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 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1AllocRegion.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1ErgoVerbose.hpp"
38 #include "gc/g1/g1EvacFailure.hpp"
39 #include "gc/g1/g1GCPhaseTimes.hpp"
40 #include "gc/g1/g1Log.hpp"
41 #include "gc/g1/g1MarkSweep.hpp"
42 #include "gc/g1/g1OopClosures.inline.hpp"
43 #include "gc/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc/g1/g1RemSet.inline.hpp"
46 #include "gc/g1/g1RootProcessor.hpp"
47 #include "gc/g1/g1StringDedup.hpp"
48 #include "gc/g1/g1YCTypes.hpp"
49 #include "gc/g1/heapRegion.inline.hpp"
50 #include "gc/g1/heapRegionRemSet.hpp"
51 #include "gc/g1/heapRegionSet.inline.hpp"
52 #include "gc/g1/suspendibleThreadSet.hpp"
53 #include "gc/g1/vm_operations_g1.hpp"
54 #include "gc/shared/gcHeapSummary.hpp"
55 #include "gc/shared/gcLocker.inline.hpp"
56 #include "gc/shared/gcTimer.hpp"
57 #include "gc/shared/gcTrace.hpp"
58 #include "gc/shared/gcTraceTime.hpp"
59 #include "gc/shared/generationSpec.hpp"
60 #include "gc/shared/isGCActiveMark.hpp"
61 #include "gc/shared/referenceProcessor.hpp"
62 #include "gc/shared/taskqueue.inline.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/iterator.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "runtime/atomic.inline.hpp"
67 #include "runtime/orderAccess.inline.hpp"
68 #include "runtime/vmThread.hpp"
69 #include "utilities/globalDefinitions.hpp"
70 #include "utilities/stack.inline.hpp"
71
72 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
73
74 // turn it on so that the contents of the young list (scan-only /
75 // to-be-collected) are printed at "strategic" points before / during
76 // / after the collection --- this is useful for debugging
77 #define YOUNG_LIST_VERBOSE 0
78 // CURRENT STATUS
79 // This file is under construction. Search for "FIXME".
80
81 // INVARIANTS/NOTES
82 //
83 // All allocation activity covered by the G1CollectedHeap interface is
84 // serialized by acquiring the HeapLock. This happens in mem_allocate
85 // and allocate_new_tlab, which are the "entry" points to the
86 // allocation code from the rest of the JVM. (Note that this does not
87 // apply to TLAB allocation, which is not part of this interface: it
88 // is done by clients of this interface.)
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 bool _concurrent;
94 public:
95 RefineCardTableEntryClosure() : _concurrent(true) { }
96
97 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
98 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
99 // This path is executed by the concurrent refine or mutator threads,
100 // concurrently, and so we do not care if card_ptr contains references
101 // that point into the collection set.
102 assert(!oops_into_cset, "should be");
103
104 if (_concurrent && SuspendibleThreadSet::should_yield()) {
105 // Caller will actually yield.
106 return false;
107 }
108 // Otherwise, we finished successfully; return true.
109 return true;
110 }
111
112 void set_concurrent(bool b) { _concurrent = b; }
113 };
114
115
116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
117 private:
118 size_t _num_processed;
119
120 public:
121 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
122
123 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
124 *card_ptr = CardTableModRefBS::dirty_card_val();
125 _num_processed++;
126 return true;
127 }
128
129 size_t num_processed() const { return _num_processed; }
130 };
131
132 YoungList::YoungList(G1CollectedHeap* g1h) :
133 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
134 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
135 guarantee(check_list_empty(false), "just making sure...");
136 }
137
138 void YoungList::push_region(HeapRegion *hr) {
139 assert(!hr->is_young(), "should not already be young");
140 assert(hr->get_next_young_region() == NULL, "cause it should!");
141
142 hr->set_next_young_region(_head);
143 _head = hr;
144
145 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
146 ++_length;
147 }
148
149 void YoungList::add_survivor_region(HeapRegion* hr) {
150 assert(hr->is_survivor(), "should be flagged as survivor region");
151 assert(hr->get_next_young_region() == NULL, "cause it should!");
152
153 hr->set_next_young_region(_survivor_head);
154 if (_survivor_head == NULL) {
155 _survivor_tail = hr;
156 }
157 _survivor_head = hr;
158 ++_survivor_length;
159 }
160
161 void YoungList::empty_list(HeapRegion* list) {
162 while (list != NULL) {
163 HeapRegion* next = list->get_next_young_region();
164 list->set_next_young_region(NULL);
165 list->uninstall_surv_rate_group();
166 // This is called before a Full GC and all the non-empty /
167 // non-humongous regions at the end of the Full GC will end up as
168 // old anyway.
169 list->set_old();
170 list = next;
171 }
172 }
173
174 void YoungList::empty_list() {
175 assert(check_list_well_formed(), "young list should be well formed");
176
177 empty_list(_head);
178 _head = NULL;
179 _length = 0;
180
181 empty_list(_survivor_head);
182 _survivor_head = NULL;
183 _survivor_tail = NULL;
184 _survivor_length = 0;
185
186 _last_sampled_rs_lengths = 0;
187
188 assert(check_list_empty(false), "just making sure...");
189 }
190
191 bool YoungList::check_list_well_formed() {
192 bool ret = true;
193
194 uint length = 0;
195 HeapRegion* curr = _head;
196 HeapRegion* last = NULL;
197 while (curr != NULL) {
198 if (!curr->is_young()) {
199 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
200 "incorrectly tagged (y: %d, surv: %d)",
201 p2i(curr->bottom()), p2i(curr->end()),
202 curr->is_young(), curr->is_survivor());
203 ret = false;
204 }
205 ++length;
206 last = curr;
207 curr = curr->get_next_young_region();
208 }
209 ret = ret && (length == _length);
210
211 if (!ret) {
212 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
213 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
214 length, _length);
215 }
216
217 return ret;
218 }
219
220 bool YoungList::check_list_empty(bool check_sample) {
221 bool ret = true;
222
223 if (_length != 0) {
224 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
225 _length);
226 ret = false;
227 }
228 if (check_sample && _last_sampled_rs_lengths != 0) {
229 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
230 ret = false;
231 }
232 if (_head != NULL) {
233 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
234 ret = false;
235 }
236 if (!ret) {
237 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
238 }
239
240 return ret;
241 }
242
243 void
244 YoungList::rs_length_sampling_init() {
245 _sampled_rs_lengths = 0;
246 _curr = _head;
247 }
248
249 bool
250 YoungList::rs_length_sampling_more() {
251 return _curr != NULL;
252 }
253
254 void
255 YoungList::rs_length_sampling_next() {
256 assert( _curr != NULL, "invariant" );
257 size_t rs_length = _curr->rem_set()->occupied();
258
259 _sampled_rs_lengths += rs_length;
260
261 // The current region may not yet have been added to the
262 // incremental collection set (it gets added when it is
263 // retired as the current allocation region).
264 if (_curr->in_collection_set()) {
265 // Update the collection set policy information for this region
266 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
267 }
268
269 _curr = _curr->get_next_young_region();
270 if (_curr == NULL) {
271 _last_sampled_rs_lengths = _sampled_rs_lengths;
272 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
273 }
274 }
275
276 void
277 YoungList::reset_auxilary_lists() {
278 guarantee( is_empty(), "young list should be empty" );
279 assert(check_list_well_formed(), "young list should be well formed");
280
281 // Add survivor regions to SurvRateGroup.
282 _g1h->g1_policy()->note_start_adding_survivor_regions();
283 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
284
285 int young_index_in_cset = 0;
286 for (HeapRegion* curr = _survivor_head;
287 curr != NULL;
288 curr = curr->get_next_young_region()) {
289 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
290
291 // The region is a non-empty survivor so let's add it to
292 // the incremental collection set for the next evacuation
293 // pause.
294 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
295 young_index_in_cset += 1;
296 }
297 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
298 _g1h->g1_policy()->note_stop_adding_survivor_regions();
299
300 _head = _survivor_head;
301 _length = _survivor_length;
302 if (_survivor_head != NULL) {
303 assert(_survivor_tail != NULL, "cause it shouldn't be");
304 assert(_survivor_length > 0, "invariant");
305 _survivor_tail->set_next_young_region(NULL);
306 }
307
308 // Don't clear the survivor list handles until the start of
309 // the next evacuation pause - we need it in order to re-tag
310 // the survivor regions from this evacuation pause as 'young'
311 // at the start of the next.
312
313 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
314
315 assert(check_list_well_formed(), "young list should be well formed");
316 }
317
318 void YoungList::print() {
319 HeapRegion* lists[] = {_head, _survivor_head};
320 const char* names[] = {"YOUNG", "SURVIVOR"};
321
322 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
323 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
324 HeapRegion *curr = lists[list];
325 if (curr == NULL)
326 gclog_or_tty->print_cr(" empty");
327 while (curr != NULL) {
328 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
329 HR_FORMAT_PARAMS(curr),
330 p2i(curr->prev_top_at_mark_start()),
331 p2i(curr->next_top_at_mark_start()),
332 curr->age_in_surv_rate_group_cond());
333 curr = curr->get_next_young_region();
334 }
335 }
336
337 gclog_or_tty->cr();
338 }
339
340 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
341 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
342 }
343
344 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
345 // The from card cache is not the memory that is actually committed. So we cannot
346 // take advantage of the zero_filled parameter.
347 reset_from_card_cache(start_idx, num_regions);
348 }
349
350 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
351 {
352 // Claim the right to put the region on the dirty cards region list
353 // by installing a self pointer.
354 HeapRegion* next = hr->get_next_dirty_cards_region();
355 if (next == NULL) {
356 HeapRegion* res = (HeapRegion*)
357 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
358 NULL);
359 if (res == NULL) {
360 HeapRegion* head;
361 do {
362 // Put the region to the dirty cards region list.
363 head = _dirty_cards_region_list;
364 next = (HeapRegion*)
365 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
366 if (next == head) {
367 assert(hr->get_next_dirty_cards_region() == hr,
368 "hr->get_next_dirty_cards_region() != hr");
369 if (next == NULL) {
370 // The last region in the list points to itself.
371 hr->set_next_dirty_cards_region(hr);
372 } else {
373 hr->set_next_dirty_cards_region(next);
374 }
375 }
376 } while (next != head);
377 }
378 }
379 }
380
381 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
382 {
383 HeapRegion* head;
384 HeapRegion* hr;
385 do {
386 head = _dirty_cards_region_list;
387 if (head == NULL) {
388 return NULL;
389 }
390 HeapRegion* new_head = head->get_next_dirty_cards_region();
391 if (head == new_head) {
392 // The last region.
393 new_head = NULL;
394 }
395 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
396 head);
397 } while (hr != head);
398 assert(hr != NULL, "invariant");
399 hr->set_next_dirty_cards_region(NULL);
400 return hr;
401 }
402
403 // Returns true if the reference points to an object that
404 // can move in an incremental collection.
405 bool G1CollectedHeap::is_scavengable(const void* p) {
406 HeapRegion* hr = heap_region_containing(p);
407 return !hr->is_pinned();
408 }
409
410 // Private methods.
411
412 HeapRegion*
413 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
414 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
415 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
416 if (!_secondary_free_list.is_empty()) {
417 if (G1ConcRegionFreeingVerbose) {
418 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
419 "secondary_free_list has %u entries",
420 _secondary_free_list.length());
421 }
422 // It looks as if there are free regions available on the
423 // secondary_free_list. Let's move them to the free_list and try
424 // again to allocate from it.
425 append_secondary_free_list();
426
427 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
428 "empty we should have moved at least one entry to the free_list");
429 HeapRegion* res = _hrm.allocate_free_region(is_old);
430 if (G1ConcRegionFreeingVerbose) {
431 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
432 "allocated "HR_FORMAT" from secondary_free_list",
433 HR_FORMAT_PARAMS(res));
434 }
435 return res;
436 }
437
438 // Wait here until we get notified either when (a) there are no
439 // more free regions coming or (b) some regions have been moved on
440 // the secondary_free_list.
441 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
442 }
443
444 if (G1ConcRegionFreeingVerbose) {
445 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
446 "could not allocate from secondary_free_list");
447 }
448 return NULL;
449 }
450
451 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
452 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
453 "the only time we use this to allocate a humongous region is "
454 "when we are allocating a single humongous region");
455
456 HeapRegion* res;
457 if (G1StressConcRegionFreeing) {
458 if (!_secondary_free_list.is_empty()) {
459 if (G1ConcRegionFreeingVerbose) {
460 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
461 "forced to look at the secondary_free_list");
462 }
463 res = new_region_try_secondary_free_list(is_old);
464 if (res != NULL) {
465 return res;
466 }
467 }
468 }
469
470 res = _hrm.allocate_free_region(is_old);
471
472 if (res == NULL) {
473 if (G1ConcRegionFreeingVerbose) {
474 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
475 "res == NULL, trying the secondary_free_list");
476 }
477 res = new_region_try_secondary_free_list(is_old);
478 }
479 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
480 // Currently, only attempts to allocate GC alloc regions set
481 // do_expand to true. So, we should only reach here during a
482 // safepoint. If this assumption changes we might have to
483 // reconsider the use of _expand_heap_after_alloc_failure.
484 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
485
486 ergo_verbose1(ErgoHeapSizing,
487 "attempt heap expansion",
488 ergo_format_reason("region allocation request failed")
489 ergo_format_byte("allocation request"),
490 word_size * HeapWordSize);
491 if (expand(word_size * HeapWordSize)) {
492 // Given that expand() succeeded in expanding the heap, and we
493 // always expand the heap by an amount aligned to the heap
494 // region size, the free list should in theory not be empty.
495 // In either case allocate_free_region() will check for NULL.
496 res = _hrm.allocate_free_region(is_old);
497 } else {
498 _expand_heap_after_alloc_failure = false;
499 }
500 }
501 return res;
502 }
503
504 HeapWord*
505 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
506 uint num_regions,
507 size_t word_size,
508 AllocationContext_t context) {
509 assert(first != G1_NO_HRM_INDEX, "pre-condition");
510 assert(is_humongous(word_size), "word_size should be humongous");
511 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
512
513 // Index of last region in the series + 1.
514 uint last = first + num_regions;
515
516 // We need to initialize the region(s) we just discovered. This is
517 // a bit tricky given that it can happen concurrently with
518 // refinement threads refining cards on these regions and
519 // potentially wanting to refine the BOT as they are scanning
520 // those cards (this can happen shortly after a cleanup; see CR
521 // 6991377). So we have to set up the region(s) carefully and in
522 // a specific order.
523
524 // The word size sum of all the regions we will allocate.
525 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
526 assert(word_size <= word_size_sum, "sanity");
527
528 // This will be the "starts humongous" region.
529 HeapRegion* first_hr = region_at(first);
530 // The header of the new object will be placed at the bottom of
531 // the first region.
532 HeapWord* new_obj = first_hr->bottom();
533 // This will be the new end of the first region in the series that
534 // should also match the end of the last region in the series.
535 HeapWord* new_end = new_obj + word_size_sum;
536 // This will be the new top of the first region that will reflect
537 // this allocation.
538 HeapWord* new_top = new_obj + word_size;
539
540 // First, we need to zero the header of the space that we will be
541 // allocating. When we update top further down, some refinement
542 // threads might try to scan the region. By zeroing the header we
543 // ensure that any thread that will try to scan the region will
544 // come across the zero klass word and bail out.
545 //
546 // NOTE: It would not have been correct to have used
547 // CollectedHeap::fill_with_object() and make the space look like
548 // an int array. The thread that is doing the allocation will
549 // later update the object header to a potentially different array
550 // type and, for a very short period of time, the klass and length
551 // fields will be inconsistent. This could cause a refinement
552 // thread to calculate the object size incorrectly.
553 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
554
555 // We will set up the first region as "starts humongous". This
556 // will also update the BOT covering all the regions to reflect
557 // that there is a single object that starts at the bottom of the
558 // first region.
559 first_hr->set_starts_humongous(new_top, new_end);
560 first_hr->set_allocation_context(context);
561 // Then, if there are any, we will set up the "continues
562 // humongous" regions.
563 HeapRegion* hr = NULL;
564 for (uint i = first + 1; i < last; ++i) {
565 hr = region_at(i);
566 hr->set_continues_humongous(first_hr);
567 hr->set_allocation_context(context);
568 }
569 // If we have "continues humongous" regions (hr != NULL), then the
570 // end of the last one should match new_end.
571 assert(hr == NULL || hr->end() == new_end, "sanity");
572
573 // Up to this point no concurrent thread would have been able to
574 // do any scanning on any region in this series. All the top
575 // fields still point to bottom, so the intersection between
576 // [bottom,top] and [card_start,card_end] will be empty. Before we
577 // update the top fields, we'll do a storestore to make sure that
578 // no thread sees the update to top before the zeroing of the
579 // object header and the BOT initialization.
580 OrderAccess::storestore();
581
582 // Now that the BOT and the object header have been initialized,
583 // we can update top of the "starts humongous" region.
584 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
585 "new_top should be in this region");
586 first_hr->set_top(new_top);
587 if (_hr_printer.is_active()) {
588 HeapWord* bottom = first_hr->bottom();
589 HeapWord* end = first_hr->orig_end();
590 if ((first + 1) == last) {
591 // the series has a single humongous region
592 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
593 } else {
594 // the series has more than one humongous regions
595 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
596 }
597 }
598
599 // Now, we will update the top fields of the "continues humongous"
600 // regions. The reason we need to do this is that, otherwise,
601 // these regions would look empty and this will confuse parts of
602 // G1. For example, the code that looks for a consecutive number
603 // of empty regions will consider them empty and try to
604 // re-allocate them. We can extend is_empty() to also include
605 // !is_continues_humongous(), but it is easier to just update the top
606 // fields here. The way we set top for all regions (i.e., top ==
607 // end for all regions but the last one, top == new_top for the
608 // last one) is actually used when we will free up the humongous
609 // region in free_humongous_region().
610 hr = NULL;
611 for (uint i = first + 1; i < last; ++i) {
612 hr = region_at(i);
613 if ((i + 1) == last) {
614 // last continues humongous region
615 assert(hr->bottom() < new_top && new_top <= hr->end(),
616 "new_top should fall on this region");
617 hr->set_top(new_top);
618 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
619 } else {
620 // not last one
621 assert(new_top > hr->end(), "new_top should be above this region");
622 hr->set_top(hr->end());
623 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
624 }
625 }
626 // If we have continues humongous regions (hr != NULL), then the
627 // end of the last one should match new_end and its top should
628 // match new_top.
629 assert(hr == NULL ||
630 (hr->end() == new_end && hr->top() == new_top), "sanity");
631 check_bitmaps("Humongous Region Allocation", first_hr);
632
633 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
634 _allocator->increase_used(first_hr->used());
635 _humongous_set.add(first_hr);
636
637 return new_obj;
638 }
639
640 // If could fit into free regions w/o expansion, try.
641 // Otherwise, if can expand, do so.
642 // Otherwise, if using ex regions might help, try with ex given back.
643 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
644 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
645
646 verify_region_sets_optional();
647
648 uint first = G1_NO_HRM_INDEX;
649 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
650
651 if (obj_regions == 1) {
652 // Only one region to allocate, try to use a fast path by directly allocating
653 // from the free lists. Do not try to expand here, we will potentially do that
654 // later.
655 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
656 if (hr != NULL) {
657 first = hr->hrm_index();
658 }
659 } else {
660 // We can't allocate humongous regions spanning more than one region while
661 // cleanupComplete() is running, since some of the regions we find to be
662 // empty might not yet be added to the free list. It is not straightforward
663 // to know in which list they are on so that we can remove them. We only
664 // need to do this if we need to allocate more than one region to satisfy the
665 // current humongous allocation request. If we are only allocating one region
666 // we use the one-region region allocation code (see above), that already
667 // potentially waits for regions from the secondary free list.
668 wait_while_free_regions_coming();
669 append_secondary_free_list_if_not_empty_with_lock();
670
671 // Policy: Try only empty regions (i.e. already committed first). Maybe we
672 // are lucky enough to find some.
673 first = _hrm.find_contiguous_only_empty(obj_regions);
674 if (first != G1_NO_HRM_INDEX) {
675 _hrm.allocate_free_regions_starting_at(first, obj_regions);
676 }
677 }
678
679 if (first == G1_NO_HRM_INDEX) {
680 // Policy: We could not find enough regions for the humongous object in the
681 // free list. Look through the heap to find a mix of free and uncommitted regions.
682 // If so, try expansion.
683 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
684 if (first != G1_NO_HRM_INDEX) {
685 // We found something. Make sure these regions are committed, i.e. expand
686 // the heap. Alternatively we could do a defragmentation GC.
687 ergo_verbose1(ErgoHeapSizing,
688 "attempt heap expansion",
689 ergo_format_reason("humongous allocation request failed")
690 ergo_format_byte("allocation request"),
691 word_size * HeapWordSize);
692
693 _hrm.expand_at(first, obj_regions);
694 g1_policy()->record_new_heap_size(num_regions());
695
696 #ifdef ASSERT
697 for (uint i = first; i < first + obj_regions; ++i) {
698 HeapRegion* hr = region_at(i);
699 assert(hr->is_free(), "sanity");
700 assert(hr->is_empty(), "sanity");
701 assert(is_on_master_free_list(hr), "sanity");
702 }
703 #endif
704 _hrm.allocate_free_regions_starting_at(first, obj_regions);
705 } else {
706 // Policy: Potentially trigger a defragmentation GC.
707 }
708 }
709
710 HeapWord* result = NULL;
711 if (first != G1_NO_HRM_INDEX) {
712 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
713 word_size, context);
714 assert(result != NULL, "it should always return a valid result");
715
716 // A successful humongous object allocation changes the used space
717 // information of the old generation so we need to recalculate the
718 // sizes and update the jstat counters here.
719 g1mm()->update_sizes();
720 }
721
722 verify_region_sets_optional();
723
724 return result;
725 }
726
727 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
728 assert_heap_not_locked_and_not_at_safepoint();
729 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
730
731 uint dummy_gc_count_before;
732 uint dummy_gclocker_retry_count = 0;
733 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
734 }
735
736 HeapWord*
737 G1CollectedHeap::mem_allocate(size_t word_size,
738 bool* gc_overhead_limit_was_exceeded) {
739 assert_heap_not_locked_and_not_at_safepoint();
740
741 // Loop until the allocation is satisfied, or unsatisfied after GC.
742 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
743 uint gc_count_before;
744
745 HeapWord* result = NULL;
746 if (!is_humongous(word_size)) {
747 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
748 } else {
749 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
750 }
751 if (result != NULL) {
752 return result;
753 }
754
755 // Create the garbage collection operation...
756 VM_G1CollectForAllocation op(gc_count_before, word_size);
757 op.set_allocation_context(AllocationContext::current());
758
759 // ...and get the VM thread to execute it.
760 VMThread::execute(&op);
761
762 if (op.prologue_succeeded() && op.pause_succeeded()) {
763 // If the operation was successful we'll return the result even
764 // if it is NULL. If the allocation attempt failed immediately
765 // after a Full GC, it's unlikely we'll be able to allocate now.
766 HeapWord* result = op.result();
767 if (result != NULL && !is_humongous(word_size)) {
768 // Allocations that take place on VM operations do not do any
769 // card dirtying and we have to do it here. We only have to do
770 // this for non-humongous allocations, though.
771 dirty_young_block(result, word_size);
772 }
773 return result;
774 } else {
775 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
776 return NULL;
777 }
778 assert(op.result() == NULL,
779 "the result should be NULL if the VM op did not succeed");
780 }
781
782 // Give a warning if we seem to be looping forever.
783 if ((QueuedAllocationWarningCount > 0) &&
784 (try_count % QueuedAllocationWarningCount == 0)) {
785 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
786 }
787 }
788
789 ShouldNotReachHere();
790 return NULL;
791 }
792
793 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
794 AllocationContext_t context,
795 uint* gc_count_before_ret,
796 uint* gclocker_retry_count_ret) {
797 // Make sure you read the note in attempt_allocation_humongous().
798
799 assert_heap_not_locked_and_not_at_safepoint();
800 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
801 "be called for humongous allocation requests");
802
803 // We should only get here after the first-level allocation attempt
804 // (attempt_allocation()) failed to allocate.
805
806 // We will loop until a) we manage to successfully perform the
807 // allocation or b) we successfully schedule a collection which
808 // fails to perform the allocation. b) is the only case when we'll
809 // return NULL.
810 HeapWord* result = NULL;
811 for (int try_count = 1; /* we'll return */; try_count += 1) {
812 bool should_try_gc;
813 uint gc_count_before;
814
815 {
816 MutexLockerEx x(Heap_lock);
817 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
818 false /* bot_updates */);
819 if (result != NULL) {
820 return result;
821 }
822
823 // If we reach here, attempt_allocation_locked() above failed to
824 // allocate a new region. So the mutator alloc region should be NULL.
825 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
826
827 if (GC_locker::is_active_and_needs_gc()) {
828 if (g1_policy()->can_expand_young_list()) {
829 // No need for an ergo verbose message here,
830 // can_expand_young_list() does this when it returns true.
831 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
832 false /* bot_updates */);
833 if (result != NULL) {
834 return result;
835 }
836 }
837 should_try_gc = false;
838 } else {
839 // The GCLocker may not be active but the GCLocker initiated
840 // GC may not yet have been performed (GCLocker::needs_gc()
841 // returns true). In this case we do not try this GC and
842 // wait until the GCLocker initiated GC is performed, and
843 // then retry the allocation.
844 if (GC_locker::needs_gc()) {
845 should_try_gc = false;
846 } else {
847 // Read the GC count while still holding the Heap_lock.
848 gc_count_before = total_collections();
849 should_try_gc = true;
850 }
851 }
852 }
853
854 if (should_try_gc) {
855 bool succeeded;
856 result = do_collection_pause(word_size, gc_count_before, &succeeded,
857 GCCause::_g1_inc_collection_pause);
858 if (result != NULL) {
859 assert(succeeded, "only way to get back a non-NULL result");
860 return result;
861 }
862
863 if (succeeded) {
864 // If we get here we successfully scheduled a collection which
865 // failed to allocate. No point in trying to allocate
866 // further. We'll just return NULL.
