, we should add an
2303 // assert here.
2304
2305 // Given that this method is called at the end of a Full GC or of a
2306 // concurrent cycle, and those can be nested (i.e., a Full GC can
2307 // interrupt a concurrent cycle), the number of full collections
2308 // completed should be either one (in the case where there was no
2309 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2310 // behind the number of full collections started.
2311
2312 // This is the case for the inner caller, i.e. a Full GC.
2313 assert(concurrent ||
2314 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2315 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2316 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2317 "is inconsistent with _old_marking_cycles_completed = %u",
2318 _old_marking_cycles_started, _old_marking_cycles_completed));
2319
2320 // This is the case for the outer caller, i.e. the concurrent cycle.
2321 assert(!concurrent ||
2322 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2323 err_msg("for outer caller (concurrent cycle): "
2324 "_old_marking_cycles_started = %u "
2325 "is inconsistent with _old_marking_cycles_completed = %u",
2326 _old_marking_cycles_started, _old_marking_cycles_completed));
2327
2328 _old_marking_cycles_completed += 1;
2329
2330 // We need to clear the "in_progress" flag in the CM thread before
2331 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2332 // is set) so that if a waiter requests another System.gc() it doesn't
2333 // incorrectly see that a marking cycle is still in progress.
2334 if (concurrent) {
2335 _cmThread->clear_in_progress();
2336 }
2337
2338 // This notify_all() will ensure that a thread that called
2339 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2340 // and it's waiting for a full GC to finish will be woken up. It is
2341 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2342 FullGCCount_lock->notify_all();
2343 }
2344
2345 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2346 _concurrent_cycle_started = true;
2347 _gc_timer_cm->register_gc_start(start_time);
2348
2349 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2350 trace_heap_before_gc(_gc_tracer_cm);
2351 }
2352
2353 void G1CollectedHeap::register_concurrent_cycle_end() {
2354 if (_concurrent_cycle_started) {
2355 if (_cm->has_aborted()) {
2356 _gc_tracer_cm->report_concurrent_mode_failure();
2357 }
2358
2359 _gc_timer_cm->register_gc_end();
2360 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2361
2362 // Clear state variables to prepare for the next concurrent cycle.
2363 _concurrent_cycle_started = false;
2364 _heap_summary_sent = false;
2365 }
2366 }
2367
2368 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2369 if (_concurrent_cycle_started) {
2370 // This function can be called when:
2371 // the cleanup pause is run
2372 // the concurrent cycle is aborted before the cleanup pause.
2373 // the concurrent cycle is aborted after the cleanup pause,
2374 // but before the concurrent cycle end has been registered.
2375 // Make sure that we only send the heap information once.
2376 if (!_heap_summary_sent) {
2377 trace_heap_after_gc(_gc_tracer_cm);
2378 _heap_summary_sent = true;
2379 }
2380 }
2381 }
2382
2383 G1YCType G1CollectedHeap::yc_type() {
2384 bool is_young = g1_policy()->gcs_are_young();
2385 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2386 bool is_during_mark = mark_in_progress();
2387
2388 if (is_initial_mark) {
2389 return InitialMark;
2390 } else if (is_during_mark) {
2391 return DuringMark;
2392 } else if (is_young) {
2393 return Normal;
2394 } else {
2395 return Mixed;
2396 }
2397 }
2398
2399 void G1CollectedHeap::collect(GCCause::Cause cause) {
2400 assert_heap_not_locked();
2401
2402 unsigned int gc_count_before;
2403 unsigned int old_marking_count_before;
2404 unsigned int full_gc_count_before;
2405 bool retry_gc;
2406
2407 do {
2408 retry_gc = false;
2409
2410 {
2411 MutexLocker ml(Heap_lock);
2412
2413 // Read the GC count while holding the Heap_lock
2414 gc_count_before = total_collections();
2415 full_gc_count_before = total_full_collections();
2416 old_marking_count_before = _old_marking_cycles_started;
2417 }
2418
2419 if (should_do_concurrent_full_gc(cause)) {
2420 // Schedule an initial-mark evacuation pause that will start a
2421 // concurrent cycle. We're setting word_size to 0 which means that
2422 // we are not requesting a post-GC allocation.
2423 VM_G1IncCollectionPause op(gc_count_before,
2424 0, /* word_size */
2425 true, /* should_initiate_conc_mark */
2426 g1_policy()->max_pause_time_ms(),
2427 cause);
2428 op.set_allocation_context(AllocationContext::current());
2429
2430 VMThread::execute(&op);
2431 if (!op.pause_succeeded()) {
2432 if (old_marking_count_before == _old_marking_cycles_started) {
2433 retry_gc = op.should_retry_gc();
2434 } else {
2435 // A Full GC happened while we were trying to schedule the
2436 // initial-mark GC. No point in starting a new cycle given
2437 // that the whole heap was collected anyway.
2438 }
2439
2440 if (retry_gc) {
2441 if (GC_locker::is_active_and_needs_gc()) {
2442 GC_locker::stall_until_clear();
2443 }
2444 }
2445 }
2446 } else {
2447 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2448 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2449
2450 // Schedule a standard evacuation pause. We're setting word_size
2451 // to 0 which means that we are not requesting a post-GC allocation.
2452 VM_G1IncCollectionPause op(gc_count_before,
2453 0, /* word_size */
2454 false, /* should_initiate_conc_mark */
2455 g1_policy()->max_pause_time_ms(),
2456 cause);
2457 VMThread::execute(&op);
2458 } else {
2459 // Schedule a Full GC.
2460 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2461 VMThread::execute(&op);
2462 }
2463 }
2464 } while (retry_gc);
2465 }
2466
2467 bool G1CollectedHeap::is_in(const void* p) const {
2468 if (_hrm.reserved().contains(p)) {
2469 // Given that we know that p is in the reserved space,
2470 // heap_region_containing_raw() should successfully
2471 // return the containing region.
2472 HeapRegion* hr = heap_region_containing_raw(p);
2473 return hr->is_in(p);
2474 } else {
2475 return false;
2476 }
2477 }
2478
2479 #ifdef ASSERT
2480 bool G1CollectedHeap::is_in_exact(const void* p) const {
2481 bool contains = reserved_region().contains(p);
2482 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2483 if (contains && available) {
2484 return true;
2485 } else {
2486 return false;
2487 }
2488 }
2489 #endif
2490
2491 // Iteration functions.
2492
2493 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2494
2495 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2496 ExtendedOopClosure* _cl;
2497 public:
2498 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2499 bool doHeapRegion(HeapRegion* r) {
2500 if (!r->is_continues_humongous()) {
2501 r->oop_iterate(_cl);
2502 }
2503 return false;
2504 }
2505 };
2506
2507 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2508 IterateOopClosureRegionClosure blk(cl);
2509 heap_region_iterate(&blk);
2510 }
2511
2512 // Iterates an ObjectClosure over all objects within a HeapRegion.
2513
2514 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2515 ObjectClosure* _cl;
2516 public:
2517 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2518 bool doHeapRegion(HeapRegion* r) {
2519 if (!r->is_continues_humongous()) {
2520 r->object_iterate(_cl);
2521 }
2522 return false;
2523 }
2524 };
2525
2526 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2527 IterateObjectClosureRegionClosure blk(cl);
2528 heap_region_iterate(&blk);
2529 }
2530
2531 // Calls a SpaceClosure on a HeapRegion.
2532
2533 class SpaceClosureRegionClosure: public HeapRegionClosure {
2534 SpaceClosure* _cl;
2535 public:
2536 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2537 bool doHeapRegion(HeapRegion* r) {
2538 _cl->do_space(r);
2539 return false;
2540 }
2541 };
2542
2543 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2544 SpaceClosureRegionClosure blk(cl);
2545 heap_region_iterate(&blk);
2546 }
2547
2548 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2549 _hrm.iterate(cl);
2550 }
2551
2552 void
2553 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2554 uint worker_id,
2555 HeapRegionClaimer *hrclaimer,
2556 bool concurrent) const {
2557 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2558 }
2559
2560 // Clear the cached CSet starting regions and (more importantly)
2561 // the time stamps. Called when we reset the GC time stamp.
2562 void G1CollectedHeap::clear_cset_start_regions() {
2563 assert(_worker_cset_start_region != NULL, "sanity");
2564 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2565
2566 int n_queues = MAX2((int)ParallelGCThreads, 1);
2567 for (int i = 0; i < n_queues; i++) {
2568 _worker_cset_start_region[i] = NULL;
2569 _worker_cset_start_region_time_stamp[i] = 0;
2570 }
2571 }
2572
2573 // Given the id of a worker, obtain or calculate a suitable
2574 // starting region for iterating over the current collection set.
2575 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2576 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2577
2578 HeapRegion* result = NULL;
2579 unsigned gc_time_stamp = get_gc_time_stamp();
2580
2581 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2582 // Cached starting region for current worker was set
2583 // during the current pause - so it's valid.
2584 // Note: the cached starting heap region may be NULL
2585 // (when the collection set is empty).
2586 result = _worker_cset_start_region[worker_i];
2587 assert(result == NULL || result->in_collection_set(), "sanity");
2588 return result;
2589 }
2590
2591 // The cached entry was not valid so let's calculate
2592 // a suitable starting heap region for this worker.
2593
2594 // We want the parallel threads to start their collection
2595 // set iteration at different collection set regions to
2596 // avoid contention.
2597 // If we have:
2598 // n collection set regions
2599 // p threads
2600 // Then thread t will start at region floor ((t * n) / p)
2601
2602 result = g1_policy()->collection_set();
2603 uint cs_size = g1_policy()->cset_region_length();
2604 uint active_workers = workers()->active_workers();
2605 assert(UseDynamicNumberOfGCThreads ||
2606 active_workers == workers()->total_workers(),
2607 "Unless dynamic should use total workers");
2608
2609 uint end_ind = (cs_size * worker_i) / active_workers;
2610 uint start_ind = 0;
2611
2612 if (worker_i > 0 &&
2613 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2614 // Previous workers starting region is valid
2615 // so let's iterate from there
2616 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2617 result = _worker_cset_start_region[worker_i - 1];
2618 }
2619
2620 for (uint i = start_ind; i < end_ind; i++) {
2621 result = result->next_in_collection_set();
2622 }
2623
2624 // Note: the calculated starting heap region may be NULL
2625 // (when the collection set is empty).
2626 assert(result == NULL || result->in_collection_set(), "sanity");
2627 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2628 "should be updated only once per pause");
2629 _worker_cset_start_region[worker_i] = result;
2630 OrderAccess::storestore();
2631 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2632 return result;
2633 }
2634
2635 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2636 HeapRegion* r = g1_policy()->collection_set();
2637 while (r != NULL) {
2638 HeapRegion* next = r->next_in_collection_set();
2639 if (cl->doHeapRegion(r)) {
2640 cl->incomplete();
2641 return;
2642 }
2643 r = next;
2644 }
2645 }
2646
2647 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2648 HeapRegionClosure *cl) {
2649 if (r == NULL) {
2650 // The CSet is empty so there's nothing to do.
2651 return;
2652 }
2653
2654 assert(r->in_collection_set(),
2655 "Start region must be a member of the collection set.");
2656 HeapRegion* cur = r;
2657 while (cur != NULL) {
2658 HeapRegion* next = cur->next_in_collection_set();
2659 if (cl->doHeapRegion(cur) && false) {
2660 cl->incomplete();
2661 return;
2662 }
2663 cur = next;
2664 }
2665 cur = g1_policy()->collection_set();
2666 while (cur != r) {
2667 HeapRegion* next = cur->next_in_collection_set();
2668 if (cl->doHeapRegion(cur) && false) {
2669 cl->incomplete();
2670 return;
2671 }
2672 cur = next;
2673 }
2674 }
2675
2676 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2677 HeapRegion* result = _hrm.next_region_in_heap(from);
2678 while (result != NULL && result->is_humongous()) {
2679 result = _hrm.next_region_in_heap(result);
2680 }
2681 return result;
2682 }
2683
2684 Space* G1CollectedHeap::space_containing(const void* addr) const {
2685 return heap_region_containing(addr);
2686 }
2687
2688 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2689 Space* sp = space_containing(addr);
2690 return sp->block_start(addr);
2691 }
2692
2693 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2694 Space* sp = space_containing(addr);
2695 return sp->block_size(addr);
2696 }
2697
2698 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2699 Space* sp = space_containing(addr);
2700 return sp->block_is_obj(addr);
2701 }
2702
2703 bool G1CollectedHeap::supports_tlab_allocation() const {
2704 return true;
2705 }
2706
2707 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2708 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2709 }
2710
2711 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2712 return young_list()->eden_used_bytes();
2713 }
2714
2715 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2716 // must be smaller than the humongous object limit.
2717 size_t G1CollectedHeap::max_tlab_size() const {
2718 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2719 }
2720
2721 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2722 // Return the remaining space in the cur alloc region, but not less than
2723 // the min TLAB size.
2724
2725 // Also, this value can be at most the humongous object threshold,
2726 // since we can't allow tlabs to grow big enough to accommodate
2727 // humongous objects.
2728
2729 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2730 size_t max_tlab = max_tlab_size() * wordSize;
2731 if (hr == NULL) {
2732 return max_tlab;
2733 } else {
2734 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2735 }
2736 }
2737
2738 size_t G1CollectedHeap::max_capacity() const {
2739 return _hrm.reserved().byte_size();
2740 }
2741
2742 jlong G1CollectedHeap::millis_since_last_gc() {
2743 // assert(false, "NYI");
2744 return 0;
2745 }
2746
2747 void G1CollectedHeap::prepare_for_verify() {
2748 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2749 ensure_parsability(false);
2750 }
2751 g1_rem_set()->prepare_for_verify();
2752 }
2753
2754 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2755 VerifyOption vo) {
2756 switch (vo) {
2757 case VerifyOption_G1UsePrevMarking:
2758 return hr->obj_allocated_since_prev_marking(obj);
2759 case VerifyOption_G1UseNextMarking:
2760 return hr->obj_allocated_since_next_marking(obj);
2761 case VerifyOption_G1UseMarkWord:
2762 return false;
2763 default:
2764 ShouldNotReachHere();
2765 }
2766 return false; // keep some compilers happy
2767 }
2768
2769 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2770 switch (vo) {
2771 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2772 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2773 case VerifyOption_G1UseMarkWord: return NULL;
2774 default: ShouldNotReachHere();
2775 }
2776 return NULL; // keep some compilers happy
2777 }
2778
2779 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2780 switch (vo) {
2781 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2782 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2783 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2784 default: ShouldNotReachHere();
2785 }
2786 return false; // keep some compilers happy
2787 }
2788
2789 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2790 switch (vo) {
2791 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2792 case VerifyOption_G1UseNextMarking: return "NTAMS";
2793 case VerifyOption_G1UseMarkWord: return "NONE";
2794 default: ShouldNotReachHere();
2795 }
2796 return NULL; // keep some compilers happy
2797 }
2798
2799 class VerifyRootsClosure: public OopClosure {
2800 private:
2801 G1CollectedHeap* _g1h;
2802 VerifyOption _vo;
2803 bool _failures;
2804 public:
2805 // _vo == UsePrevMarking -> use "prev" marking information,
2806 // _vo == UseNextMarking -> use "next" marking information,
2807 // _vo == UseMarkWord -> use mark word from object header.
2808 VerifyRootsClosure(VerifyOption vo) :
2809 _g1h(G1CollectedHeap::heap()),
2810 _vo(vo),
2811 _failures(false) { }
2812
2813 bool failures() { return _failures; }
2814
2815 template <class T> void do_oop_nv(T* p) {
2816 T heap_oop = oopDesc::load_heap_oop(p);
2817 if (!oopDesc::is_null(heap_oop)) {
2818 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2819 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2820 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2821 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2822 if (_vo == VerifyOption_G1UseMarkWord) {
2823 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2824 }
2825 obj->print_on(gclog_or_tty);
2826 _failures = true;
2827 }
2828 }
2829 }
2830
2831 void do_oop(oop* p) { do_oop_nv(p); }
2832 void do_oop(narrowOop* p) { do_oop_nv(p); }
2833 };
2834
2835 class G1VerifyCodeRootOopClosure: public OopClosure {
2836 G1CollectedHeap* _g1h;
2837 OopClosure* _root_cl;
2838 nmethod* _nm;
2839 VerifyOption _vo;
2840 bool _failures;
2841
2842 template <class T> void do_oop_work(T* p) {
2843 // First verify that this root is live
2844 _root_cl->do_oop(p);
2845
2846 if (!G1VerifyHeapRegionCodeRoots) {
2847 // We're not verifying the code roots attached to heap region.
2848 return;
2849 }
2850
2851 // Don't check the code roots during marking verification in a full GC
2852 if (_vo == VerifyOption_G1UseMarkWord) {
2853 return;
2854 }
2855
2856 // Now verify that the current nmethod (which contains p) is
2857 // in the code root list of the heap region containing the
2858 // object referenced by p.
