1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/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 g1_policy()->record_full_collection_start();
1233
1234 // Note: When we have a more flexible GC logging framework that
1235 // allows us to add optional attributes to a GC log record we
1236 // could consider timing and reporting how long we wait in the
1237 // following two methods.
1238 wait_while_free_regions_coming();
1239 // If we start the compaction before the CM threads finish
1240 // scanning the root regions we might trip them over as we'll
1241 // be moving objects / updating references. So let's wait until
1242 // they are done. By telling them to abort, they should complete
1243 // early.
1244 _cm->root_regions()->abort();
1245 _cm->root_regions()->wait_until_scan_finished();
1246 append_secondary_free_list_if_not_empty_with_lock();
1247
1248 gc_prologue(true);
1249 increment_total_collections(true /* full gc */);
1250 increment_old_marking_cycles_started();
1251
1252 assert(used() == recalculate_used(), "Should be equal");
1253
1254 verify_before_gc();
1255
1256 check_bitmaps("Full GC Start");
1257 pre_full_gc_dump(gc_timer);
1258
1259 COMPILER2_PRESENT(DerivedPointerTable::clear());
1260
1261 // Disable discovery and empty the discovered lists
1262 // for the CM ref processor.
1263 ref_processor_cm()->disable_discovery();
1264 ref_processor_cm()->abandon_partial_discovery();
1265 ref_processor_cm()->verify_no_references_recorded();
1266
1267 // Abandon current iterations of concurrent marking and concurrent
1268 // refinement, if any are in progress. We have to do this before
1269 // wait_until_scan_finished() below.
1270 concurrent_mark()->abort();
1271
1272 // Make sure we'll choose a new allocation region afterwards.
1273 _allocator->release_mutator_alloc_region();
1274 _allocator->abandon_gc_alloc_regions();
1275 g1_rem_set()->cleanupHRRS();
1276
1277 // We should call this after we retire any currently active alloc
1278 // regions so that all the ALLOC / RETIRE events are generated
1279 // before the start GC event.
1280 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1281
1282 // We may have added regions to the current incremental collection
1283 // set between the last GC or pause and now. We need to clear the
1284 // incremental collection set and then start rebuilding it afresh
1285 // after this full GC.
1286 abandon_collection_set(g1_policy()->inc_cset_head());
1287 g1_policy()->clear_incremental_cset();
1288 g1_policy()->stop_incremental_cset_building();
1289
1290 tear_down_region_sets(false /* free_list_only */);
1291 g1_policy()->set_gcs_are_young(true);
1292
1293 // See the comments in g1CollectedHeap.hpp and
1294 // G1CollectedHeap::ref_processing_init() about
1295 // how reference processing currently works in G1.
1296
1297 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1298 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1299
1300 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1301 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1302
1303 ref_processor_stw()->enable_discovery();
1304 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1305
1306 // Do collection work
1307 {
1308 HandleMark hm; // Discard invalid handles created during gc
1309 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1310 }
1311
1312 assert(num_free_regions() == 0, "we should not have added any free regions");
1313 rebuild_region_sets(false /* free_list_only */);
1314
1315 // Enqueue any discovered reference objects that have
1316 // not been removed from the discovered lists.
1317 ref_processor_stw()->enqueue_discovered_references();
1318
1319 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1320
1321 MemoryService::track_memory_usage();
1322
1323 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1324 ref_processor_stw()->verify_no_references_recorded();
1325
1326 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1327 ClassLoaderDataGraph::purge();
1328 MetaspaceAux::verify_metrics();
1329
1330 // Note: since we've just done a full GC, concurrent
1331 // marking is no longer active. Therefore we need not
1332 // re-enable reference discovery for the CM ref processor.
1333 // That will be done at the start of the next marking cycle.
1334 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1335 ref_processor_cm()->verify_no_references_recorded();
1336
1337 reset_gc_time_stamp();
1338 // Since everything potentially moved, we will clear all remembered
1339 // sets, and clear all cards. Later we will rebuild remembered
1340 // sets. We will also reset the GC time stamps of the regions.
1341 clear_rsets_post_compaction();
1342 check_gc_time_stamps();
1343
1344 // Resize the heap if necessary.
1345 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1346
1347 if (_hr_printer.is_active()) {
1348 // We should do this after we potentially resize the heap so
1349 // that all the COMMIT / UNCOMMIT events are generated before
1350 // the end GC event.
1351
1352 print_hrm_post_compaction();
1353 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1354 }
1355
1356 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1357 if (hot_card_cache->use_cache()) {
1358 hot_card_cache->reset_card_counts();
1359 hot_card_cache->reset_hot_cache();
1360 }
1361
1362 // Rebuild remembered sets of all regions.
1363 uint n_workers =
1364 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1365 workers()->active_workers(),
1366 Threads::number_of_non_daemon_threads());
1367 assert(UseDynamicNumberOfGCThreads ||
1368 n_workers == workers()->total_workers(),
1369 "If not dynamic should be using all the workers");
1370 workers()->set_active_workers(n_workers);
1371 // Set parallel threads in the heap (_n_par_threads) only
1372 // before a parallel phase and always reset it to 0 after
1373 // the phase so that the number of parallel threads does
1374 // no get carried forward to a serial phase where there
1375 // may be code that is "possibly_parallel".
1376 set_par_threads(n_workers);
1377
1378 ParRebuildRSTask rebuild_rs_task(this);
1379 assert(UseDynamicNumberOfGCThreads ||
1380 workers()->active_workers() == workers()->total_workers(),
1381 "Unless dynamic should use total workers");
1382 // Use the most recent number of active workers
1383 assert(workers()->active_workers() > 0,
1384 "Active workers not properly set");
1385 set_par_threads(workers()->active_workers());
1386 workers()->run_task(&rebuild_rs_task);
1387 set_par_threads(0);
1388
1389 // Rebuild the strong code root lists for each region
1390 rebuild_strong_code_roots();
1391
1392 if (true) { // FIXME
1393 MetaspaceGC::compute_new_size();
1394 }
1395
1396 #ifdef TRACESPINNING
1397 ParallelTaskTerminator::print_termination_counts();
1398 #endif
1399
1400 // Discard all rset updates
1401 JavaThread::dirty_card_queue_set().abandon_logs();
1402 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1403
1404 _young_list->reset_sampled_info();
1405 // At this point there should be no regions in the
1406 // entire heap tagged as young.
1407 assert(check_young_list_empty(true /* check_heap */),
1408 "young list should be empty at this point");
1409
1410 // Update the number of full collections that have been completed.
1411 increment_old_marking_cycles_completed(false /* concurrent */);
1412
1413 _hrm.verify_optional();
1414 verify_region_sets_optional();
1415
1416 verify_after_gc();
1417
1418 // Clear the previous marking bitmap, if needed for bitmap verification.
1419 // Note we cannot do this when we clear the next marking bitmap in
1420 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1421 // objects marked during a full GC against the previous bitmap.
1422 // But we need to clear it before calling check_bitmaps below since
1423 // the full GC has compacted objects and updated TAMS but not updated
1424 // the prev bitmap.
1425 if (G1VerifyBitmaps) {
1426 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1427 }
1428 check_bitmaps("Full GC End");
1429
1430 // Start a new incremental collection set for the next pause
1431 assert(g1_policy()->collection_set() == NULL, "must be");
1432 g1_policy()->start_incremental_cset_building();
1433
1434 clear_cset_fast_test();
1435
1436 _allocator->init_mutator_alloc_region();
1437
1438 g1_policy()->record_full_collection_end();
1439
1440 if (G1Log::fine()) {
1441 g1_policy()->print_heap_transition();
1442 }
1443
1444 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1445 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1446 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1447 // before any GC notifications are raised.
1448 g1mm()->update_sizes();
1449
1450 gc_epilogue(true);
1451 }
1452
1453 if (G1Log::finer()) {
1454 g1_policy()->print_detailed_heap_transition(true /* full */);
1455 }
1456
1457 print_heap_after_gc();
1458 trace_heap_after_gc(gc_tracer);
1459
1460 post_full_gc_dump(gc_timer);
1461
1462 gc_timer->register_gc_end();
1463 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1464 }
1465
1466 return true;
1467 }
1468
1469 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1470 // do_collection() will return whether it succeeded in performing
1471 // the GC. Currently, there is no facility on the
1472 // do_full_collection() API to notify the caller than the collection
1473 // did not succeed (e.g., because it was locked out by the GC
1474 // locker). So, right now, we'll ignore the return value.
1475 bool dummy = do_collection(true, /* explicit_gc */
1476 clear_all_soft_refs,
1477 0 /* word_size */);
1478 }
1479
1480 // This code is mostly copied from TenuredGeneration.
1481 void
1482 G1CollectedHeap::
1483 resize_if_necessary_after_full_collection(size_t word_size) {
1484 // Include the current allocation, if any, and bytes that will be
1485 // pre-allocated to support collections, as "used".
1486 const size_t used_after_gc = used();
1487 const size_t capacity_after_gc = capacity();
1488 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1489
1490 // This is enforced in arguments.cpp.
1491 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1492 "otherwise the code below doesn't make sense");
1493
1494 // We don't have floating point command-line arguments
1495 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1496 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1497 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1498 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1499
1500 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1501 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1502
1503 // We have to be careful here as these two calculations can overflow
1504 // 32-bit size_t's.
1505 double used_after_gc_d = (double) used_after_gc;
1506 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1507 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1508
1509 // Let's make sure that they are both under the max heap size, which
1510 // by default will make them fit into a size_t.
1511 double desired_capacity_upper_bound = (double) max_heap_size;
1512 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1513 desired_capacity_upper_bound);
1514 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1515 desired_capacity_upper_bound);
1516
1517 // We can now safely turn them into size_t's.
1518 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1519 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1520
1521 // This assert only makes sense here, before we adjust them
1522 // with respect to the min and max heap size.
1523 assert(minimum_desired_capacity <= maximum_desired_capacity,
1524 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1525 "maximum_desired_capacity = "SIZE_FORMAT,
1526 minimum_desired_capacity, maximum_desired_capacity));
1527
1528 // Should not be greater than the heap max size. No need to adjust
1529 // it with respect to the heap min size as it's a lower bound (i.e.,
1530 // we'll try to make the capacity larger than it, not smaller).
1531 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1532 // Should not be less than the heap min size. No need to adjust it
1533 // with respect to the heap max size as it's an upper bound (i.e.,
1534 // we'll try to make the capacity smaller than it, not greater).
1535 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1536
1537 if (capacity_after_gc < minimum_desired_capacity) {
1538 // Don't expand unless it's significant
1539 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1540 ergo_verbose4(ErgoHeapSizing,
1541 "attempt heap expansion",
1542 ergo_format_reason("capacity lower than "
1543 "min desired capacity after Full GC")
1544 ergo_format_byte("capacity")
1545 ergo_format_byte("occupancy")
1546 ergo_format_byte_perc("min desired capacity"),
1547 capacity_after_gc, used_after_gc,
1548 minimum_desired_capacity, (double) MinHeapFreeRatio);
1549 expand(expand_bytes);
1550
1551 // No expansion, now see if we want to shrink
1552 } else if (capacity_after_gc > maximum_desired_capacity) {
1553 // Capacity too large, compute shrinking size
1554 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1555 ergo_verbose4(ErgoHeapSizing,
1556 "attempt heap shrinking",
1557 ergo_format_reason("capacity higher than "
1558 "max desired capacity after Full GC")
1559 ergo_format_byte("capacity")
1560 ergo_format_byte("occupancy")
1561 ergo_format_byte_perc("max desired capacity"),
1562 capacity_after_gc, used_after_gc,
1563 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1564 shrink(shrink_bytes);
1565 }
1566 }
1567
1568
1569 HeapWord*
1570 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1571 AllocationContext_t context,
1572 bool* succeeded) {
1573 assert_at_safepoint(true /* should_be_vm_thread */);
1574
1575 *succeeded = true;
1576 // Let's attempt the allocation first.
1577 HeapWord* result =
1578 attempt_allocation_at_safepoint(word_size,
1579 context,
1580 false /* expect_null_mutator_alloc_region */);
1581 if (result != NULL) {
1582 assert(*succeeded, "sanity");
1583 return result;
1584 }
1585
1586 // In a G1 heap, we're supposed to keep allocation from failing by
1587 // incremental pauses. Therefore, at least for now, we'll favor
1588 // expansion over collection. (This might change in the future if we can
1589 // do something smarter than full collection to satisfy a failed alloc.)
1590 result = expand_and_allocate(word_size, context);
1591 if (result != NULL) {
1592 assert(*succeeded, "sanity");
1593 return result;
1594 }
1595
1596 // Expansion didn't work, we'll try to do a Full GC.
1597 bool gc_succeeded = do_collection(false, /* explicit_gc */
1598 false, /* clear_all_soft_refs */
1599 word_size);
1600 if (!gc_succeeded) {
1601 *succeeded = false;
1602 return NULL;
1603 }
1604
1605 // Retry the allocation
1606 result = attempt_allocation_at_safepoint(word_size,
1607 context,
1608 true /* expect_null_mutator_alloc_region */);
1609 if (result != NULL) {
1610 assert(*succeeded, "sanity");
1611 return result;
1612 }
1613
1614 // Then, try a Full GC that will collect all soft references.
1615 gc_succeeded = do_collection(false, /* explicit_gc */
1616 true, /* clear_all_soft_refs */
1617 word_size);
1618 if (!gc_succeeded) {
1619 *succeeded = false;
1620 return NULL;
1621 }
1622
1623 // Retry the allocation once more
1624 result = attempt_allocation_at_safepoint(word_size,
1625 context,
1626 true /* expect_null_mutator_alloc_region */);
1627 if (result != NULL) {
1628 assert(*succeeded, "sanity");
1629 return result;
1630 }
1631
1632 assert(!collector_policy()->should_clear_all_soft_refs(),
1633 "Flag should have been handled and cleared prior to this point");
1634
1635 // What else? We might try synchronous finalization later. If the total
1636 // space available is large enough for the allocation, then a more
1637 // complete compaction phase than we've tried so far might be
1638 // appropriate.
1639 assert(*succeeded, "sanity");
1640 return NULL;
1641 }
1642
1643 // Attempting to expand the heap sufficiently
1644 // to support an allocation of the given "word_size". If
1645 // successful, perform the allocation and return the address of the
1646 // allocated block, or else "NULL".
1647
1648 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1649 assert_at_safepoint(true /* should_be_vm_thread */);
1650
1651 verify_region_sets_optional();
1652
1653 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1654 ergo_verbose1(ErgoHeapSizing,
1655 "attempt heap expansion",
1656 ergo_format_reason("allocation request failed")
1657 ergo_format_byte("allocation request"),
1658 word_size * HeapWordSize);
1659 if (expand(expand_bytes)) {
1660 _hrm.verify_optional();
1661 verify_region_sets_optional();
1662 return attempt_allocation_at_safepoint(word_size,
1663 context,
1664 false /* expect_null_mutator_alloc_region */);
1665 }
1666 return NULL;
1667 }
1668
1669 bool G1CollectedHeap::expand(size_t expand_bytes) {
1670 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1671 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1672 HeapRegion::GrainBytes);
1673 ergo_verbose2(ErgoHeapSizing,
1674 "expand the heap",
1675 ergo_format_byte("requested expansion amount")
1676 ergo_format_byte("attempted expansion amount"),
1677 expand_bytes, aligned_expand_bytes);
1678
1679 if (is_maximal_no_gc()) {
1680 ergo_verbose0(ErgoHeapSizing,
1681 "did not expand the heap",
1682 ergo_format_reason("heap already fully expanded"));
1683 return false;
1684 }
1685
1686 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1687 assert(regions_to_expand > 0, "Must expand by at least one region");
1688
1689 uint expanded_by = _hrm.expand_by(regions_to_expand);
1690
1691 if (expanded_by > 0) {
1692 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1693 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1694 g1_policy()->record_new_heap_size(num_regions());
1695 } else {
1696 ergo_verbose0(ErgoHeapSizing,
1697 "did not expand the heap",
1698 ergo_format_reason("heap expansion operation failed"));
1699 // The expansion of the virtual storage space was unsuccessful.
1700 // Let's see if it was because we ran out of swap.
1701 if (G1ExitOnExpansionFailure &&
1702 _hrm.available() >= regions_to_expand) {
1703 // We had head room...
1704 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1705 }
1706 }
1707 return regions_to_expand > 0;
1708 }
1709
1710 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1711 size_t aligned_shrink_bytes =
1712 ReservedSpace::page_align_size_down(shrink_bytes);
1713 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1714 HeapRegion::GrainBytes);
1715 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1716
1717 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1718 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1719
1720 ergo_verbose3(ErgoHeapSizing,
1721 "shrink the heap",
1722 ergo_format_byte("requested shrinking amount")
1723 ergo_format_byte("aligned shrinking amount")
1724 ergo_format_byte("attempted shrinking amount"),
1725 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1726 if (num_regions_removed > 0) {
1727 g1_policy()->record_new_heap_size(num_regions());
1728 } else {
1729 ergo_verbose0(ErgoHeapSizing,
1730 "did not shrink the heap",
1731 ergo_format_reason("heap shrinking operation failed"));
1732 }
1733 }
1734
1735 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1736 verify_region_sets_optional();
1737
1738 // We should only reach here at the end of a Full GC which means we
1739 // should not not be holding to any GC alloc regions. The method
1740 // below will make sure of that and do any remaining clean up.
1741 _allocator->abandon_gc_alloc_regions();
1742
1743 // Instead of tearing down / rebuilding the free lists here, we
1744 // could instead use the remove_all_pending() method on free_list to
1745 // remove only the ones that we need to remove.
1746 tear_down_region_sets(true /* free_list_only */);
1747 shrink_helper(shrink_bytes);
1748 rebuild_region_sets(true /* free_list_only */);
1749
1750 _hrm.verify_optional();
1751 verify_region_sets_optional();
1752 }
1753
1754 // Public methods.
1755
1756 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1757 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1758 #endif // _MSC_VER
1759
1760
1761 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1762 SharedHeap(policy_),
1763 _g1_policy(policy_),
1764 _dirty_card_queue_set(false),
1765 _into_cset_dirty_card_queue_set(false),
1766 _is_alive_closure_cm(this),
1767 _is_alive_closure_stw(this),
1768 _ref_processor_cm(NULL),
1769 _ref_processor_stw(NULL),
1770 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1771 _bot_shared(NULL),
1772 _evac_failure_scan_stack(NULL),
1773 _mark_in_progress(false),
1774 _cg1r(NULL),
1775 _g1mm(NULL),
1776 _refine_cte_cl(NULL),
1777 _full_collection(false),
1778 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1779 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1780 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1781 _humongous_is_live(),
1782 _has_humongous_reclaim_candidates(false),
1783 _free_regions_coming(false),
1784 _young_list(new YoungList(this)),
1785 _gc_time_stamp(0),
1786 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1787 _old_plab_stats(OldPLABSize, PLABWeight),
1788 _expand_heap_after_alloc_failure(true),
1789 _surviving_young_words(NULL),
1790 _old_marking_cycles_started(0),
1791 _old_marking_cycles_completed(0),
1792 _concurrent_cycle_started(false),
1793 _heap_summary_sent(false),
1794 _in_cset_fast_test(),
1795 _dirty_cards_region_list(NULL),
1796 _worker_cset_start_region(NULL),
1797 _worker_cset_start_region_time_stamp(NULL),
1798 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1799 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1800 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1801 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1802
1803 _g1h = this;
1804 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1805 vm_exit_during_initialization("Failed necessary allocation.");
1806 }
1807
1808 _allocator = G1Allocator::create_allocator(_g1h);
1809 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1810
1811 int n_queues = MAX2((int)ParallelGCThreads, 1);
1812 _task_queues = new RefToScanQueueSet(n_queues);
1813
1814 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1815 assert(n_rem_sets > 0, "Invariant.");
1816
1817 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1818 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1819 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1820
1821 for (int i = 0; i < n_queues; i++) {
1822 RefToScanQueue* q = new RefToScanQueue();
1823 q->initialize();
1824 _task_queues->register_queue(i, q);
1825 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1826 }
1827 clear_cset_start_regions();
1828
1829 // Initialize the G1EvacuationFailureALot counters and flags.
1830 NOT_PRODUCT(reset_evacuation_should_fail();)
1831
1832 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1833 }
1834
1835 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1836 size_t size,
1837 size_t translation_factor) {
1838 // Determine the preferred page size for the auxiliary data structures. We always
1839 // prefer large pages if the given size allows it for performance reasons.