867 MutexLockerEx x(Heap_lock);
868 *gc_count_before_ret = total_collections();
869 return NULL;
870 }
871 } else {
872 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 // The GCLocker is either active or the GCLocker initiated
878 // GC has not yet been performed. Stall until it is and
879 // then retry the allocation.
880 GC_locker::stall_until_clear();
881 (*gclocker_retry_count_ret) += 1;
882 }
883
884 // We can reach here if we were unsuccessful in scheduling a
885 // collection (because another thread beat us to it) or if we were
886 // stalled due to the GC locker. In either can we should retry the
887 // allocation attempt in case another thread successfully
888 // performed a collection and reclaimed enough space. We do the
889 // first attempt (without holding the Heap_lock) here and the
890 // follow-on attempt will be at the start of the next loop
891 // iteration (after taking the Heap_lock).
892 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
893 false /* bot_updates */);
894 if (result != NULL) {
895 return result;
896 }
897
898 // Give a warning if we seem to be looping forever.
899 if ((QueuedAllocationWarningCount > 0) &&
900 (try_count % QueuedAllocationWarningCount == 0)) {
901 warning("G1CollectedHeap::attempt_allocation_slow() "
902 "retries %d times", try_count);
903 }
904 }
905
906 ShouldNotReachHere();
907 return NULL;
908 }
909
910 void G1CollectedHeap::begin_archive_alloc_range() {
911 assert_at_safepoint(true /* should_be_vm_thread */);
912 if (_archive_allocator == NULL) {
913 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
914 }
915 }
916
917 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
918 // Check whether the size would be considered humongous for a minimum-sized region.
919 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
920 }
921
922 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
923 assert_at_safepoint(true /* should_be_vm_thread */);
924 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
925
926 // Return NULL if the size would be considered humongous for a minimum-sized region.
927 // Otherwise, attempt to perform the allocation in the archive space.
928 if (is_archive_alloc_too_large(word_size)) {
929 return NULL;
930 }
931 return _archive_allocator->archive_mem_allocate(word_size);
932 }
933
934 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
935 uint end_alignment) {
936 assert_at_safepoint(true /* should_be_vm_thread */);
937 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
938
939 // Call complete_archive to do the real work, filling in the MemRegion
940 // array with the archive regions.
941 _archive_allocator->complete_archive(ranges, end_alignment);
942 _archive_allocator->~G1ArchiveAllocator();
943 _archive_allocator = NULL;
944 }
945
946 void G1CollectedHeap::fill_with_non_humongous_objects(HeapWord* base_address, size_t word_size) {
947 // Create filler objects for the specified range, being careful not to
948 // create any humongous objects.
949 if (!is_humongous(word_size)) {
950 CollectedHeap::fill_with_object(base_address, word_size);
951 } else {
952 size_t remainder = word_size;
953 size_t increment = humongous_threshold_for(HeapRegion::GrainWords) / 2;
954 HeapWord* fill_top = base_address;
955 // Don't let remainder get smaller than the minimum filler object size.
956 while ((remainder > increment) && (remainder - increment >= min_fill_size())) {
957 CollectedHeap::fill_with_object(fill_top, increment);
958 fill_top += increment;
959 remainder -= increment;
960 }
961 if (remainder != 0) {
962 CollectedHeap::fill_with_object(fill_top, remainder);
963 }
964 }
965 }
966
967 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, uint count) {
968 MemRegion mr = _hrm.reserved();
969 for (uint i = 0; i < count; i++) {
970 if (!mr.contains(ranges[i].start()) || !mr.contains(ranges[i].last())) {
971 return false;
972 }
973 }
974 return true;
975 }
976
977 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, uint count) {
978 MutexLockerEx x(Heap_lock);
979
980 MemRegion mr = _hrm.reserved();
981 HeapWord* prev_end_addr = NULL;
982 uint prev_end_index = 0;
983
984 // Temporarily disable pretouching of heap pages. This interface is used
985 // when mmap'ing archived heap data in, so pre-touching is wasted.
986 FlagSetting fs(AlwaysPreTouch, false);
987
988 // Enable archive object checking in G1MarkSweep. We have to let it know
989 // about each archive range, so that objects in those ranges aren't marked.
990 G1MarkSweep::enable_archive_object_check();
991
992 // For each specified MemRegion range, allocate the corresponding G1
993 // regions and mark them as archive regions.
994 // We expect the ranges in ascending order, without overlap.
995 for (uint i = 0; i < count; i++) {
996 HeapWord* base_address = ranges[i].start();
997 size_t word_size = ranges[i].word_size();
998 HeapWord* end_address = ranges[i].last();
999
1000 assert((base_address > prev_end_addr) && (base_address < end_address),
1001 "invalid range specification");
1002
1003 prev_end_addr = end_address;
1004 uint start_index = _hrm.addr_to_index(base_address);
1005 uint end_index = _hrm.addr_to_index(end_address);
1006
1007 // Check for ranges that begin/end in the same G1 region
1008 // as as the previous range.
1009 if (start_index == prev_end_index) {
1010 if (end_index == prev_end_index) {
1011 break;
1012 }
1013 start_index++;
1014 }
1015 prev_end_index = end_index;
1016
1017 // Ensure that each contained G1 region is available and free,
1018 // returning false if not.
1019 for (uint curr_index = start_index; curr_index <= end_index; curr_index++) {
1020 HeapRegion* curr_region;
1021 if ((curr_region = _hrm.at_or_null(curr_index)) == NULL) {
1022 ergo_verbose1(ErgoHeapSizing,
1023 "attempt heap expansion",
1024 ergo_format_reason("pinning region")
1025 ergo_format_byte("region size"),
1026 HeapRegion::GrainWords * HeapWordSize);
1027 _hrm.expand_at(curr_index, 1);
1028 } else {
1029 if (!curr_region->is_free()) {
1030 return false;
1031 }
1032 }
1033 }
1034
1035 _hrm.allocate_free_regions_starting_at(start_index, (end_index - start_index) + 1);
1036 _allocator->increase_used(word_size * HeapWordSize);
1037
1038 // Mark each G1 region touched by the range as archive, add it to the old set, and set
1039 // the allocation context and top.
1040 for (uint i = start_index; i <= end_index; i++) {
1041 HeapRegion* curr = region_at(i);
1042 assert(curr->is_empty() && !curr->is_pinned(), "Invalid MemRegion");
1043 _hr_printer.alloc(curr, G1HRPrinter::Archive);
1044 curr->set_allocation_context(AllocationContext::system());
1045 if (i != end_index) {
1046 curr->set_top(curr->end());
1047 } else {
1048 curr->set_top(end_address + 1);
1049 }
1050 curr->set_archive();
1051 _old_set.add(curr);
1052 }
1053
1054 // Notify mark-sweep of the archive range.
1055 G1MarkSweep::mark_range_archive(base_address, end_address);
1056 }
1057 return true;
1058 }
1059
1060 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, uint count) {
1061 MemRegion mr = _hrm.reserved();
1062 HeapWord *prev_end_addr = NULL;
1063 uint prev_end_index = 0;
1064
1065 // For each MemRegion, create filler objects, if needed, in the G1 regions
1066 // that contain the address range. The address range actually within the
1067 // MemRegion will not be modified. That is assumed to have been initialized
1068 // elsewhere, probably via an mmap of archived heap data.
1069 MutexLockerEx x(Heap_lock);
1070 for (uint i = 0; i < count; i++) {
1071 HeapWord* base_address = ranges[i].start();
1072 size_t word_size = ranges[i].word_size();
1073 HeapWord* end_address = ranges[i].last();
1074
1075 assert(mr.contains(base_address) && mr.contains(end_address),
1076 "MemRegion outside of heap");
1077
1078 uint start_index = _hrm.addr_to_index(base_address);
1079 uint end_index = _hrm.addr_to_index(end_address);
1080 HeapRegion* start_region = _hrm.addr_to_region(base_address);
1081 HeapRegion* end_region = _hrm.addr_to_region(end_address);
1082 HeapWord* bottom_address = start_region->bottom();
1083
1084 // Check for a range beginning in the same region in which the
1085 // previous one ended.
1086 if (start_index == prev_end_index) {
1087 bottom_address = prev_end_addr;
1088 start_index++;
1089 }
1090
1091 #ifdef ASSERT
1092 // Verify the regions were all marked as archive regions by
1093 // alloc_fixed_ranges.
1094 for (uint i = start_index; i <= end_index; i++) {
1095 HeapRegion* curr = region_at(i);
1096 assert(curr->is_archive(), "Invalid range in fill_archive_regions");
1097 }
1098 #endif
1099
1100 prev_end_addr = base_address + word_size;
1101 prev_end_index = end_index;
1102
1103 // Fill the low part of the first allocated region with dummy object(s),
1104 // if the region base does not match the range address, or if the previous
1105 // range ended within the same G1 region, and there is a gap.
1106 if (base_address != bottom_address) {
1107 size_t fill_size = base_address - bottom_address;
1108 G1CollectedHeap::fill_with_non_humongous_objects(bottom_address, fill_size);
1109 _allocator->increase_used(fill_size * HeapWordSize);
1110 }
1111 }
1112 }
1113
1114
1115 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1116 uint* gc_count_before_ret,
1117 uint* gclocker_retry_count_ret) {
1118 // The structure of this method has a lot of similarities to
1119 // attempt_allocation_slow(). The reason these two were not merged
1120 // into a single one is that such a method would require several "if
1121 // allocation is not humongous do this, otherwise do that"
1122 // conditional paths which would obscure its flow. In fact, an early
1123 // version of this code did use a unified method which was harder to
1124 // follow and, as a result, it had subtle bugs that were hard to
1125 // track down. So keeping these two methods separate allows each to
1126 // be more readable. It will be good to keep these two in sync as
1127 // much as possible.
1128
1129 assert_heap_not_locked_and_not_at_safepoint();
1130 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1131 "should only be called for humongous allocations");
1132
1133 // Humongous objects can exhaust the heap quickly, so we should check if we
1134 // need to start a marking cycle at each humongous object allocation. We do
1135 // the check before we do the actual allocation. The reason for doing it
1136 // before the allocation is that we avoid having to keep track of the newly
1137 // allocated memory while we do a GC.
1138 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1139 word_size)) {
1140 collect(GCCause::_g1_humongous_allocation);
1141 }
1142
1143 // We will loop until a) we manage to successfully perform the
1144 // allocation or b) we successfully schedule a collection which
1145 // fails to perform the allocation. b) is the only case when we'll
1146 // return NULL.
1147 HeapWord* result = NULL;
1148 for (int try_count = 1; /* we'll return */; try_count += 1) {
1149 bool should_try_gc;
1150 uint gc_count_before;
1151
1152 {
1153 MutexLockerEx x(Heap_lock);
1154
1155 // Given that humongous objects are not allocated in young
1156 // regions, we'll first try to do the allocation without doing a
1157 // collection hoping that there's enough space in the heap.
1158 result = humongous_obj_allocate(word_size, AllocationContext::current());
1159 if (result != NULL) {
1160 return result;
1161 }
1162
1163 if (GC_locker::is_active_and_needs_gc()) {
1164 should_try_gc = false;
1165 } else {
1166 // The GCLocker may not be active but the GCLocker initiated
1167 // GC may not yet have been performed (GCLocker::needs_gc()
1168 // returns true). In this case we do not try this GC and
1169 // wait until the GCLocker initiated GC is performed, and
1170 // then retry the allocation.
1171 if (GC_locker::needs_gc()) {
1172 should_try_gc = false;
1173 } else {
1174 // Read the GC count while still holding the Heap_lock.
1175 gc_count_before = total_collections();
1176 should_try_gc = true;
1177 }
1178 }
1179 }
1180
1181 if (should_try_gc) {
1182 // If we failed to allocate the humongous object, we should try to
1183 // do a collection pause (if we're allowed) in case it reclaims
1184 // enough space for the allocation to succeed after the pause.
1185
1186 bool succeeded;
1187 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1188 GCCause::_g1_humongous_allocation);
1189 if (result != NULL) {
1190 assert(succeeded, "only way to get back a non-NULL result");
1191 return result;
1192 }
1193
1194 if (succeeded) {
1195 // If we get here we successfully scheduled a collection which
1196 // failed to allocate. No point in trying to allocate
1197 // further. We'll just return NULL.
1198 MutexLockerEx x(Heap_lock);
1199 *gc_count_before_ret = total_collections();
1200 return NULL;
1201 }
1202 } else {
1203 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1204 MutexLockerEx x(Heap_lock);
1205 *gc_count_before_ret = total_collections();
1206 return NULL;
1207 }
1208 // The GCLocker is either active or the GCLocker initiated
1209 // GC has not yet been performed. Stall until it is and
1210 // then retry the allocation.
1211 GC_locker::stall_until_clear();
1212 (*gclocker_retry_count_ret) += 1;
1213 }
1214
1215 // We can reach here if we were unsuccessful in scheduling a
1216 // collection (because another thread beat us to it) or if we were
1217 // stalled due to the GC locker. In either can we should retry the
1218 // allocation attempt in case another thread successfully
1219 // performed a collection and reclaimed enough space. Give a
1220 // warning if we seem to be looping forever.
1221
1222 if ((QueuedAllocationWarningCount > 0) &&
1223 (try_count % QueuedAllocationWarningCount == 0)) {
1224 warning("G1CollectedHeap::attempt_allocation_humongous() "
1225 "retries %d times", try_count);
1226 }
1227 }
1228
1229 ShouldNotReachHere();
1230 return NULL;
1231 }
1232
1233 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1234 AllocationContext_t context,
1235 bool expect_null_mutator_alloc_region) {
1236 assert_at_safepoint(true /* should_be_vm_thread */);
1237 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1238 !expect_null_mutator_alloc_region,
1239 "the current alloc region was unexpectedly found to be non-NULL");
1240
1241 if (!is_humongous(word_size)) {
1242 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1243 false /* bot_updates */);
1244 } else {
1245 HeapWord* result = humongous_obj_allocate(word_size, context);
1246 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1247 g1_policy()->set_initiate_conc_mark_if_possible();
1248 }
1249 return result;
1250 }
1251
1252 ShouldNotReachHere();
1253 }
1254
1255 class PostMCRemSetClearClosure: public HeapRegionClosure {
1256 G1CollectedHeap* _g1h;
1257 ModRefBarrierSet* _mr_bs;
1258 public:
1259 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1260 _g1h(g1h), _mr_bs(mr_bs) {}
1261
1262 bool doHeapRegion(HeapRegion* r) {
1263 HeapRegionRemSet* hrrs = r->rem_set();
1264
1265 if (r->is_continues_humongous()) {
1266 // We'll assert that the strong code root list and RSet is empty
1267 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1268 assert(hrrs->occupied() == 0, "RSet should be empty");
1269 return false;
1270 }
1271
1272 _g1h->reset_gc_time_stamps(r);
1273 hrrs->clear();
1274 // You might think here that we could clear just the cards
1275 // corresponding to the used region. But no: if we leave a dirty card
1276 // in a region we might allocate into, then it would prevent that card
1277 // from being enqueued, and cause it to be missed.
1278 // Re: the performance cost: we shouldn't be doing full GC anyway!
1279 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1280
1281 return false;
1282 }
1283 };
1284
1285 void G1CollectedHeap::clear_rsets_post_compaction() {
1286 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1287 heap_region_iterate(&rs_clear);
1288 }
1289
1290 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1291 G1CollectedHeap* _g1h;
1292 UpdateRSOopClosure _cl;
1293 public:
1294 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1295 _cl(g1->g1_rem_set(), worker_i),
1296 _g1h(g1)
1297 { }
1298
1299 bool doHeapRegion(HeapRegion* r) {
1300 if (!r->is_continues_humongous()) {
1301 _cl.set_from(r);
1302 r->oop_iterate(&_cl);
1303 }
1304 return false;
1305 }
1306 };
1307
1308 class ParRebuildRSTask: public AbstractGangTask {
1309 G1CollectedHeap* _g1;
1310 HeapRegionClaimer _hrclaimer;
1311
1312 public:
1313 ParRebuildRSTask(G1CollectedHeap* g1) :
1314 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1315
1316 void work(uint worker_id) {
1317 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1318 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1319 }
1320 };
1321
1322 class PostCompactionPrinterClosure: public HeapRegionClosure {
1323 private:
1324 G1HRPrinter* _hr_printer;
1325 public:
1326 bool doHeapRegion(HeapRegion* hr) {
1327 assert(!hr->is_young(), "not expecting to find young regions");
1328 if (hr->is_free()) {
1329 // We only generate output for non-empty regions.
1330 } else if (hr->is_starts_humongous()) {
1331 if (hr->region_num() == 1) {
1332 // single humongous region
1333 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1334 } else {
1335 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1336 }
1337 } else if (hr->is_continues_humongous()) {
1338 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1339 } else if (hr->is_archive()) {
1340 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1341 } else if (hr->is_old()) {
1342 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1343 } else {
1344 ShouldNotReachHere();
1345 }
1346 return false;
1347 }
1348
1349 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1350 : _hr_printer(hr_printer) { }
1351 };
1352
1353 void G1CollectedHeap::print_hrm_post_compaction() {
1354 PostCompactionPrinterClosure cl(hr_printer());
1355 heap_region_iterate(&cl);
1356 }
1357
1358 bool G1CollectedHeap::do_collection(bool explicit_gc,
1359 bool clear_all_soft_refs,
1360 size_t word_size) {
1361 assert_at_safepoint(true /* should_be_vm_thread */);
1362
1363 if (GC_locker::check_active_before_gc()) {
1364 return false;
1365 }
1366
1367 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1368 gc_timer->register_gc_start();
1369
1370 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1371 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1372
1373 SvcGCMarker sgcm(SvcGCMarker::FULL);
1374 ResourceMark rm;
1375
1376 G1Log::update_level();
1377 print_heap_before_gc();
1378 trace_heap_before_gc(gc_tracer);
1379
1380 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1381
1382 verify_region_sets_optional();
1383
1384 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1385 collector_policy()->should_clear_all_soft_refs();
1386
1387 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1388
1389 {
1390 IsGCActiveMark x;
1391
1392 // Timing
1393 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1394 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1395
1396 {
1397 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1398 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1399 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1400
1401 g1_policy()->record_full_collection_start();
1402
1403 // Note: When we have a more flexible GC logging framework that
1404 // allows us to add optional attributes to a GC log record we
1405 // could consider timing and reporting how long we wait in the
1406 // following two methods.
1407 wait_while_free_regions_coming();
1408 // If we start the compaction before the CM threads finish
1409 // scanning the root regions we might trip them over as we'll
1410 // be moving objects / updating references. So let's wait until
1411 // they are done. By telling them to abort, they should complete
1412 // early.
1413 _cm->root_regions()->abort();
1414 _cm->root_regions()->wait_until_scan_finished();
1415 append_secondary_free_list_if_not_empty_with_lock();
1416
1417 gc_prologue(true);
1418 increment_total_collections(true /* full gc */);
1419 increment_old_marking_cycles_started();
1420
1421 assert(used() == recalculate_used(), "Should be equal");
1422
1423 verify_before_gc();
1424
1425 check_bitmaps("Full GC Start");
1426 pre_full_gc_dump(gc_timer);
1427
1428 COMPILER2_PRESENT(DerivedPointerTable::clear());
1429
1430 // Disable discovery and empty the discovered lists
1431 // for the CM ref processor.
1432 ref_processor_cm()->disable_discovery();
1433 ref_processor_cm()->abandon_partial_discovery();
1434 ref_processor_cm()->verify_no_references_recorded();
1435
1436 // Abandon current iterations of concurrent marking and concurrent
1437 // refinement, if any are in progress. We have to do this before
1438 // wait_until_scan_finished() below.
1439 concurrent_mark()->abort();
1440
1441 // Make sure we'll choose a new allocation region afterwards.
1442 _allocator->release_mutator_alloc_region();
1443 _allocator->abandon_gc_alloc_regions();
1444 g1_rem_set()->cleanupHRRS();
1445
1446 // We should call this after we retire any currently active alloc
1447 // regions so that all the ALLOC / RETIRE events are generated
1448 // before the start GC event.
1449 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1450
1451 // We may have added regions to the current incremental collection
1452 // set between the last GC or pause and now. We need to clear the
1453 // incremental collection set and then start rebuilding it afresh
1454 // after this full GC.
1455 abandon_collection_set(g1_policy()->inc_cset_head());
1456 g1_policy()->clear_incremental_cset();
1457 g1_policy()->stop_incremental_cset_building();
1458
1459 tear_down_region_sets(false /* free_list_only */);
1460 g1_policy()->set_gcs_are_young(true);
1461
1462 // See the comments in g1CollectedHeap.hpp and
1463 // G1CollectedHeap::ref_processing_init() about
1464 // how reference processing currently works in G1.
1465
1466 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1467 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1468
1469 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1470 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1471
1472 ref_processor_stw()->enable_discovery();
1473 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1474
1475 // Do collection work
1476 {
1477 HandleMark hm; // Discard invalid handles created during gc
1478 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1479 }
1480
1481 assert(num_free_regions() == 0, "we should not have added any free regions");
1482 rebuild_region_sets(false /* free_list_only */);
1483
1484 // Enqueue any discovered reference objects that have
1485 // not been removed from the discovered lists.
1486 ref_processor_stw()->enqueue_discovered_references();
1487
1488 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1489
1490 MemoryService::track_memory_usage();
1491
1492 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1493 ref_processor_stw()->verify_no_references_recorded();
1494
1495 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1496 ClassLoaderDataGraph::purge();
1497 MetaspaceAux::verify_metrics();
1498
1499 // Note: since we've just done a full GC, concurrent
1500 // marking is no longer active. Therefore we need not
1501 // re-enable reference discovery for the CM ref processor.
1502 // That will be done at the start of the next marking cycle.
1503 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1504 ref_processor_cm()->verify_no_references_recorded();
1505
1506 reset_gc_time_stamp();
1507 // Since everything potentially moved, we will clear all remembered
1508 // sets, and clear all cards. Later we will rebuild remembered
1509 // sets. We will also reset the GC time stamps of the regions.
1510 clear_rsets_post_compaction();
1511 check_gc_time_stamps();
1512
1513 // Resize the heap if necessary.
1514 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1515
1516 if (_hr_printer.is_active()) {
1517 // We should do this after we potentially resize the heap so
1518 // that all the COMMIT / UNCOMMIT events are generated before
1519 // the end GC event.
1520
1521 print_hrm_post_compaction();
1522 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1523 }
1524
1525 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1526 if (hot_card_cache->use_cache()) {
1527 hot_card_cache->reset_card_counts();
1528 hot_card_cache->reset_hot_cache();
1529 }
1530
1531 // Rebuild remembered sets of all regions.
1532 uint n_workers =
1533 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1534 workers()->active_workers(),
1535 Threads::number_of_non_daemon_threads());
1536 workers()->set_active_workers(n_workers);
1537
1538 ParRebuildRSTask rebuild_rs_task(this);
1539 workers()->run_task(&rebuild_rs_task);
1540
1541 // Rebuild the strong code root lists for each region
1542 rebuild_strong_code_roots();
1543
1544 if (true) { // FIXME
1545 MetaspaceGC::compute_new_size();
1546 }
1547
1548 #ifdef TRACESPINNING
1549 ParallelTaskTerminator::print_termination_counts();
1550 #endif
1551
1552 // Discard all rset updates
1553 JavaThread::dirty_card_queue_set().abandon_logs();
1554 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1555
1556 _young_list->reset_sampled_info();
1557 // At this point there should be no regions in the
1558 // entire heap tagged as young.
1559 assert(check_young_list_empty(true /* check_heap */),
1560 "young list should be empty at this point");
1561
1562 // Update the number of full collections that have been completed.
1563 increment_old_marking_cycles_completed(false /* concurrent */);
1564
1565 _hrm.verify_optional();
1566 verify_region_sets_optional();
1567
1568 verify_after_gc();
1569
1570 // Clear the previous marking bitmap, if needed for bitmap verification.
1571 // Note we cannot do this when we clear the next marking bitmap in
1572 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1573 // objects marked during a full GC against the previous bitmap.
1574 // But we need to clear it before calling check_bitmaps below since
1575 // the full GC has compacted objects and updated TAMS but not updated
1576 // the prev bitmap.
1577 if (G1VerifyBitmaps) {
1578 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1579 }
1580 check_bitmaps("Full GC End");
1581
1582 // Start a new incremental collection set for the next pause
1583 assert(g1_policy()->collection_set() == NULL, "must be");
1584 g1_policy()->start_incremental_cset_building();
1585
1586 clear_cset_fast_test();
1587
1588 _allocator->init_mutator_alloc_region();
1589
1590 g1_policy()->record_full_collection_end();
1591
1592 if (G1Log::fine()) {
1593 g1_policy()->print_heap_transition();
1594 }
1595
1596 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1597 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1598 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1599 // before any GC notifications are raised.
1600 g1mm()->update_sizes();
1601
1602 gc_epilogue(true);
1603 }
1604
1605 if (G1Log::finer()) {
1606 g1_policy()->print_detailed_heap_transition(true /* full */);
1607 }
1608
1609 print_heap_after_gc();
1610 trace_heap_after_gc(gc_tracer);
1611
1612 post_full_gc_dump(gc_timer);
1613
1614 gc_timer->register_gc_end();
1615 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1616 }
1617
1618 return true;
1619 }
1620
1621 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1622 // do_collection() will return whether it succeeded in performing
1623 // the GC. Currently, there is no facility on the
1624 // do_full_collection() API to notify the caller than the collection
1625 // did not succeed (e.g., because it was locked out by the GC
1626 // locker). So, right now, we'll ignore the return value.
1627 bool dummy = do_collection(true, /* explicit_gc */
1628 clear_all_soft_refs,
1629 0 /* word_size */);
1630 }
1631
1632 // This code is mostly copied from TenuredGeneration.
1633 void
1634 G1CollectedHeap::
1635 resize_if_necessary_after_full_collection(size_t word_size) {
1636 // Include the current allocation, if any, and bytes that will be
1637 // pre-allocated to support collections, as "used".
1638 const size_t used_after_gc = used();
1639 const size_t capacity_after_gc = capacity();
1640 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1641
1642 // This is enforced in arguments.cpp.
1643 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1644 "otherwise the code below doesn't make sense");
1645
1646 // We don't have floating point command-line arguments
1647 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1648 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1649 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1650 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1651
1652 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1653 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1654
1655 // We have to be careful here as these two calculations can overflow
1656 // 32-bit size_t's.