2859
2860 T heap_oop = oopDesc::load_heap_oop(p);
2861 if (!oopDesc::is_null(heap_oop)) {
2862 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2863
2864 // Now fetch the region containing the object
2865 HeapRegion* hr = _g1h->heap_region_containing(obj);
2866 HeapRegionRemSet* hrrs = hr->rem_set();
2867 // Verify that the strong code root list for this region
2868 // contains the nmethod
2869 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2870 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2871 "from nmethod "PTR_FORMAT" not in strong "
2872 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2873 p, _nm, hr->bottom(), hr->end());
2874 _failures = true;
2875 }
2876 }
2877 }
2878
2879 public:
2880 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2881 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2882
2883 void do_oop(oop* p) { do_oop_work(p); }
2884 void do_oop(narrowOop* p) { do_oop_work(p); }
2885
2886 void set_nmethod(nmethod* nm) { _nm = nm; }
2887 bool failures() { return _failures; }
2888 };
2889
2890 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2891 G1VerifyCodeRootOopClosure* _oop_cl;
2892
2893 public:
2894 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2895 _oop_cl(oop_cl) {}
2896
2897 void do_code_blob(CodeBlob* cb) {
2898 nmethod* nm = cb->as_nmethod_or_null();
2899 if (nm != NULL) {
2900 _oop_cl->set_nmethod(nm);
2901 nm->oops_do(_oop_cl);
2902 }
2903 }
2904 };
2905
2906 class YoungRefCounterClosure : public OopClosure {
2907 G1CollectedHeap* _g1h;
2908 int _count;
2909 public:
2910 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2911 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2912 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2913
2914 int count() { return _count; }
2915 void reset_count() { _count = 0; };
2916 };
2917
2918 class VerifyKlassClosure: public KlassClosure {
2919 YoungRefCounterClosure _young_ref_counter_closure;
2920 OopClosure *_oop_closure;
2921 public:
2922 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2923 void do_klass(Klass* k) {
2924 k->oops_do(_oop_closure);
2925
2926 _young_ref_counter_closure.reset_count();
2927 k->oops_do(&_young_ref_counter_closure);
2928 if (_young_ref_counter_closure.count() > 0) {
2929 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2930 }
2931 }
2932 };
2933
2934 class VerifyLivenessOopClosure: public OopClosure {
2935 G1CollectedHeap* _g1h;
2936 VerifyOption _vo;
2937 public:
2938 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2939 _g1h(g1h), _vo(vo)
2940 { }
2941 void do_oop(narrowOop *p) { do_oop_work(p); }
2942 void do_oop( oop *p) { do_oop_work(p); }
2943
2944 template <class T> void do_oop_work(T *p) {
2945 oop obj = oopDesc::load_decode_heap_oop(p);
2946 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2947 "Dead object referenced by a not dead object");
2948 }
2949 };
2950
2951 class VerifyObjsInRegionClosure: public ObjectClosure {
2952 private:
2953 G1CollectedHeap* _g1h;
2954 size_t _live_bytes;
2955 HeapRegion *_hr;
2956 VerifyOption _vo;
2957 public:
2958 // _vo == UsePrevMarking -> use "prev" marking information,
2959 // _vo == UseNextMarking -> use "next" marking information,
2960 // _vo == UseMarkWord -> use mark word from object header.
2961 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2962 : _live_bytes(0), _hr(hr), _vo(vo) {
2963 _g1h = G1CollectedHeap::heap();
2964 }
2965 void do_object(oop o) {
2966 VerifyLivenessOopClosure isLive(_g1h, _vo);
2967 assert(o != NULL, "Huh?");
2968 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2969 // If the object is alive according to the mark word,
2970 // then verify that the marking information agrees.
2971 // Note we can't verify the contra-positive of the
2972 // above: if the object is dead (according to the mark
2973 // word), it may not be marked, or may have been marked
2974 // but has since became dead, or may have been allocated
2975 // since the last marking.
2976 if (_vo == VerifyOption_G1UseMarkWord) {
2977 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2978 }
2979
2980 o->oop_iterate_no_header(&isLive);
2981 if (!_hr->obj_allocated_since_prev_marking(o)) {
2982 size_t obj_size = o->size(); // Make sure we don't overflow
2983 _live_bytes += (obj_size * HeapWordSize);
2984 }
2985 }
2986 }
2987 size_t live_bytes() { return _live_bytes; }
2988 };
2989
2990 class PrintObjsInRegionClosure : public ObjectClosure {
2991 HeapRegion *_hr;
2992 G1CollectedHeap *_g1;
2993 public:
2994 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2995 _g1 = G1CollectedHeap::heap();
2996 };
2997
2998 void do_object(oop o) {
2999 if (o != NULL) {
3000 HeapWord *start = (HeapWord *) o;
3001 size_t word_sz = o->size();
3002 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3003 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3004 (void*) o, word_sz,
3005 _g1->isMarkedPrev(o),
3006 _g1->isMarkedNext(o),
3007 _hr->obj_allocated_since_prev_marking(o));
3008 HeapWord *end = start + word_sz;
3009 HeapWord *cur;
3010 int *val;
3011 for (cur = start; cur < end; cur++) {
3012 val = (int *) cur;
3013 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3014 }
3015 }
3016 }
3017 };
3018
3019 class VerifyRegionClosure: public HeapRegionClosure {
3020 private:
3021 bool _par;
3022 VerifyOption _vo;
3023 bool _failures;
3024 public:
3025 // _vo == UsePrevMarking -> use "prev" marking information,
3026 // _vo == UseNextMarking -> use "next" marking information,
3027 // _vo == UseMarkWord -> use mark word from object header.
3028 VerifyRegionClosure(bool par, VerifyOption vo)
3029 : _par(par),
3030 _vo(vo),
3031 _failures(false) {}
3032
3033 bool failures() {
3034 return _failures;
3035 }
3036
3037 bool doHeapRegion(HeapRegion* r) {
3038 if (!r->is_continues_humongous()) {
3039 bool failures = false;
3040 r->verify(_vo, &failures);
3041 if (failures) {
3042 _failures = true;
3043 } else {
3044 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3045 r->object_iterate(¬_dead_yet_cl);
3046 if (_vo != VerifyOption_G1UseNextMarking) {
3047 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3048 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3049 "max_live_bytes "SIZE_FORMAT" "
3050 "< calculated "SIZE_FORMAT,
3051 r->bottom(), r->end(),
3052 r->max_live_bytes(),
3053 not_dead_yet_cl.live_bytes());
3054 _failures = true;
3055 }
3056 } else {
3057 // When vo == UseNextMarking we cannot currently do a sanity
3058 // check on the live bytes as the calculation has not been
3059 // finalized yet.
3060 }
3061 }
3062 }
3063 return false; // stop the region iteration if we hit a failure
3064 }
3065 };
3066
3067 // This is the task used for parallel verification of the heap regions
3068
3069 class G1ParVerifyTask: public AbstractGangTask {
3070 private:
3071 G1CollectedHeap* _g1h;
3072 VerifyOption _vo;
3073 bool _failures;
3074 HeapRegionClaimer _hrclaimer;
3075
3076 public:
3077 // _vo == UsePrevMarking -> use "prev" marking information,
3078 // _vo == UseNextMarking -> use "next" marking information,
3079 // _vo == UseMarkWord -> use mark word from object header.
3080 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3081 AbstractGangTask("Parallel verify task"),
3082 _g1h(g1h),
3083 _vo(vo),
3084 _failures(false),
3085 _hrclaimer(g1h->workers()->active_workers()) {}
3086
3087 bool failures() {
3088 return _failures;
3089 }
3090
3091 void work(uint worker_id) {
3092 HandleMark hm;
3093 VerifyRegionClosure blk(true, _vo);
3094 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3095 if (blk.failures()) {
3096 _failures = true;
3097 }
3098 }
3099 };
3100
3101 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3102 if (SafepointSynchronize::is_at_safepoint()) {
3103 assert(Thread::current()->is_VM_thread(),
3104 "Expected to be executed serially by the VM thread at this point");
3105
3106 if (!silent) { gclog_or_tty->print("Roots "); }
3107 VerifyRootsClosure rootsCl(vo);
3108 VerifyKlassClosure klassCl(this, &rootsCl);
3109 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3110
3111 // We apply the relevant closures to all the oops in the
3112 // system dictionary, class loader data graph, the string table
3113 // and the nmethods in the code cache.
3114 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3115 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3116
3117 process_all_roots(true, // activate StrongRootsScope
3118 SO_AllCodeCache, // roots scanning options
3119 &rootsCl,
3120 &cldCl,
3121 &blobsCl);
3122
3123 bool failures = rootsCl.failures() || codeRootsCl.failures();
3124
3125 if (vo != VerifyOption_G1UseMarkWord) {
3126 // If we're verifying during a full GC then the region sets
3127 // will have been torn down at the start of the GC. Therefore
3128 // verifying the region sets will fail. So we only verify
3129 // the region sets when not in a full GC.
3130 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3131 verify_region_sets();
3132 }
3133
3134 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3135 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3136
3137 G1ParVerifyTask task(this, vo);
3138 assert(UseDynamicNumberOfGCThreads ||
3139 workers()->active_workers() == workers()->total_workers(),
3140 "If not dynamic should be using all the workers");
3141 int n_workers = workers()->active_workers();
3142 set_par_threads(n_workers);
3143 workers()->run_task(&task);
3144 set_par_threads(0);
3145 if (task.failures()) {
3146 failures = true;
3147 }
3148
3149 } else {
3150 VerifyRegionClosure blk(false, vo);
3151 heap_region_iterate(&blk);
3152 if (blk.failures()) {
3153 failures = true;
3154 }
3155 }
3156 if (!silent) gclog_or_tty->print("RemSet ");
3157 rem_set()->verify();
3158
3159 if (G1StringDedup::is_enabled()) {
3160 if (!silent) gclog_or_tty->print("StrDedup ");
3161 G1StringDedup::verify();
3162 }
3163
3164 if (failures) {
3165 gclog_or_tty->print_cr("Heap:");
3166 // It helps to have the per-region information in the output to
3167 // help us track down what went wrong. This is why we call
3168 // print_extended_on() instead of print_on().
3169 print_extended_on(gclog_or_tty);
3170 gclog_or_tty->cr();
3171 #ifndef PRODUCT
3172 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3173 concurrent_mark()->print_reachable("at-verification-failure",
3174 vo, false /* all */);
3175 }
3176 #endif
3177 gclog_or_tty->flush();
3178 }
3179 guarantee(!failures, "there should not have been any failures");
3180 } else {
3181 if (!silent) {
3182 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3183 if (G1StringDedup::is_enabled()) {
3184 gclog_or_tty->print(", StrDedup");
3185 }
3186 gclog_or_tty->print(") ");
3187 }
3188 }
3189 }
3190
3191 void G1CollectedHeap::verify(bool silent) {
3192 verify(silent, VerifyOption_G1UsePrevMarking);
3193 }
3194
3195 double G1CollectedHeap::verify(bool guard, const char* msg) {
3196 double verify_time_ms = 0.0;
3197
3198 if (guard && total_collections() >= VerifyGCStartAt) {
3199 double verify_start = os::elapsedTime();
3200 HandleMark hm; // Discard invalid handles created during verification
3201 prepare_for_verify();
3202 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3203 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3204 }
3205
3206 return verify_time_ms;
3207 }
3208
3209 void G1CollectedHeap::verify_before_gc() {
3210 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3211 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3212 }
3213
3214 void G1CollectedHeap::verify_after_gc() {
3215 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3216 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3217 }
3218
3219 class PrintRegionClosure: public HeapRegionClosure {
3220 outputStream* _st;
3221 public:
3222 PrintRegionClosure(outputStream* st) : _st(st) {}
3223 bool doHeapRegion(HeapRegion* r) {
3224 r->print_on(_st);
3225 return false;
3226 }
3227 };
3228
3229 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3230 const HeapRegion* hr,
3231 const VerifyOption vo) const {
3232 switch (vo) {
3233 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3234 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3235 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3236 default: ShouldNotReachHere();
3237 }
3238 return false; // keep some compilers happy
3239 }
3240
3241 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3242 const VerifyOption vo) const {
3243 switch (vo) {
3244 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3245 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3246 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3247 default: ShouldNotReachHere();
3248 }
3249 return false; // keep some compilers happy
3250 }
3251
3252 void G1CollectedHeap::print_on(outputStream* st) const {
3253 st->print(" %-20s", "garbage-first heap");
3254 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3255 capacity()/K, used_unlocked()/K);
3256 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3257 _hrm.reserved().start(),
3258 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3259 _hrm.reserved().end());
3260 st->cr();
3261 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3262 uint young_regions = _young_list->length();
3263 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3264 (size_t) young_regions * HeapRegion::GrainBytes / K);
3265 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3266 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3267 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3268 st->cr();
3269 MetaspaceAux::print_on(st);
3270 }
3271
3272 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3273 print_on(st);
3274
3275 // Print the per-region information.
3276 st->cr();
3277 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3278 "HS=humongous(starts), HC=humongous(continues), "
3279 "CS=collection set, F=free, TS=gc time stamp, "
3280 "PTAMS=previous top-at-mark-start, "
3281 "NTAMS=next top-at-mark-start)");
3282 PrintRegionClosure blk(st);
3283 heap_region_iterate(&blk);
3284 }
3285
3286 void G1CollectedHeap::print_on_error(outputStream* st) const {
3287 this->CollectedHeap::print_on_error(st);
3288
3289 if (_cm != NULL) {
3290 st->cr();
3291 _cm->print_on_error(st);
3292 }
3293 }
3294
3295 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3296 workers()->print_worker_threads_on(st);
3297 _cmThread->print_on(st);
3298 st->cr();
3299 _cm->print_worker_threads_on(st);
3300 _cg1r->print_worker_threads_on(st);
3301 if (G1StringDedup::is_enabled()) {
3302 G1StringDedup::print_worker_threads_on(st);
3303 }
3304 }
3305
3306 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3307 workers()->threads_do(tc);
3308 tc->do_thread(_cmThread);
3309 _cg1r->threads_do(tc);
3310 if (G1StringDedup::is_enabled()) {
3311 G1StringDedup::threads_do(tc);
3312 }
3313 }
3314
3315 void G1CollectedHeap::print_tracing_info() const {
3316 // We'll overload this to mean "trace GC pause statistics."
3317 if (TraceYoungGenTime || TraceOldGenTime) {
3318 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3319 // to that.
3320 g1_policy()->print_tracing_info();
3321 }
3322 if (G1SummarizeRSetStats) {
3323 g1_rem_set()->print_summary_info();
3324 }
3325 if (G1SummarizeConcMark) {
3326 concurrent_mark()->print_summary_info();
3327 }
3328 g1_policy()->print_yg_surv_rate_info();
3329 SpecializationStats::print();
3330 }
3331
3332 #ifndef PRODUCT
3333 // Helpful for debugging RSet issues.
3334
3335 class PrintRSetsClosure : public HeapRegionClosure {
3336 private:
3337 const char* _msg;
3338 size_t _occupied_sum;
3339
3340 public:
3341 bool doHeapRegion(HeapRegion* r) {
3342 HeapRegionRemSet* hrrs = r->rem_set();
3343 size_t occupied = hrrs->occupied();
3344 _occupied_sum += occupied;
3345
3346 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3347 HR_FORMAT_PARAMS(r));
3348 if (occupied == 0) {
3349 gclog_or_tty->print_cr(" RSet is empty");
3350 } else {
3351 hrrs->print();
3352 }
3353 gclog_or_tty->print_cr("----------");
3354 return false;
3355 }
3356
3357 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3358 gclog_or_tty->cr();
3359 gclog_or_tty->print_cr("========================================");
3360 gclog_or_tty->print_cr("%s", msg);
3361 gclog_or_tty->cr();
3362 }
3363
3364 ~PrintRSetsClosure() {
3365 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3366 gclog_or_tty->print_cr("========================================");
3367 gclog_or_tty->cr();
3368 }
3369 };
3370
3371 void G1CollectedHeap::print_cset_rsets() {
3372 PrintRSetsClosure cl("Printing CSet RSets");
3373 collection_set_iterate(&cl);
3374 }
3375
3376 void G1CollectedHeap::print_all_rsets() {
3377 PrintRSetsClosure cl("Printing All RSets");;
3378 heap_region_iterate(&cl);
3379 }
3380 #endif // PRODUCT
3381
3382 G1CollectedHeap* G1CollectedHeap::heap() {
3383 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3384 "not a garbage-first heap");
3385 return _g1h;
3386 }
3387
3388 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3389 // always_do_update_barrier = false;
3390 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3391 // Fill TLAB's and such
3392 accumulate_statistics_all_tlabs();
3393 ensure_parsability(true);
3394
3395 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3396 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3397 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3398 }
3399 }
3400
3401 void G1CollectedHeap::gc_epilogue(bool full) {
3402
3403 if (G1SummarizeRSetStats &&
3404 (G1SummarizeRSetStatsPeriod > 0) &&
3405 // we are at the end of the GC. Total collections has already been increased.
3406 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3407 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3408 }
3409
3410 // FIXME: what is this about?
3411 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3412 // is set.
