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/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "memory/allocation.hpp"
65 #include "memory/iterator.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72 #include "utilities/stack.inline.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
202 "incorrectly tagged (y: %d, surv: %d)",
203 p2i(curr->bottom()), p2i(curr->end()),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 p2i(curr->prev_top_at_mark_start()),
333 p2i(curr->next_top_at_mark_start()),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_pinned();
410 }
411
412 // Private methods.
413
414 HeapRegion*
415 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
416 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
417 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
418 if (!_secondary_free_list.is_empty()) {
419 if (G1ConcRegionFreeingVerbose) {
420 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
421 "secondary_free_list has %u entries",
422 _secondary_free_list.length());
423 }
424 // It looks as if there are free regions available on the
425 // secondary_free_list. Let's move them to the free_list and try
426 // again to allocate from it.
427 append_secondary_free_list();
428
429 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
430 "empty we should have moved at least one entry to the free_list");
431 HeapRegion* res = _hrm.allocate_free_region(is_old);
432 if (G1ConcRegionFreeingVerbose) {
433 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
434 "allocated " HR_FORMAT " from secondary_free_list",
435 HR_FORMAT_PARAMS(res));
436 }
437 return res;
438 }
439
440 // Wait here until we get notified either when (a) there are no
441 // more free regions coming or (b) some regions have been moved on
442 // the secondary_free_list.
443 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
444 }
445
446 if (G1ConcRegionFreeingVerbose) {
447 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
448 "could not allocate from secondary_free_list");
449 }
450 return NULL;
451 }
452
453 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
454 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
455 "the only time we use this to allocate a humongous region is "
456 "when we are allocating a single humongous region");
457
458 HeapRegion* res;
459 if (G1StressConcRegionFreeing) {
460 if (!_secondary_free_list.is_empty()) {
461 if (G1ConcRegionFreeingVerbose) {
462 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
463 "forced to look at the secondary_free_list");
464 }
465 res = new_region_try_secondary_free_list(is_old);
466 if (res != NULL) {
467 return res;
468 }
469 }
470 }
471
472 res = _hrm.allocate_free_region(is_old);
473
474 if (res == NULL) {
475 if (G1ConcRegionFreeingVerbose) {
476 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
477 "res == NULL, trying the secondary_free_list");
478 }
479 res = new_region_try_secondary_free_list(is_old);
480 }
481 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
482 // Currently, only attempts to allocate GC alloc regions set
483 // do_expand to true. So, we should only reach here during a
484 // safepoint. If this assumption changes we might have to
485 // reconsider the use of _expand_heap_after_alloc_failure.
486 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
487
488 ergo_verbose1(ErgoHeapSizing,
489 "attempt heap expansion",
490 ergo_format_reason("region allocation request failed")
491 ergo_format_byte("allocation request"),
492 word_size * HeapWordSize);
493 if (expand(word_size * HeapWordSize)) {
494 // Given that expand() succeeded in expanding the heap, and we
495 // always expand the heap by an amount aligned to the heap
496 // region size, the free list should in theory not be empty.
497 // In either case allocate_free_region() will check for NULL.
498 res = _hrm.allocate_free_region(is_old);
499 } else {
500 _expand_heap_after_alloc_failure = false;
501 }
502 }
503 return res;
504 }
505
506 HeapWord*
507 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
508 uint num_regions,
509 size_t word_size,
510 AllocationContext_t context) {
511 assert(first != G1_NO_HRM_INDEX, "pre-condition");
512 assert(is_humongous(word_size), "word_size should be humongous");
513 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
514
515 // Index of last region in the series + 1.
516 uint last = first + num_regions;
517
518 // We need to initialize the region(s) we just discovered. This is
519 // a bit tricky given that it can happen concurrently with
520 // refinement threads refining cards on these regions and
521 // potentially wanting to refine the BOT as they are scanning
522 // those cards (this can happen shortly after a cleanup; see CR
523 // 6991377). So we have to set up the region(s) carefully and in
524 // a specific order.
525
526 // The word size sum of all the regions we will allocate.
527 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
528 assert(word_size <= word_size_sum, "sanity");
529
530 // This will be the "starts humongous" region.
531 HeapRegion* first_hr = region_at(first);
532 // The header of the new object will be placed at the bottom of
533 // the first region.
534 HeapWord* new_obj = first_hr->bottom();
535 // This will be the new end of the first region in the series that
536 // should also match the end of the last region in the series.
537 HeapWord* new_end = new_obj + word_size_sum;
538 // This will be the new top of the first region that will reflect
539 // this allocation.
540 HeapWord* new_top = new_obj + word_size;
541
542 // First, we need to zero the header of the space that we will be
543 // allocating. When we update top further down, some refinement
544 // threads might try to scan the region. By zeroing the header we
545 // ensure that any thread that will try to scan the region will
546 // come across the zero klass word and bail out.
547 //
548 // NOTE: It would not have been correct to have used
549 // CollectedHeap::fill_with_object() and make the space look like
550 // an int array. The thread that is doing the allocation will
551 // later update the object header to a potentially different array
552 // type and, for a very short period of time, the klass and length
553 // fields will be inconsistent. This could cause a refinement
554 // thread to calculate the object size incorrectly.
555 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
556
557 // We will set up the first region as "starts humongous". This
558 // will also update the BOT covering all the regions to reflect
559 // that there is a single object that starts at the bottom of the
560 // first region.
561 first_hr->set_starts_humongous(new_top, new_end);
562 first_hr->set_allocation_context(context);
563 // Then, if there are any, we will set up the "continues
564 // humongous" regions.
565 HeapRegion* hr = NULL;
566 for (uint i = first + 1; i < last; ++i) {
567 hr = region_at(i);
568 hr->set_continues_humongous(first_hr);
569 hr->set_allocation_context(context);
570 }
571 // If we have "continues humongous" regions (hr != NULL), then the
572 // end of the last one should match new_end.
573 assert(hr == NULL || hr->end() == new_end, "sanity");
574
575 // Up to this point no concurrent thread would have been able to
576 // do any scanning on any region in this series. All the top
577 // fields still point to bottom, so the intersection between
578 // [bottom,top] and [card_start,card_end] will be empty. Before we
579 // update the top fields, we'll do a storestore to make sure that
580 // no thread sees the update to top before the zeroing of the
581 // object header and the BOT initialization.
582 OrderAccess::storestore();
583
584 // Now that the BOT and the object header have been initialized,
585 // we can update top of the "starts humongous" region.
586 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
587 "new_top should be in this region");
588 first_hr->set_top(new_top);
589 if (_hr_printer.is_active()) {
590 HeapWord* bottom = first_hr->bottom();
591 HeapWord* end = first_hr->orig_end();
592 if ((first + 1) == last) {
593 // the series has a single humongous region
594 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
595 } else {
596 // the series has more than one humongous regions
597 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
598 }
599 }
600
601 // Now, we will update the top fields of the "continues humongous"
602 // regions. The reason we need to do this is that, otherwise,
603 // these regions would look empty and this will confuse parts of
604 // G1. For example, the code that looks for a consecutive number
605 // of empty regions will consider them empty and try to
606 // re-allocate them. We can extend is_empty() to also include
607 // !is_continues_humongous(), but it is easier to just update the top
608 // fields here. The way we set top for all regions (i.e., top ==
609 // end for all regions but the last one, top == new_top for the
610 // last one) is actually used when we will free up the humongous
611 // region in free_humongous_region().
612 hr = NULL;
613 for (uint i = first + 1; i < last; ++i) {
614 hr = region_at(i);
615 if ((i + 1) == last) {
616 // last continues humongous region
617 assert(hr->bottom() < new_top && new_top <= hr->end(),
618 "new_top should fall on this region");
619 hr->set_top(new_top);
620 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
621 } else {
622 // not last one
623 assert(new_top > hr->end(), "new_top should be above this region");
624 hr->set_top(hr->end());
625 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
626 }
627 }
628 // If we have continues humongous regions (hr != NULL), then the
629 // end of the last one should match new_end and its top should
630 // match new_top.
631 assert(hr == NULL ||
632 (hr->end() == new_end && hr->top() == new_top), "sanity");
633 check_bitmaps("Humongous Region Allocation", first_hr);
634
635 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
636 increase_used(first_hr->used());
637 _humongous_set.add(first_hr);
638
639 return new_obj;
640 }
641
642 // If could fit into free regions w/o expansion, try.
643 // Otherwise, if can expand, do so.
644 // Otherwise, if using ex regions might help, try with ex given back.
645 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
647
648 verify_region_sets_optional();
649
650 uint first = G1_NO_HRM_INDEX;
651 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
652
653 if (obj_regions == 1) {
654 // Only one region to allocate, try to use a fast path by directly allocating
655 // from the free lists. Do not try to expand here, we will potentially do that
656 // later.
657 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
658 if (hr != NULL) {
659 first = hr->hrm_index();
660 }
661 } else {
662 // We can't allocate humongous regions spanning more than one region while
663 // cleanupComplete() is running, since some of the regions we find to be
664 // empty might not yet be added to the free list. It is not straightforward
665 // to know in which list they are on so that we can remove them. We only
666 // need to do this if we need to allocate more than one region to satisfy the
667 // current humongous allocation request. If we are only allocating one region
668 // we use the one-region region allocation code (see above), that already
669 // potentially waits for regions from the secondary free list.
670 wait_while_free_regions_coming();
671 append_secondary_free_list_if_not_empty_with_lock();
672
673 // Policy: Try only empty regions (i.e. already committed first). Maybe we
674 // are lucky enough to find some.
675 first = _hrm.find_contiguous_only_empty(obj_regions);
676 if (first != G1_NO_HRM_INDEX) {
677 _hrm.allocate_free_regions_starting_at(first, obj_regions);
678 }
679 }
680
681 if (first == G1_NO_HRM_INDEX) {
682 // Policy: We could not find enough regions for the humongous object in the
683 // free list. Look through the heap to find a mix of free and uncommitted regions.
684 // If so, try expansion.
685 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
686 if (first != G1_NO_HRM_INDEX) {
687 // We found something. Make sure these regions are committed, i.e. expand
688 // the heap. Alternatively we could do a defragmentation GC.
689 ergo_verbose1(ErgoHeapSizing,
690 "attempt heap expansion",
691 ergo_format_reason("humongous allocation request failed")
692 ergo_format_byte("allocation request"),
693 word_size * HeapWordSize);
694
695 _hrm.expand_at(first, obj_regions);
696 g1_policy()->record_new_heap_size(num_regions());
697
698 #ifdef ASSERT
699 for (uint i = first; i < first + obj_regions; ++i) {
700 HeapRegion* hr = region_at(i);
701 assert(hr->is_free(), "sanity");
702 assert(hr->is_empty(), "sanity");
703 assert(is_on_master_free_list(hr), "sanity");
704 }
705 #endif
706 _hrm.allocate_free_regions_starting_at(first, obj_regions);
707 } else {
708 // Policy: Potentially trigger a defragmentation GC.
709 }
710 }
711
712 HeapWord* result = NULL;
713 if (first != G1_NO_HRM_INDEX) {
714 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
715 word_size, context);
716 assert(result != NULL, "it should always return a valid result");
717
718 // A successful humongous object allocation changes the used space
719 // information of the old generation so we need to recalculate the
720 // sizes and update the jstat counters here.
721 g1mm()->update_sizes();
722 }
723
724 verify_region_sets_optional();
725
726 return result;
727 }
728
729 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
730 assert_heap_not_locked_and_not_at_safepoint();
731 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
732
733 uint dummy_gc_count_before;
734 uint dummy_gclocker_retry_count = 0;
735 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
736 }
737
738 HeapWord*
739 G1CollectedHeap::mem_allocate(size_t word_size,
740 bool* gc_overhead_limit_was_exceeded) {
741 assert_heap_not_locked_and_not_at_safepoint();
742
743 // Loop until the allocation is satisfied, or unsatisfied after GC.
744 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
745 uint gc_count_before;
746
747 HeapWord* result = NULL;
748 if (!is_humongous(word_size)) {
749 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
750 } else {
751 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
752 }
753 if (result != NULL) {
754 return result;
755 }
756
757 // Create the garbage collection operation...
758 VM_G1CollectForAllocation op(gc_count_before, word_size);
759 op.set_allocation_context(AllocationContext::current());
760
761 // ...and get the VM thread to execute it.
762 VMThread::execute(&op);
763
764 if (op.prologue_succeeded() && op.pause_succeeded()) {
765 // If the operation was successful we'll return the result even
766 // if it is NULL. If the allocation attempt failed immediately
767 // after a Full GC, it's unlikely we'll be able to allocate now.
768 HeapWord* result = op.result();
769 if (result != NULL && !is_humongous(word_size)) {
770 // Allocations that take place on VM operations do not do any
771 // card dirtying and we have to do it here. We only have to do
772 // this for non-humongous allocations, though.
773 dirty_young_block(result, word_size);
774 }
775 return result;
776 } else {
777 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
778 return NULL;
779 }
780 assert(op.result() == NULL,
781 "the result should be NULL if the VM op did not succeed");
782 }
783
784 // Give a warning if we seem to be looping forever.
785 if ((QueuedAllocationWarningCount > 0) &&
786 (try_count % QueuedAllocationWarningCount == 0)) {
787 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
788 }
789 }
790
791 ShouldNotReachHere();
792 return NULL;
793 }
794
795 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
796 AllocationContext_t context,
797 uint* gc_count_before_ret,
798 uint* gclocker_retry_count_ret) {
799 // Make sure you read the note in attempt_allocation_humongous().
800
801 assert_heap_not_locked_and_not_at_safepoint();
802 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
803 "be called for humongous allocation requests");
804
805 // We should only get here after the first-level allocation attempt
806 // (attempt_allocation()) failed to allocate.
807
808 // We will loop until a) we manage to successfully perform the
809 // allocation or b) we successfully schedule a collection which
810 // fails to perform the allocation. b) is the only case when we'll
811 // return NULL.
812 HeapWord* result = NULL;
813 for (int try_count = 1; /* we'll return */; try_count += 1) {
814 bool should_try_gc;
815 uint gc_count_before;
816
817 {
818 MutexLockerEx x(Heap_lock);
819 result = _allocator->attempt_allocation_locked(word_size, context);
820 if (result != NULL) {
821 return result;
822 }
823
824 if (GC_locker::is_active_and_needs_gc()) {
825 if (g1_policy()->can_expand_young_list()) {
826 // No need for an ergo verbose message here,
827 // can_expand_young_list() does this when it returns true.
828 result = _allocator->attempt_allocation_force(word_size, context);
829 if (result != NULL) {
830 return result;
831 }
832 }
833 should_try_gc = false;
834 } else {
835 // The GCLocker may not be active but the GCLocker initiated
836 // GC may not yet have been performed (GCLocker::needs_gc()
837 // returns true). In this case we do not try this GC and
838 // wait until the GCLocker initiated GC is performed, and
839 // then retry the allocation.
840 if (GC_locker::needs_gc()) {
841 should_try_gc = false;
842 } else {
843 // Read the GC count while still holding the Heap_lock.
844 gc_count_before = total_collections();
845 should_try_gc = true;
846 }
847 }
848 }
849
850 if (should_try_gc) {
851 bool succeeded;
852 result = do_collection_pause(word_size, gc_count_before, &succeeded,
853 GCCause::_g1_inc_collection_pause);
854 if (result != NULL) {
855 assert(succeeded, "only way to get back a non-NULL result");
856 return result;
857 }
858
859 if (succeeded) {
860 // If we get here we successfully scheduled a collection which
861 // failed to allocate. No point in trying to allocate
862 // further. We'll just return NULL.
863 MutexLockerEx x(Heap_lock);
864 *gc_count_before_ret = total_collections();
865 return NULL;
866 }
867 } else {
868 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
869 MutexLockerEx x(Heap_lock);
870 *gc_count_before_ret = total_collections();
871 return NULL;
872 }
873 // The GCLocker is either active or the GCLocker initiated
874 // GC has not yet been performed. Stall until it is and
875 // then retry the allocation.
876 GC_locker::stall_until_clear();
877 (*gclocker_retry_count_ret) += 1;
878 }
879
880 // We can reach here if we were unsuccessful in scheduling a
881 // collection (because another thread beat us to it) or if we were
882 // stalled due to the GC locker. In either can we should retry the
883 // allocation attempt in case another thread successfully
884 // performed a collection and reclaimed enough space. We do the
885 // first attempt (without holding the Heap_lock) here and the
886 // follow-on attempt will be at the start of the next loop
887 // iteration (after taking the Heap_lock).
888 result = _allocator->attempt_allocation(word_size, context);
889 if (result != NULL) {
890 return result;
891 }
892
893 // Give a warning if we seem to be looping forever.
894 if ((QueuedAllocationWarningCount > 0) &&
895 (try_count % QueuedAllocationWarningCount == 0)) {
896 warning("G1CollectedHeap::attempt_allocation_slow() "
897 "retries %d times", try_count);
898 }
899 }
900
901 ShouldNotReachHere();
902 return NULL;
903 }
904
905 void G1CollectedHeap::begin_archive_alloc_range() {
906 assert_at_safepoint(true /* should_be_vm_thread */);
907 if (_archive_allocator == NULL) {
908 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
909 }
910 }
911
912 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
913 // Allocations in archive regions cannot be of a size that would be considered
914 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
915 // may be different at archive-restore time.
916 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
917 }
918
919 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
920 assert_at_safepoint(true /* should_be_vm_thread */);
921 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
922 if (is_archive_alloc_too_large(word_size)) {
923 return NULL;
924 }
925 return _archive_allocator->archive_mem_allocate(word_size);
926 }
927
928 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
929 size_t end_alignment_in_bytes) {
930 assert_at_safepoint(true /* should_be_vm_thread */);
931 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
932
933 // Call complete_archive to do the real work, filling in the MemRegion
934 // array with the archive regions.
935 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
936 delete _archive_allocator;
937 _archive_allocator = NULL;
938 }
939
940 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
941 assert(ranges != NULL, "MemRegion array NULL");
942 assert(count != 0, "No MemRegions provided");
943 MemRegion reserved = _hrm.reserved();
944 for (size_t i = 0; i < count; i++) {
945 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
946 return false;
947 }
948 }
949 return true;
950 }
951
952 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
953 assert(!is_init_completed(), "Expect to be called at JVM init time");
954 assert(ranges != NULL, "MemRegion array NULL");
955 assert(count != 0, "No MemRegions provided");
956 MutexLockerEx x(Heap_lock);
957
958 MemRegion reserved = _hrm.reserved();
959 HeapWord* prev_last_addr = NULL;
960 HeapRegion* prev_last_region = NULL;
961
962 // Temporarily disable pretouching of heap pages. This interface is used
963 // when mmap'ing archived heap data in, so pre-touching is wasted.
964 FlagSetting fs(AlwaysPreTouch, false);
965
966 // Enable archive object checking in G1MarkSweep. We have to let it know
967 // about each archive range, so that objects in those ranges aren't marked.
968 G1MarkSweep::enable_archive_object_check();
969
970 // For each specified MemRegion range, allocate the corresponding G1
971 // regions and mark them as archive regions. We expect the ranges in
972 // ascending starting address order, without overlap.
973 for (size_t i = 0; i < count; i++) {
974 MemRegion curr_range = ranges[i];
975 HeapWord* start_address = curr_range.start();
976 size_t word_size = curr_range.word_size();
977 HeapWord* last_address = curr_range.last();
978 size_t commits = 0;
979
980 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
981 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
982 p2i(start_address), p2i(last_address)));
983 guarantee(start_address > prev_last_addr,
984 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
985 p2i(start_address), p2i(prev_last_addr)));
986 prev_last_addr = last_address;
987
988 // Check for ranges that start in the same G1 region in which the previous
989 // range ended, and adjust the start address so we don't try to allocate
990 // the same region again. If the current range is entirely within that
991 // region, skip it, just adjusting the recorded top.