1840 size_t const commit_size = os::page_size_for_region_unaligned(size, 1);
1841 // The base address reserved space must be aligned to that page. Otherwise we
1842 // would need to split pages (or it would be completely impossible) when
1843 // uncommitting memory within the heap.
1844 // Size need *not* be aligned to above calculated commit size.
1845 size_t const alignment = MAX2(commit_size, (size_t)os::vm_allocation_granularity());
1846 bool const use_large_pages = commit_size != (size_t)os::vm_page_size() ? UseLargePages : false;
1847 ReservedSpace rs(align_size_up(size, alignment), alignment, use_large_pages);
1848 G1RegionToSpaceMapper* result =
1849 G1RegionToSpaceMapper::create_mapper(rs,
1850 size,
1851 commit_size,
1852 HeapRegion::GrainBytes,
1853 translation_factor,
1854 mtGC);
1855 if (TracePageSizes) {
1856 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT" base=" PTR_FORMAT" size=" SIZE_FORMAT" alignment=" SIZE_FORMAT" reqsize=" SIZE_FORMAT,
1857 description, commit_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1858 }
1859 return result;
1860 }
1861
1862 jint G1CollectedHeap::initialize() {
1863 CollectedHeap::pre_initialize();
1864 os::enable_vtime();
1865
1866 G1Log::init();
1867
1868 // Necessary to satisfy locking discipline assertions.
1869
1870 MutexLocker x(Heap_lock);
1871
1872 // We have to initialize the printer before committing the heap, as
1873 // it will be used then.
1874 _hr_printer.set_active(G1PrintHeapRegions);
1875
1876 // While there are no constraints in the GC code that HeapWordSize
1877 // be any particular value, there are multiple other areas in the
1878 // system which believe this to be true (e.g. oop->object_size in some
1879 // cases incorrectly returns the size in wordSize units rather than
1880 // HeapWordSize).
1881 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1882
1883 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1884 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1885 size_t heap_alignment = collector_policy()->heap_alignment();
1886
1887 // Ensure that the sizes are properly aligned.
1888 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1889 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1890 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1891
1892 _refine_cte_cl = new RefineCardTableEntryClosure();
1893
1894 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1895
1896 // Reserve the maximum.
1897
1898 // When compressed oops are enabled, the preferred heap base
1899 // is calculated by subtracting the requested size from the
1900 // 32Gb boundary and using the result as the base address for
1901 // heap reservation. If the requested size is not aligned to
1902 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1903 // into the ReservedHeapSpace constructor) then the actual
1904 // base of the reserved heap may end up differing from the
1905 // address that was requested (i.e. the preferred heap base).
1906 // If this happens then we could end up using a non-optimal
1907 // compressed oops mode.
1908
1909 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1910 heap_alignment);
1911
1912 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1913
1914 // Create the barrier set for the entire reserved region.
1915 G1SATBCardTableLoggingModRefBS* bs
1916 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1917 bs->initialize();
1918 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1919 set_barrier_set(bs);
1920
1921 // Also create a G1 rem set.
1922 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1923
1924 // Carve out the G1 part of the heap.
1925
1926 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1927 G1RegionToSpaceMapper* heap_storage =
1928 G1RegionToSpaceMapper::create_mapper(g1_rs,
1929 g1_rs.size(),
1930 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1931 HeapRegion::GrainBytes,
1932 1,
1933 mtJavaHeap);
1934 heap_storage->set_mapping_changed_listener(&_listener);
1935
1936 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1937 G1RegionToSpaceMapper* bot_storage =
1938 create_aux_memory_mapper("Block offset table",
1939 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1940 G1BlockOffsetSharedArray::N_bytes);
1941
1942 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1943 G1RegionToSpaceMapper* cardtable_storage =
1944 create_aux_memory_mapper("Card table",
1945 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1946 G1BlockOffsetSharedArray::N_bytes);
1947
1948 G1RegionToSpaceMapper* card_counts_storage =
1949 create_aux_memory_mapper("Card counts table",
1950 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1951 G1BlockOffsetSharedArray::N_bytes);
1952
1953 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1954 G1RegionToSpaceMapper* prev_bitmap_storage =
1955 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1956 G1RegionToSpaceMapper* next_bitmap_storage =
1957 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1958
1959 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1960 g1_barrier_set()->initialize(cardtable_storage);
1961 // Do later initialization work for concurrent refinement.
1962 _cg1r->init(card_counts_storage);
1963
1964 // 6843694 - ensure that the maximum region index can fit
1965 // in the remembered set structures.
1966 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1967 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1968
1969 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1970 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1971 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1972 "too many cards per region");
1973
1974 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1975
1976 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1977
1978 _g1h = this;
1979
1980 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1981 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1982
1983 // Create the ConcurrentMark data structure and thread.
1984 // (Must do this late, so that "max_regions" is defined.)
1985 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1986 if (_cm == NULL || !_cm->completed_initialization()) {
1987 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1988 return JNI_ENOMEM;
1989 }
1990 _cmThread = _cm->cmThread();
1991
1992 // Initialize the from_card cache structure of HeapRegionRemSet.
1993 HeapRegionRemSet::init_heap(max_regions());
1994
1995 // Now expand into the initial heap size.
1996 if (!expand(init_byte_size)) {
1997 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1998 return JNI_ENOMEM;
1999 }
2000
2001 // Perform any initialization actions delegated to the policy.
2002 g1_policy()->init();
2003
2004 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2005 SATB_Q_FL_lock,
2006 G1SATBProcessCompletedThreshold,
2007 Shared_SATB_Q_lock);
2008
2009 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2010 DirtyCardQ_CBL_mon,
2011 DirtyCardQ_FL_lock,
2012 concurrent_g1_refine()->yellow_zone(),
2013 concurrent_g1_refine()->red_zone(),
2014 Shared_DirtyCardQ_lock);
2015
2016 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2017 DirtyCardQ_CBL_mon,
2018 DirtyCardQ_FL_lock,
2019 -1, // never trigger processing
2020 -1, // no limit on length
2021 Shared_DirtyCardQ_lock,
2022 &JavaThread::dirty_card_queue_set());
2023
2024 // Initialize the card queue set used to hold cards containing
2025 // references into the collection set.
2026 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2027 DirtyCardQ_CBL_mon,
2028 DirtyCardQ_FL_lock,
2029 -1, // never trigger processing
2030 -1, // no limit on length
2031 Shared_DirtyCardQ_lock,
2032 &JavaThread::dirty_card_queue_set());
2033
2034 // In case we're keeping closure specialization stats, initialize those
2035 // counts and that mechanism.
2036 SpecializationStats::clear();
2037
2038 // Here we allocate the dummy HeapRegion that is required by the
2039 // G1AllocRegion class.
2040 HeapRegion* dummy_region = _hrm.get_dummy_region();
2041
2042 // We'll re-use the same region whether the alloc region will
2043 // require BOT updates or not and, if it doesn't, then a non-young
2044 // region will complain that it cannot support allocations without
2045 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2046 dummy_region->set_eden();
2047 // Make sure it's full.
2048 dummy_region->set_top(dummy_region->end());
2049 G1AllocRegion::setup(this, dummy_region);
2050
2051 _allocator->init_mutator_alloc_region();
2052
2053 // Do create of the monitoring and management support so that
2054 // values in the heap have been properly initialized.
2055 _g1mm = new G1MonitoringSupport(this);
2056
2057 G1StringDedup::initialize();
2058
2059 return JNI_OK;
2060 }
2061
2062 void G1CollectedHeap::stop() {
2063 // Stop all concurrent threads. We do this to make sure these threads
2064 // do not continue to execute and access resources (e.g. gclog_or_tty)
2065 // that are destroyed during shutdown.
2066 _cg1r->stop();
2067 _cmThread->stop();
2068 if (G1StringDedup::is_enabled()) {
2069 G1StringDedup::stop();
2070 }
2071 }
2072
2073 void G1CollectedHeap::clear_humongous_is_live_table() {
2074 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2075 _humongous_is_live.clear();
2076 }
2077
2078 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2079 return HeapRegion::max_region_size();
2080 }
2081
2082 void G1CollectedHeap::ref_processing_init() {
2083 // Reference processing in G1 currently works as follows:
2084 //
2085 // * There are two reference processor instances. One is
2086 // used to record and process discovered references
2087 // during concurrent marking; the other is used to
2088 // record and process references during STW pauses
2089 // (both full and incremental).
2090 // * Both ref processors need to 'span' the entire heap as
2091 // the regions in the collection set may be dotted around.
2092 //
2093 // * For the concurrent marking ref processor:
2094 // * Reference discovery is enabled at initial marking.
2095 // * Reference discovery is disabled and the discovered
2096 // references processed etc during remarking.
2097 // * Reference discovery is MT (see below).
2098 // * Reference discovery requires a barrier (see below).
2099 // * Reference processing may or may not be MT
2100 // (depending on the value of ParallelRefProcEnabled
2101 // and ParallelGCThreads).
2102 // * A full GC disables reference discovery by the CM
2103 // ref processor and abandons any entries on it's
2104 // discovered lists.
2105 //
2106 // * For the STW processor:
2107 // * Non MT discovery is enabled at the start of a full GC.
2108 // * Processing and enqueueing during a full GC is non-MT.
2109 // * During a full GC, references are processed after marking.
2110 //
2111 // * Discovery (may or may not be MT) is enabled at the start
2112 // of an incremental evacuation pause.
2113 // * References are processed near the end of a STW evacuation pause.
2114 // * For both types of GC:
2115 // * Discovery is atomic - i.e. not concurrent.
2116 // * Reference discovery will not need a barrier.
2117
2118 SharedHeap::ref_processing_init();
2119 MemRegion mr = reserved_region();
2120
2121 // Concurrent Mark ref processor
2122 _ref_processor_cm =
2123 new ReferenceProcessor(mr, // span
2124 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2125 // mt processing
2126 (int) ParallelGCThreads,
2127 // degree of mt processing
2128 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2129 // mt discovery
2130 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2131 // degree of mt discovery
2132 false,
2133 // Reference discovery is not atomic
2134 &_is_alive_closure_cm);
2135 // is alive closure
2136 // (for efficiency/performance)
2137
2138 // STW ref processor
2139 _ref_processor_stw =
2140 new ReferenceProcessor(mr, // span
2141 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2142 // mt processing
2143 MAX2((int)ParallelGCThreads, 1),
2144 // degree of mt processing
2145 (ParallelGCThreads > 1),
2146 // mt discovery
2147 MAX2((int)ParallelGCThreads, 1),
2148 // degree of mt discovery
2149 true,
2150 // Reference discovery is atomic
2151 &_is_alive_closure_stw);
2152 // is alive closure
2153 // (for efficiency/performance)
2154 }
2155
2156 size_t G1CollectedHeap::capacity() const {
2157 return _hrm.length() * HeapRegion::GrainBytes;
2158 }
2159
2160 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2161 assert(!hr->is_continues_humongous(), "pre-condition");
2162 hr->reset_gc_time_stamp();
2163 if (hr->is_starts_humongous()) {
2164 uint first_index = hr->hrm_index() + 1;
2165 uint last_index = hr->last_hc_index();
2166 for (uint i = first_index; i < last_index; i += 1) {
2167 HeapRegion* chr = region_at(i);
2168 assert(chr->is_continues_humongous(), "sanity");
2169 chr->reset_gc_time_stamp();
2170 }
2171 }
2172 }
2173
2174 #ifndef PRODUCT
2175 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2176 private:
2177 unsigned _gc_time_stamp;
2178 bool _failures;
2179
2180 public:
2181 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2182 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2183
2184 virtual bool doHeapRegion(HeapRegion* hr) {
2185 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2186 if (_gc_time_stamp != region_gc_time_stamp) {
2187 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2188 "expected %d", HR_FORMAT_PARAMS(hr),
2189 region_gc_time_stamp, _gc_time_stamp);
2190 _failures = true;
2191 }
2192 return false;
2193 }
2194
2195 bool failures() { return _failures; }
2196 };
2197
2198 void G1CollectedHeap::check_gc_time_stamps() {
2199 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2200 heap_region_iterate(&cl);
2201 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2202 }
2203 #endif // PRODUCT
2204
2205 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2206 DirtyCardQueue* into_cset_dcq,
2207 bool concurrent,
2208 uint worker_i) {
2209 // Clean cards in the hot card cache
2210 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2211 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2212
2213 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2214 int n_completed_buffers = 0;
2215 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2216 n_completed_buffers++;
2217 }
2218 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2219 dcqs.clear_n_completed_buffers();
2220 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2221 }
2222
2223
2224 // Computes the sum of the storage used by the various regions.
2225 size_t G1CollectedHeap::used() const {
2226 return _allocator->used();
2227 }
2228
2229 size_t G1CollectedHeap::used_unlocked() const {
2230 return _allocator->used_unlocked();
2231 }
2232
2233 class SumUsedClosure: public HeapRegionClosure {
2234 size_t _used;
2235 public:
2236 SumUsedClosure() : _used(0) {}
2237 bool doHeapRegion(HeapRegion* r) {
2238 if (!r->is_continues_humongous()) {
2239 _used += r->used();
2240 }
2241 return false;
2242 }
2243 size_t result() { return _used; }
2244 };
2245
2246 size_t G1CollectedHeap::recalculate_used() const {
2247 double recalculate_used_start = os::elapsedTime();
2248
2249 SumUsedClosure blk;
2250 heap_region_iterate(&blk);
2251
2252 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2253 return blk.result();
2254 }
2255
2256 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2257 switch (cause) {
2258 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2259 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2260 case GCCause::_g1_humongous_allocation: return true;
2261 case GCCause::_update_allocation_context_stats_inc: return true;
2262 case GCCause::_wb_conc_mark: return true;
2263 default: return false;
2264 }
2265 }
2266
2267 #ifndef PRODUCT
2268 void G1CollectedHeap::allocate_dummy_regions() {
2269 // Let's fill up most of the region
2270 size_t word_size = HeapRegion::GrainWords - 1024;
2271 // And as a result the region we'll allocate will be humongous.
2272 guarantee(is_humongous(word_size), "sanity");
2273
2274 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2275 // Let's use the existing mechanism for the allocation
2276 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2277 AllocationContext::system());
2278 if (dummy_obj != NULL) {
2279 MemRegion mr(dummy_obj, word_size);
2280 CollectedHeap::fill_with_object(mr);
2281 } else {
2282 // If we can't allocate once, we probably cannot allocate
2283 // again. Let's get out of the loop.
2284 break;
2285 }
2286 }
2287 }
2288 #endif // !PRODUCT
2289
2290 void G1CollectedHeap::increment_old_marking_cycles_started() {
2291 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2292 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2293 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2294 _old_marking_cycles_started, _old_marking_cycles_completed));
2295
2296 _old_marking_cycles_started++;
2297 }
2298
2299 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2300 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2301
2302 // We assume that if concurrent == true, then the caller is a
2303 // concurrent thread that was joined the Suspendible Thread
2304 // Set. If there's ever a cheap way to check this, we should add an
2305 // assert here.
2306
2307 // Given that this method is called at the end of a Full GC or of a
2308 // concurrent cycle, and those can be nested (i.e., a Full GC can
2309 // interrupt a concurrent cycle), the number of full collections
2310 // completed should be either one (in the case where there was no
2311 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2312 // behind the number of full collections started.
2313
2314 // This is the case for the inner caller, i.e. a Full GC.
2315 assert(concurrent ||
2316 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2317 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2318 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2319 "is inconsistent with _old_marking_cycles_completed = %u",
2320 _old_marking_cycles_started, _old_marking_cycles_completed));
2321
2322 // This is the case for the outer caller, i.e. the concurrent cycle.
2323 assert(!concurrent ||
2324 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2325 err_msg("for outer caller (concurrent cycle): "
2326 "_old_marking_cycles_started = %u "
2327 "is inconsistent with _old_marking_cycles_completed = %u",
2328 _old_marking_cycles_started, _old_marking_cycles_completed));
2329
2330 _old_marking_cycles_completed += 1;
2331
2332 // We need to clear the "in_progress" flag in the CM thread before
2333 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2334 // is set) so that if a waiter requests another System.gc() it doesn't
2335 // incorrectly see that a marking cycle is still in progress.
2336 if (concurrent) {
2337 _cmThread->clear_in_progress();
2338 }
2339
2340 // This notify_all() will ensure that a thread that called
2341 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2342 // and it's waiting for a full GC to finish will be woken up. It is
2343 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2344 FullGCCount_lock->notify_all();
2345 }
2346
2347 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2348 _concurrent_cycle_started = true;
2349 _gc_timer_cm->register_gc_start(start_time);
2350
2351 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2352 trace_heap_before_gc(_gc_tracer_cm);
2353 }
2354
2355 void G1CollectedHeap::register_concurrent_cycle_end() {
2356 if (_concurrent_cycle_started) {
2357 if (_cm->has_aborted()) {
2358 _gc_tracer_cm->report_concurrent_mode_failure();
2359 }
2360
2361 _gc_timer_cm->register_gc_end();
2362 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2363
2364 // Clear state variables to prepare for the next concurrent cycle.
2365 _concurrent_cycle_started = false;
2366 _heap_summary_sent = false;
2367 }
2368 }
2369
2370 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2371 if (_concurrent_cycle_started) {
2372 // This function can be called when:
2373 // the cleanup pause is run
2374 // the concurrent cycle is aborted before the cleanup pause.
2375 // the concurrent cycle is aborted after the cleanup pause,
2376 // but before the concurrent cycle end has been registered.
2377 // Make sure that we only send the heap information once.
2378 if (!_heap_summary_sent) {
2379 trace_heap_after_gc(_gc_tracer_cm);
2380 _heap_summary_sent = true;
2381 }
2382 }
2383 }
2384
2385 G1YCType G1CollectedHeap::yc_type() {
2386 bool is_young = g1_policy()->gcs_are_young();
2387 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2388 bool is_during_mark = mark_in_progress();
2389
2390 if (is_initial_mark) {
2391 return InitialMark;
2392 } else if (is_during_mark) {
2393 return DuringMark;
2394 } else if (is_young) {
2395 return Normal;
2396 } else {
2397 return Mixed;
2398 }
2399 }
2400
2401 void G1CollectedHeap::collect(GCCause::Cause cause) {
2402 assert_heap_not_locked();
2403
2404 unsigned int gc_count_before;
2405 unsigned int old_marking_count_before;
2406 unsigned int full_gc_count_before;
2407 bool retry_gc;
2408
2409 do {
2410 retry_gc = false;
2411
2412 {
2413 MutexLocker ml(Heap_lock);
2414
2415 // Read the GC count while holding the Heap_lock
2416 gc_count_before = total_collections();
2417 full_gc_count_before = total_full_collections();
2418 old_marking_count_before = _old_marking_cycles_started;
2419 }
2420
2421 if (should_do_concurrent_full_gc(cause)) {
2422 // Schedule an initial-mark evacuation pause that will start a
2423 // concurrent cycle. We're setting word_size to 0 which means that
2424 // we are not requesting a post-GC allocation.
2425 VM_G1IncCollectionPause op(gc_count_before,
2426 0, /* word_size */
2427 true, /* should_initiate_conc_mark */
2428 g1_policy()->max_pause_time_ms(),
2429 cause);
2430 op.set_allocation_context(AllocationContext::current());
2431
2432 VMThread::execute(&op);
2433 if (!op.pause_succeeded()) {
2434 if (old_marking_count_before == _old_marking_cycles_started) {
2435 retry_gc = op.should_retry_gc();
2436 } else {
2437 // A Full GC happened while we were trying to schedule the
2438 // initial-mark GC. No point in starting a new cycle given
2439 // that the whole heap was collected anyway.
2440 }
2441
2442 if (retry_gc) {
2443 if (GC_locker::is_active_and_needs_gc()) {
2444 GC_locker::stall_until_clear();
2445 }
2446 }
2447 }
2448 } else {
2449 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2450 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2451
2452 // Schedule a standard evacuation pause. We're setting word_size
2453 // to 0 which means that we are not requesting a post-GC allocation.
2454 VM_G1IncCollectionPause op(gc_count_before,
2455 0, /* word_size */
2456 false, /* should_initiate_conc_mark */
2457 g1_policy()->max_pause_time_ms(),
2458 cause);
2459 VMThread::execute(&op);
2460 } else {
2461 // Schedule a Full GC.