3413 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3414 "derived pointer present"));
3415 // always_do_update_barrier = true;
3416
3417 resize_all_tlabs();
3418 allocation_context_stats().update(full);
3419
3420 // We have just completed a GC. Update the soft reference
3421 // policy with the new heap occupancy
3422 Universe::update_heap_info_at_gc();
3423 }
3424
3425 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3426 unsigned int gc_count_before,
3427 bool* succeeded,
3428 GCCause::Cause gc_cause) {
3429 assert_heap_not_locked_and_not_at_safepoint();
3430 g1_policy()->record_stop_world_start();
3431 VM_G1IncCollectionPause op(gc_count_before,
3432 word_size,
3433 false, /* should_initiate_conc_mark */
3434 g1_policy()->max_pause_time_ms(),
3435 gc_cause);
3436
3437 op.set_allocation_context(AllocationContext::current());
3438 VMThread::execute(&op);
3439
3440 HeapWord* result = op.result();
3441 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3442 assert(result == NULL || ret_succeeded,
3443 "the result should be NULL if the VM did not succeed");
3444 *succeeded = ret_succeeded;
3445
3446 assert_heap_not_locked();
3447 return result;
3448 }
3449
3450 void
3451 G1CollectedHeap::doConcurrentMark() {
3452 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3453 if (!_cmThread->in_progress()) {
3454 _cmThread->set_started();
3455 CGC_lock->notify();
3456 }
3457 }
3458
3459 size_t G1CollectedHeap::pending_card_num() {
3460 size_t extra_cards = 0;
3461 JavaThread *curr = Threads::first();
3462 while (curr != NULL) {
3463 DirtyCardQueue& dcq = curr->dirty_card_queue();
3464 extra_cards += dcq.size();
3465 curr = curr->next();
3466 }
3467 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3468 size_t buffer_size = dcqs.buffer_size();
3469 size_t buffer_num = dcqs.completed_buffers_num();
3470
3471 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3472 // in bytes - not the number of 'entries'. We need to convert
3473 // into a number of cards.
3474 return (buffer_size * buffer_num + extra_cards) / oopSize;
3475 }
3476
3477 size_t G1CollectedHeap::cards_scanned() {
3478 return g1_rem_set()->cardsScanned();
3479 }
3480
3481 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3482 HeapRegion* region = region_at(index);
3483 assert(region->is_starts_humongous(), "Must start a humongous object");
3484 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3485 }
3486
3487 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3488 private:
3489 size_t _total_humongous;
3490 size_t _candidate_humongous;
3491 public:
3492 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3493 }
3494
3495 virtual bool doHeapRegion(HeapRegion* r) {
3496 if (!r->is_starts_humongous()) {
3497 return false;
3498 }
3499 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3500
3501 uint region_idx = r->hrm_index();
3502 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3503 // Is_candidate already filters out humongous regions with some remembered set.
3504 // This will not lead to humongous object that we mistakenly keep alive because
3505 // during young collection the remembered sets will only be added to.
3506 if (is_candidate) {
3507 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3508 _candidate_humongous++;
3509 }
3510 _total_humongous++;
3511
3512 return false;
3513 }
3514
3515 size_t total_humongous() const { return _total_humongous; }
3516 size_t candidate_humongous() const { return _candidate_humongous; }
3517 };
3518
3519 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3520 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3521 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3522 return;
3523 }
3524
3525 RegisterHumongousWithInCSetFastTestClosure cl;
3526 heap_region_iterate(&cl);
3527 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3528 cl.candidate_humongous());
3529 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3530
3531 if (_has_humongous_reclaim_candidates || G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
3532 clear_humongous_is_live_table();
3533 }
3534 }
3535
3536 void
3537 G1CollectedHeap::setup_surviving_young_words() {
3538 assert(_surviving_young_words == NULL, "pre-condition");
3539 uint array_length = g1_policy()->young_cset_region_length();
3540 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3541 if (_surviving_young_words == NULL) {
3542 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3543 "Not enough space for young surv words summary.");
3544 }
3545 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3546 #ifdef ASSERT
3547 for (uint i = 0; i < array_length; ++i) {
3548 assert( _surviving_young_words[i] == 0, "memset above" );
3549 }
3550 #endif // !ASSERT
3551 }
3552
3553 void
3554 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3555 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3556 uint array_length = g1_policy()->young_cset_region_length();
3557 for (uint i = 0; i < array_length; ++i) {
3558 _surviving_young_words[i] += surv_young_words[i];
3559 }
3560 }
3561
3562 void
3563 G1CollectedHeap::cleanup_surviving_young_words() {
3564 guarantee( _surviving_young_words != NULL, "pre-condition" );
3565 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3566 _surviving_young_words = NULL;
3567 }
3568
3569 #ifdef ASSERT
3570 class VerifyCSetClosure: public HeapRegionClosure {
3571 public:
3572 bool doHeapRegion(HeapRegion* hr) {
3573 // Here we check that the CSet region's RSet is ready for parallel
3574 // iteration. The fields that we'll verify are only manipulated
3575 // when the region is part of a CSet and is collected. Afterwards,
3576 // we reset these fields when we clear the region's RSet (when the
3577 // region is freed) so they are ready when the region is
3578 // re-allocated. The only exception to this is if there's an
3579 // evacuation failure and instead of freeing the region we leave
3580 // it in the heap. In that case, we reset these fields during
3581 // evacuation failure handling.
3582 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3583
3584 // Here's a good place to add any other checks we'd like to
3585 // perform on CSet regions.
3586 return false;
3587 }
3588 };
3589 #endif // ASSERT
3590
3591 #if TASKQUEUE_STATS
3592 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3593 st->print_raw_cr("GC Task Stats");
3594 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3595 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3596 }
3597
3598 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3599 print_taskqueue_stats_hdr(st);
3600
3601 TaskQueueStats totals;
3602 const int n = workers()->total_workers();
3603 for (int i = 0; i < n; ++i) {
3604 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3605 totals += task_queue(i)->stats;
3606 }
3607 st->print_raw("tot "); totals.print(st); st->cr();
3608
3609 DEBUG_ONLY(totals.verify());
3610 }
3611
3612 void G1CollectedHeap::reset_taskqueue_stats() {
3613 const int n = workers()->total_workers();
3614 for (int i = 0; i < n; ++i) {
3615 task_queue(i)->stats.reset();
3616 }
3617 }
3618 #endif // TASKQUEUE_STATS
3619
3620 void G1CollectedHeap::log_gc_header() {
3621 if (!G1Log::fine()) {
3622 return;
3623 }
3624
3625 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3626
3627 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3628 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3629 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3630
3631 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3632 }
3633
3634 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3635 if (!G1Log::fine()) {
3636 return;
3637 }
3638
3639 if (G1Log::finer()) {
3640 if (evacuation_failed()) {
3641 gclog_or_tty->print(" (to-space exhausted)");
3642 }
3643 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3644 g1_policy()->phase_times()->note_gc_end();
3645 g1_policy()->phase_times()->print(pause_time_sec);
3646 g1_policy()->print_detailed_heap_transition();
3647 } else {
3648 if (evacuation_failed()) {
3649 gclog_or_tty->print("--");
3650 }
3651 g1_policy()->print_heap_transition();
3652 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3653 }
3654 gclog_or_tty->flush();
3655 }
3656
3657 bool
3658 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3659 assert_at_safepoint(true /* should_be_vm_thread */);
3660 guarantee(!is_gc_active(), "collection is not reentrant");
3661
3662 if (GC_locker::check_active_before_gc()) {
3663 return false;
3664 }
3665
3666 _gc_timer_stw->register_gc_start();
3667
3668 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3669
3670 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3671 ResourceMark rm;
3672
3673 print_heap_before_gc();
3674 trace_heap_before_gc(_gc_tracer_stw);
3675
3676 verify_region_sets_optional();
3677 verify_dirty_young_regions();
3678
3679 // This call will decide whether this pause is an initial-mark
3680 // pause. If it is, during_initial_mark_pause() will return true
3681 // for the duration of this pause.
3682 g1_policy()->decide_on_conc_mark_initiation();
3683
3684 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3685 assert(!g1_policy()->during_initial_mark_pause() ||
3686 g1_policy()->gcs_are_young(), "sanity");
3687
3688 // We also do not allow mixed GCs during marking.
3689 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3690
3691 // Record whether this pause is an initial mark. When the current
3692 // thread has completed its logging output and it's safe to signal
3693 // the CM thread, the flag's value in the policy has been reset.
3694 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3695
3696 // Inner scope for scope based logging, timers, and stats collection
3697 {
3698 EvacuationInfo evacuation_info;
3699
3700 if (g1_policy()->during_initial_mark_pause()) {
3701 // We are about to start a marking cycle, so we increment the
3702 // full collection counter.
3703 increment_old_marking_cycles_started();
3704 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3705 }
3706
3707 _gc_tracer_stw->report_yc_type(yc_type());
3708
3709 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3710
3711 int active_workers = workers()->active_workers();
3712 double pause_start_sec = os::elapsedTime();
3713 g1_policy()->phase_times()->note_gc_start(active_workers);
3714 log_gc_header();
3715
3716 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3717 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3718
3719 // If the secondary_free_list is not empty, append it to the
3720 // free_list. No need to wait for the cleanup operation to finish;
3721 // the region allocation code will check the secondary_free_list
3722 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3723 // set, skip this step so that the region allocation code has to
3724 // get entries from the secondary_free_list.
3725 if (!G1StressConcRegionFreeing) {
3726 append_secondary_free_list_if_not_empty_with_lock();
3727 }
3728
3729 assert(check_young_list_well_formed(), "young list should be well formed");
3730
3731 // Don't dynamically change the number of GC threads this early. A value of
3732 // 0 is used to indicate serial work. When parallel work is done,
3733 // it will be set.
3734
3735 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3736 IsGCActiveMark x;
3737
3738 gc_prologue(false);
3739 increment_total_collections(false /* full gc */);
3740 increment_gc_time_stamp();
3741
3742 verify_before_gc();
3743
3744 check_bitmaps("GC Start");
3745
3746 COMPILER2_PRESENT(DerivedPointerTable::clear());
3747
3748 // Please see comment in g1CollectedHeap.hpp and
3749 // G1CollectedHeap::ref_processing_init() to see how
3750 // reference processing currently works in G1.
3751
3752 // Enable discovery in the STW reference processor
3753 ref_processor_stw()->enable_discovery();
3754
3755 {
3756 // We want to temporarily turn off discovery by the
3757 // CM ref processor, if necessary, and turn it back on
3758 // on again later if we do. Using a scoped
3759 // NoRefDiscovery object will do this.
3760 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3761
3762 // Forget the current alloc region (we might even choose it to be part
3763 // of the collection set!).
3764 _allocator->release_mutator_alloc_region();
3765
3766 // We should call this after we retire the mutator alloc
3767 // region(s) so that all the ALLOC / RETIRE events are generated
3768 // before the start GC event.
3769 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3770
3771 // This timing is only used by the ergonomics to handle our pause target.
3772 // It is unclear why this should not include the full pause. We will
3773 // investigate this in CR 7178365.
3774 //
3775 // Preserving the old comment here if that helps the investigation:
3776 //
3777 // The elapsed time induced by the start time below deliberately elides
3778 // the possible verification above.
3779 double sample_start_time_sec = os::elapsedTime();
3780
3781 #if YOUNG_LIST_VERBOSE
3782 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3783 _young_list->print();
3784 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3785 #endif // YOUNG_LIST_VERBOSE
3786
3787 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3788
3789 double scan_wait_start = os::elapsedTime();
3790 // We have to wait until the CM threads finish scanning the
3791 // root regions as it's the only way to ensure that all the
3792 // objects on them have been correctly scanned before we start
3793 // moving them during the GC.
3794 bool waited = _cm->root_regions()->wait_until_scan_finished();
3795 double wait_time_ms = 0.0;
3796 if (waited) {
3797 double scan_wait_end = os::elapsedTime();
3798 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3799 }
3800 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3801
3802 #if YOUNG_LIST_VERBOSE
3803 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3804 _young_list->print();
3805 #endif // YOUNG_LIST_VERBOSE
3806
3807 if (g1_policy()->during_initial_mark_pause()) {
3808 concurrent_mark()->checkpointRootsInitialPre();
3809 }
3810
3811 #if YOUNG_LIST_VERBOSE
3812 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3813 _young_list->print();
3814 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3815 #endif // YOUNG_LIST_VERBOSE
3816
3817 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3818
3819 register_humongous_regions_with_in_cset_fast_test();
3820
3821 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3822
3823 _cm->note_start_of_gc();
3824 // We should not verify the per-thread SATB buffers given that
3825 // we have not filtered them yet (we'll do so during the
3826 // GC). We also call this after finalize_cset() to
3827 // ensure that the CSet has been finalized.
3828 _cm->verify_no_cset_oops(true /* verify_stacks */,
3829 true /* verify_enqueued_buffers */,
3830 false /* verify_thread_buffers */,
3831 true /* verify_fingers */);
3832
3833 if (_hr_printer.is_active()) {
3834 HeapRegion* hr = g1_policy()->collection_set();
3835 while (hr != NULL) {
3836 _hr_printer.cset(hr);
3837 hr = hr->next_in_collection_set();
3838 }
3839 }
3840
3841 #ifdef ASSERT
3842 VerifyCSetClosure cl;
3843 collection_set_iterate(&cl);
3844 #endif // ASSERT
3845
3846 setup_surviving_young_words();
3847
3848 // Initialize the GC alloc regions.
3849 _allocator->init_gc_alloc_regions(evacuation_info);
3850
3851 // Actually do the work...
3852 evacuate_collection_set(evacuation_info);
3853
3854 // We do this to mainly verify the per-thread SATB buffers
3855 // (which have been filtered by now) since we didn't verify
3856 // them earlier. No point in re-checking the stacks / enqueued
3857 // buffers given that the CSet has not changed since last time
3858 // we checked.
3859 _cm->verify_no_cset_oops(false /* verify_stacks */,
3860 false /* verify_enqueued_buffers */,
3861 true /* verify_thread_buffers */,
3862 true /* verify_fingers */);
3863
3864 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3865
3866 eagerly_reclaim_humongous_regions();
3867
3868 g1_policy()->clear_collection_set();
3869
3870 cleanup_surviving_young_words();
3871
3872 // Start a new incremental collection set for the next pause.
3873 g1_policy()->start_incremental_cset_building();
3874
3875 clear_cset_fast_test();
3876
3877 _young_list->reset_sampled_info();
3878
3879 // Don't check the whole heap at this point as the
3880 // GC alloc regions from this pause have been tagged
3881 // as survivors and moved on to the survivor list.
3882 // Survivor regions will fail the !is_young() check.
3883 assert(check_young_list_empty(false /* check_heap */),
3884 "young list should be empty");
3885
3886 #if YOUNG_LIST_VERBOSE
3887 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3888 _young_list->print();
3889 #endif // YOUNG_LIST_VERBOSE
3890
3891 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3892 _young_list->first_survivor_region(),
3893 _young_list->last_survivor_region());
3894
3895 _young_list->reset_auxilary_lists();
3896
3897 if (evacuation_failed()) {
3898 _allocator->set_used(recalculate_used());
3899 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3900 for (uint i = 0; i < n_queues; i++) {
3901 if (_evacuation_failed_info_array[i].has_failed()) {
3902 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3903 }
3904 }
3905 } else {
3906 // The "used" of the the collection set have already been subtracted
3907 // when they were freed. Add in the bytes evacuated.
3908 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3909 }
3910
3911 if (g1_policy()->during_initial_mark_pause()) {
3912 // We have to do this before we notify the CM threads that
3913 // they can start working to make sure that all the
3914 // appropriate initialization is done on the CM object.
3915 concurrent_mark()->checkpointRootsInitialPost();
3916 set_marking_started();
3917 // Note that we don't actually trigger the CM thread at
3918 // this point. We do that later when we're sure that
3919 // the current thread has completed its logging output.
3920 }
3921
3922 allocate_dummy_regions();
3923
3924 #if YOUNG_LIST_VERBOSE
3925 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3926 _young_list->print();
3927 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3928 #endif // YOUNG_LIST_VERBOSE
3929
3930 _allocator->init_mutator_alloc_region();
3931
3932 {
3933 size_t expand_bytes = g1_policy()->expansion_amount();
3934 if (expand_bytes > 0) {
3935 size_t bytes_before = capacity();
3936 // No need for an ergo verbose message here,
3937 // expansion_amount() does this when it returns a value > 0.
3938 if (!expand(expand_bytes)) {
3939 // We failed to expand the heap. Cannot do anything about it.
3940 }
3941 }
3942 }
3943
3944 // We redo the verification but now wrt to the new CSet which
3945 // has just got initialized after the previous CSet was freed.
3946 _cm->verify_no_cset_oops(true /* verify_stacks */,
3947 true /* verify_enqueued_buffers */,
3948 true /* verify_thread_buffers */,
3949 true /* verify_fingers */);
3950 _cm->note_end_of_gc();
3951
3952 // This timing is only used by the ergonomics to handle our pause target.
3953 // It is unclear why this should not include the full pause. We will
3954 // investigate this in CR 7178365.