992 HeapRegion* start_region = _hrm.addr_to_region(start_address);
993 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
994 start_address = start_region->end();
995 if (start_address > last_address) {
996 increase_used(word_size * HeapWordSize);
997 start_region->set_top(last_address + 1);
998 continue;
999 }
1000 start_region->set_top(start_address);
1001 curr_range = MemRegion(start_address, last_address + 1);
1002 start_region = _hrm.addr_to_region(start_address);
1003 }
1004
1005 // Perform the actual region allocation, exiting if it fails.
1006 // Then note how much new space we have allocated.
1007 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1008 return false;
1009 }
1010 increase_used(word_size * HeapWordSize);
1011 if (commits != 0) {
1012 ergo_verbose1(ErgoHeapSizing,
1013 "attempt heap expansion",
1014 ergo_format_reason("allocate archive regions")
1015 ergo_format_byte("total size"),
1016 HeapRegion::GrainWords * HeapWordSize * commits);
1017 }
1018
1019 // Mark each G1 region touched by the range as archive, add it to the old set,
1020 // and set the allocation context and top.
1021 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1022 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1023 prev_last_region = last_region;
1024
1025 while (curr_region != NULL) {
1026 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1027 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1028 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1029 curr_region->set_allocation_context(AllocationContext::system());
1030 curr_region->set_archive();
1031 _old_set.add(curr_region);
1032 if (curr_region != last_region) {
1033 curr_region->set_top(curr_region->end());
1034 curr_region = _hrm.next_region_in_heap(curr_region);
1035 } else {
1036 curr_region->set_top(last_address + 1);
1037 curr_region = NULL;
1038 }
1039 }
1040
1041 // Notify mark-sweep of the archive range.
1042 G1MarkSweep::set_range_archive(curr_range, true);
1043 }
1044 return true;
1045 }
1046
1047 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1048 assert(!is_init_completed(), "Expect to be called at JVM init time");
1049 assert(ranges != NULL, "MemRegion array NULL");
1050 assert(count != 0, "No MemRegions provided");
1051 MemRegion reserved = _hrm.reserved();
1052 HeapWord *prev_last_addr = NULL;
1053 HeapRegion* prev_last_region = NULL;
1054
1055 // For each MemRegion, create filler objects, if needed, in the G1 regions
1056 // that contain the address range. The address range actually within the
1057 // MemRegion will not be modified. That is assumed to have been initialized
1058 // elsewhere, probably via an mmap of archived heap data.
1059 MutexLockerEx x(Heap_lock);
1060 for (size_t i = 0; i < count; i++) {
1061 HeapWord* start_address = ranges[i].start();
1062 HeapWord* last_address = ranges[i].last();
1063
1064 assert(reserved.contains(start_address) && reserved.contains(last_address),
1065 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1066 p2i(start_address), p2i(last_address)));
1067 assert(start_address > prev_last_addr,
1068 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1069 p2i(start_address), p2i(prev_last_addr)));
1070
1071 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1072 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1073 HeapWord* bottom_address = start_region->bottom();
1074
1075 // Check for a range beginning in the same region in which the
1076 // previous one ended.
1077 if (start_region == prev_last_region) {
1078 bottom_address = prev_last_addr + 1;
1079 }
1080
1081 // Verify that the regions were all marked as archive regions by
1082 // alloc_archive_regions.
1083 HeapRegion* curr_region = start_region;
1084 while (curr_region != NULL) {
1085 guarantee(curr_region->is_archive(),
1086 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1087 if (curr_region != last_region) {
1088 curr_region = _hrm.next_region_in_heap(curr_region);
1089 } else {
1090 curr_region = NULL;
1091 }
1092 }
1093
1094 prev_last_addr = last_address;
1095 prev_last_region = last_region;
1096
1097 // Fill the memory below the allocated range with dummy object(s),
1098 // if the region bottom does not match the range start, or if the previous
1099 // range ended within the same G1 region, and there is a gap.
1100 if (start_address != bottom_address) {
1101 size_t fill_size = pointer_delta(start_address, bottom_address);
1102 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1103 increase_used(fill_size * HeapWordSize);
1104 }
1105 }
1106 }
1107
1108 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1109 uint* gc_count_before_ret,
1110 uint* gclocker_retry_count_ret) {
1111 assert_heap_not_locked_and_not_at_safepoint();
1112 assert(!is_humongous(word_size), "attempt_allocation() should not "
1113 "be called for humongous allocation requests");
1114
1115 AllocationContext_t context = AllocationContext::current();
1116 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1117
1118 if (result == NULL) {
1119 result = attempt_allocation_slow(word_size,
1120 context,
1121 gc_count_before_ret,
1122 gclocker_retry_count_ret);
1123 }
1124 assert_heap_not_locked();
1125 if (result != NULL) {
1126 dirty_young_block(result, word_size);
1127 }
1128 return result;
1129 }
1130
1131 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1132 assert(!is_init_completed(), "Expect to be called at JVM init time");
1133 assert(ranges != NULL, "MemRegion array NULL");
1134 assert(count != 0, "No MemRegions provided");
1135 MemRegion reserved = _hrm.reserved();
1136 HeapWord* prev_last_addr = NULL;
1137 HeapRegion* prev_last_region = NULL;
1138 size_t size_used = 0;
1139 size_t uncommitted_regions = 0;
1140
1141 // For each Memregion, free the G1 regions that constitute it, and
1142 // notify mark-sweep that the range is no longer to be considered 'archive.'
1143 MutexLockerEx x(Heap_lock);
1144 for (size_t i = 0; i < count; i++) {
1145 HeapWord* start_address = ranges[i].start();
1146 HeapWord* last_address = ranges[i].last();
1147
1148 assert(reserved.contains(start_address) && reserved.contains(last_address),
1149 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1150 p2i(start_address), p2i(last_address)));
1151 assert(start_address > prev_last_addr,
1152 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1153 p2i(start_address), p2i(prev_last_addr)));
1154 size_used += ranges[i].byte_size();
1155 prev_last_addr = last_address;
1156
1157 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1158 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1159
1160 // Check for ranges that start in the same G1 region in which the previous
1161 // range ended, and adjust the start address so we don't try to free
1162 // the same region again. If the current range is entirely within that
1163 // region, skip it.
1164 if (start_region == prev_last_region) {
1165 start_address = start_region->end();
1166 if (start_address > last_address) {
1167 continue;
1168 }
1169 start_region = _hrm.addr_to_region(start_address);
1170 }
1171 prev_last_region = last_region;
1172
1173 // After verifying that each region was marked as an archive region by
1174 // alloc_archive_regions, set it free and empty and uncommit it.
1175 HeapRegion* curr_region = start_region;
1176 while (curr_region != NULL) {
1177 guarantee(curr_region->is_archive(),
1178 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1179 uint curr_index = curr_region->hrm_index();
1180 _old_set.remove(curr_region);
1181 curr_region->set_free();
1182 curr_region->set_top(curr_region->bottom());
1183 if (curr_region != last_region) {
1184 curr_region = _hrm.next_region_in_heap(curr_region);
1185 } else {
1186 curr_region = NULL;
1187 }
1188 _hrm.shrink_at(curr_index, 1);
1189 uncommitted_regions++;
1190 }
1191
1192 // Notify mark-sweep that this is no longer an archive range.
1193 G1MarkSweep::set_range_archive(ranges[i], false);
1194 }
1195
1196 if (uncommitted_regions != 0) {
1197 ergo_verbose1(ErgoHeapSizing,
1198 "attempt heap shrinking",
1199 ergo_format_reason("uncommitted archive regions")
1200 ergo_format_byte("total size"),
1201 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1202 }
1203 decrease_used(size_used);
1204 }
1205
1206 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1207 uint* gc_count_before_ret,
1208 uint* gclocker_retry_count_ret) {
1209 // The structure of this method has a lot of similarities to
1210 // attempt_allocation_slow(). The reason these two were not merged
1211 // into a single one is that such a method would require several "if
1212 // allocation is not humongous do this, otherwise do that"
1213 // conditional paths which would obscure its flow. In fact, an early
1214 // version of this code did use a unified method which was harder to
1215 // follow and, as a result, it had subtle bugs that were hard to
1216 // track down. So keeping these two methods separate allows each to
1217 // be more readable. It will be good to keep these two in sync as
1218 // much as possible.
1219
1220 assert_heap_not_locked_and_not_at_safepoint();
1221 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1222 "should only be called for humongous allocations");
1223
1224 // Humongous objects can exhaust the heap quickly, so we should check if we
1225 // need to start a marking cycle at each humongous object allocation. We do
1226 // the check before we do the actual allocation. The reason for doing it
1227 // before the allocation is that we avoid having to keep track of the newly
1228 // allocated memory while we do a GC.
1229 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1230 word_size)) {
1231 collect(GCCause::_g1_humongous_allocation);
1232 }
1233
1234 // We will loop until a) we manage to successfully perform the
1235 // allocation or b) we successfully schedule a collection which
1236 // fails to perform the allocation. b) is the only case when we'll
1237 // return NULL.
1238 HeapWord* result = NULL;
1239 for (int try_count = 1; /* we'll return */; try_count += 1) {
1240 bool should_try_gc;
1241 uint gc_count_before;
1242
1243 {
1244 MutexLockerEx x(Heap_lock);
1245
1246 // Given that humongous objects are not allocated in young
1247 // regions, we'll first try to do the allocation without doing a
1248 // collection hoping that there's enough space in the heap.
1249 result = humongous_obj_allocate(word_size, AllocationContext::current());
1250 if (result != NULL) {
1251 return result;
1252 }
1253
1254 if (GC_locker::is_active_and_needs_gc()) {
1255 should_try_gc = false;
1256 } else {
1257 // The GCLocker may not be active but the GCLocker initiated
1258 // GC may not yet have been performed (GCLocker::needs_gc()
1259 // returns true). In this case we do not try this GC and
1260 // wait until the GCLocker initiated GC is performed, and
1261 // then retry the allocation.
1262 if (GC_locker::needs_gc()) {
1263 should_try_gc = false;
1264 } else {
1265 // Read the GC count while still holding the Heap_lock.
1266 gc_count_before = total_collections();
1267 should_try_gc = true;
1268 }
1269 }
1270 }
1271
1272 if (should_try_gc) {
1273 // If we failed to allocate the humongous object, we should try to
1274 // do a collection pause (if we're allowed) in case it reclaims
1275 // enough space for the allocation to succeed after the pause.
1276
1277 bool succeeded;
1278 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1279 GCCause::_g1_humongous_allocation);
1280 if (result != NULL) {
1281 assert(succeeded, "only way to get back a non-NULL result");
1282 return result;
1283 }
1284
1285 if (succeeded) {
1286 // If we get here we successfully scheduled a collection which
1287 // failed to allocate. No point in trying to allocate
1288 // further. We'll just return NULL.
1289 MutexLockerEx x(Heap_lock);
1290 *gc_count_before_ret = total_collections();
1291 return NULL;
1292 }
1293 } else {
1294 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1295 MutexLockerEx x(Heap_lock);
1296 *gc_count_before_ret = total_collections();
1297 return NULL;
1298 }
1299 // The GCLocker is either active or the GCLocker initiated
1300 // GC has not yet been performed. Stall until it is and
1301 // then retry the allocation.
1302 GC_locker::stall_until_clear();
1303 (*gclocker_retry_count_ret) += 1;
1304 }
1305
1306 // We can reach here if we were unsuccessful in scheduling a
1307 // collection (because another thread beat us to it) or if we were
1308 // stalled due to the GC locker. In either can we should retry the
1309 // allocation attempt in case another thread successfully
1310 // performed a collection and reclaimed enough space. Give a
1311 // warning if we seem to be looping forever.
1312
1313 if ((QueuedAllocationWarningCount > 0) &&
1314 (try_count % QueuedAllocationWarningCount == 0)) {
1315 warning("G1CollectedHeap::attempt_allocation_humongous() "
1316 "retries %d times", try_count);
1317 }
1318 }
1319
1320 ShouldNotReachHere();
1321 return NULL;
1322 }
1323
1324 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1325 AllocationContext_t context,
1326 bool expect_null_mutator_alloc_region) {
1327 assert_at_safepoint(true /* should_be_vm_thread */);
1328 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1329 "the current alloc region was unexpectedly found to be non-NULL");
1330
1331 if (!is_humongous(word_size)) {
1332 return _allocator->attempt_allocation_locked(word_size, context);
1333 } else {
1334 HeapWord* result = humongous_obj_allocate(word_size, context);
1335 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1336 collector_state()->set_initiate_conc_mark_if_possible(true);
1337 }
1338 return result;
1339 }
1340
1341 ShouldNotReachHere();
1342 }
1343
1344 class PostMCRemSetClearClosure: public HeapRegionClosure {
1345 G1CollectedHeap* _g1h;
1346 ModRefBarrierSet* _mr_bs;
1347 public:
1348 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1349 _g1h(g1h), _mr_bs(mr_bs) {}
1350
1351 bool doHeapRegion(HeapRegion* r) {
1352 HeapRegionRemSet* hrrs = r->rem_set();
1353
1354 if (r->is_continues_humongous()) {
1355 // We'll assert that the strong code root list and RSet is empty
1356 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1357 assert(hrrs->occupied() == 0, "RSet should be empty");
1358 return false;
1359 }
1360
1361 _g1h->reset_gc_time_stamps(r);
1362 hrrs->clear();
1363 // You might think here that we could clear just the cards
1364 // corresponding to the used region. But no: if we leave a dirty card
1365 // in a region we might allocate into, then it would prevent that card
1366 // from being enqueued, and cause it to be missed.
1367 // Re: the performance cost: we shouldn't be doing full GC anyway!
1368 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1369
1370 return false;
1371 }
1372 };
1373
1374 void G1CollectedHeap::clear_rsets_post_compaction() {
1375 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1376 heap_region_iterate(&rs_clear);
1377 }
1378
1379 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1380 G1CollectedHeap* _g1h;
1381 UpdateRSOopClosure _cl;
1382 public:
1383 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1384 _cl(g1->g1_rem_set(), worker_i),
1385 _g1h(g1)
1386 { }
1387
1388 bool doHeapRegion(HeapRegion* r) {
1389 if (!r->is_continues_humongous()) {
1390 _cl.set_from(r);
1391 r->oop_iterate(&_cl);
1392 }
1393 return false;
1394 }
1395 };
1396
1397 class ParRebuildRSTask: public AbstractGangTask {
1398 G1CollectedHeap* _g1;
1399 HeapRegionClaimer _hrclaimer;
1400
1401 public:
1402 ParRebuildRSTask(G1CollectedHeap* g1) :
1403 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1404
1405 void work(uint worker_id) {
1406 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1407 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1408 }
1409 };
1410
1411 class PostCompactionPrinterClosure: public HeapRegionClosure {
1412 private:
1413 G1HRPrinter* _hr_printer;
1414 public:
1415 bool doHeapRegion(HeapRegion* hr) {
1416 assert(!hr->is_young(), "not expecting to find young regions");
1417 if (hr->is_free()) {
1418 // We only generate output for non-empty regions.
1419 } else if (hr->is_starts_humongous()) {
1420 if (hr->region_num() == 1) {
1421 // single humongous region
1422 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1423 } else {
1424 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1425 }
1426 } else if (hr->is_continues_humongous()) {
1427 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1428 } else if (hr->is_archive()) {
1429 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1430 } else if (hr->is_old()) {
1431 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1432 } else {
1433 ShouldNotReachHere();
1434 }
1435 return false;
1436 }
1437
1438 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1439 : _hr_printer(hr_printer) { }
1440 };
1441
1442 void G1CollectedHeap::print_hrm_post_compaction() {
1443 PostCompactionPrinterClosure cl(hr_printer());
1444 heap_region_iterate(&cl);
1445 }
1446
1447 bool G1CollectedHeap::do_collection(bool explicit_gc,
1448 bool clear_all_soft_refs,
1449 size_t word_size) {
1450 assert_at_safepoint(true /* should_be_vm_thread */);
1451
1452 if (GC_locker::check_active_before_gc()) {
1453 return false;
1454 }
1455
1456 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1457 gc_timer->register_gc_start();
1458
1459 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1460 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1461
1462 SvcGCMarker sgcm(SvcGCMarker::FULL);
1463 ResourceMark rm;
1464
1465 G1Log::update_level();
1466 print_heap_before_gc();
1467 trace_heap_before_gc(gc_tracer);
1468
1469 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1470
1471 verify_region_sets_optional();
1472
1473 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1474 collector_policy()->should_clear_all_soft_refs();
1475
1476 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1477
1478 {
1479 IsGCActiveMark x;
1480
1481 // Timing
1482 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1483 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1484
1485 {
1486 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1487 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1488 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1489
1490 g1_policy()->record_full_collection_start();
1491
1492 // Note: When we have a more flexible GC logging framework that
1493 // allows us to add optional attributes to a GC log record we
1494 // could consider timing and reporting how long we wait in the
1495 // following two methods.
1496 wait_while_free_regions_coming();
1497 // If we start the compaction before the CM threads finish
1498 // scanning the root regions we might trip them over as we'll
1499 // be moving objects / updating references. So let's wait until
1500 // they are done. By telling them to abort, they should complete
1501 // early.
1502 _cm->root_regions()->abort();
1503 _cm->root_regions()->wait_until_scan_finished();
1504 append_secondary_free_list_if_not_empty_with_lock();
1505
1506 gc_prologue(true);
1507 increment_total_collections(true /* full gc */);
1508 increment_old_marking_cycles_started();
1509
1510 assert(used() == recalculate_used(), "Should be equal");
1511
1512 verify_before_gc();
1513
1514 check_bitmaps("Full GC Start");
1515 pre_full_gc_dump(gc_timer);
1516
1517 COMPILER2_PRESENT(DerivedPointerTable::clear());
1518
1519 // Disable discovery and empty the discovered lists
1520 // for the CM ref processor.
1521 ref_processor_cm()->disable_discovery();
1522 ref_processor_cm()->abandon_partial_discovery();
1523 ref_processor_cm()->verify_no_references_recorded();
1524
1525 // Abandon current iterations of concurrent marking and concurrent
1526 // refinement, if any are in progress. We have to do this before
1527 // wait_until_scan_finished() below.
1528 concurrent_mark()->abort();
1529
1530 // Make sure we'll choose a new allocation region afterwards.
1531 _allocator->release_mutator_alloc_region();
1532 _allocator->abandon_gc_alloc_regions();
1533 g1_rem_set()->cleanupHRRS();
1534
1535 // We should call this after we retire any currently active alloc
1536 // regions so that all the ALLOC / RETIRE events are generated
1537 // before the start GC event.
1538 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1539
1540 // We may have added regions to the current incremental collection
1541 // set between the last GC or pause and now. We need to clear the
1542 // incremental collection set and then start rebuilding it afresh
1543 // after this full GC.
1544 abandon_collection_set(g1_policy()->inc_cset_head());
1545 g1_policy()->clear_incremental_cset();
1546 g1_policy()->stop_incremental_cset_building();
1547
1548 tear_down_region_sets(false /* free_list_only */);
1549 collector_state()->set_gcs_are_young(true);
1550
1551 // See the comments in g1CollectedHeap.hpp and
1552 // G1CollectedHeap::ref_processing_init() about
1553 // how reference processing currently works in G1.
1554
1555 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1556 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1557
1558 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1559 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1560
1561 ref_processor_stw()->enable_discovery();
1562 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1563
1564 // Do collection work
1565 {
1566 HandleMark hm; // Discard invalid handles created during gc
1567 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1568 }
1569
1570 assert(num_free_regions() == 0, "we should not have added any free regions");
1571 rebuild_region_sets(false /* free_list_only */);
1572
1573 // Enqueue any discovered reference objects that have
1574 // not been removed from the discovered lists.
1575 ref_processor_stw()->enqueue_discovered_references();
1576
1577 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1578
1579 MemoryService::track_memory_usage();
1580
1581 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1582 ref_processor_stw()->verify_no_references_recorded();
1583
1584 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1585 ClassLoaderDataGraph::purge();
1586 MetaspaceAux::verify_metrics();
1587
1588 // Note: since we've just done a full GC, concurrent
1589 // marking is no longer active. Therefore we need not
1590 // re-enable reference discovery for the CM ref processor.