2462 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2463 VMThread::execute(&op);
2464 }
2465 }
2466 } while (retry_gc);
2467 }
2468
2469 bool G1CollectedHeap::is_in(const void* p) const {
2470 if (_hrm.reserved().contains(p)) {
2471 // Given that we know that p is in the reserved space,
2472 // heap_region_containing_raw() should successfully
2473 // return the containing region.
2474 HeapRegion* hr = heap_region_containing_raw(p);
2475 return hr->is_in(p);
2476 } else {
2477 return false;
2478 }
2479 }
2480
2481 #ifdef ASSERT
2482 bool G1CollectedHeap::is_in_exact(const void* p) const {
2483 bool contains = reserved_region().contains(p);
2484 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2485 if (contains && available) {
2486 return true;
2487 } else {
2488 return false;
2489 }
2490 }
2491 #endif
2492
2493 // Iteration functions.
2494
2495 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2496
2497 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2498 ExtendedOopClosure* _cl;
2499 public:
2500 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2501 bool doHeapRegion(HeapRegion* r) {
2502 if (!r->is_continues_humongous()) {
2503 r->oop_iterate(_cl);
2504 }
2505 return false;
2506 }
2507 };
2508
2509 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2510 IterateOopClosureRegionClosure blk(cl);
2511 heap_region_iterate(&blk);
2512 }
2513
2514 // Iterates an ObjectClosure over all objects within a HeapRegion.
2515
2516 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2517 ObjectClosure* _cl;
2518 public:
2519 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2520 bool doHeapRegion(HeapRegion* r) {
2521 if (!r->is_continues_humongous()) {
2522 r->object_iterate(_cl);
2523 }
2524 return false;
2525 }
2526 };
2527
2528 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2529 IterateObjectClosureRegionClosure blk(cl);
2530 heap_region_iterate(&blk);
2531 }
2532
2533 // Calls a SpaceClosure on a HeapRegion.
2534
2535 class SpaceClosureRegionClosure: public HeapRegionClosure {
2536 SpaceClosure* _cl;
2537 public:
2538 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2539 bool doHeapRegion(HeapRegion* r) {
2540 _cl->do_space(r);
2541 return false;
2542 }
2543 };
2544
2545 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2546 SpaceClosureRegionClosure blk(cl);
2547 heap_region_iterate(&blk);
2548 }
2549
2550 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2551 _hrm.iterate(cl);
2552 }
2553
2554 void
2555 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2556 uint worker_id,
2557 HeapRegionClaimer *hrclaimer,
2558 bool concurrent) const {
2559 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2560 }
2561
2562 // Clear the cached CSet starting regions and (more importantly)
2563 // the time stamps. Called when we reset the GC time stamp.
2564 void G1CollectedHeap::clear_cset_start_regions() {
2565 assert(_worker_cset_start_region != NULL, "sanity");
2566 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2567
2568 int n_queues = MAX2((int)ParallelGCThreads, 1);
2569 for (int i = 0; i < n_queues; i++) {
2570 _worker_cset_start_region[i] = NULL;
2571 _worker_cset_start_region_time_stamp[i] = 0;
2572 }
2573 }
2574
2575 // Given the id of a worker, obtain or calculate a suitable
2576 // starting region for iterating over the current collection set.
2577 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2578 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2579
2580 HeapRegion* result = NULL;
2581 unsigned gc_time_stamp = get_gc_time_stamp();
2582
2583 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2584 // Cached starting region for current worker was set
2585 // during the current pause - so it's valid.
2586 // Note: the cached starting heap region may be NULL
2587 // (when the collection set is empty).
2588 result = _worker_cset_start_region[worker_i];
2589 assert(result == NULL || result->in_collection_set(), "sanity");
2590 return result;
2591 }
2592
2593 // The cached entry was not valid so let's calculate
2594 // a suitable starting heap region for this worker.
2595
2596 // We want the parallel threads to start their collection
2597 // set iteration at different collection set regions to
2598 // avoid contention.
2599 // If we have:
2600 // n collection set regions
2601 // p threads
2602 // Then thread t will start at region floor ((t * n) / p)
2603
2604 result = g1_policy()->collection_set();
2605 uint cs_size = g1_policy()->cset_region_length();
2606 uint active_workers = workers()->active_workers();
2607 assert(UseDynamicNumberOfGCThreads ||
2608 active_workers == workers()->total_workers(),
2609 "Unless dynamic should use total workers");
2610
2611 uint end_ind = (cs_size * worker_i) / active_workers;
2612 uint start_ind = 0;
2613
2614 if (worker_i > 0 &&
2615 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2616 // Previous workers starting region is valid
2617 // so let's iterate from there
2618 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2619 result = _worker_cset_start_region[worker_i - 1];
2620 }
2621
2622 for (uint i = start_ind; i < end_ind; i++) {
2623 result = result->next_in_collection_set();
2624 }
2625
2626 // Note: the calculated starting heap region may be NULL
2627 // (when the collection set is empty).
2628 assert(result == NULL || result->in_collection_set(), "sanity");
2629 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2630 "should be updated only once per pause");
2631 _worker_cset_start_region[worker_i] = result;
2632 OrderAccess::storestore();
2633 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2634 return result;
2635 }
2636
2637 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2638 HeapRegion* r = g1_policy()->collection_set();
2639 while (r != NULL) {
2640 HeapRegion* next = r->next_in_collection_set();
2641 if (cl->doHeapRegion(r)) {
2642 cl->incomplete();
2643 return;
2644 }
2645 r = next;
2646 }
2647 }
2648
2649 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2650 HeapRegionClosure *cl) {
2651 if (r == NULL) {
2652 // The CSet is empty so there's nothing to do.
2653 return;
2654 }
2655
2656 assert(r->in_collection_set(),
2657 "Start region must be a member of the collection set.");
2658 HeapRegion* cur = r;
2659 while (cur != NULL) {
2660 HeapRegion* next = cur->next_in_collection_set();
2661 if (cl->doHeapRegion(cur) && false) {
2662 cl->incomplete();
2663 return;
2664 }
2665 cur = next;
2666 }
2667 cur = g1_policy()->collection_set();
2668 while (cur != r) {
2669 HeapRegion* next = cur->next_in_collection_set();
2670 if (cl->doHeapRegion(cur) && false) {
2671 cl->incomplete();
2672 return;
2673 }
2674 cur = next;
2675 }
2676 }
2677
2678 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2679 HeapRegion* result = _hrm.next_region_in_heap(from);
2680 while (result != NULL && result->is_humongous()) {
2681 result = _hrm.next_region_in_heap(result);
2682 }
2683 return result;
2684 }
2685
2686 Space* G1CollectedHeap::space_containing(const void* addr) const {
2687 return heap_region_containing(addr);
2688 }
2689
2690 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2691 Space* sp = space_containing(addr);
2692 return sp->block_start(addr);
2693 }
2694
2695 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2696 Space* sp = space_containing(addr);
2697 return sp->block_size(addr);
2698 }
2699
2700 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2701 Space* sp = space_containing(addr);
2702 return sp->block_is_obj(addr);
2703 }
2704
2705 bool G1CollectedHeap::supports_tlab_allocation() const {
2706 return true;
2707 }
2708
2709 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2710 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2711 }
2712
2713 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2714 return young_list()->eden_used_bytes();
2715 }
2716
2717 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2718 // must be smaller than the humongous object limit.
2719 size_t G1CollectedHeap::max_tlab_size() const {
2720 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2721 }
2722
2723 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2724 // Return the remaining space in the cur alloc region, but not less than
2725 // the min TLAB size.
2726
2727 // Also, this value can be at most the humongous object threshold,
2728 // since we can't allow tlabs to grow big enough to accommodate
2729 // humongous objects.
2730
2731 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2732 size_t max_tlab = max_tlab_size() * wordSize;
2733 if (hr == NULL) {
2734 return max_tlab;
2735 } else {
2736 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2737 }
2738 }
2739
2740 size_t G1CollectedHeap::max_capacity() const {
2741 return _hrm.reserved().byte_size();
2742 }
2743
2744 jlong G1CollectedHeap::millis_since_last_gc() {
2745 // assert(false, "NYI");
2746 return 0;
2747 }
2748
2749 void G1CollectedHeap::prepare_for_verify() {
2750 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2751 ensure_parsability(false);
2752 }
2753 g1_rem_set()->prepare_for_verify();
2754 }
2755
2756 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2757 VerifyOption vo) {
2758 switch (vo) {
2759 case VerifyOption_G1UsePrevMarking:
2760 return hr->obj_allocated_since_prev_marking(obj);
2761 case VerifyOption_G1UseNextMarking:
2762 return hr->obj_allocated_since_next_marking(obj);
2763 case VerifyOption_G1UseMarkWord:
2764 return false;
2765 default:
2766 ShouldNotReachHere();
2767 }
2768 return false; // keep some compilers happy
2769 }
2770
2771 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2772 switch (vo) {
2773 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2774 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2775 case VerifyOption_G1UseMarkWord: return NULL;
2776 default: ShouldNotReachHere();
2777 }
2778 return NULL; // keep some compilers happy
2779 }
2780
2781 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2782 switch (vo) {
2783 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2784 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2785 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2786 default: ShouldNotReachHere();
2787 }
2788 return false; // keep some compilers happy
2789 }
2790
2791 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2792 switch (vo) {
2793 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2794 case VerifyOption_G1UseNextMarking: return "NTAMS";
2795 case VerifyOption_G1UseMarkWord: return "NONE";
2796 default: ShouldNotReachHere();
2797 }
2798 return NULL; // keep some compilers happy
2799 }
2800
2801 class VerifyRootsClosure: public OopClosure {
2802 private:
2803 G1CollectedHeap* _g1h;
2804 VerifyOption _vo;
2805 bool _failures;
2806 public:
2807 // _vo == UsePrevMarking -> use "prev" marking information,
2808 // _vo == UseNextMarking -> use "next" marking information,
2809 // _vo == UseMarkWord -> use mark word from object header.
2810 VerifyRootsClosure(VerifyOption vo) :
2811 _g1h(G1CollectedHeap::heap()),
2812 _vo(vo),
2813 _failures(false) { }
2814
2815 bool failures() { return _failures; }
2816
2817 template <class T> void do_oop_nv(T* p) {
2818 T heap_oop = oopDesc::load_heap_oop(p);
2819 if (!oopDesc::is_null(heap_oop)) {
2820 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2821 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2822 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2823 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2824 if (_vo == VerifyOption_G1UseMarkWord) {
2825 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2826 }
2827 obj->print_on(gclog_or_tty);
2828 _failures = true;
2829 }
2830 }
2831 }
2832
2833 void do_oop(oop* p) { do_oop_nv(p); }
2834 void do_oop(narrowOop* p) { do_oop_nv(p); }
2835 };
2836
2837 class G1VerifyCodeRootOopClosure: public OopClosure {
2838 G1CollectedHeap* _g1h;
2839 OopClosure* _root_cl;
2840 nmethod* _nm;
2841 VerifyOption _vo;
2842 bool _failures;
2843
2844 template <class T> void do_oop_work(T* p) {
2845 // First verify that this root is live
2846 _root_cl->do_oop(p);
2847
2848 if (!G1VerifyHeapRegionCodeRoots) {
2849 // We're not verifying the code roots attached to heap region.
2850 return;
2851 }
2852
2853 // Don't check the code roots during marking verification in a full GC
2854 if (_vo == VerifyOption_G1UseMarkWord) {
2855 return;
2856 }
2857
2858 // Now verify that the current nmethod (which contains p) is
2859 // in the code root list of the heap region containing the
2860 // object referenced by p.
2861
2862 T heap_oop = oopDesc::load_heap_oop(p);
2863 if (!oopDesc::is_null(heap_oop)) {
2864 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2865
2866 // Now fetch the region containing the object
2867 HeapRegion* hr = _g1h->heap_region_containing(obj);
2868 HeapRegionRemSet* hrrs = hr->rem_set();
2869 // Verify that the strong code root list for this region
2870 // contains the nmethod
2871 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2872 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2873 "from nmethod "PTR_FORMAT" not in strong "
2874 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2875 p, _nm, hr->bottom(), hr->end());
2876 _failures = true;
2877 }
2878 }
2879 }
2880
2881 public:
2882 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2883 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2884
2885 void do_oop(oop* p) { do_oop_work(p); }
2886 void do_oop(narrowOop* p) { do_oop_work(p); }
2887
2888 void set_nmethod(nmethod* nm) { _nm = nm; }
2889 bool failures() { return _failures; }
2890 };
2891
2892 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2893 G1VerifyCodeRootOopClosure* _oop_cl;
2894
2895 public:
2896 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2897 _oop_cl(oop_cl) {}
2898
2899 void do_code_blob(CodeBlob* cb) {
2900 nmethod* nm = cb->as_nmethod_or_null();
2901 if (nm != NULL) {
2902 _oop_cl->set_nmethod(nm);
2903 nm->oops_do(_oop_cl);
2904 }
2905 }
2906 };
2907
2908 class YoungRefCounterClosure : public OopClosure {
2909 G1CollectedHeap* _g1h;
2910 int _count;
2911 public:
2912 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2913 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2914 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2915
2916 int count() { return _count; }
2917 void reset_count() { _count = 0; };
2918 };
2919
2920 class VerifyKlassClosure: public KlassClosure {
2921 YoungRefCounterClosure _young_ref_counter_closure;
2922 OopClosure *_oop_closure;
2923 public:
2924 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2925 void do_klass(Klass* k) {
2926 k->oops_do(_oop_closure);
2927
2928 _young_ref_counter_closure.reset_count();
2929 k->oops_do(&_young_ref_counter_closure);
2930 if (_young_ref_counter_closure.count() > 0) {
2931 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2932 }
2933 }
2934 };
2935
2936 class VerifyLivenessOopClosure: public OopClosure {
2937 G1CollectedHeap* _g1h;
2938 VerifyOption _vo;
2939 public:
2940 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2941 _g1h(g1h), _vo(vo)
2942 { }
2943 void do_oop(narrowOop *p) { do_oop_work(p); }
2944 void do_oop( oop *p) { do_oop_work(p); }
2945
2946 template <class T> void do_oop_work(T *p) {
2947 oop obj = oopDesc::load_decode_heap_oop(p);
2948 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2949 "Dead object referenced by a not dead object");
2950 }
2951 };
2952
2953 class VerifyObjsInRegionClosure: public ObjectClosure {
2954 private:
2955 G1CollectedHeap* _g1h;
2956 size_t _live_bytes;
2957 HeapRegion *_hr;
2958 VerifyOption _vo;
2959 public:
2960 // _vo == UsePrevMarking -> use "prev" marking information,
2961 // _vo == UseNextMarking -> use "next" marking information,
2962 // _vo == UseMarkWord -> use mark word from object header.
2963 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2964 : _live_bytes(0), _hr(hr), _vo(vo) {
2965 _g1h = G1CollectedHeap::heap();
2966 }
2967 void do_object(oop o) {
2968 VerifyLivenessOopClosure isLive(_g1h, _vo);
2969 assert(o != NULL, "Huh?");
2970 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2971 // If the object is alive according to the mark word,
2972 // then verify that the marking information agrees.
2973 // Note we can't verify the contra-positive of the
2974 // above: if the object is dead (according to the mark
2975 // word), it may not be marked, or may have been marked
2976 // but has since became dead, or may have been allocated
2977 // since the last marking.
2978 if (_vo == VerifyOption_G1UseMarkWord) {
2979 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2980 }
2981
2982 o->oop_iterate_no_header(&isLive);
2983 if (!_hr->obj_allocated_since_prev_marking(o)) {
2984 size_t obj_size = o->size(); // Make sure we don't overflow
2985 _live_bytes += (obj_size * HeapWordSize);
2986 }
2987 }
2988 }
2989 size_t live_bytes() { return _live_bytes; }
2990 };
2991
2992 class PrintObjsInRegionClosure : public ObjectClosure {
2993 HeapRegion *_hr;
2994 G1CollectedHeap *_g1;
2995 public:
2996 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2997 _g1 = G1CollectedHeap::heap();
2998 };
2999
3000 void do_object(oop o) {
3001 if (o != NULL) {
3002 HeapWord *start = (HeapWord *) o;
3003 size_t word_sz = o->size();
3004 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3005 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3006 (void*) o, word_sz,
3007 _g1->isMarkedPrev(o),
3008 _g1->isMarkedNext(o),
3009 _hr->obj_allocated_since_prev_marking(o));
3010 HeapWord *end = start + word_sz;
3011 HeapWord *cur;
3012 int *val;
3013 for (cur = start; cur < end; cur++) {
3014 val = (int *) cur;
3015 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3016 }
3017 }
3018 }
3019 };
3020
3021 class VerifyRegionClosure: public HeapRegionClosure {
3022 private:
3023 bool _par;
3024 VerifyOption _vo;
3025 bool _failures;
3026 public:
3027 // _vo == UsePrevMarking -> use "prev" marking information,
3028 // _vo == UseNextMarking -> use "next" marking information,
3029 // _vo == UseMarkWord -> use mark word from object header.
3030 VerifyRegionClosure(bool par, VerifyOption vo)
3031 : _par(par),
3032 _vo(vo),
3033 _failures(false) {}
3034
3035 bool failures() {
3036 return _failures;
3037 }
3038
3039 bool doHeapRegion(HeapRegion* r) {
3040 if (!r->is_continues_humongous()) {
3041 bool failures = false;
3042 r->verify(_vo, &failures);
3043 if (failures) {
3044 _failures = true;
3045 } else {
3046 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3047 r->object_iterate(¬_dead_yet_cl);
3048 if (_vo != VerifyOption_G1UseNextMarking) {
3049 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3050 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3051 "max_live_bytes "SIZE_FORMAT" "
3052 "< calculated "SIZE_FORMAT,
3053 r->bottom(), r->end(),
3054 r->max_live_bytes(),
3055 not_dead_yet_cl.live_bytes());
3056 _failures = true;
3057 }
3058 } else {
3059 // When vo == UseNextMarking we cannot currently do a sanity
3060 // check on the live bytes as the calculation has not been
3061 // finalized yet.
3062 }
3063 }
3064 }
3065 return false; // stop the region iteration if we hit a failure
3066 }
3067 };
3068
3069 // This is the task used for parallel verification of the heap regions
3070
3071 class G1ParVerifyTask: public AbstractGangTask {
3072 private:
3073 G1CollectedHeap* _g1h;
3074 VerifyOption _vo;
3075 bool _failures;
3076 HeapRegionClaimer _hrclaimer;
3077
3078 public:
3079 // _vo == UsePrevMarking -> use "prev" marking information,
3080 // _vo == UseNextMarking -> use "next" marking information,
3081 // _vo == UseMarkWord -> use mark word from object header.
3082 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3083 AbstractGangTask("Parallel verify task"),
3084 _g1h(g1h),
3085 _vo(vo),
3086 _failures(false),
3087 _hrclaimer(g1h->workers()->active_workers()) {}
3088
3089 bool failures() {
3090 return _failures;
3091 }
3092
3093 void work(uint worker_id) {
3094 HandleMark hm;
3095 VerifyRegionClosure blk(true, _vo);
3096 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3097 if (blk.failures()) {
3098 _failures = true;
3099 }
3100 }
3101 };
3102
3103 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3104 if (SafepointSynchronize::is_at_safepoint()) {
3105 assert(Thread::current()->is_VM_thread(),
3106 "Expected to be executed serially by the VM thread at this point");
3107
3108 if (!silent) { gclog_or_tty->print("Roots "); }
3109 VerifyRootsClosure rootsCl(vo);
3110 VerifyKlassClosure klassCl(this, &rootsCl);
3111 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3112
3113 // We apply the relevant closures to all the oops in the
3114 // system dictionary, class loader data graph, the string table
3115 // and the nmethods in the code cache.
3116 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3117 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3118
3119 process_all_roots(true, // activate StrongRootsScope
3120 SO_AllCodeCache, // roots scanning options
3121 &rootsCl,
3122 &cldCl,
3123 &blobsCl);
3124
3125 bool failures = rootsCl.failures() || codeRootsCl.failures();
3126
3127 if (vo != VerifyOption_G1UseMarkWord) {
3128 // If we're verifying during a full GC then the region sets
3129 // will have been torn down at the start of the GC. Therefore
3130 // verifying the region sets will fail. So we only verify
3131 // the region sets when not in a full GC.