3955 double sample_end_time_sec = os::elapsedTime();
3956 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3957 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3958
3959 MemoryService::track_memory_usage();
3960
3961 // In prepare_for_verify() below we'll need to scan the deferred
3962 // update buffers to bring the RSets up-to-date if
3963 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3964 // the update buffers we'll probably need to scan cards on the
3965 // regions we just allocated to (i.e., the GC alloc
3966 // regions). However, during the last GC we called
3967 // set_saved_mark() on all the GC alloc regions, so card
3968 // scanning might skip the [saved_mark_word()...top()] area of
3969 // those regions (i.e., the area we allocated objects into
3970 // during the last GC). But it shouldn't. Given that
3971 // saved_mark_word() is conditional on whether the GC time stamp
3972 // on the region is current or not, by incrementing the GC time
3973 // stamp here we invalidate all the GC time stamps on all the
3974 // regions and saved_mark_word() will simply return top() for
3975 // all the regions. This is a nicer way of ensuring this rather
3976 // than iterating over the regions and fixing them. In fact, the
3977 // GC time stamp increment here also ensures that
3978 // saved_mark_word() will return top() between pauses, i.e.,
3979 // during concurrent refinement. So we don't need the
3980 // is_gc_active() check to decided which top to use when
3981 // scanning cards (see CR 7039627).
3982 increment_gc_time_stamp();
3983
3984 verify_after_gc();
3985 check_bitmaps("GC End");
3986
3987 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3988 ref_processor_stw()->verify_no_references_recorded();
3989
3990 // CM reference discovery will be re-enabled if necessary.
3991 }
3992
3993 // We should do this after we potentially expand the heap so
3994 // that all the COMMIT events are generated before the end GC
3995 // event, and after we retire the GC alloc regions so that all
3996 // RETIRE events are generated before the end GC event.
3997 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3998
3999 #ifdef TRACESPINNING
4000 ParallelTaskTerminator::print_termination_counts();
4001 #endif
4002
4003 gc_epilogue(false);
4004 }
4005
4006 // Print the remainder of the GC log output.
4007 log_gc_footer(os::elapsedTime() - pause_start_sec);
4008
4009 // It is not yet to safe to tell the concurrent mark to
4010 // start as we have some optional output below. We don't want the
4011 // output from the concurrent mark thread interfering with this
4012 // logging output either.
4013
4014 _hrm.verify_optional();
4015 verify_region_sets_optional();
4016
4017 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4018 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4019
4020 print_heap_after_gc();
4021 trace_heap_after_gc(_gc_tracer_stw);
4022
4023 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4024 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4025 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4026 // before any GC notifications are raised.
4027 g1mm()->update_sizes();
4028
4029 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4030 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4031 _gc_timer_stw->register_gc_end();
4032 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4033 }
4034 // It should now be safe to tell the concurrent mark thread to start
4035 // without its logging output interfering with the logging output
4036 // that came from the pause.
4037
4038 if (should_start_conc_mark) {
4039 // CAUTION: after the doConcurrentMark() call below,
4040 // the concurrent marking thread(s) could be running
4041 // concurrently with us. Make sure that anything after
4042 // this point does not assume that we are the only GC thread
4043 // running. Note: of course, the actual marking work will
4044 // not start until the safepoint itself is released in
4045 // SuspendibleThreadSet::desynchronize().
4046 doConcurrentMark();
4047 }
4048
4049 return true;
4050 }
4051
4052 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4053 _drain_in_progress = false;
4054 set_evac_failure_closure(cl);
4055 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4056 }
4057
4058 void G1CollectedHeap::finalize_for_evac_failure() {
4059 assert(_evac_failure_scan_stack != NULL &&
4060 _evac_failure_scan_stack->length() == 0,
4061 "Postcondition");
4062 assert(!_drain_in_progress, "Postcondition");
4063 delete _evac_failure_scan_stack;
4064 _evac_failure_scan_stack = NULL;
4065 }
4066
4067 void G1CollectedHeap::remove_self_forwarding_pointers() {
4068 double remove_self_forwards_start = os::elapsedTime();
4069
4070 set_par_threads();
4071 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4072 workers()->run_task(&rsfp_task);
4073 set_par_threads(0);
4074
4075 // Now restore saved marks, if any.
4076 assert(_objs_with_preserved_marks.size() ==
4077 _preserved_marks_of_objs.size(), "Both or none.");
4078 while (!_objs_with_preserved_marks.is_empty()) {
4079 oop obj = _objs_with_preserved_marks.pop();
4080 markOop m = _preserved_marks_of_objs.pop();
4081 obj->set_mark(m);
4082 }
4083 _objs_with_preserved_marks.clear(true);
4084 _preserved_marks_of_objs.clear(true);
4085
4086 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4087 }
4088
4089 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4090 _evac_failure_scan_stack->push(obj);
4091 }
4092
4093 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4094 assert(_evac_failure_scan_stack != NULL, "precondition");
4095
4096 while (_evac_failure_scan_stack->length() > 0) {
4097 oop obj = _evac_failure_scan_stack->pop();
4098 _evac_failure_closure->set_region(heap_region_containing(obj));
4099 obj->oop_iterate_backwards(_evac_failure_closure);
4100 }
4101 }
4102
4103 oop
4104 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4105 oop old) {
4106 assert(obj_in_cs(old),
4107 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4108 (HeapWord*) old));
4109 markOop m = old->mark();
4110 oop forward_ptr = old->forward_to_atomic(old);
4111 if (forward_ptr == NULL) {
4112 // Forward-to-self succeeded.
4113 assert(_par_scan_state != NULL, "par scan state");
4114 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4115 uint queue_num = _par_scan_state->queue_num();
4116
4117 _evacuation_failed = true;
4118 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4119 if (_evac_failure_closure != cl) {
4120 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4121 assert(!_drain_in_progress,
4122 "Should only be true while someone holds the lock.");
4123 // Set the global evac-failure closure to the current thread's.
4124 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4125 set_evac_failure_closure(cl);
4126 // Now do the common part.
4127 handle_evacuation_failure_common(old, m);
4128 // Reset to NULL.
4129 set_evac_failure_closure(NULL);
4130 } else {
4131 // The lock is already held, and this is recursive.
4132 assert(_drain_in_progress, "This should only be the recursive case.");
4133 handle_evacuation_failure_common(old, m);
4134 }
4135 return old;
4136 } else {
4137 // Forward-to-self failed. Either someone else managed to allocate
4138 // space for this object (old != forward_ptr) or they beat us in
4139 // self-forwarding it (old == forward_ptr).
4140 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4141 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4142 "should not be in the CSet",
4143 (HeapWord*) old, (HeapWord*) forward_ptr));
4144 return forward_ptr;
4145 }
4146 }
4147
4148 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4149 preserve_mark_if_necessary(old, m);
4150
4151 HeapRegion* r = heap_region_containing(old);
4152 if (!r->evacuation_failed()) {
4153 r->set_evacuation_failed(true);
4154 _hr_printer.evac_failure(r);
4155 }
4156
4157 push_on_evac_failure_scan_stack(old);
4158
4159 if (!_drain_in_progress) {
4160 // prevent recursion in copy_to_survivor_space()
4161 _drain_in_progress = true;
4162 drain_evac_failure_scan_stack();
4163 _drain_in_progress = false;
4164 }
4165 }
4166
4167 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4168 assert(evacuation_failed(), "Oversaving!");
4169 // We want to call the "for_promotion_failure" version only in the
4170 // case of a promotion failure.
4171 if (m->must_be_preserved_for_promotion_failure(obj)) {
4172 _objs_with_preserved_marks.push(obj);
4173 _preserved_marks_of_objs.push(m);
4174 }
4175 }
4176
4177 void G1ParCopyHelper::mark_object(oop obj) {
4178 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4179
4180 // We know that the object is not moving so it's safe to read its size.
4181 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4182 }
4183
4184 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4185 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4186 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4187 assert(from_obj != to_obj, "should not be self-forwarded");
4188
4189 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4190 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4191
4192 // The object might be in the process of being copied by another
4193 // worker so we cannot trust that its to-space image is
4194 // well-formed. So we have to read its size from its from-space
4195 // image which we know should not be changing.
4196 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4197 }
4198
4199 template <class T>
4200 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4201 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4202 _scanned_klass->record_modified_oops();
4203 }
4204 }
4205
4206 template <G1Barrier barrier, G1Mark do_mark_object>
4207 template <class T>
4208 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4209 T heap_oop = oopDesc::load_heap_oop(p);
4210
4211 if (oopDesc::is_null(heap_oop)) {
4212 return;
4213 }
4214
4215 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4216
4217 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4218
4219 const InCSetState state = _g1->in_cset_state(obj);
4220 if (state.is_in_cset()) {
4221 oop forwardee;
4222 markOop m = obj->mark();
4223 if (m->is_marked()) {
4224 forwardee = (oop) m->decode_pointer();
4225 } else {
4226 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4227 }
4228 assert(forwardee != NULL, "forwardee should not be NULL");
4229 oopDesc::encode_store_heap_oop(p, forwardee);
4230 if (do_mark_object != G1MarkNone && forwardee != obj) {
4231 // If the object is self-forwarded we don't need to explicitly
4232 // mark it, the evacuation failure protocol will do so.
4233 mark_forwarded_object(obj, forwardee);
4234 }
4235
4236 if (barrier == G1BarrierKlass) {
4237 do_klass_barrier(p, forwardee);
4238 }
4239 } else {
4240 if (state.is_humongous()) {
4241 _g1->set_humongous_is_live(obj);
4242 }
4243 // The object is not in collection set. If we're a root scanning
4244 // closure during an initial mark pause then attempt to mark the object.
4245 if (do_mark_object == G1MarkFromRoot) {
4246 mark_object(obj);
4247 }
4248 }
4249
4250 if (barrier == G1BarrierEvac) {
4251 _par_scan_state->update_rs(_from, p, _worker_id);
4252 }
4253 }
4254
4255 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4256 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4257
4258 class G1ParEvacuateFollowersClosure : public VoidClosure {
4259 protected:
4260 G1CollectedHeap* _g1h;
4261 G1ParScanThreadState* _par_scan_state;
4262 RefToScanQueueSet* _queues;
4263 ParallelTaskTerminator* _terminator;
4264
4265 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4266 RefToScanQueueSet* queues() { return _queues; }
4267 ParallelTaskTerminator* terminator() { return _terminator; }
4268
4269 public:
4270 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4271 G1ParScanThreadState* par_scan_state,
4272 RefToScanQueueSet* queues,
4273 ParallelTaskTerminator* terminator)
4274 : _g1h(g1h), _par_scan_state(par_scan_state),
4275 _queues(queues), _terminator(terminator) {}
4276
4277 void do_void();
4278
4279 private:
4280 inline bool offer_termination();
4281 };
4282
4283 bool G1ParEvacuateFollowersClosure::offer_termination() {
4284 G1ParScanThreadState* const pss = par_scan_state();
4285 pss->start_term_time();
4286 const bool res = terminator()->offer_termination();
4287 pss->end_term_time();
4288 return res;
4289 }
4290
4291 void G1ParEvacuateFollowersClosure::do_void() {
4292 G1ParScanThreadState* const pss = par_scan_state();
4293 pss->trim_queue();
4294 do {
4295 pss->steal_and_trim_queue(queues());
4296 } while (!offer_termination());
4297 }
4298
4299 class G1KlassScanClosure : public KlassClosure {
4300 G1ParCopyHelper* _closure;
4301 bool _process_only_dirty;
4302 int _count;
4303 public:
4304 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4305 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4306 void do_klass(Klass* klass) {
4307 // If the klass has not been dirtied we know that there's
4308 // no references into the young gen and we can skip it.
4309 if (!_process_only_dirty || klass->has_modified_oops()) {
4310 // Clean the klass since we're going to scavenge all the metadata.
4311 klass->clear_modified_oops();
4312
4313 // Tell the closure that this klass is the Klass to scavenge
4314 // and is the one to dirty if oops are left pointing into the young gen.
4315 _closure->set_scanned_klass(klass);
4316
4317 klass->oops_do(_closure);
4318
4319 _closure->set_scanned_klass(NULL);
4320 }
4321 _count++;
4322 }
4323 };
4324
4325 class G1CodeBlobClosure : public CodeBlobClosure {
4326 class HeapRegionGatheringOopClosure : public OopClosure {
4327 G1CollectedHeap* _g1h;
4328 OopClosure* _work;
4329 nmethod* _nm;
4330
4331 template <typename T>
4332 void do_oop_work(T* p) {
4333 _work->do_oop(p);
4334 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4335 if (!oopDesc::is_null(oop_or_narrowoop)) {
4336 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4337 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4338 assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset");
4339 hr->add_strong_code_root(_nm);
4340 }
4341 }
4342
4343 public:
4344 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4345
4346 void do_oop(oop* o) {
4347 do_oop_work(o);
4348 }
4349
4350 void do_oop(narrowOop* o) {
4351 do_oop_work(o);
4352 }
4353
4354 void set_nm(nmethod* nm) {
4355 _nm = nm;
4356 }
4357 };
4358
4359 HeapRegionGatheringOopClosure _oc;
4360 public:
4361 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4362
4363 void do_code_blob(CodeBlob* cb) {
4364 nmethod* nm = cb->as_nmethod_or_null();
4365 if (nm != NULL) {
4366 if (!nm->test_set_oops_do_mark()) {
4367 _oc.set_nm(nm);
4368 nm->oops_do(&_oc);
4369 nm->fix_oop_relocations();
4370 }
4371 }
4372 }
4373 };
4374
4375 class G1ParTask : public AbstractGangTask {
4376 protected:
4377 G1CollectedHeap* _g1h;
4378 RefToScanQueueSet *_queues;
4379 ParallelTaskTerminator _terminator;
4380 uint _n_workers;
4381
4382 Mutex _stats_lock;
4383 Mutex* stats_lock() { return &_stats_lock; }
4384
4385 public:
4386 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4387 : AbstractGangTask("G1 collection"),
4388 _g1h(g1h),
4389 _queues(task_queues),
4390 _terminator(0, _queues),
4391 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4392 {}
4393
4394 RefToScanQueueSet* queues() { return _queues; }
4395
4396 RefToScanQueue *work_queue(int i) {
4397 return queues()->queue(i);
4398 }
4399
4400 ParallelTaskTerminator* terminator() { return &_terminator; }
4401
4402 virtual void set_for_termination(int active_workers) {
4403 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4404 // in the young space (_par_seq_tasks) in the G1 heap
4405 // for SequentialSubTasksDone.
4406 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4407 // both of which need setting by set_n_termination().
4408 _g1h->SharedHeap::set_n_termination(active_workers);
4409 _g1h->set_n_termination(active_workers);
4410 terminator()->reset_for_reuse(active_workers);
4411 _n_workers = active_workers;
4412 }
4413
4414 // Helps out with CLD processing.
4415 //
4416 // During InitialMark we need to:
4417 // 1) Scavenge all CLDs for the young GC.
4418 // 2) Mark all objects directly reachable from strong CLDs.
4419 template <G1Mark do_mark_object>
4420 class G1CLDClosure : public CLDClosure {
4421 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4422 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4423 G1KlassScanClosure _klass_in_cld_closure;
4424 bool _claim;
4425
4426 public:
4427 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4428 bool only_young, bool claim)
4429 : _oop_closure(oop_closure),
4430 _oop_in_klass_closure(oop_closure->g1(),
4431 oop_closure->pss(),
4432 oop_closure->rp()),
4433 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4434 _claim(claim) {
4435
4436 }
4437
4438 void do_cld(ClassLoaderData* cld) {
4439 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4440 }
4441 };
4442
4443 void work(uint worker_id) {
4444 if (worker_id >= _n_workers) return; // no work needed this round
4445
4446 double start_time_ms = os::elapsedTime() * 1000.0;
4447 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4448
4449 {
4450 ResourceMark rm;
4451 HandleMark hm;
4452
4453 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4454
4455 G1ParScanThreadState pss(_g1h, worker_id, rp);
4456 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4457
4458 pss.set_evac_failure_closure(&evac_failure_cl);
4459
4460 bool only_young = _g1h->g1_policy()->gcs_are_young();
4461
4462 // Non-IM young GC.
4463 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4464 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4465 only_young, // Only process dirty klasses.
4466 false); // No need to claim CLDs.
4467 // IM young GC.
4468 // Strong roots closures.
4469 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4470 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4471 false, // Process all klasses.
4472 true); // Need to claim CLDs.
4473 // Weak roots closures.
4474 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4475 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4476 false, // Process all klasses.
4477 true); // Need to claim CLDs.
4478
4479 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4480 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4481 // IM Weak code roots are handled later.
4482
4483 OopClosure* strong_root_cl;
4484 OopClosure* weak_root_cl;
4485 CLDClosure* strong_cld_cl;
4486 CLDClosure* weak_cld_cl;
4487 CodeBlobClosure* strong_code_cl;
4488
4489 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4490 // We also need to mark copied objects.