1657 double used_after_gc_d = (double) used_after_gc;
1658 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1659 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1660
1661 // Let's make sure that they are both under the max heap size, which
1662 // by default will make them fit into a size_t.
1663 double desired_capacity_upper_bound = (double) max_heap_size;
1664 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1665 desired_capacity_upper_bound);
1666 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1667 desired_capacity_upper_bound);
1668
1669 // We can now safely turn them into size_t's.
1670 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1671 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1672
1673 // This assert only makes sense here, before we adjust them
1674 // with respect to the min and max heap size.
1675 assert(minimum_desired_capacity <= maximum_desired_capacity,
1676 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1677 "maximum_desired_capacity = "SIZE_FORMAT,
1678 minimum_desired_capacity, maximum_desired_capacity));
1679
1680 // Should not be greater than the heap max size. No need to adjust
1681 // it with respect to the heap min size as it's a lower bound (i.e.,
1682 // we'll try to make the capacity larger than it, not smaller).
1683 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1684 // Should not be less than the heap min size. No need to adjust it
1685 // with respect to the heap max size as it's an upper bound (i.e.,
1686 // we'll try to make the capacity smaller than it, not greater).
1687 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1688
1689 if (capacity_after_gc < minimum_desired_capacity) {
1690 // Don't expand unless it's significant
1691 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1692 ergo_verbose4(ErgoHeapSizing,
1693 "attempt heap expansion",
1694 ergo_format_reason("capacity lower than "
1695 "min desired capacity after Full GC")
1696 ergo_format_byte("capacity")
1697 ergo_format_byte("occupancy")
1698 ergo_format_byte_perc("min desired capacity"),
1699 capacity_after_gc, used_after_gc,
1700 minimum_desired_capacity, (double) MinHeapFreeRatio);
1701 expand(expand_bytes);
1702
1703 // No expansion, now see if we want to shrink
1704 } else if (capacity_after_gc > maximum_desired_capacity) {
1705 // Capacity too large, compute shrinking size
1706 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1707 ergo_verbose4(ErgoHeapSizing,
1708 "attempt heap shrinking",
1709 ergo_format_reason("capacity higher than "
1710 "max desired capacity after Full GC")
1711 ergo_format_byte("capacity")
1712 ergo_format_byte("occupancy")
1713 ergo_format_byte_perc("max desired capacity"),
1714 capacity_after_gc, used_after_gc,
1715 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1716 shrink(shrink_bytes);
1717 }
1718 }
1719
1720
1721 HeapWord*
1722 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1723 AllocationContext_t context,
1724 bool* succeeded) {
1725 assert_at_safepoint(true /* should_be_vm_thread */);
1726
1727 *succeeded = true;
1728 // Let's attempt the allocation first.
1729 HeapWord* result =
1730 attempt_allocation_at_safepoint(word_size,
1731 context,
1732 false /* expect_null_mutator_alloc_region */);
1733 if (result != NULL) {
1734 assert(*succeeded, "sanity");
1735 return result;
1736 }
1737
1738 // In a G1 heap, we're supposed to keep allocation from failing by
1739 // incremental pauses. Therefore, at least for now, we'll favor
1740 // expansion over collection. (This might change in the future if we can
1741 // do something smarter than full collection to satisfy a failed alloc.)
1742 result = expand_and_allocate(word_size, context);
1743 if (result != NULL) {
1744 assert(*succeeded, "sanity");
1745 return result;
1746 }
1747
1748 // Expansion didn't work, we'll try to do a Full GC.
1749 bool gc_succeeded = do_collection(false, /* explicit_gc */
1750 false, /* clear_all_soft_refs */
1751 word_size);
1752 if (!gc_succeeded) {
1753 *succeeded = false;
1754 return NULL;
1755 }
1756
1757 // Retry the allocation
1758 result = attempt_allocation_at_safepoint(word_size,
1759 context,
1760 true /* expect_null_mutator_alloc_region */);
1761 if (result != NULL) {
1762 assert(*succeeded, "sanity");
1763 return result;
1764 }
1765
1766 // Then, try a Full GC that will collect all soft references.
1767 gc_succeeded = do_collection(false, /* explicit_gc */
1768 true, /* clear_all_soft_refs */
1769 word_size);
1770 if (!gc_succeeded) {
1771 *succeeded = false;
1772 return NULL;
1773 }
1774
1775 // Retry the allocation once more
1776 result = attempt_allocation_at_safepoint(word_size,
1777 context,
1778 true /* expect_null_mutator_alloc_region */);
1779 if (result != NULL) {
1780 assert(*succeeded, "sanity");
1781 return result;
1782 }
1783
1784 assert(!collector_policy()->should_clear_all_soft_refs(),
1785 "Flag should have been handled and cleared prior to this point");
1786
1787 // What else? We might try synchronous finalization later. If the total
1788 // space available is large enough for the allocation, then a more
1789 // complete compaction phase than we've tried so far might be
1790 // appropriate.
1791 assert(*succeeded, "sanity");
1792 return NULL;
1793 }
1794
1795 // Attempting to expand the heap sufficiently
1796 // to support an allocation of the given "word_size". If
1797 // successful, perform the allocation and return the address of the
1798 // allocated block, or else "NULL".
1799
1800 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1801 assert_at_safepoint(true /* should_be_vm_thread */);
1802
1803 verify_region_sets_optional();
1804
1805 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1806 ergo_verbose1(ErgoHeapSizing,
1807 "attempt heap expansion",
1808 ergo_format_reason("allocation request failed")
1809 ergo_format_byte("allocation request"),
1810 word_size * HeapWordSize);
1811 if (expand(expand_bytes)) {
1812 _hrm.verify_optional();
1813 verify_region_sets_optional();
1814 return attempt_allocation_at_safepoint(word_size,
1815 context,
1816 false /* expect_null_mutator_alloc_region */);
1817 }
1818 return NULL;
1819 }
1820
1821 bool G1CollectedHeap::expand(size_t expand_bytes) {
1822 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1823 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1824 HeapRegion::GrainBytes);
1825 ergo_verbose2(ErgoHeapSizing,
1826 "expand the heap",
1827 ergo_format_byte("requested expansion amount")
1828 ergo_format_byte("attempted expansion amount"),
1829 expand_bytes, aligned_expand_bytes);
1830
1831 if (is_maximal_no_gc()) {
1832 ergo_verbose0(ErgoHeapSizing,
1833 "did not expand the heap",
1834 ergo_format_reason("heap already fully expanded"));
1835 return false;
1836 }
1837
1838 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1839 assert(regions_to_expand > 0, "Must expand by at least one region");
1840
1841 uint expanded_by = _hrm.expand_by(regions_to_expand);
1842
1843 if (expanded_by > 0) {
1844 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1845 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1846 g1_policy()->record_new_heap_size(num_regions());
1847 } else {
1848 ergo_verbose0(ErgoHeapSizing,
1849 "did not expand the heap",
1850 ergo_format_reason("heap expansion operation failed"));
1851 // The expansion of the virtual storage space was unsuccessful.
1852 // Let's see if it was because we ran out of swap.
1853 if (G1ExitOnExpansionFailure &&
1854 _hrm.available() >= regions_to_expand) {
1855 // We had head room...
1856 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1857 }
1858 }
1859 return regions_to_expand > 0;
1860 }
1861
1862 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1863 size_t aligned_shrink_bytes =
1864 ReservedSpace::page_align_size_down(shrink_bytes);
1865 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1866 HeapRegion::GrainBytes);
1867 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1868
1869 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1870 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1871
1872 ergo_verbose3(ErgoHeapSizing,
1873 "shrink the heap",
1874 ergo_format_byte("requested shrinking amount")
1875 ergo_format_byte("aligned shrinking amount")
1876 ergo_format_byte("attempted shrinking amount"),
1877 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1878 if (num_regions_removed > 0) {
1879 g1_policy()->record_new_heap_size(num_regions());
1880 } else {
1881 ergo_verbose0(ErgoHeapSizing,
1882 "did not shrink the heap",
1883 ergo_format_reason("heap shrinking operation failed"));
1884 }
1885 }
1886
1887 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1888 verify_region_sets_optional();
1889
1890 // We should only reach here at the end of a Full GC which means we
1891 // should not not be holding to any GC alloc regions. The method
1892 // below will make sure of that and do any remaining clean up.
1893 _allocator->abandon_gc_alloc_regions();
1894
1895 // Instead of tearing down / rebuilding the free lists here, we
1896 // could instead use the remove_all_pending() method on free_list to
1897 // remove only the ones that we need to remove.
1898 tear_down_region_sets(true /* free_list_only */);
1899 shrink_helper(shrink_bytes);
1900 rebuild_region_sets(true /* free_list_only */);
1901
1902 _hrm.verify_optional();
1903 verify_region_sets_optional();
1904 }
1905
1906 // Public methods.
1907
1908 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1909 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1910 #endif // _MSC_VER
1911
1912
1913 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1914 CollectedHeap(),
1915 _g1_policy(policy_),
1916 _dirty_card_queue_set(false),
1917 _into_cset_dirty_card_queue_set(false),
1918 _is_alive_closure_cm(this),
1919 _is_alive_closure_stw(this),
1920 _ref_processor_cm(NULL),
1921 _ref_processor_stw(NULL),
1922 _bot_shared(NULL),
1923 _evac_failure_scan_stack(NULL),
1924 _mark_in_progress(false),
1925 _cg1r(NULL),
1926 _g1mm(NULL),
1927 _refine_cte_cl(NULL),
1928 _full_collection(false),
1929 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1930 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1931 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1932 _humongous_reclaim_candidates(),
1933 _has_humongous_reclaim_candidates(false),
1934 _archive_allocator(NULL),
1935 _free_regions_coming(false),
1936 _young_list(new YoungList(this)),
1937 _gc_time_stamp(0),
1938 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1939 _old_plab_stats(OldPLABSize, PLABWeight),
1940 _expand_heap_after_alloc_failure(true),
1941 _surviving_young_words(NULL),
1942 _old_marking_cycles_started(0),
1943 _old_marking_cycles_completed(0),
1944 _concurrent_cycle_started(false),
1945 _heap_summary_sent(false),
1946 _in_cset_fast_test(),
1947 _dirty_cards_region_list(NULL),
1948 _worker_cset_start_region(NULL),
1949 _worker_cset_start_region_time_stamp(NULL),
1950 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1951 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1952 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1953 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1954
1955 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1956 /* are_GC_task_threads */true,
1957 /* are_ConcurrentGC_threads */false);
1958 _workers->initialize_workers();
1959
1960 _allocator = G1Allocator::create_allocator(this);
1961 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1962
1963 int n_queues = (int)ParallelGCThreads;
1964 _task_queues = new RefToScanQueueSet(n_queues);
1965
1966 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1967 assert(n_rem_sets > 0, "Invariant.");
1968
1969 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1970 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1971 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1972
1973 for (int i = 0; i < n_queues; i++) {
1974 RefToScanQueue* q = new RefToScanQueue();
1975 q->initialize();
1976 _task_queues->register_queue(i, q);
1977 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1978 }
1979 clear_cset_start_regions();
1980
1981 // Initialize the G1EvacuationFailureALot counters and flags.
1982 NOT_PRODUCT(reset_evacuation_should_fail();)
1983
1984 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1985 }
1986
1987 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1988 size_t size,
1989 size_t translation_factor) {
1990 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1991 // Allocate a new reserved space, preferring to use large pages.
1992 ReservedSpace rs(size, preferred_page_size);
1993 G1RegionToSpaceMapper* result =
1994 G1RegionToSpaceMapper::create_mapper(rs,
1995 size,
1996 rs.alignment(),
1997 HeapRegion::GrainBytes,
1998 translation_factor,
1999 mtGC);
2000 if (TracePageSizes) {
2001 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2002 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2003 }
2004 return result;
2005 }
2006
2007 jint G1CollectedHeap::initialize() {
2008 CollectedHeap::pre_initialize();
2009 os::enable_vtime();
2010
2011 G1Log::init();
2012
2013 // Necessary to satisfy locking discipline assertions.
2014
2015 MutexLocker x(Heap_lock);
2016
2017 // We have to initialize the printer before committing the heap, as
2018 // it will be used then.
2019 _hr_printer.set_active(G1PrintHeapRegions);
2020
2021 // While there are no constraints in the GC code that HeapWordSize
2022 // be any particular value, there are multiple other areas in the
2023 // system which believe this to be true (e.g. oop->object_size in some
2024 // cases incorrectly returns the size in wordSize units rather than
2025 // HeapWordSize).
2026 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2027
2028 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2029 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2030 size_t heap_alignment = collector_policy()->heap_alignment();
2031
2032 // Ensure that the sizes are properly aligned.
2033 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2034 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2035 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2036
2037 _refine_cte_cl = new RefineCardTableEntryClosure();
2038
2039 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2040
2041 // Reserve the maximum.
2042
2043 // When compressed oops are enabled, the preferred heap base
2044 // is calculated by subtracting the requested size from the
2045 // 32Gb boundary and using the result as the base address for
2046 // heap reservation. If the requested size is not aligned to
2047 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2048 // into the ReservedHeapSpace constructor) then the actual
2049 // base of the reserved heap may end up differing from the
2050 // address that was requested (i.e. the preferred heap base).
2051 // If this happens then we could end up using a non-optimal
2052 // compressed oops mode.
2053
2054 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2055 heap_alignment);
2056
2057 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2058
2059 // Create the barrier set for the entire reserved region.
2060 G1SATBCardTableLoggingModRefBS* bs
2061 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2062 bs->initialize();
2063 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2064 set_barrier_set(bs);
2065
2066 // Also create a G1 rem set.
2067 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2068
2069 // Carve out the G1 part of the heap.
2070
2071 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2072 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2073 G1RegionToSpaceMapper* heap_storage =
2074 G1RegionToSpaceMapper::create_mapper(g1_rs,
2075 g1_rs.size(),
2076 page_size,
2077 HeapRegion::GrainBytes,
2078 1,
2079 mtJavaHeap);
2080 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2081 max_byte_size, page_size,
2082 heap_rs.base(),
2083 heap_rs.size());
2084 heap_storage->set_mapping_changed_listener(&_listener);
2085
2086 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2087 G1RegionToSpaceMapper* bot_storage =
2088 create_aux_memory_mapper("Block offset table",
2089 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2090 G1BlockOffsetSharedArray::heap_map_factor());
2091
2092 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2093 G1RegionToSpaceMapper* cardtable_storage =
2094 create_aux_memory_mapper("Card table",
2095 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2096 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2097
2098 G1RegionToSpaceMapper* card_counts_storage =
2099 create_aux_memory_mapper("Card counts table",
2100 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2101 G1CardCounts::heap_map_factor());
2102
2103 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2104 G1RegionToSpaceMapper* prev_bitmap_storage =
2105 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2106 G1RegionToSpaceMapper* next_bitmap_storage =
2107 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2108
2109 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2110 g1_barrier_set()->initialize(cardtable_storage);
2111 // Do later initialization work for concurrent refinement.
2112 _cg1r->init(card_counts_storage);
2113
2114 // 6843694 - ensure that the maximum region index can fit
2115 // in the remembered set structures.
2116 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2117 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2118
2119 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2120 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2121 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2122 "too many cards per region");
2123
2124 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2125
2126 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2127
2128 {
2129 HeapWord* start = _hrm.reserved().start();
2130 HeapWord* end = _hrm.reserved().end();
2131 size_t granularity = HeapRegion::GrainBytes;
2132
2133 _in_cset_fast_test.initialize(start, end, granularity);
2134 _humongous_reclaim_candidates.initialize(start, end, granularity);
2135 }
2136
2137 // Create the ConcurrentMark data structure and thread.
2138 // (Must do this late, so that "max_regions" is defined.)
2139 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2140 if (_cm == NULL || !_cm->completed_initialization()) {
2141 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2142 return JNI_ENOMEM;
2143 }
2144 _cmThread = _cm->cmThread();
2145
2146 // Initialize the from_card cache structure of HeapRegionRemSet.
2147 HeapRegionRemSet::init_heap(max_regions());
2148
2149 // Now expand into the initial heap size.
2150 if (!expand(init_byte_size)) {
2151 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2152 return JNI_ENOMEM;
2153 }
2154
2155 // Perform any initialization actions delegated to the policy.
2156 g1_policy()->init();
2157
2158 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2159 SATB_Q_FL_lock,
2160 G1SATBProcessCompletedThreshold,
2161 Shared_SATB_Q_lock);
2162
2163 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2164 DirtyCardQ_CBL_mon,
2165 DirtyCardQ_FL_lock,
2166 concurrent_g1_refine()->yellow_zone(),
2167 concurrent_g1_refine()->red_zone(),
2168 Shared_DirtyCardQ_lock);
2169
2170 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2171 DirtyCardQ_CBL_mon,
2172 DirtyCardQ_FL_lock,
2173 -1, // never trigger processing
2174 -1, // no limit on length
2175 Shared_DirtyCardQ_lock,
2176 &JavaThread::dirty_card_queue_set());
2177
2178 // Initialize the card queue set used to hold cards containing
2179 // references into the collection set.
2180 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2181 DirtyCardQ_CBL_mon,
2182 DirtyCardQ_FL_lock,
2183 -1, // never trigger processing
2184 -1, // no limit on length
2185 Shared_DirtyCardQ_lock,
2186 &JavaThread::dirty_card_queue_set());
2187
2188 // Here we allocate the dummy HeapRegion that is required by the
2189 // G1AllocRegion class.
2190 HeapRegion* dummy_region = _hrm.get_dummy_region();
2191
2192 // We'll re-use the same region whether the alloc region will
2193 // require BOT updates or not and, if it doesn't, then a non-young
2194 // region will complain that it cannot support allocations without
2195 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2196 dummy_region->set_eden();
2197 // Make sure it's full.
2198 dummy_region->set_top(dummy_region->end());
2199 G1AllocRegion::setup(this, dummy_region);
2200
2201 _allocator->init_mutator_alloc_region();
2202
2203 // Do create of the monitoring and management support so that
2204 // values in the heap have been properly initialized.
2205 _g1mm = new G1MonitoringSupport(this);
2206
2207 G1StringDedup::initialize();
2208
2209 return JNI_OK;
2210 }
2211
2212 void G1CollectedHeap::stop() {
2213 // Stop all concurrent threads. We do this to make sure these threads
2214 // do not continue to execute and access resources (e.g. gclog_or_tty)
2215 // that are destroyed during shutdown.
2216 _cg1r->stop();
2217 _cmThread->stop();
2218 if (G1StringDedup::is_enabled()) {
2219 G1StringDedup::stop();
2220 }
2221 }
2222
2223 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2224 return HeapRegion::max_region_size();
2225 }
2226
2227 void G1CollectedHeap::post_initialize() {
2228 CollectedHeap::post_initialize();
2229 ref_processing_init();
2230 }
2231
2232 void G1CollectedHeap::ref_processing_init() {
2233 // Reference processing in G1 currently works as follows:
2234 //
2235 // * There are two reference processor instances. One is
2236 // used to record and process discovered references
2237 // during concurrent marking; the other is used to
2238 // record and process references during STW pauses
2239 // (both full and incremental).
2240 // * Both ref processors need to 'span' the entire heap as
2241 // the regions in the collection set may be dotted around.
2242 //
2243 // * For the concurrent marking ref processor:
2244 // * Reference discovery is enabled at initial marking.
2245 // * Reference discovery is disabled and the discovered
2246 // references processed etc during remarking.
2247 // * Reference discovery is MT (see below).
2248 // * Reference discovery requires a barrier (see below).
2249 // * Reference processing may or may not be MT
2250 // (depending on the value of ParallelRefProcEnabled
2251 // and ParallelGCThreads).
2252 // * A full GC disables reference discovery by the CM
2253 // ref processor and abandons any entries on it's
2254 // discovered lists.
2255 //
2256 // * For the STW processor:
2257 // * Non MT discovery is enabled at the start of a full GC.
2258 // * Processing and enqueueing during a full GC is non-MT.
2259 // * During a full GC, references are processed after marking.
2260 //
2261 // * Discovery (may or may not be MT) is enabled at the start
2262 // of an incremental evacuation pause.
2263 // * References are processed near the end of a STW evacuation pause.
2264 // * For both types of GC:
2265 // * Discovery is atomic - i.e. not concurrent.
2266 // * Reference discovery will not need a barrier.
2267
2268 MemRegion mr = reserved_region();
2269
2270 // Concurrent Mark ref processor
2271 _ref_processor_cm =
2272 new ReferenceProcessor(mr, // span
2273 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2274 // mt processing
2275 (uint) ParallelGCThreads,
2276 // degree of mt processing
2277 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2278 // mt discovery
2279 (uint) MAX2(ParallelGCThreads, ConcGCThreads),
2280 // degree of mt discovery
2281 false,
2282 // Reference discovery is not atomic
2283 &_is_alive_closure_cm);
2284 // is alive closure
2285 // (for efficiency/performance)
2286
2287 // STW ref processor
2288 _ref_processor_stw =
2289 new ReferenceProcessor(mr, // span
2290 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2291 // mt processing
2292 (uint) ParallelGCThreads,
2293 // degree of mt processing
2294 (ParallelGCThreads > 1),
2295 // mt discovery
2296 (uint) ParallelGCThreads,
2297 // degree of mt discovery
2298 true,
2299 // Reference discovery is atomic
2300 &_is_alive_closure_stw);
2301 // is alive closure
2302 // (for efficiency/performance)
2303 }
2304
2305 size_t G1CollectedHeap::capacity() const {
2306 return _hrm.length() * HeapRegion::GrainBytes;
2307 }
2308
2309 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2310 assert(!hr->is_continues_humongous(), "pre-condition");
2311 hr->reset_gc_time_stamp();
2312 if (hr->is_starts_humongous()) {
2313 uint first_index = hr->hrm_index() + 1;
2314 uint last_index = hr->last_hc_index();
2315 for (uint i = first_index; i < last_index; i += 1) {
2316 HeapRegion* chr = region_at(i);
2317 assert(chr->is_continues_humongous(), "sanity");
2318 chr->reset_gc_time_stamp();
2319 }
2320 }
2321 }
2322
2323 #ifndef PRODUCT
2324
2325 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2326 private:
2327 unsigned _gc_time_stamp;
2328 bool _failures;
2329
2330 public:
2331 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2332 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2333
2334 virtual bool doHeapRegion(HeapRegion* hr) {
2335 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2336 if (_gc_time_stamp != region_gc_time_stamp) {
2337 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2338 "expected %d", HR_FORMAT_PARAMS(hr),
2339 region_gc_time_stamp, _gc_time_stamp);
2340 _failures = true;
2341 }
2342 return false;
2343 }
2344
2345 bool failures() { return _failures; }
2346 };
2347
2348 void G1CollectedHeap::check_gc_time_stamps() {
2349 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2350 heap_region_iterate(&cl);
2351 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2352 }
2353 #endif // PRODUCT
2354
2355 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2356 DirtyCardQueue* into_cset_dcq,
2357 bool concurrent,
2358 uint worker_i) {
2359 // Clean cards in the hot card cache
2360 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2361 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2362
2363 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2364 size_t n_completed_buffers = 0;
2365 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2366 n_completed_buffers++;
2367 }
2368 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2369 dcqs.clear_n_completed_buffers();
2370 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2371 }
2372
2373
2374 // Computes the sum of the storage used by the various regions.
2375 size_t G1CollectedHeap::used() const {
2376 size_t result = _allocator->used();
2377 if (_archive_allocator != NULL) {
2378 result += _archive_allocator->used();
2379 }
2380 return result;
2381 }
2382
2383 size_t G1CollectedHeap::used_unlocked() const {
2384 return _allocator->used_unlocked();
2385 }
2386
2387 class SumUsedClosure: public HeapRegionClosure {
2388 size_t _used;
2389 public:
2390 SumUsedClosure() : _used(0) {}
2391 bool doHeapRegion(HeapRegion* r) {
2392 if (!r->is_continues_humongous()) {
2393 _used += r->used();
2394 }
2395 return false;
2396 }
2397 size_t result() { return _used; }
2398 };
2399
2400 size_t G1CollectedHeap::recalculate_used() const {
2401 double recalculate_used_start = os::elapsedTime();
2402
2403 SumUsedClosure blk;
2404 heap_region_iterate(&blk);
2405
2406 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2407 return blk.result();
2408 }
2409
2410 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2411 switch (cause) {
2412 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2413 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2414 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2415 case GCCause::_g1_humongous_allocation: return true;
2416 case GCCause::_update_allocation_context_stats_inc: return true;
2417 case GCCause::_wb_conc_mark: return true;
2418 default: return false;
2419 }
2420 }
2421
2422 #ifndef PRODUCT
2423 void G1CollectedHeap::allocate_dummy_regions() {
2424 // Let's fill up most of the region
2425 size_t word_size = HeapRegion::GrainWords - 1024;
2426 // And as a result the region we'll allocate will be humongous.
2427 guarantee(is_humongous(word_size), "sanity");
2428
2429 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2430 // Let's use the existing mechanism for the allocation
2431 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2432 AllocationContext::system());
2433 if (dummy_obj != NULL) {
2434 MemRegion mr(dummy_obj, word_size);
2435 CollectedHeap::fill_with_object(mr);
2436 } else {
2437 // If we can't allocate once, we probably cannot allocate
2438 // again. Let's get out of the loop.
2439 break;
2440 }
2441 }
2442 }
2443 #endif // !PRODUCT
2444
2445 void G1CollectedHeap::increment_old_marking_cycles_started() {
2446 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2447 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2448 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2449 _old_marking_cycles_started, _old_marking_cycles_completed));
2450
2451 _old_marking_cycles_started++;
2452 }
2453
2454 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2455 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2456
2457 // We assume that if concurrent == true, then the caller is a
2458 // concurrent thread that was joined the Suspendible Thread
2459 // Set. If there's ever a cheap way to check this, we should add an
2460 // assert here.
2461
2462 // Given that this method is called at the end of a Full GC or of a
2463 // concurrent cycle, and those can be nested (i.e., a Full GC can
2464 // interrupt a concurrent cycle), the number of full collections
2465 // completed should be either one (in the case where there was no
2466 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2467 // behind the number of full collections started.
2468
2469 // This is the case for the inner caller, i.e. a Full GC.