3132 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3133 verify_region_sets();
3134 }
3135
3136 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3137 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3138
3139 G1ParVerifyTask task(this, vo);
3140 assert(UseDynamicNumberOfGCThreads ||
3141 workers()->active_workers() == workers()->total_workers(),
3142 "If not dynamic should be using all the workers");
3143 int n_workers = workers()->active_workers();
3144 set_par_threads(n_workers);
3145 workers()->run_task(&task);
3146 set_par_threads(0);
3147 if (task.failures()) {
3148 failures = true;
3149 }
3150
3151 } else {
3152 VerifyRegionClosure blk(false, vo);
3153 heap_region_iterate(&blk);
3154 if (blk.failures()) {
3155 failures = true;
3156 }
3157 }
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
3492 DirtyCardQueue _dcq;
3493
3494 bool humongous_region_is_candidate(uint index) {
3495 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3496 assert(region->is_starts_humongous(), "Must start a humongous object");
3497 HeapRegionRemSet* const rset = region->rem_set();
3498 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3499 return !oop(region->bottom())->is_objArray() &&
3500 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3501 (!allow_stale_refs && rset->is_empty()));
3502 }
3503
3504 public:
3505 RegisterHumongousWithInCSetFastTestClosure()
3506 : _total_humongous(0),
3507 _candidate_humongous(0),
3508 _dcq(&JavaThread::dirty_card_queue_set()) {
3509 }
3510
3511 virtual bool doHeapRegion(HeapRegion* r) {
3512 if (!r->is_starts_humongous()) {
3513 return false;
3514 }
3515 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3516
3517 uint region_idx = r->hrm_index();
3518 bool is_candidate = humongous_region_is_candidate(region_idx);
3519 // Is_candidate already filters out humongous object with large remembered sets.
3520 // If we have a humongous object with a few remembered sets, we simply flush these
3521 // remembered set entries into the DCQS. That will result in automatic
3522 // re-evaluation of their remembered set entries during the following evacuation
3523 // phase.
3524 if (is_candidate) {
3525 if (!r->rem_set()->is_empty()) {
3526 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3527 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3528 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3529 HeapRegionRemSetIterator hrrs(r->rem_set());
3530 size_t card_index;
3531 while (hrrs.has_next(card_index)) {
3532 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3533 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3534 *card_ptr = CardTableModRefBS::dirty_card_val();
3535 _dcq.enqueue(card_ptr);
3536 }
3537 }
3538 r->rem_set()->clear_locked();
3539 }
3540 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3541 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3542 _candidate_humongous++;
3543 }
3544 _total_humongous++;
3545
3546 return false;
3547 }
3548
3549 size_t total_humongous() const { return _total_humongous; }
3550 size_t candidate_humongous() const { return _candidate_humongous; }
3551
3552 void flush_rem_set_entries() { _dcq.flush(); }
3553 };
3554
3555 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3556 if (!G1EagerReclaimHumongousObjects) {
3557 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3558 return;
3559 }
3560 double time = os::elapsed_counter();
3561
3562 RegisterHumongousWithInCSetFastTestClosure cl;
3563 heap_region_iterate(&cl);
3564
3565 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3566 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3567 cl.total_humongous(),
3568 cl.candidate_humongous());
3569 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3570
3571 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3572 clear_humongous_is_live_table();
3573 }
3574
3575 // Finally flush all remembered set entries to re-check into the global DCQS.
3576 cl.flush_rem_set_entries();
3577 }
3578
3579 void
3580 G1CollectedHeap::setup_surviving_young_words() {
3581 assert(_surviving_young_words == NULL, "pre-condition");
3582 uint array_length = g1_policy()->young_cset_region_length();
3583 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3584 if (_surviving_young_words == NULL) {
3585 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3586 "Not enough space for young surv words summary.");
3587 }
3588 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3589 #ifdef ASSERT
3590 for (uint i = 0; i < array_length; ++i) {
3591 assert( _surviving_young_words[i] == 0, "memset above" );
3592 }
3593 #endif // !ASSERT
3594 }
3595
3596 void
3597 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3598 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3599 uint array_length = g1_policy()->young_cset_region_length();
3600 for (uint i = 0; i < array_length; ++i) {
3601 _surviving_young_words[i] += surv_young_words[i];
3602 }
3603 }
3604
3605 void
3606 G1CollectedHeap::cleanup_surviving_young_words() {
3607 guarantee( _surviving_young_words != NULL, "pre-condition" );
3608 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3609 _surviving_young_words = NULL;
3610 }
3611
3612 #ifdef ASSERT
3613 class VerifyCSetClosure: public HeapRegionClosure {
3614 public:
3615 bool doHeapRegion(HeapRegion* hr) {
3616 // Here we check that the CSet region's RSet is ready for parallel
3617 // iteration. The fields that we'll verify are only manipulated
3618 // when the region is part of a CSet and is collected. Afterwards,
3619 // we reset these fields when we clear the region's RSet (when the
3620 // region is freed) so they are ready when the region is
3621 // re-allocated. The only exception to this is if there's an
3622 // evacuation failure and instead of freeing the region we leave
3623 // it in the heap. In that case, we reset these fields during
3624 // evacuation failure handling.
3625 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3626
3627 // Here's a good place to add any other checks we'd like to
3628 // perform on CSet regions.
3629 return false;
3630 }
3631 };
3632 #endif // ASSERT
3633
3634 #if TASKQUEUE_STATS
3635 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3636 st->print_raw_cr("GC Task Stats");
3637 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3638 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3639 }
3640
3641 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3642 print_taskqueue_stats_hdr(st);
3643
3644 TaskQueueStats totals;
3645 const int n = workers()->total_workers();
3646 for (int i = 0; i < n; ++i) {
3647 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3648 totals += task_queue(i)->stats;
3649 }
3650 st->print_raw("tot "); totals.print(st); st->cr();
3651
3652 DEBUG_ONLY(totals.verify());
3653 }
3654
3655 void G1CollectedHeap::reset_taskqueue_stats() {
3656 const int n = workers()->total_workers();
3657 for (int i = 0; i < n; ++i) {
3658 task_queue(i)->stats.reset();
3659 }
3660 }
3661 #endif // TASKQUEUE_STATS
3662
3663 void G1CollectedHeap::log_gc_header() {
3664 if (!G1Log::fine()) {
3665 return;
3666 }
3667
3668 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3669
3670 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3671 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3672 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3673
3674 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3675 }
3676
3677 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3678 if (!G1Log::fine()) {
3679 return;
3680 }
3681
3682 if (G1Log::finer()) {
3683 if (evacuation_failed()) {
3684 gclog_or_tty->print(" (to-space exhausted)");
3685 }
3686 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3687 g1_policy()->phase_times()->note_gc_end();
3688 g1_policy()->phase_times()->print(pause_time_sec);
3689 g1_policy()->print_detailed_heap_transition();
3690 } else {
3691 if (evacuation_failed()) {
3692 gclog_or_tty->print("--");
3693 }
3694 g1_policy()->print_heap_transition();
3695 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3696 }
3697 gclog_or_tty->flush();
3698 }
3699
3700 bool
3701 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3702 assert_at_safepoint(true /* should_be_vm_thread */);
3703 guarantee(!is_gc_active(), "collection is not reentrant");
3704
3705 if (GC_locker::check_active_before_gc()) {
3706 return false;
3707 }
3708
3709 _gc_timer_stw->register_gc_start();
3710
3711 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3712
3713 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3714 ResourceMark rm;
3715
3716 print_heap_before_gc();
3717 trace_heap_before_gc(_gc_tracer_stw);
3718
3719 verify_region_sets_optional();
3720 verify_dirty_young_regions();
3721
3722 // This call will decide whether this pause is an initial-mark
3723 // pause. If it is, during_initial_mark_pause() will return true
3724 // for the duration of this pause.
3725 g1_policy()->decide_on_conc_mark_initiation();
3726
3727 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3728 assert(!g1_policy()->during_initial_mark_pause() ||
3729 g1_policy()->gcs_are_young(), "sanity");
3730
3731 // We also do not allow mixed GCs during marking.
3732 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3733
3734 // Record whether this pause is an initial mark. When the current
3735 // thread has completed its logging output and it's safe to signal
3736 // the CM thread, the flag's value in the policy has been reset.
3737 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3738
3739 // Inner scope for scope based logging, timers, and stats collection
3740 {
3741 EvacuationInfo evacuation_info;
3742
3743 if (g1_policy()->during_initial_mark_pause()) {
3744 // We are about to start a marking cycle, so we increment the
3745 // full collection counter.
3746 increment_old_marking_cycles_started();
3747 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3748 }
3749
3750 _gc_tracer_stw->report_yc_type(yc_type());
3751
3752 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3753
3754 int active_workers = workers()->active_workers();
3755 double pause_start_sec = os::elapsedTime();
3756 g1_policy()->phase_times()->note_gc_start(active_workers);
3757 log_gc_header();
3758
3759 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3760 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3761
3762 // If the secondary_free_list is not empty, append it to the
3763 // free_list. No need to wait for the cleanup operation to finish;
3764 // the region allocation code will check the secondary_free_list
3765 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3766 // set, skip this step so that the region allocation code has to
3767 // get entries from the secondary_free_list.
3768 if (!G1StressConcRegionFreeing) {
3769 append_secondary_free_list_if_not_empty_with_lock();
3770 }
3771
3772 assert(check_young_list_well_formed(), "young list should be well formed");
3773
3774 // Don't dynamically change the number of GC threads this early. A value of
3775 // 0 is used to indicate serial work. When parallel work is done,
3776 // it will be set.
3777
3778 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3779 IsGCActiveMark x;
3780
3781 gc_prologue(false);
3782 increment_total_collections(false /* full gc */);
3783 increment_gc_time_stamp();
3784
3785 verify_before_gc();
3786
3787 check_bitmaps("GC Start");
3788
3789 COMPILER2_PRESENT(DerivedPointerTable::clear());
3790
3791 // Please see comment in g1CollectedHeap.hpp and
3792 // G1CollectedHeap::ref_processing_init() to see how
3793 // reference processing currently works in G1.
3794
3795 // Enable discovery in the STW reference processor
3796 ref_processor_stw()->enable_discovery();
3797
3798 {
3799 // We want to temporarily turn off discovery by the
3800 // CM ref processor, if necessary, and turn it back on
3801 // on again later if we do. Using a scoped
3802 // NoRefDiscovery object will do this.
3803 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3804
3805 // Forget the current alloc region (we might even choose it to be part
3806 // of the collection set!).
3807 _allocator->release_mutator_alloc_region();
3808
3809 // We should call this after we retire the mutator alloc
3810 // region(s) so that all the ALLOC / RETIRE events are generated
3811 // before the start GC event.
3812 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3813
3814 // This timing is only used by the ergonomics to handle our pause target.
3815 // It is unclear why this should not include the full pause. We will
3816 // investigate this in CR 7178365.
3817 //
3818 // Preserving the old comment here if that helps the investigation:
3819 //
3820 // The elapsed time induced by the start time below deliberately elides
3821 // the possible verification above.
3822 double sample_start_time_sec = os::elapsedTime();
3823
3824 #if YOUNG_LIST_VERBOSE
3825 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3826 _young_list->print();
3827 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3828 #endif // YOUNG_LIST_VERBOSE
3829
3830 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3831
3832 double scan_wait_start = os::elapsedTime();
3833 // We have to wait until the CM threads finish scanning the
3834 // root regions as it's the only way to ensure that all the
3835 // objects on them have been correctly scanned before we start
3836 // moving them during the GC.
3837 bool waited = _cm->root_regions()->wait_until_scan_finished();
3838 double wait_time_ms = 0.0;
3839 if (waited) {
3840 double scan_wait_end = os::elapsedTime();
3841 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3842 }
3843 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3844
3845 #if YOUNG_LIST_VERBOSE
3846 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3847 _young_list->print();
3848 #endif // YOUNG_LIST_VERBOSE
3849
3850 if (g1_policy()->during_initial_mark_pause()) {
3851 concurrent_mark()->checkpointRootsInitialPre();
3852 }
3853
3854 #if YOUNG_LIST_VERBOSE
3855 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3856 _young_list->print();
3857 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3858 #endif // YOUNG_LIST_VERBOSE
3859
3860 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3861
3862 register_humongous_regions_with_in_cset_fast_test();
3863
3864 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3865
3866 _cm->note_start_of_gc();
3867 // We should not verify the per-thread SATB buffers given that
3868 // we have not filtered them yet (we'll do so during the
3869 // GC). We also call this after finalize_cset() to
3870 // ensure that the CSet has been finalized.
3871 _cm->verify_no_cset_oops(true /* verify_stacks */,
3872 true /* verify_enqueued_buffers */,
3873 false /* verify_thread_buffers */,
3874 true /* verify_fingers */);
3875
3876 if (_hr_printer.is_active()) {
3877 HeapRegion* hr = g1_policy()->collection_set();
3878 while (hr != NULL) {
3879 _hr_printer.cset(hr);
3880 hr = hr->next_in_collection_set();
3881 }
3882 }
3883
3884 #ifdef ASSERT
3885 VerifyCSetClosure cl;
3886 collection_set_iterate(&cl);
3887 #endif // ASSERT
3888
3889 setup_surviving_young_words();
3890
3891 // Initialize the GC alloc regions.
3892 _allocator->init_gc_alloc_regions(evacuation_info);
3893
3894 // Actually do the work...
3895 evacuate_collection_set(evacuation_info);
3896
3897 // We do this to mainly verify the per-thread SATB buffers
3898 // (which have been filtered by now) since we didn't verify
3899 // them earlier. No point in re-checking the stacks / enqueued
3900 // buffers given that the CSet has not changed since last time
3901 // we checked.
3902 _cm->verify_no_cset_oops(false /* verify_stacks */,
3903 false /* verify_enqueued_buffers */,
3904 true /* verify_thread_buffers */,
3905 true /* verify_fingers */);
3906
3907 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3908
3909 eagerly_reclaim_humongous_regions();
3910
3911 g1_policy()->clear_collection_set();
3912
3913 cleanup_surviving_young_words();
3914
3915 // Start a new incremental collection set for the next pause.
3916 g1_policy()->start_incremental_cset_building();
3917
3918 clear_cset_fast_test();
3919
3920 _young_list->reset_sampled_info();
3921
3922 // Don't check the whole heap at this point as the
3923 // GC alloc regions from this pause have been tagged
3924 // as survivors and moved on to the survivor list.
3925 // Survivor regions will fail the !is_young() check.
3926 assert(check_young_list_empty(false /* check_heap */),
3927 "young list should be empty");
3928
3929 #if YOUNG_LIST_VERBOSE
3930 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3931 _young_list->print();
3932 #endif // YOUNG_LIST_VERBOSE
3933
3934 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3935 _young_list->first_survivor_region(),
3936 _young_list->last_survivor_region());
3937
3938 _young_list->reset_auxilary_lists();
3939
3940 if (evacuation_failed()) {
3941 _allocator->set_used(recalculate_used());
3942 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3943 for (uint i = 0; i < n_queues; i++) {
3944 if (_evacuation_failed_info_array[i].has_failed()) {
3945 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3946 }
3947 }
3948 } else {
3949 // The "used" of the the collection set have already been subtracted
3950 // when they were freed. Add in the bytes evacuated.
3951 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3952 }
3953
3954 if (g1_policy()->during_initial_mark_pause()) {
3955 // We have to do this before we notify the CM threads that
3956 // they can start working to make sure that all the
3957 // appropriate initialization is done on the CM object.
3958 concurrent_mark()->checkpointRootsInitialPost();
3959 set_marking_started();
3960 // Note that we don't actually trigger the CM thread at
3961 // this point. We do that later when we're sure that
3962 // the current thread has completed its logging output.
3963 }
3964
3965 allocate_dummy_regions();
3966
3967 #if YOUNG_LIST_VERBOSE
3968 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3969 _young_list->print();
3970 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3971 #endif // YOUNG_LIST_VERBOSE
3972
3973 _allocator->init_mutator_alloc_region();
3974
3975 {
3976 size_t expand_bytes = g1_policy()->expansion_amount();
3977 if (expand_bytes > 0) {
3978 size_t bytes_before = capacity();
3979 // No need for an ergo verbose message here,
3980 // expansion_amount() does this when it returns a value > 0.
3981 if (!expand(expand_bytes)) {
3982 // We failed to expand the heap. Cannot do anything about it.
3983 }
3984 }
3985 }
3986
3987 // We redo the verification but now wrt to the new CSet which
3988 // has just got initialized after the previous CSet was freed.
3989 _cm->verify_no_cset_oops(true /* verify_stacks */,
3990 true /* verify_enqueued_buffers */,
3991 true /* verify_thread_buffers */,
3992 true /* verify_fingers */);
3993 _cm->note_end_of_gc();
3994
3995 // This timing is only used by the ergonomics to handle our pause target.
3996 // It is unclear why this should not include the full pause. We will
3997 // investigate this in CR 7178365.
3998 double sample_end_time_sec = os::elapsedTime();
3999 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4000 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4001
4002 MemoryService::track_memory_usage();
4003
4004 // In prepare_for_verify() below we'll need to scan the deferred
4005 // update buffers to bring the RSets up-to-date if
4006 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4007 // the update buffers we'll probably need to scan cards on the
4008 // regions we just allocated to (i.e., the GC alloc
4009 // regions). However, during the last GC we called
4010 // set_saved_mark() on all the GC alloc regions, so card
4011 // scanning might skip the [saved_mark_word()...top()] area of
4012 // those regions (i.e., the area we allocated objects into
4013 // during the last GC). But it shouldn't. Given that
4014 // saved_mark_word() is conditional on whether the GC time stamp
4015 // on the region is current or not, by incrementing the GC time
4016 // stamp here we invalidate all the GC time stamps on all the
4017 // regions and saved_mark_word() will simply return top() for
4018 // all the regions. This is a nicer way of ensuring this rather
4019 // than iterating over the regions and fixing them. In fact, the
4020 // GC time stamp increment here also ensures that
4021 // saved_mark_word() will return top() between pauses, i.e.,
4022 // during concurrent refinement. So we don't need the
4023 // is_gc_active() check to decided which top to use when
4024 // scanning cards (see CR 7039627).
4025 increment_gc_time_stamp();
4026
4027 verify_after_gc();
4028 check_bitmaps("GC End");
4029
4030 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4031 ref_processor_stw()->verify_no_references_recorded();
4032
4033 // CM reference discovery will be re-enabled if necessary.
4034 }
4035
4036 // We should do this after we potentially expand the heap so
4037 // that all the COMMIT events are generated before the end GC
4038 // event, and after we retire the GC alloc regions so that all
4039 // RETIRE events are generated before the end GC event.
4040 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4041
4042 #ifdef TRACESPINNING
4043 ParallelTaskTerminator::print_termination_counts();
4044 #endif
4045
4046 gc_epilogue(false);
4047 }
4048
4049 // Print the remainder of the GC log output.
4050 log_gc_footer(os::elapsedTime() - pause_start_sec);
4051
4052 // It is not yet to safe to tell the concurrent mark to
4053 // start as we have some optional output below. We don't want the
4054 // output from the concurrent mark thread interfering with this
4055 // logging output either.
4056
4057 _hrm.verify_optional();
4058 verify_region_sets_optional();
4059
4060 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4061 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4062
4063 print_heap_after_gc();
4064 trace_heap_after_gc(_gc_tracer_stw);
4065
4066 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4067 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4068 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4069 // before any GC notifications are raised.
4070 g1mm()->update_sizes();
4071
4072 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4073 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4074 _gc_timer_stw->register_gc_end();
4075 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4076 }
4077 // It should now be safe to tell the concurrent mark thread to start
4078 // without its logging output interfering with the logging output
4079 // that came from the pause.
4080
4081 if (should_start_conc_mark) {
4082 // CAUTION: after the doConcurrentMark() call below,
4083 // the concurrent marking thread(s) could be running
4084 // concurrently with us. Make sure that anything after
4085 // this point does not assume that we are the only GC thread
4086 // running. Note: of course, the actual marking work will
4087 // not start until the safepoint itself is released in
4088 // SuspendibleThreadSet::desynchronize().