1591 // That will be done at the start of the next marking cycle.
1592 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1593 ref_processor_cm()->verify_no_references_recorded();
1594
1595 reset_gc_time_stamp();
1596 // Since everything potentially moved, we will clear all remembered
1597 // sets, and clear all cards. Later we will rebuild remembered
1598 // sets. We will also reset the GC time stamps of the regions.
1599 clear_rsets_post_compaction();
1600 check_gc_time_stamps();
1601
1602 // Resize the heap if necessary.
1603 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1604
1605 if (_hr_printer.is_active()) {
1606 // We should do this after we potentially resize the heap so
1607 // that all the COMMIT / UNCOMMIT events are generated before
1608 // the end GC event.
1609
1610 print_hrm_post_compaction();
1611 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1612 }
1613
1614 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1615 if (hot_card_cache->use_cache()) {
1616 hot_card_cache->reset_card_counts();
1617 hot_card_cache->reset_hot_cache();
1618 }
1619
1620 // Rebuild remembered sets of all regions.
1621 uint n_workers =
1622 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1623 workers()->active_workers(),
1624 Threads::number_of_non_daemon_threads());
1625 workers()->set_active_workers(n_workers);
1626
1627 ParRebuildRSTask rebuild_rs_task(this);
1628 workers()->run_task(&rebuild_rs_task);
1629
1630 // Rebuild the strong code root lists for each region
1631 rebuild_strong_code_roots();
1632
1633 if (true) { // FIXME
1634 MetaspaceGC::compute_new_size();
1635 }
1636
1637 #ifdef TRACESPINNING
1638 ParallelTaskTerminator::print_termination_counts();
1639 #endif
1640
1641 // Discard all rset updates
1642 JavaThread::dirty_card_queue_set().abandon_logs();
1643 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1644
1645 _young_list->reset_sampled_info();
1646 // At this point there should be no regions in the
1647 // entire heap tagged as young.
1648 assert(check_young_list_empty(true /* check_heap */),
1649 "young list should be empty at this point");
1650
1651 // Update the number of full collections that have been completed.
1652 increment_old_marking_cycles_completed(false /* concurrent */);
1653
1654 _hrm.verify_optional();
1655 verify_region_sets_optional();
1656
1657 verify_after_gc();
1658
1659 // Clear the previous marking bitmap, if needed for bitmap verification.
1660 // Note we cannot do this when we clear the next marking bitmap in
1661 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1662 // objects marked during a full GC against the previous bitmap.
1663 // But we need to clear it before calling check_bitmaps below since
1664 // the full GC has compacted objects and updated TAMS but not updated
1665 // the prev bitmap.
1666 if (G1VerifyBitmaps) {
1667 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1668 }
1669 check_bitmaps("Full GC End");
1670
1671 // Start a new incremental collection set for the next pause
1672 assert(g1_policy()->collection_set() == NULL, "must be");
1673 g1_policy()->start_incremental_cset_building();
1674
1675 clear_cset_fast_test();
1676
1677 _allocator->init_mutator_alloc_region();
1678
1679 g1_policy()->record_full_collection_end();
1680
1681 if (G1Log::fine()) {
1682 g1_policy()->print_heap_transition();
1683 }
1684
1685 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1686 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1687 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1688 // before any GC notifications are raised.
1689 g1mm()->update_sizes();
1690
1691 gc_epilogue(true);
1692 }
1693
1694 if (G1Log::finer()) {
1695 g1_policy()->print_detailed_heap_transition(true /* full */);
1696 }
1697
1698 print_heap_after_gc();
1699 trace_heap_after_gc(gc_tracer);
1700
1701 post_full_gc_dump(gc_timer);
1702
1703 gc_timer->register_gc_end();
1704 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1705 }
1706
1707 return true;
1708 }
1709
1710 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1711 // do_collection() will return whether it succeeded in performing
1712 // the GC. Currently, there is no facility on the
1713 // do_full_collection() API to notify the caller than the collection
1714 // did not succeed (e.g., because it was locked out by the GC
1715 // locker). So, right now, we'll ignore the return value.
1716 bool dummy = do_collection(true, /* explicit_gc */
1717 clear_all_soft_refs,
1718 0 /* word_size */);
1719 }
1720
1721 // This code is mostly copied from TenuredGeneration.
1722 void
1723 G1CollectedHeap::
1724 resize_if_necessary_after_full_collection(size_t word_size) {
1725 // Include the current allocation, if any, and bytes that will be
1726 // pre-allocated to support collections, as "used".
1727 const size_t used_after_gc = used();
1728 const size_t capacity_after_gc = capacity();
1729 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1730
1731 // This is enforced in arguments.cpp.
1732 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1733 "otherwise the code below doesn't make sense");
1734
1735 // We don't have floating point command-line arguments
1736 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1737 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1738 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1739 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1740
1741 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1742 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1743
1744 // We have to be careful here as these two calculations can overflow
1745 // 32-bit size_t's.
1746 double used_after_gc_d = (double) used_after_gc;
1747 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1748 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1749
1750 // Let's make sure that they are both under the max heap size, which
1751 // by default will make them fit into a size_t.
1752 double desired_capacity_upper_bound = (double) max_heap_size;
1753 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1754 desired_capacity_upper_bound);
1755 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1756 desired_capacity_upper_bound);
1757
1758 // We can now safely turn them into size_t's.
1759 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1760 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1761
1762 // This assert only makes sense here, before we adjust them
1763 // with respect to the min and max heap size.
1764 assert(minimum_desired_capacity <= maximum_desired_capacity,
1765 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1766 "maximum_desired_capacity = " SIZE_FORMAT,
1767 minimum_desired_capacity, maximum_desired_capacity));
1768
1769 // Should not be greater than the heap max size. No need to adjust
1770 // it with respect to the heap min size as it's a lower bound (i.e.,
1771 // we'll try to make the capacity larger than it, not smaller).
1772 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1773 // Should not be less than the heap min size. No need to adjust it
1774 // with respect to the heap max size as it's an upper bound (i.e.,
1775 // we'll try to make the capacity smaller than it, not greater).
1776 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1777
1778 if (capacity_after_gc < minimum_desired_capacity) {
1779 // Don't expand unless it's significant
1780 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1781 ergo_verbose4(ErgoHeapSizing,
1782 "attempt heap expansion",
1783 ergo_format_reason("capacity lower than "
1784 "min desired capacity after Full GC")
1785 ergo_format_byte("capacity")
1786 ergo_format_byte("occupancy")
1787 ergo_format_byte_perc("min desired capacity"),
1788 capacity_after_gc, used_after_gc,
1789 minimum_desired_capacity, (double) MinHeapFreeRatio);
1790 expand(expand_bytes);
1791
1792 // No expansion, now see if we want to shrink
1793 } else if (capacity_after_gc > maximum_desired_capacity) {
1794 // Capacity too large, compute shrinking size
1795 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1796 ergo_verbose4(ErgoHeapSizing,
1797 "attempt heap shrinking",
1798 ergo_format_reason("capacity higher than "
1799 "max desired capacity after Full GC")
1800 ergo_format_byte("capacity")
1801 ergo_format_byte("occupancy")
1802 ergo_format_byte_perc("max desired capacity"),
1803 capacity_after_gc, used_after_gc,
1804 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1805 shrink(shrink_bytes);
1806 }
1807 }
1808
1809
1810 HeapWord*
1811 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1812 AllocationContext_t context,
1813 bool* succeeded) {
1814 assert_at_safepoint(true /* should_be_vm_thread */);
1815
1816 *succeeded = true;
1817 // Let's attempt the allocation first.
1818 HeapWord* result =
1819 attempt_allocation_at_safepoint(word_size,
1820 context,
1821 false /* expect_null_mutator_alloc_region */);
1822 if (result != NULL) {
1823 assert(*succeeded, "sanity");
1824 return result;
1825 }
1826
1827 // In a G1 heap, we're supposed to keep allocation from failing by
1828 // incremental pauses. Therefore, at least for now, we'll favor
1829 // expansion over collection. (This might change in the future if we can
1830 // do something smarter than full collection to satisfy a failed alloc.)
1831 result = expand_and_allocate(word_size, context);
1832 if (result != NULL) {
1833 assert(*succeeded, "sanity");
1834 return result;
1835 }
1836
1837 // Expansion didn't work, we'll try to do a Full GC.
1838 bool gc_succeeded = do_collection(false, /* explicit_gc */
1839 false, /* clear_all_soft_refs */
1840 word_size);
1841 if (!gc_succeeded) {
1842 *succeeded = false;
1843 return NULL;
1844 }
1845
1846 // Retry the allocation
1847 result = attempt_allocation_at_safepoint(word_size,
1848 context,
1849 true /* expect_null_mutator_alloc_region */);
1850 if (result != NULL) {
1851 assert(*succeeded, "sanity");
1852 return result;
1853 }
1854
1855 // Then, try a Full GC that will collect all soft references.
1856 gc_succeeded = do_collection(false, /* explicit_gc */
1857 true, /* clear_all_soft_refs */
1858 word_size);
1859 if (!gc_succeeded) {
1860 *succeeded = false;
1861 return NULL;
1862 }
1863
1864 // Retry the allocation once more
1865 result = attempt_allocation_at_safepoint(word_size,
1866 context,
1867 true /* expect_null_mutator_alloc_region */);
1868 if (result != NULL) {
1869 assert(*succeeded, "sanity");
1870 return result;
1871 }
1872
1873 assert(!collector_policy()->should_clear_all_soft_refs(),
1874 "Flag should have been handled and cleared prior to this point");
1875
1876 // What else? We might try synchronous finalization later. If the total
1877 // space available is large enough for the allocation, then a more
1878 // complete compaction phase than we've tried so far might be
1879 // appropriate.
1880 assert(*succeeded, "sanity");
1881 return NULL;
1882 }
1883
1884 // Attempting to expand the heap sufficiently
1885 // to support an allocation of the given "word_size". If
1886 // successful, perform the allocation and return the address of the
1887 // allocated block, or else "NULL".
1888
1889 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1890 assert_at_safepoint(true /* should_be_vm_thread */);
1891
1892 verify_region_sets_optional();
1893
1894 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1895 ergo_verbose1(ErgoHeapSizing,
1896 "attempt heap expansion",
1897 ergo_format_reason("allocation request failed")
1898 ergo_format_byte("allocation request"),
1899 word_size * HeapWordSize);
1900 if (expand(expand_bytes)) {
1901 _hrm.verify_optional();
1902 verify_region_sets_optional();
1903 return attempt_allocation_at_safepoint(word_size,
1904 context,
1905 false /* expect_null_mutator_alloc_region */);
1906 }
1907 return NULL;
1908 }
1909
1910 bool G1CollectedHeap::expand(size_t expand_bytes) {
1911 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1912 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1913 HeapRegion::GrainBytes);
1914 ergo_verbose2(ErgoHeapSizing,
1915 "expand the heap",
1916 ergo_format_byte("requested expansion amount")
1917 ergo_format_byte("attempted expansion amount"),
1918 expand_bytes, aligned_expand_bytes);
1919
1920 if (is_maximal_no_gc()) {
1921 ergo_verbose0(ErgoHeapSizing,
1922 "did not expand the heap",
1923 ergo_format_reason("heap already fully expanded"));
1924 return false;
1925 }
1926
1927 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1928 assert(regions_to_expand > 0, "Must expand by at least one region");
1929
1930 uint expanded_by = _hrm.expand_by(regions_to_expand);
1931
1932 if (expanded_by > 0) {
1933 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1934 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1935 g1_policy()->record_new_heap_size(num_regions());
1936 } else {
1937 ergo_verbose0(ErgoHeapSizing,
1938 "did not expand the heap",
1939 ergo_format_reason("heap expansion operation failed"));
1940 // The expansion of the virtual storage space was unsuccessful.
1941 // Let's see if it was because we ran out of swap.
1942 if (G1ExitOnExpansionFailure &&
1943 _hrm.available() >= regions_to_expand) {
1944 // We had head room...
1945 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1946 }
1947 }
1948 return regions_to_expand > 0;
1949 }
1950
1951 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1952 size_t aligned_shrink_bytes =
1953 ReservedSpace::page_align_size_down(shrink_bytes);
1954 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1955 HeapRegion::GrainBytes);
1956 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1957
1958 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1959 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1960
1961 ergo_verbose3(ErgoHeapSizing,
1962 "shrink the heap",
1963 ergo_format_byte("requested shrinking amount")
1964 ergo_format_byte("aligned shrinking amount")
1965 ergo_format_byte("attempted shrinking amount"),
1966 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1967 if (num_regions_removed > 0) {
1968 g1_policy()->record_new_heap_size(num_regions());
1969 } else {
1970 ergo_verbose0(ErgoHeapSizing,
1971 "did not shrink the heap",
1972 ergo_format_reason("heap shrinking operation failed"));
1973 }
1974 }
1975
1976 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1977 verify_region_sets_optional();
1978
1979 // We should only reach here at the end of a Full GC which means we
1980 // should not not be holding to any GC alloc regions. The method
1981 // below will make sure of that and do any remaining clean up.
1982 _allocator->abandon_gc_alloc_regions();
1983
1984 // Instead of tearing down / rebuilding the free lists here, we
1985 // could instead use the remove_all_pending() method on free_list to
1986 // remove only the ones that we need to remove.
1987 tear_down_region_sets(true /* free_list_only */);
1988 shrink_helper(shrink_bytes);
1989 rebuild_region_sets(true /* free_list_only */);
1990
1991 _hrm.verify_optional();
1992 verify_region_sets_optional();
1993 }
1994
1995 // Public methods.
1996
1997 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1998 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1999 #endif // _MSC_VER
2000
2001
2002 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2003 CollectedHeap(),
2004 _g1_policy(policy_),
2005 _dirty_card_queue_set(false),
2006 _into_cset_dirty_card_queue_set(false),
2007 _is_alive_closure_cm(this),
2008 _is_alive_closure_stw(this),
2009 _ref_processor_cm(NULL),
2010 _ref_processor_stw(NULL),
2011 _bot_shared(NULL),
2012 _cg1r(NULL),
2013 _g1mm(NULL),
2014 _refine_cte_cl(NULL),
2015 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2016 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2017 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2018 _humongous_reclaim_candidates(),
2019 _has_humongous_reclaim_candidates(false),
2020 _archive_allocator(NULL),
2021 _free_regions_coming(false),
2022 _young_list(new YoungList(this)),
2023 _gc_time_stamp(0),
2024 _summary_bytes_used(0),
2025 _survivor_evac_stats(YoungPLABSize, PLABWeight),
2026 _old_evac_stats(OldPLABSize, PLABWeight),
2027 _expand_heap_after_alloc_failure(true),
2028 _old_marking_cycles_started(0),
2029 _old_marking_cycles_completed(0),
2030 _heap_summary_sent(false),
2031 _in_cset_fast_test(),
2032 _dirty_cards_region_list(NULL),
2033 _worker_cset_start_region(NULL),
2034 _worker_cset_start_region_time_stamp(NULL),
2035 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2036 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2037 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2038 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2039
2040 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2041 /* are_GC_task_threads */true,
2042 /* are_ConcurrentGC_threads */false);
2043 _workers->initialize_workers();
2044
2045 _allocator = G1Allocator::create_allocator(this);
2046 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2047
2048 // Override the default _filler_array_max_size so that no humongous filler
2049 // objects are created.
2050 _filler_array_max_size = _humongous_object_threshold_in_words;
2051
2052 uint n_queues = ParallelGCThreads;
2053 _task_queues = new RefToScanQueueSet(n_queues);
2054
2055 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2056 assert(n_rem_sets > 0, "Invariant.");
2057
2058 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2059 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2060 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2061
2062 for (uint i = 0; i < n_queues; i++) {
2063 RefToScanQueue* q = new RefToScanQueue();
2064 q->initialize();
2065 _task_queues->register_queue(i, q);
2066 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2067 }
2068 clear_cset_start_regions();
2069
2070 // Initialize the G1EvacuationFailureALot counters and flags.
2071 NOT_PRODUCT(reset_evacuation_should_fail();)
2072
2073 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2074 }
2075
2076 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2077 size_t size,
2078 size_t translation_factor) {
2079 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2080 // Allocate a new reserved space, preferring to use large pages.
2081 ReservedSpace rs(size, preferred_page_size);
2082 G1RegionToSpaceMapper* result =
2083 G1RegionToSpaceMapper::create_mapper(rs,
2084 size,
2085 rs.alignment(),
2086 HeapRegion::GrainBytes,
2087 translation_factor,
2088 mtGC);
2089 if (TracePageSizes) {
2090 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2091 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2092 }
2093 return result;
2094 }
2095
2096 jint G1CollectedHeap::initialize() {
2097 CollectedHeap::pre_initialize();
2098 os::enable_vtime();
2099
2100 G1Log::init();
2101
2102 // Necessary to satisfy locking discipline assertions.
2103
2104 MutexLocker x(Heap_lock);
2105
2106 // We have to initialize the printer before committing the heap, as
2107 // it will be used then.
2108 _hr_printer.set_active(G1PrintHeapRegions);
2109
2110 // While there are no constraints in the GC code that HeapWordSize
2111 // be any particular value, there are multiple other areas in the
2112 // system which believe this to be true (e.g. oop->object_size in some
2113 // cases incorrectly returns the size in wordSize units rather than
2114 // HeapWordSize).
2115 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2116
2117 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2118 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2119 size_t heap_alignment = collector_policy()->heap_alignment();
2120
2121 // Ensure that the sizes are properly aligned.
2122 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2123 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2124 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2125
2126 _refine_cte_cl = new RefineCardTableEntryClosure();
2127
2128 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2129
2130 // Reserve the maximum.
2131
2132 // When compressed oops are enabled, the preferred heap base
2133 // is calculated by subtracting the requested size from the
2134 // 32Gb boundary and using the result as the base address for
2135 // heap reservation. If the requested size is not aligned to
2136 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2137 // into the ReservedHeapSpace constructor) then the actual
2138 // base of the reserved heap may end up differing from the
2139 // address that was requested (i.e. the preferred heap base).
2140 // If this happens then we could end up using a non-optimal
2141 // compressed oops mode.
2142
2143 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2144 heap_alignment);
2145
2146 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2147
2148 // Create the barrier set for the entire reserved region.
2149 G1SATBCardTableLoggingModRefBS* bs
2150 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2151 bs->initialize();
2152 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2153 set_barrier_set(bs);
2154
2155 // Also create a G1 rem set.
2156 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2157
2158 // Carve out the G1 part of the heap.
2159
2160 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2161 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2162 G1RegionToSpaceMapper* heap_storage =
2163 G1RegionToSpaceMapper::create_mapper(g1_rs,
2164 g1_rs.size(),
2165 page_size,
2166 HeapRegion::GrainBytes,
2167 1,
2168 mtJavaHeap);
2169 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2170 max_byte_size, page_size,
2171 heap_rs.base(),
2172 heap_rs.size());
2173 heap_storage->set_mapping_changed_listener(&_listener);
2174
2175 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2176 G1RegionToSpaceMapper* bot_storage =
2177 create_aux_memory_mapper("Block offset table",
2178 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2179 G1BlockOffsetSharedArray::heap_map_factor());
2180
2181 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2182 G1RegionToSpaceMapper* cardtable_storage =
2183 create_aux_memory_mapper("Card table",
2184 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2185 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2186
2187 G1RegionToSpaceMapper* card_counts_storage =
2188 create_aux_memory_mapper("Card counts table",
2189 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2190 G1CardCounts::heap_map_factor());
2191
2192 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2193 G1RegionToSpaceMapper* prev_bitmap_storage =
2194 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2195 G1RegionToSpaceMapper* next_bitmap_storage =
2196 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2197
2198 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2199 g1_barrier_set()->initialize(cardtable_storage);
2200 // Do later initialization work for concurrent refinement.