2470 assert(concurrent ||
2471 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2472 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2473 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2474 "is inconsistent with _old_marking_cycles_completed = %u",
2475 _old_marking_cycles_started, _old_marking_cycles_completed));
2476
2477 // This is the case for the outer caller, i.e. the concurrent cycle.
2478 assert(!concurrent ||
2479 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2480 err_msg("for outer caller (concurrent cycle): "
2481 "_old_marking_cycles_started = %u "
2482 "is inconsistent with _old_marking_cycles_completed = %u",
2483 _old_marking_cycles_started, _old_marking_cycles_completed));
2484
2485 _old_marking_cycles_completed += 1;
2486
2487 // We need to clear the "in_progress" flag in the CM thread before
2488 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2489 // is set) so that if a waiter requests another System.gc() it doesn't
2490 // incorrectly see that a marking cycle is still in progress.
2491 if (concurrent) {
2492 _cmThread->clear_in_progress();
2493 }
2494
2495 // This notify_all() will ensure that a thread that called
2496 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2497 // and it's waiting for a full GC to finish will be woken up. It is
2498 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2499 FullGCCount_lock->notify_all();
2500 }
2501
2502 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2503 _concurrent_cycle_started = true;
2504 _gc_timer_cm->register_gc_start(start_time);
2505
2506 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2507 trace_heap_before_gc(_gc_tracer_cm);
2508 }
2509
2510 void G1CollectedHeap::register_concurrent_cycle_end() {
2511 if (_concurrent_cycle_started) {
2512 if (_cm->has_aborted()) {
2513 _gc_tracer_cm->report_concurrent_mode_failure();
2514 }
2515
2516 _gc_timer_cm->register_gc_end();
2517 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2518
2519 // Clear state variables to prepare for the next concurrent cycle.
2520 _concurrent_cycle_started = false;
2521 _heap_summary_sent = false;
2522 }
2523 }
2524
2525 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2526 if (_concurrent_cycle_started) {
2527 // This function can be called when:
2528 // the cleanup pause is run
2529 // the concurrent cycle is aborted before the cleanup pause.
2530 // the concurrent cycle is aborted after the cleanup pause,
2531 // but before the concurrent cycle end has been registered.
2532 // Make sure that we only send the heap information once.
2533 if (!_heap_summary_sent) {
2534 trace_heap_after_gc(_gc_tracer_cm);
2535 _heap_summary_sent = true;
2536 }
2537 }
2538 }
2539
2540 G1YCType G1CollectedHeap::yc_type() {
2541 bool is_young = g1_policy()->gcs_are_young();
2542 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2543 bool is_during_mark = mark_in_progress();
2544
2545 if (is_initial_mark) {
2546 return InitialMark;
2547 } else if (is_during_mark) {
2548 return DuringMark;
2549 } else if (is_young) {
2550 return Normal;
2551 } else {
2552 return Mixed;
2553 }
2554 }
2555
2556 void G1CollectedHeap::collect(GCCause::Cause cause) {
2557 assert_heap_not_locked();
2558
2559 uint gc_count_before;
2560 uint old_marking_count_before;
2561 uint full_gc_count_before;
2562 bool retry_gc;
2563
2564 do {
2565 retry_gc = false;
2566
2567 {
2568 MutexLocker ml(Heap_lock);
2569
2570 // Read the GC count while holding the Heap_lock
2571 gc_count_before = total_collections();
2572 full_gc_count_before = total_full_collections();
2573 old_marking_count_before = _old_marking_cycles_started;
2574 }
2575
2576 if (should_do_concurrent_full_gc(cause)) {
2577 // Schedule an initial-mark evacuation pause that will start a
2578 // concurrent cycle. We're setting word_size to 0 which means that
2579 // we are not requesting a post-GC allocation.
2580 VM_G1IncCollectionPause op(gc_count_before,
2581 0, /* word_size */
2582 true, /* should_initiate_conc_mark */
2583 g1_policy()->max_pause_time_ms(),
2584 cause);
2585 op.set_allocation_context(AllocationContext::current());
2586
2587 VMThread::execute(&op);
2588 if (!op.pause_succeeded()) {
2589 if (old_marking_count_before == _old_marking_cycles_started) {
2590 retry_gc = op.should_retry_gc();
2591 } else {
2592 // A Full GC happened while we were trying to schedule the
2593 // initial-mark GC. No point in starting a new cycle given
2594 // that the whole heap was collected anyway.
2595 }
2596
2597 if (retry_gc) {
2598 if (GC_locker::is_active_and_needs_gc()) {
2599 GC_locker::stall_until_clear();
2600 }
2601 }
2602 }
2603 } else {
2604 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2605 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2606
2607 // Schedule a standard evacuation pause. We're setting word_size
2608 // to 0 which means that we are not requesting a post-GC allocation.
2609 VM_G1IncCollectionPause op(gc_count_before,
2610 0, /* word_size */
2611 false, /* should_initiate_conc_mark */
2612 g1_policy()->max_pause_time_ms(),
2613 cause);
2614 VMThread::execute(&op);
2615 } else {
2616 // Schedule a Full GC.
2617 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2618 VMThread::execute(&op);
2619 }
2620 }
2621 } while (retry_gc);
2622 }
2623
2624 bool G1CollectedHeap::is_in(const void* p) const {
2625 if (_hrm.reserved().contains(p)) {
2626 // Given that we know that p is in the reserved space,
2627 // heap_region_containing_raw() should successfully
2628 // return the containing region.
2629 HeapRegion* hr = heap_region_containing_raw(p);
2630 return hr->is_in(p);
2631 } else {
2632 return false;
2633 }
2634 }
2635
2636 #ifdef ASSERT
2637 bool G1CollectedHeap::is_in_exact(const void* p) const {
2638 bool contains = reserved_region().contains(p);
2639 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2640 if (contains && available) {
2641 return true;
2642 } else {
2643 return false;
2644 }
2645 }
2646 #endif
2647
2648 // Iteration functions.
2649
2650 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2651
2652 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2653 ExtendedOopClosure* _cl;
2654 public:
2655 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2656 bool doHeapRegion(HeapRegion* r) {
2657 if (!r->is_continues_humongous()) {
2658 r->oop_iterate(_cl);
2659 }
2660 return false;
2661 }
2662 };
2663
2664 // Iterates an ObjectClosure over all objects within a HeapRegion.
2665
2666 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2667 ObjectClosure* _cl;
2668 public:
2669 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2670 bool doHeapRegion(HeapRegion* r) {
2671 if (!r->is_continues_humongous()) {
2672 r->object_iterate(_cl);
2673 }
2674 return false;
2675 }
2676 };
2677
2678 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2679 IterateObjectClosureRegionClosure blk(cl);
2680 heap_region_iterate(&blk);
2681 }
2682
2683 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2684 _hrm.iterate(cl);
2685 }
2686
2687 void
2688 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2689 uint worker_id,
2690 HeapRegionClaimer *hrclaimer,
2691 bool concurrent) const {
2692 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2693 }
2694
2695 // Clear the cached CSet starting regions and (more importantly)
2696 // the time stamps. Called when we reset the GC time stamp.
2697 void G1CollectedHeap::clear_cset_start_regions() {
2698 assert(_worker_cset_start_region != NULL, "sanity");
2699 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2700
2701 for (uint i = 0; i < ParallelGCThreads; i++) {
2702 _worker_cset_start_region[i] = NULL;
2703 _worker_cset_start_region_time_stamp[i] = 0;
2704 }
2705 }
2706
2707 // Given the id of a worker, obtain or calculate a suitable
2708 // starting region for iterating over the current collection set.
2709 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2710 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2711
2712 HeapRegion* result = NULL;
2713 unsigned gc_time_stamp = get_gc_time_stamp();
2714
2715 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2716 // Cached starting region for current worker was set
2717 // during the current pause - so it's valid.
2718 // Note: the cached starting heap region may be NULL
2719 // (when the collection set is empty).
2720 result = _worker_cset_start_region[worker_i];
2721 assert(result == NULL || result->in_collection_set(), "sanity");
2722 return result;
2723 }
2724
2725 // The cached entry was not valid so let's calculate
2726 // a suitable starting heap region for this worker.
2727
2728 // We want the parallel threads to start their collection
2729 // set iteration at different collection set regions to
2730 // avoid contention.
2731 // If we have:
2732 // n collection set regions
2733 // p threads
2734 // Then thread t will start at region floor ((t * n) / p)
2735
2736 result = g1_policy()->collection_set();
2737 uint cs_size = g1_policy()->cset_region_length();
2738 uint active_workers = workers()->active_workers();
2739
2740 uint end_ind = (cs_size * worker_i) / active_workers;
2741 uint start_ind = 0;
2742
2743 if (worker_i > 0 &&
2744 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2745 // Previous workers starting region is valid
2746 // so let's iterate from there
2747 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2748 result = _worker_cset_start_region[worker_i - 1];
2749 }
2750
2751 for (uint i = start_ind; i < end_ind; i++) {
2752 result = result->next_in_collection_set();
2753 }
2754
2755 // Note: the calculated starting heap region may be NULL
2756 // (when the collection set is empty).
2757 assert(result == NULL || result->in_collection_set(), "sanity");
2758 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2759 "should be updated only once per pause");
2760 _worker_cset_start_region[worker_i] = result;
2761 OrderAccess::storestore();
2762 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2763 return result;
2764 }
2765
2766 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2767 HeapRegion* r = g1_policy()->collection_set();
2768 while (r != NULL) {
2769 HeapRegion* next = r->next_in_collection_set();
2770 if (cl->doHeapRegion(r)) {
2771 cl->incomplete();
2772 return;
2773 }
2774 r = next;
2775 }
2776 }
2777
2778 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2779 HeapRegionClosure *cl) {
2780 if (r == NULL) {
2781 // The CSet is empty so there's nothing to do.
2782 return;
2783 }
2784
2785 assert(r->in_collection_set(),
2786 "Start region must be a member of the collection set.");
2787 HeapRegion* cur = r;
2788 while (cur != NULL) {
2789 HeapRegion* next = cur->next_in_collection_set();
2790 if (cl->doHeapRegion(cur) && false) {
2791 cl->incomplete();
2792 return;
2793 }
2794 cur = next;
2795 }
2796 cur = g1_policy()->collection_set();
2797 while (cur != r) {
2798 HeapRegion* next = cur->next_in_collection_set();
2799 if (cl->doHeapRegion(cur) && false) {
2800 cl->incomplete();
2801 return;
2802 }
2803 cur = next;
2804 }
2805 }
2806
2807 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2808 HeapRegion* result = _hrm.next_region_in_heap(from);
2809 while (result != NULL && result->is_pinned()) {
2810 result = _hrm.next_region_in_heap(result);
2811 }
2812 return result;
2813 }
2814
2815 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2816 HeapRegion* hr = heap_region_containing(addr);
2817 return hr->block_start(addr);
2818 }
2819
2820 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2821 HeapRegion* hr = heap_region_containing(addr);
2822 return hr->block_size(addr);
2823 }
2824
2825 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2826 HeapRegion* hr = heap_region_containing(addr);
2827 return hr->block_is_obj(addr);
2828 }
2829
2830 bool G1CollectedHeap::supports_tlab_allocation() const {
2831 return true;
2832 }
2833
2834 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2835 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2836 }
2837
2838 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2839 return young_list()->eden_used_bytes();
2840 }
2841
2842 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2843 // must be smaller than the humongous object limit.
2844 size_t G1CollectedHeap::max_tlab_size() const {
2845 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2846 }
2847
2848 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2849 // Return the remaining space in the cur alloc region, but not less than
2850 // the min TLAB size.
2851
2852 // Also, this value can be at most the humongous object threshold,
2853 // since we can't allow tlabs to grow big enough to accommodate
2854 // humongous objects.
2855
2856 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2857 size_t max_tlab = max_tlab_size() * wordSize;
2858 if (hr == NULL) {
2859 return max_tlab;
2860 } else {
2861 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2862 }
2863 }
2864
2865 size_t G1CollectedHeap::max_capacity() const {
2866 return _hrm.reserved().byte_size();
2867 }
2868
2869 jlong G1CollectedHeap::millis_since_last_gc() {
2870 // assert(false, "NYI");
2871 return 0;
2872 }
2873
2874 void G1CollectedHeap::prepare_for_verify() {
2875 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2876 ensure_parsability(false);
2877 }
2878 g1_rem_set()->prepare_for_verify();
2879 }
2880
2881 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2882 VerifyOption vo) {
2883 switch (vo) {
2884 case VerifyOption_G1UsePrevMarking:
2885 return hr->obj_allocated_since_prev_marking(obj);
2886 case VerifyOption_G1UseNextMarking:
2887 return hr->obj_allocated_since_next_marking(obj);
2888 case VerifyOption_G1UseMarkWord:
2889 return false;
2890 default:
2891 ShouldNotReachHere();
2892 }
2893 return false; // keep some compilers happy
2894 }
2895
2896 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2897 switch (vo) {
2898 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2899 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2900 case VerifyOption_G1UseMarkWord: return NULL;
2901 default: ShouldNotReachHere();
2902 }
2903 return NULL; // keep some compilers happy
2904 }
2905
2906 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2907 switch (vo) {
2908 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2909 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2910 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2911 default: ShouldNotReachHere();
2912 }
2913 return false; // keep some compilers happy
2914 }
2915
2916 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2917 switch (vo) {
2918 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2919 case VerifyOption_G1UseNextMarking: return "NTAMS";
2920 case VerifyOption_G1UseMarkWord: return "NONE";
2921 default: ShouldNotReachHere();
2922 }
2923 return NULL; // keep some compilers happy
2924 }
2925
2926 class VerifyRootsClosure: public OopClosure {
2927 private:
2928 G1CollectedHeap* _g1h;
2929 VerifyOption _vo;
2930 bool _failures;
2931 public:
2932 // _vo == UsePrevMarking -> use "prev" marking information,
2933 // _vo == UseNextMarking -> use "next" marking information,
2934 // _vo == UseMarkWord -> use mark word from object header.
2935 VerifyRootsClosure(VerifyOption vo) :
2936 _g1h(G1CollectedHeap::heap()),
2937 _vo(vo),
2938 _failures(false) { }
2939
2940 bool failures() { return _failures; }
2941
2942 template <class T> void do_oop_nv(T* p) {
2943 T heap_oop = oopDesc::load_heap_oop(p);
2944 if (!oopDesc::is_null(heap_oop)) {
2945 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2946 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2947 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2948 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2949 if (_vo == VerifyOption_G1UseMarkWord) {
2950 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2951 }
2952 obj->print_on(gclog_or_tty);
2953 _failures = true;
2954 }
2955 }
2956 }
2957
2958 void do_oop(oop* p) { do_oop_nv(p); }
2959 void do_oop(narrowOop* p) { do_oop_nv(p); }
2960 };
2961
2962 class G1VerifyCodeRootOopClosure: public OopClosure {
2963 G1CollectedHeap* _g1h;
2964 OopClosure* _root_cl;
2965 nmethod* _nm;
2966 VerifyOption _vo;
2967 bool _failures;
2968
2969 template <class T> void do_oop_work(T* p) {
2970 // First verify that this root is live
2971 _root_cl->do_oop(p);
2972
2973 if (!G1VerifyHeapRegionCodeRoots) {
2974 // We're not verifying the code roots attached to heap region.
2975 return;
2976 }
2977
2978 // Don't check the code roots during marking verification in a full GC
2979 if (_vo == VerifyOption_G1UseMarkWord) {
2980 return;
2981 }
2982
2983 // Now verify that the current nmethod (which contains p) is
2984 // in the code root list of the heap region containing the
2985 // object referenced by p.
2986
2987 T heap_oop = oopDesc::load_heap_oop(p);
2988 if (!oopDesc::is_null(heap_oop)) {
2989 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2990
2991 // Now fetch the region containing the object
2992 HeapRegion* hr = _g1h->heap_region_containing(obj);
2993 HeapRegionRemSet* hrrs = hr->rem_set();
2994 // Verify that the strong code root list for this region
2995 // contains the nmethod
2996 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2997 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2998 "from nmethod "PTR_FORMAT" not in strong "
2999 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3000 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3001 _failures = true;
3002 }
3003 }
3004 }
3005
3006 public:
3007 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3008 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3009
3010 void do_oop(oop* p) { do_oop_work(p); }
3011 void do_oop(narrowOop* p) { do_oop_work(p); }
3012
3013 void set_nmethod(nmethod* nm) { _nm = nm; }
3014 bool failures() { return _failures; }
3015 };
3016
3017 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3018 G1VerifyCodeRootOopClosure* _oop_cl;
3019
3020 public:
3021 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3022 _oop_cl(oop_cl) {}
3023
3024 void do_code_blob(CodeBlob* cb) {
3025 nmethod* nm = cb->as_nmethod_or_null();
3026 if (nm != NULL) {
3027 _oop_cl->set_nmethod(nm);
3028 nm->oops_do(_oop_cl);
3029 }
3030 }
3031 };
3032
3033 class YoungRefCounterClosure : public OopClosure {
3034 G1CollectedHeap* _g1h;
3035 int _count;
3036 public:
3037 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3038 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3039 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3040
3041 int count() { return _count; }
3042 void reset_count() { _count = 0; };
3043 };
3044
3045 class VerifyKlassClosure: public KlassClosure {
3046 YoungRefCounterClosure _young_ref_counter_closure;
3047 OopClosure *_oop_closure;
3048 public:
3049 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3050 void do_klass(Klass* k) {
3051 k->oops_do(_oop_closure);
3052
3053 _young_ref_counter_closure.reset_count();
3054 k->oops_do(&_young_ref_counter_closure);
3055 if (_young_ref_counter_closure.count() > 0) {
3056 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3057 }
3058 }
3059 };
3060
3061 class VerifyLivenessOopClosure: public OopClosure {
3062 G1CollectedHeap* _g1h;
3063 VerifyOption _vo;
3064 public:
3065 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3066 _g1h(g1h), _vo(vo)
3067 { }
3068 void do_oop(narrowOop *p) { do_oop_work(p); }
3069 void do_oop( oop *p) { do_oop_work(p); }
3070
3071 template <class T> void do_oop_work(T *p) {
3072 oop obj = oopDesc::load_decode_heap_oop(p);
3073 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3074 "Dead object referenced by a not dead object");
3075 }
3076 };
3077
3078 class VerifyObjsInRegionClosure: public ObjectClosure {
3079 private:
3080 G1CollectedHeap* _g1h;
3081 size_t _live_bytes;
3082 HeapRegion *_hr;
3083 VerifyOption _vo;
3084 public:
3085 // _vo == UsePrevMarking -> use "prev" marking information,
3086 // _vo == UseNextMarking -> use "next" marking information,
3087 // _vo == UseMarkWord -> use mark word from object header.
3088 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3089 : _live_bytes(0), _hr(hr), _vo(vo) {
3090 _g1h = G1CollectedHeap::heap();
3091 }
3092 void do_object(oop o) {
3093 VerifyLivenessOopClosure isLive(_g1h, _vo);
3094 assert(o != NULL, "Huh?");
3095 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3096 // If the object is alive according to the mark word,
3097 // then verify that the marking information agrees.
3098 // Note we can't verify the contra-positive of the
3099 // above: if the object is dead (according to the mark
3100 // word), it may not be marked, or may have been marked
3101 // but has since became dead, or may have been allocated
3102 // since the last marking.
3103 if (_vo == VerifyOption_G1UseMarkWord) {
3104 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3105 }
3106
3107 o->oop_iterate_no_header(&isLive);
3108 if (!_hr->obj_allocated_since_prev_marking(o)) {
3109 size_t obj_size = o->size(); // Make sure we don't overflow
3110 _live_bytes += (obj_size * HeapWordSize);
3111 }
3112 }
3113 }
3114 size_t live_bytes() { return _live_bytes; }
3115 };
3116
3117
3118 class VerifyArchiveOopClosure: public OopClosure {
3119 public:
3120 VerifyArchiveOopClosure(HeapRegion *hr) { }
3121 void do_oop(narrowOop *p) { do_oop_work(p); }
3122 void do_oop( oop *p) { do_oop_work(p); }
3123
3124 template <class T> void do_oop_work(T *p) {
3125 oop obj = oopDesc::load_decode_heap_oop(p);
3126 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3127 "Archive object references a non-pinned object");
3128 }
3129 };
3130
3131 class VerifyArchiveRegionClosure: public ObjectClosure {
3132 public:
3133 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3134 // Verify that all object pointers are to pinned regions.
3135 void do_object(oop o) {
3136 VerifyArchiveOopClosure checkOop(NULL);
3137 assert(o != NULL, "Should not be here for NULL oops");
3138 o->oop_iterate_no_header(&checkOop);
3139 }
3140 };
3141
3142
3143 class VerifyRegionClosure: public HeapRegionClosure {
3144 private:
3145 bool _par;
3146 VerifyOption _vo;
3147 bool _failures;
3148 public:
3149 // _vo == UsePrevMarking -> use "prev" marking information,
3150 // _vo == UseNextMarking -> use "next" marking information,
3151 // _vo == UseMarkWord -> use mark word from object header.
3152 VerifyRegionClosure(bool par, VerifyOption vo)
3153 : _par(par),
3154 _vo(vo),
3155 _failures(false) {}
3156
3157 bool failures() {
3158 return _failures;
3159 }
3160
3161 bool doHeapRegion(HeapRegion* r) {
3162 // For archive regions, verify there are no heap pointers to
3163 // non-pinned regions. For all others, verify liveness info.
3164 if (r->is_archive()) {
3165 VerifyArchiveRegionClosure verify_oop_pointers(r);
3166 r->object_iterate(&verify_oop_pointers);
3167 return true;
3168 }
3169 if (!r->is_continues_humongous()) {
3170 bool failures = false;
3171 r->verify(_vo, &failures);
3172 if (failures) {
3173 _failures = true;
3174 } else {
3175 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3176 r->object_iterate(¬_dead_yet_cl);
3177 if (_vo != VerifyOption_G1UseNextMarking) {
3178 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3179 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3180 "max_live_bytes "SIZE_FORMAT" "
3181 "< calculated "SIZE_FORMAT,
3182 p2i(r->bottom()), p2i(r->end()),
3183 r->max_live_bytes(),
3184 not_dead_yet_cl.live_bytes());
3185 _failures = true;
3186 }
3187 } else {
3188 // When vo == UseNextMarking we cannot currently do a sanity
3189 // check on the live bytes as the calculation has not been
3190 // finalized yet.
3191 }
3192 }
3193 }
3194 return false; // stop the region iteration if we hit a failure
3195 }
3196 };
3197
3198 // This is the task used for parallel verification of the heap regions
3199
3200 class G1ParVerifyTask: public AbstractGangTask {
3201 private:
3202 G1CollectedHeap* _g1h;
3203 VerifyOption _vo;
3204 bool _failures;
3205 HeapRegionClaimer _hrclaimer;
3206
3207 public:
3208 // _vo == UsePrevMarking -> use "prev" marking information,
3209 // _vo == UseNextMarking -> use "next" marking information,
3210 // _vo == UseMarkWord -> use mark word from object header.
3211 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3212 AbstractGangTask("Parallel verify task"),
3213 _g1h(g1h),
3214 _vo(vo),
3215 _failures(false),
3216 _hrclaimer(g1h->workers()->active_workers()) {}
3217
3218 bool failures() {
3219 return _failures;
3220 }
3221
3222 void work(uint worker_id) {
3223 HandleMark hm;
3224 VerifyRegionClosure blk(true, _vo);
3225 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3226 if (blk.failures()) {
3227 _failures = true;
3228 }
3229 }
3230 };
3231
3232 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3233 if (SafepointSynchronize::is_at_safepoint()) {
3234 assert(Thread::current()->is_VM_thread(),
3235 "Expected to be executed serially by the VM thread at this point");
3236
3237 if (!silent) { gclog_or_tty->print("Roots "); }
3238 VerifyRootsClosure rootsCl(vo);
3239 VerifyKlassClosure klassCl(this, &rootsCl);
3240 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3241
3242 // We apply the relevant closures to all the oops in the
3243 // system dictionary, class loader data graph, the string table
3244 // and the nmethods in the code cache.
3245 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3246 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3247
3248 {
3249 G1RootProcessor root_processor(this, 1);
3250 root_processor.process_all_roots(&rootsCl,
3251 &cldCl,
3252 &blobsCl);
3253 }
3254
3255 bool failures = rootsCl.failures() || codeRootsCl.failures();
3256
3257 if (vo != VerifyOption_G1UseMarkWord) {
3258 // If we're verifying during a full GC then the region sets
3259 // will have been torn down at the start of the GC. Therefore
3260 // verifying the region sets will fail. So we only verify
3261 // the region sets when not in a full GC.
3262 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3263 verify_region_sets();
3264 }
3265
3266 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3267 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3268
3269 G1ParVerifyTask task(this, vo);
3270 workers()->run_task(&task);
3271 if (task.failures()) {
3272 failures = true;
3273 }
3274
3275 } else {
3276 VerifyRegionClosure blk(false, vo);
3277 heap_region_iterate(&blk);
3278 if (blk.failures()) {
3279 failures = true;
3280 }
3281 }
3282
3283 if (G1StringDedup::is_enabled()) {
3284 if (!silent) gclog_or_tty->print("StrDedup ");
3285 G1StringDedup::verify();
3286 }
3287
3288 if (failures) {
3289 gclog_or_tty->print_cr("Heap:");
3290 // It helps to have the per-region information in the output to
3291 // help us track down what went wrong. This is why we call
3292 // print_extended_on() instead of print_on().