4089 doConcurrentMark();
4090 }
4091
4092 return true;
4093 }
4094
4095 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4096 _drain_in_progress = false;
4097 set_evac_failure_closure(cl);
4098 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4099 }
4100
4101 void G1CollectedHeap::finalize_for_evac_failure() {
4102 assert(_evac_failure_scan_stack != NULL &&
4103 _evac_failure_scan_stack->length() == 0,
4104 "Postcondition");
4105 assert(!_drain_in_progress, "Postcondition");
4106 delete _evac_failure_scan_stack;
4107 _evac_failure_scan_stack = NULL;
4108 }
4109
4110 void G1CollectedHeap::remove_self_forwarding_pointers() {
4111 double remove_self_forwards_start = os::elapsedTime();
4112
4113 set_par_threads();
4114 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4115 workers()->run_task(&rsfp_task);
4116 set_par_threads(0);
4117
4118 // Now restore saved marks, if any.
4119 assert(_objs_with_preserved_marks.size() ==
4120 _preserved_marks_of_objs.size(), "Both or none.");
4121 while (!_objs_with_preserved_marks.is_empty()) {
4122 oop obj = _objs_with_preserved_marks.pop();
4123 markOop m = _preserved_marks_of_objs.pop();
4124 obj->set_mark(m);
4125 }
4126 _objs_with_preserved_marks.clear(true);
4127 _preserved_marks_of_objs.clear(true);
4128
4129 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4130 }
4131
4132 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4133 _evac_failure_scan_stack->push(obj);
4134 }
4135
4136 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4137 assert(_evac_failure_scan_stack != NULL, "precondition");
4138
4139 while (_evac_failure_scan_stack->length() > 0) {
4140 oop obj = _evac_failure_scan_stack->pop();
4141 _evac_failure_closure->set_region(heap_region_containing(obj));
4142 obj->oop_iterate_backwards(_evac_failure_closure);
4143 }
4144 }
4145
4146 oop
4147 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4148 oop old) {
4149 assert(obj_in_cs(old),
4150 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4151 (HeapWord*) old));
4152 markOop m = old->mark();
4153 oop forward_ptr = old->forward_to_atomic(old);
4154 if (forward_ptr == NULL) {
4155 // Forward-to-self succeeded.
4156 assert(_par_scan_state != NULL, "par scan state");
4157 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4158 uint queue_num = _par_scan_state->queue_num();
4159
4160 _evacuation_failed = true;
4161 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4162 if (_evac_failure_closure != cl) {
4163 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4164 assert(!_drain_in_progress,
4165 "Should only be true while someone holds the lock.");
4166 // Set the global evac-failure closure to the current thread's.
4167 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4168 set_evac_failure_closure(cl);
4169 // Now do the common part.
4170 handle_evacuation_failure_common(old, m);
4171 // Reset to NULL.
4172 set_evac_failure_closure(NULL);
4173 } else {
4174 // The lock is already held, and this is recursive.
4175 assert(_drain_in_progress, "This should only be the recursive case.");
4176 handle_evacuation_failure_common(old, m);
4177 }
4178 return old;
4179 } else {
4180 // Forward-to-self failed. Either someone else managed to allocate
4181 // space for this object (old != forward_ptr) or they beat us in
4182 // self-forwarding it (old == forward_ptr).
4183 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4184 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4185 "should not be in the CSet",
4186 (HeapWord*) old, (HeapWord*) forward_ptr));
4187 return forward_ptr;
4188 }
4189 }
4190
4191 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4192 preserve_mark_if_necessary(old, m);
4193
4194 HeapRegion* r = heap_region_containing(old);
4195 if (!r->evacuation_failed()) {
4196 r->set_evacuation_failed(true);
4197 _hr_printer.evac_failure(r);
4198 }
4199
4200 push_on_evac_failure_scan_stack(old);
4201
4202 if (!_drain_in_progress) {
4203 // prevent recursion in copy_to_survivor_space()
4204 _drain_in_progress = true;
4205 drain_evac_failure_scan_stack();
4206 _drain_in_progress = false;
4207 }
4208 }
4209
4210 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4211 assert(evacuation_failed(), "Oversaving!");
4212 // We want to call the "for_promotion_failure" version only in the
4213 // case of a promotion failure.
4214 if (m->must_be_preserved_for_promotion_failure(obj)) {
4215 _objs_with_preserved_marks.push(obj);
4216 _preserved_marks_of_objs.push(m);
4217 }
4218 }
4219
4220 void G1ParCopyHelper::mark_object(oop obj) {
4221 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4222
4223 // We know that the object is not moving so it's safe to read its size.
4224 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4225 }
4226
4227 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4228 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4229 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4230 assert(from_obj != to_obj, "should not be self-forwarded");
4231
4232 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4233 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4234
4235 // The object might be in the process of being copied by another
4236 // worker so we cannot trust that its to-space image is
4237 // well-formed. So we have to read its size from its from-space
4238 // image which we know should not be changing.
4239 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4240 }
4241
4242 template <class T>
4243 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4244 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4245 _scanned_klass->record_modified_oops();
4246 }
4247 }
4248
4249 template <G1Barrier barrier, G1Mark do_mark_object>
4250 template <class T>
4251 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4252 T heap_oop = oopDesc::load_heap_oop(p);
4253
4254 if (oopDesc::is_null(heap_oop)) {
4255 return;
4256 }
4257
4258 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4259
4260 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4261
4262 const InCSetState state = _g1->in_cset_state(obj);
4263 if (state.is_in_cset()) {
4264 oop forwardee;
4265 markOop m = obj->mark();
4266 if (m->is_marked()) {
4267 forwardee = (oop) m->decode_pointer();
4268 } else {
4269 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4270 }
4271 assert(forwardee != NULL, "forwardee should not be NULL");
4272 oopDesc::encode_store_heap_oop(p, forwardee);
4273 if (do_mark_object != G1MarkNone && forwardee != obj) {
4274 // If the object is self-forwarded we don't need to explicitly
4275 // mark it, the evacuation failure protocol will do so.
4276 mark_forwarded_object(obj, forwardee);
4277 }
4278
4279 if (barrier == G1BarrierKlass) {
4280 do_klass_barrier(p, forwardee);
4281 }
4282 } else {
4283 if (state.is_humongous()) {
4284 _g1->set_humongous_is_live(obj);
4285 }
4286 // The object is not in collection set. If we're a root scanning
4287 // closure during an initial mark pause then attempt to mark the object.
4288 if (do_mark_object == G1MarkFromRoot) {
4289 mark_object(obj);
4290 }
4291 }
4292
4293 if (barrier == G1BarrierEvac) {
4294 _par_scan_state->update_rs(_from, p, _worker_id);
4295 }
4296 }
4297
4298 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4299 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4300
4301 class G1ParEvacuateFollowersClosure : public VoidClosure {
4302 protected:
4303 G1CollectedHeap* _g1h;
4304 G1ParScanThreadState* _par_scan_state;
4305 RefToScanQueueSet* _queues;
4306 ParallelTaskTerminator* _terminator;
4307
4308 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4309 RefToScanQueueSet* queues() { return _queues; }
4310 ParallelTaskTerminator* terminator() { return _terminator; }
4311
4312 public:
4313 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4314 G1ParScanThreadState* par_scan_state,
4315 RefToScanQueueSet* queues,
4316 ParallelTaskTerminator* terminator)
4317 : _g1h(g1h), _par_scan_state(par_scan_state),
4318 _queues(queues), _terminator(terminator) {}
4319
4320 void do_void();
4321
4322 private:
4323 inline bool offer_termination();
4324 };
4325
4326 bool G1ParEvacuateFollowersClosure::offer_termination() {
4327 G1ParScanThreadState* const pss = par_scan_state();
4328 pss->start_term_time();
4329 const bool res = terminator()->offer_termination();
4330 pss->end_term_time();
4331 return res;
4332 }
4333
4334 void G1ParEvacuateFollowersClosure::do_void() {
4335 G1ParScanThreadState* const pss = par_scan_state();
4336 pss->trim_queue();
4337 do {
4338 pss->steal_and_trim_queue(queues());
4339 } while (!offer_termination());
4340 }
4341
4342 class G1KlassScanClosure : public KlassClosure {
4343 G1ParCopyHelper* _closure;
4344 bool _process_only_dirty;
4345 int _count;
4346 public:
4347 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4348 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4349 void do_klass(Klass* klass) {
4350 // If the klass has not been dirtied we know that there's
4351 // no references into the young gen and we can skip it.
4352 if (!_process_only_dirty || klass->has_modified_oops()) {
4353 // Clean the klass since we're going to scavenge all the metadata.
4354 klass->clear_modified_oops();
4355
4356 // Tell the closure that this klass is the Klass to scavenge
4357 // and is the one to dirty if oops are left pointing into the young gen.
4358 _closure->set_scanned_klass(klass);
4359
4360 klass->oops_do(_closure);
4361
4362 _closure->set_scanned_klass(NULL);
4363 }
4364 _count++;
4365 }
4366 };
4367
4368 class G1CodeBlobClosure : public CodeBlobClosure {
4369 class HeapRegionGatheringOopClosure : public OopClosure {
4370 G1CollectedHeap* _g1h;
4371 OopClosure* _work;
4372 nmethod* _nm;
4373
4374 template <typename T>
4375 void do_oop_work(T* p) {
4376 _work->do_oop(p);
4377 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4378 if (!oopDesc::is_null(oop_or_narrowoop)) {
4379 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4380 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4381 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");
4382 hr->add_strong_code_root(_nm);
4383 }
4384 }
4385
4386 public:
4387 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4388
4389 void do_oop(oop* o) {
4390 do_oop_work(o);
4391 }
4392
4393 void do_oop(narrowOop* o) {
4394 do_oop_work(o);
4395 }
4396
4397 void set_nm(nmethod* nm) {
4398 _nm = nm;
4399 }
4400 };
4401
4402 HeapRegionGatheringOopClosure _oc;
4403 public:
4404 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4405
4406 void do_code_blob(CodeBlob* cb) {
4407 nmethod* nm = cb->as_nmethod_or_null();
4408 if (nm != NULL) {
4409 if (!nm->test_set_oops_do_mark()) {
4410 _oc.set_nm(nm);
4411 nm->oops_do(&_oc);
4412 nm->fix_oop_relocations();
4413 }
4414 }
4415 }
4416 };
4417
4418 class G1ParTask : public AbstractGangTask {
4419 protected:
4420 G1CollectedHeap* _g1h;
4421 RefToScanQueueSet *_queues;
4422 ParallelTaskTerminator _terminator;
4423 uint _n_workers;
4424
4425 Mutex _stats_lock;
4426 Mutex* stats_lock() { return &_stats_lock; }
4427
4428 public:
4429 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4430 : AbstractGangTask("G1 collection"),
4431 _g1h(g1h),
4432 _queues(task_queues),
4433 _terminator(0, _queues),
4434 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4435 {}
4436
4437 RefToScanQueueSet* queues() { return _queues; }
4438
4439 RefToScanQueue *work_queue(int i) {
4440 return queues()->queue(i);
4441 }
4442
4443 ParallelTaskTerminator* terminator() { return &_terminator; }
4444
4445 virtual void set_for_termination(int active_workers) {
4446 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4447 // in the young space (_par_seq_tasks) in the G1 heap
4448 // for SequentialSubTasksDone.
4449 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4450 // both of which need setting by set_n_termination().
4451 _g1h->SharedHeap::set_n_termination(active_workers);
4452 _g1h->set_n_termination(active_workers);
4453 terminator()->reset_for_reuse(active_workers);
4454 _n_workers = active_workers;
4455 }
4456
4457 // Helps out with CLD processing.
4458 //
4459 // During InitialMark we need to:
4460 // 1) Scavenge all CLDs for the young GC.
4461 // 2) Mark all objects directly reachable from strong CLDs.
4462 template <G1Mark do_mark_object>
4463 class G1CLDClosure : public CLDClosure {
4464 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4465 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4466 G1KlassScanClosure _klass_in_cld_closure;
4467 bool _claim;
4468
4469 public:
4470 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4471 bool only_young, bool claim)
4472 : _oop_closure(oop_closure),
4473 _oop_in_klass_closure(oop_closure->g1(),
4474 oop_closure->pss(),
4475 oop_closure->rp()),
4476 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4477 _claim(claim) {
4478
4479 }
4480
4481 void do_cld(ClassLoaderData* cld) {
4482 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4483 }
4484 };
4485
4486 void work(uint worker_id) {
4487 if (worker_id >= _n_workers) return; // no work needed this round
4488
4489 double start_time_ms = os::elapsedTime() * 1000.0;
4490 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4491
4492 {
4493 ResourceMark rm;
4494 HandleMark hm;
4495
4496 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4497
4498 G1ParScanThreadState pss(_g1h, worker_id, rp);
4499 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4500
4501 pss.set_evac_failure_closure(&evac_failure_cl);
4502
4503 bool only_young = _g1h->g1_policy()->gcs_are_young();
4504
4505 // Non-IM young GC.
4506 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4507 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4508 only_young, // Only process dirty klasses.
4509 false); // No need to claim CLDs.
4510 // IM young GC.
4511 // Strong roots closures.
4512 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4513 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4514 false, // Process all klasses.
4515 true); // Need to claim CLDs.
4516 // Weak roots closures.
4517 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4518 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4519 false, // Process all klasses.
4520 true); // Need to claim CLDs.
4521
4522 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4523 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4524 // IM Weak code roots are handled later.
4525
4526 OopClosure* strong_root_cl;
4527 OopClosure* weak_root_cl;
4528 CLDClosure* strong_cld_cl;
4529 CLDClosure* weak_cld_cl;
4530 CodeBlobClosure* strong_code_cl;
4531
4532 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4533 // We also need to mark copied objects.
4534 strong_root_cl = &scan_mark_root_cl;
4535 strong_cld_cl = &scan_mark_cld_cl;
4536 strong_code_cl = &scan_mark_code_cl;
4537 if (ClassUnloadingWithConcurrentMark) {
4538 weak_root_cl = &scan_mark_weak_root_cl;
4539 weak_cld_cl = &scan_mark_weak_cld_cl;
4540 } else {
4541 weak_root_cl = &scan_mark_root_cl;
4542 weak_cld_cl = &scan_mark_cld_cl;
4543 }
4544 } else {
4545 strong_root_cl = &scan_only_root_cl;
4546 weak_root_cl = &scan_only_root_cl;
4547 strong_cld_cl = &scan_only_cld_cl;
4548 weak_cld_cl = &scan_only_cld_cl;
4549 strong_code_cl = &scan_only_code_cl;
4550 }
4551
4552
4553 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4554
4555 pss.start_strong_roots();
4556 _g1h->g1_process_roots(strong_root_cl,
4557 weak_root_cl,
4558 &push_heap_rs_cl,
4559 strong_cld_cl,
4560 weak_cld_cl,
4561 strong_code_cl,
4562 worker_id);
4563
4564 pss.end_strong_roots();
4565
4566 {
4567 double start = os::elapsedTime();
4568 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4569 evac.do_void();
4570 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4571 double term_ms = pss.term_time()*1000.0;
4572 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4573 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4574 }
4575 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4576 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4577
4578 if (PrintTerminationStats) {
4579 MutexLocker x(stats_lock());
4580 pss.print_termination_stats(worker_id);
4581 }
4582
4583 assert(pss.queue_is_empty(), "should be empty");
4584
4585 // Close the inner scope so that the ResourceMark and HandleMark
4586 // destructors are executed here and are included as part of the
4587 // "GC Worker Time".
4588 }
4589
4590 double end_time_ms = os::elapsedTime() * 1000.0;
4591 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4592 }
4593 };
4594
4595 // *** Common G1 Evacuation Stuff
4596
4597 // This method is run in a GC worker.
4598
4599 void
4600 G1CollectedHeap::
4601 g1_process_roots(OopClosure* scan_non_heap_roots,
4602 OopClosure* scan_non_heap_weak_roots,
4603 G1ParPushHeapRSClosure* scan_rs,
4604 CLDClosure* scan_strong_clds,
4605 CLDClosure* scan_weak_clds,
4606 CodeBlobClosure* scan_strong_code,
4607 uint worker_i) {
4608
4609 // First scan the shared roots.
4610 double ext_roots_start = os::elapsedTime();
4611 double closure_app_time_sec = 0.0;
4612
4613 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4614 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4615
4616 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4617 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4618
4619 process_roots(false, // no scoping; this is parallel code
4620 SharedHeap::SO_None,
4621 &buf_scan_non_heap_roots,
4622 &buf_scan_non_heap_weak_roots,
4623 scan_strong_clds,
4624 // Unloading Initial Marks handle the weak CLDs separately.
4625 (trace_metadata ? NULL : scan_weak_clds),
4626 scan_strong_code);
4627
4628 // Now the CM ref_processor roots.
4629 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4630 // We need to treat the discovered reference lists of the
4631 // concurrent mark ref processor as roots and keep entries
4632 // (which are added by the marking threads) on them live
4633 // until they can be processed at the end of marking.
4634 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4635 }
4636
4637 if (trace_metadata) {
4638 // Barrier to make sure all workers passed
4639 // the strong CLD and strong nmethods phases.
4640 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4641
4642 // Now take the complement of the strong CLDs.
4643 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4644 }
4645
4646 // Finish up any enqueued closure apps (attributed as object copy time).
4647 buf_scan_non_heap_roots.done();
4648 buf_scan_non_heap_weak_roots.done();
4649
4650 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4651 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4652
4653 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4654
4655 double ext_root_time_ms =
4656 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4657
4658 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4659
4660 // During conc marking we have to filter the per-thread SATB buffers
4661 // to make sure we remove any oops into the CSet (which will show up
4662 // as implicitly live).
4663 double satb_filtering_ms = 0.0;
4664 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4665 if (mark_in_progress()) {
4666 double satb_filter_start = os::elapsedTime();
4667
4668 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4669
4670 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4671 }
4672 }
4673 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4674
4675 // Now scan the complement of the collection set.
4676 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4677
4678 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4679
4680 _process_strong_tasks->all_tasks_completed();
4681 }
4682
4683 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4684 private:
4685 BoolObjectClosure* _is_alive;
4686 int _initial_string_table_size;
4687 int _initial_symbol_table_size;
4688
4689 bool _process_strings;
4690 int _strings_processed;
4691 int _strings_removed;
4692
4693 bool _process_symbols;
4694 int _symbols_processed;
4695 int _symbols_removed;
4696
4697 public:
4698 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4699 AbstractGangTask("String/Symbol Unlinking"),
4700 _is_alive(is_alive),
4701 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4702 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4703
4704 _initial_string_table_size = StringTable::the_table()->table_size();
4705 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4706 if (process_strings) {
4707 StringTable::clear_parallel_claimed_index();
4708 }
4709 if (process_symbols) {
4710 SymbolTable::clear_parallel_claimed_index();
4711 }
4712 }
4713
4714 ~G1StringSymbolTableUnlinkTask() {
4715 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4716 err_msg("claim value %d after unlink less than initial string table size %d",
4717 StringTable::parallel_claimed_index(), _initial_string_table_size));
4718 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4719 err_msg("claim value %d after unlink less than initial symbol table size %d",
4720 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4721
4722 if (G1TraceStringSymbolTableScrubbing) {
4723 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4724 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4725 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4726 strings_processed(), strings_removed(),
4727 symbols_processed(), symbols_removed());
4728 }
4729 }
4730
4731 void work(uint worker_id) {
4732 int strings_processed = 0;
4733 int strings_removed = 0;
4734 int symbols_processed = 0;
4735 int symbols_removed = 0;
4736 if (_process_strings) {
4737 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4738 Atomic::add(strings_processed, &_strings_processed);
4739 Atomic::add(strings_removed, &_strings_removed);
4740 }
4741 if (_process_symbols) {
4742 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4743 Atomic::add(symbols_processed, &_symbols_processed);
4744 Atomic::add(symbols_removed, &_symbols_removed);
4745 }
4746 }
4747
4748 size_t strings_processed() const { return (size_t)_strings_processed; }
4749 size_t strings_removed() const { return (size_t)_strings_removed; }
4750
4751 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4752 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4753 };
4754
4755 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4756 private:
4757 static Monitor* _lock;
4758
4759 BoolObjectClosure* const _is_alive;
4760 const bool _unloading_occurred;
4761 const uint _num_workers;
4762
4763 // Variables used to claim nmethods.
4764 nmethod* _first_nmethod;
4765 volatile nmethod* _claimed_nmethod;
4766
4767 // The list of nmethods that need to be processed by the second pass.