4491 strong_root_cl = &scan_mark_root_cl;
4492 strong_cld_cl = &scan_mark_cld_cl;
4493 strong_code_cl = &scan_mark_code_cl;
4494 if (ClassUnloadingWithConcurrentMark) {
4495 weak_root_cl = &scan_mark_weak_root_cl;
4496 weak_cld_cl = &scan_mark_weak_cld_cl;
4497 } else {
4498 weak_root_cl = &scan_mark_root_cl;
4499 weak_cld_cl = &scan_mark_cld_cl;
4500 }
4501 } else {
4502 strong_root_cl = &scan_only_root_cl;
4503 weak_root_cl = &scan_only_root_cl;
4504 strong_cld_cl = &scan_only_cld_cl;
4505 weak_cld_cl = &scan_only_cld_cl;
4506 strong_code_cl = &scan_only_code_cl;
4507 }
4508
4509
4510 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4511
4512 pss.start_strong_roots();
4513 _g1h->g1_process_roots(strong_root_cl,
4514 weak_root_cl,
4515 &push_heap_rs_cl,
4516 strong_cld_cl,
4517 weak_cld_cl,
4518 strong_code_cl,
4519 worker_id);
4520
4521 pss.end_strong_roots();
4522
4523 {
4524 double start = os::elapsedTime();
4525 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4526 evac.do_void();
4527 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4528 double term_ms = pss.term_time()*1000.0;
4529 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4530 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4531 }
4532 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4533 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4534
4535 if (PrintTerminationStats) {
4536 MutexLocker x(stats_lock());
4537 pss.print_termination_stats(worker_id);
4538 }
4539
4540 assert(pss.queue_is_empty(), "should be empty");
4541
4542 // Close the inner scope so that the ResourceMark and HandleMark
4543 // destructors are executed here and are included as part of the
4544 // "GC Worker Time".
4545 }
4546
4547 double end_time_ms = os::elapsedTime() * 1000.0;
4548 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4549 }
4550 };
4551
4552 // *** Common G1 Evacuation Stuff
4553
4554 // This method is run in a GC worker.
4555
4556 void
4557 G1CollectedHeap::
4558 g1_process_roots(OopClosure* scan_non_heap_roots,
4559 OopClosure* scan_non_heap_weak_roots,
4560 G1ParPushHeapRSClosure* scan_rs,
4561 CLDClosure* scan_strong_clds,
4562 CLDClosure* scan_weak_clds,
4563 CodeBlobClosure* scan_strong_code,
4564 uint worker_i) {
4565
4566 // First scan the shared roots.
4567 double ext_roots_start = os::elapsedTime();
4568 double closure_app_time_sec = 0.0;
4569
4570 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4571 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4572
4573 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4574 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4575
4576 process_roots(false, // no scoping; this is parallel code
4577 SharedHeap::SO_None,
4578 &buf_scan_non_heap_roots,
4579 &buf_scan_non_heap_weak_roots,
4580 scan_strong_clds,
4581 // Unloading Initial Marks handle the weak CLDs separately.
4582 (trace_metadata ? NULL : scan_weak_clds),
4583 scan_strong_code);
4584
4585 // Now the CM ref_processor roots.
4586 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4587 // We need to treat the discovered reference lists of the
4588 // concurrent mark ref processor as roots and keep entries
4589 // (which are added by the marking threads) on them live
4590 // until they can be processed at the end of marking.
4591 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4592 }
4593
4594 if (trace_metadata) {
4595 // Barrier to make sure all workers passed
4596 // the strong CLD and strong nmethods phases.
4597 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4598
4599 // Now take the complement of the strong CLDs.
4600 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4601 }
4602
4603 // Finish up any enqueued closure apps (attributed as object copy time).
4604 buf_scan_non_heap_roots.done();
4605 buf_scan_non_heap_weak_roots.done();
4606
4607 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4608 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4609
4610 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4611
4612 double ext_root_time_ms =
4613 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4614
4615 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4616
4617 // During conc marking we have to filter the per-thread SATB buffers
4618 // to make sure we remove any oops into the CSet (which will show up
4619 // as implicitly live).
4620 double satb_filtering_ms = 0.0;
4621 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4622 if (mark_in_progress()) {
4623 double satb_filter_start = os::elapsedTime();
4624
4625 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4626
4627 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4628 }
4629 }
4630 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4631
4632 // Now scan the complement of the collection set.
4633 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4634
4635 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4636
4637 _process_strong_tasks->all_tasks_completed();
4638 }
4639
4640 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4641 private:
4642 BoolObjectClosure* _is_alive;
4643 int _initial_string_table_size;
4644 int _initial_symbol_table_size;
4645
4646 bool _process_strings;
4647 int _strings_processed;
4648 int _strings_removed;
4649
4650 bool _process_symbols;
4651 int _symbols_processed;
4652 int _symbols_removed;
4653
4654 public:
4655 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4656 AbstractGangTask("String/Symbol Unlinking"),
4657 _is_alive(is_alive),
4658 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4659 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4660
4661 _initial_string_table_size = StringTable::the_table()->table_size();
4662 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4663 if (process_strings) {
4664 StringTable::clear_parallel_claimed_index();
4665 }
4666 if (process_symbols) {
4667 SymbolTable::clear_parallel_claimed_index();
4668 }
4669 }
4670
4671 ~G1StringSymbolTableUnlinkTask() {
4672 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4673 err_msg("claim value %d after unlink less than initial string table size %d",
4674 StringTable::parallel_claimed_index(), _initial_string_table_size));
4675 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4676 err_msg("claim value %d after unlink less than initial symbol table size %d",
4677 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4678
4679 if (G1TraceStringSymbolTableScrubbing) {
4680 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4681 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4682 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4683 strings_processed(), strings_removed(),
4684 symbols_processed(), symbols_removed());
4685 }
4686 }
4687
4688 void work(uint worker_id) {
4689 int strings_processed = 0;
4690 int strings_removed = 0;
4691 int symbols_processed = 0;
4692 int symbols_removed = 0;
4693 if (_process_strings) {
4694 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4695 Atomic::add(strings_processed, &_strings_processed);
4696 Atomic::add(strings_removed, &_strings_removed);
4697 }
4698 if (_process_symbols) {
4699 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4700 Atomic::add(symbols_processed, &_symbols_processed);
4701 Atomic::add(symbols_removed, &_symbols_removed);
4702 }
4703 }
4704
4705 size_t strings_processed() const { return (size_t)_strings_processed; }
4706 size_t strings_removed() const { return (size_t)_strings_removed; }
4707
4708 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4709 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4710 };
4711
4712 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4713 private:
4714 static Monitor* _lock;
4715
4716 BoolObjectClosure* const _is_alive;
4717 const bool _unloading_occurred;
4718 const uint _num_workers;
4719
4720 // Variables used to claim nmethods.
4721 nmethod* _first_nmethod;
4722 volatile nmethod* _claimed_nmethod;
4723
4724 // The list of nmethods that need to be processed by the second pass.
4725 volatile nmethod* _postponed_list;
4726 volatile uint _num_entered_barrier;
4727
4728 public:
4729 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4730 _is_alive(is_alive),
4731 _unloading_occurred(unloading_occurred),
4732 _num_workers(num_workers),
4733 _first_nmethod(NULL),
4734 _claimed_nmethod(NULL),
4735 _postponed_list(NULL),
4736 _num_entered_barrier(0)
4737 {
4738 nmethod::increase_unloading_clock();
4739 // Get first alive nmethod
4740 NMethodIterator iter = NMethodIterator();
4741 if(iter.next_alive()) {
4742 _first_nmethod = iter.method();
4743 }
4744 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4745 }
4746
4747 ~G1CodeCacheUnloadingTask() {
4748 CodeCache::verify_clean_inline_caches();
4749
4750 CodeCache::set_needs_cache_clean(false);
4751 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4752
4753 CodeCache::verify_icholder_relocations();
4754 }
4755
4756 private:
4757 void add_to_postponed_list(nmethod* nm) {
4758 nmethod* old;
4759 do {
4760 old = (nmethod*)_postponed_list;
4761 nm->set_unloading_next(old);
4762 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4763 }
4764
4765 void clean_nmethod(nmethod* nm) {
4766 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4767
4768 if (postponed) {
4769 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4770 add_to_postponed_list(nm);
4771 }
4772
4773 // Mark that this thread has been cleaned/unloaded.
4774 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4775 nm->set_unloading_clock(nmethod::global_unloading_clock());
4776 }
4777
4778 void clean_nmethod_postponed(nmethod* nm) {
4779 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4780 }
4781
4782 static const int MaxClaimNmethods = 16;
4783
4784 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4785 nmethod* first;
4786 NMethodIterator last;
4787
4788 do {
4789 *num_claimed_nmethods = 0;
4790
4791 first = (nmethod*)_claimed_nmethod;
4792 last = NMethodIterator(first);
4793
4794 if (first != NULL) {
4795
4796 for (int i = 0; i < MaxClaimNmethods; i++) {
4797 if (!last.next_alive()) {
4798 break;
4799 }
4800 claimed_nmethods[i] = last.method();
4801 (*num_claimed_nmethods)++;
4802 }
4803 }
4804
4805 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4806 }
4807
4808 nmethod* claim_postponed_nmethod() {
4809 nmethod* claim;
4810 nmethod* next;
4811
4812 do {
4813 claim = (nmethod*)_postponed_list;
4814 if (claim == NULL) {
4815 return NULL;
4816 }
4817
4818 next = claim->unloading_next();
4819
4820 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4821
4822 return claim;
4823 }
4824
4825 public:
4826 // Mark that we're done with the first pass of nmethod cleaning.
4827 void barrier_mark(uint worker_id) {
4828 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4829 _num_entered_barrier++;
4830 if (_num_entered_barrier == _num_workers) {
4831 ml.notify_all();
4832 }
4833 }
4834
4835 // See if we have to wait for the other workers to
4836 // finish their first-pass nmethod cleaning work.
4837 void barrier_wait(uint worker_id) {
4838 if (_num_entered_barrier < _num_workers) {
4839 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4840 while (_num_entered_barrier < _num_workers) {
4841 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4842 }
4843 }
4844 }
4845
4846 // Cleaning and unloading of nmethods. Some work has to be postponed
4847 // to the second pass, when we know which nmethods survive.
4848 void work_first_pass(uint worker_id) {
4849 // The first nmethods is claimed by the first worker.
4850 if (worker_id == 0 && _first_nmethod != NULL) {
4851 clean_nmethod(_first_nmethod);
4852 _first_nmethod = NULL;
4853 }
4854
4855 int num_claimed_nmethods;
4856 nmethod* claimed_nmethods[MaxClaimNmethods];
4857
4858 while (true) {
4859 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4860
4861 if (num_claimed_nmethods == 0) {
4862 break;
4863 }
4864
4865 for (int i = 0; i < num_claimed_nmethods; i++) {
4866 clean_nmethod(claimed_nmethods[i]);
4867 }
4868 }
4869
4870 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4871 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4872 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4873 }
4874
4875 void work_second_pass(uint worker_id) {
4876 nmethod* nm;
4877 // Take care of postponed nmethods.
4878 while ((nm = claim_postponed_nmethod()) != NULL) {
4879 clean_nmethod_postponed(nm);
4880 }
4881 }
4882 };
4883
4884 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
4885
4886 class G1KlassCleaningTask : public StackObj {
4887 BoolObjectClosure* _is_alive;
4888 volatile jint _clean_klass_tree_claimed;
4889 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4890
4891 public:
4892 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4893 _is_alive(is_alive),
4894 _clean_klass_tree_claimed(0),
4895 _klass_iterator() {
4896 }
4897
4898 private:
4899 bool claim_clean_klass_tree_task() {
4900 if (_clean_klass_tree_claimed) {
4901 return false;
4902 }
4903
4904 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4905 }
4906
4907 InstanceKlass* claim_next_klass() {
4908 Klass* klass;
4909 do {
4910 klass =_klass_iterator.next_klass();
4911 } while (klass != NULL && !klass->oop_is_instance());
4912
4913 return (InstanceKlass*)klass;
4914 }
4915
4916 public:
4917
4918 void clean_klass(InstanceKlass* ik) {
4919 ik->clean_implementors_list(_is_alive);
4920 ik->clean_method_data(_is_alive);
4921
4922 // G1 specific cleanup work that has
4923 // been moved here to be done in parallel.
4924 ik->clean_dependent_nmethods();
4925 if (JvmtiExport::has_redefined_a_class()) {
4926 InstanceKlass::purge_previous_versions(ik);
4927 }
4928 }
4929
4930 void work() {
4931 ResourceMark rm;
4932
4933 // One worker will clean the subklass/sibling klass tree.
4934 if (claim_clean_klass_tree_task()) {
4935 Klass::clean_subklass_tree(_is_alive);
4936 }
4937
4938 // All workers will help cleaning the classes,
4939 InstanceKlass* klass;
4940 while ((klass = claim_next_klass()) != NULL) {
4941 clean_klass(klass);
4942 }
4943 }
4944 };
4945
4946 // To minimize the remark pause times, the tasks below are done in parallel.
4947 class G1ParallelCleaningTask : public AbstractGangTask {
4948 private:
4949 G1StringSymbolTableUnlinkTask _string_symbol_task;
4950 G1CodeCacheUnloadingTask _code_cache_task;
4951 G1KlassCleaningTask _klass_cleaning_task;
4952
4953 public:
4954 // The constructor is run in the VMThread.
4955 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4956 AbstractGangTask("Parallel Cleaning"),
4957 _string_symbol_task(is_alive, process_strings, process_symbols),
4958 _code_cache_task(num_workers, is_alive, unloading_occurred),
4959 _klass_cleaning_task(is_alive) {
4960 }
4961
4962 void pre_work_verification() {
4963 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4964 }
4965
4966 void post_work_verification() {
4967 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4968 }
4969
4970 // The parallel work done by all worker threads.
4971 void work(uint worker_id) {
4972 pre_work_verification();
4973
4974 // Do first pass of code cache cleaning.
4975 _code_cache_task.work_first_pass(worker_id);
4976
4977 // Let the threads mark that the first pass is done.
4978 _code_cache_task.barrier_mark(worker_id);
4979
4980 // Clean the Strings and Symbols.
4981 _string_symbol_task.work(worker_id);
4982
4983 // Wait for all workers to finish the first code cache cleaning pass.
4984 _code_cache_task.barrier_wait(worker_id);
4985
4986 // Do the second code cache cleaning work, which realize on
4987 // the liveness information gathered during the first pass.
4988 _code_cache_task.work_second_pass(worker_id);
4989
4990 // Clean all klasses that were not unloaded.
4991 _klass_cleaning_task.work();
4992
4993 post_work_verification();
4994 }
4995 };
4996
4997
4998 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4999 bool process_strings,
5000 bool process_symbols,
5001 bool class_unloading_occurred) {
5002 uint n_workers = workers()->active_workers();
5003
5004 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5005 n_workers, class_unloading_occurred);
5006 set_par_threads(n_workers);
5007 workers()->run_task(&g1_unlink_task);
5008 set_par_threads(0);
5009 }
5010
5011 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5012 bool process_strings, bool process_symbols) {
5013 {
5014 uint n_workers = _g1h->workers()->active_workers();
5015 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5016 set_par_threads(n_workers);
5017 workers()->run_task(&g1_unlink_task);
5018 set_par_threads(0);
5019 }
5020
5021 if (G1StringDedup::is_enabled()) {
5022 G1StringDedup::unlink(is_alive);
5023 }
5024 }
5025
5026 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5027 private:
5028 DirtyCardQueueSet* _queue;
5029 public:
5030 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5031
5032 virtual void work(uint worker_id) {
5033 double start_time = os::elapsedTime();
5034
5035 RedirtyLoggedCardTableEntryClosure cl;
5036 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5037
5038 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5039 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5040 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5041 }
5042 };
5043
5044 void G1CollectedHeap::redirty_logged_cards() {
5045 double redirty_logged_cards_start = os::elapsedTime();
5046
5047 uint n_workers = _g1h->workers()->active_workers();
5048
5049 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5050 dirty_card_queue_set().reset_for_par_iteration();
5051 set_par_threads(n_workers);
5052 workers()->run_task(&redirty_task);
5053 set_par_threads(0);
5054
5055 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5056 dcq.merge_bufferlists(&dirty_card_queue_set());
5057 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5058
5059 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5060 }
5061
5062 // Weak Reference Processing support
5063
5064 // An always "is_alive" closure that is used to preserve referents.
5065 // If the object is non-null then it's alive. Used in the preservation
5066 // of referent objects that are pointed to by reference objects
5067 // discovered by the CM ref processor.
5068 class G1AlwaysAliveClosure: public BoolObjectClosure {
5069 G1CollectedHeap* _g1;
5070 public:
5071 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5072 bool do_object_b(oop p) {
5073 if (p != NULL) {
5074 return true;
5075 }
5076 return false;
5077 }
5078 };
5079
5080 bool G1STWIsAliveClosure::do_object_b(oop p) {
5081 // An object is reachable if it is outside the collection set,
5082 // or is inside and copied.