2201 _cg1r->init(card_counts_storage);
2202
2203 // 6843694 - ensure that the maximum region index can fit
2204 // in the remembered set structures.
2205 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2206 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2207
2208 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2209 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2210 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2211 "too many cards per region");
2212
2213 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2214
2215 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2216
2217 {
2218 HeapWord* start = _hrm.reserved().start();
2219 HeapWord* end = _hrm.reserved().end();
2220 size_t granularity = HeapRegion::GrainBytes;
2221
2222 _in_cset_fast_test.initialize(start, end, granularity);
2223 _humongous_reclaim_candidates.initialize(start, end, granularity);
2224 }
2225
2226 // Create the ConcurrentMark data structure and thread.
2227 // (Must do this late, so that "max_regions" is defined.)
2228 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2229 if (_cm == NULL || !_cm->completed_initialization()) {
2230 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2231 return JNI_ENOMEM;
2232 }
2233 _cmThread = _cm->cmThread();
2234
2235 // Initialize the from_card cache structure of HeapRegionRemSet.
2236 HeapRegionRemSet::init_heap(max_regions());
2237
2238 // Now expand into the initial heap size.
2239 if (!expand(init_byte_size)) {
2240 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2241 return JNI_ENOMEM;
2242 }
2243
2244 // Perform any initialization actions delegated to the policy.
2245 g1_policy()->init();
2246
2247 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2248 SATB_Q_FL_lock,
2249 G1SATBProcessCompletedThreshold,
2250 Shared_SATB_Q_lock);
2251
2252 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2253 DirtyCardQ_CBL_mon,
2254 DirtyCardQ_FL_lock,
2255 concurrent_g1_refine()->yellow_zone(),
2256 concurrent_g1_refine()->red_zone(),
2257 Shared_DirtyCardQ_lock);
2258
2259 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2260 DirtyCardQ_CBL_mon,
2261 DirtyCardQ_FL_lock,
2262 -1, // never trigger processing
2263 -1, // no limit on length
2264 Shared_DirtyCardQ_lock,
2265 &JavaThread::dirty_card_queue_set());
2266
2267 // Initialize the card queue set used to hold cards containing
2268 // references into the collection set.
2269 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2270 DirtyCardQ_CBL_mon,
2271 DirtyCardQ_FL_lock,
2272 -1, // never trigger processing
2273 -1, // no limit on length
2274 Shared_DirtyCardQ_lock,
2275 &JavaThread::dirty_card_queue_set());
2276
2277 // Here we allocate the dummy HeapRegion that is required by the
2278 // G1AllocRegion class.
2279 HeapRegion* dummy_region = _hrm.get_dummy_region();
2280
2281 // We'll re-use the same region whether the alloc region will
2282 // require BOT updates or not and, if it doesn't, then a non-young
2283 // region will complain that it cannot support allocations without
2284 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2285 dummy_region->set_eden();
2286 // Make sure it's full.
2287 dummy_region->set_top(dummy_region->end());
2288 G1AllocRegion::setup(this, dummy_region);
2289
2290 _allocator->init_mutator_alloc_region();
2291
2292 // Do create of the monitoring and management support so that
2293 // values in the heap have been properly initialized.
2294 _g1mm = new G1MonitoringSupport(this);
2295
2296 G1StringDedup::initialize();
2297
2298 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2299 for (uint i = 0; i < ParallelGCThreads; i++) {
2300 new (&_preserved_objs[i]) OopAndMarkOopStack();
2301 }
2302
2303 return JNI_OK;
2304 }
2305
2306 void G1CollectedHeap::stop() {
2307 // Stop all concurrent threads. We do this to make sure these threads
2308 // do not continue to execute and access resources (e.g. gclog_or_tty)
2309 // that are destroyed during shutdown.
2310 _cg1r->stop();
2311 _cmThread->stop();
2312 if (G1StringDedup::is_enabled()) {
2313 G1StringDedup::stop();
2314 }
2315 }
2316
2317 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2318 return HeapRegion::max_region_size();
2319 }
2320
2321 void G1CollectedHeap::post_initialize() {
2322 CollectedHeap::post_initialize();
2323 ref_processing_init();
2324 }
2325
2326 void G1CollectedHeap::ref_processing_init() {
2327 // Reference processing in G1 currently works as follows:
2328 //
2329 // * There are two reference processor instances. One is
2330 // used to record and process discovered references
2331 // during concurrent marking; the other is used to
2332 // record and process references during STW pauses
2333 // (both full and incremental).
2334 // * Both ref processors need to 'span' the entire heap as
2335 // the regions in the collection set may be dotted around.
2336 //
2337 // * For the concurrent marking ref processor:
2338 // * Reference discovery is enabled at initial marking.
2339 // * Reference discovery is disabled and the discovered
2340 // references processed etc during remarking.
2341 // * Reference discovery is MT (see below).
2342 // * Reference discovery requires a barrier (see below).
2343 // * Reference processing may or may not be MT
2344 // (depending on the value of ParallelRefProcEnabled
2345 // and ParallelGCThreads).
2346 // * A full GC disables reference discovery by the CM
2347 // ref processor and abandons any entries on it's
2348 // discovered lists.
2349 //
2350 // * For the STW processor:
2351 // * Non MT discovery is enabled at the start of a full GC.
2352 // * Processing and enqueueing during a full GC is non-MT.
2353 // * During a full GC, references are processed after marking.
2354 //
2355 // * Discovery (may or may not be MT) is enabled at the start
2356 // of an incremental evacuation pause.
2357 // * References are processed near the end of a STW evacuation pause.
2358 // * For both types of GC:
2359 // * Discovery is atomic - i.e. not concurrent.
2360 // * Reference discovery will not need a barrier.
2361
2362 MemRegion mr = reserved_region();
2363
2364 // Concurrent Mark ref processor
2365 _ref_processor_cm =
2366 new ReferenceProcessor(mr, // span
2367 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2368 // mt processing
2369 ParallelGCThreads,
2370 // degree of mt processing
2371 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2372 // mt discovery
2373 MAX2(ParallelGCThreads, ConcGCThreads),
2374 // degree of mt discovery
2375 false,
2376 // Reference discovery is not atomic
2377 &_is_alive_closure_cm);
2378 // is alive closure
2379 // (for efficiency/performance)
2380
2381 // STW ref processor
2382 _ref_processor_stw =
2383 new ReferenceProcessor(mr, // span
2384 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2385 // mt processing
2386 ParallelGCThreads,
2387 // degree of mt processing
2388 (ParallelGCThreads > 1),
2389 // mt discovery
2390 ParallelGCThreads,
2391 // degree of mt discovery
2392 true,
2393 // Reference discovery is atomic
2394 &_is_alive_closure_stw);
2395 // is alive closure
2396 // (for efficiency/performance)
2397 }
2398
2399 size_t G1CollectedHeap::capacity() const {
2400 return _hrm.length() * HeapRegion::GrainBytes;
2401 }
2402
2403 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2404 assert(!hr->is_continues_humongous(), "pre-condition");
2405 hr->reset_gc_time_stamp();
2406 if (hr->is_starts_humongous()) {
2407 uint first_index = hr->hrm_index() + 1;
2408 uint last_index = hr->last_hc_index();
2409 for (uint i = first_index; i < last_index; i += 1) {
2410 HeapRegion* chr = region_at(i);
2411 assert(chr->is_continues_humongous(), "sanity");
2412 chr->reset_gc_time_stamp();
2413 }
2414 }
2415 }
2416
2417 #ifndef PRODUCT
2418
2419 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2420 private:
2421 unsigned _gc_time_stamp;
2422 bool _failures;
2423
2424 public:
2425 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2426 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2427
2428 virtual bool doHeapRegion(HeapRegion* hr) {
2429 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2430 if (_gc_time_stamp != region_gc_time_stamp) {
2431 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2432 "expected %d", HR_FORMAT_PARAMS(hr),
2433 region_gc_time_stamp, _gc_time_stamp);
2434 _failures = true;
2435 }
2436 return false;
2437 }
2438
2439 bool failures() { return _failures; }
2440 };
2441
2442 void G1CollectedHeap::check_gc_time_stamps() {
2443 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2444 heap_region_iterate(&cl);
2445 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2446 }
2447 #endif // PRODUCT
2448
2449 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2450 DirtyCardQueue* into_cset_dcq,
2451 bool concurrent,
2452 uint worker_i) {
2453 // Clean cards in the hot card cache
2454 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2455 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2456
2457 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2458 size_t n_completed_buffers = 0;
2459 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2460 n_completed_buffers++;
2461 }
2462 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2463 dcqs.clear_n_completed_buffers();
2464 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2465 }
2466
2467 // Computes the sum of the storage used by the various regions.
2468 size_t G1CollectedHeap::used() const {
2469 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2470 if (_archive_allocator != NULL) {
2471 result += _archive_allocator->used();
2472 }
2473 return result;
2474 }
2475
2476 size_t G1CollectedHeap::used_unlocked() const {
2477 return _summary_bytes_used;
2478 }
2479
2480 class SumUsedClosure: public HeapRegionClosure {
2481 size_t _used;
2482 public:
2483 SumUsedClosure() : _used(0) {}
2484 bool doHeapRegion(HeapRegion* r) {
2485 if (!r->is_continues_humongous()) {
2486 _used += r->used();
2487 }
2488 return false;
2489 }
2490 size_t result() { return _used; }
2491 };
2492
2493 size_t G1CollectedHeap::recalculate_used() const {
2494 double recalculate_used_start = os::elapsedTime();
2495
2496 SumUsedClosure blk;
2497 heap_region_iterate(&blk);
2498
2499 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2500 return blk.result();
2501 }
2502
2503 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2504 switch (cause) {
2505 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2506 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2507 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2508 case GCCause::_g1_humongous_allocation: return true;
2509 case GCCause::_update_allocation_context_stats_inc: return true;
2510 case GCCause::_wb_conc_mark: return true;
2511 default: return false;
2512 }
2513 }
2514
2515 #ifndef PRODUCT
2516 void G1CollectedHeap::allocate_dummy_regions() {
2517 // Let's fill up most of the region
2518 size_t word_size = HeapRegion::GrainWords - 1024;
2519 // And as a result the region we'll allocate will be humongous.
2520 guarantee(is_humongous(word_size), "sanity");
2521
2522 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2523 // Let's use the existing mechanism for the allocation
2524 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2525 AllocationContext::system());
2526 if (dummy_obj != NULL) {
2527 MemRegion mr(dummy_obj, word_size);
2528 CollectedHeap::fill_with_object(mr);
2529 } else {
2530 // If we can't allocate once, we probably cannot allocate
2531 // again. Let's get out of the loop.
2532 break;
2533 }
2534 }
2535 }
2536 #endif // !PRODUCT
2537
2538 void G1CollectedHeap::increment_old_marking_cycles_started() {
2539 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2540 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2541 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2542 _old_marking_cycles_started, _old_marking_cycles_completed));
2543
2544 _old_marking_cycles_started++;
2545 }
2546
2547 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2548 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2549
2550 // We assume that if concurrent == true, then the caller is a
2551 // concurrent thread that was joined the Suspendible Thread
2552 // Set. If there's ever a cheap way to check this, we should add an
2553 // assert here.
2554
2555 // Given that this method is called at the end of a Full GC or of a
2556 // concurrent cycle, and those can be nested (i.e., a Full GC can
2557 // interrupt a concurrent cycle), the number of full collections
2558 // completed should be either one (in the case where there was no
2559 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2560 // behind the number of full collections started.
2561
2562 // This is the case for the inner caller, i.e. a Full GC.
2563 assert(concurrent ||
2564 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2565 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2566 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2567 "is inconsistent with _old_marking_cycles_completed = %u",
2568 _old_marking_cycles_started, _old_marking_cycles_completed));
2569
2570 // This is the case for the outer caller, i.e. the concurrent cycle.
2571 assert(!concurrent ||
2572 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2573 err_msg("for outer caller (concurrent cycle): "
2574 "_old_marking_cycles_started = %u "
2575 "is inconsistent with _old_marking_cycles_completed = %u",
2576 _old_marking_cycles_started, _old_marking_cycles_completed));
2577
2578 _old_marking_cycles_completed += 1;
2579
2580 // We need to clear the "in_progress" flag in the CM thread before
2581 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2582 // is set) so that if a waiter requests another System.gc() it doesn't
2583 // incorrectly see that a marking cycle is still in progress.
2584 if (concurrent) {
2585 _cmThread->set_idle();
2586 }
2587
2588 // This notify_all() will ensure that a thread that called
2589 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2590 // and it's waiting for a full GC to finish will be woken up. It is
2591 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2592 FullGCCount_lock->notify_all();
2593 }
2594
2595 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2596 collector_state()->set_concurrent_cycle_started(true);
2597 _gc_timer_cm->register_gc_start(start_time);
2598
2599 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2600 trace_heap_before_gc(_gc_tracer_cm);
2601 }
2602
2603 void G1CollectedHeap::register_concurrent_cycle_end() {
2604 if (collector_state()->concurrent_cycle_started()) {
2605 if (_cm->has_aborted()) {
2606 _gc_tracer_cm->report_concurrent_mode_failure();
2607 }
2608
2609 _gc_timer_cm->register_gc_end();
2610 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2611
2612 // Clear state variables to prepare for the next concurrent cycle.
2613 collector_state()->set_concurrent_cycle_started(false);
2614 _heap_summary_sent = false;
2615 }
2616 }
2617
2618 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2619 if (collector_state()->concurrent_cycle_started()) {
2620 // This function can be called when:
2621 // the cleanup pause is run
2622 // the concurrent cycle is aborted before the cleanup pause.
2623 // the concurrent cycle is aborted after the cleanup pause,
2624 // but before the concurrent cycle end has been registered.
2625 // Make sure that we only send the heap information once.
2626 if (!_heap_summary_sent) {
2627 trace_heap_after_gc(_gc_tracer_cm);
2628 _heap_summary_sent = true;
2629 }
2630 }
2631 }
2632
2633 void G1CollectedHeap::collect(GCCause::Cause cause) {
2634 assert_heap_not_locked();
2635
2636 uint gc_count_before;
2637 uint old_marking_count_before;
2638 uint full_gc_count_before;
2639 bool retry_gc;
2640
2641 do {
2642 retry_gc = false;
2643
2644 {
2645 MutexLocker ml(Heap_lock);
2646
2647 // Read the GC count while holding the Heap_lock
2648 gc_count_before = total_collections();
2649 full_gc_count_before = total_full_collections();
2650 old_marking_count_before = _old_marking_cycles_started;
2651 }
2652
2653 if (should_do_concurrent_full_gc(cause)) {
2654 // Schedule an initial-mark evacuation pause that will start a
2655 // concurrent cycle. We're setting word_size to 0 which means that
2656 // we are not requesting a post-GC allocation.
2657 VM_G1IncCollectionPause op(gc_count_before,
2658 0, /* word_size */
2659 true, /* should_initiate_conc_mark */
2660 g1_policy()->max_pause_time_ms(),
2661 cause);
2662 op.set_allocation_context(AllocationContext::current());
2663
2664 VMThread::execute(&op);
2665 if (!op.pause_succeeded()) {
2666 if (old_marking_count_before == _old_marking_cycles_started) {
2667 retry_gc = op.should_retry_gc();
2668 } else {
2669 // A Full GC happened while we were trying to schedule the
2670 // initial-mark GC. No point in starting a new cycle given
2671 // that the whole heap was collected anyway.
2672 }
2673
2674 if (retry_gc) {
2675 if (GC_locker::is_active_and_needs_gc()) {
2676 GC_locker::stall_until_clear();
2677 }
2678 }
2679 }
2680 } else {
2681 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2682 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2683
2684 // Schedule a standard evacuation pause. We're setting word_size
2685 // to 0 which means that we are not requesting a post-GC allocation.
2686 VM_G1IncCollectionPause op(gc_count_before,
2687 0, /* word_size */
2688 false, /* should_initiate_conc_mark */
2689 g1_policy()->max_pause_time_ms(),
2690 cause);
2691 VMThread::execute(&op);
2692 } else {
2693 // Schedule a Full GC.
2694 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2695 VMThread::execute(&op);
2696 }
2697 }
2698 } while (retry_gc);
2699 }
2700
2701 bool G1CollectedHeap::is_in(const void* p) const {
2702 if (_hrm.reserved().contains(p)) {
2703 // Given that we know that p is in the reserved space,
2704 // heap_region_containing_raw() should successfully
2705 // return the containing region.
2706 HeapRegion* hr = heap_region_containing_raw(p);
2707 return hr->is_in(p);
2708 } else {
2709 return false;
2710 }
2711 }
2712
2713 #ifdef ASSERT
2714 bool G1CollectedHeap::is_in_exact(const void* p) const {
2715 bool contains = reserved_region().contains(p);
2716 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2717 if (contains && available) {
2718 return true;
2719 } else {
2720 return false;
2721 }
2722 }
2723 #endif
2724
2725 bool G1CollectedHeap::obj_in_cs(oop obj) {
2726 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2727 return r != NULL && r->in_collection_set();
2728 }
2729
2730 // Iteration functions.
2731
2732 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2733
2734 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2735 ExtendedOopClosure* _cl;
2736 public:
2737 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2738 bool doHeapRegion(HeapRegion* r) {
2739 if (!r->is_continues_humongous()) {
2740 r->oop_iterate(_cl);
2741 }
2742 return false;
2743 }
2744 };
2745
2746 // Iterates an ObjectClosure over all objects within a HeapRegion.
2747
2748 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2749 ObjectClosure* _cl;
2750 public:
2751 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2752 bool doHeapRegion(HeapRegion* r) {
2753 if (!r->is_continues_humongous()) {
2754 r->object_iterate(_cl);
2755 }
2756 return false;
2757 }
2758 };
2759
2760 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2761 IterateObjectClosureRegionClosure blk(cl);
2762 heap_region_iterate(&blk);
2763 }
2764
2765 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2766 _hrm.iterate(cl);
2767 }
2768
2769 void
2770 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2771 uint worker_id,
2772 HeapRegionClaimer *hrclaimer,
2773 bool concurrent) const {
2774 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2775 }
2776
2777 // Clear the cached CSet starting regions and (more importantly)
2778 // the time stamps. Called when we reset the GC time stamp.
2779 void G1CollectedHeap::clear_cset_start_regions() {
2780 assert(_worker_cset_start_region != NULL, "sanity");
2781 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2782
2783 for (uint i = 0; i < ParallelGCThreads; i++) {
2784 _worker_cset_start_region[i] = NULL;
2785 _worker_cset_start_region_time_stamp[i] = 0;
2786 }
2787 }
2788
2789 // Given the id of a worker, obtain or calculate a suitable
2790 // starting region for iterating over the current collection set.
2791 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2792 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2793
2794 HeapRegion* result = NULL;
2795 unsigned gc_time_stamp = get_gc_time_stamp();
2796
2797 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2798 // Cached starting region for current worker was set
2799 // during the current pause - so it's valid.
2800 // Note: the cached starting heap region may be NULL
2801 // (when the collection set is empty).
2802 result = _worker_cset_start_region[worker_i];
2803 assert(result == NULL || result->in_collection_set(), "sanity");
2804 return result;
2805 }
2806
2807 // The cached entry was not valid so let's calculate
2808 // a suitable starting heap region for this worker.
2809
2810 // We want the parallel threads to start their collection
2811 // set iteration at different collection set regions to
2812 // avoid contention.
2813 // If we have:
2814 // n collection set regions
2815 // p threads
2816 // Then thread t will start at region floor ((t * n) / p)
2817
2818 result = g1_policy()->collection_set();
2819 uint cs_size = g1_policy()->cset_region_length();
2820 uint active_workers = workers()->active_workers();
2821
2822 uint end_ind = (cs_size * worker_i) / active_workers;
2823 uint start_ind = 0;
2824
2825 if (worker_i > 0 &&
2826 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2827 // Previous workers starting region is valid
2828 // so let's iterate from there
2829 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2830 result = _worker_cset_start_region[worker_i - 1];
2831 }
2832
2833 for (uint i = start_ind; i < end_ind; i++) {
2834 result = result->next_in_collection_set();
2835 }
2836
2837 // Note: the calculated starting heap region may be NULL
2838 // (when the collection set is empty).