4768 volatile nmethod* _postponed_list;
4769 volatile uint _num_entered_barrier;
4770
4771 public:
4772 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4773 _is_alive(is_alive),
4774 _unloading_occurred(unloading_occurred),
4775 _num_workers(num_workers),
4776 _first_nmethod(NULL),
4777 _claimed_nmethod(NULL),
4778 _postponed_list(NULL),
4779 _num_entered_barrier(0)
4780 {
4781 nmethod::increase_unloading_clock();
4782 // Get first alive nmethod
4783 NMethodIterator iter = NMethodIterator();
4784 if(iter.next_alive()) {
4785 _first_nmethod = iter.method();
4786 }
4787 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4788 }
4789
4790 ~G1CodeCacheUnloadingTask() {
4791 CodeCache::verify_clean_inline_caches();
4792
4793 CodeCache::set_needs_cache_clean(false);
4794 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4795
4796 CodeCache::verify_icholder_relocations();
4797 }
4798
4799 private:
4800 void add_to_postponed_list(nmethod* nm) {
4801 nmethod* old;
4802 do {
4803 old = (nmethod*)_postponed_list;
4804 nm->set_unloading_next(old);
4805 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4806 }
4807
4808 void clean_nmethod(nmethod* nm) {
4809 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4810
4811 if (postponed) {
4812 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4813 add_to_postponed_list(nm);
4814 }
4815
4816 // Mark that this thread has been cleaned/unloaded.
4817 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4818 nm->set_unloading_clock(nmethod::global_unloading_clock());
4819 }
4820
4821 void clean_nmethod_postponed(nmethod* nm) {
4822 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4823 }
4824
4825 static const int MaxClaimNmethods = 16;
4826
4827 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4828 nmethod* first;
4829 NMethodIterator last;
4830
4831 do {
4832 *num_claimed_nmethods = 0;
4833
4834 first = (nmethod*)_claimed_nmethod;
4835 last = NMethodIterator(first);
4836
4837 if (first != NULL) {
4838
4839 for (int i = 0; i < MaxClaimNmethods; i++) {
4840 if (!last.next_alive()) {
4841 break;
4842 }
4843 claimed_nmethods[i] = last.method();
4844 (*num_claimed_nmethods)++;
4845 }
4846 }
4847
4848 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4849 }
4850
4851 nmethod* claim_postponed_nmethod() {
4852 nmethod* claim;
4853 nmethod* next;
4854
4855 do {
4856 claim = (nmethod*)_postponed_list;
4857 if (claim == NULL) {
4858 return NULL;
4859 }
4860
4861 next = claim->unloading_next();
4862
4863 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4864
4865 return claim;
4866 }
4867
4868 public:
4869 // Mark that we're done with the first pass of nmethod cleaning.
4870 void barrier_mark(uint worker_id) {
4871 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4872 _num_entered_barrier++;
4873 if (_num_entered_barrier == _num_workers) {
4874 ml.notify_all();
4875 }
4876 }
4877
4878 // See if we have to wait for the other workers to
4879 // finish their first-pass nmethod cleaning work.
4880 void barrier_wait(uint worker_id) {
4881 if (_num_entered_barrier < _num_workers) {
4882 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4883 while (_num_entered_barrier < _num_workers) {
4884 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4885 }
4886 }
4887 }
4888
4889 // Cleaning and unloading of nmethods. Some work has to be postponed
4890 // to the second pass, when we know which nmethods survive.
4891 void work_first_pass(uint worker_id) {
4892 // The first nmethods is claimed by the first worker.
4893 if (worker_id == 0 && _first_nmethod != NULL) {
4894 clean_nmethod(_first_nmethod);
4895 _first_nmethod = NULL;
4896 }
4897
4898 int num_claimed_nmethods;
4899 nmethod* claimed_nmethods[MaxClaimNmethods];
4900
4901 while (true) {
4902 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4903
4904 if (num_claimed_nmethods == 0) {
4905 break;
4906 }
4907
4908 for (int i = 0; i < num_claimed_nmethods; i++) {
4909 clean_nmethod(claimed_nmethods[i]);
4910 }
4911 }
4912
4913 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4914 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4915 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4916 }
4917
4918 void work_second_pass(uint worker_id) {
4919 nmethod* nm;
4920 // Take care of postponed nmethods.
4921 while ((nm = claim_postponed_nmethod()) != NULL) {
4922 clean_nmethod_postponed(nm);
4923 }
4924 }
4925 };
4926
4927 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4928
4929 class G1KlassCleaningTask : public StackObj {
4930 BoolObjectClosure* _is_alive;
4931 volatile jint _clean_klass_tree_claimed;
4932 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4933
4934 public:
4935 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4936 _is_alive(is_alive),
4937 _clean_klass_tree_claimed(0),
4938 _klass_iterator() {
4939 }
4940
4941 private:
4942 bool claim_clean_klass_tree_task() {
4943 if (_clean_klass_tree_claimed) {
4944 return false;
4945 }
4946
4947 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4948 }
4949
4950 InstanceKlass* claim_next_klass() {
4951 Klass* klass;
4952 do {
4953 klass =_klass_iterator.next_klass();
4954 } while (klass != NULL && !klass->oop_is_instance());
4955
4956 return (InstanceKlass*)klass;
4957 }
4958
4959 public:
4960
4961 void clean_klass(InstanceKlass* ik) {
4962 ik->clean_implementors_list(_is_alive);
4963 ik->clean_method_data(_is_alive);
4964
4965 // G1 specific cleanup work that has
4966 // been moved here to be done in parallel.
4967 ik->clean_dependent_nmethods();
4968 if (JvmtiExport::has_redefined_a_class()) {
4969 InstanceKlass::purge_previous_versions(ik);
4970 }
4971 }
4972
4973 void work() {
4974 ResourceMark rm;
4975
4976 // One worker will clean the subklass/sibling klass tree.
4977 if (claim_clean_klass_tree_task()) {
4978 Klass::clean_subklass_tree(_is_alive);
4979 }
4980
4981 // All workers will help cleaning the classes,
4982 InstanceKlass* klass;
4983 while ((klass = claim_next_klass()) != NULL) {
4984 clean_klass(klass);
4985 }
4986 }
4987 };
4988
4989 // To minimize the remark pause times, the tasks below are done in parallel.
4990 class G1ParallelCleaningTask : public AbstractGangTask {
4991 private:
4992 G1StringSymbolTableUnlinkTask _string_symbol_task;
4993 G1CodeCacheUnloadingTask _code_cache_task;
4994 G1KlassCleaningTask _klass_cleaning_task;
4995
4996 public:
4997 // The constructor is run in the VMThread.
4998 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4999 AbstractGangTask("Parallel Cleaning"),
5000 _string_symbol_task(is_alive, process_strings, process_symbols),
5001 _code_cache_task(num_workers, is_alive, unloading_occurred),
5002 _klass_cleaning_task(is_alive) {
5003 }
5004
5005 void pre_work_verification() {
5006 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5007 }
5008
5009 void post_work_verification() {
5010 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5011 }
5012
5013 // The parallel work done by all worker threads.
5014 void work(uint worker_id) {
5015 pre_work_verification();
5016
5017 // Do first pass of code cache cleaning.
5018 _code_cache_task.work_first_pass(worker_id);
5019
5020 // Let the threads mark that the first pass is done.
5021 _code_cache_task.barrier_mark(worker_id);
5022
5023 // Clean the Strings and Symbols.
5024 _string_symbol_task.work(worker_id);
5025
5026 // Wait for all workers to finish the first code cache cleaning pass.
5027 _code_cache_task.barrier_wait(worker_id);
5028
5029 // Do the second code cache cleaning work, which realize on
5030 // the liveness information gathered during the first pass.
5031 _code_cache_task.work_second_pass(worker_id);
5032
5033 // Clean all klasses that were not unloaded.
5034 _klass_cleaning_task.work();
5035
5036 post_work_verification();
5037 }
5038 };
5039
5040
5041 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5042 bool process_strings,
5043 bool process_symbols,
5044 bool class_unloading_occurred) {
5045 uint n_workers = workers()->active_workers();
5046
5047 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5048 n_workers, class_unloading_occurred);
5049 set_par_threads(n_workers);
5050 workers()->run_task(&g1_unlink_task);
5051 set_par_threads(0);
5052 }
5053
5054 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5055 bool process_strings, bool process_symbols) {
5056 {
5057 uint n_workers = _g1h->workers()->active_workers();
5058 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5059 set_par_threads(n_workers);
5060 workers()->run_task(&g1_unlink_task);
5061 set_par_threads(0);
5062 }
5063
5064 if (G1StringDedup::is_enabled()) {
5065 G1StringDedup::unlink(is_alive);
5066 }
5067 }
5068
5069 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5070 private:
5071 DirtyCardQueueSet* _queue;
5072 public:
5073 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5074
5075 virtual void work(uint worker_id) {
5076 double start_time = os::elapsedTime();
5077
5078 RedirtyLoggedCardTableEntryClosure cl;
5079 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5080
5081 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5082 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5083 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5084 }
5085 };
5086
5087 void G1CollectedHeap::redirty_logged_cards() {
5088 double redirty_logged_cards_start = os::elapsedTime();
5089
5090 uint n_workers = _g1h->workers()->active_workers();
5091
5092 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5093 dirty_card_queue_set().reset_for_par_iteration();
5094 set_par_threads(n_workers);
5095 workers()->run_task(&redirty_task);
5096 set_par_threads(0);
5097
5098 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5099 dcq.merge_bufferlists(&dirty_card_queue_set());
5100 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5101
5102 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5103 }
5104
5105 // Weak Reference Processing support
5106
5107 // An always "is_alive" closure that is used to preserve referents.
5108 // If the object is non-null then it's alive. Used in the preservation
5109 // of referent objects that are pointed to by reference objects
5110 // discovered by the CM ref processor.
5111 class G1AlwaysAliveClosure: public BoolObjectClosure {
5112 G1CollectedHeap* _g1;
5113 public:
5114 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5115 bool do_object_b(oop p) {
5116 if (p != NULL) {
5117 return true;
5118 }
5119 return false;
5120 }
5121 };
5122
5123 bool G1STWIsAliveClosure::do_object_b(oop p) {
5124 // An object is reachable if it is outside the collection set,
5125 // or is inside and copied.
5126 return !_g1->obj_in_cs(p) || p->is_forwarded();
5127 }
5128
5129 // Non Copying Keep Alive closure
5130 class G1KeepAliveClosure: public OopClosure {
5131 G1CollectedHeap* _g1;
5132 public:
5133 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5134 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5135 void do_oop(oop* p) {
5136 oop obj = *p;
5137 assert(obj != NULL, "the caller should have filtered out NULL values");
5138
5139 const InCSetState cset_state = _g1->in_cset_state(obj);
5140 if (!cset_state.is_in_cset_or_humongous()) {
5141 return;
5142 }
5143 if (cset_state.is_in_cset()) {
5144 assert( obj->is_forwarded(), "invariant" );
5145 *p = obj->forwardee();
5146 } else {
5147 assert(!obj->is_forwarded(), "invariant" );
5148 assert(cset_state.is_humongous(),
5149 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5150 _g1->set_humongous_is_live(obj);
5151 }
5152 }
5153 };
5154
5155 // Copying Keep Alive closure - can be called from both
5156 // serial and parallel code as long as different worker
5157 // threads utilize different G1ParScanThreadState instances
5158 // and different queues.
5159
5160 class G1CopyingKeepAliveClosure: public OopClosure {
5161 G1CollectedHeap* _g1h;
5162 OopClosure* _copy_non_heap_obj_cl;
5163 G1ParScanThreadState* _par_scan_state;
5164
5165 public:
5166 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5167 OopClosure* non_heap_obj_cl,
5168 G1ParScanThreadState* pss):
5169 _g1h(g1h),
5170 _copy_non_heap_obj_cl(non_heap_obj_cl),
5171 _par_scan_state(pss)
5172 {}
5173
5174 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5175 virtual void do_oop( oop* p) { do_oop_work(p); }
5176
5177 template <class T> void do_oop_work(T* p) {
5178 oop obj = oopDesc::load_decode_heap_oop(p);
5179
5180 if (_g1h->is_in_cset_or_humongous(obj)) {
5181 // If the referent object has been forwarded (either copied
5182 // to a new location or to itself in the event of an
5183 // evacuation failure) then we need to update the reference
5184 // field and, if both reference and referent are in the G1
5185 // heap, update the RSet for the referent.
5186 //
5187 // If the referent has not been forwarded then we have to keep
5188 // it alive by policy. Therefore we have copy the referent.
5189 //
5190 // If the reference field is in the G1 heap then we can push
5191 // on the PSS queue. When the queue is drained (after each
5192 // phase of reference processing) the object and it's followers
5193 // will be copied, the reference field set to point to the
5194 // new location, and the RSet updated. Otherwise we need to
5195 // use the the non-heap or metadata closures directly to copy
5196 // the referent object and update the pointer, while avoiding
5197 // updating the RSet.
5198
5199 if (_g1h->is_in_g1_reserved(p)) {
5200 _par_scan_state->push_on_queue(p);
5201 } else {
5202 assert(!Metaspace::contains((const void*)p),
5203 err_msg("Unexpectedly found a pointer from metadata: "
5204 PTR_FORMAT, p));
5205 _copy_non_heap_obj_cl->do_oop(p);
5206 }
5207 }
5208 }
5209 };
5210
5211 // Serial drain queue closure. Called as the 'complete_gc'
5212 // closure for each discovered list in some of the
5213 // reference processing phases.
5214
5215 class G1STWDrainQueueClosure: public VoidClosure {
5216 protected:
5217 G1CollectedHeap* _g1h;
5218 G1ParScanThreadState* _par_scan_state;
5219
5220 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5221
5222 public:
5223 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5224 _g1h(g1h),
5225 _par_scan_state(pss)
5226 { }
5227
5228 void do_void() {
5229 G1ParScanThreadState* const pss = par_scan_state();
5230 pss->trim_queue();
5231 }
5232 };
5233
5234 // Parallel Reference Processing closures
5235
5236 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5237 // processing during G1 evacuation pauses.
5238
5239 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5240 private:
5241 G1CollectedHeap* _g1h;
5242 RefToScanQueueSet* _queues;
5243 FlexibleWorkGang* _workers;
5244 int _active_workers;
5245
5246 public:
5247 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5248 FlexibleWorkGang* workers,
5249 RefToScanQueueSet *task_queues,
5250 int n_workers) :
5251 _g1h(g1h),
5252 _queues(task_queues),
5253 _workers(workers),
5254 _active_workers(n_workers)
5255 {
5256 assert(n_workers > 0, "shouldn't call this otherwise");
5257 }
5258
5259 // Executes the given task using concurrent marking worker threads.
5260 virtual void execute(ProcessTask& task);
5261 virtual void execute(EnqueueTask& task);
5262 };
5263
5264 // Gang task for possibly parallel reference processing
5265
5266 class G1STWRefProcTaskProxy: public AbstractGangTask {
5267 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5268 ProcessTask& _proc_task;
5269 G1CollectedHeap* _g1h;
5270 RefToScanQueueSet *_task_queues;
5271 ParallelTaskTerminator* _terminator;
5272
5273 public:
5274 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5275 G1CollectedHeap* g1h,
5276 RefToScanQueueSet *task_queues,
5277 ParallelTaskTerminator* terminator) :
5278 AbstractGangTask("Process reference objects in parallel"),
5279 _proc_task(proc_task),
5280 _g1h(g1h),
5281 _task_queues(task_queues),
5282 _terminator(terminator)
5283 {}
5284
5285 virtual void work(uint worker_id) {
5286 // The reference processing task executed by a single worker.
5287 ResourceMark rm;
5288 HandleMark hm;
5289
5290 G1STWIsAliveClosure is_alive(_g1h);
5291
5292 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5293 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5294
5295 pss.set_evac_failure_closure(&evac_failure_cl);
5296
5297 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5298
5299 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5300
5301 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5302
5303 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5304 // We also need to mark copied objects.
5305 copy_non_heap_cl = ©_mark_non_heap_cl;
5306 }
5307
5308 // Keep alive closure.
5309 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5310
5311 // Complete GC closure
5312 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5313
5314 // Call the reference processing task's work routine.
5315 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5316
5317 // Note we cannot assert that the refs array is empty here as not all
5318 // of the processing tasks (specifically phase2 - pp2_work) execute
5319 // the complete_gc closure (which ordinarily would drain the queue) so
5320 // the queue may not be empty.
5321 }
5322 };
5323
5324 // Driver routine for parallel reference processing.
5325 // Creates an instance of the ref processing gang
5326 // task and has the worker threads execute it.
5327 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5328 assert(_workers != NULL, "Need parallel worker threads.");
5329
5330 ParallelTaskTerminator terminator(_active_workers, _queues);
5331 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5332
5333 _g1h->set_par_threads(_active_workers);
5334 _workers->run_task(&proc_task_proxy);
5335 _g1h->set_par_threads(0);
5336 }
5337
5338 // Gang task for parallel reference enqueueing.
5339
5340 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5341 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5342 EnqueueTask& _enq_task;
5343
5344 public:
5345 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5346 AbstractGangTask("Enqueue reference objects in parallel"),
5347 _enq_task(enq_task)
5348 { }
5349
5350 virtual void work(uint worker_id) {
5351 _enq_task.work(worker_id);
5352 }
5353 };
5354
5355 // Driver routine for parallel reference enqueueing.
5356 // Creates an instance of the ref enqueueing gang
5357 // task and has the worker threads execute it.
5358
5359 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5360 assert(_workers != NULL, "Need parallel worker threads.");
5361
5362 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5363
5364 _g1h->set_par_threads(_active_workers);
5365 _workers->run_task(&enq_task_proxy);
5366 _g1h->set_par_threads(0);
5367 }
5368
5369 // End of weak reference support closures
5370
5371 // Abstract task used to preserve (i.e. copy) any referent objects
5372 // that are in the collection set and are pointed to by reference
5373 // objects discovered by the CM ref processor.
5374
5375 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5376 protected:
5377 G1CollectedHeap* _g1h;
5378 RefToScanQueueSet *_queues;
5379 ParallelTaskTerminator _terminator;
5380 uint _n_workers;
5381
5382 public:
5383 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5384 AbstractGangTask("ParPreserveCMReferents"),
5385 _g1h(g1h),
5386 _queues(task_queues),
5387 _terminator(workers, _queues),
5388 _n_workers(workers)
5389 { }
5390
5391 void work(uint worker_id) {
5392 ResourceMark rm;
5393 HandleMark hm;
5394
5395 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5396 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5397
5398 pss.set_evac_failure_closure(&evac_failure_cl);
5399
5400 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5401
5402 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5403
5404 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5405
5406 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5407
5408 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5409 // We also need to mark copied objects.
5410 copy_non_heap_cl = ©_mark_non_heap_cl;
5411 }
5412
5413 // Is alive closure
5414 G1AlwaysAliveClosure always_alive(_g1h);
5415
5416 // Copying keep alive closure. Applied to referent objects that need
5417 // to be copied.
5418 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5419
5420 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5421
5422 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5423 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5424
5425 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5426 // So this must be true - but assert just in case someone decides to
5427 // change the worker ids.
5428 assert(0 <= worker_id && worker_id < limit, "sanity");
5429 assert(!rp->discovery_is_atomic(), "check this code");
5430
5431 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5432 for (uint idx = worker_id; idx < limit; idx += stride) {
5433 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5434
5435 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5436 while (iter.has_next()) {
5437 // Since discovery is not atomic for the CM ref processor, we
5438 // can see some null referent objects.
5439 iter.load_ptrs(DEBUG_ONLY(true));
5440 oop ref = iter.obj();
5441
5442 // This will filter nulls.
5443 if (iter.is_referent_alive()) {
5444 iter.make_referent_alive();
5445 }
5446 iter.move_to_next();
5447 }
5448 }
5449
5450 // Drain the queue - which may cause stealing
5451 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5452 drain_queue.do_void();
5453 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5454 assert(pss.queue_is_empty(), "should be");
5455 }
5456 };
5457
5458 // Weak Reference processing during an evacuation pause (part 1).
5459 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5460 double ref_proc_start = os::elapsedTime();
5461
5462 ReferenceProcessor* rp = _ref_processor_stw;
5463 assert(rp->discovery_enabled(), "should have been enabled");
5464
5465 // Any reference objects, in the collection set, that were 'discovered'
5466 // by the CM ref processor should have already been copied (either by
5467 // applying the external root copy closure to the discovered lists, or
5468 // by following an RSet entry).