3293 print_extended_on(gclog_or_tty);
3294 gclog_or_tty->cr();
3295 gclog_or_tty->flush();
3296 }
3297 guarantee(!failures, "there should not have been any failures");
3298 } else {
3299 if (!silent) {
3300 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3301 if (G1StringDedup::is_enabled()) {
3302 gclog_or_tty->print(", StrDedup");
3303 }
3304 gclog_or_tty->print(") ");
3305 }
3306 }
3307 }
3308
3309 void G1CollectedHeap::verify(bool silent) {
3310 verify(silent, VerifyOption_G1UsePrevMarking);
3311 }
3312
3313 double G1CollectedHeap::verify(bool guard, const char* msg) {
3314 double verify_time_ms = 0.0;
3315
3316 if (guard && total_collections() >= VerifyGCStartAt) {
3317 double verify_start = os::elapsedTime();
3318 HandleMark hm; // Discard invalid handles created during verification
3319 prepare_for_verify();
3320 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3321 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3322 }
3323
3324 return verify_time_ms;
3325 }
3326
3327 void G1CollectedHeap::verify_before_gc() {
3328 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3329 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3330 }
3331
3332 void G1CollectedHeap::verify_after_gc() {
3333 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3334 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3335 }
3336
3337 class PrintRegionClosure: public HeapRegionClosure {
3338 outputStream* _st;
3339 public:
3340 PrintRegionClosure(outputStream* st) : _st(st) {}
3341 bool doHeapRegion(HeapRegion* r) {
3342 r->print_on(_st);
3343 return false;
3344 }
3345 };
3346
3347 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3348 const HeapRegion* hr,
3349 const VerifyOption vo) const {
3350 switch (vo) {
3351 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3352 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3353 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3354 default: ShouldNotReachHere();
3355 }
3356 return false; // keep some compilers happy
3357 }
3358
3359 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3360 const VerifyOption vo) const {
3361 switch (vo) {
3362 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3363 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3364 case VerifyOption_G1UseMarkWord: {
3365 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3366 return !obj->is_gc_marked() && !hr->is_archive();
3367 }
3368 default: ShouldNotReachHere();
3369 }
3370 return false; // keep some compilers happy
3371 }
3372
3373 void G1CollectedHeap::print_on(outputStream* st) const {
3374 st->print(" %-20s", "garbage-first heap");
3375 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3376 capacity()/K, used_unlocked()/K);
3377 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3378 p2i(_hrm.reserved().start()),
3379 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3380 p2i(_hrm.reserved().end()));
3381 st->cr();
3382 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3383 uint young_regions = _young_list->length();
3384 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3385 (size_t) young_regions * HeapRegion::GrainBytes / K);
3386 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3387 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3388 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3389 st->cr();
3390 MetaspaceAux::print_on(st);
3391 }
3392
3393 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3394 print_on(st);
3395
3396 // Print the per-region information.
3397 st->cr();
3398 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3399 "HS=humongous(starts), HC=humongous(continues), "
3400 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3401 "PTAMS=previous top-at-mark-start, "
3402 "NTAMS=next top-at-mark-start)");
3403 PrintRegionClosure blk(st);
3404 heap_region_iterate(&blk);
3405 }
3406
3407 void G1CollectedHeap::print_on_error(outputStream* st) const {
3408 this->CollectedHeap::print_on_error(st);
3409
3410 if (_cm != NULL) {
3411 st->cr();
3412 _cm->print_on_error(st);
3413 }
3414 }
3415
3416 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3417 workers()->print_worker_threads_on(st);
3418 _cmThread->print_on(st);
3419 st->cr();
3420 _cm->print_worker_threads_on(st);
3421 _cg1r->print_worker_threads_on(st);
3422 if (G1StringDedup::is_enabled()) {
3423 G1StringDedup::print_worker_threads_on(st);
3424 }
3425 }
3426
3427 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3428 workers()->threads_do(tc);
3429 tc->do_thread(_cmThread);
3430 _cg1r->threads_do(tc);
3431 if (G1StringDedup::is_enabled()) {
3432 G1StringDedup::threads_do(tc);
3433 }
3434 }
3435
3436 void G1CollectedHeap::print_tracing_info() const {
3437 // We'll overload this to mean "trace GC pause statistics."
3438 if (TraceYoungGenTime || TraceOldGenTime) {
3439 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3440 // to that.
3441 g1_policy()->print_tracing_info();
3442 }
3443 if (G1SummarizeRSetStats) {
3444 g1_rem_set()->print_summary_info();
3445 }
3446 if (G1SummarizeConcMark) {
3447 concurrent_mark()->print_summary_info();
3448 }
3449 g1_policy()->print_yg_surv_rate_info();
3450 }
3451
3452 #ifndef PRODUCT
3453 // Helpful for debugging RSet issues.
3454
3455 class PrintRSetsClosure : public HeapRegionClosure {
3456 private:
3457 const char* _msg;
3458 size_t _occupied_sum;
3459
3460 public:
3461 bool doHeapRegion(HeapRegion* r) {
3462 HeapRegionRemSet* hrrs = r->rem_set();
3463 size_t occupied = hrrs->occupied();
3464 _occupied_sum += occupied;
3465
3466 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3467 HR_FORMAT_PARAMS(r));
3468 if (occupied == 0) {
3469 gclog_or_tty->print_cr(" RSet is empty");
3470 } else {
3471 hrrs->print();
3472 }
3473 gclog_or_tty->print_cr("----------");
3474 return false;
3475 }
3476
3477 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3478 gclog_or_tty->cr();
3479 gclog_or_tty->print_cr("========================================");
3480 gclog_or_tty->print_cr("%s", msg);
3481 gclog_or_tty->cr();
3482 }
3483
3484 ~PrintRSetsClosure() {
3485 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3486 gclog_or_tty->print_cr("========================================");
3487 gclog_or_tty->cr();
3488 }
3489 };
3490
3491 void G1CollectedHeap::print_cset_rsets() {
3492 PrintRSetsClosure cl("Printing CSet RSets");
3493 collection_set_iterate(&cl);
3494 }
3495
3496 void G1CollectedHeap::print_all_rsets() {
3497 PrintRSetsClosure cl("Printing All RSets");;
3498 heap_region_iterate(&cl);
3499 }
3500 #endif // PRODUCT
3501
3502 G1CollectedHeap* G1CollectedHeap::heap() {
3503 CollectedHeap* heap = Universe::heap();
3504 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3505 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3506 return (G1CollectedHeap*)heap;
3507 }
3508
3509 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3510 // always_do_update_barrier = false;
3511 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3512 // Fill TLAB's and such
3513 accumulate_statistics_all_tlabs();
3514 ensure_parsability(true);
3515
3516 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3517 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3518 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3519 }
3520 }
3521
3522 void G1CollectedHeap::gc_epilogue(bool full) {
3523
3524 if (G1SummarizeRSetStats &&
3525 (G1SummarizeRSetStatsPeriod > 0) &&
3526 // we are at the end of the GC. Total collections has already been increased.
3527 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3528 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3529 }
3530
3531 // FIXME: what is this about?
3532 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3533 // is set.
3534 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3535 "derived pointer present"));
3536 // always_do_update_barrier = true;
3537
3538 resize_all_tlabs();
3539 allocation_context_stats().update(full);
3540
3541 // We have just completed a GC. Update the soft reference
3542 // policy with the new heap occupancy
3543 Universe::update_heap_info_at_gc();
3544 }
3545
3546 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3547 uint gc_count_before,
3548 bool* succeeded,
3549 GCCause::Cause gc_cause) {
3550 assert_heap_not_locked_and_not_at_safepoint();
3551 g1_policy()->record_stop_world_start();
3552 VM_G1IncCollectionPause op(gc_count_before,
3553 word_size,
3554 false, /* should_initiate_conc_mark */
3555 g1_policy()->max_pause_time_ms(),
3556 gc_cause);
3557
3558 op.set_allocation_context(AllocationContext::current());
3559 VMThread::execute(&op);
3560
3561 HeapWord* result = op.result();
3562 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3563 assert(result == NULL || ret_succeeded,
3564 "the result should be NULL if the VM did not succeed");
3565 *succeeded = ret_succeeded;
3566
3567 assert_heap_not_locked();
3568 return result;
3569 }
3570
3571 void
3572 G1CollectedHeap::doConcurrentMark() {
3573 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3574 if (!_cmThread->in_progress()) {
3575 _cmThread->set_started();
3576 CGC_lock->notify();
3577 }
3578 }
3579
3580 size_t G1CollectedHeap::pending_card_num() {
3581 size_t extra_cards = 0;
3582 JavaThread *curr = Threads::first();
3583 while (curr != NULL) {
3584 DirtyCardQueue& dcq = curr->dirty_card_queue();
3585 extra_cards += dcq.size();
3586 curr = curr->next();
3587 }
3588 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3589 size_t buffer_size = dcqs.buffer_size();
3590 size_t buffer_num = dcqs.completed_buffers_num();
3591
3592 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3593 // in bytes - not the number of 'entries'. We need to convert
3594 // into a number of cards.
3595 return (buffer_size * buffer_num + extra_cards) / oopSize;
3596 }
3597
3598 size_t G1CollectedHeap::cards_scanned() {
3599 return g1_rem_set()->cardsScanned();
3600 }
3601
3602 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3603 private:
3604 size_t _total_humongous;
3605 size_t _candidate_humongous;
3606
3607 DirtyCardQueue _dcq;
3608
3609 // We don't nominate objects with many remembered set entries, on
3610 // the assumption that such objects are likely still live.
3611 bool is_remset_small(HeapRegion* region) const {
3612 HeapRegionRemSet* const rset = region->rem_set();
3613 return G1EagerReclaimHumongousObjectsWithStaleRefs
3614 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3615 : rset->is_empty();
3616 }
3617
3618 bool is_typeArray_region(HeapRegion* region) const {
3619 return oop(region->bottom())->is_typeArray();
3620 }
3621
3622 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3623 assert(region->is_starts_humongous(), "Must start a humongous object");
3624
3625 // Candidate selection must satisfy the following constraints
3626 // while concurrent marking is in progress:
3627 //
3628 // * In order to maintain SATB invariants, an object must not be
3629 // reclaimed if it was allocated before the start of marking and
3630 // has not had its references scanned. Such an object must have
3631 // its references (including type metadata) scanned to ensure no
3632 // live objects are missed by the marking process. Objects
3633 // allocated after the start of concurrent marking don't need to
3634 // be scanned.
3635 //
3636 // * An object must not be reclaimed if it is on the concurrent
3637 // mark stack. Objects allocated after the start of concurrent
3638 // marking are never pushed on the mark stack.
3639 //
3640 // Nominating only objects allocated after the start of concurrent
3641 // marking is sufficient to meet both constraints. This may miss
3642 // some objects that satisfy the constraints, but the marking data
3643 // structures don't support efficiently performing the needed
3644 // additional tests or scrubbing of the mark stack.
3645 //
3646 // However, we presently only nominate is_typeArray() objects.
3647 // A humongous object containing references induces remembered
3648 // set entries on other regions. In order to reclaim such an
3649 // object, those remembered sets would need to be cleaned up.
3650 //
3651 // We also treat is_typeArray() objects specially, allowing them
3652 // to be reclaimed even if allocated before the start of
3653 // concurrent mark. For this we rely on mark stack insertion to
3654 // exclude is_typeArray() objects, preventing reclaiming an object
3655 // that is in the mark stack. We also rely on the metadata for
3656 // such objects to be built-in and so ensured to be kept live.
3657 // Frequent allocation and drop of large binary blobs is an
3658 // important use case for eager reclaim, and this special handling
3659 // may reduce needed headroom.
3660
3661 return is_typeArray_region(region) && is_remset_small(region);
3662 }
3663
3664 public:
3665 RegisterHumongousWithInCSetFastTestClosure()
3666 : _total_humongous(0),
3667 _candidate_humongous(0),
3668 _dcq(&JavaThread::dirty_card_queue_set()) {
3669 }
3670
3671 virtual bool doHeapRegion(HeapRegion* r) {
3672 if (!r->is_starts_humongous()) {
3673 return false;
3674 }
3675 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3676
3677 bool is_candidate = humongous_region_is_candidate(g1h, r);
3678 uint rindex = r->hrm_index();
3679 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3680 if (is_candidate) {
3681 _candidate_humongous++;
3682 g1h->register_humongous_region_with_cset(rindex);
3683 // Is_candidate already filters out humongous object with large remembered sets.
3684 // If we have a humongous object with a few remembered sets, we simply flush these
3685 // remembered set entries into the DCQS. That will result in automatic
3686 // re-evaluation of their remembered set entries during the following evacuation
3687 // phase.
3688 if (!r->rem_set()->is_empty()) {
3689 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3690 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3691 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3692 HeapRegionRemSetIterator hrrs(r->rem_set());
3693 size_t card_index;
3694 while (hrrs.has_next(card_index)) {
3695 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3696 // The remembered set might contain references to already freed
3697 // regions. Filter out such entries to avoid failing card table
3698 // verification.
3699 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3700 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3701 *card_ptr = CardTableModRefBS::dirty_card_val();
3702 _dcq.enqueue(card_ptr);
3703 }
3704 }
3705 }
3706 r->rem_set()->clear_locked();
3707 }
3708 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3709 }
3710 _total_humongous++;
3711
3712 return false;
3713 }
3714
3715 size_t total_humongous() const { return _total_humongous; }
3716 size_t candidate_humongous() const { return _candidate_humongous; }
3717
3718 void flush_rem_set_entries() { _dcq.flush(); }
3719 };
3720
3721 void G1CollectedHeap::register_humongous_regions_with_cset() {
3722 if (!G1EagerReclaimHumongousObjects) {
3723 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3724 return;
3725 }
3726 double time = os::elapsed_counter();
3727
3728 // Collect reclaim candidate information and register candidates with cset.
3729 RegisterHumongousWithInCSetFastTestClosure cl;
3730 heap_region_iterate(&cl);
3731
3732 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3733 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3734 cl.total_humongous(),
3735 cl.candidate_humongous());
3736 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3737
3738 // Finally flush all remembered set entries to re-check into the global DCQS.
3739 cl.flush_rem_set_entries();
3740 }
3741
3742 void
3743 G1CollectedHeap::setup_surviving_young_words() {
3744 assert(_surviving_young_words == NULL, "pre-condition");
3745 uint array_length = g1_policy()->young_cset_region_length();
3746 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3747 if (_surviving_young_words == NULL) {
3748 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3749 "Not enough space for young surv words summary.");
3750 }
3751 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3752 #ifdef ASSERT
3753 for (uint i = 0; i < array_length; ++i) {
3754 assert( _surviving_young_words[i] == 0, "memset above" );
3755 }
3756 #endif // !ASSERT
3757 }
3758
3759 void
3760 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3761 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3762 uint array_length = g1_policy()->young_cset_region_length();
3763 for (uint i = 0; i < array_length; ++i) {
3764 _surviving_young_words[i] += surv_young_words[i];
3765 }
3766 }
3767
3768 void
3769 G1CollectedHeap::cleanup_surviving_young_words() {
3770 guarantee( _surviving_young_words != NULL, "pre-condition" );
3771 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3772 _surviving_young_words = NULL;
3773 }
3774
3775 #ifdef ASSERT
3776 class VerifyCSetClosure: public HeapRegionClosure {
3777 public:
3778 bool doHeapRegion(HeapRegion* hr) {
3779 // Here we check that the CSet region's RSet is ready for parallel
3780 // iteration. The fields that we'll verify are only manipulated
3781 // when the region is part of a CSet and is collected. Afterwards,
3782 // we reset these fields when we clear the region's RSet (when the
3783 // region is freed) so they are ready when the region is
3784 // re-allocated. The only exception to this is if there's an
3785 // evacuation failure and instead of freeing the region we leave
3786 // it in the heap. In that case, we reset these fields during
3787 // evacuation failure handling.
3788 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3789
3790 // Here's a good place to add any other checks we'd like to
3791 // perform on CSet regions.
3792 return false;
3793 }
3794 };
3795 #endif // ASSERT
3796
3797 uint G1CollectedHeap::num_task_queues() const {
3798 return _task_queues->size();
3799 }
3800
3801 #if TASKQUEUE_STATS
3802 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3803 st->print_raw_cr("GC Task Stats");
3804 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3805 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3806 }
3807
3808 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3809 print_taskqueue_stats_hdr(st);
3810
3811 TaskQueueStats totals;
3812 const uint n = num_task_queues();
3813 for (uint i = 0; i < n; ++i) {
3814 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3815 totals += task_queue(i)->stats;
3816 }
3817 st->print_raw("tot "); totals.print(st); st->cr();
3818
3819 DEBUG_ONLY(totals.verify());
3820 }
3821
3822 void G1CollectedHeap::reset_taskqueue_stats() {
3823 const uint n = num_task_queues();
3824 for (uint i = 0; i < n; ++i) {
3825 task_queue(i)->stats.reset();
3826 }
3827 }
3828 #endif // TASKQUEUE_STATS
3829
3830 void G1CollectedHeap::log_gc_header() {
3831 if (!G1Log::fine()) {
3832 return;
3833 }
3834
3835 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3836
3837 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3838 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3839 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3840
3841 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3842 }
3843
3844 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3845 if (!G1Log::fine()) {
3846 return;
3847 }
3848
3849 if (G1Log::finer()) {
3850 if (evacuation_failed()) {
3851 gclog_or_tty->print(" (to-space exhausted)");
3852 }
3853 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3854 g1_policy()->phase_times()->note_gc_end();
3855 g1_policy()->phase_times()->print(pause_time_sec);
3856 g1_policy()->print_detailed_heap_transition();
3857 } else {
3858 if (evacuation_failed()) {
3859 gclog_or_tty->print("--");
3860 }
3861 g1_policy()->print_heap_transition();
3862 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3863 }
3864 gclog_or_tty->flush();
3865 }
3866
3867 bool
3868 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3869 assert_at_safepoint(true /* should_be_vm_thread */);
3870 guarantee(!is_gc_active(), "collection is not reentrant");
3871
3872 if (GC_locker::check_active_before_gc()) {
3873 return false;
3874 }
3875
3876 _gc_timer_stw->register_gc_start();
3877
3878 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3879
3880 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3881 ResourceMark rm;
3882
3883 G1Log::update_level();
3884 print_heap_before_gc();
3885 trace_heap_before_gc(_gc_tracer_stw);
3886
3887 verify_region_sets_optional();
3888 verify_dirty_young_regions();
3889
3890 // This call will decide whether this pause is an initial-mark
3891 // pause. If it is, during_initial_mark_pause() will return true
3892 // for the duration of this pause.
3893 g1_policy()->decide_on_conc_mark_initiation();
3894
3895 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3896 assert(!g1_policy()->during_initial_mark_pause() ||
3897 g1_policy()->gcs_are_young(), "sanity");
3898
3899 // We also do not allow mixed GCs during marking.
3900 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3901
3902 // Record whether this pause is an initial mark. When the current
3903 // thread has completed its logging output and it's safe to signal
3904 // the CM thread, the flag's value in the policy has been reset.
3905 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3906
3907 // Inner scope for scope based logging, timers, and stats collection
3908 {
3909 EvacuationInfo evacuation_info;
3910
3911 if (g1_policy()->during_initial_mark_pause()) {
3912 // We are about to start a marking cycle, so we increment the
3913 // full collection counter.
3914 increment_old_marking_cycles_started();
3915 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3916 }
3917
3918 _gc_tracer_stw->report_yc_type(yc_type());
3919
3920 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3921
3922 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3923 workers()->active_workers(),
3924 Threads::number_of_non_daemon_threads());
3925 workers()->set_active_workers(active_workers);
3926
3927 double pause_start_sec = os::elapsedTime();
3928 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3929 log_gc_header();
3930
3931 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3932 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3933
3934 // If the secondary_free_list is not empty, append it to the
3935 // free_list. No need to wait for the cleanup operation to finish;
3936 // the region allocation code will check the secondary_free_list
3937 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3938 // set, skip this step so that the region allocation code has to
3939 // get entries from the secondary_free_list.
3940 if (!G1StressConcRegionFreeing) {
3941 append_secondary_free_list_if_not_empty_with_lock();
3942 }
3943
3944 assert(check_young_list_well_formed(), "young list should be well formed");
3945
3946 // Don't dynamically change the number of GC threads this early. A value of
3947 // 0 is used to indicate serial work. When parallel work is done,
3948 // it will be set.
3949
3950 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3951 IsGCActiveMark x;
3952
3953 gc_prologue(false);
3954 increment_total_collections(false /* full gc */);
3955 increment_gc_time_stamp();
3956
3957 verify_before_gc();
3958
3959 check_bitmaps("GC Start");
3960
3961 COMPILER2_PRESENT(DerivedPointerTable::clear());
3962
3963 // Please see comment in g1CollectedHeap.hpp and
3964 // G1CollectedHeap::ref_processing_init() to see how
3965 // reference processing currently works in G1.
3966
3967 // Enable discovery in the STW reference processor
3968 ref_processor_stw()->enable_discovery();
3969
3970 {
3971 // We want to temporarily turn off discovery by the
3972 // CM ref processor, if necessary, and turn it back on
3973 // on again later if we do. Using a scoped
3974 // NoRefDiscovery object will do this.
3975 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3976
3977 // Forget the current alloc region (we might even choose it to be part
3978 // of the collection set!).
3979 _allocator->release_mutator_alloc_region();
3980
3981 // We should call this after we retire the mutator alloc
3982 // region(s) so that all the ALLOC / RETIRE events are generated
3983 // before the start GC event.
3984 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3985
3986 // This timing is only used by the ergonomics to handle our pause target.
3987 // It is unclear why this should not include the full pause. We will
3988 // investigate this in CR 7178365.
3989 //
3990 // Preserving the old comment here if that helps the investigation:
3991 //
3992 // The elapsed time induced by the start time below deliberately elides
3993 // the possible verification above.
3994 double sample_start_time_sec = os::elapsedTime();
3995
3996 #if YOUNG_LIST_VERBOSE
3997 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3998 _young_list->print();
3999 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4000 #endif // YOUNG_LIST_VERBOSE
4001
4002 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4003
4004 double scan_wait_start = os::elapsedTime();
4005 // We have to wait until the CM threads finish scanning the
4006 // root regions as it's the only way to ensure that all the
4007 // objects on them have been correctly scanned before we start
4008 // moving them during the GC.
4009 bool waited = _cm->root_regions()->wait_until_scan_finished();
4010 double wait_time_ms = 0.0;
4011 if (waited) {
4012 double scan_wait_end = os::elapsedTime();
4013 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4014 }
4015 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4016
4017 #if YOUNG_LIST_VERBOSE
4018 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4019 _young_list->print();
4020 #endif // YOUNG_LIST_VERBOSE
4021
4022 if (g1_policy()->during_initial_mark_pause()) {
4023 concurrent_mark()->checkpointRootsInitialPre();
4024 }
4025
4026 #if YOUNG_LIST_VERBOSE
4027 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4028 _young_list->print();
4029 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4030 #endif // YOUNG_LIST_VERBOSE
4031
4032 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4033
4034 register_humongous_regions_with_cset();
4035
4036 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4037
4038 _cm->note_start_of_gc();
4039 // We call this after finalize_cset() to
4040 // ensure that the CSet has been finalized.
4041 _cm->verify_no_cset_oops();
4042
4043 if (_hr_printer.is_active()) {
4044 HeapRegion* hr = g1_policy()->collection_set();
4045 while (hr != NULL) {
4046 _hr_printer.cset(hr);
4047 hr = hr->next_in_collection_set();
4048 }
4049 }
4050
4051 #ifdef ASSERT
4052 VerifyCSetClosure cl;
4053 collection_set_iterate(&cl);
4054 #endif // ASSERT
4055
4056 setup_surviving_young_words();
4057
4058 // Initialize the GC alloc regions.
4059 _allocator->init_gc_alloc_regions(evacuation_info);
4060
4061 // Actually do the work...
4062 evacuate_collection_set(evacuation_info);
4063
4064 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4065
4066 eagerly_reclaim_humongous_regions();
4067
4068 g1_policy()->clear_collection_set();
4069
4070 cleanup_surviving_young_words();
4071
4072 // Start a new incremental collection set for the next pause.
4073 g1_policy()->start_incremental_cset_building();
4074
4075 clear_cset_fast_test();
4076
4077 _young_list->reset_sampled_info();
4078
4079 // Don't check the whole heap at this point as the
4080 // GC alloc regions from this pause have been tagged
4081 // as survivors and moved on to the survivor list.
4082 // Survivor regions will fail the !is_young() check.
4083 assert(check_young_list_empty(false /* check_heap */),
4084 "young list should be empty");
4085
4086 #if YOUNG_LIST_VERBOSE
4087 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4088 _young_list->print();
4089 #endif // YOUNG_LIST_VERBOSE
4090
4091 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4092 _young_list->first_survivor_region(),
4093 _young_list->last_survivor_region());
4094
4095 _young_list->reset_auxilary_lists();
4096
4097 if (evacuation_failed()) {
4098 _allocator->set_used(recalculate_used());
4099 if (_archive_allocator != NULL) {
4100 _archive_allocator->clear_used();
4101 }
4102 for (uint i = 0; i < ParallelGCThreads; i++) {
4103 if (_evacuation_failed_info_array[i].has_failed()) {
4104 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4105 }
4106 }
4107 } else {
4108 // The "used" of the the collection set have already been subtracted
4109 // when they were freed. Add in the bytes evacuated.
4110 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4111 }
4112
4113 if (g1_policy()->during_initial_mark_pause()) {
4114 // We have to do this before we notify the CM threads that
4115 // they can start working to make sure that all the
4116 // appropriate initialization is done on the CM object.
4117 concurrent_mark()->checkpointRootsInitialPost();
4118 set_marking_started();
4119 // Note that we don't actually trigger the CM thread at
4120 // this point. We do that later when we're sure that
4121 // the current thread has completed its logging output.
4122 }
4123
4124 allocate_dummy_regions();
4125
4126 #if YOUNG_LIST_VERBOSE
4127 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4128 _young_list->print();
4129 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4130 #endif // YOUNG_LIST_VERBOSE
4131
4132 _allocator->init_mutator_alloc_region();
4133
4134 {
4135 size_t expand_bytes = g1_policy()->expansion_amount();
4136 if (expand_bytes > 0) {
4137 size_t bytes_before = capacity();
4138 // No need for an ergo verbose message here,
4139 // expansion_amount() does this when it returns a value > 0.
4140 if (!expand(expand_bytes)) {
4141 // We failed to expand the heap. Cannot do anything about it.
4142 }
4143 }
4144 }
4145
4146 // We redo the verification but now wrt to the new CSet which
4147 // has just got initialized after the previous CSet was freed.
4148 _cm->verify_no_cset_oops();
4149 _cm->note_end_of_gc();
4150
4151 // This timing is only used by the ergonomics to handle our pause target.
4152 // It is unclear why this should not include the full pause. We will
4153 // investigate this in CR 7178365.