2839 assert(result == NULL || result->in_collection_set(), "sanity");
2840 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2841 "should be updated only once per pause");
2842 _worker_cset_start_region[worker_i] = result;
2843 OrderAccess::storestore();
2844 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2845 return result;
2846 }
2847
2848 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2849 HeapRegion* r = g1_policy()->collection_set();
2850 while (r != NULL) {
2851 HeapRegion* next = r->next_in_collection_set();
2852 if (cl->doHeapRegion(r)) {
2853 cl->incomplete();
2854 return;
2855 }
2856 r = next;
2857 }
2858 }
2859
2860 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2861 HeapRegionClosure *cl) {
2862 if (r == NULL) {
2863 // The CSet is empty so there's nothing to do.
2864 return;
2865 }
2866
2867 assert(r->in_collection_set(),
2868 "Start region must be a member of the collection set.");
2869 HeapRegion* cur = r;
2870 while (cur != NULL) {
2871 HeapRegion* next = cur->next_in_collection_set();
2872 if (cl->doHeapRegion(cur) && false) {
2873 cl->incomplete();
2874 return;
2875 }
2876 cur = next;
2877 }
2878 cur = g1_policy()->collection_set();
2879 while (cur != r) {
2880 HeapRegion* next = cur->next_in_collection_set();
2881 if (cl->doHeapRegion(cur) && false) {
2882 cl->incomplete();
2883 return;
2884 }
2885 cur = next;
2886 }
2887 }
2888
2889 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2890 HeapRegion* result = _hrm.next_region_in_heap(from);
2891 while (result != NULL && result->is_pinned()) {
2892 result = _hrm.next_region_in_heap(result);
2893 }
2894 return result;
2895 }
2896
2897 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2898 HeapRegion* hr = heap_region_containing(addr);
2899 return hr->block_start(addr);
2900 }
2901
2902 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2903 HeapRegion* hr = heap_region_containing(addr);
2904 return hr->block_size(addr);
2905 }
2906
2907 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2908 HeapRegion* hr = heap_region_containing(addr);
2909 return hr->block_is_obj(addr);
2910 }
2911
2912 bool G1CollectedHeap::supports_tlab_allocation() const {
2913 return true;
2914 }
2915
2916 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2917 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2918 }
2919
2920 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2921 return young_list()->eden_used_bytes();
2922 }
2923
2924 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2925 // must be equal to the humongous object limit.
2926 size_t G1CollectedHeap::max_tlab_size() const {
2927 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2928 }
2929
2930 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2931 AllocationContext_t context = AllocationContext::current();
2932 return _allocator->unsafe_max_tlab_alloc(context);
2933 }
2934
2935 size_t G1CollectedHeap::max_capacity() const {
2936 return _hrm.reserved().byte_size();
2937 }
2938
2939 jlong G1CollectedHeap::millis_since_last_gc() {
2940 // assert(false, "NYI");
2941 return 0;
2942 }
2943
2944 void G1CollectedHeap::prepare_for_verify() {
2945 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2946 ensure_parsability(false);
2947 }
2948 g1_rem_set()->prepare_for_verify();
2949 }
2950
2951 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2952 VerifyOption vo) {
2953 switch (vo) {
2954 case VerifyOption_G1UsePrevMarking:
2955 return hr->obj_allocated_since_prev_marking(obj);
2956 case VerifyOption_G1UseNextMarking:
2957 return hr->obj_allocated_since_next_marking(obj);
2958 case VerifyOption_G1UseMarkWord:
2959 return false;
2960 default:
2961 ShouldNotReachHere();
2962 }
2963 return false; // keep some compilers happy
2964 }
2965
2966 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2967 switch (vo) {
2968 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2969 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2970 case VerifyOption_G1UseMarkWord: return NULL;
2971 default: ShouldNotReachHere();
2972 }
2973 return NULL; // keep some compilers happy
2974 }
2975
2976 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2977 switch (vo) {
2978 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2979 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2980 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2981 default: ShouldNotReachHere();
2982 }
2983 return false; // keep some compilers happy
2984 }
2985
2986 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2987 switch (vo) {
2988 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2989 case VerifyOption_G1UseNextMarking: return "NTAMS";
2990 case VerifyOption_G1UseMarkWord: return "NONE";
2991 default: ShouldNotReachHere();
2992 }
2993 return NULL; // keep some compilers happy
2994 }
2995
2996 class VerifyRootsClosure: public OopClosure {
2997 private:
2998 G1CollectedHeap* _g1h;
2999 VerifyOption _vo;
3000 bool _failures;
3001 public:
3002 // _vo == UsePrevMarking -> use "prev" marking information,
3003 // _vo == UseNextMarking -> use "next" marking information,
3004 // _vo == UseMarkWord -> use mark word from object header.
3005 VerifyRootsClosure(VerifyOption vo) :
3006 _g1h(G1CollectedHeap::heap()),
3007 _vo(vo),
3008 _failures(false) { }
3009
3010 bool failures() { return _failures; }
3011
3012 template <class T> void do_oop_nv(T* p) {
3013 T heap_oop = oopDesc::load_heap_oop(p);
3014 if (!oopDesc::is_null(heap_oop)) {
3015 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3016 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3017 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3018 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3019 if (_vo == VerifyOption_G1UseMarkWord) {
3020 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3021 }
3022 obj->print_on(gclog_or_tty);
3023 _failures = true;
3024 }
3025 }
3026 }
3027
3028 void do_oop(oop* p) { do_oop_nv(p); }
3029 void do_oop(narrowOop* p) { do_oop_nv(p); }
3030 };
3031
3032 class G1VerifyCodeRootOopClosure: public OopClosure {
3033 G1CollectedHeap* _g1h;
3034 OopClosure* _root_cl;
3035 nmethod* _nm;
3036 VerifyOption _vo;
3037 bool _failures;
3038
3039 template <class T> void do_oop_work(T* p) {
3040 // First verify that this root is live
3041 _root_cl->do_oop(p);
3042
3043 if (!G1VerifyHeapRegionCodeRoots) {
3044 // We're not verifying the code roots attached to heap region.
3045 return;
3046 }
3047
3048 // Don't check the code roots during marking verification in a full GC
3049 if (_vo == VerifyOption_G1UseMarkWord) {
3050 return;
3051 }
3052
3053 // Now verify that the current nmethod (which contains p) is
3054 // in the code root list of the heap region containing the
3055 // object referenced by p.
3056
3057 T heap_oop = oopDesc::load_heap_oop(p);
3058 if (!oopDesc::is_null(heap_oop)) {
3059 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3060
3061 // Now fetch the region containing the object
3062 HeapRegion* hr = _g1h->heap_region_containing(obj);
3063 HeapRegionRemSet* hrrs = hr->rem_set();
3064 // Verify that the strong code root list for this region
3065 // contains the nmethod
3066 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3067 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3068 "from nmethod " PTR_FORMAT " not in strong "
3069 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3070 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3071 _failures = true;
3072 }
3073 }
3074 }
3075
3076 public:
3077 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3078 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3079
3080 void do_oop(oop* p) { do_oop_work(p); }
3081 void do_oop(narrowOop* p) { do_oop_work(p); }
3082
3083 void set_nmethod(nmethod* nm) { _nm = nm; }
3084 bool failures() { return _failures; }
3085 };
3086
3087 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3088 G1VerifyCodeRootOopClosure* _oop_cl;
3089
3090 public:
3091 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3092 _oop_cl(oop_cl) {}
3093
3094 void do_code_blob(CodeBlob* cb) {
3095 nmethod* nm = cb->as_nmethod_or_null();
3096 if (nm != NULL) {
3097 _oop_cl->set_nmethod(nm);
3098 nm->oops_do(_oop_cl);
3099 }
3100 }
3101 };
3102
3103 class YoungRefCounterClosure : public OopClosure {
3104 G1CollectedHeap* _g1h;
3105 int _count;
3106 public:
3107 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3108 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3109 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3110
3111 int count() { return _count; }
3112 void reset_count() { _count = 0; };
3113 };
3114
3115 class VerifyKlassClosure: public KlassClosure {
3116 YoungRefCounterClosure _young_ref_counter_closure;
3117 OopClosure *_oop_closure;
3118 public:
3119 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3120 void do_klass(Klass* k) {
3121 k->oops_do(_oop_closure);
3122
3123 _young_ref_counter_closure.reset_count();
3124 k->oops_do(&_young_ref_counter_closure);
3125 if (_young_ref_counter_closure.count() > 0) {
3126 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3127 }
3128 }
3129 };
3130
3131 class VerifyLivenessOopClosure: public OopClosure {
3132 G1CollectedHeap* _g1h;
3133 VerifyOption _vo;
3134 public:
3135 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3136 _g1h(g1h), _vo(vo)
3137 { }
3138 void do_oop(narrowOop *p) { do_oop_work(p); }
3139 void do_oop( oop *p) { do_oop_work(p); }
3140
3141 template <class T> void do_oop_work(T *p) {
3142 oop obj = oopDesc::load_decode_heap_oop(p);
3143 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3144 "Dead object referenced by a not dead object");
3145 }
3146 };
3147
3148 class VerifyObjsInRegionClosure: public ObjectClosure {
3149 private:
3150 G1CollectedHeap* _g1h;
3151 size_t _live_bytes;
3152 HeapRegion *_hr;
3153 VerifyOption _vo;
3154 public:
3155 // _vo == UsePrevMarking -> use "prev" marking information,
3156 // _vo == UseNextMarking -> use "next" marking information,
3157 // _vo == UseMarkWord -> use mark word from object header.
3158 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3159 : _live_bytes(0), _hr(hr), _vo(vo) {
3160 _g1h = G1CollectedHeap::heap();
3161 }
3162 void do_object(oop o) {
3163 VerifyLivenessOopClosure isLive(_g1h, _vo);
3164 assert(o != NULL, "Huh?");
3165 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3166 // If the object is alive according to the mark word,
3167 // then verify that the marking information agrees.
3168 // Note we can't verify the contra-positive of the
3169 // above: if the object is dead (according to the mark
3170 // word), it may not be marked, or may have been marked
3171 // but has since became dead, or may have been allocated
3172 // since the last marking.
3173 if (_vo == VerifyOption_G1UseMarkWord) {
3174 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3175 }
3176
3177 o->oop_iterate_no_header(&isLive);
3178 if (!_hr->obj_allocated_since_prev_marking(o)) {
3179 size_t obj_size = o->size(); // Make sure we don't overflow
3180 _live_bytes += (obj_size * HeapWordSize);
3181 }
3182 }
3183 }
3184 size_t live_bytes() { return _live_bytes; }
3185 };
3186
3187 class VerifyArchiveOopClosure: public OopClosure {
3188 public:
3189 VerifyArchiveOopClosure(HeapRegion *hr) { }
3190 void do_oop(narrowOop *p) { do_oop_work(p); }
3191 void do_oop( oop *p) { do_oop_work(p); }
3192
3193 template <class T> void do_oop_work(T *p) {
3194 oop obj = oopDesc::load_decode_heap_oop(p);
3195 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3196 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3197 p2i(p), p2i(obj)));
3198 }
3199 };
3200
3201 class VerifyArchiveRegionClosure: public ObjectClosure {
3202 public:
3203 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3204 // Verify that all object pointers are to archive regions.
3205 void do_object(oop o) {
3206 VerifyArchiveOopClosure checkOop(NULL);
3207 assert(o != NULL, "Should not be here for NULL oops");
3208 o->oop_iterate_no_header(&checkOop);
3209 }
3210 };
3211
3212 class VerifyRegionClosure: public HeapRegionClosure {
3213 private:
3214 bool _par;
3215 VerifyOption _vo;
3216 bool _failures;
3217 public:
3218 // _vo == UsePrevMarking -> use "prev" marking information,
3219 // _vo == UseNextMarking -> use "next" marking information,
3220 // _vo == UseMarkWord -> use mark word from object header.
3221 VerifyRegionClosure(bool par, VerifyOption vo)
3222 : _par(par),
3223 _vo(vo),
3224 _failures(false) {}
3225
3226 bool failures() {
3227 return _failures;
3228 }
3229
3230 bool doHeapRegion(HeapRegion* r) {
3231 // For archive regions, verify there are no heap pointers to
3232 // non-pinned regions. For all others, verify liveness info.
3233 if (r->is_archive()) {
3234 VerifyArchiveRegionClosure verify_oop_pointers(r);
3235 r->object_iterate(&verify_oop_pointers);
3236 return true;
3237 }
3238 if (!r->is_continues_humongous()) {
3239 bool failures = false;
3240 r->verify(_vo, &failures);
3241 if (failures) {
3242 _failures = true;
3243 } else {
3244 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3245 r->object_iterate(¬_dead_yet_cl);
3246 if (_vo != VerifyOption_G1UseNextMarking) {
3247 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3248 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3249 "max_live_bytes " SIZE_FORMAT " "
3250 "< calculated " SIZE_FORMAT,
3251 p2i(r->bottom()), p2i(r->end()),
3252 r->max_live_bytes(),
3253 not_dead_yet_cl.live_bytes());
3254 _failures = true;
3255 }
3256 } else {
3257 // When vo == UseNextMarking we cannot currently do a sanity
3258 // check on the live bytes as the calculation has not been
3259 // finalized yet.
3260 }
3261 }
3262 }
3263 return false; // stop the region iteration if we hit a failure
3264 }
3265 };
3266
3267 // This is the task used for parallel verification of the heap regions
3268
3269 class G1ParVerifyTask: public AbstractGangTask {
3270 private:
3271 G1CollectedHeap* _g1h;
3272 VerifyOption _vo;
3273 bool _failures;
3274 HeapRegionClaimer _hrclaimer;
3275
3276 public:
3277 // _vo == UsePrevMarking -> use "prev" marking information,
3278 // _vo == UseNextMarking -> use "next" marking information,
3279 // _vo == UseMarkWord -> use mark word from object header.
3280 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3281 AbstractGangTask("Parallel verify task"),
3282 _g1h(g1h),
3283 _vo(vo),
3284 _failures(false),
3285 _hrclaimer(g1h->workers()->active_workers()) {}
3286
3287 bool failures() {
3288 return _failures;
3289 }
3290
3291 void work(uint worker_id) {
3292 HandleMark hm;
3293 VerifyRegionClosure blk(true, _vo);
3294 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3295 if (blk.failures()) {
3296 _failures = true;
3297 }
3298 }
3299 };
3300
3301 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3302 if (SafepointSynchronize::is_at_safepoint()) {
3303 assert(Thread::current()->is_VM_thread(),
3304 "Expected to be executed serially by the VM thread at this point");
3305
3306 if (!silent) { gclog_or_tty->print("Roots "); }
3307 VerifyRootsClosure rootsCl(vo);
3308 VerifyKlassClosure klassCl(this, &rootsCl);
3309 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3310
3311 // We apply the relevant closures to all the oops in the
3312 // system dictionary, class loader data graph, the string table
3313 // and the nmethods in the code cache.
3314 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3315 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3316
3317 {
3318 G1RootProcessor root_processor(this, 1);
3319 root_processor.process_all_roots(&rootsCl,
3320 &cldCl,
3321 &blobsCl);
3322 }
3323
3324 bool failures = rootsCl.failures() || codeRootsCl.failures();
3325
3326 if (vo != VerifyOption_G1UseMarkWord) {
3327 // If we're verifying during a full GC then the region sets
3328 // will have been torn down at the start of the GC. Therefore
3329 // verifying the region sets will fail. So we only verify
3330 // the region sets when not in a full GC.
3331 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3332 verify_region_sets();
3333 }
3334
3335 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3336 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3337
3338 G1ParVerifyTask task(this, vo);
3339 workers()->run_task(&task);
3340 if (task.failures()) {
3341 failures = true;
3342 }
3343
3344 } else {
3345 VerifyRegionClosure blk(false, vo);
3346 heap_region_iterate(&blk);
3347 if (blk.failures()) {
3348 failures = true;
3349 }
3350 }
3351
3352 if (G1StringDedup::is_enabled()) {
3353 if (!silent) gclog_or_tty->print("StrDedup ");
3354 G1StringDedup::verify();
3355 }
3356
3357 if (failures) {
3358 gclog_or_tty->print_cr("Heap:");
3359 // It helps to have the per-region information in the output to
3360 // help us track down what went wrong. This is why we call
3361 // print_extended_on() instead of print_on().
3362 print_extended_on(gclog_or_tty);
3363 gclog_or_tty->cr();
3364 gclog_or_tty->flush();
3365 }
3366 guarantee(!failures, "there should not have been any failures");
3367 } else {
3368 if (!silent) {
3369 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3370 if (G1StringDedup::is_enabled()) {
3371 gclog_or_tty->print(", StrDedup");
3372 }
3373 gclog_or_tty->print(") ");
3374 }
3375 }
3376 }
3377
3378 void G1CollectedHeap::verify(bool silent) {
3379 verify(silent, VerifyOption_G1UsePrevMarking);
3380 }
3381
3382 double G1CollectedHeap::verify(bool guard, const char* msg) {
3383 double verify_time_ms = 0.0;
3384
3385 if (guard && total_collections() >= VerifyGCStartAt) {
3386 double verify_start = os::elapsedTime();
3387 HandleMark hm; // Discard invalid handles created during verification
3388 prepare_for_verify();
3389 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3390 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3391 }
3392
3393 return verify_time_ms;
3394 }
3395
3396 void G1CollectedHeap::verify_before_gc() {
3397 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3398 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3399 }
3400
3401 void G1CollectedHeap::verify_after_gc() {
3402 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3403 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3404 }
3405
3406 class PrintRegionClosure: public HeapRegionClosure {
3407 outputStream* _st;
3408 public:
3409 PrintRegionClosure(outputStream* st) : _st(st) {}
3410 bool doHeapRegion(HeapRegion* r) {
3411 r->print_on(_st);
3412 return false;
3413 }
3414 };
3415
3416 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3417 const HeapRegion* hr,
3418 const VerifyOption vo) const {
3419 switch (vo) {
3420 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3421 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3422 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3423 default: ShouldNotReachHere();
3424 }
3425 return false; // keep some compilers happy
3426 }
3427
3428 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3429 const VerifyOption vo) const {
3430 switch (vo) {
3431 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3432 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3433 case VerifyOption_G1UseMarkWord: {
3434 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3435 return !obj->is_gc_marked() && !hr->is_archive();
3436 }
3437 default: ShouldNotReachHere();
3438 }
3439 return false; // keep some compilers happy
3440 }
3441
3442 void G1CollectedHeap::print_on(outputStream* st) const {
3443 st->print(" %-20s", "garbage-first heap");
3444 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3445 capacity()/K, used_unlocked()/K);
3446 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3447 p2i(_hrm.reserved().start()),
3448 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3449 p2i(_hrm.reserved().end()));
3450 st->cr();
3451 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3452 uint young_regions = _young_list->length();
3453 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3454 (size_t) young_regions * HeapRegion::GrainBytes / K);
3455 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3456 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3457 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3458 st->cr();
3459 MetaspaceAux::print_on(st);
3460 }
3461
3462 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3463 print_on(st);
3464
3465 // Print the per-region information.