5469 //
5470 // But some of the referents, that are in the collection set, that these
5471 // reference objects point to may not have been copied: the STW ref
5472 // processor would have seen that the reference object had already
5473 // been 'discovered' and would have skipped discovering the reference,
5474 // but would not have treated the reference object as a regular oop.
5475 // As a result the copy closure would not have been applied to the
5476 // referent object.
5477 //
5478 // We need to explicitly copy these referent objects - the references
5479 // will be processed at the end of remarking.
5480 //
5481 // We also need to do this copying before we process the reference
5482 // objects discovered by the STW ref processor in case one of these
5483 // referents points to another object which is also referenced by an
5484 // object discovered by the STW ref processor.
5485
5486 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5487
5488 set_par_threads(no_of_gc_workers);
5489 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5490 no_of_gc_workers,
5491 _task_queues);
5492
5493 workers()->run_task(&keep_cm_referents);
5494
5495 set_par_threads(0);
5496
5497 // Closure to test whether a referent is alive.
5498 G1STWIsAliveClosure is_alive(this);
5499
5500 // Even when parallel reference processing is enabled, the processing
5501 // of JNI refs is serial and performed serially by the current thread
5502 // rather than by a worker. The following PSS will be used for processing
5503 // JNI refs.
5504
5505 // Use only a single queue for this PSS.
5506 G1ParScanThreadState pss(this, 0, NULL);
5507
5508 // We do not embed a reference processor in the copying/scanning
5509 // closures while we're actually processing the discovered
5510 // reference objects.
5511 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5512
5513 pss.set_evac_failure_closure(&evac_failure_cl);
5514
5515 assert(pss.queue_is_empty(), "pre-condition");
5516
5517 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5518
5519 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5520
5521 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5522
5523 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5524 // We also need to mark copied objects.
5525 copy_non_heap_cl = ©_mark_non_heap_cl;
5526 }
5527
5528 // Keep alive closure.
5529 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5530
5531 // Serial Complete GC closure
5532 G1STWDrainQueueClosure drain_queue(this, &pss);
5533
5534 // Setup the soft refs policy...
5535 rp->setup_policy(false);
5536
5537 ReferenceProcessorStats stats;
5538 if (!rp->processing_is_mt()) {
5539 // Serial reference processing...
5540 stats = rp->process_discovered_references(&is_alive,
5541 &keep_alive,
5542 &drain_queue,
5543 NULL,
5544 _gc_timer_stw,
5545 _gc_tracer_stw->gc_id());
5546 } else {
5547 // Parallel reference processing
5548 assert(rp->num_q() == no_of_gc_workers, "sanity");
5549 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5550
5551 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5552 stats = rp->process_discovered_references(&is_alive,
5553 &keep_alive,
5554 &drain_queue,
5555 &par_task_executor,
5556 _gc_timer_stw,
5557 _gc_tracer_stw->gc_id());
5558 }
5559
5560 _gc_tracer_stw->report_gc_reference_stats(stats);
5561
5562 // We have completed copying any necessary live referent objects.
5563 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5564
5565 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5566 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5567 }
5568
5569 // Weak Reference processing during an evacuation pause (part 2).
5570 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5571 double ref_enq_start = os::elapsedTime();
5572
5573 ReferenceProcessor* rp = _ref_processor_stw;
5574 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5575
5576 // Now enqueue any remaining on the discovered lists on to
5577 // the pending list.
5578 if (!rp->processing_is_mt()) {
5579 // Serial reference processing...
5580 rp->enqueue_discovered_references();
5581 } else {
5582 // Parallel reference enqueueing
5583
5584 assert(no_of_gc_workers == workers()->active_workers(),
5585 "Need to reset active workers");
5586 assert(rp->num_q() == no_of_gc_workers, "sanity");
5587 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5588
5589 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5590 rp->enqueue_discovered_references(&par_task_executor);
5591 }
5592
5593 rp->verify_no_references_recorded();
5594 assert(!rp->discovery_enabled(), "should have been disabled");
5595
5596 // FIXME
5597 // CM's reference processing also cleans up the string and symbol tables.
5598 // Should we do that here also? We could, but it is a serial operation
5599 // and could significantly increase the pause time.
5600
5601 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5602 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5603 }
5604
5605 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5606 _expand_heap_after_alloc_failure = true;
5607 _evacuation_failed = false;
5608
5609 // Should G1EvacuationFailureALot be in effect for this GC?
5610 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5611
5612 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5613
5614 // Disable the hot card cache.
5615 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5616 hot_card_cache->reset_hot_cache_claimed_index();
5617 hot_card_cache->set_use_cache(false);
5618
5619 uint n_workers;
5620 n_workers =
5621 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5622 workers()->active_workers(),
5623 Threads::number_of_non_daemon_threads());
5624 assert(UseDynamicNumberOfGCThreads ||
5625 n_workers == workers()->total_workers(),
5626 "If not dynamic should be using all the workers");
5627 workers()->set_active_workers(n_workers);
5628 set_par_threads(n_workers);
5629
5630 G1ParTask g1_par_task(this, _task_queues);
5631
5632 init_for_evac_failure(NULL);
5633
5634 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5635 double start_par_time_sec = os::elapsedTime();
5636 double end_par_time_sec;
5637
5638 {
5639 StrongRootsScope srs(this);
5640 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5641 if (g1_policy()->during_initial_mark_pause()) {
5642 ClassLoaderDataGraph::clear_claimed_marks();
5643 }
5644
5645 // The individual threads will set their evac-failure closures.
5646 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5647 // These tasks use ShareHeap::_process_strong_tasks
5648 assert(UseDynamicNumberOfGCThreads ||
5649 workers()->active_workers() == workers()->total_workers(),
5650 "If not dynamic should be using all the workers");
5651 workers()->run_task(&g1_par_task);
5652 end_par_time_sec = os::elapsedTime();
5653
5654 // Closing the inner scope will execute the destructor
5655 // for the StrongRootsScope object. We record the current
5656 // elapsed time before closing the scope so that time
5657 // taken for the SRS destructor is NOT included in the
5658 // reported parallel time.
5659 }
5660
5661 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5662 g1_policy()->phase_times()->record_par_time(par_time_ms);
5663
5664 double code_root_fixup_time_ms =
5665 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5666 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5667
5668 set_par_threads(0);
5669
5670 // Process any discovered reference objects - we have
5671 // to do this _before_ we retire the GC alloc regions
5672 // as we may have to copy some 'reachable' referent
5673 // objects (and their reachable sub-graphs) that were
5674 // not copied during the pause.
5675 process_discovered_references(n_workers);
5676
5677 if (G1StringDedup::is_enabled()) {
5678 G1STWIsAliveClosure is_alive(this);
5679 G1KeepAliveClosure keep_alive(this);
5680 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5681 }
5682
5683 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5684 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5685
5686 // Reset and re-enable the hot card cache.
5687 // Note the counts for the cards in the regions in the
5688 // collection set are reset when the collection set is freed.
5689 hot_card_cache->reset_hot_cache();
5690 hot_card_cache->set_use_cache(true);
5691
5692 purge_code_root_memory();
5693
5694 finalize_for_evac_failure();
5695
5696 if (evacuation_failed()) {
5697 remove_self_forwarding_pointers();
5698
5699 // Reset the G1EvacuationFailureALot counters and flags
5700 // Note: the values are reset only when an actual
5701 // evacuation failure occurs.
5702 NOT_PRODUCT(reset_evacuation_should_fail();)
5703 }
5704
5705 // Enqueue any remaining references remaining on the STW
5706 // reference processor's discovered lists. We need to do
5707 // this after the card table is cleaned (and verified) as
5708 // the act of enqueueing entries on to the pending list
5709 // will log these updates (and dirty their associated
5710 // cards). We need these updates logged to update any
5711 // RSets.
5712 enqueue_discovered_references(n_workers);
5713
5714 redirty_logged_cards();
5715 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5716 }
5717
5718 void G1CollectedHeap::free_region(HeapRegion* hr,
5719 FreeRegionList* free_list,
5720 bool par,
5721 bool locked) {
5722 assert(!hr->is_free(), "the region should not be free");
5723 assert(!hr->is_empty(), "the region should not be empty");
5724 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5725 assert(free_list != NULL, "pre-condition");
5726
5727 if (G1VerifyBitmaps) {
5728 MemRegion mr(hr->bottom(), hr->end());
5729 concurrent_mark()->clearRangePrevBitmap(mr);
5730 }
5731
5732 // Clear the card counts for this region.
5733 // Note: we only need to do this if the region is not young
5734 // (since we don't refine cards in young regions).
5735 if (!hr->is_young()) {
5736 _cg1r->hot_card_cache()->reset_card_counts(hr);
5737 }
5738 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5739 free_list->add_ordered(hr);
5740 }
5741
5742 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5743 FreeRegionList* free_list,
5744 bool par) {
5745 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5746 assert(free_list != NULL, "pre-condition");
5747
5748 size_t hr_capacity = hr->capacity();
5749 // We need to read this before we make the region non-humongous,
5750 // otherwise the information will be gone.
5751 uint last_index = hr->last_hc_index();
5752 hr->clear_humongous();
5753 free_region(hr, free_list, par);
5754
5755 uint i = hr->hrm_index() + 1;
5756 while (i < last_index) {
5757 HeapRegion* curr_hr = region_at(i);
5758 assert(curr_hr->is_continues_humongous(), "invariant");
5759 curr_hr->clear_humongous();
5760 free_region(curr_hr, free_list, par);
5761 i += 1;
5762 }
5763 }
5764
5765 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5766 const HeapRegionSetCount& humongous_regions_removed) {
5767 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5768 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5769 _old_set.bulk_remove(old_regions_removed);
5770 _humongous_set.bulk_remove(humongous_regions_removed);
5771 }
5772
5773 }
5774
5775 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5776 assert(list != NULL, "list can't be null");
5777 if (!list->is_empty()) {
5778 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5779 _hrm.insert_list_into_free_list(list);
5780 }
5781 }
5782
5783 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5784 _allocator->decrease_used(bytes);
5785 }
5786
5787 class G1ParCleanupCTTask : public AbstractGangTask {
5788 G1SATBCardTableModRefBS* _ct_bs;
5789 G1CollectedHeap* _g1h;
5790 HeapRegion* volatile _su_head;
5791 public:
5792 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5793 G1CollectedHeap* g1h) :
5794 AbstractGangTask("G1 Par Cleanup CT Task"),
5795 _ct_bs(ct_bs), _g1h(g1h) { }
5796
5797 void work(uint worker_id) {
5798 HeapRegion* r;
5799 while (r = _g1h->pop_dirty_cards_region()) {
5800 clear_cards(r);
5801 }
5802 }
5803
5804 void clear_cards(HeapRegion* r) {
5805 // Cards of the survivors should have already been dirtied.
5806 if (!r->is_survivor()) {
5807 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5808 }
5809 }
5810 };
5811
5812 #ifndef PRODUCT
5813 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5814 G1CollectedHeap* _g1h;
5815 G1SATBCardTableModRefBS* _ct_bs;
5816 public:
5817 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5818 : _g1h(g1h), _ct_bs(ct_bs) { }
5819 virtual bool doHeapRegion(HeapRegion* r) {
5820 if (r->is_survivor()) {
5821 _g1h->verify_dirty_region(r);
5822 } else {
5823 _g1h->verify_not_dirty_region(r);
5824 }
5825 return false;
5826 }
5827 };
5828
5829 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5830 // All of the region should be clean.
5831 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5832 MemRegion mr(hr->bottom(), hr->end());
5833 ct_bs->verify_not_dirty_region(mr);
5834 }
5835
5836 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5837 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5838 // dirty allocated blocks as they allocate them. The thread that
5839 // retires each region and replaces it with a new one will do a
5840 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5841 // not dirty that area (one less thing to have to do while holding
5842 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5843 // is dirty.
5844 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5845 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5846 if (hr->is_young()) {
5847 ct_bs->verify_g1_young_region(mr);
5848 } else {
5849 ct_bs->verify_dirty_region(mr);
5850 }
5851 }
5852
5853 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5854 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5855 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5856 verify_dirty_region(hr);
5857 }
5858 }
5859
5860 void G1CollectedHeap::verify_dirty_young_regions() {
5861 verify_dirty_young_list(_young_list->first_region());
5862 }
5863
5864 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5865 HeapWord* tams, HeapWord* end) {
5866 guarantee(tams <= end,
5867 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5868 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5869 if (result < end) {
5870 gclog_or_tty->cr();
5871 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5872 bitmap_name, result);
5873 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5874 bitmap_name, tams, end);
5875 return false;
5876 }
5877 return true;
5878 }
5879
5880 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5881 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5882 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5883
5884 HeapWord* bottom = hr->bottom();
5885 HeapWord* ptams = hr->prev_top_at_mark_start();
5886 HeapWord* ntams = hr->next_top_at_mark_start();
5887 HeapWord* end = hr->end();
5888
5889 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5890
5891 bool res_n = true;
5892 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5893 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5894 // if we happen to be in that state.
5895 if (mark_in_progress() || !_cmThread->in_progress()) {
5896 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5897 }
5898 if (!res_p || !res_n) {
5899 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5900 HR_FORMAT_PARAMS(hr));
5901 gclog_or_tty->print_cr("#### Caller: %s", caller);
5902 return false;
5903 }
5904 return true;
5905 }
5906
5907 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5908 if (!G1VerifyBitmaps) return;
5909
5910 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5911 }
5912
5913 class G1VerifyBitmapClosure : public HeapRegionClosure {
5914 private:
5915 const char* _caller;
5916 G1CollectedHeap* _g1h;
5917 bool _failures;
5918
5919 public:
5920 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5921 _caller(caller), _g1h(g1h), _failures(false) { }
5922
5923 bool failures() { return _failures; }
5924
5925 virtual bool doHeapRegion(HeapRegion* hr) {
5926 if (hr->is_continues_humongous()) return false;
5927
5928 bool result = _g1h->verify_bitmaps(_caller, hr);
5929 if (!result) {
5930 _failures = true;
5931 }
5932 return false;
5933 }
5934 };
5935
5936 void G1CollectedHeap::check_bitmaps(const char* caller) {
5937 if (!G1VerifyBitmaps) return;
5938
5939 G1VerifyBitmapClosure cl(caller, this);
5940 heap_region_iterate(&cl);
5941 guarantee(!cl.failures(), "bitmap verification");
5942 }
5943
5944 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5945 private:
5946 bool _failures;
5947 public:
5948 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5949
5950 virtual bool doHeapRegion(HeapRegion* hr) {
5951 uint i = hr->hrm_index();
5952 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5953 if (hr->is_humongous()) {
5954 if (hr->in_collection_set()) {
5955 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5956 _failures = true;
5957 return true;
5958 }
5959 if (cset_state.is_in_cset()) {
5960 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5961 _failures = true;
5962 return true;
5963 }
5964 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5965 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5966 _failures = true;
5967 return true;
5968 }
5969 } else {
5970 if (cset_state.is_humongous()) {
5971 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5972 _failures = true;
5973 return true;
5974 }
5975 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5976 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5977 hr->in_collection_set(), cset_state.value(), i);
5978 _failures = true;
5979 return true;
5980 }
5981 if (cset_state.is_in_cset()) {
5982 if (hr->is_young() != (cset_state.is_young())) {
5983 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5984 hr->is_young(), cset_state.value(), i);
5985 _failures = true;
5986 return true;
5987 }
5988 if (hr->is_old() != (cset_state.is_old())) {
5989 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5990 hr->is_old(), cset_state.value(), i);
5991 _failures = true;
5992 return true;
5993 }
5994 }
5995 }
5996 return false;
5997 }
5998
5999 bool failures() const { return _failures; }
6000 };
6001
6002 bool G1CollectedHeap::check_cset_fast_test() {
6003 G1CheckCSetFastTableClosure cl;
6004 _hrm.iterate(&cl);
6005 return !cl.failures();
6006 }
6007 #endif // PRODUCT
6008
6009 void G1CollectedHeap::cleanUpCardTable() {
6010 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6011 double start = os::elapsedTime();
6012
6013 {
6014 // Iterate over the dirty cards region list.
6015 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6016
6017 set_par_threads();
6018 workers()->run_task(&cleanup_task);
6019 set_par_threads(0);
6020 #ifndef PRODUCT
6021 if (G1VerifyCTCleanup || VerifyAfterGC) {
6022 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6023 heap_region_iterate(&cleanup_verifier);
6024 }
6025 #endif
6026 }
6027
6028 double elapsed = os::elapsedTime() - start;
6029 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6030 }
6031
6032 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6033 size_t pre_used = 0;
6034 FreeRegionList local_free_list("Local List for CSet Freeing");
6035
6036 double young_time_ms = 0.0;
6037 double non_young_time_ms = 0.0;
6038
6039 // Since the collection set is a superset of the the young list,
6040 // all we need to do to clear the young list is clear its
6041 // head and length, and unlink any young regions in the code below
6042 _young_list->clear();
6043
6044 G1CollectorPolicy* policy = g1_policy();
6045
6046 double start_sec = os::elapsedTime();
6047 bool non_young = true;
6048
6049 HeapRegion* cur = cs_head;
6050 int age_bound = -1;
6051 size_t rs_lengths = 0;
6052
6053 while (cur != NULL) {
6054 assert(!is_on_master_free_list(cur), "sanity");
6055 if (non_young) {
6056 if (cur->is_young()) {
6057 double end_sec = os::elapsedTime();
6058 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6059 non_young_time_ms += elapsed_ms;
6060
6061 start_sec = os::elapsedTime();
6062 non_young = false;
6063 }
6064 } else {
6065 if (!cur->is_young()) {
6066 double end_sec = os::elapsedTime();
6067 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6068 young_time_ms += elapsed_ms;
6069
6070 start_sec = os::elapsedTime();
6071 non_young = true;
6072 }
6073 }
6074
6075 rs_lengths += cur->rem_set()->occupied_locked();
6076
6077 HeapRegion* next = cur->next_in_collection_set();
6078 assert(cur->in_collection_set(), "bad CS");
6079 cur->set_next_in_collection_set(NULL);
6080 cur->set_in_collection_set(false);
6081
6082 if (cur->is_young()) {
6083 int index = cur->young_index_in_cset();
6084 assert(index != -1, "invariant");
6085 assert((uint) index < policy->young_cset_region_length(), "invariant");
6086 size_t words_survived = _surviving_young_words[index];
6087 cur->record_surv_words_in_group(words_survived);
6088
6089 // At this point the we have 'popped' cur from the collection set
6090 // (linked via next_in_collection_set()) but it is still in the
6091 // young list (linked via next_young_region()). Clear the
6092 // _next_young_region field.
6093 cur->set_next_young_region(NULL);
6094 } else {
6095 int index = cur->young_index_in_cset();
6096 assert(index == -1, "invariant");
6097 }
6098
6099 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6100 (!cur->is_young() && cur->young_index_in_cset() == -1),
6101 "invariant" );
6102
6103 if (!cur->evacuation_failed()) {
6104 MemRegion used_mr = cur->used_region();
6105
6106 // And the region is empty.
6107 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6108 pre_used += cur->used();
6109 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6110 } else {
6111 cur->uninstall_surv_rate_group();
6112 if (cur->is_young()) {
6113 cur->set_young_index_in_cset(-1);
6114 }
6115 cur->set_evacuation_failed(false);
6116 // The region is now considered to be old.
6117 cur->set_old();
6118 _old_set.add(cur);
6119 evacuation_info.increment_collectionset_used_after(cur->used());
6120 }
6121 cur = next;
6122 }
6123
6124 evacuation_info.set_regions_freed(local_free_list.length());
6125 policy->record_max_rs_lengths(rs_lengths);
6126 policy->cset_regions_freed();
6127
6128 double end_sec = os::elapsedTime();
6129 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6130
6131 if (non_young) {
6132 non_young_time_ms += elapsed_ms;
6133 } else {
6134 young_time_ms += elapsed_ms;
6135 }
6136
6137 prepend_to_freelist(&local_free_list);
6138 decrement_summary_bytes(pre_used);
6139 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6140 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6141 }
6142
6143 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6144 private:
6145 FreeRegionList* _free_region_list;
6146 HeapRegionSet* _proxy_set;
6147 HeapRegionSetCount _humongous_regions_removed;
6148 size_t _freed_bytes;
6149 public:
6150
6151 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6152 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6153 }
6154
6155 virtual bool doHeapRegion(HeapRegion* r) {
6156 if (!r->is_starts_humongous()) {
6157 return false;
6158 }
6159
6160 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6161
6162 oop obj = (oop)r->bottom();
6163 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6164
6165 // The following checks whether the humongous object is live are sufficient.