5083 return !_g1->obj_in_cs(p) || p->is_forwarded();
5084 }
5085
5086 // Non Copying Keep Alive closure
5087 class G1KeepAliveClosure: public OopClosure {
5088 G1CollectedHeap* _g1;
5089 public:
5090 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5091 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5092 void do_oop(oop* p) {
5093 oop obj = *p;
5094 assert(obj != NULL, "the caller should have filtered out NULL values");
5095
5096 const InCSetState cset_state = _g1->in_cset_state(obj);
5097 if (!cset_state.is_in_cset_or_humongous()) {
5098 return;
5099 }
5100 if (cset_state.is_in_cset()) {
5101 assert( obj->is_forwarded(), "invariant" );
5102 *p = obj->forwardee();
5103 } else {
5104 assert(!obj->is_forwarded(), "invariant" );
5105 assert(cset_state.is_humongous(),
5106 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5107 _g1->set_humongous_is_live(obj);
5108 }
5109 }
5110 };
5111
5112 // Copying Keep Alive closure - can be called from both
5113 // serial and parallel code as long as different worker
5114 // threads utilize different G1ParScanThreadState instances
5115 // and different queues.
5116
5117 class G1CopyingKeepAliveClosure: public OopClosure {
5118 G1CollectedHeap* _g1h;
5119 OopClosure* _copy_non_heap_obj_cl;
5120 G1ParScanThreadState* _par_scan_state;
5121
5122 public:
5123 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5124 OopClosure* non_heap_obj_cl,
5125 G1ParScanThreadState* pss):
5126 _g1h(g1h),
5127 _copy_non_heap_obj_cl(non_heap_obj_cl),
5128 _par_scan_state(pss)
5129 {}
5130
5131 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5132 virtual void do_oop( oop* p) { do_oop_work(p); }
5133
5134 template <class T> void do_oop_work(T* p) {
5135 oop obj = oopDesc::load_decode_heap_oop(p);
5136
5137 if (_g1h->is_in_cset_or_humongous(obj)) {
5138 // If the referent object has been forwarded (either copied
5139 // to a new location or to itself in the event of an
5140 // evacuation failure) then we need to update the reference
5141 // field and, if both reference and referent are in the G1
5142 // heap, update the RSet for the referent.
5143 //
5144 // If the referent has not been forwarded then we have to keep
5145 // it alive by policy. Therefore we have copy the referent.
5146 //
5147 // If the reference field is in the G1 heap then we can push
5148 // on the PSS queue. When the queue is drained (after each
5149 // phase of reference processing) the object and it's followers
5150 // will be copied, the reference field set to point to the
5151 // new location, and the RSet updated. Otherwise we need to
5152 // use the the non-heap or metadata closures directly to copy
5153 // the referent object and update the pointer, while avoiding
5154 // updating the RSet.
5155
5156 if (_g1h->is_in_g1_reserved(p)) {
5157 _par_scan_state->push_on_queue(p);
5158 } else {
5159 assert(!Metaspace::contains((const void*)p),
5160 err_msg("Unexpectedly found a pointer from metadata: "
5161 PTR_FORMAT, p));
5162 _copy_non_heap_obj_cl->do_oop(p);
5163 }
5164 }
5165 }
5166 };
5167
5168 // Serial drain queue closure. Called as the 'complete_gc'
5169 // closure for each discovered list in some of the
5170 // reference processing phases.
5171
5172 class G1STWDrainQueueClosure: public VoidClosure {
5173 protected:
5174 G1CollectedHeap* _g1h;
5175 G1ParScanThreadState* _par_scan_state;
5176
5177 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5178
5179 public:
5180 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5181 _g1h(g1h),
5182 _par_scan_state(pss)
5183 { }
5184
5185 void do_void() {
5186 G1ParScanThreadState* const pss = par_scan_state();
5187 pss->trim_queue();
5188 }
5189 };
5190
5191 // Parallel Reference Processing closures
5192
5193 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5194 // processing during G1 evacuation pauses.
5195
5196 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5197 private:
5198 G1CollectedHeap* _g1h;
5199 RefToScanQueueSet* _queues;
5200 FlexibleWorkGang* _workers;
5201 int _active_workers;
5202
5203 public:
5204 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5205 FlexibleWorkGang* workers,
5206 RefToScanQueueSet *task_queues,
5207 int n_workers) :
5208 _g1h(g1h),
5209 _queues(task_queues),
5210 _workers(workers),
5211 _active_workers(n_workers)
5212 {
5213 assert(n_workers > 0, "shouldn't call this otherwise");
5214 }
5215
5216 // Executes the given task using concurrent marking worker threads.
5217 virtual void execute(ProcessTask& task);
5218 virtual void execute(EnqueueTask& task);
5219 };
5220
5221 // Gang task for possibly parallel reference processing
5222
5223 class G1STWRefProcTaskProxy: public AbstractGangTask {
5224 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5225 ProcessTask& _proc_task;
5226 G1CollectedHeap* _g1h;
5227 RefToScanQueueSet *_task_queues;
5228 ParallelTaskTerminator* _terminator;
5229
5230 public:
5231 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5232 G1CollectedHeap* g1h,
5233 RefToScanQueueSet *task_queues,
5234 ParallelTaskTerminator* terminator) :
5235 AbstractGangTask("Process reference objects in parallel"),
5236 _proc_task(proc_task),
5237 _g1h(g1h),
5238 _task_queues(task_queues),
5239 _terminator(terminator)
5240 {}
5241
5242 virtual void work(uint worker_id) {
5243 // The reference processing task executed by a single worker.
5244 ResourceMark rm;
5245 HandleMark hm;
5246
5247 G1STWIsAliveClosure is_alive(_g1h);
5248
5249 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5250 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5251
5252 pss.set_evac_failure_closure(&evac_failure_cl);
5253
5254 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5255
5256 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5257
5258 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5259
5260 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5261 // We also need to mark copied objects.
5262 copy_non_heap_cl = ©_mark_non_heap_cl;
5263 }
5264
5265 // Keep alive closure.
5266 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5267
5268 // Complete GC closure
5269 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5270
5271 // Call the reference processing task's work routine.
5272 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5273
5274 // Note we cannot assert that the refs array is empty here as not all
5275 // of the processing tasks (specifically phase2 - pp2_work) execute
5276 // the complete_gc closure (which ordinarily would drain the queue) so
5277 // the queue may not be empty.
5278 }
5279 };
5280
5281 // Driver routine for parallel reference processing.
5282 // Creates an instance of the ref processing gang
5283 // task and has the worker threads execute it.
5284 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5285 assert(_workers != NULL, "Need parallel worker threads.");
5286
5287 ParallelTaskTerminator terminator(_active_workers, _queues);
5288 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5289
5290 _g1h->set_par_threads(_active_workers);
5291 _workers->run_task(&proc_task_proxy);
5292 _g1h->set_par_threads(0);
5293 }
5294
5295 // Gang task for parallel reference enqueueing.
5296
5297 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5298 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5299 EnqueueTask& _enq_task;
5300
5301 public:
5302 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5303 AbstractGangTask("Enqueue reference objects in parallel"),
5304 _enq_task(enq_task)
5305 { }
5306
5307 virtual void work(uint worker_id) {
5308 _enq_task.work(worker_id);
5309 }
5310 };
5311
5312 // Driver routine for parallel reference enqueueing.
5313 // Creates an instance of the ref enqueueing gang
5314 // task and has the worker threads execute it.
5315
5316 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5317 assert(_workers != NULL, "Need parallel worker threads.");
5318
5319 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5320
5321 _g1h->set_par_threads(_active_workers);
5322 _workers->run_task(&enq_task_proxy);
5323 _g1h->set_par_threads(0);
5324 }
5325
5326 // End of weak reference support closures
5327
5328 // Abstract task used to preserve (i.e. copy) any referent objects
5329 // that are in the collection set and are pointed to by reference
5330 // objects discovered by the CM ref processor.
5331
5332 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5333 protected:
5334 G1CollectedHeap* _g1h;
5335 RefToScanQueueSet *_queues;
5336 ParallelTaskTerminator _terminator;
5337 uint _n_workers;
5338
5339 public:
5340 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5341 AbstractGangTask("ParPreserveCMReferents"),
5342 _g1h(g1h),
5343 _queues(task_queues),
5344 _terminator(workers, _queues),
5345 _n_workers(workers)
5346 { }
5347
5348 void work(uint worker_id) {
5349 ResourceMark rm;
5350 HandleMark hm;
5351
5352 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5353 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5354
5355 pss.set_evac_failure_closure(&evac_failure_cl);
5356
5357 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5358
5359 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5360
5361 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5362
5363 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5364
5365 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5366 // We also need to mark copied objects.
5367 copy_non_heap_cl = ©_mark_non_heap_cl;
5368 }
5369
5370 // Is alive closure
5371 G1AlwaysAliveClosure always_alive(_g1h);
5372
5373 // Copying keep alive closure. Applied to referent objects that need
5374 // to be copied.
5375 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5376
5377 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5378
5379 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5380 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5381
5382 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5383 // So this must be true - but assert just in case someone decides to
5384 // change the worker ids.
5385 assert(0 <= worker_id && worker_id < limit, "sanity");
5386 assert(!rp->discovery_is_atomic(), "check this code");
5387
5388 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5389 for (uint idx = worker_id; idx < limit; idx += stride) {
5390 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5391
5392 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5393 while (iter.has_next()) {
5394 // Since discovery is not atomic for the CM ref processor, we
5395 // can see some null referent objects.
5396 iter.load_ptrs(DEBUG_ONLY(true));
5397 oop ref = iter.obj();
5398
5399 // This will filter nulls.
5400 if (iter.is_referent_alive()) {
5401 iter.make_referent_alive();
5402 }
5403 iter.move_to_next();
5404 }
5405 }
5406
5407 // Drain the queue - which may cause stealing
5408 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5409 drain_queue.do_void();
5410 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5411 assert(pss.queue_is_empty(), "should be");
5412 }
5413 };
5414
5415 // Weak Reference processing during an evacuation pause (part 1).
5416 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5417 double ref_proc_start = os::elapsedTime();
5418
5419 ReferenceProcessor* rp = _ref_processor_stw;
5420 assert(rp->discovery_enabled(), "should have been enabled");
5421
5422 // Any reference objects, in the collection set, that were 'discovered'
5423 // by the CM ref processor should have already been copied (either by
5424 // applying the external root copy closure to the discovered lists, or
5425 // by following an RSet entry).
5426 //
5427 // But some of the referents, that are in the collection set, that these
5428 // reference objects point to may not have been copied: the STW ref
5429 // processor would have seen that the reference object had already
5430 // been 'discovered' and would have skipped discovering the reference,
5431 // but would not have treated the reference object as a regular oop.
5432 // As a result the copy closure would not have been applied to the
5433 // referent object.
5434 //
5435 // We need to explicitly copy these referent objects - the references
5436 // will be processed at the end of remarking.
5437 //
5438 // We also need to do this copying before we process the reference
5439 // objects discovered by the STW ref processor in case one of these
5440 // referents points to another object which is also referenced by an
5441 // object discovered by the STW ref processor.
5442
5443 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5444
5445 set_par_threads(no_of_gc_workers);
5446 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5447 no_of_gc_workers,
5448 _task_queues);
5449
5450 workers()->run_task(&keep_cm_referents);
5451
5452 set_par_threads(0);
5453
5454 // Closure to test whether a referent is alive.
5455 G1STWIsAliveClosure is_alive(this);
5456
5457 // Even when parallel reference processing is enabled, the processing
5458 // of JNI refs is serial and performed serially by the current thread
5459 // rather than by a worker. The following PSS will be used for processing
5460 // JNI refs.
5461
5462 // Use only a single queue for this PSS.
5463 G1ParScanThreadState pss(this, 0, NULL);
5464
5465 // We do not embed a reference processor in the copying/scanning
5466 // closures while we're actually processing the discovered
5467 // reference objects.
5468 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5469
5470 pss.set_evac_failure_closure(&evac_failure_cl);
5471
5472 assert(pss.queue_is_empty(), "pre-condition");
5473
5474 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5475
5476 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5477
5478 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5479
5480 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5481 // We also need to mark copied objects.
5482 copy_non_heap_cl = ©_mark_non_heap_cl;
5483 }
5484
5485 // Keep alive closure.
5486 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5487
5488 // Serial Complete GC closure
5489 G1STWDrainQueueClosure drain_queue(this, &pss);
5490
5491 // Setup the soft refs policy...
5492 rp->setup_policy(false);
5493
5494 ReferenceProcessorStats stats;
5495 if (!rp->processing_is_mt()) {
5496 // Serial reference processing...
5497 stats = rp->process_discovered_references(&is_alive,
5498 &keep_alive,
5499 &drain_queue,
5500 NULL,
5501 _gc_timer_stw,
5502 _gc_tracer_stw->gc_id());
5503 } else {
5504 // Parallel reference processing
5505 assert(rp->num_q() == no_of_gc_workers, "sanity");
5506 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5507
5508 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5509 stats = rp->process_discovered_references(&is_alive,
5510 &keep_alive,
5511 &drain_queue,
5512 &par_task_executor,
5513 _gc_timer_stw,
5514 _gc_tracer_stw->gc_id());
5515 }
5516
5517 _gc_tracer_stw->report_gc_reference_stats(stats);
5518
5519 // We have completed copying any necessary live referent objects.
5520 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5521
5522 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5523 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5524 }
5525
5526 // Weak Reference processing during an evacuation pause (part 2).
5527 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5528 double ref_enq_start = os::elapsedTime();
5529
5530 ReferenceProcessor* rp = _ref_processor_stw;
5531 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5532
5533 // Now enqueue any remaining on the discovered lists on to
5534 // the pending list.
5535 if (!rp->processing_is_mt()) {
5536 // Serial reference processing...
5537 rp->enqueue_discovered_references();
5538 } else {
5539 // Parallel reference enqueueing
5540
5541 assert(no_of_gc_workers == workers()->active_workers(),
5542 "Need to reset active workers");
5543 assert(rp->num_q() == no_of_gc_workers, "sanity");
5544 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5545
5546 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5547 rp->enqueue_discovered_references(&par_task_executor);
5548 }
5549
5550 rp->verify_no_references_recorded();
5551 assert(!rp->discovery_enabled(), "should have been disabled");
5552
5553 // FIXME
5554 // CM's reference processing also cleans up the string and symbol tables.
5555 // Should we do that here also? We could, but it is a serial operation
5556 // and could significantly increase the pause time.
5557
5558 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5559 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5560 }
5561
5562 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5563 _expand_heap_after_alloc_failure = true;
5564 _evacuation_failed = false;
5565
5566 // Should G1EvacuationFailureALot be in effect for this GC?
5567 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5568
5569 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5570
5571 // Disable the hot card cache.
5572 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5573 hot_card_cache->reset_hot_cache_claimed_index();
5574 hot_card_cache->set_use_cache(false);
5575
5576 uint n_workers;
5577 n_workers =
5578 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5579 workers()->active_workers(),
5580 Threads::number_of_non_daemon_threads());
5581 assert(UseDynamicNumberOfGCThreads ||
5582 n_workers == workers()->total_workers(),
5583 "If not dynamic should be using all the workers");
5584 workers()->set_active_workers(n_workers);
5585 set_par_threads(n_workers);
5586
5587 G1ParTask g1_par_task(this, _task_queues);
5588
5589 init_for_evac_failure(NULL);
5590
5591 rem_set()->prepare_for_younger_refs_iterate(true);
5592
5593 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5594 double start_par_time_sec = os::elapsedTime();
5595 double end_par_time_sec;
5596
5597 {
5598 StrongRootsScope srs(this);
5599 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5600 if (g1_policy()->during_initial_mark_pause()) {
5601 ClassLoaderDataGraph::clear_claimed_marks();
5602 }
5603
5604 // The individual threads will set their evac-failure closures.
5605 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5606 // These tasks use ShareHeap::_process_strong_tasks
5607 assert(UseDynamicNumberOfGCThreads ||
5608 workers()->active_workers() == workers()->total_workers(),
5609 "If not dynamic should be using all the workers");
5610 workers()->run_task(&g1_par_task);
5611 end_par_time_sec = os::elapsedTime();
5612
5613 // Closing the inner scope will execute the destructor
5614 // for the StrongRootsScope object. We record the current
5615 // elapsed time before closing the scope so that time
5616 // taken for the SRS destructor is NOT included in the
5617 // reported parallel time.
5618 }
5619
5620 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5621 g1_policy()->phase_times()->record_par_time(par_time_ms);
5622
5623 double code_root_fixup_time_ms =
5624 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5625 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5626
5627 set_par_threads(0);
5628
5629 // Process any discovered reference objects - we have
5630 // to do this _before_ we retire the GC alloc regions
5631 // as we may have to copy some 'reachable' referent
5632 // objects (and their reachable sub-graphs) that were
5633 // not copied during the pause.
5634 process_discovered_references(n_workers);
5635
5636 if (G1StringDedup::is_enabled()) {
5637 G1STWIsAliveClosure is_alive(this);
5638 G1KeepAliveClosure keep_alive(this);
5639 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5640 }
5641
5642 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5643 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5644
5645 // Reset and re-enable the hot card cache.
5646 // Note the counts for the cards in the regions in the
5647 // collection set are reset when the collection set is freed.