3466 st->cr();
3467 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3468 "HS=humongous(starts), HC=humongous(continues), "
3469 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3470 "PTAMS=previous top-at-mark-start, "
3471 "NTAMS=next top-at-mark-start)");
3472 PrintRegionClosure blk(st);
3473 heap_region_iterate(&blk);
3474 }
3475
3476 void G1CollectedHeap::print_on_error(outputStream* st) const {
3477 this->CollectedHeap::print_on_error(st);
3478
3479 if (_cm != NULL) {
3480 st->cr();
3481 _cm->print_on_error(st);
3482 }
3483 }
3484
3485 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3486 workers()->print_worker_threads_on(st);
3487 _cmThread->print_on(st);
3488 st->cr();
3489 _cm->print_worker_threads_on(st);
3490 _cg1r->print_worker_threads_on(st);
3491 if (G1StringDedup::is_enabled()) {
3492 G1StringDedup::print_worker_threads_on(st);
3493 }
3494 }
3495
3496 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3497 workers()->threads_do(tc);
3498 tc->do_thread(_cmThread);
3499 _cg1r->threads_do(tc);
3500 if (G1StringDedup::is_enabled()) {
3501 G1StringDedup::threads_do(tc);
3502 }
3503 }
3504
3505 void G1CollectedHeap::print_tracing_info() const {
3506 // We'll overload this to mean "trace GC pause statistics."
3507 if (TraceYoungGenTime || TraceOldGenTime) {
3508 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3509 // to that.
3510 g1_policy()->print_tracing_info();
3511 }
3512 if (G1SummarizeRSetStats) {
3513 g1_rem_set()->print_summary_info();
3514 }
3515 if (G1SummarizeConcMark) {
3516 concurrent_mark()->print_summary_info();
3517 }
3518 g1_policy()->print_yg_surv_rate_info();
3519 }
3520
3521 #ifndef PRODUCT
3522 // Helpful for debugging RSet issues.
3523
3524 class PrintRSetsClosure : public HeapRegionClosure {
3525 private:
3526 const char* _msg;
3527 size_t _occupied_sum;
3528
3529 public:
3530 bool doHeapRegion(HeapRegion* r) {
3531 HeapRegionRemSet* hrrs = r->rem_set();
3532 size_t occupied = hrrs->occupied();
3533 _occupied_sum += occupied;
3534
3535 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3536 HR_FORMAT_PARAMS(r));
3537 if (occupied == 0) {
3538 gclog_or_tty->print_cr(" RSet is empty");
3539 } else {
3540 hrrs->print();
3541 }
3542 gclog_or_tty->print_cr("----------");
3543 return false;
3544 }
3545
3546 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3547 gclog_or_tty->cr();
3548 gclog_or_tty->print_cr("========================================");
3549 gclog_or_tty->print_cr("%s", msg);
3550 gclog_or_tty->cr();
3551 }
3552
3553 ~PrintRSetsClosure() {
3554 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3555 gclog_or_tty->print_cr("========================================");
3556 gclog_or_tty->cr();
3557 }
3558 };
3559
3560 void G1CollectedHeap::print_cset_rsets() {
3561 PrintRSetsClosure cl("Printing CSet RSets");
3562 collection_set_iterate(&cl);
3563 }
3564
3565 void G1CollectedHeap::print_all_rsets() {
3566 PrintRSetsClosure cl("Printing All RSets");;
3567 heap_region_iterate(&cl);
3568 }
3569 #endif // PRODUCT
3570
3571 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3572 YoungList* young_list = heap()->young_list();
3573
3574 size_t eden_used_bytes = young_list->eden_used_bytes();
3575 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3576
3577 size_t eden_capacity_bytes =
3578 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3579
3580 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3581 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3582 }
3583
3584 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3585 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3586 stats->unused(), stats->used(), stats->region_end_waste(),
3587 stats->regions_filled(), stats->direct_allocated(),
3588 stats->failure_used(), stats->failure_waste());
3589 }
3590
3591 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3592 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3593 gc_tracer->report_gc_heap_summary(when, heap_summary);
3594
3595 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3596 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3597 }
3598
3599
3600 G1CollectedHeap* G1CollectedHeap::heap() {
3601 CollectedHeap* heap = Universe::heap();
3602 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3603 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3604 return (G1CollectedHeap*)heap;
3605 }
3606
3607 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3608 // always_do_update_barrier = false;
3609 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3610 // Fill TLAB's and such
3611 accumulate_statistics_all_tlabs();
3612 ensure_parsability(true);
3613
3614 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3615 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3616 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3617 }
3618 }
3619
3620 void G1CollectedHeap::gc_epilogue(bool full) {
3621
3622 if (G1SummarizeRSetStats &&
3623 (G1SummarizeRSetStatsPeriod > 0) &&
3624 // we are at the end of the GC. Total collections has already been increased.
3625 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3626 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3627 }
3628
3629 // FIXME: what is this about?
3630 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3631 // is set.
3632 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3633 "derived pointer present"));
3634 // always_do_update_barrier = true;
3635
3636 resize_all_tlabs();
3637 allocation_context_stats().update(full);
3638
3639 // We have just completed a GC. Update the soft reference
3640 // policy with the new heap occupancy
3641 Universe::update_heap_info_at_gc();
3642 }
3643
3644 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3645 uint gc_count_before,
3646 bool* succeeded,
3647 GCCause::Cause gc_cause) {
3648 assert_heap_not_locked_and_not_at_safepoint();
3649 g1_policy()->record_stop_world_start();
3650 VM_G1IncCollectionPause op(gc_count_before,
3651 word_size,
3652 false, /* should_initiate_conc_mark */
3653 g1_policy()->max_pause_time_ms(),
3654 gc_cause);
3655
3656 op.set_allocation_context(AllocationContext::current());
3657 VMThread::execute(&op);
3658
3659 HeapWord* result = op.result();
3660 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3661 assert(result == NULL || ret_succeeded,
3662 "the result should be NULL if the VM did not succeed");
3663 *succeeded = ret_succeeded;
3664
3665 assert_heap_not_locked();
3666 return result;
3667 }
3668
3669 void
3670 G1CollectedHeap::doConcurrentMark() {
3671 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3672 if (!_cmThread->in_progress()) {
3673 _cmThread->set_started();
3674 CGC_lock->notify();
3675 }
3676 }
3677
3678 size_t G1CollectedHeap::pending_card_num() {
3679 size_t extra_cards = 0;
3680 JavaThread *curr = Threads::first();
3681 while (curr != NULL) {
3682 DirtyCardQueue& dcq = curr->dirty_card_queue();
3683 extra_cards += dcq.size();
3684 curr = curr->next();
3685 }
3686 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3687 size_t buffer_size = dcqs.buffer_size();
3688 size_t buffer_num = dcqs.completed_buffers_num();
3689
3690 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3691 // in bytes - not the number of 'entries'. We need to convert
3692 // into a number of cards.
3693 return (buffer_size * buffer_num + extra_cards) / oopSize;
3694 }
3695
3696 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3697 private:
3698 size_t _total_humongous;
3699 size_t _candidate_humongous;
3700
3701 DirtyCardQueue _dcq;
3702
3703 // We don't nominate objects with many remembered set entries, on
3704 // the assumption that such objects are likely still live.
3705 bool is_remset_small(HeapRegion* region) const {
3706 HeapRegionRemSet* const rset = region->rem_set();
3707 return G1EagerReclaimHumongousObjectsWithStaleRefs
3708 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3709 : rset->is_empty();
3710 }
3711
3712 bool is_typeArray_region(HeapRegion* region) const {
3713 return oop(region->bottom())->is_typeArray();
3714 }
3715
3716 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3717 assert(region->is_starts_humongous(), "Must start a humongous object");
3718
3719 // Candidate selection must satisfy the following constraints
3720 // while concurrent marking is in progress:
3721 //
3722 // * In order to maintain SATB invariants, an object must not be
3723 // reclaimed if it was allocated before the start of marking and
3724 // has not had its references scanned. Such an object must have
3725 // its references (including type metadata) scanned to ensure no
3726 // live objects are missed by the marking process. Objects
3727 // allocated after the start of concurrent marking don't need to
3728 // be scanned.
3729 //
3730 // * An object must not be reclaimed if it is on the concurrent
3731 // mark stack. Objects allocated after the start of concurrent
3732 // marking are never pushed on the mark stack.
3733 //
3734 // Nominating only objects allocated after the start of concurrent
3735 // marking is sufficient to meet both constraints. This may miss
3736 // some objects that satisfy the constraints, but the marking data
3737 // structures don't support efficiently performing the needed
3738 // additional tests or scrubbing of the mark stack.
3739 //
3740 // However, we presently only nominate is_typeArray() objects.
3741 // A humongous object containing references induces remembered
3742 // set entries on other regions. In order to reclaim such an
3743 // object, those remembered sets would need to be cleaned up.
3744 //
3745 // We also treat is_typeArray() objects specially, allowing them
3746 // to be reclaimed even if allocated before the start of
3747 // concurrent mark. For this we rely on mark stack insertion to
3748 // exclude is_typeArray() objects, preventing reclaiming an object
3749 // that is in the mark stack. We also rely on the metadata for
3750 // such objects to be built-in and so ensured to be kept live.
3751 // Frequent allocation and drop of large binary blobs is an
3752 // important use case for eager reclaim, and this special handling
3753 // may reduce needed headroom.
3754
3755 return is_typeArray_region(region) && is_remset_small(region);
3756 }
3757
3758 public:
3759 RegisterHumongousWithInCSetFastTestClosure()
3760 : _total_humongous(0),
3761 _candidate_humongous(0),
3762 _dcq(&JavaThread::dirty_card_queue_set()) {
3763 }
3764
3765 virtual bool doHeapRegion(HeapRegion* r) {
3766 if (!r->is_starts_humongous()) {
3767 return false;
3768 }
3769 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3770
3771 bool is_candidate = humongous_region_is_candidate(g1h, r);
3772 uint rindex = r->hrm_index();
3773 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3774 if (is_candidate) {
3775 _candidate_humongous++;
3776 g1h->register_humongous_region_with_cset(rindex);
3777 // Is_candidate already filters out humongous object with large remembered sets.
3778 // If we have a humongous object with a few remembered sets, we simply flush these
3779 // remembered set entries into the DCQS. That will result in automatic
3780 // re-evaluation of their remembered set entries during the following evacuation
3781 // phase.
3782 if (!r->rem_set()->is_empty()) {
3783 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3784 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3785 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3786 HeapRegionRemSetIterator hrrs(r->rem_set());
3787 size_t card_index;
3788 while (hrrs.has_next(card_index)) {
3789 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3790 // The remembered set might contain references to already freed
3791 // regions. Filter out such entries to avoid failing card table
3792 // verification.
3793 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3794 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3795 *card_ptr = CardTableModRefBS::dirty_card_val();
3796 _dcq.enqueue(card_ptr);
3797 }
3798 }
3799 }
3800 r->rem_set()->clear_locked();
3801 }
3802 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3803 }
3804 _total_humongous++;
3805
3806 return false;
3807 }
3808
3809 size_t total_humongous() const { return _total_humongous; }
3810 size_t candidate_humongous() const { return _candidate_humongous; }
3811
3812 void flush_rem_set_entries() { _dcq.flush(); }
3813 };
3814
3815 void G1CollectedHeap::register_humongous_regions_with_cset() {
3816 if (!G1EagerReclaimHumongousObjects) {
3817 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3818 return;
3819 }
3820 double time = os::elapsed_counter();
3821
3822 // Collect reclaim candidate information and register candidates with cset.
3823 RegisterHumongousWithInCSetFastTestClosure cl;
3824 heap_region_iterate(&cl);
3825
3826 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3827 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3828 cl.total_humongous(),
3829 cl.candidate_humongous());
3830 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3831
3832 // Finally flush all remembered set entries to re-check into the global DCQS.
3833 cl.flush_rem_set_entries();
3834 }
3835
3836 #ifdef ASSERT
3837 class VerifyCSetClosure: public HeapRegionClosure {
3838 public:
3839 bool doHeapRegion(HeapRegion* hr) {
3840 // Here we check that the CSet region's RSet is ready for parallel
3841 // iteration. The fields that we'll verify are only manipulated
3842 // when the region is part of a CSet and is collected. Afterwards,
3843 // we reset these fields when we clear the region's RSet (when the
3844 // region is freed) so they are ready when the region is
3845 // re-allocated. The only exception to this is if there's an
3846 // evacuation failure and instead of freeing the region we leave
3847 // it in the heap. In that case, we reset these fields during
3848 // evacuation failure handling.
3849 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3850
3851 // Here's a good place to add any other checks we'd like to
3852 // perform on CSet regions.
3853 return false;
3854 }
3855 };
3856 #endif // ASSERT
3857
3858 uint G1CollectedHeap::num_task_queues() const {
3859 return _task_queues->size();
3860 }
3861
3862 #if TASKQUEUE_STATS
3863 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3864 st->print_raw_cr("GC Task Stats");
3865 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3866 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3867 }
3868
3869 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3870 print_taskqueue_stats_hdr(st);
3871
3872 TaskQueueStats totals;
3873 const uint n = num_task_queues();
3874 for (uint i = 0; i < n; ++i) {
3875 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3876 totals += task_queue(i)->stats;
3877 }
3878 st->print_raw("tot "); totals.print(st); st->cr();
3879
3880 DEBUG_ONLY(totals.verify());
3881 }
3882
3883 void G1CollectedHeap::reset_taskqueue_stats() {
3884 const uint n = num_task_queues();
3885 for (uint i = 0; i < n; ++i) {
3886 task_queue(i)->stats.reset();
3887 }
3888 }
3889 #endif // TASKQUEUE_STATS
3890
3891 void G1CollectedHeap::log_gc_header() {
3892 if (!G1Log::fine()) {
3893 return;
3894 }
3895
3896 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3897
3898 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3899 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3900 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3901
3902 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3903 }
3904
3905 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3906 if (!G1Log::fine()) {
3907 return;
3908 }
3909
3910 if (G1Log::finer()) {
3911 if (evacuation_failed()) {
3912 gclog_or_tty->print(" (to-space exhausted)");
3913 }
3914 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3915 g1_policy()->phase_times()->note_gc_end();
3916 g1_policy()->phase_times()->print(pause_time_sec);
3917 g1_policy()->print_detailed_heap_transition();
3918 } else {
3919 if (evacuation_failed()) {
3920 gclog_or_tty->print("--");
3921 }
3922 g1_policy()->print_heap_transition();
3923 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3924 }
3925 gclog_or_tty->flush();
3926 }
3927
3928 void G1CollectedHeap::wait_for_root_region_scanning() {
3929 double scan_wait_start = os::elapsedTime();
3930 // We have to wait until the CM threads finish scanning the
3931 // root regions as it's the only way to ensure that all the
3932 // objects on them have been correctly scanned before we start
3933 // moving them during the GC.
3934 bool waited = _cm->root_regions()->wait_until_scan_finished();
3935 double wait_time_ms = 0.0;
3936 if (waited) {
3937 double scan_wait_end = os::elapsedTime();
3938 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3939 }
3940 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3941 }
3942
3943 bool
3944 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3945 assert_at_safepoint(true /* should_be_vm_thread */);
3946 guarantee(!is_gc_active(), "collection is not reentrant");
3947
3948 if (GC_locker::check_active_before_gc()) {
3949 return false;
3950 }
3951
3952 _gc_timer_stw->register_gc_start();
3953
3954 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3955
3956 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3957 ResourceMark rm;
3958
3959 wait_for_root_region_scanning();
3960
3961 G1Log::update_level();
3962 print_heap_before_gc();
3963 trace_heap_before_gc(_gc_tracer_stw);
3964
3965 verify_region_sets_optional();
3966 verify_dirty_young_regions();
3967
3968 // This call will decide whether this pause is an initial-mark
3969 // pause. If it is, during_initial_mark_pause() will return true
3970 // for the duration of this pause.
3971 g1_policy()->decide_on_conc_mark_initiation();
3972
3973 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3974 assert(!collector_state()->during_initial_mark_pause() ||
3975 collector_state()->gcs_are_young(), "sanity");
3976
3977 // We also do not allow mixed GCs during marking.
3978 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3979
3980 // Record whether this pause is an initial mark. When the current
3981 // thread has completed its logging output and it's safe to signal
3982 // the CM thread, the flag's value in the policy has been reset.
3983 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3984
3985 // Inner scope for scope based logging, timers, and stats collection
3986 {
3987 EvacuationInfo evacuation_info;
3988
3989 if (collector_state()->during_initial_mark_pause()) {
3990 // We are about to start a marking cycle, so we increment the
3991 // full collection counter.
3992 increment_old_marking_cycles_started();
3993 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3994 }
3995
3996 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3997
3998 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3999
4000 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4001 workers()->active_workers(),
4002 Threads::number_of_non_daemon_threads());
4003 workers()->set_active_workers(active_workers);
4004
4005 double pause_start_sec = os::elapsedTime();
4006 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4007 log_gc_header();
4008
4009 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4010 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4011
4012 // If the secondary_free_list is not empty, append it to the
4013 // free_list. No need to wait for the cleanup operation to finish;
4014 // the region allocation code will check the secondary_free_list
4015 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4016 // set, skip this step so that the region allocation code has to
4017 // get entries from the secondary_free_list.
4018 if (!G1StressConcRegionFreeing) {
4019 append_secondary_free_list_if_not_empty_with_lock();
4020 }
4021
4022 assert(check_young_list_well_formed(), "young list should be well formed");
4023
4024 // Don't dynamically change the number of GC threads this early. A value of
4025 // 0 is used to indicate serial work. When parallel work is done,
4026 // it will be set.
4027
4028 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4029 IsGCActiveMark x;
4030
4031 gc_prologue(false);
4032 increment_total_collections(false /* full gc */);
4033 increment_gc_time_stamp();
4034
4035 verify_before_gc();
4036
4037 check_bitmaps("GC Start");
4038
4039 COMPILER2_PRESENT(DerivedPointerTable::clear());
4040
4041 // Please see comment in g1CollectedHeap.hpp and
4042 // G1CollectedHeap::ref_processing_init() to see how
4043 // reference processing currently works in G1.
4044
4045 // Enable discovery in the STW reference processor
4046 ref_processor_stw()->enable_discovery();
4047
4048 {
4049 // We want to temporarily turn off discovery by the
4050 // CM ref processor, if necessary, and turn it back on
4051 // on again later if we do. Using a scoped
4052 // NoRefDiscovery object will do this.
4053 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4054
4055 // Forget the current alloc region (we might even choose it to be part
4056 // of the collection set!).
4057 _allocator->release_mutator_alloc_region();
4058
4059 // We should call this after we retire the mutator alloc
4060 // region(s) so that all the ALLOC / RETIRE events are generated
4061 // before the start GC event.
4062 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4063
4064 // This timing is only used by the ergonomics to handle our pause target.
4065 // It is unclear why this should not include the full pause. We will
4066 // investigate this in CR 7178365.
4067 //
4068 // Preserving the old comment here if that helps the investigation:
4069 //
4070 // The elapsed time induced by the start time below deliberately elides
4071 // the possible verification above.
4072 double sample_start_time_sec = os::elapsedTime();
4073
4074 #if YOUNG_LIST_VERBOSE
4075 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4076 _young_list->print();
4077 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4078 #endif // YOUNG_LIST_VERBOSE
4079
4080 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4081
4082 #if YOUNG_LIST_VERBOSE
4083 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4084 _young_list->print();
4085 #endif // YOUNG_LIST_VERBOSE
4086
4087 if (collector_state()->during_initial_mark_pause()) {
4088 concurrent_mark()->checkpointRootsInitialPre();
4089 }
4090
4091 #if YOUNG_LIST_VERBOSE
4092 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4093 _young_list->print();
4094 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4095 #endif // YOUNG_LIST_VERBOSE
4096
4097 g1_policy()->finalize_cset(target_pause_time_ms);
4098
4099 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4100
4101 register_humongous_regions_with_cset();
4102
4103 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4104
4105 _cm->note_start_of_gc();
4106 // We call this after finalize_cset() to
4107 // ensure that the CSet has been finalized.
4108 _cm->verify_no_cset_oops();
4109
4110 if (_hr_printer.is_active()) {
4111 HeapRegion* hr = g1_policy()->collection_set();
4112 while (hr != NULL) {
4113 _hr_printer.cset(hr);
4114 hr = hr->next_in_collection_set();
4115 }
4116 }
4117
4118 #ifdef ASSERT
4119 VerifyCSetClosure cl;
4120 collection_set_iterate(&cl);
4121 #endif // ASSERT
4122
4123 // Initialize the GC alloc regions.