6166 // The main additional check (in addition to having a reference from the roots
6167 // or the young gen) is whether the humongous object has a remembered set entry.
6168 //
6169 // A humongous object cannot be live if there is no remembered set for it
6170 // because:
6171 // - there can be no references from within humongous starts regions referencing
6172 // the object because we never allocate other objects into them.
6173 // (I.e. there are no intra-region references that may be missed by the
6174 // remembered set)
6175 // - as soon there is a remembered set entry to the humongous starts region
6176 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6177 // until the end of a concurrent mark.
6178 //
6179 // It is not required to check whether the object has been found dead by marking
6180 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6181 // all objects allocated during that time are considered live.
6182 // SATB marking is even more conservative than the remembered set.
6183 // So if at this point in the collection there is no remembered set entry,
6184 // nobody has a reference to it.
6185 // At the start of collection we flush all refinement logs, and remembered sets
6186 // are completely up-to-date wrt to references to the humongous object.
6187 //
6188 // Other implementation considerations:
6189 // - never consider object arrays at this time because they would pose
6190 // considerable effort for cleaning up the the remembered sets. This is
6191 // required because stale remembered sets might reference locations that
6192 // are currently allocated into.
6193 uint region_idx = r->hrm_index();
6194 if (g1h->humongous_is_live(region_idx) ||
6195 g1h->humongous_region_is_always_live(region_idx)) {
6196
6197 if (G1TraceEagerReclaimHumongousObjects) {
6198 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6199 region_idx,
6200 obj->size()*HeapWordSize,
6201 r->bottom(),
6202 r->region_num(),
6203 r->rem_set()->occupied(),
6204 r->rem_set()->strong_code_roots_list_length(),
6205 next_bitmap->isMarked(r->bottom()),
6206 g1h->humongous_is_live(region_idx),
6207 obj->is_objArray()
6208 );
6209 }
6210
6211 return false;
6212 }
6213
6214 guarantee(!obj->is_objArray(),
6215 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6216 r->bottom()));
6217
6218 if (G1TraceEagerReclaimHumongousObjects) {
6219 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6220 region_idx,
6221 obj->size()*HeapWordSize,
6222 r->bottom(),
6223 r->region_num(),
6224 r->rem_set()->occupied(),
6225 r->rem_set()->strong_code_roots_list_length(),
6226 next_bitmap->isMarked(r->bottom()),
6227 g1h->humongous_is_live(region_idx),
6228 obj->is_objArray()
6229 );
6230 }
6231 // Need to clear mark bit of the humongous object if already set.
6232 if (next_bitmap->isMarked(r->bottom())) {
6233 next_bitmap->clear(r->bottom());
6234 }
6235 _freed_bytes += r->used();
6236 r->set_containing_set(NULL);
6237 _humongous_regions_removed.increment(1u, r->capacity());
6238 g1h->free_humongous_region(r, _free_region_list, false);
6239
6240 return false;
6241 }
6242
6243 HeapRegionSetCount& humongous_free_count() {
6244 return _humongous_regions_removed;
6245 }
6246
6247 size_t bytes_freed() const {
6248 return _freed_bytes;
6249 }
6250
6251 size_t humongous_reclaimed() const {
6252 return _humongous_regions_removed.length();
6253 }
6254 };
6255
6256 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6257 assert_at_safepoint(true);
6258
6259 if (!G1EagerReclaimHumongousObjects ||
6260 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6261 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6262 return;
6263 }
6264
6265 double start_time = os::elapsedTime();
6266
6267 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6268
6269 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6270 heap_region_iterate(&cl);
6271
6272 HeapRegionSetCount empty_set;
6273 remove_from_old_sets(empty_set, cl.humongous_free_count());
6274
6275 G1HRPrinter* hr_printer = _g1h->hr_printer();
6276 if (hr_printer->is_active()) {
6277 FreeRegionListIterator iter(&local_cleanup_list);
6278 while (iter.more_available()) {
6279 HeapRegion* hr = iter.get_next();
6280 hr_printer->cleanup(hr);
6281 }
6282 }
6283
6284 prepend_to_freelist(&local_cleanup_list);
6285 decrement_summary_bytes(cl.bytes_freed());
6286
6287 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6288 cl.humongous_reclaimed());
6289 }
6290
6291 // This routine is similar to the above but does not record
6292 // any policy statistics or update free lists; we are abandoning
6293 // the current incremental collection set in preparation of a
6294 // full collection. After the full GC we will start to build up
6295 // the incremental collection set again.
6296 // This is only called when we're doing a full collection
6297 // and is immediately followed by the tearing down of the young list.
6298
6299 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6300 HeapRegion* cur = cs_head;
6301
6302 while (cur != NULL) {
6303 HeapRegion* next = cur->next_in_collection_set();
6304 assert(cur->in_collection_set(), "bad CS");
6305 cur->set_next_in_collection_set(NULL);
6306 cur->set_in_collection_set(false);
6307 cur->set_young_index_in_cset(-1);
6308 cur = next;
6309 }
6310 }
6311
6312 void G1CollectedHeap::set_free_regions_coming() {
6313 if (G1ConcRegionFreeingVerbose) {
6314 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6315 "setting free regions coming");
6316 }
6317
6318 assert(!free_regions_coming(), "pre-condition");
6319 _free_regions_coming = true;
6320 }
6321
6322 void G1CollectedHeap::reset_free_regions_coming() {
6323 assert(free_regions_coming(), "pre-condition");
6324
6325 {
6326 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6327 _free_regions_coming = false;
6328 SecondaryFreeList_lock->notify_all();
6329 }
6330
6331 if (G1ConcRegionFreeingVerbose) {
6332 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6333 "reset free regions coming");
6334 }
6335 }
6336
6337 void G1CollectedHeap::wait_while_free_regions_coming() {
6338 // Most of the time we won't have to wait, so let's do a quick test
6339 // first before we take the lock.
6340 if (!free_regions_coming()) {
6341 return;
6342 }
6343
6344 if (G1ConcRegionFreeingVerbose) {
6345 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6346 "waiting for free regions");
6347 }
6348
6349 {
6350 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6351 while (free_regions_coming()) {
6352 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6353 }
6354 }
6355
6356 if (G1ConcRegionFreeingVerbose) {
6357 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6358 "done waiting for free regions");
6359 }
6360 }
6361
6362 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6363 assert(heap_lock_held_for_gc(),
6364 "the heap lock should already be held by or for this thread");
6365 _young_list->push_region(hr);
6366 }
6367
6368 class NoYoungRegionsClosure: public HeapRegionClosure {
6369 private:
6370 bool _success;
6371 public:
6372 NoYoungRegionsClosure() : _success(true) { }
6373 bool doHeapRegion(HeapRegion* r) {
6374 if (r->is_young()) {
6375 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6376 r->bottom(), r->end());
6377 _success = false;
6378 }
6379 return false;
6380 }
6381 bool success() { return _success; }
6382 };
6383
6384 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6385 bool ret = _young_list->check_list_empty(check_sample);
6386
6387 if (check_heap) {
6388 NoYoungRegionsClosure closure;
6389 heap_region_iterate(&closure);
6390 ret = ret && closure.success();
6391 }
6392
6393 return ret;
6394 }
6395
6396 class TearDownRegionSetsClosure : public HeapRegionClosure {
6397 private:
6398 HeapRegionSet *_old_set;
6399
6400 public:
6401 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6402
6403 bool doHeapRegion(HeapRegion* r) {
6404 if (r->is_old()) {
6405 _old_set->remove(r);
6406 } else {
6407 // We ignore free regions, we'll empty the free list afterwards.
6408 // We ignore young regions, we'll empty the young list afterwards.
6409 // We ignore humongous regions, we're not tearing down the
6410 // humongous regions set.
6411 assert(r->is_free() || r->is_young() || r->is_humongous(),
6412 "it cannot be another type");
6413 }
6414 return false;
6415 }
6416
6417 ~TearDownRegionSetsClosure() {
6418 assert(_old_set->is_empty(), "post-condition");
6419 }
6420 };
6421
6422 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6423 assert_at_safepoint(true /* should_be_vm_thread */);
6424
6425 if (!free_list_only) {
6426 TearDownRegionSetsClosure cl(&_old_set);
6427 heap_region_iterate(&cl);
6428
6429 // Note that emptying the _young_list is postponed and instead done as
6430 // the first step when rebuilding the regions sets again. The reason for
6431 // this is that during a full GC string deduplication needs to know if
6432 // a collected region was young or old when the full GC was initiated.
6433 }
6434 _hrm.remove_all_free_regions();
6435 }
6436
6437 class RebuildRegionSetsClosure : public HeapRegionClosure {
6438 private:
6439 bool _free_list_only;
6440 HeapRegionSet* _old_set;
6441 HeapRegionManager* _hrm;
6442 size_t _total_used;
6443
6444 public:
6445 RebuildRegionSetsClosure(bool free_list_only,
6446 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6447 _free_list_only(free_list_only),
6448 _old_set(old_set), _hrm(hrm), _total_used(0) {
6449 assert(_hrm->num_free_regions() == 0, "pre-condition");
6450 if (!free_list_only) {
6451 assert(_old_set->is_empty(), "pre-condition");
6452 }
6453 }
6454
6455 bool doHeapRegion(HeapRegion* r) {
6456 if (r->is_continues_humongous()) {
6457 return false;
6458 }
6459
6460 if (r->is_empty()) {
6461 // Add free regions to the free list
6462 r->set_free();
6463 r->set_allocation_context(AllocationContext::system());
6464 _hrm->insert_into_free_list(r);
6465 } else if (!_free_list_only) {
6466 assert(!r->is_young(), "we should not come across young regions");
6467
6468 if (r->is_humongous()) {
6469 // We ignore humongous regions, we left the humongous set unchanged
6470 } else {
6471 // Objects that were compacted would have ended up on regions
6472 // that were previously old or free.
6473 assert(r->is_free() || r->is_old(), "invariant");
6474 // We now consider them old, so register as such.
6475 r->set_old();
6476 _old_set->add(r);
6477 }
6478 _total_used += r->used();
6479 }
6480
6481 return false;
6482 }
6483
6484 size_t total_used() {
6485 return _total_used;
6486 }
6487 };
6488
6489 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6490 assert_at_safepoint(true /* should_be_vm_thread */);
6491
6492 if (!free_list_only) {
6493 _young_list->empty_list();
6494 }
6495
6496 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6497 heap_region_iterate(&cl);
6498
6499 if (!free_list_only) {
6500 _allocator->set_used(cl.total_used());
6501 }
6502 assert(_allocator->used_unlocked() == recalculate_used(),
6503 err_msg("inconsistent _allocator->used_unlocked(), "
6504 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6505 _allocator->used_unlocked(), recalculate_used()));
6506 }
6507
6508 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6509 _refine_cte_cl->set_concurrent(concurrent);
6510 }
6511
6512 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6513 HeapRegion* hr = heap_region_containing(p);
6514 return hr->is_in(p);
6515 }
6516
6517 // Methods for the mutator alloc region
6518
6519 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6520 bool force) {
6521 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6522 assert(!force || g1_policy()->can_expand_young_list(),
6523 "if force is true we should be able to expand the young list");
6524 bool young_list_full = g1_policy()->is_young_list_full();
6525 if (force || !young_list_full) {
6526 HeapRegion* new_alloc_region = new_region(word_size,
6527 false /* is_old */,
6528 false /* do_expand */);
6529 if (new_alloc_region != NULL) {
6530 set_region_short_lived_locked(new_alloc_region);
6531 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6532 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6533 return new_alloc_region;
6534 }
6535 }
6536 return NULL;
6537 }
6538
6539 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6540 size_t allocated_bytes) {
6541 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6542 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6543
6544 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6545 _allocator->increase_used(allocated_bytes);
6546 _hr_printer.retire(alloc_region);
6547 // We update the eden sizes here, when the region is retired,
6548 // instead of when it's allocated, since this is the point that its
6549 // used space has been recored in _summary_bytes_used.
6550 g1mm()->update_eden_size();
6551 }
6552
6553 void G1CollectedHeap::set_par_threads() {
6554 // Don't change the number of workers. Use the value previously set
6555 // in the workgroup.
6556 uint n_workers = workers()->active_workers();
6557 assert(UseDynamicNumberOfGCThreads ||
6558 n_workers == workers()->total_workers(),
6559 "Otherwise should be using the total number of workers");
6560 if (n_workers == 0) {
6561 assert(false, "Should have been set in prior evacuation pause.");
6562 n_workers = ParallelGCThreads;
6563 workers()->set_active_workers(n_workers);
6564 }
6565 set_par_threads(n_workers);
6566 }
6567
6568 // Methods for the GC alloc regions
6569
6570 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6571 uint count,
6572 InCSetState dest) {
6573 assert(FreeList_lock->owned_by_self(), "pre-condition");
6574
6575 if (count < g1_policy()->max_regions(dest)) {
6576 const bool is_survivor = (dest.is_young());
6577 HeapRegion* new_alloc_region = new_region(word_size,
6578 !is_survivor,
6579 true /* do_expand */);
6580 if (new_alloc_region != NULL) {
6581 // We really only need to do this for old regions given that we
6582 // should never scan survivors. But it doesn't hurt to do it
6583 // for survivors too.
6584 new_alloc_region->record_timestamp();
6585 if (is_survivor) {
6586 new_alloc_region->set_survivor();
6587 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6588 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6589 } else {
6590 new_alloc_region->set_old();
6591 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6592 check_bitmaps("Old Region Allocation", new_alloc_region);
6593 }
6594 bool during_im = g1_policy()->during_initial_mark_pause();
6595 new_alloc_region->note_start_of_copying(during_im);
6596 return new_alloc_region;
6597 }
6598 }
6599 return NULL;
6600 }
6601
6602 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6603 size_t allocated_bytes,
6604 InCSetState dest) {
6605 bool during_im = g1_policy()->during_initial_mark_pause();
6606 alloc_region->note_end_of_copying(during_im);
6607 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6608 if (dest.is_young()) {
6609 young_list()->add_survivor_region(alloc_region);
6610 } else {
6611 _old_set.add(alloc_region);
6612 }
6613 _hr_printer.retire(alloc_region);
6614 }
6615
6616 // Heap region set verification
6617
6618 class VerifyRegionListsClosure : public HeapRegionClosure {
6619 private:
6620 HeapRegionSet* _old_set;
6621 HeapRegionSet* _humongous_set;
6622 HeapRegionManager* _hrm;
6623
6624 public:
6625 HeapRegionSetCount _old_count;
6626 HeapRegionSetCount _humongous_count;
6627 HeapRegionSetCount _free_count;
6628
6629 VerifyRegionListsClosure(HeapRegionSet* old_set,
6630 HeapRegionSet* humongous_set,
6631 HeapRegionManager* hrm) :
6632 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6633 _old_count(), _humongous_count(), _free_count(){ }
6634
6635 bool doHeapRegion(HeapRegion* hr) {
6636 if (hr->is_continues_humongous()) {
6637 return false;
6638 }
6639
6640 if (hr->is_young()) {
6641 // TODO
6642 } else if (hr->is_starts_humongous()) {
6643 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6644 _humongous_count.increment(1u, hr->capacity());
6645 } else if (hr->is_empty()) {
6646 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6647 _free_count.increment(1u, hr->capacity());
6648 } else if (hr->is_old()) {
6649 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6650 _old_count.increment(1u, hr->capacity());
6651 } else {
6652 ShouldNotReachHere();
6653 }
6654 return false;
6655 }
6656
6657 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6658 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6659 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6660 old_set->total_capacity_bytes(), _old_count.capacity()));
6661
6662 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6663 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6664 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6665
6666 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()));
6667 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6668 free_list->total_capacity_bytes(), _free_count.capacity()));
6669 }
6670 };
6671
6672 void G1CollectedHeap::verify_region_sets() {
6673 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6674
6675 // First, check the explicit lists.
6676 _hrm.verify();
6677 {
6678 // Given that a concurrent operation might be adding regions to
6679 // the secondary free list we have to take the lock before
6680 // verifying it.
6681 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6682 _secondary_free_list.verify_list();
6683 }
6684
6685 // If a concurrent region freeing operation is in progress it will
6686 // be difficult to correctly attributed any free regions we come
6687 // across to the correct free list given that they might belong to
6688 // one of several (free_list, secondary_free_list, any local lists,
6689 // etc.). So, if that's the case we will skip the rest of the
6690 // verification operation. Alternatively, waiting for the concurrent
6691 // operation to complete will have a non-trivial effect on the GC's
6692 // operation (no concurrent operation will last longer than the
6693 // interval between two calls to verification) and it might hide
6694 // any issues that we would like to catch during testing.
6695 if (free_regions_coming()) {
6696 return;
6697 }
6698
6699 // Make sure we append the secondary_free_list on the free_list so
6700 // that all free regions we will come across can be safely
6701 // attributed to the free_list.
6702 append_secondary_free_list_if_not_empty_with_lock();
6703
6704 // Finally, make sure that the region accounting in the lists is
6705 // consistent with what we see in the heap.
6706
6707 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6708 heap_region_iterate(&cl);
6709 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6710 }
6711
6712 // Optimized nmethod scanning
6713
6714 class RegisterNMethodOopClosure: public OopClosure {
6715 G1CollectedHeap* _g1h;
6716 nmethod* _nm;
6717
6718 template <class T> void do_oop_work(T* p) {
6719 T heap_oop = oopDesc::load_heap_oop(p);
6720 if (!oopDesc::is_null(heap_oop)) {
6721 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6722 HeapRegion* hr = _g1h->heap_region_containing(obj);
6723 assert(!hr->is_continues_humongous(),
6724 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6725 " starting at "HR_FORMAT,
6726 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6727
6728 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6729 hr->add_strong_code_root_locked(_nm);
6730 }
6731 }
6732
6733 public:
6734 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6735 _g1h(g1h), _nm(nm) {}
6736
6737 void do_oop(oop* p) { do_oop_work(p); }
6738 void do_oop(narrowOop* p) { do_oop_work(p); }
6739 };
6740
6741 class UnregisterNMethodOopClosure: public OopClosure {
6742 G1CollectedHeap* _g1h;
6743 nmethod* _nm;
6744
6745 template <class T> void do_oop_work(T* p) {
6746 T heap_oop = oopDesc::load_heap_oop(p);
6747 if (!oopDesc::is_null(heap_oop)) {
6748 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6749 HeapRegion* hr = _g1h->heap_region_containing(obj);
6750 assert(!hr->is_continues_humongous(),
6751 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6752 " starting at "HR_FORMAT,
6753 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6754
6755 hr->remove_strong_code_root(_nm);
6756 }
6757 }
6758
6759 public:
6760 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6761 _g1h(g1h), _nm(nm) {}
6762
6763 void do_oop(oop* p) { do_oop_work(p); }
6764 void do_oop(narrowOop* p) { do_oop_work(p); }
6765 };
6766
6767 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6768 CollectedHeap::register_nmethod(nm);
6769
6770 guarantee(nm != NULL, "sanity");
6771 RegisterNMethodOopClosure reg_cl(this, nm);
6772 nm->oops_do(®_cl);
6773 }
6774
6775 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6776 CollectedHeap::unregister_nmethod(nm);
6777
6778 guarantee(nm != NULL, "sanity");
6779 UnregisterNMethodOopClosure reg_cl(this, nm);
6780 nm->oops_do(®_cl, true);
6781 }
6782
6783 void G1CollectedHeap::purge_code_root_memory() {
6784 double purge_start = os::elapsedTime();
6785 G1CodeRootSet::purge();
6786 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6787 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6788 }
6789
6790 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6791 G1CollectedHeap* _g1h;
6792
6793 public:
6794 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6795 _g1h(g1h) {}
6796
6797 void do_code_blob(CodeBlob* cb) {
6798 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6799 if (nm == NULL) {
6800 return;
6801 }
6802
6803 if (ScavengeRootsInCode) {
6804 _g1h->register_nmethod(nm);
6805 }
6806 }
6807 };
6808
6809 void G1CollectedHeap::rebuild_strong_code_roots() {
6810 RebuildStrongCodeRootClosure blob_cl(this);
6811 CodeCache::blobs_do(&blob_cl);
6812 }