5648 hot_card_cache->reset_hot_cache();
5649 hot_card_cache->set_use_cache(true);
5650
5651 purge_code_root_memory();
5652
5653 finalize_for_evac_failure();
5654
5655 if (evacuation_failed()) {
5656 remove_self_forwarding_pointers();
5657
5658 // Reset the G1EvacuationFailureALot counters and flags
5659 // Note: the values are reset only when an actual
5660 // evacuation failure occurs.
5661 NOT_PRODUCT(reset_evacuation_should_fail();)
5662 }
5663
5664 // Enqueue any remaining references remaining on the STW
5665 // reference processor's discovered lists. We need to do
5666 // this after the card table is cleaned (and verified) as
5667 // the act of enqueueing entries on to the pending list
5668 // will log these updates (and dirty their associated
5669 // cards). We need these updates logged to update any
5670 // RSets.
5671 enqueue_discovered_references(n_workers);
5672
5673 redirty_logged_cards();
5674 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5675 }
5676
5677 void G1CollectedHeap::free_region(HeapRegion* hr,
5678 FreeRegionList* free_list,
5679 bool par,
5680 bool locked) {
5681 assert(!hr->is_free(), "the region should not be free");
5682 assert(!hr->is_empty(), "the region should not be empty");
5683 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5684 assert(free_list != NULL, "pre-condition");
5685
5686 if (G1VerifyBitmaps) {
5687 MemRegion mr(hr->bottom(), hr->end());
5688 concurrent_mark()->clearRangePrevBitmap(mr);
5689 }
5690
5691 // Clear the card counts for this region.
5692 // Note: we only need to do this if the region is not young
5693 // (since we don't refine cards in young regions).
5694 if (!hr->is_young()) {
5695 _cg1r->hot_card_cache()->reset_card_counts(hr);
5696 }
5697 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5698 free_list->add_ordered(hr);
5699 }
5700
5701 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5702 FreeRegionList* free_list,
5703 bool par) {
5704 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5705 assert(free_list != NULL, "pre-condition");
5706
5707 size_t hr_capacity = hr->capacity();
5708 // We need to read this before we make the region non-humongous,
5709 // otherwise the information will be gone.
5710 uint last_index = hr->last_hc_index();
5711 hr->clear_humongous();
5712 free_region(hr, free_list, par);
5713
5714 uint i = hr->hrm_index() + 1;
5715 while (i < last_index) {
5716 HeapRegion* curr_hr = region_at(i);
5717 assert(curr_hr->is_continues_humongous(), "invariant");
5718 curr_hr->clear_humongous();
5719 free_region(curr_hr, free_list, par);
5720 i += 1;
5721 }
5722 }
5723
5724 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5725 const HeapRegionSetCount& humongous_regions_removed) {
5726 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5727 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5728 _old_set.bulk_remove(old_regions_removed);
5729 _humongous_set.bulk_remove(humongous_regions_removed);
5730 }
5731
5732 }
5733
5734 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5735 assert(list != NULL, "list can't be null");
5736 if (!list->is_empty()) {
5737 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5738 _hrm.insert_list_into_free_list(list);
5739 }
5740 }
5741
5742 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5743 _allocator->decrease_used(bytes);
5744 }
5745
5746 class G1ParCleanupCTTask : public AbstractGangTask {
5747 G1SATBCardTableModRefBS* _ct_bs;
5748 G1CollectedHeap* _g1h;
5749 HeapRegion* volatile _su_head;
5750 public:
5751 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5752 G1CollectedHeap* g1h) :
5753 AbstractGangTask("G1 Par Cleanup CT Task"),
5754 _ct_bs(ct_bs), _g1h(g1h) { }
5755
5756 void work(uint worker_id) {
5757 HeapRegion* r;
5758 while (r = _g1h->pop_dirty_cards_region()) {
5759 clear_cards(r);
5760 }
5761 }
5762
5763 void clear_cards(HeapRegion* r) {
5764 // Cards of the survivors should have already been dirtied.
5765 if (!r->is_survivor()) {
5766 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5767 }
5768 }
5769 };
5770
5771 #ifndef PRODUCT
5772 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5773 G1CollectedHeap* _g1h;
5774 G1SATBCardTableModRefBS* _ct_bs;
5775 public:
5776 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5777 : _g1h(g1h), _ct_bs(ct_bs) { }
5778 virtual bool doHeapRegion(HeapRegion* r) {
5779 if (r->is_survivor()) {
5780 _g1h->verify_dirty_region(r);
5781 } else {
5782 _g1h->verify_not_dirty_region(r);
5783 }
5784 return false;
5785 }
5786 };
5787
5788 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5789 // All of the region should be clean.
5790 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5791 MemRegion mr(hr->bottom(), hr->end());
5792 ct_bs->verify_not_dirty_region(mr);
5793 }
5794
5795 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5796 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5797 // dirty allocated blocks as they allocate them. The thread that
5798 // retires each region and replaces it with a new one will do a
5799 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5800 // not dirty that area (one less thing to have to do while holding
5801 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5802 // is dirty.
5803 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5804 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5805 if (hr->is_young()) {
5806 ct_bs->verify_g1_young_region(mr);
5807 } else {
5808 ct_bs->verify_dirty_region(mr);
5809 }
5810 }
5811
5812 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5813 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5814 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5815 verify_dirty_region(hr);
5816 }
5817 }
5818
5819 void G1CollectedHeap::verify_dirty_young_regions() {
5820 verify_dirty_young_list(_young_list->first_region());
5821 }
5822
5823 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5824 HeapWord* tams, HeapWord* end) {
5825 guarantee(tams <= end,
5826 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5827 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5828 if (result < end) {
5829 gclog_or_tty->cr();
5830 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5831 bitmap_name, result);
5832 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5833 bitmap_name, tams, end);
5834 return false;
5835 }
5836 return true;
5837 }
5838
5839 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5840 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5841 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5842
5843 HeapWord* bottom = hr->bottom();
5844 HeapWord* ptams = hr->prev_top_at_mark_start();
5845 HeapWord* ntams = hr->next_top_at_mark_start();
5846 HeapWord* end = hr->end();
5847
5848 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5849
5850 bool res_n = true;
5851 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5852 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5853 // if we happen to be in that state.
5854 if (mark_in_progress() || !_cmThread->in_progress()) {
5855 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5856 }
5857 if (!res_p || !res_n) {
5858 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5859 HR_FORMAT_PARAMS(hr));
5860 gclog_or_tty->print_cr("#### Caller: %s", caller);
5861 return false;
5862 }
5863 return true;
5864 }
5865
5866 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5867 if (!G1VerifyBitmaps) return;
5868
5869 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5870 }
5871
5872 class G1VerifyBitmapClosure : public HeapRegionClosure {
5873 private:
5874 const char* _caller;
5875 G1CollectedHeap* _g1h;
5876 bool _failures;
5877
5878 public:
5879 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5880 _caller(caller), _g1h(g1h), _failures(false) { }
5881
5882 bool failures() { return _failures; }
5883
5884 virtual bool doHeapRegion(HeapRegion* hr) {
5885 if (hr->is_continues_humongous()) return false;
5886
5887 bool result = _g1h->verify_bitmaps(_caller, hr);
5888 if (!result) {
5889 _failures = true;
5890 }
5891 return false;
5892 }
5893 };
5894
5895 void G1CollectedHeap::check_bitmaps(const char* caller) {
5896 if (!G1VerifyBitmaps) return;
5897
5898 G1VerifyBitmapClosure cl(caller, this);
5899 heap_region_iterate(&cl);
5900 guarantee(!cl.failures(), "bitmap verification");
5901 }
5902
5903 bool G1CollectedHeap::check_cset_fast_test() {
5904 bool failures = false;
5905 for (uint i = 0; i < _hrm.length(); i += 1) {
5906 HeapRegion* hr = _hrm.at(i);
5907 InCSetState cset_state = (InCSetState) _in_cset_fast_test.get_by_index((uint) i);
5908 if (hr->is_humongous()) {
5909 if (hr->in_collection_set()) {
5910 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5911 failures = true;
5912 break;
5913 }
5914 if (cset_state.is_in_cset()) {
5915 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5916 failures = true;
5917 break;
5918 }
5919 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5920 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5921 failures = true;
5922 break;
5923 }
5924 } else {
5925 if (cset_state.is_humongous()) {
5926 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5927 failures = true;
5928 break;
5929 }
5930 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5931 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5932 hr->in_collection_set(), cset_state.value(), i);
5933 failures = true;
5934 break;
5935 }
5936 if (cset_state.is_in_cset()) {
5937 if (hr->is_young() != (cset_state.is_young())) {
5938 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5939 hr->is_young(), cset_state.value(), i);
5940 failures = true;
5941 break;
5942 }
5943 if (hr->is_old() != (cset_state.is_old())) {
5944 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5945 hr->is_old(), cset_state.value(), i);
5946 failures = true;
5947 break;
5948 }
5949 }
5950 }
5951 }
5952 return !failures;
5953 }
5954 #endif // PRODUCT
5955
5956 void G1CollectedHeap::cleanUpCardTable() {
5957 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5958 double start = os::elapsedTime();
5959
5960 {
5961 // Iterate over the dirty cards region list.
5962 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5963
5964 set_par_threads();
5965 workers()->run_task(&cleanup_task);
5966 set_par_threads(0);
5967 #ifndef PRODUCT
5968 if (G1VerifyCTCleanup || VerifyAfterGC) {
5969 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5970 heap_region_iterate(&cleanup_verifier);
5971 }
5972 #endif
5973 }
5974
5975 double elapsed = os::elapsedTime() - start;
5976 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5977 }
5978
5979 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5980 size_t pre_used = 0;
5981 FreeRegionList local_free_list("Local List for CSet Freeing");
5982
5983 double young_time_ms = 0.0;
5984 double non_young_time_ms = 0.0;
5985
5986 // Since the collection set is a superset of the the young list,
5987 // all we need to do to clear the young list is clear its
5988 // head and length, and unlink any young regions in the code below
5989 _young_list->clear();
5990
5991 G1CollectorPolicy* policy = g1_policy();
5992
5993 double start_sec = os::elapsedTime();
5994 bool non_young = true;
5995
5996 HeapRegion* cur = cs_head;
5997 int age_bound = -1;
5998 size_t rs_lengths = 0;
5999
6000 while (cur != NULL) {
6001 assert(!is_on_master_free_list(cur), "sanity");
6002 if (non_young) {
6003 if (cur->is_young()) {
6004 double end_sec = os::elapsedTime();
6005 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6006 non_young_time_ms += elapsed_ms;
6007
6008 start_sec = os::elapsedTime();
6009 non_young = false;
6010 }
6011 } else {
6012 if (!cur->is_young()) {
6013 double end_sec = os::elapsedTime();
6014 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6015 young_time_ms += elapsed_ms;
6016
6017 start_sec = os::elapsedTime();
6018 non_young = true;
6019 }
6020 }
6021
6022 rs_lengths += cur->rem_set()->occupied_locked();
6023
6024 HeapRegion* next = cur->next_in_collection_set();
6025 assert(cur->in_collection_set(), "bad CS");
6026 cur->set_next_in_collection_set(NULL);
6027 cur->set_in_collection_set(false);
6028
6029 if (cur->is_young()) {
6030 int index = cur->young_index_in_cset();
6031 assert(index != -1, "invariant");
6032 assert((uint) index < policy->young_cset_region_length(), "invariant");
6033 size_t words_survived = _surviving_young_words[index];
6034 cur->record_surv_words_in_group(words_survived);
6035
6036 // At this point the we have 'popped' cur from the collection set
6037 // (linked via next_in_collection_set()) but it is still in the
6038 // young list (linked via next_young_region()). Clear the
6039 // _next_young_region field.
6040 cur->set_next_young_region(NULL);
6041 } else {
6042 int index = cur->young_index_in_cset();
6043 assert(index == -1, "invariant");
6044 }
6045
6046 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6047 (!cur->is_young() && cur->young_index_in_cset() == -1),
6048 "invariant" );
6049
6050 if (!cur->evacuation_failed()) {
6051 MemRegion used_mr = cur->used_region();
6052
6053 // And the region is empty.
6054 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6055 pre_used += cur->used();
6056 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6057 } else {
6058 cur->uninstall_surv_rate_group();
6059 if (cur->is_young()) {
6060 cur->set_young_index_in_cset(-1);
6061 }
6062 cur->set_evacuation_failed(false);
6063 // The region is now considered to be old.
6064 cur->set_old();
6065 _old_set.add(cur);
6066 evacuation_info.increment_collectionset_used_after(cur->used());
6067 }
6068 cur = next;
6069 }
6070
6071 evacuation_info.set_regions_freed(local_free_list.length());
6072 policy->record_max_rs_lengths(rs_lengths);
6073 policy->cset_regions_freed();
6074
6075 double end_sec = os::elapsedTime();
6076 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6077
6078 if (non_young) {
6079 non_young_time_ms += elapsed_ms;
6080 } else {
6081 young_time_ms += elapsed_ms;
6082 }
6083
6084 prepend_to_freelist(&local_free_list);
6085 decrement_summary_bytes(pre_used);
6086 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6087 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6088 }
6089
6090 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6091 private:
6092 FreeRegionList* _free_region_list;
6093 HeapRegionSet* _proxy_set;
6094 HeapRegionSetCount _humongous_regions_removed;
6095 size_t _freed_bytes;
6096 public:
6097
6098 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6099 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6100 }
6101
6102 virtual bool doHeapRegion(HeapRegion* r) {
6103 if (!r->is_starts_humongous()) {
6104 return false;
6105 }
6106
6107 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6108
6109 oop obj = (oop)r->bottom();
6110 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6111
6112 // The following checks whether the humongous object is live are sufficient.
6113 // The main additional check (in addition to having a reference from the roots
6114 // or the young gen) is whether the humongous object has a remembered set entry.
6115 //
6116 // A humongous object cannot be live if there is no remembered set for it
6117 // because:
6118 // - there can be no references from within humongous starts regions referencing
6119 // the object because we never allocate other objects into them.
6120 // (I.e. there are no intra-region references that may be missed by the
6121 // remembered set)
6122 // - as soon there is a remembered set entry to the humongous starts region
6123 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6124 // until the end of a concurrent mark.
6125 //
6126 // It is not required to check whether the object has been found dead by marking
6127 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6128 // all objects allocated during that time are considered live.
6129 // SATB marking is even more conservative than the remembered set.
6130 // So if at this point in the collection there is no remembered set entry,
6131 // nobody has a reference to it.
6132 // At the start of collection we flush all refinement logs, and remembered sets
6133 // are completely up-to-date wrt to references to the humongous object.
6134 //
6135 // Other implementation considerations:
6136 // - never consider object arrays: while they are a valid target, they have not
6137 // been observed to be used as temporary objects.
6138 // - they would also pose considerable effort for cleaning up the the remembered
6139 // sets.
6140 // While this cleanup is not strictly necessary to be done (or done instantly),
6141 // given that their occurrence is very low, this saves us this additional
6142 // complexity.
6143 uint region_idx = r->hrm_index();
6144 if (g1h->humongous_is_live(region_idx) ||
6145 g1h->humongous_region_is_always_live(region_idx)) {
6146
6147 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6148 gclog_or_tty->print_cr("Live humongous %d region %d size "SIZE_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6149 r->is_humongous(),
6150 region_idx,
6151 obj->size()*HeapWordSize,
6152 r->rem_set()->occupied(),
6153 r->rem_set()->strong_code_roots_list_length(),
6154 next_bitmap->isMarked(r->bottom()),
6155 g1h->humongous_is_live(region_idx),
6156 obj->is_objArray()
6157 );
6158 }
6159
6160 return false;
6161 }
6162
6163 guarantee(!obj->is_objArray(),
6164 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6165 r->bottom()));
6166
6167 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6168 gclog_or_tty->print_cr("Reclaim humongous region %d size "SIZE_FORMAT" start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6169 r->is_humongous(),
6170 obj->size()*HeapWordSize,
6171 r->bottom(),
6172 region_idx,
6173 r->region_num(),
6174 r->rem_set()->occupied(),
6175 r->rem_set()->strong_code_roots_list_length(),
6176 next_bitmap->isMarked(r->bottom()),
6177 g1h->humongous_is_live(region_idx),
6178 obj->is_objArray()
6179 );
6180 }
6181 // Need to clear mark bit of the humongous object if already set.