4124 _allocator->init_gc_alloc_regions(evacuation_info);
4125
4126 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
4127 // Actually do the work...
4128 evacuate_collection_set(evacuation_info, &per_thread_states);
4129
4130 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
4131 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
4132
4133 eagerly_reclaim_humongous_regions();
4134
4135 g1_policy()->clear_collection_set();
4136
4137 // Start a new incremental collection set for the next pause.
4138 g1_policy()->start_incremental_cset_building();
4139
4140 clear_cset_fast_test();
4141
4142 _young_list->reset_sampled_info();
4143
4144 // Don't check the whole heap at this point as the
4145 // GC alloc regions from this pause have been tagged
4146 // as survivors and moved on to the survivor list.
4147 // Survivor regions will fail the !is_young() check.
4148 assert(check_young_list_empty(false /* check_heap */),
4149 "young list should be empty");
4150
4151 #if YOUNG_LIST_VERBOSE
4152 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4153 _young_list->print();
4154 #endif // YOUNG_LIST_VERBOSE
4155
4156 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4157 _young_list->first_survivor_region(),
4158 _young_list->last_survivor_region());
4159
4160 _young_list->reset_auxilary_lists();
4161
4162 if (evacuation_failed()) {
4163 set_used(recalculate_used());
4164 if (_archive_allocator != NULL) {
4165 _archive_allocator->clear_used();
4166 }
4167 for (uint i = 0; i < ParallelGCThreads; i++) {
4168 if (_evacuation_failed_info_array[i].has_failed()) {
4169 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4170 }
4171 }
4172 } else {
4173 // The "used" of the the collection set have already been subtracted
4174 // when they were freed. Add in the bytes evacuated.
4175 increase_used(g1_policy()->bytes_copied_during_gc());
4176 }
4177
4178 if (collector_state()->during_initial_mark_pause()) {
4179 // We have to do this before we notify the CM threads that
4180 // they can start working to make sure that all the
4181 // appropriate initialization is done on the CM object.
4182 concurrent_mark()->checkpointRootsInitialPost();
4183 collector_state()->set_mark_in_progress(true);
4184 // Note that we don't actually trigger the CM thread at
4185 // this point. We do that later when we're sure that
4186 // the current thread has completed its logging output.
4187 }
4188
4189 allocate_dummy_regions();
4190
4191 #if YOUNG_LIST_VERBOSE
4192 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4193 _young_list->print();
4194 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4195 #endif // YOUNG_LIST_VERBOSE
4196
4197 _allocator->init_mutator_alloc_region();
4198
4199 {
4200 size_t expand_bytes = g1_policy()->expansion_amount();
4201 if (expand_bytes > 0) {
4202 size_t bytes_before = capacity();
4203 // No need for an ergo verbose message here,
4204 // expansion_amount() does this when it returns a value > 0.
4205 if (!expand(expand_bytes)) {
4206 // We failed to expand the heap. Cannot do anything about it.
4207 }
4208 }
4209 }
4210
4211 // We redo the verification but now wrt to the new CSet which
4212 // has just got initialized after the previous CSet was freed.
4213 _cm->verify_no_cset_oops();
4214 _cm->note_end_of_gc();
4215
4216 // This timing is only used by the ergonomics to handle our pause target.
4217 // It is unclear why this should not include the full pause. We will
4218 // investigate this in CR 7178365.
4219 double sample_end_time_sec = os::elapsedTime();
4220 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4221 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4222 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4223
4224 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4225 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4226
4227 MemoryService::track_memory_usage();
4228
4229 // In prepare_for_verify() below we'll need to scan the deferred
4230 // update buffers to bring the RSets up-to-date if
4231 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4232 // the update buffers we'll probably need to scan cards on the
4233 // regions we just allocated to (i.e., the GC alloc
4234 // regions). However, during the last GC we called
4235 // set_saved_mark() on all the GC alloc regions, so card
4236 // scanning might skip the [saved_mark_word()...top()] area of
4237 // those regions (i.e., the area we allocated objects into
4238 // during the last GC). But it shouldn't. Given that
4239 // saved_mark_word() is conditional on whether the GC time stamp
4240 // on the region is current or not, by incrementing the GC time
4241 // stamp here we invalidate all the GC time stamps on all the
4242 // regions and saved_mark_word() will simply return top() for
4243 // all the regions. This is a nicer way of ensuring this rather
4244 // than iterating over the regions and fixing them. In fact, the
4245 // GC time stamp increment here also ensures that
4246 // saved_mark_word() will return top() between pauses, i.e.,
4247 // during concurrent refinement. So we don't need the
4248 // is_gc_active() check to decided which top to use when
4249 // scanning cards (see CR 7039627).
4250 increment_gc_time_stamp();
4251
4252 verify_after_gc();
4253 check_bitmaps("GC End");
4254
4255 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4256 ref_processor_stw()->verify_no_references_recorded();
4257
4258 // CM reference discovery will be re-enabled if necessary.
4259 }
4260
4261 // We should do this after we potentially expand the heap so
4262 // that all the COMMIT events are generated before the end GC
4263 // event, and after we retire the GC alloc regions so that all
4264 // RETIRE events are generated before the end GC event.
4265 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4266
4267 #ifdef TRACESPINNING
4268 ParallelTaskTerminator::print_termination_counts();
4269 #endif
4270
4271 gc_epilogue(false);
4272 }
4273
4274 // Print the remainder of the GC log output.
4275 log_gc_footer(os::elapsedTime() - pause_start_sec);
4276
4277 // It is not yet to safe to tell the concurrent mark to
4278 // start as we have some optional output below. We don't want the
4279 // output from the concurrent mark thread interfering with this
4280 // logging output either.
4281
4282 _hrm.verify_optional();
4283 verify_region_sets_optional();
4284
4285 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4286 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4287
4288 print_heap_after_gc();
4289 trace_heap_after_gc(_gc_tracer_stw);
4290
4291 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4292 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4293 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4294 // before any GC notifications are raised.
4295 g1mm()->update_sizes();
4296
4297 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4298 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4299 _gc_timer_stw->register_gc_end();
4300 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4301 }
4302 // It should now be safe to tell the concurrent mark thread to start
4303 // without its logging output interfering with the logging output
4304 // that came from the pause.
4305
4306 if (should_start_conc_mark) {
4307 // CAUTION: after the doConcurrentMark() call below,
4308 // the concurrent marking thread(s) could be running
4309 // concurrently with us. Make sure that anything after
4310 // this point does not assume that we are the only GC thread
4311 // running. Note: of course, the actual marking work will
4312 // not start until the safepoint itself is released in
4313 // SuspendibleThreadSet::desynchronize().
4314 doConcurrentMark();
4315 }
4316
4317 return true;
4318 }
4319
4320 void G1CollectedHeap::remove_self_forwarding_pointers() {
4321 double remove_self_forwards_start = os::elapsedTime();
4322
4323 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4324 workers()->run_task(&rsfp_task);
4325
4326 // Now restore saved marks, if any.
4327 for (uint i = 0; i < ParallelGCThreads; i++) {
4328 OopAndMarkOopStack& cur = _preserved_objs[i];
4329 while (!cur.is_empty()) {
4330 OopAndMarkOop elem = cur.pop();
4331 elem.set_mark();
4332 }
4333 cur.clear(true);
4334 }
4335
4336 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4337 }
4338
4339 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4340 if (!_evacuation_failed) {
4341 _evacuation_failed = true;
4342 }
4343
4344 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4345
4346 // We want to call the "for_promotion_failure" version only in the
4347 // case of a promotion failure.
4348 if (m->must_be_preserved_for_promotion_failure(obj)) {
4349 OopAndMarkOop elem(obj, m);
4350 _preserved_objs[worker_id].push(elem);
4351 }
4352 }
4353
4354 void G1ParCopyHelper::mark_object(oop obj) {
4355 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4356
4357 // We know that the object is not moving so it's safe to read its size.
4358 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4359 }
4360
4361 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4362 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4363 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4364 assert(from_obj != to_obj, "should not be self-forwarded");
4365
4366 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4367 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4368
4369 // The object might be in the process of being copied by another
4370 // worker so we cannot trust that its to-space image is
4371 // well-formed. So we have to read its size from its from-space
4372 // image which we know should not be changing.
4373 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4374 }
4375
4376 template <class T>
4377 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4378 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4379 _scanned_klass->record_modified_oops();
4380 }
4381 }
4382
4383 template <G1Barrier barrier, G1Mark do_mark_object>
4384 template <class T>
4385 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4386 T heap_oop = oopDesc::load_heap_oop(p);
4387
4388 if (oopDesc::is_null(heap_oop)) {
4389 return;
4390 }
4391
4392 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4393
4394 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4395
4396 const InCSetState state = _g1->in_cset_state(obj);
4397 if (state.is_in_cset()) {
4398 oop forwardee;
4399 markOop m = obj->mark();
4400 if (m->is_marked()) {
4401 forwardee = (oop) m->decode_pointer();
4402 } else {
4403 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4404 }
4405 assert(forwardee != NULL, "forwardee should not be NULL");
4406 oopDesc::encode_store_heap_oop(p, forwardee);
4407 if (do_mark_object != G1MarkNone && forwardee != obj) {
4408 // If the object is self-forwarded we don't need to explicitly
4409 // mark it, the evacuation failure protocol will do so.
4410 mark_forwarded_object(obj, forwardee);
4411 }
4412
4413 if (barrier == G1BarrierKlass) {
4414 do_klass_barrier(p, forwardee);
4415 }
4416 } else {
4417 if (state.is_humongous()) {
4418 _g1->set_humongous_is_live(obj);
4419 }
4420 // The object is not in collection set. If we're a root scanning
4421 // closure during an initial mark pause then attempt to mark the object.
4422 if (do_mark_object == G1MarkFromRoot) {
4423 mark_object(obj);
4424 }
4425 }
4426 }
4427
4428 class G1ParEvacuateFollowersClosure : public VoidClosure {
4429 private:
4430 double _start_term;
4431 double _term_time;
4432 size_t _term_attempts;
4433
4434 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4435 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4436 protected:
4437 G1CollectedHeap* _g1h;
4438 G1ParScanThreadState* _par_scan_state;
4439 RefToScanQueueSet* _queues;
4440 ParallelTaskTerminator* _terminator;
4441
4442 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4443 RefToScanQueueSet* queues() { return _queues; }
4444 ParallelTaskTerminator* terminator() { return _terminator; }
4445
4446 public:
4447 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4448 G1ParScanThreadState* par_scan_state,
4449 RefToScanQueueSet* queues,
4450 ParallelTaskTerminator* terminator)
4451 : _g1h(g1h), _par_scan_state(par_scan_state),
4452 _queues(queues), _terminator(terminator),
4453 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4454
4455 void do_void();
4456
4457 double term_time() const { return _term_time; }
4458 size_t term_attempts() const { return _term_attempts; }
4459
4460 private:
4461 inline bool offer_termination();
4462 };
4463
4464 bool G1ParEvacuateFollowersClosure::offer_termination() {
4465 G1ParScanThreadState* const pss = par_scan_state();
4466 start_term_time();
4467 const bool res = terminator()->offer_termination();
4468 end_term_time();
4469 return res;
4470 }
4471
4472 void G1ParEvacuateFollowersClosure::do_void() {
4473 G1ParScanThreadState* const pss = par_scan_state();
4474 pss->trim_queue();
4475 do {
4476 pss->steal_and_trim_queue(queues());
4477 } while (!offer_termination());
4478 }
4479
4480 class G1KlassScanClosure : public KlassClosure {
4481 G1ParCopyHelper* _closure;
4482 bool _process_only_dirty;
4483 int _count;
4484 public:
4485 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4486 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4487 void do_klass(Klass* klass) {
4488 // If the klass has not been dirtied we know that there's
4489 // no references into the young gen and we can skip it.
4490 if (!_process_only_dirty || klass->has_modified_oops()) {
4491 // Clean the klass since we're going to scavenge all the metadata.
4492 klass->clear_modified_oops();
4493
4494 // Tell the closure that this klass is the Klass to scavenge
4495 // and is the one to dirty if oops are left pointing into the young gen.
4496 _closure->set_scanned_klass(klass);
4497
4498 klass->oops_do(_closure);
4499
4500 _closure->set_scanned_klass(NULL);
4501 }
4502 _count++;
4503 }
4504 };
4505
4506 class G1ParTask : public AbstractGangTask {
4507 protected:
4508 G1CollectedHeap* _g1h;
4509 G1ParScanThreadStateSet* _pss;
4510 RefToScanQueueSet* _queues;
4511 G1RootProcessor* _root_processor;
4512 ParallelTaskTerminator _terminator;
4513 uint _n_workers;
4514
4515 public:
4516 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4517 : AbstractGangTask("G1 collection"),
4518 _g1h(g1h),
4519 _pss(per_thread_states),
4520 _queues(task_queues),
4521 _root_processor(root_processor),
4522 _terminator(n_workers, _queues),
4523 _n_workers(n_workers)
4524 {}
4525
4526 RefToScanQueueSet* queues() { return _queues; }
4527
4528 RefToScanQueue *work_queue(int i) {
4529 return queues()->queue(i);
4530 }
4531
4532 ParallelTaskTerminator* terminator() { return &_terminator; }
4533
4534 // Helps out with CLD processing.
4535 //
4536 // During InitialMark we need to:
4537 // 1) Scavenge all CLDs for the young GC.
4538 // 2) Mark all objects directly reachable from strong CLDs.
4539 template <G1Mark do_mark_object>
4540 class G1CLDClosure : public CLDClosure {
4541 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4542 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4543 G1KlassScanClosure _klass_in_cld_closure;
4544 bool _claim;
4545
4546 public:
4547 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4548 bool only_young, bool claim)
4549 : _oop_closure(oop_closure),
4550 _oop_in_klass_closure(oop_closure->g1(),
4551 oop_closure->pss()),
4552 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4553 _claim(claim) {
4554
4555 }
4556
4557 void do_cld(ClassLoaderData* cld) {
4558 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4559 }
4560 };
4561
4562 void work(uint worker_id) {
4563 if (worker_id >= _n_workers) return; // no work needed this round
4564
4565 double start_sec = os::elapsedTime();
4566 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4567
4568 {
4569 ResourceMark rm;
4570 HandleMark hm;
4571
4572 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4573
4574 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4575 pss->set_ref_processor(rp);
4576
4577 bool only_young = _g1h->collector_state()->gcs_are_young();
4578
4579 // Non-IM young GC.
4580 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss);
4581 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4582 only_young, // Only process dirty klasses.
4583 false); // No need to claim CLDs.
4584 // IM young GC.
4585 // Strong roots closures.
4586 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss);
4587 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4588 false, // Process all klasses.
4589 true); // Need to claim CLDs.
4590 // Weak roots closures.
4591 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4592 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4593 false, // Process all klasses.
4594 true); // Need to claim CLDs.
4595
4596 OopClosure* strong_root_cl;
4597 OopClosure* weak_root_cl;
4598 CLDClosure* strong_cld_cl;
4599 CLDClosure* weak_cld_cl;
4600
4601 bool trace_metadata = false;
4602
4603 if (_g1h->collector_state()->during_initial_mark_pause()) {
4604 // We also need to mark copied objects.
4605 strong_root_cl = &scan_mark_root_cl;
4606 strong_cld_cl = &scan_mark_cld_cl;
4607 if (ClassUnloadingWithConcurrentMark) {
4608 weak_root_cl = &scan_mark_weak_root_cl;
4609 weak_cld_cl = &scan_mark_weak_cld_cl;
4610 trace_metadata = true;
4611 } else {
4612 weak_root_cl = &scan_mark_root_cl;
4613 weak_cld_cl = &scan_mark_cld_cl;
4614 }
4615 } else {
4616 strong_root_cl = &scan_only_root_cl;
4617 weak_root_cl = &scan_only_root_cl;
4618 strong_cld_cl = &scan_only_cld_cl;
4619 weak_cld_cl = &scan_only_cld_cl;
4620 }
4621
4622 double start_strong_roots_sec = os::elapsedTime();
4623 _root_processor->evacuate_roots(strong_root_cl,
4624 weak_root_cl,
4625 strong_cld_cl,
4626 weak_cld_cl,
4627 trace_metadata,
4628 worker_id);
4629
4630 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4631 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4632 weak_root_cl,
4633 worker_id);
4634
4635 _pss->add_cards_scanned(worker_id, cards_scanned);
4636
4637 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4638
4639 double term_sec = 0.0;
4640 size_t evac_term_attempts = 0;
4641 {
4642 double start = os::elapsedTime();
4643 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4644 evac.do_void();
4645
4646 evac_term_attempts = evac.term_attempts();
4647 term_sec = evac.term_time();
4648 double elapsed_sec = os::elapsedTime() - start;
4649 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4650 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4651 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4652 }
4653
4654 assert(pss->queue_is_empty(), "should be empty");
4655
4656 if (PrintTerminationStats) {
4657 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4658 size_t lab_waste;
4659 size_t lab_undo_waste;
4660 pss->waste(lab_waste, lab_undo_waste);
4661 _g1h->print_termination_stats(gclog_or_tty,
4662 worker_id,
4663 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4664 strong_roots_sec * 1000.0, /* strong roots time */
4665 term_sec * 1000.0, /* evac term time */
4666 evac_term_attempts, /* evac term attempts */
4667 lab_waste, /* alloc buffer waste */
4668 lab_undo_waste /* undo waste */
4669 );
4670 }
4671
4672 // Close the inner scope so that the ResourceMark and HandleMark
4673 // destructors are executed here and are included as part of the
4674 // "GC Worker Time".
4675 }
4676 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4677 }
4678 };
4679
4680 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4681 st->print_raw_cr("GC Termination Stats");
4682 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4683 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4684 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4685 }
4686
4687 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4688 uint worker_id,
4689 double elapsed_ms,
4690 double strong_roots_ms,
4691 double term_ms,
4692 size_t term_attempts,
4693 size_t alloc_buffer_waste,
4694 size_t undo_waste) const {
4695 st->print_cr("%3d %9.2f %9.2f %6.2f "
4696 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4697 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4698 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4699 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4700 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4701 alloc_buffer_waste * HeapWordSize / K,
4702 undo_waste * HeapWordSize / K);
4703 }
4704
4705 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4706 private:
4707 BoolObjectClosure* _is_alive;
4708 int _initial_string_table_size;
4709 int _initial_symbol_table_size;
4710
4711 bool _process_strings;
4712 int _strings_processed;
4713 int _strings_removed;
4714
4715 bool _process_symbols;
4716 int _symbols_processed;
4717 int _symbols_removed;
4718
4719 public:
4720 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4721 AbstractGangTask("String/Symbol Unlinking"),
4722 _is_alive(is_alive),
4723 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4724 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4725
4726 _initial_string_table_size = StringTable::the_table()->table_size();
4727 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4728 if (process_strings) {
4729 StringTable::clear_parallel_claimed_index();
4730 }
4731 if (process_symbols) {
4732 SymbolTable::clear_parallel_claimed_index();
4733 }
4734 }
4735
4736 ~G1StringSymbolTableUnlinkTask() {
4737 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4738 err_msg("claim value %d after unlink less than initial string table size %d",
4739 StringTable::parallel_claimed_index(), _initial_string_table_size));
4740 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4741 err_msg("claim value %d after unlink less than initial symbol table size %d",
4742 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4743
4744 if (G1TraceStringSymbolTableScrubbing) {
4745 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4746 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4747 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4748 strings_processed(), strings_removed(),
4749 symbols_processed(), symbols_removed());
4750 }
4751 }
4752
4753 void work(uint worker_id) {
4754 int strings_processed = 0;
4755 int strings_removed = 0;
4756 int symbols_processed = 0;
4757 int symbols_removed = 0;
4758 if (_process_strings) {
4759 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4760 Atomic::add(strings_processed, &_strings_processed);
4761 Atomic::add(strings_removed, &_strings_removed);
4762 }
4763 if (_process_symbols) {
4764 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4765 Atomic::add(symbols_processed, &_symbols_processed);
4766 Atomic::add(symbols_removed, &_symbols_removed);
4767 }
4768 }
4769
4770 size_t strings_processed() const { return (size_t)_strings_processed; }
4771 size_t strings_removed() const { return (size_t)_strings_removed; }
4772
4773 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4774 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4775 };
4776
4777 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4778 private:
4779 static Monitor* _lock;
4780
4781 BoolObjectClosure* const _is_alive;
4782 const bool _unloading_occurred;
4783 const uint _num_workers;
4784
4785 // Variables used to claim nmethods.