4154 double sample_end_time_sec = os::elapsedTime();
4155 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4156 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4157
4158 MemoryService::track_memory_usage();
4159
4160 // In prepare_for_verify() below we'll need to scan the deferred
4161 // update buffers to bring the RSets up-to-date if
4162 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4163 // the update buffers we'll probably need to scan cards on the
4164 // regions we just allocated to (i.e., the GC alloc
4165 // regions). However, during the last GC we called
4166 // set_saved_mark() on all the GC alloc regions, so card
4167 // scanning might skip the [saved_mark_word()...top()] area of
4168 // those regions (i.e., the area we allocated objects into
4169 // during the last GC). But it shouldn't. Given that
4170 // saved_mark_word() is conditional on whether the GC time stamp
4171 // on the region is current or not, by incrementing the GC time
4172 // stamp here we invalidate all the GC time stamps on all the
4173 // regions and saved_mark_word() will simply return top() for
4174 // all the regions. This is a nicer way of ensuring this rather
4175 // than iterating over the regions and fixing them. In fact, the
4176 // GC time stamp increment here also ensures that
4177 // saved_mark_word() will return top() between pauses, i.e.,
4178 // during concurrent refinement. So we don't need the
4179 // is_gc_active() check to decided which top to use when
4180 // scanning cards (see CR 7039627).
4181 increment_gc_time_stamp();
4182
4183 verify_after_gc();
4184 check_bitmaps("GC End");
4185
4186 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4187 ref_processor_stw()->verify_no_references_recorded();
4188
4189 // CM reference discovery will be re-enabled if necessary.
4190 }
4191
4192 // We should do this after we potentially expand the heap so
4193 // that all the COMMIT events are generated before the end GC
4194 // event, and after we retire the GC alloc regions so that all
4195 // RETIRE events are generated before the end GC event.
4196 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4197
4198 #ifdef TRACESPINNING
4199 ParallelTaskTerminator::print_termination_counts();
4200 #endif
4201
4202 gc_epilogue(false);
4203 }
4204
4205 // Print the remainder of the GC log output.
4206 log_gc_footer(os::elapsedTime() - pause_start_sec);
4207
4208 // It is not yet to safe to tell the concurrent mark to
4209 // start as we have some optional output below. We don't want the
4210 // output from the concurrent mark thread interfering with this
4211 // logging output either.
4212
4213 _hrm.verify_optional();
4214 verify_region_sets_optional();
4215
4216 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4217 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4218
4219 print_heap_after_gc();
4220 trace_heap_after_gc(_gc_tracer_stw);
4221
4222 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4223 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4224 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4225 // before any GC notifications are raised.
4226 g1mm()->update_sizes();
4227
4228 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4229 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4230 _gc_timer_stw->register_gc_end();
4231 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4232 }
4233 // It should now be safe to tell the concurrent mark thread to start
4234 // without its logging output interfering with the logging output
4235 // that came from the pause.
4236
4237 if (should_start_conc_mark) {
4238 // CAUTION: after the doConcurrentMark() call below,
4239 // the concurrent marking thread(s) could be running
4240 // concurrently with us. Make sure that anything after
4241 // this point does not assume that we are the only GC thread
4242 // running. Note: of course, the actual marking work will
4243 // not start until the safepoint itself is released in
4244 // SuspendibleThreadSet::desynchronize().
4245 doConcurrentMark();
4246 }
4247
4248 return true;
4249 }
4250
4251 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4252 _drain_in_progress = false;
4253 set_evac_failure_closure(cl);
4254 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4255 }
4256
4257 void G1CollectedHeap::finalize_for_evac_failure() {
4258 assert(_evac_failure_scan_stack != NULL &&
4259 _evac_failure_scan_stack->length() == 0,
4260 "Postcondition");
4261 assert(!_drain_in_progress, "Postcondition");
4262 delete _evac_failure_scan_stack;
4263 _evac_failure_scan_stack = NULL;
4264 }
4265
4266 void G1CollectedHeap::remove_self_forwarding_pointers() {
4267 double remove_self_forwards_start = os::elapsedTime();
4268
4269 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4270 workers()->run_task(&rsfp_task);
4271
4272 // Now restore saved marks, if any.
4273 assert(_objs_with_preserved_marks.size() ==
4274 _preserved_marks_of_objs.size(), "Both or none.");
4275 while (!_objs_with_preserved_marks.is_empty()) {
4276 oop obj = _objs_with_preserved_marks.pop();
4277 markOop m = _preserved_marks_of_objs.pop();
4278 obj->set_mark(m);
4279 }
4280 _objs_with_preserved_marks.clear(true);
4281 _preserved_marks_of_objs.clear(true);
4282
4283 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4284 }
4285
4286 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4287 _evac_failure_scan_stack->push(obj);
4288 }
4289
4290 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4291 assert(_evac_failure_scan_stack != NULL, "precondition");
4292
4293 while (_evac_failure_scan_stack->length() > 0) {
4294 oop obj = _evac_failure_scan_stack->pop();
4295 _evac_failure_closure->set_region(heap_region_containing(obj));
4296 obj->oop_iterate_backwards(_evac_failure_closure);
4297 }
4298 }
4299
4300 oop
4301 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4302 oop old) {
4303 assert(obj_in_cs(old),
4304 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4305 p2i(old)));
4306 markOop m = old->mark();
4307 oop forward_ptr = old->forward_to_atomic(old);
4308 if (forward_ptr == NULL) {
4309 // Forward-to-self succeeded.
4310 assert(_par_scan_state != NULL, "par scan state");
4311 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4312 uint queue_num = _par_scan_state->queue_num();
4313
4314 _evacuation_failed = true;
4315 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4316 if (_evac_failure_closure != cl) {
4317 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4318 assert(!_drain_in_progress,
4319 "Should only be true while someone holds the lock.");
4320 // Set the global evac-failure closure to the current thread's.
4321 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4322 set_evac_failure_closure(cl);
4323 // Now do the common part.
4324 handle_evacuation_failure_common(old, m);
4325 // Reset to NULL.
4326 set_evac_failure_closure(NULL);
4327 } else {
4328 // The lock is already held, and this is recursive.
4329 assert(_drain_in_progress, "This should only be the recursive case.");
4330 handle_evacuation_failure_common(old, m);
4331 }
4332 return old;
4333 } else {
4334 // Forward-to-self failed. Either someone else managed to allocate
4335 // space for this object (old != forward_ptr) or they beat us in
4336 // self-forwarding it (old == forward_ptr).
4337 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4338 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4339 "should not be in the CSet",
4340 p2i(old), p2i(forward_ptr)));
4341 return forward_ptr;
4342 }
4343 }
4344
4345 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4346 preserve_mark_if_necessary(old, m);
4347
4348 HeapRegion* r = heap_region_containing(old);
4349 if (!r->evacuation_failed()) {
4350 r->set_evacuation_failed(true);
4351 _hr_printer.evac_failure(r);
4352 }
4353
4354 push_on_evac_failure_scan_stack(old);
4355
4356 if (!_drain_in_progress) {
4357 // prevent recursion in copy_to_survivor_space()
4358 _drain_in_progress = true;
4359 drain_evac_failure_scan_stack();
4360 _drain_in_progress = false;
4361 }
4362 }
4363
4364 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4365 assert(evacuation_failed(), "Oversaving!");
4366 // We want to call the "for_promotion_failure" version only in the
4367 // case of a promotion failure.
4368 if (m->must_be_preserved_for_promotion_failure(obj)) {
4369 _objs_with_preserved_marks.push(obj);
4370 _preserved_marks_of_objs.push(m);
4371 }
4372 }
4373
4374 void G1ParCopyHelper::mark_object(oop obj) {
4375 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4376
4377 // We know that the object is not moving so it's safe to read its size.
4378 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4379 }
4380
4381 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4382 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4383 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4384 assert(from_obj != to_obj, "should not be self-forwarded");
4385
4386 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4387 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4388
4389 // The object might be in the process of being copied by another
4390 // worker so we cannot trust that its to-space image is
4391 // well-formed. So we have to read its size from its from-space
4392 // image which we know should not be changing.
4393 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4394 }
4395
4396 template <class T>
4397 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4398 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4399 _scanned_klass->record_modified_oops();
4400 }
4401 }
4402
4403 template <G1Barrier barrier, G1Mark do_mark_object>
4404 template <class T>
4405 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4406 T heap_oop = oopDesc::load_heap_oop(p);
4407
4408 if (oopDesc::is_null(heap_oop)) {
4409 return;
4410 }
4411
4412 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4413
4414 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4415
4416 const InCSetState state = _g1->in_cset_state(obj);
4417 if (state.is_in_cset()) {
4418 oop forwardee;
4419 markOop m = obj->mark();
4420 if (m->is_marked()) {
4421 forwardee = (oop) m->decode_pointer();
4422 } else {
4423 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4424 }
4425 assert(forwardee != NULL, "forwardee should not be NULL");
4426 oopDesc::encode_store_heap_oop(p, forwardee);
4427 if (do_mark_object != G1MarkNone && forwardee != obj) {
4428 // If the object is self-forwarded we don't need to explicitly
4429 // mark it, the evacuation failure protocol will do so.
4430 mark_forwarded_object(obj, forwardee);
4431 }
4432
4433 if (barrier == G1BarrierKlass) {
4434 do_klass_barrier(p, forwardee);
4435 }
4436 } else {
4437 if (state.is_humongous()) {
4438 _g1->set_humongous_is_live(obj);
4439 }
4440 // The object is not in collection set. If we're a root scanning
4441 // closure during an initial mark pause then attempt to mark the object.
4442 if (do_mark_object == G1MarkFromRoot) {
4443 mark_object(obj);
4444 }
4445 }
4446
4447 if (barrier == G1BarrierEvac) {
4448 _par_scan_state->update_rs(_from, p, _worker_id);
4449 }
4450 }
4451
4452 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4453 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4454
4455 class G1ParEvacuateFollowersClosure : public VoidClosure {
4456 protected:
4457 G1CollectedHeap* _g1h;
4458 G1ParScanThreadState* _par_scan_state;
4459 RefToScanQueueSet* _queues;
4460 ParallelTaskTerminator* _terminator;
4461
4462 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4463 RefToScanQueueSet* queues() { return _queues; }
4464 ParallelTaskTerminator* terminator() { return _terminator; }
4465
4466 public:
4467 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4468 G1ParScanThreadState* par_scan_state,
4469 RefToScanQueueSet* queues,
4470 ParallelTaskTerminator* terminator)
4471 : _g1h(g1h), _par_scan_state(par_scan_state),
4472 _queues(queues), _terminator(terminator) {}
4473
4474 void do_void();
4475
4476 private:
4477 inline bool offer_termination();
4478 };
4479
4480 bool G1ParEvacuateFollowersClosure::offer_termination() {
4481 G1ParScanThreadState* const pss = par_scan_state();
4482 pss->start_term_time();
4483 const bool res = terminator()->offer_termination();
4484 pss->end_term_time();
4485 return res;
4486 }
4487
4488 void G1ParEvacuateFollowersClosure::do_void() {
4489 G1ParScanThreadState* const pss = par_scan_state();
4490 pss->trim_queue();
4491 do {
4492 pss->steal_and_trim_queue(queues());
4493 } while (!offer_termination());
4494 }
4495
4496 class G1KlassScanClosure : public KlassClosure {
4497 G1ParCopyHelper* _closure;
4498 bool _process_only_dirty;
4499 int _count;
4500 public:
4501 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4502 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4503 void do_klass(Klass* klass) {
4504 // If the klass has not been dirtied we know that there's
4505 // no references into the young gen and we can skip it.
4506 if (!_process_only_dirty || klass->has_modified_oops()) {
4507 // Clean the klass since we're going to scavenge all the metadata.
4508 klass->clear_modified_oops();
4509
4510 // Tell the closure that this klass is the Klass to scavenge
4511 // and is the one to dirty if oops are left pointing into the young gen.
4512 _closure->set_scanned_klass(klass);
4513
4514 klass->oops_do(_closure);
4515
4516 _closure->set_scanned_klass(NULL);
4517 }
4518 _count++;
4519 }
4520 };
4521
4522 class G1ParTask : public AbstractGangTask {
4523 protected:
4524 G1CollectedHeap* _g1h;
4525 RefToScanQueueSet *_queues;
4526 G1RootProcessor* _root_processor;
4527 ParallelTaskTerminator _terminator;
4528 uint _n_workers;
4529
4530 Mutex _stats_lock;
4531 Mutex* stats_lock() { return &_stats_lock; }
4532
4533 public:
4534 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4535 : AbstractGangTask("G1 collection"),
4536 _g1h(g1h),
4537 _queues(task_queues),
4538 _root_processor(root_processor),
4539 _terminator(n_workers, _queues),
4540 _n_workers(n_workers),
4541 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4542 {}
4543
4544 RefToScanQueueSet* queues() { return _queues; }
4545
4546 RefToScanQueue *work_queue(int i) {
4547 return queues()->queue(i);
4548 }
4549
4550 ParallelTaskTerminator* terminator() { return &_terminator; }
4551
4552 // Helps out with CLD processing.
4553 //
4554 // During InitialMark we need to:
4555 // 1) Scavenge all CLDs for the young GC.
4556 // 2) Mark all objects directly reachable from strong CLDs.
4557 template <G1Mark do_mark_object>
4558 class G1CLDClosure : public CLDClosure {
4559 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4560 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4561 G1KlassScanClosure _klass_in_cld_closure;
4562 bool _claim;
4563
4564 public:
4565 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4566 bool only_young, bool claim)
4567 : _oop_closure(oop_closure),
4568 _oop_in_klass_closure(oop_closure->g1(),
4569 oop_closure->pss(),
4570 oop_closure->rp()),
4571 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4572 _claim(claim) {
4573
4574 }
4575
4576 void do_cld(ClassLoaderData* cld) {
4577 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4578 }
4579 };
4580
4581 void work(uint worker_id) {
4582 if (worker_id >= _n_workers) return; // no work needed this round
4583
4584 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4585
4586 {
4587 ResourceMark rm;
4588 HandleMark hm;
4589
4590 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4591
4592 G1ParScanThreadState pss(_g1h, worker_id, rp);
4593 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4594
4595 pss.set_evac_failure_closure(&evac_failure_cl);
4596
4597 bool only_young = _g1h->g1_policy()->gcs_are_young();
4598
4599 // Non-IM young GC.
4600 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4601 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4602 only_young, // Only process dirty klasses.
4603 false); // No need to claim CLDs.
4604 // IM young GC.
4605 // Strong roots closures.
4606 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4607 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4608 false, // Process all klasses.
4609 true); // Need to claim CLDs.
4610 // Weak roots closures.
4611 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4612 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4613 false, // Process all klasses.
4614 true); // Need to claim CLDs.
4615
4616 OopClosure* strong_root_cl;
4617 OopClosure* weak_root_cl;
4618 CLDClosure* strong_cld_cl;
4619 CLDClosure* weak_cld_cl;
4620
4621 bool trace_metadata = false;
4622
4623 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4624 // We also need to mark copied objects.
4625 strong_root_cl = &scan_mark_root_cl;
4626 strong_cld_cl = &scan_mark_cld_cl;
4627 if (ClassUnloadingWithConcurrentMark) {
4628 weak_root_cl = &scan_mark_weak_root_cl;
4629 weak_cld_cl = &scan_mark_weak_cld_cl;
4630 trace_metadata = true;
4631 } else {
4632 weak_root_cl = &scan_mark_root_cl;
4633 weak_cld_cl = &scan_mark_cld_cl;
4634 }
4635 } else {
4636 strong_root_cl = &scan_only_root_cl;
4637 weak_root_cl = &scan_only_root_cl;
4638 strong_cld_cl = &scan_only_cld_cl;
4639 weak_cld_cl = &scan_only_cld_cl;
4640 }
4641
4642 pss.start_strong_roots();
4643
4644 _root_processor->evacuate_roots(strong_root_cl,
4645 weak_root_cl,
4646 strong_cld_cl,
4647 weak_cld_cl,
4648 trace_metadata,
4649 worker_id);
4650
4651 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4652 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4653 weak_root_cl,
4654 worker_id);
4655 pss.end_strong_roots();
4656
4657 {
4658 double start = os::elapsedTime();
4659 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4660 evac.do_void();
4661 double elapsed_sec = os::elapsedTime() - start;
4662 double term_sec = pss.term_time();
4663 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4664 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4665 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4666 }
4667 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4668 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4669
4670 if (PrintTerminationStats) {
4671 MutexLocker x(stats_lock());
4672 pss.print_termination_stats(worker_id);
4673 }
4674
4675 assert(pss.queue_is_empty(), "should be empty");
4676
4677 // Close the inner scope so that the ResourceMark and HandleMark
4678 // destructors are executed here and are included as part of the
4679 // "GC Worker Time".
4680 }
4681 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4682 }
4683 };
4684
4685 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4686 private:
4687 BoolObjectClosure* _is_alive;
4688 int _initial_string_table_size;
4689 int _initial_symbol_table_size;
4690
4691 bool _process_strings;
4692 int _strings_processed;
4693 int _strings_removed;
4694
4695 bool _process_symbols;
4696 int _symbols_processed;
4697 int _symbols_removed;
4698
4699 public:
4700 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4701 AbstractGangTask("String/Symbol Unlinking"),
4702 _is_alive(is_alive),
4703 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4704 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4705
4706 _initial_string_table_size = StringTable::the_table()->table_size();
4707 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4708 if (process_strings) {
4709 StringTable::clear_parallel_claimed_index();
4710 }
4711 if (process_symbols) {
4712 SymbolTable::clear_parallel_claimed_index();
4713 }
4714 }
4715
4716 ~G1StringSymbolTableUnlinkTask() {
4717 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4718 err_msg("claim value %d after unlink less than initial string table size %d",
4719 StringTable::parallel_claimed_index(), _initial_string_table_size));
4720 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4721 err_msg("claim value %d after unlink less than initial symbol table size %d",
4722 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4723
4724 if (G1TraceStringSymbolTableScrubbing) {
4725 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4726 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4727 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4728 strings_processed(), strings_removed(),
4729 symbols_processed(), symbols_removed());
4730 }
4731 }
4732
4733 void work(uint worker_id) {
4734 int strings_processed = 0;
4735 int strings_removed = 0;
4736 int symbols_processed = 0;
4737 int symbols_removed = 0;
4738 if (_process_strings) {
4739 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4740 Atomic::add(strings_processed, &_strings_processed);
4741 Atomic::add(strings_removed, &_strings_removed);
4742 }
4743 if (_process_symbols) {
4744 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4745 Atomic::add(symbols_processed, &_symbols_processed);
4746 Atomic::add(symbols_removed, &_symbols_removed);
4747 }
4748 }
4749
4750 size_t strings_processed() const { return (size_t)_strings_processed; }
4751 size_t strings_removed() const { return (size_t)_strings_removed; }
4752
4753 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4754 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4755 };
4756
4757 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4758 private:
4759 static Monitor* _lock;
4760
4761 BoolObjectClosure* const _is_alive;
4762 const bool _unloading_occurred;
4763 const uint _num_workers;
4764
4765 // Variables used to claim nmethods.
4766 nmethod* _first_nmethod;
4767 volatile nmethod* _claimed_nmethod;
4768
4769 // The list of nmethods that need to be processed by the second pass.
4770 volatile nmethod* _postponed_list;
4771 volatile uint _num_entered_barrier;
4772
4773 public:
4774 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4775 _is_alive(is_alive),
4776 _unloading_occurred(unloading_occurred),
4777 _num_workers(num_workers),
4778 _first_nmethod(NULL),
4779 _claimed_nmethod(NULL),
4780 _postponed_list(NULL),
4781 _num_entered_barrier(0)
4782 {
4783 nmethod::increase_unloading_clock();
4784 // Get first alive nmethod
4785 NMethodIterator iter = NMethodIterator();
4786 if(iter.next_alive()) {
4787 _first_nmethod = iter.method();
4788 }
4789 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4790 }
4791
4792 ~G1CodeCacheUnloadingTask() {
4793 CodeCache::verify_clean_inline_caches();
4794
4795 CodeCache::set_needs_cache_clean(false);
4796 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4797
4798 CodeCache::verify_icholder_relocations();
4799 }
4800
4801 private:
4802 void add_to_postponed_list(nmethod* nm) {
4803 nmethod* old;
4804 do {
4805 old = (nmethod*)_postponed_list;
4806 nm->set_unloading_next(old);
4807 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4808 }
4809
4810 void clean_nmethod(nmethod* nm) {
4811 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4812
4813 if (postponed) {
4814 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4815 add_to_postponed_list(nm);
4816 }
4817
4818 // Mark that this thread has been cleaned/unloaded.
4819 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4820 nm->set_unloading_clock(nmethod::global_unloading_clock());
4821 }
4822
4823 void clean_nmethod_postponed(nmethod* nm) {
4824 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4825 }
4826
4827 static const int MaxClaimNmethods = 16;
4828
4829 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4830 nmethod* first;
4831 NMethodIterator last;
4832
4833 do {
4834 *num_claimed_nmethods = 0;
4835
4836 first = (nmethod*)_claimed_nmethod;
4837 last = NMethodIterator(first);
4838
4839 if (first != NULL) {
4840
4841 for (int i = 0; i < MaxClaimNmethods; i++) {
4842 if (!last.next_alive()) {
4843 break;
4844 }
4845 claimed_nmethods[i] = last.method();
4846 (*num_claimed_nmethods)++;
4847 }
4848 }
4849
4850 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4851 }
4852
4853 nmethod* claim_postponed_nmethod() {
4854 nmethod* claim;
4855 nmethod* next;
4856
4857 do {
4858 claim = (nmethod*)_postponed_list;
4859 if (claim == NULL) {
4860 return NULL;
4861 }
4862
4863 next = claim->unloading_next();
4864
4865 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4866
4867 return claim;
4868 }
4869
4870 public:
4871 // Mark that we're done with the first pass of nmethod cleaning.
4872 void barrier_mark(uint worker_id) {
4873 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4874 _num_entered_barrier++;
4875 if (_num_entered_barrier == _num_workers) {
4876 ml.notify_all();
4877 }
4878 }
4879
4880 // See if we have to wait for the other workers to
4881 // finish their first-pass nmethod cleaning work.
4882 void barrier_wait(uint worker_id) {
4883 if (_num_entered_barrier < _num_workers) {
4884 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4885 while (_num_entered_barrier < _num_workers) {
4886 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4887 }
4888 }
4889 }
4890
4891 // Cleaning and unloading of nmethods. Some work has to be postponed
4892 // to the second pass, when we know which nmethods survive.
4893 void work_first_pass(uint worker_id) {
4894 // The first nmethods is claimed by the first worker.
4895 if (worker_id == 0 && _first_nmethod != NULL) {
4896 clean_nmethod(_first_nmethod);
4897 _first_nmethod = NULL;
4898 }
4899
4900 int num_claimed_nmethods;
4901 nmethod* claimed_nmethods[MaxClaimNmethods];
4902
4903 while (true) {
4904 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4905
4906 if (num_claimed_nmethods == 0) {
4907 break;
4908 }
4909
4910 for (int i = 0; i < num_claimed_nmethods; i++) {
4911 clean_nmethod(claimed_nmethods[i]);
4912 }
4913 }
4914 }
4915
4916 void work_second_pass(uint worker_id) {
4917 nmethod* nm;
4918 // Take care of postponed nmethods.
4919 while ((nm = claim_postponed_nmethod()) != NULL) {
4920 clean_nmethod_postponed(nm);
4921 }
4922 }
4923 };
4924
4925 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4926
4927 class G1KlassCleaningTask : public StackObj {
4928 BoolObjectClosure* _is_alive;
4929 volatile jint _clean_klass_tree_claimed;
4930 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4931
4932 public:
4933 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4934 _is_alive(is_alive),
4935 _clean_klass_tree_claimed(0),
4936 _klass_iterator() {
4937 }
4938
4939 private:
4940 bool claim_clean_klass_tree_task() {
4941 if (_clean_klass_tree_claimed) {
4942 return false;
4943 }
4944
4945 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4946 }
4947
4948 InstanceKlass* claim_next_klass() {
4949 Klass* klass;
4950 do {
4951 klass =_klass_iterator.next_klass();
4952 } while (klass != NULL && !klass->oop_is_instance());
4953
4954 return (InstanceKlass*)klass;
4955 }
4956
4957 public:
4958
4959 void clean_klass(InstanceKlass* ik) {
4960 ik->clean_implementors_list(_is_alive);
4961 ik->clean_method_data(_is_alive);
4962
4963 // G1 specific cleanup work that has
4964 // been moved here to be done in parallel.
4965 ik->clean_dependent_nmethods();
4966 }
4967
4968 void work() {
4969 ResourceMark rm;
4970
4971 // One worker will clean the subklass/sibling klass tree.
4972 if (claim_clean_klass_tree_task()) {
4973 Klass::clean_subklass_tree(_is_alive);
4974 }
4975
4976 // All workers will help cleaning the classes,
4977 InstanceKlass* klass;
4978 while ((klass = claim_next_klass()) != NULL) {
4979 clean_klass(klass);
4980 }
4981 }
4982 };
4983
4984 // To minimize the remark pause times, the tasks below are done in parallel.
4985 class G1ParallelCleaningTask : public AbstractGangTask {
4986 private:
4987 G1StringSymbolTableUnlinkTask _string_symbol_task;
4988 G1CodeCacheUnloadingTask _code_cache_task;
4989 G1KlassCleaningTask _klass_cleaning_task;
4990
4991 public:
4992 // The constructor is run in the VMThread.
4993 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4994 AbstractGangTask("Parallel Cleaning"),
4995 _string_symbol_task(is_alive, process_strings, process_symbols),
4996 _code_cache_task(num_workers, is_alive, unloading_occurred),
4997 _klass_cleaning_task(is_alive) {
4998 }
4999
5000 // The parallel work done by all worker threads.
5001 void work(uint worker_id) {
5002 // Do first pass of code cache cleaning.
5003 _code_cache_task.work_first_pass(worker_id);
5004
5005 // Let the threads mark that the first pass is done.
5006 _code_cache_task.barrier_mark(worker_id);
5007
5008 // Clean the Strings and Symbols.
5009 _string_symbol_task.work(worker_id);
5010
5011 // Wait for all workers to finish the first code cache cleaning pass.
5012 _code_cache_task.barrier_wait(worker_id);
5013
5014 // Do the second code cache cleaning work, which realize on
5015 // the liveness information gathered during the first pass.
5016 _code_cache_task.work_second_pass(worker_id);
5017
5018 // Clean all klasses that were not unloaded.