6182 if (next_bitmap->isMarked(r->bottom())) {
6183 next_bitmap->clear(r->bottom());
6184 }
6185 _freed_bytes += r->used();
6186 r->set_containing_set(NULL);
6187 _humongous_regions_removed.increment(1u, r->capacity());
6188 g1h->free_humongous_region(r, _free_region_list, false);
6189
6190 return false;
6191 }
6192
6193 HeapRegionSetCount& humongous_free_count() {
6194 return _humongous_regions_removed;
6195 }
6196
6197 size_t bytes_freed() const {
6198 return _freed_bytes;
6199 }
6200
6201 size_t humongous_reclaimed() const {
6202 return _humongous_regions_removed.length();
6203 }
6204 };
6205
6206 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6207 assert_at_safepoint(true);
6208
6209 if (!G1ReclaimDeadHumongousObjectsAtYoungGC ||
6210 (!_has_humongous_reclaim_candidates && !G1TraceReclaimDeadHumongousObjectsAtYoungGC)) {
6211 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6212 return;
6213 }
6214
6215 double start_time = os::elapsedTime();
6216
6217 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6218
6219 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6220 heap_region_iterate(&cl);
6221
6222 HeapRegionSetCount empty_set;
6223 remove_from_old_sets(empty_set, cl.humongous_free_count());
6224
6225 G1HRPrinter* hr_printer = _g1h->hr_printer();
6226 if (hr_printer->is_active()) {
6227 FreeRegionListIterator iter(&local_cleanup_list);
6228 while (iter.more_available()) {
6229 HeapRegion* hr = iter.get_next();
6230 hr_printer->cleanup(hr);
6231 }
6232 }
6233
6234 prepend_to_freelist(&local_cleanup_list);
6235 decrement_summary_bytes(cl.bytes_freed());
6236
6237 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6238 cl.humongous_reclaimed());
6239 }
6240
6241 // This routine is similar to the above but does not record
6242 // any policy statistics or update free lists; we are abandoning
6243 // the current incremental collection set in preparation of a
6244 // full collection. After the full GC we will start to build up
6245 // the incremental collection set again.
6246 // This is only called when we're doing a full collection
6247 // and is immediately followed by the tearing down of the young list.
6248
6249 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6250 HeapRegion* cur = cs_head;
6251
6252 while (cur != NULL) {
6253 HeapRegion* next = cur->next_in_collection_set();
6254 assert(cur->in_collection_set(), "bad CS");
6255 cur->set_next_in_collection_set(NULL);
6256 cur->set_in_collection_set(false);
6257 cur->set_young_index_in_cset(-1);
6258 cur = next;
6259 }
6260 }
6261
6262 void G1CollectedHeap::set_free_regions_coming() {
6263 if (G1ConcRegionFreeingVerbose) {
6264 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6265 "setting free regions coming");
6266 }
6267
6268 assert(!free_regions_coming(), "pre-condition");
6269 _free_regions_coming = true;
6270 }
6271
6272 void G1CollectedHeap::reset_free_regions_coming() {
6273 assert(free_regions_coming(), "pre-condition");
6274
6275 {
6276 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6277 _free_regions_coming = false;
6278 SecondaryFreeList_lock->notify_all();
6279 }
6280
6281 if (G1ConcRegionFreeingVerbose) {
6282 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6283 "reset free regions coming");
6284 }
6285 }
6286
6287 void G1CollectedHeap::wait_while_free_regions_coming() {
6288 // Most of the time we won't have to wait, so let's do a quick test
6289 // first before we take the lock.
6290 if (!free_regions_coming()) {
6291 return;
6292 }
6293
6294 if (G1ConcRegionFreeingVerbose) {
6295 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6296 "waiting for free regions");
6297 }
6298
6299 {
6300 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6301 while (free_regions_coming()) {
6302 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6303 }
6304 }
6305
6306 if (G1ConcRegionFreeingVerbose) {
6307 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6308 "done waiting for free regions");
6309 }
6310 }
6311
6312 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6313 assert(heap_lock_held_for_gc(),
6314 "the heap lock should already be held by or for this thread");
6315 _young_list->push_region(hr);
6316 }
6317
6318 class NoYoungRegionsClosure: public HeapRegionClosure {
6319 private:
6320 bool _success;
6321 public:
6322 NoYoungRegionsClosure() : _success(true) { }
6323 bool doHeapRegion(HeapRegion* r) {
6324 if (r->is_young()) {
6325 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6326 r->bottom(), r->end());
6327 _success = false;
6328 }
6329 return false;
6330 }
6331 bool success() { return _success; }
6332 };
6333
6334 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6335 bool ret = _young_list->check_list_empty(check_sample);
6336
6337 if (check_heap) {
6338 NoYoungRegionsClosure closure;
6339 heap_region_iterate(&closure);
6340 ret = ret && closure.success();
6341 }
6342
6343 return ret;
6344 }
6345
6346 class TearDownRegionSetsClosure : public HeapRegionClosure {
6347 private:
6348 HeapRegionSet *_old_set;
6349
6350 public:
6351 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6352
6353 bool doHeapRegion(HeapRegion* r) {
6354 if (r->is_old()) {
6355 _old_set->remove(r);
6356 } else {
6357 // We ignore free regions, we'll empty the free list afterwards.
6358 // We ignore young regions, we'll empty the young list afterwards.
6359 // We ignore humongous regions, we're not tearing down the
6360 // humongous regions set.
6361 assert(r->is_free() || r->is_young() || r->is_humongous(),
6362 "it cannot be another type");
6363 }
6364 return false;
6365 }
6366
6367 ~TearDownRegionSetsClosure() {
6368 assert(_old_set->is_empty(), "post-condition");
6369 }
6370 };
6371
6372 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6373 assert_at_safepoint(true /* should_be_vm_thread */);
6374
6375 if (!free_list_only) {
6376 TearDownRegionSetsClosure cl(&_old_set);
6377 heap_region_iterate(&cl);
6378
6379 // Note that emptying the _young_list is postponed and instead done as
6380 // the first step when rebuilding the regions sets again. The reason for
6381 // this is that during a full GC string deduplication needs to know if
6382 // a collected region was young or old when the full GC was initiated.
6383 }
6384 _hrm.remove_all_free_regions();
6385 }
6386
6387 class RebuildRegionSetsClosure : public HeapRegionClosure {
6388 private:
6389 bool _free_list_only;
6390 HeapRegionSet* _old_set;
6391 HeapRegionManager* _hrm;
6392 size_t _total_used;
6393
6394 public:
6395 RebuildRegionSetsClosure(bool free_list_only,
6396 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6397 _free_list_only(free_list_only),
6398 _old_set(old_set), _hrm(hrm), _total_used(0) {
6399 assert(_hrm->num_free_regions() == 0, "pre-condition");
6400 if (!free_list_only) {
6401 assert(_old_set->is_empty(), "pre-condition");
6402 }
6403 }
6404
6405 bool doHeapRegion(HeapRegion* r) {
6406 if (r->is_continues_humongous()) {
6407 return false;
6408 }
6409
6410 if (r->is_empty()) {
6411 // Add free regions to the free list
6412 r->set_free();
6413 r->set_allocation_context(AllocationContext::system());
6414 _hrm->insert_into_free_list(r);
6415 } else if (!_free_list_only) {
6416 assert(!r->is_young(), "we should not come across young regions");
6417
6418 if (r->is_humongous()) {
6419 // We ignore humongous regions, we left the humongous set unchanged
6420 } else {
6421 // Objects that were compacted would have ended up on regions
6422 // that were previously old or free.
6423 assert(r->is_free() || r->is_old(), "invariant");
6424 // We now consider them old, so register as such.
6425 r->set_old();
6426 _old_set->add(r);
6427 }
6428 _total_used += r->used();
6429 }
6430
6431 return false;
6432 }
6433
6434 size_t total_used() {
6435 return _total_used;
6436 }
6437 };
6438
6439 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6440 assert_at_safepoint(true /* should_be_vm_thread */);
6441
6442 if (!free_list_only) {
6443 _young_list->empty_list();
6444 }
6445
6446 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6447 heap_region_iterate(&cl);
6448
6449 if (!free_list_only) {
6450 _allocator->set_used(cl.total_used());
6451 }
6452 assert(_allocator->used_unlocked() == recalculate_used(),
6453 err_msg("inconsistent _allocator->used_unlocked(), "
6454 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6455 _allocator->used_unlocked(), recalculate_used()));
6456 }
6457
6458 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6459 _refine_cte_cl->set_concurrent(concurrent);
6460 }
6461
6462 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6463 HeapRegion* hr = heap_region_containing(p);
6464 return hr->is_in(p);
6465 }
6466
6467 // Methods for the mutator alloc region
6468
6469 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6470 bool force) {
6471 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6472 assert(!force || g1_policy()->can_expand_young_list(),
6473 "if force is true we should be able to expand the young list");
6474 bool young_list_full = g1_policy()->is_young_list_full();
6475 if (force || !young_list_full) {
6476 HeapRegion* new_alloc_region = new_region(word_size,
6477 false /* is_old */,
6478 false /* do_expand */);
6479 if (new_alloc_region != NULL) {
6480 set_region_short_lived_locked(new_alloc_region);
6481 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6482 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6483 return new_alloc_region;
6484 }
6485 }
6486 return NULL;
6487 }
6488
6489 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6490 size_t allocated_bytes) {
6491 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6492 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6493
6494 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6495 _allocator->increase_used(allocated_bytes);
6496 _hr_printer.retire(alloc_region);
6497 // We update the eden sizes here, when the region is retired,
6498 // instead of when it's allocated, since this is the point that its
6499 // used space has been recored in _summary_bytes_used.
6500 g1mm()->update_eden_size();
6501 }
6502
6503 void G1CollectedHeap::set_par_threads() {
6504 // Don't change the number of workers. Use the value previously set
6505 // in the workgroup.
6506 uint n_workers = workers()->active_workers();
6507 assert(UseDynamicNumberOfGCThreads ||
6508 n_workers == workers()->total_workers(),
6509 "Otherwise should be using the total number of workers");
6510 if (n_workers == 0) {
6511 assert(false, "Should have been set in prior evacuation pause.");
6512 n_workers = ParallelGCThreads;
6513 workers()->set_active_workers(n_workers);
6514 }
6515 set_par_threads(n_workers);
6516 }
6517
6518 // Methods for the GC alloc regions
6519
6520 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6521 uint count,
6522 InCSetState dest) {
6523 assert(FreeList_lock->owned_by_self(), "pre-condition");
6524
6525 if (count < g1_policy()->max_regions(dest)) {
6526 const bool is_survivor = (dest.is_young());
6527 HeapRegion* new_alloc_region = new_region(word_size,
6528 !is_survivor,
6529 true /* do_expand */);
6530 if (new_alloc_region != NULL) {
6531 // We really only need to do this for old regions given that we
6532 // should never scan survivors. But it doesn't hurt to do it
6533 // for survivors too.
6534 new_alloc_region->record_timestamp();
6535 if (is_survivor) {
6536 new_alloc_region->set_survivor();
6537 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6538 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6539 } else {
6540 new_alloc_region->set_old();
6541 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6542 check_bitmaps("Old Region Allocation", new_alloc_region);
6543 }
6544 bool during_im = g1_policy()->during_initial_mark_pause();
6545 new_alloc_region->note_start_of_copying(during_im);
6546 return new_alloc_region;
6547 }
6548 }
6549 return NULL;
6550 }
6551
6552 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6553 size_t allocated_bytes,
6554 InCSetState dest) {
6555 bool during_im = g1_policy()->during_initial_mark_pause();
6556 alloc_region->note_end_of_copying(during_im);
6557 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6558 if (dest.is_young()) {
6559 young_list()->add_survivor_region(alloc_region);
6560 } else {
6561 _old_set.add(alloc_region);
6562 }
6563 _hr_printer.retire(alloc_region);
6564 }
6565
6566 // Heap region set verification
6567
6568 class VerifyRegionListsClosure : public HeapRegionClosure {
6569 private:
6570 HeapRegionSet* _old_set;
6571 HeapRegionSet* _humongous_set;
6572 HeapRegionManager* _hrm;
6573
6574 public:
6575 HeapRegionSetCount _old_count;
6576 HeapRegionSetCount _humongous_count;
6577 HeapRegionSetCount _free_count;
6578
6579 VerifyRegionListsClosure(HeapRegionSet* old_set,
6580 HeapRegionSet* humongous_set,
6581 HeapRegionManager* hrm) :
6582 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6583 _old_count(), _humongous_count(), _free_count(){ }
6584
6585 bool doHeapRegion(HeapRegion* hr) {
6586 if (hr->is_continues_humongous()) {
6587 return false;
6588 }
6589
6590 if (hr->is_young()) {
6591 // TODO
6592 } else if (hr->is_starts_humongous()) {
6593 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6594 _humongous_count.increment(1u, hr->capacity());
6595 } else if (hr->is_empty()) {
6596 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6597 _free_count.increment(1u, hr->capacity());
6598 } else if (hr->is_old()) {
6599 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6600 _old_count.increment(1u, hr->capacity());
6601 } else {
6602 ShouldNotReachHere();
6603 }
6604 return false;
6605 }
6606
6607 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6608 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6609 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6610 old_set->total_capacity_bytes(), _old_count.capacity()));
6611
6612 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6613 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6614 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6615
6616 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()));
6617 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6618 free_list->total_capacity_bytes(), _free_count.capacity()));
6619 }
6620 };
6621
6622 void G1CollectedHeap::verify_region_sets() {
6623 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6624
6625 // First, check the explicit lists.
6626 _hrm.verify();
6627 {
6628 // Given that a concurrent operation might be adding regions to
6629 // the secondary free list we have to take the lock before
6630 // verifying it.
6631 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6632 _secondary_free_list.verify_list();
6633 }
6634
6635 // If a concurrent region freeing operation is in progress it will
6636 // be difficult to correctly attributed any free regions we come
6637 // across to the correct free list given that they might belong to
6638 // one of several (free_list, secondary_free_list, any local lists,
6639 // etc.). So, if that's the case we will skip the rest of the
6640 // verification operation. Alternatively, waiting for the concurrent
6641 // operation to complete will have a non-trivial effect on the GC's
6642 // operation (no concurrent operation will last longer than the
6643 // interval between two calls to verification) and it might hide
6644 // any issues that we would like to catch during testing.
6645 if (free_regions_coming()) {
6646 return;
6647 }
6648
6649 // Make sure we append the secondary_free_list on the free_list so
6650 // that all free regions we will come across can be safely
6651 // attributed to the free_list.
6652 append_secondary_free_list_if_not_empty_with_lock();
6653
6654 // Finally, make sure that the region accounting in the lists is
6655 // consistent with what we see in the heap.
6656
6657 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6658 heap_region_iterate(&cl);
6659 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6660 }
6661
6662 // Optimized nmethod scanning
6663
6664 class RegisterNMethodOopClosure: public OopClosure {
6665 G1CollectedHeap* _g1h;
6666 nmethod* _nm;
6667
6668 template <class T> void do_oop_work(T* p) {
6669 T heap_oop = oopDesc::load_heap_oop(p);
6670 if (!oopDesc::is_null(heap_oop)) {
6671 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6672 HeapRegion* hr = _g1h->heap_region_containing(obj);
6673 assert(!hr->is_continues_humongous(),
6674 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6675 " starting at "HR_FORMAT,
6676 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6677
6678 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6679 hr->add_strong_code_root_locked(_nm);
6680 }
6681 }
6682
6683 public:
6684 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6685 _g1h(g1h), _nm(nm) {}
6686
6687 void do_oop(oop* p) { do_oop_work(p); }
6688 void do_oop(narrowOop* p) { do_oop_work(p); }
6689 };
6690
6691 class UnregisterNMethodOopClosure: public OopClosure {
6692 G1CollectedHeap* _g1h;
6693 nmethod* _nm;
6694
6695 template <class T> void do_oop_work(T* p) {
6696 T heap_oop = oopDesc::load_heap_oop(p);
6697 if (!oopDesc::is_null(heap_oop)) {
6698 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6699 HeapRegion* hr = _g1h->heap_region_containing(obj);
6700 assert(!hr->is_continues_humongous(),
6701 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6702 " starting at "HR_FORMAT,
6703 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6704
6705 hr->remove_strong_code_root(_nm);
6706 }
6707 }
6708
6709 public:
6710 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6711 _g1h(g1h), _nm(nm) {}
6712
6713 void do_oop(oop* p) { do_oop_work(p); }
6714 void do_oop(narrowOop* p) { do_oop_work(p); }
6715 };
6716
6717 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6718 CollectedHeap::register_nmethod(nm);
6719
6720 guarantee(nm != NULL, "sanity");
6721 RegisterNMethodOopClosure reg_cl(this, nm);
6722 nm->oops_do(®_cl);
6723 }
6724
6725 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6726 CollectedHeap::unregister_nmethod(nm);
6727
6728 guarantee(nm != NULL, "sanity");
6729 UnregisterNMethodOopClosure reg_cl(this, nm);
6730 nm->oops_do(®_cl, true);
6731 }
6732
6733 void G1CollectedHeap::purge_code_root_memory() {
6734 double purge_start = os::elapsedTime();
6735 G1CodeRootSet::purge();
6736 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6737 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6738 }
6739
6740 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6741 G1CollectedHeap* _g1h;
6742
6743 public:
6744 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6745 _g1h(g1h) {}
6746
6747 void do_code_blob(CodeBlob* cb) {
6748 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6749 if (nm == NULL) {
6750 return;
6751 }
6752
6753 if (ScavengeRootsInCode) {
6754 _g1h->register_nmethod(nm);
6755 }
6756 }
6757 };
6758
6759 void G1CollectedHeap::rebuild_strong_code_roots() {
6760 RebuildStrongCodeRootClosure blob_cl(this);
6761 CodeCache::blobs_do(&blob_cl);
6762 }