5019 _klass_cleaning_task.work();
5020 }
5021 };
5022
5023
5024 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5025 bool process_strings,
5026 bool process_symbols,
5027 bool class_unloading_occurred) {
5028 uint n_workers = workers()->active_workers();
5029
5030 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5031 n_workers, class_unloading_occurred);
5032 workers()->run_task(&g1_unlink_task);
5033 }
5034
5035 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5036 bool process_strings, bool process_symbols) {
5037 {
5038 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5039 workers()->run_task(&g1_unlink_task);
5040 }
5041
5042 if (G1StringDedup::is_enabled()) {
5043 G1StringDedup::unlink(is_alive);
5044 }
5045 }
5046
5047 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5048 private:
5049 DirtyCardQueueSet* _queue;
5050 public:
5051 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5052
5053 virtual void work(uint worker_id) {
5054 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5055 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5056
5057 RedirtyLoggedCardTableEntryClosure cl;
5058 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5059
5060 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5061 }
5062 };
5063
5064 void G1CollectedHeap::redirty_logged_cards() {
5065 double redirty_logged_cards_start = os::elapsedTime();
5066
5067 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5068 dirty_card_queue_set().reset_for_par_iteration();
5069 workers()->run_task(&redirty_task);
5070
5071 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5072 dcq.merge_bufferlists(&dirty_card_queue_set());
5073 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5074
5075 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5076 }
5077
5078 // Weak Reference Processing support
5079
5080 // An always "is_alive" closure that is used to preserve referents.
5081 // If the object is non-null then it's alive. Used in the preservation
5082 // of referent objects that are pointed to by reference objects
5083 // discovered by the CM ref processor.
5084 class G1AlwaysAliveClosure: public BoolObjectClosure {
5085 G1CollectedHeap* _g1;
5086 public:
5087 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5088 bool do_object_b(oop p) {
5089 if (p != NULL) {
5090 return true;
5091 }
5092 return false;
5093 }
5094 };
5095
5096 bool G1STWIsAliveClosure::do_object_b(oop p) {
5097 // An object is reachable if it is outside the collection set,
5098 // or is inside and copied.
5099 return !_g1->obj_in_cs(p) || p->is_forwarded();
5100 }
5101
5102 // Non Copying Keep Alive closure
5103 class G1KeepAliveClosure: public OopClosure {
5104 G1CollectedHeap* _g1;
5105 public:
5106 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5107 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5108 void do_oop(oop* p) {
5109 oop obj = *p;
5110 assert(obj != NULL, "the caller should have filtered out NULL values");
5111
5112 const InCSetState cset_state = _g1->in_cset_state(obj);
5113 if (!cset_state.is_in_cset_or_humongous()) {
5114 return;
5115 }
5116 if (cset_state.is_in_cset()) {
5117 assert( obj->is_forwarded(), "invariant" );
5118 *p = obj->forwardee();
5119 } else {
5120 assert(!obj->is_forwarded(), "invariant" );
5121 assert(cset_state.is_humongous(),
5122 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5123 _g1->set_humongous_is_live(obj);
5124 }
5125 }
5126 };
5127
5128 // Copying Keep Alive closure - can be called from both
5129 // serial and parallel code as long as different worker
5130 // threads utilize different G1ParScanThreadState instances
5131 // and different queues.
5132
5133 class G1CopyingKeepAliveClosure: public OopClosure {
5134 G1CollectedHeap* _g1h;
5135 OopClosure* _copy_non_heap_obj_cl;
5136 G1ParScanThreadState* _par_scan_state;
5137
5138 public:
5139 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5140 OopClosure* non_heap_obj_cl,
5141 G1ParScanThreadState* pss):
5142 _g1h(g1h),
5143 _copy_non_heap_obj_cl(non_heap_obj_cl),
5144 _par_scan_state(pss)
5145 {}
5146
5147 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5148 virtual void do_oop( oop* p) { do_oop_work(p); }
5149
5150 template <class T> void do_oop_work(T* p) {
5151 oop obj = oopDesc::load_decode_heap_oop(p);
5152
5153 if (_g1h->is_in_cset_or_humongous(obj)) {
5154 // If the referent object has been forwarded (either copied
5155 // to a new location or to itself in the event of an
5156 // evacuation failure) then we need to update the reference
5157 // field and, if both reference and referent are in the G1
5158 // heap, update the RSet for the referent.
5159 //
5160 // If the referent has not been forwarded then we have to keep
5161 // it alive by policy. Therefore we have copy the referent.
5162 //
5163 // If the reference field is in the G1 heap then we can push
5164 // on the PSS queue. When the queue is drained (after each
5165 // phase of reference processing) the object and it's followers
5166 // will be copied, the reference field set to point to the
5167 // new location, and the RSet updated. Otherwise we need to
5168 // use the the non-heap or metadata closures directly to copy
5169 // the referent object and update the pointer, while avoiding
5170 // updating the RSet.
5171
5172 if (_g1h->is_in_g1_reserved(p)) {
5173 _par_scan_state->push_on_queue(p);
5174 } else {
5175 assert(!Metaspace::contains((const void*)p),
5176 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5177 _copy_non_heap_obj_cl->do_oop(p);
5178 }
5179 }
5180 }
5181 };
5182
5183 // Serial drain queue closure. Called as the 'complete_gc'
5184 // closure for each discovered list in some of the
5185 // reference processing phases.
5186
5187 class G1STWDrainQueueClosure: public VoidClosure {
5188 protected:
5189 G1CollectedHeap* _g1h;
5190 G1ParScanThreadState* _par_scan_state;
5191
5192 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5193
5194 public:
5195 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5196 _g1h(g1h),
5197 _par_scan_state(pss)
5198 { }
5199
5200 void do_void() {
5201 G1ParScanThreadState* const pss = par_scan_state();
5202 pss->trim_queue();
5203 }
5204 };
5205
5206 // Parallel Reference Processing closures
5207
5208 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5209 // processing during G1 evacuation pauses.
5210
5211 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5212 private:
5213 G1CollectedHeap* _g1h;
5214 RefToScanQueueSet* _queues;
5215 FlexibleWorkGang* _workers;
5216 uint _active_workers;
5217
5218 public:
5219 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5220 FlexibleWorkGang* workers,
5221 RefToScanQueueSet *task_queues,
5222 uint n_workers) :
5223 _g1h(g1h),
5224 _queues(task_queues),
5225 _workers(workers),
5226 _active_workers(n_workers)
5227 {
5228 assert(n_workers > 0, "shouldn't call this otherwise");
5229 }
5230
5231 // Executes the given task using concurrent marking worker threads.
5232 virtual void execute(ProcessTask& task);
5233 virtual void execute(EnqueueTask& task);
5234 };
5235
5236 // Gang task for possibly parallel reference processing
5237
5238 class G1STWRefProcTaskProxy: public AbstractGangTask {
5239 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5240 ProcessTask& _proc_task;
5241 G1CollectedHeap* _g1h;
5242 RefToScanQueueSet *_task_queues;
5243 ParallelTaskTerminator* _terminator;
5244
5245 public:
5246 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5247 G1CollectedHeap* g1h,
5248 RefToScanQueueSet *task_queues,
5249 ParallelTaskTerminator* terminator) :
5250 AbstractGangTask("Process reference objects in parallel"),
5251 _proc_task(proc_task),
5252 _g1h(g1h),
5253 _task_queues(task_queues),
5254 _terminator(terminator)
5255 {}
5256
5257 virtual void work(uint worker_id) {
5258 // The reference processing task executed by a single worker.
5259 ResourceMark rm;
5260 HandleMark hm;
5261
5262 G1STWIsAliveClosure is_alive(_g1h);
5263
5264 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5265 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5266
5267 pss.set_evac_failure_closure(&evac_failure_cl);
5268
5269 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5270
5271 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5272
5273 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5274
5275 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5276 // We also need to mark copied objects.
5277 copy_non_heap_cl = ©_mark_non_heap_cl;
5278 }
5279
5280 // Keep alive closure.
5281 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5282
5283 // Complete GC closure
5284 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5285
5286 // Call the reference processing task's work routine.
5287 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5288
5289 // Note we cannot assert that the refs array is empty here as not all
5290 // of the processing tasks (specifically phase2 - pp2_work) execute
5291 // the complete_gc closure (which ordinarily would drain the queue) so
5292 // the queue may not be empty.
5293 }
5294 };
5295
5296 // Driver routine for parallel reference processing.
5297 // Creates an instance of the ref processing gang
5298 // task and has the worker threads execute it.
5299 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5300 assert(_workers != NULL, "Need parallel worker threads.");
5301
5302 ParallelTaskTerminator terminator(_active_workers, _queues);
5303 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5304
5305 _workers->run_task(&proc_task_proxy);
5306 }
5307
5308 // Gang task for parallel reference enqueueing.
5309
5310 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5311 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5312 EnqueueTask& _enq_task;
5313
5314 public:
5315 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5316 AbstractGangTask("Enqueue reference objects in parallel"),
5317 _enq_task(enq_task)
5318 { }
5319
5320 virtual void work(uint worker_id) {
5321 _enq_task.work(worker_id);
5322 }
5323 };
5324
5325 // Driver routine for parallel reference enqueueing.
5326 // Creates an instance of the ref enqueueing gang
5327 // task and has the worker threads execute it.
5328
5329 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5330 assert(_workers != NULL, "Need parallel worker threads.");
5331
5332 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5333
5334 _workers->run_task(&enq_task_proxy);
5335 }
5336
5337 // End of weak reference support closures
5338
5339 // Abstract task used to preserve (i.e. copy) any referent objects
5340 // that are in the collection set and are pointed to by reference
5341 // objects discovered by the CM ref processor.
5342
5343 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5344 protected:
5345 G1CollectedHeap* _g1h;
5346 RefToScanQueueSet *_queues;
5347 ParallelTaskTerminator _terminator;
5348 uint _n_workers;
5349
5350 public:
5351 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5352 AbstractGangTask("ParPreserveCMReferents"),
5353 _g1h(g1h),
5354 _queues(task_queues),
5355 _terminator(workers, _queues),
5356 _n_workers(workers)
5357 { }
5358
5359 void work(uint worker_id) {
5360 ResourceMark rm;
5361 HandleMark hm;
5362
5363 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5364 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5365
5366 pss.set_evac_failure_closure(&evac_failure_cl);
5367
5368 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5369
5370 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5371
5372 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5373
5374 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5375
5376 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5377 // We also need to mark copied objects.
5378 copy_non_heap_cl = ©_mark_non_heap_cl;
5379 }
5380
5381 // Is alive closure
5382 G1AlwaysAliveClosure always_alive(_g1h);
5383
5384 // Copying keep alive closure. Applied to referent objects that need
5385 // to be copied.
5386 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5387
5388 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5389
5390 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5391 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5392
5393 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5394 // So this must be true - but assert just in case someone decides to
5395 // change the worker ids.
5396 assert(worker_id < limit, "sanity");
5397 assert(!rp->discovery_is_atomic(), "check this code");
5398
5399 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5400 for (uint idx = worker_id; idx < limit; idx += stride) {
5401 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5402
5403 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5404 while (iter.has_next()) {
5405 // Since discovery is not atomic for the CM ref processor, we
5406 // can see some null referent objects.
5407 iter.load_ptrs(DEBUG_ONLY(true));
5408 oop ref = iter.obj();
5409
5410 // This will filter nulls.
5411 if (iter.is_referent_alive()) {
5412 iter.make_referent_alive();
5413 }
5414 iter.move_to_next();
5415 }
5416 }
5417
5418 // Drain the queue - which may cause stealing
5419 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5420 drain_queue.do_void();
5421 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5422 assert(pss.queue_is_empty(), "should be");
5423 }
5424 };
5425
5426 // Weak Reference processing during an evacuation pause (part 1).
5427 void G1CollectedHeap::process_discovered_references() {
5428 double ref_proc_start = os::elapsedTime();
5429
5430 ReferenceProcessor* rp = _ref_processor_stw;
5431 assert(rp->discovery_enabled(), "should have been enabled");
5432
5433 // Any reference objects, in the collection set, that were 'discovered'
5434 // by the CM ref processor should have already been copied (either by
5435 // applying the external root copy closure to the discovered lists, or
5436 // by following an RSet entry).
5437 //
5438 // But some of the referents, that are in the collection set, that these
5439 // reference objects point to may not have been copied: the STW ref
5440 // processor would have seen that the reference object had already
5441 // been 'discovered' and would have skipped discovering the reference,
5442 // but would not have treated the reference object as a regular oop.
5443 // As a result the copy closure would not have been applied to the
5444 // referent object.
5445 //
5446 // We need to explicitly copy these referent objects - the references
5447 // will be processed at the end of remarking.
5448 //
5449 // We also need to do this copying before we process the reference
5450 // objects discovered by the STW ref processor in case one of these
5451 // referents points to another object which is also referenced by an
5452 // object discovered by the STW ref processor.
5453
5454 uint no_of_gc_workers = workers()->active_workers();
5455
5456 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5457 no_of_gc_workers,
5458 _task_queues);
5459
5460 workers()->run_task(&keep_cm_referents);
5461
5462 // Closure to test whether a referent is alive.
5463 G1STWIsAliveClosure is_alive(this);
5464
5465 // Even when parallel reference processing is enabled, the processing
5466 // of JNI refs is serial and performed serially by the current thread
5467 // rather than by a worker. The following PSS will be used for processing
5468 // JNI refs.
5469
5470 // Use only a single queue for this PSS.
5471 G1ParScanThreadState pss(this, 0, NULL);
5472
5473 // We do not embed a reference processor in the copying/scanning
5474 // closures while we're actually processing the discovered
5475 // reference objects.
5476 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5477
5478 pss.set_evac_failure_closure(&evac_failure_cl);
5479
5480 assert(pss.queue_is_empty(), "pre-condition");
5481
5482 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5483
5484 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5485
5486 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5487
5488 if (g1_policy()->during_initial_mark_pause()) {
5489 // We also need to mark copied objects.
5490 copy_non_heap_cl = ©_mark_non_heap_cl;
5491 }
5492
5493 // Keep alive closure.
5494 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5495
5496 // Serial Complete GC closure
5497 G1STWDrainQueueClosure drain_queue(this, &pss);
5498
5499 // Setup the soft refs policy...
5500 rp->setup_policy(false);
5501
5502 ReferenceProcessorStats stats;
5503 if (!rp->processing_is_mt()) {
5504 // Serial reference processing...
5505 stats = rp->process_discovered_references(&is_alive,
5506 &keep_alive,
5507 &drain_queue,
5508 NULL,
5509 _gc_timer_stw,
5510 _gc_tracer_stw->gc_id());
5511 } else {
5512 // Parallel reference processing
5513 assert(rp->num_q() == no_of_gc_workers, "sanity");
5514 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5515
5516 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5517 stats = rp->process_discovered_references(&is_alive,
5518 &keep_alive,
5519 &drain_queue,
5520 &par_task_executor,
5521 _gc_timer_stw,
5522 _gc_tracer_stw->gc_id());
5523 }
5524
5525 _gc_tracer_stw->report_gc_reference_stats(stats);
5526
5527 // We have completed copying any necessary live referent objects.
5528 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5529
5530 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5531 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5532 }
5533
5534 // Weak Reference processing during an evacuation pause (part 2).
5535 void G1CollectedHeap::enqueue_discovered_references() {
5536 double ref_enq_start = os::elapsedTime();
5537
5538 ReferenceProcessor* rp = _ref_processor_stw;
5539 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5540
5541 // Now enqueue any remaining on the discovered lists on to
5542 // the pending list.
5543 if (!rp->processing_is_mt()) {
5544 // Serial reference processing...
5545 rp->enqueue_discovered_references();
5546 } else {
5547 // Parallel reference enqueueing
5548
5549 uint n_workers = workers()->active_workers();
5550
5551 assert(rp->num_q() == n_workers, "sanity");
5552 assert(n_workers <= rp->max_num_q(), "sanity");
5553
5554 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5555 rp->enqueue_discovered_references(&par_task_executor);
5556 }
5557
5558 rp->verify_no_references_recorded();
5559 assert(!rp->discovery_enabled(), "should have been disabled");
5560
5561 // FIXME
5562 // CM's reference processing also cleans up the string and symbol tables.
5563 // Should we do that here also? We could, but it is a serial operation
5564 // and could significantly increase the pause time.
5565
5566 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5567 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5568 }
5569
5570 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5571 _expand_heap_after_alloc_failure = true;
5572 _evacuation_failed = false;
5573
5574 // Should G1EvacuationFailureALot be in effect for this GC?
5575 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5576
5577 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5578
5579 // Disable the hot card cache.
5580 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5581 hot_card_cache->reset_hot_cache_claimed_index();
5582 hot_card_cache->set_use_cache(false);
5583
5584 const uint n_workers = workers()->active_workers();
5585
5586 init_for_evac_failure(NULL);
5587
5588 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5589 double start_par_time_sec = os::elapsedTime();
5590 double end_par_time_sec;
5591
5592 {
5593 G1RootProcessor root_processor(this, n_workers);
5594 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5595 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5596 if (g1_policy()->during_initial_mark_pause()) {
5597 ClassLoaderDataGraph::clear_claimed_marks();
5598 }
5599
5600 // The individual threads will set their evac-failure closures.
5601 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5602
5603 workers()->run_task(&g1_par_task);
5604 end_par_time_sec = os::elapsedTime();
5605
5606 // Closing the inner scope will execute the destructor
5607 // for the G1RootProcessor object. We record the current
5608 // elapsed time before closing the scope so that time
5609 // taken for the destructor is NOT included in the
5610 // reported parallel time.
5611 }
5612
5613 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5614
5615 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5616 phase_times->record_par_time(par_time_ms);
5617
5618 double code_root_fixup_time_ms =
5619 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5620 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5621
5622 // Process any discovered reference objects - we have
5623 // to do this _before_ we retire the GC alloc regions
5624 // as we may have to copy some 'reachable' referent
5625 // objects (and their reachable sub-graphs) that were
5626 // not copied during the pause.
5627 process_discovered_references();
5628
5629 if (G1StringDedup::is_enabled()) {
5630 double fixup_start = os::elapsedTime();
5631
5632 G1STWIsAliveClosure is_alive(this);
5633 G1KeepAliveClosure keep_alive(this);
5634 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5635
5636 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5637 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5638 }
5639
5640 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5641 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5642
5643 // Reset and re-enable the hot card cache.
5644 // Note the counts for the cards in the regions in the
5645 // collection set are reset when the collection set is freed.
5646 hot_card_cache->reset_hot_cache();
5647 hot_card_cache->set_use_cache(true);
5648
5649 purge_code_root_memory();
5650
5651 finalize_for_evac_failure();
5652
5653 if (evacuation_failed()) {
5654 remove_self_forwarding_pointers();
5655
5656 // Reset the G1EvacuationFailureALot counters and flags
5657 // Note: the values are reset only when an actual
5658 // evacuation failure occurs.
5659 NOT_PRODUCT(reset_evacuation_should_fail();)
5660 }
5661
5662 // Enqueue any remaining references remaining on the STW
5663 // reference processor's discovered lists. We need to do
5664 // this after the card table is cleaned (and verified) as
5665 // the act of enqueueing entries on to the pending list
5666 // will log these updates (and dirty their associated
5667 // cards). We need these updates logged to update any
5668 // RSets.
5669 enqueue_discovered_references();
5670
5671 redirty_logged_cards();
5672 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5673 }
5674
5675 void G1CollectedHeap::free_region(HeapRegion* hr,
5676 FreeRegionList* free_list,
5677 bool par,
5678 bool locked) {
5679 assert(!hr->is_free(), "the region should not be free");
5680 assert(!hr->is_empty(), "the region should not be empty");
5681 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5682 assert(free_list != NULL, "pre-condition");
5683
5684 if (G1VerifyBitmaps) {
5685 MemRegion mr(hr->bottom(), hr->end());
5686 concurrent_mark()->clearRangePrevBitmap(mr);
5687 }
5688
5689 // Clear the card counts for this region.
5690 // Note: we only need to do this if the region is not young
5691 // (since we don't refine cards in young regions).
5692 if (!hr->is_young()) {
5693 _cg1r->hot_card_cache()->reset_card_counts(hr);
5694 }
5695 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5696 free_list->add_ordered(hr);
5697 }
5698
5699 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5700 FreeRegionList* free_list,
5701 bool par) {
5702 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5703 assert(free_list != NULL, "pre-condition");
5704
5705 size_t hr_capacity = hr->capacity();
5706 // We need to read this before we make the region non-humongous,
5707 // otherwise the information will be gone.
5708 uint last_index = hr->last_hc_index();
5709 hr->clear_humongous();
5710 free_region(hr, free_list, par);
5711
5712 uint i = hr->hrm_index() + 1;
5713 while (i < last_index) {
5714 HeapRegion* curr_hr = region_at(i);
5715 assert(curr_hr->is_continues_humongous(), "invariant");
5716 curr_hr->clear_humongous();
5717 free_region(curr_hr, free_list, par);
5718 i += 1;
5719 }
5720 }
5721
5722 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5723 const HeapRegionSetCount& humongous_regions_removed) {
5724 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5725 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5726 _old_set.bulk_remove(old_regions_removed);
5727 _humongous_set.bulk_remove(humongous_regions_removed);
5728 }
5729
5730 }
5731
5732 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5733 assert(list != NULL, "list can't be null");
5734 if (!list->is_empty()) {
5735 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5736 _hrm.insert_list_into_free_list(list);
5737 }
5738 }
5739
5740 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5741 _allocator->decrease_used(bytes);
5742 }
5743
5744 class G1ParCleanupCTTask : public AbstractGangTask {
5745 G1SATBCardTableModRefBS* _ct_bs;
5746 G1CollectedHeap* _g1h;
5747 HeapRegion* volatile _su_head;
5748 public:
5749 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5750 G1CollectedHeap* g1h) :
5751 AbstractGangTask("G1 Par Cleanup CT Task"),
5752 _ct_bs(ct_bs), _g1h(g1h) { }
5753
5754 void work(uint worker_id) {
5755 HeapRegion* r;
5756 while (r = _g1h->pop_dirty_cards_region()) {
5757 clear_cards(r);
5758 }
5759 }
5760
5761 void clear_cards(HeapRegion* r) {
5762 // Cards of the survivors should have already been dirtied.
5763 if (!r->is_survivor()) {
5764 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5765 }
5766 }
5767 };
5768
5769 #ifndef PRODUCT
5770 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5771 G1CollectedHeap* _g1h;
5772 G1SATBCardTableModRefBS* _ct_bs;
5773 public:
5774 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5775 : _g1h(g1h), _ct_bs(ct_bs) { }
5776 virtual bool doHeapRegion(HeapRegion* r) {
5777 if (r->is_survivor()) {
5778 _g1h->verify_dirty_region(r);
5779 } else {
5780 _g1h->verify_not_dirty_region(r);
5781 }
5782 return false;
5783 }
5784 };
5785
5786 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5787 // All of the region should be clean.
5788 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5789 MemRegion mr(hr->bottom(), hr->end());
5790 ct_bs->verify_not_dirty_region(mr);
5791 }
5792
5793 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5794 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5795 // dirty allocated blocks as they allocate them. The thread that
5796 // retires each region and replaces it with a new one will do a
5797 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5798 // not dirty that area (one less thing to have to do while holding
5799 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5800 // is dirty.
5801 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5802 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5803 if (hr->is_young()) {
5804 ct_bs->verify_g1_young_region(mr);
5805 } else {
5806 ct_bs->verify_dirty_region(mr);
5807 }
5808 }
5809
5810 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5811 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5812 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5813 verify_dirty_region(hr);
5814 }
5815 }
5816
5817 void G1CollectedHeap::verify_dirty_young_regions() {
5818 verify_dirty_young_list(_young_list->first_region());
5819 }
5820
5821 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5822 HeapWord* tams, HeapWord* end) {
5823 guarantee(tams <= end,
5824 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5825 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5826 if (result < end) {
5827 gclog_or_tty->cr();
5828 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5829 bitmap_name, p2i(result));
5830 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5831 bitmap_name, p2i(tams), p2i(end));
5832 return false;
5833 }
5834 return true;
5835 }
5836
5837 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5838 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5839 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5840
5841 HeapWord* bottom = hr->bottom();
5842 HeapWord* ptams = hr->prev_top_at_mark_start();
5843 HeapWord* ntams = hr->next_top_at_mark_start();
5844 HeapWord* end = hr->end();
5845
5846 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5847
5848 bool res_n = true;
5849 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5850 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5851 // if we happen to be in that state.
5852 if (mark_in_progress() || !_cmThread->in_progress()) {
5853 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5854 }
5855 if (!res_p || !res_n) {
5856 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5857 HR_FORMAT_PARAMS(hr));
5858 gclog_or_tty->print_cr("#### Caller: %s", caller);
5859 return false;
5860 }
5861 return true;
5862 }
5863
5864 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5865 if (!G1VerifyBitmaps) return;
5866
5867 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5868 }
5869
5870 class G1VerifyBitmapClosure : public HeapRegionClosure {
5871 private:
5872 const char* _caller;
5873 G1CollectedHeap* _g1h;
5874 bool _failures;
5875
5876 public:
5877 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5878 _caller(caller), _g1h(g1h), _failures(false) { }
5879
5880 bool failures() { return _failures; }
5881
5882 virtual bool doHeapRegion(HeapRegion* hr) {
5883 if (hr->is_continues_humongous()) return false;
5884
5885 bool result = _g1h->verify_bitmaps(_caller, hr);
5886 if (!result) {
5887 _failures = true;
5888 }
5889 return false;
5890 }
5891 };
5892
5893 void G1CollectedHeap::check_bitmaps(const char* caller) {
5894 if (!G1VerifyBitmaps) return;
5895
5896 G1VerifyBitmapClosure cl(caller, this);
5897 heap_region_iterate(&cl);
5898 guarantee(!cl.failures(), "bitmap verification");
5899 }
5900
5901 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5902 private:
5903 bool _failures;
5904 public:
5905 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5906
5907 virtual bool doHeapRegion(HeapRegion* hr) {
5908 uint i = hr->hrm_index();
5909 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5910 if (hr->is_humongous()) {
5911 if (hr->in_collection_set()) {
5912 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5913 _failures = true;
5914 return true;
5915 }
5916 if (cset_state.is_in_cset()) {
5917 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5918 _failures = true;
5919 return true;
5920 }
5921 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5922 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5923 _failures = true;
5924 return true;
5925 }
5926 } else {
5927 if (cset_state.is_humongous()) {
5928 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5929 _failures = true;
5930 return true;
5931 }
5932 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5933 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5934 hr->in_collection_set(), cset_state.value(), i);
5935 _failures = true;
5936 return true;
5937 }
5938 if (cset_state.is_in_cset()) {
5939 if (hr->is_young() != (cset_state.is_young())) {
5940 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5941 hr->is_young(), cset_state.value(), i);
5942 _failures = true;
5943 return true;
5944 }
5945 if (hr->is_old() != (cset_state.is_old())) {
5946 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5947 hr->is_old(), cset_state.value(), i);
5948 _failures = true;
5949 return true;
5950 }
5951 }
5952 }
5953 return false;
5954 }
5955
5956 bool failures() const { return _failures; }
5957 };
5958
5959 bool G1CollectedHeap::check_cset_fast_test() {
5960 G1CheckCSetFastTableClosure cl;
5961 _hrm.iterate(&cl);
5962 return !cl.failures();
5963 }
5964 #endif // PRODUCT
5965
5966 void G1CollectedHeap::cleanUpCardTable() {
5967 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5968 double start = os::elapsedTime();
5969
5970 {
5971 // Iterate over the dirty cards region list.
5972 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5973
5974 workers()->run_task(&cleanup_task);
5975 #ifndef PRODUCT
5976 if (G1VerifyCTCleanup || VerifyAfterGC) {
5977 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5978 heap_region_iterate(&cleanup_verifier);
5979 }
5980 #endif
5981 }
5982
5983 double elapsed = os::elapsedTime() - start;
5984 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5985 }
5986
5987 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5988 size_t pre_used = 0;
5989 FreeRegionList local_free_list("Local List for CSet Freeing");
5990
5991 double young_time_ms = 0.0;
5992 double non_young_time_ms = 0.0;
5993
5994 // Since the collection set is a superset of the the young list,
5995 // all we need to do to clear the young list is clear its
5996 // head and length, and unlink any young regions in the code below
5997 _young_list->clear();
5998
5999 G1CollectorPolicy* policy = g1_policy();
6000
6001 double start_sec = os::elapsedTime();
6002 bool non_young = true;
6003
6004 HeapRegion* cur = cs_head;
6005 int age_bound = -1;
6006 size_t rs_lengths = 0;
6007
6008 while (cur != NULL) {
6009 assert(!is_on_master_free_list(cur), "sanity");
6010 if (non_young) {
6011 if (cur->is_young()) {
6012 double end_sec = os::elapsedTime();
6013 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6014 non_young_time_ms += elapsed_ms;
6015
6016 start_sec = os::elapsedTime();
6017 non_young = false;
6018 }
6019 } else {
6020 if (!cur->is_young()) {
6021 double end_sec = os::elapsedTime();
6022 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6023 young_time_ms += elapsed_ms;
6024
6025 start_sec = os::elapsedTime();
6026 non_young = true;
6027 }
6028 }
6029
6030 rs_lengths += cur->rem_set()->occupied_locked();
6031
6032 HeapRegion* next = cur->next_in_collection_set();
6033 assert(cur->in_collection_set(), "bad CS");
6034 cur->set_next_in_collection_set(NULL);
6035 clear_in_cset(cur);
6036
6037 if (cur->is_young()) {
6038 int index = cur->young_index_in_cset();
6039 assert(index != -1, "invariant");
6040 assert((uint) index < policy->young_cset_region_length(), "invariant");
6041 size_t words_survived = _surviving_young_words[index];
6042 cur->record_surv_words_in_group(words_survived);
6043
6044 // At this point the we have 'popped' cur from the collection set
6045 // (linked via next_in_collection_set()) but it is still in the
6046 // young list (linked via next_young_region()). Clear the
6047 // _next_young_region field.
6048 cur->set_next_young_region(NULL);
6049 } else {
6050 int index = cur->young_index_in_cset();
6051 assert(index == -1, "invariant");
6052 }
6053
6054 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6055 (!cur->is_young() && cur->young_index_in_cset() == -1),
6056 "invariant" );
6057
6058 if (!cur->evacuation_failed()) {
6059 MemRegion used_mr = cur->used_region();
6060
6061 // And the region is empty.
6062 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6063 pre_used += cur->used();
6064 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6065 } else {
6066 cur->uninstall_surv_rate_group();
6067 if (cur->is_young()) {
6068 cur->set_young_index_in_cset(-1);
6069 }
6070 cur->set_evacuation_failed(false);
6071 // The region is now considered to be old.
6072 cur->set_old();
6073 _old_set.add(cur);
6074 evacuation_info.increment_collectionset_used_after(cur->used());
6075 }
6076 cur = next;
6077 }
6078
6079 evacuation_info.set_regions_freed(local_free_list.length());
6080 policy->record_max_rs_lengths(rs_lengths);
6081 policy->cset_regions_freed();
6082
6083 double end_sec = os::elapsedTime();
6084 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6085
6086 if (non_young) {
6087 non_young_time_ms += elapsed_ms;
6088 } else {
6089 young_time_ms += elapsed_ms;
6090 }
6091
6092 prepend_to_freelist(&local_free_list);
6093 decrement_summary_bytes(pre_used);
6094 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6095 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6096 }
6097
6098 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6099 private:
6100 FreeRegionList* _free_region_list;
6101 HeapRegionSet* _proxy_set;
6102 HeapRegionSetCount _humongous_regions_removed;
6103 size_t _freed_bytes;
6104 public:
6105
6106 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6107 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6108 }
6109
6110 virtual bool doHeapRegion(HeapRegion* r) {
6111 if (!r->is_starts_humongous()) {
6112 return false;
6113 }
6114
6115 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6116
6117 oop obj = (oop)r->bottom();
6118 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6119
6120 // The following checks whether the humongous object is live are sufficient.
6121 // The main additional check (in addition to having a reference from the roots
6122 // or the young gen) is whether the humongous object has a remembered set entry.
6123 //
6124 // A humongous object cannot be live if there is no remembered set for it
6125 // because:
6126 // - there can be no references from within humongous starts regions referencing
6127 // the object because we never allocate other objects into them.
6128 // (I.e. there are no intra-region references that may be missed by the
6129 // remembered set)
6130 // - as soon there is a remembered set entry to the humongous starts region
6131 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6132 // until the end of a concurrent mark.
6133 //
6134 // It is not required to check whether the object has been found dead by marking
6135 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6136 // all objects allocated during that time are considered live.
6137 // SATB marking is even more conservative than the remembered set.
6138 // So if at this point in the collection there is no remembered set entry,
6139 // nobody has a reference to it.
6140 // At the start of collection we flush all refinement logs, and remembered sets
6141 // are completely up-to-date wrt to references to the humongous object.
6142 //
6143 // Other implementation considerations:
6144 // - never consider object arrays at this time because they would pose
6145 // considerable effort for cleaning up the the remembered sets. This is
6146 // required because stale remembered sets might reference locations that
6147 // are currently allocated into.
6148 uint region_idx = r->hrm_index();
6149 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6150 !r->rem_set()->is_empty()) {
6151
6152 if (G1TraceEagerReclaimHumongousObjects) {
6153 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6154 region_idx,
6155 (size_t)obj->size() * HeapWordSize,
6156 p2i(r->bottom()),
6157 r->region_num(),
6158 r->rem_set()->occupied(),
6159 r->rem_set()->strong_code_roots_list_length(),
6160 next_bitmap->isMarked(r->bottom()),
6161 g1h->is_humongous_reclaim_candidate(region_idx),
6162 obj->is_typeArray()
6163 );
6164 }
6165
6166 return false;
6167 }
6168
6169 guarantee(obj->is_typeArray(),
6170 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6171 PTR_FORMAT " is not.",
6172 p2i(r->bottom())));
6173
6174 if (G1TraceEagerReclaimHumongousObjects) {
6175 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6176 region_idx,
6177 (size_t)obj->size() * HeapWordSize,
6178 p2i(r->bottom()),
6179 r->region_num(),
6180 r->rem_set()->occupied(),
6181 r->rem_set()->strong_code_roots_list_length(),
6182 next_bitmap->isMarked(r->bottom()),
6183 g1h->is_humongous_reclaim_candidate(region_idx),
6184 obj->is_typeArray()
6185 );
6186 }
6187 // Need to clear mark bit of the humongous object if already set.
6188 if (next_bitmap->isMarked(r->bottom())) {
6189 next_bitmap->clear(r->bottom());
6190 }
6191 _freed_bytes += r->used();
6192 r->set_containing_set(NULL);
6193 _humongous_regions_removed.increment(1u, r->capacity());
6194 g1h->free_humongous_region(r, _free_region_list, false);
6195
6196 return false;
6197 }
6198
6199 HeapRegionSetCount& humongous_free_count() {
6200 return _humongous_regions_removed;
6201 }
6202
6203 size_t bytes_freed() const {
6204 return _freed_bytes;
6205 }
6206
6207 size_t humongous_reclaimed() const {
6208 return _humongous_regions_removed.length();
6209 }
6210 };
6211
6212 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6213 assert_at_safepoint(true);
6214
6215 if (!G1EagerReclaimHumongousObjects ||
6216 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6217 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6218 return;
6219 }
6220
6221 double start_time = os::elapsedTime();
6222
6223 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6224
6225 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6226 heap_region_iterate(&cl);
6227
6228 HeapRegionSetCount empty_set;
6229 remove_from_old_sets(empty_set, cl.humongous_free_count());
6230
6231 G1HRPrinter* hrp = hr_printer();
6232 if (hrp->is_active()) {
6233 FreeRegionListIterator iter(&local_cleanup_list);
6234 while (iter.more_available()) {
6235 HeapRegion* hr = iter.get_next();
6236 hrp->cleanup(hr);
6237 }
6238 }
6239
6240 prepend_to_freelist(&local_cleanup_list);
6241 decrement_summary_bytes(cl.bytes_freed());
6242
6243 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6244 cl.humongous_reclaimed());
6245 }
6246
6247 // This routine is similar to the above but does not record
6248 // any policy statistics or update free lists; we are abandoning
6249 // the current incremental collection set in preparation of a
6250 // full collection. After the full GC we will start to build up
6251 // the incremental collection set again.
6252 // This is only called when we're doing a full collection
6253 // and is immediately followed by the tearing down of the young list.
6254
6255 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6256 HeapRegion* cur = cs_head;
6257
6258 while (cur != NULL) {
6259 HeapRegion* next = cur->next_in_collection_set();
6260 assert(cur->in_collection_set(), "bad CS");
6261 cur->set_next_in_collection_set(NULL);
6262 clear_in_cset(cur);
6263 cur->set_young_index_in_cset(-1);
6264 cur = next;
6265 }
6266 }
6267
6268 void G1CollectedHeap::set_free_regions_coming() {
6269 if (G1ConcRegionFreeingVerbose) {
6270 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6271 "setting free regions coming");
6272 }
6273
6274 assert(!free_regions_coming(), "pre-condition");
6275 _free_regions_coming = true;
6276 }
6277
6278 void G1CollectedHeap::reset_free_regions_coming() {
6279 assert(free_regions_coming(), "pre-condition");
6280
6281 {
6282 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6283 _free_regions_coming = false;
6284 SecondaryFreeList_lock->notify_all();
6285 }
6286
6287 if (G1ConcRegionFreeingVerbose) {
6288 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6289 "reset free regions coming");
6290 }
6291 }
6292
6293 void G1CollectedHeap::wait_while_free_regions_coming() {
6294 // Most of the time we won't have to wait, so let's do a quick test
6295 // first before we take the lock.
6296 if (!free_regions_coming()) {
6297 return;
6298 }
6299
6300 if (G1ConcRegionFreeingVerbose) {
6301 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6302 "waiting for free regions");
6303 }
6304
6305 {
6306 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6307 while (free_regions_coming()) {
6308 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6309 }
6310 }
6311
6312 if (G1ConcRegionFreeingVerbose) {
6313 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6314 "done waiting for free regions");
6315 }
6316 }
6317
6318 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6319 _young_list->push_region(hr);
6320 }
6321
6322 class NoYoungRegionsClosure: public HeapRegionClosure {
6323 private:
6324 bool _success;
6325 public:
6326 NoYoungRegionsClosure() : _success(true) { }
6327 bool doHeapRegion(HeapRegion* r) {
6328 if (r->is_young()) {
6329 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6330 p2i(r->bottom()), p2i(r->end()));
6331 _success = false;
6332 }
6333 return false;
6334 }
6335 bool success() { return _success; }
6336 };
6337
6338 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6339 bool ret = _young_list->check_list_empty(check_sample);
6340
6341 if (check_heap) {
6342 NoYoungRegionsClosure closure;
6343 heap_region_iterate(&closure);
6344 ret = ret && closure.success();
6345 }
6346
6347 return ret;
6348 }
6349
6350 class TearDownRegionSetsClosure : public HeapRegionClosure {
6351 private:
6352 HeapRegionSet *_old_set;
6353
6354 public:
6355 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6356
6357 bool doHeapRegion(HeapRegion* r) {
6358 if (r->is_old()) {
6359 _old_set->remove(r);
6360 } else {
6361 // We ignore free regions, we'll empty the free list afterwards.
6362 // We ignore young regions, we'll empty the young list afterwards.
6363 // We ignore humongous regions, we're not tearing down the
6364 // humongous regions set.
6365 // We ignore archive regions.
6366 assert(r->is_free() || r->is_young() || r->is_humongous() || r->is_archive(),
6367 "it cannot be another type");
6368 }
6369 return false;
6370 }
6371
6372 ~TearDownRegionSetsClosure() {
6373 assert(_old_set->is_empty(), "post-condition");
6374 }
6375 };
6376
6377 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6378 assert_at_safepoint(true /* should_be_vm_thread */);
6379
6380 if (!free_list_only) {
6381 TearDownRegionSetsClosure cl(&_old_set);
6382 heap_region_iterate(&cl);
6383
6384 // Note that emptying the _young_list is postponed and instead done as
6385 // the first step when rebuilding the regions sets again. The reason for
6386 // this is that during a full GC string deduplication needs to know if
6387 // a collected region was young or old when the full GC was initiated.
6388 }
6389 _hrm.remove_all_free_regions();
6390 }
6391
6392 class RebuildRegionSetsClosure : public HeapRegionClosure {
6393 private:
6394 bool _free_list_only;
6395 HeapRegionSet* _old_set;
6396 HeapRegionManager* _hrm;
6397 size_t _total_used;
6398
6399 public:
6400 RebuildRegionSetsClosure(bool free_list_only,
6401 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6402 _free_list_only(free_list_only),
6403 _old_set(old_set), _hrm(hrm), _total_used(0) {
6404 assert(_hrm->num_free_regions() == 0, "pre-condition");
6405 if (!free_list_only) {
6406 assert(_old_set->is_empty(), "pre-condition");
6407 }
6408 }
6409
6410 bool doHeapRegion(HeapRegion* r) {
6411 if (r->is_continues_humongous()) {
6412 return false;
6413 }
6414
6415 if (r->is_empty()) {
6416 // Add free regions to the free list
6417 r->set_free();
6418 r->set_allocation_context(AllocationContext::system());
6419 _hrm->insert_into_free_list(r);
6420 } else if (!_free_list_only) {
6421 assert(!r->is_young(), "we should not come across young regions");
6422
6423 if (r->is_humongous()) {
6424 // We ignore humongous regions, we left the humongous set unchanged
6425 } else {
6426 // Objects that were compacted would have ended up on regions
6427 // that were previously old or free. Archive regions (which are
6428 // old) will not have been touched.
6429 assert(r->is_free() || r->is_old(), "invariant");
6430 // We now consider them old, so register as such. Leave
6431 // archive regions set that way, however, while still adding
6432 // them to the old set.
6433 if (!r->is_archive()) {
6434 r->set_old();
6435 }
6436 _old_set->add(r);
6437 }
6438 _total_used += r->used();
6439 }
6440
6441 return false;
6442 }
6443
6444 size_t total_used() {
6445 return _total_used;
6446 }
6447 };
6448
6449 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6450 assert_at_safepoint(true /* should_be_vm_thread */);
6451
6452 if (!free_list_only) {
6453 _young_list->empty_list();
6454 }
6455
6456 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6457 heap_region_iterate(&cl);
6458
6459 if (!free_list_only) {
6460 _allocator->set_used(cl.total_used());
6461 if (_archive_allocator != NULL) {
6462 _archive_allocator->clear_used();
6463 }
6464 }
6465 assert(_allocator->used_unlocked() == recalculate_used(),
6466 err_msg("inconsistent _allocator->used_unlocked(), "
6467 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6468 _allocator->used_unlocked(), recalculate_used()));
6469 }
6470
6471 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6472 _refine_cte_cl->set_concurrent(concurrent);
6473 }
6474
6475 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6476 HeapRegion* hr = heap_region_containing(p);
6477 return hr->is_in(p);
6478 }
6479
6480 // Methods for the mutator alloc region
6481
6482 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6483 bool force) {
6484 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6485 assert(!force || g1_policy()->can_expand_young_list(),
6486 "if force is true we should be able to expand the young list");
6487 bool young_list_full = g1_policy()->is_young_list_full();
6488 if (force || !young_list_full) {
6489 HeapRegion* new_alloc_region = new_region(word_size,
6490 false /* is_old */,
6491 false /* do_expand */);
6492 if (new_alloc_region != NULL) {
6493 set_region_short_lived_locked(new_alloc_region);
6494 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6495 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6496 return new_alloc_region;
6497 }
6498 }
6499 return NULL;
6500 }
6501
6502 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6503 size_t allocated_bytes) {
6504 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6505 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6506
6507 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6508 _allocator->increase_used(allocated_bytes);
6509 _hr_printer.retire(alloc_region);
6510 // We update the eden sizes here, when the region is retired,
6511 // instead of when it's allocated, since this is the point that its
6512 // used space has been recored in _summary_bytes_used.
6513 g1mm()->update_eden_size();
6514 }
6515
6516 // Methods for the GC alloc regions
6517
6518 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6519 uint count,
6520 InCSetState dest) {
6521 assert(FreeList_lock->owned_by_self(), "pre-condition");
6522
6523 if (count < g1_policy()->max_regions(dest)) {
6524 const bool is_survivor = (dest.is_young());
6525 HeapRegion* new_alloc_region = new_region(word_size,
6526 !is_survivor,
6527 true /* do_expand */);
6528 if (new_alloc_region != NULL) {
6529 // We really only need to do this for old regions given that we
6530 // should never scan survivors. But it doesn't hurt to do it
6531 // for survivors too.
6532 new_alloc_region->record_timestamp();
6533 if (is_survivor) {
6534 new_alloc_region->set_survivor();
6535 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6536 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6537 } else {
6538 new_alloc_region->set_old();
6539 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6540 check_bitmaps("Old Region Allocation", new_alloc_region);
6541 }
6542 bool during_im = g1_policy()->during_initial_mark_pause();
6543 new_alloc_region->note_start_of_copying(during_im);
6544 return new_alloc_region;
6545 }
6546 }
6547 return NULL;
6548 }
6549
6550 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6551 size_t allocated_bytes,
6552 InCSetState dest) {
6553 bool during_im = g1_policy()->during_initial_mark_pause();
6554 alloc_region->note_end_of_copying(during_im);
6555 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6556 if (dest.is_young()) {
6557 young_list()->add_survivor_region(alloc_region);
6558 } else {
6559 _old_set.add(alloc_region);
6560 }
6561 _hr_printer.retire(alloc_region);
6562 }
6563
6564 HeapRegion* G1CollectedHeap::alloc_highest_available_region() {
6565 bool expanded = false;
6566 uint index = _hrm.find_highest_available(&expanded);
6567
6568 if (index != G1_NO_HRM_INDEX) {
6569 if (expanded) {
6570 ergo_verbose1(ErgoHeapSizing,
6571 "attempt heap expansion",
6572 ergo_format_reason("requested address range outside heap bounds")
6573 ergo_format_byte("region size"),
6574 HeapRegion::GrainWords * HeapWordSize);
6575 }
6576 _hrm.allocate_free_regions_starting_at(index, 1);
6577 return region_at(index);
6578 }
6579 return NULL;
6580 }
6581
6582
6583 // Heap region set verification
6584
6585 class VerifyRegionListsClosure : public HeapRegionClosure {
6586 private:
6587 HeapRegionSet* _old_set;
6588 HeapRegionSet* _humongous_set;
6589 HeapRegionManager* _hrm;
6590
6591 public:
6592 HeapRegionSetCount _old_count;
6593 HeapRegionSetCount _humongous_count;
6594 HeapRegionSetCount _free_count;
6595
6596 VerifyRegionListsClosure(HeapRegionSet* old_set,
6597 HeapRegionSet* humongous_set,
6598 HeapRegionManager* hrm) :
6599 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6600 _old_count(), _humongous_count(), _free_count(){ }
6601
6602 bool doHeapRegion(HeapRegion* hr) {
6603 if (hr->is_continues_humongous()) {
6604 return false;
6605 }
6606
6607 if (hr->is_young()) {
6608 // TODO
6609 } else if (hr->is_starts_humongous()) {
6610 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6611 _humongous_count.increment(1u, hr->capacity());
6612 } else if (hr->is_empty()) {
6613 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6614 _free_count.increment(1u, hr->capacity());
6615 } else if (hr->is_old()) {
6616 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6617 _old_count.increment(1u, hr->capacity());
6618 } else {
6619 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6620 ShouldNotReachHere();
6621 }
6622 return false;
6623 }
6624
6625 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6626 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6627 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6628 old_set->total_capacity_bytes(), _old_count.capacity()));
6629
6630 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6631 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6632 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6633
6634 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()));
6635 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6636 free_list->total_capacity_bytes(), _free_count.capacity()));
6637 }
6638 };
6639
6640 void G1CollectedHeap::verify_region_sets() {
6641 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6642
6643 // First, check the explicit lists.
6644 _hrm.verify();
6645 {
6646 // Given that a concurrent operation might be adding regions to
6647 // the secondary free list we have to take the lock before
6648 // verifying it.
6649 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6650 _secondary_free_list.verify_list();
6651 }
6652
6653 // If a concurrent region freeing operation is in progress it will
6654 // be difficult to correctly attributed any free regions we come
6655 // across to the correct free list given that they might belong to
6656 // one of several (free_list, secondary_free_list, any local lists,
6657 // etc.). So, if that's the case we will skip the rest of the
6658 // verification operation. Alternatively, waiting for the concurrent
6659 // operation to complete will have a non-trivial effect on the GC's
6660 // operation (no concurrent operation will last longer than the
6661 // interval between two calls to verification) and it might hide
6662 // any issues that we would like to catch during testing.
6663 if (free_regions_coming()) {
6664 return;
6665 }
6666
6667 // Make sure we append the secondary_free_list on the free_list so
6668 // that all free regions we will come across can be safely
6669 // attributed to the free_list.
6670 append_secondary_free_list_if_not_empty_with_lock();
6671
6672 // Finally, make sure that the region accounting in the lists is
6673 // consistent with what we see in the heap.
6674
6675 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6676 heap_region_iterate(&cl);
6677 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6678 }
6679
6680 // Optimized nmethod scanning
6681
6682 class RegisterNMethodOopClosure: public OopClosure {
6683 G1CollectedHeap* _g1h;
6684 nmethod* _nm;
6685
6686 template <class T> void do_oop_work(T* p) {
6687 T heap_oop = oopDesc::load_heap_oop(p);
6688 if (!oopDesc::is_null(heap_oop)) {
6689 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6690 HeapRegion* hr = _g1h->heap_region_containing(obj);
6691 assert(!hr->is_continues_humongous(),
6692 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6693 " starting at "HR_FORMAT,
6694 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6695
6696 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6697 hr->add_strong_code_root_locked(_nm);
6698 }
6699 }
6700
6701 public:
6702 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6703 _g1h(g1h), _nm(nm) {}
6704
6705 void do_oop(oop* p) { do_oop_work(p); }
6706 void do_oop(narrowOop* p) { do_oop_work(p); }
6707 };
6708
6709 class UnregisterNMethodOopClosure: public OopClosure {
6710 G1CollectedHeap* _g1h;
6711 nmethod* _nm;
6712
6713 template <class T> void do_oop_work(T* p) {
6714 T heap_oop = oopDesc::load_heap_oop(p);
6715 if (!oopDesc::is_null(heap_oop)) {
6716 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6717 HeapRegion* hr = _g1h->heap_region_containing(obj);
6718 assert(!hr->is_continues_humongous(),
6719 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6720 " starting at "HR_FORMAT,
6721 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6722
6723 hr->remove_strong_code_root(_nm);
6724 }
6725 }
6726
6727 public:
6728 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6729 _g1h(g1h), _nm(nm) {}
6730
6731 void do_oop(oop* p) { do_oop_work(p); }
6732 void do_oop(narrowOop* p) { do_oop_work(p); }
6733 };
6734
6735 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6736 CollectedHeap::register_nmethod(nm);
6737
6738 guarantee(nm != NULL, "sanity");
6739 RegisterNMethodOopClosure reg_cl(this, nm);
6740 nm->oops_do(®_cl);
6741 }
6742
6743 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6744 CollectedHeap::unregister_nmethod(nm);
6745
6746 guarantee(nm != NULL, "sanity");
6747 UnregisterNMethodOopClosure reg_cl(this, nm);
6748 nm->oops_do(®_cl, true);
6749 }
6750
6751 void G1CollectedHeap::purge_code_root_memory() {
6752 double purge_start = os::elapsedTime();
6753 G1CodeRootSet::purge();
6754 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6755 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6756 }
6757
6758 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6759 G1CollectedHeap* _g1h;
6760
6761 public:
6762 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6763 _g1h(g1h) {}
6764
6765 void do_code_blob(CodeBlob* cb) {
6766 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6767 if (nm == NULL) {
6768 return;
6769 }
6770
6771 if (ScavengeRootsInCode) {
6772 _g1h->register_nmethod(nm);
6773 }
6774 }
6775 };
6776
6777 void G1CollectedHeap::rebuild_strong_code_roots() {
6778 RebuildStrongCodeRootClosure blob_cl(this);
6779 CodeCache::blobs_do(&blob_cl);
6780 }