4786 nmethod* _first_nmethod;
4787 volatile nmethod* _claimed_nmethod;
4788
4789 // The list of nmethods that need to be processed by the second pass.
4790 volatile nmethod* _postponed_list;
4791 volatile uint _num_entered_barrier;
4792
4793 public:
4794 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4795 _is_alive(is_alive),
4796 _unloading_occurred(unloading_occurred),
4797 _num_workers(num_workers),
4798 _first_nmethod(NULL),
4799 _claimed_nmethod(NULL),
4800 _postponed_list(NULL),
4801 _num_entered_barrier(0)
4802 {
4803 nmethod::increase_unloading_clock();
4804 // Get first alive nmethod
4805 NMethodIterator iter = NMethodIterator();
4806 if(iter.next_alive()) {
4807 _first_nmethod = iter.method();
4808 }
4809 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4810 }
4811
4812 ~G1CodeCacheUnloadingTask() {
4813 CodeCache::verify_clean_inline_caches();
4814
4815 CodeCache::set_needs_cache_clean(false);
4816 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4817
4818 CodeCache::verify_icholder_relocations();
4819 }
4820
4821 private:
4822 void add_to_postponed_list(nmethod* nm) {
4823 nmethod* old;
4824 do {
4825 old = (nmethod*)_postponed_list;
4826 nm->set_unloading_next(old);
4827 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4828 }
4829
4830 void clean_nmethod(nmethod* nm) {
4831 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4832
4833 if (postponed) {
4834 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4835 add_to_postponed_list(nm);
4836 }
4837
4838 // Mark that this thread has been cleaned/unloaded.
4839 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4840 nm->set_unloading_clock(nmethod::global_unloading_clock());
4841 }
4842
4843 void clean_nmethod_postponed(nmethod* nm) {
4844 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4845 }
4846
4847 static const int MaxClaimNmethods = 16;
4848
4849 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4850 nmethod* first;
4851 NMethodIterator last;
4852
4853 do {
4854 *num_claimed_nmethods = 0;
4855
4856 first = (nmethod*)_claimed_nmethod;
4857 last = NMethodIterator(first);
4858
4859 if (first != NULL) {
4860
4861 for (int i = 0; i < MaxClaimNmethods; i++) {
4862 if (!last.next_alive()) {
4863 break;
4864 }
4865 claimed_nmethods[i] = last.method();
4866 (*num_claimed_nmethods)++;
4867 }
4868 }
4869
4870 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4871 }
4872
4873 nmethod* claim_postponed_nmethod() {
4874 nmethod* claim;
4875 nmethod* next;
4876
4877 do {
4878 claim = (nmethod*)_postponed_list;
4879 if (claim == NULL) {
4880 return NULL;
4881 }
4882
4883 next = claim->unloading_next();
4884
4885 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4886
4887 return claim;
4888 }
4889
4890 public:
4891 // Mark that we're done with the first pass of nmethod cleaning.
4892 void barrier_mark(uint worker_id) {
4893 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4894 _num_entered_barrier++;
4895 if (_num_entered_barrier == _num_workers) {
4896 ml.notify_all();
4897 }
4898 }
4899
4900 // See if we have to wait for the other workers to
4901 // finish their first-pass nmethod cleaning work.
4902 void barrier_wait(uint worker_id) {
4903 if (_num_entered_barrier < _num_workers) {
4904 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4905 while (_num_entered_barrier < _num_workers) {
4906 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4907 }
4908 }
4909 }
4910
4911 // Cleaning and unloading of nmethods. Some work has to be postponed
4912 // to the second pass, when we know which nmethods survive.
4913 void work_first_pass(uint worker_id) {
4914 // The first nmethods is claimed by the first worker.
4915 if (worker_id == 0 && _first_nmethod != NULL) {
4916 clean_nmethod(_first_nmethod);
4917 _first_nmethod = NULL;
4918 }
4919
4920 int num_claimed_nmethods;
4921 nmethod* claimed_nmethods[MaxClaimNmethods];
4922
4923 while (true) {
4924 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4925
4926 if (num_claimed_nmethods == 0) {
4927 break;
4928 }
4929
4930 for (int i = 0; i < num_claimed_nmethods; i++) {
4931 clean_nmethod(claimed_nmethods[i]);
4932 }
4933 }
4934 }
4935
4936 void work_second_pass(uint worker_id) {
4937 nmethod* nm;
4938 // Take care of postponed nmethods.
4939 while ((nm = claim_postponed_nmethod()) != NULL) {
4940 clean_nmethod_postponed(nm);
4941 }
4942 }
4943 };
4944
4945 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4946
4947 class G1KlassCleaningTask : public StackObj {
4948 BoolObjectClosure* _is_alive;
4949 volatile jint _clean_klass_tree_claimed;
4950 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4951
4952 public:
4953 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4954 _is_alive(is_alive),
4955 _clean_klass_tree_claimed(0),
4956 _klass_iterator() {
4957 }
4958
4959 private:
4960 bool claim_clean_klass_tree_task() {
4961 if (_clean_klass_tree_claimed) {
4962 return false;
4963 }
4964
4965 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4966 }
4967
4968 InstanceKlass* claim_next_klass() {
4969 Klass* klass;
4970 do {
4971 klass =_klass_iterator.next_klass();
4972 } while (klass != NULL && !klass->oop_is_instance());
4973
4974 return (InstanceKlass*)klass;
4975 }
4976
4977 public:
4978
4979 void clean_klass(InstanceKlass* ik) {
4980 ik->clean_implementors_list(_is_alive);
4981 ik->clean_method_data(_is_alive);
4982
4983 // G1 specific cleanup work that has
4984 // been moved here to be done in parallel.
4985 ik->clean_dependent_nmethods();
4986 }
4987
4988 void work() {
4989 ResourceMark rm;
4990
4991 // One worker will clean the subklass/sibling klass tree.
4992 if (claim_clean_klass_tree_task()) {
4993 Klass::clean_subklass_tree(_is_alive);
4994 }
4995
4996 // All workers will help cleaning the classes,
4997 InstanceKlass* klass;
4998 while ((klass = claim_next_klass()) != NULL) {
4999 clean_klass(klass);
5000 }
5001 }
5002 };
5003
5004 // To minimize the remark pause times, the tasks below are done in parallel.
5005 class G1ParallelCleaningTask : public AbstractGangTask {
5006 private:
5007 G1StringSymbolTableUnlinkTask _string_symbol_task;
5008 G1CodeCacheUnloadingTask _code_cache_task;
5009 G1KlassCleaningTask _klass_cleaning_task;
5010
5011 public:
5012 // The constructor is run in the VMThread.
5013 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5014 AbstractGangTask("Parallel Cleaning"),
5015 _string_symbol_task(is_alive, process_strings, process_symbols),
5016 _code_cache_task(num_workers, is_alive, unloading_occurred),
5017 _klass_cleaning_task(is_alive) {
5018 }
5019
5020 // The parallel work done by all worker threads.
5021 void work(uint worker_id) {
5022 // Do first pass of code cache cleaning.
5023 _code_cache_task.work_first_pass(worker_id);
5024
5025 // Let the threads mark that the first pass is done.
5026 _code_cache_task.barrier_mark(worker_id);
5027
5028 // Clean the Strings and Symbols.
5029 _string_symbol_task.work(worker_id);
5030
5031 // Wait for all workers to finish the first code cache cleaning pass.
5032 _code_cache_task.barrier_wait(worker_id);
5033
5034 // Do the second code cache cleaning work, which realize on
5035 // the liveness information gathered during the first pass.
5036 _code_cache_task.work_second_pass(worker_id);
5037
5038 // Clean all klasses that were not unloaded.
5039 _klass_cleaning_task.work();
5040 }
5041 };
5042
5043
5044 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5045 bool process_strings,
5046 bool process_symbols,
5047 bool class_unloading_occurred) {
5048 uint n_workers = workers()->active_workers();
5049
5050 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5051 n_workers, class_unloading_occurred);
5052 workers()->run_task(&g1_unlink_task);
5053 }
5054
5055 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5056 bool process_strings, bool process_symbols) {
5057 {
5058 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5059 workers()->run_task(&g1_unlink_task);
5060 }
5061
5062 if (G1StringDedup::is_enabled()) {
5063 G1StringDedup::unlink(is_alive);
5064 }
5065 }
5066
5067 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5068 private:
5069 DirtyCardQueueSet* _queue;
5070 public:
5071 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5072
5073 virtual void work(uint worker_id) {
5074 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5075 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5076
5077 RedirtyLoggedCardTableEntryClosure cl;
5078 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5079
5080 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5081 }
5082 };
5083
5084 void G1CollectedHeap::redirty_logged_cards() {
5085 double redirty_logged_cards_start = os::elapsedTime();
5086
5087 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5088 dirty_card_queue_set().reset_for_par_iteration();
5089 workers()->run_task(&redirty_task);
5090
5091 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5092 dcq.merge_bufferlists(&dirty_card_queue_set());
5093 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5094
5095 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5096 }
5097
5098 // Weak Reference Processing support
5099
5100 // An always "is_alive" closure that is used to preserve referents.
5101 // If the object is non-null then it's alive. Used in the preservation
5102 // of referent objects that are pointed to by reference objects
5103 // discovered by the CM ref processor.
5104 class G1AlwaysAliveClosure: public BoolObjectClosure {
5105 G1CollectedHeap* _g1;
5106 public:
5107 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5108 bool do_object_b(oop p) {
5109 if (p != NULL) {
5110 return true;
5111 }
5112 return false;
5113 }
5114 };
5115
5116 bool G1STWIsAliveClosure::do_object_b(oop p) {
5117 // An object is reachable if it is outside the collection set,
5118 // or is inside and copied.
5119 return !_g1->is_in_cset(p) || p->is_forwarded();
5120 }
5121
5122 // Non Copying Keep Alive closure
5123 class G1KeepAliveClosure: public OopClosure {
5124 G1CollectedHeap* _g1;
5125 public:
5126 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5127 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5128 void do_oop(oop* p) {
5129 oop obj = *p;
5130 assert(obj != NULL, "the caller should have filtered out NULL values");
5131
5132 const InCSetState cset_state = _g1->in_cset_state(obj);
5133 if (!cset_state.is_in_cset_or_humongous()) {
5134 return;
5135 }
5136 if (cset_state.is_in_cset()) {
5137 assert( obj->is_forwarded(), "invariant" );
5138 *p = obj->forwardee();
5139 } else {
5140 assert(!obj->is_forwarded(), "invariant" );
5141 assert(cset_state.is_humongous(),
5142 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5143 _g1->set_humongous_is_live(obj);
5144 }
5145 }
5146 };
5147
5148 // Copying Keep Alive closure - can be called from both
5149 // serial and parallel code as long as different worker
5150 // threads utilize different G1ParScanThreadState instances
5151 // and different queues.
5152
5153 class G1CopyingKeepAliveClosure: public OopClosure {
5154 G1CollectedHeap* _g1h;
5155 OopClosure* _copy_non_heap_obj_cl;
5156 G1ParScanThreadState* _par_scan_state;
5157
5158 public:
5159 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5160 OopClosure* non_heap_obj_cl,
5161 G1ParScanThreadState* pss):
5162 _g1h(g1h),
5163 _copy_non_heap_obj_cl(non_heap_obj_cl),
5164 _par_scan_state(pss)
5165 {}
5166
5167 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5168 virtual void do_oop( oop* p) { do_oop_work(p); }
5169
5170 template <class T> void do_oop_work(T* p) {
5171 oop obj = oopDesc::load_decode_heap_oop(p);
5172
5173 if (_g1h->is_in_cset_or_humongous(obj)) {
5174 // If the referent object has been forwarded (either copied
5175 // to a new location or to itself in the event of an
5176 // evacuation failure) then we need to update the reference
5177 // field and, if both reference and referent are in the G1
5178 // heap, update the RSet for the referent.
5179 //
5180 // If the referent has not been forwarded then we have to keep
5181 // it alive by policy. Therefore we have copy the referent.
5182 //
5183 // If the reference field is in the G1 heap then we can push
5184 // on the PSS queue. When the queue is drained (after each
5185 // phase of reference processing) the object and it's followers
5186 // will be copied, the reference field set to point to the
5187 // new location, and the RSet updated. Otherwise we need to
5188 // use the the non-heap or metadata closures directly to copy
5189 // the referent object and update the pointer, while avoiding
5190 // updating the RSet.
5191
5192 if (_g1h->is_in_g1_reserved(p)) {
5193 _par_scan_state->push_on_queue(p);
5194 } else {
5195 assert(!Metaspace::contains((const void*)p),
5196 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5197 _copy_non_heap_obj_cl->do_oop(p);
5198 }
5199 }
5200 }
5201 };
5202
5203 // Serial drain queue closure. Called as the 'complete_gc'
5204 // closure for each discovered list in some of the
5205 // reference processing phases.
5206
5207 class G1STWDrainQueueClosure: public VoidClosure {
5208 protected:
5209 G1CollectedHeap* _g1h;
5210 G1ParScanThreadState* _par_scan_state;
5211
5212 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5213
5214 public:
5215 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5216 _g1h(g1h),
5217 _par_scan_state(pss)
5218 { }
5219
5220 void do_void() {
5221 G1ParScanThreadState* const pss = par_scan_state();
5222 pss->trim_queue();
5223 }
5224 };
5225
5226 // Parallel Reference Processing closures
5227
5228 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5229 // processing during G1 evacuation pauses.
5230
5231 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5232 private:
5233 G1CollectedHeap* _g1h;
5234 G1ParScanThreadStateSet* _pss;
5235 RefToScanQueueSet* _queues;
5236 WorkGang* _workers;
5237 uint _active_workers;
5238
5239 public:
5240 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5241 G1ParScanThreadStateSet* per_thread_states,
5242 WorkGang* workers,
5243 RefToScanQueueSet *task_queues,
5244 uint n_workers) :
5245 _g1h(g1h),
5246 _pss(per_thread_states),
5247 _queues(task_queues),
5248 _workers(workers),
5249 _active_workers(n_workers)
5250 {
5251 assert(n_workers > 0, "shouldn't call this otherwise");
5252 }
5253
5254 // Executes the given task using concurrent marking worker threads.
5255 virtual void execute(ProcessTask& task);
5256 virtual void execute(EnqueueTask& task);
5257 };
5258
5259 // Gang task for possibly parallel reference processing
5260
5261 class G1STWRefProcTaskProxy: public AbstractGangTask {
5262 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5263 ProcessTask& _proc_task;
5264 G1CollectedHeap* _g1h;
5265 G1ParScanThreadStateSet* _pss;
5266 RefToScanQueueSet* _task_queues;
5267 ParallelTaskTerminator* _terminator;
5268
5269 public:
5270 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5271 G1CollectedHeap* g1h,
5272 G1ParScanThreadStateSet* per_thread_states,
5273 RefToScanQueueSet *task_queues,
5274 ParallelTaskTerminator* terminator) :
5275 AbstractGangTask("Process reference objects in parallel"),
5276 _proc_task(proc_task),
5277 _g1h(g1h),
5278 _pss(per_thread_states),
5279 _task_queues(task_queues),
5280 _terminator(terminator)
5281 {}
5282
5283 virtual void work(uint worker_id) {
5284 // The reference processing task executed by a single worker.
5285 ResourceMark rm;
5286 HandleMark hm;
5287
5288 G1STWIsAliveClosure is_alive(_g1h);
5289
5290 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5291 pss->set_ref_processor(NULL);
5292
5293 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5294
5295 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5296
5297 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5298
5299 if (_g1h->collector_state()->during_initial_mark_pause()) {
5300 // We also need to mark copied objects.
5301 copy_non_heap_cl = ©_mark_non_heap_cl;
5302 }
5303
5304 // Keep alive closure.
5305 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5306
5307 // Complete GC closure
5308 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5309
5310 // Call the reference processing task's work routine.
5311 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5312
5313 // Note we cannot assert that the refs array is empty here as not all
5314 // of the processing tasks (specifically phase2 - pp2_work) execute
5315 // the complete_gc closure (which ordinarily would drain the queue) so
5316 // the queue may not be empty.
5317 }
5318 };
5319
5320 // Driver routine for parallel reference processing.
5321 // Creates an instance of the ref processing gang
5322 // task and has the worker threads execute it.
5323 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5324 assert(_workers != NULL, "Need parallel worker threads.");
5325
5326 ParallelTaskTerminator terminator(_active_workers, _queues);
5327 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5328
5329 _workers->run_task(&proc_task_proxy);
5330 }
5331
5332 // Gang task for parallel reference enqueueing.
5333
5334 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5335 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5336 EnqueueTask& _enq_task;
5337
5338 public:
5339 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5340 AbstractGangTask("Enqueue reference objects in parallel"),
5341 _enq_task(enq_task)
5342 { }
5343
5344 virtual void work(uint worker_id) {
5345 _enq_task.work(worker_id);
5346 }
5347 };
5348
5349 // Driver routine for parallel reference enqueueing.
5350 // Creates an instance of the ref enqueueing gang
5351 // task and has the worker threads execute it.
5352
5353 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5354 assert(_workers != NULL, "Need parallel worker threads.");
5355
5356 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5357
5358 _workers->run_task(&enq_task_proxy);
5359 }
5360
5361 // End of weak reference support closures
5362
5363 // Abstract task used to preserve (i.e. copy) any referent objects
5364 // that are in the collection set and are pointed to by reference
5365 // objects discovered by the CM ref processor.
5366
5367 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5368 protected:
5369 G1CollectedHeap* _g1h;
5370 G1ParScanThreadStateSet* _pss;
5371 RefToScanQueueSet* _queues;
5372 ParallelTaskTerminator _terminator;
5373 uint _n_workers;
5374
5375 public:
5376 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5377 AbstractGangTask("ParPreserveCMReferents"),
5378 _g1h(g1h),
5379 _pss(per_thread_states),
5380 _queues(task_queues),
5381 _terminator(workers, _queues),
5382 _n_workers(workers)
5383 { }
5384
5385 void work(uint worker_id) {
5386 ResourceMark rm;
5387 HandleMark hm;
5388
5389 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5390 pss->set_ref_processor(NULL);
5391 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5392
5393 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5394
5395 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5396
5397 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5398
5399 if (_g1h->collector_state()->during_initial_mark_pause()) {
5400 // We also need to mark copied objects.
5401 copy_non_heap_cl = ©_mark_non_heap_cl;
5402 }
5403
5404 // Is alive closure
5405 G1AlwaysAliveClosure always_alive(_g1h);
5406
5407 // Copying keep alive closure. Applied to referent objects that need
5408 // to be copied.
5409 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5410
5411 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5412
5413 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5414 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5415
5416 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5417 // So this must be true - but assert just in case someone decides to
5418 // change the worker ids.
5419 assert(worker_id < limit, "sanity");
5420 assert(!rp->discovery_is_atomic(), "check this code");
5421
5422 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5423 for (uint idx = worker_id; idx < limit; idx += stride) {
5424 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5425
5426 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5427 while (iter.has_next()) {
5428 // Since discovery is not atomic for the CM ref processor, we
5429 // can see some null referent objects.
5430 iter.load_ptrs(DEBUG_ONLY(true));
5431 oop ref = iter.obj();
5432
5433 // This will filter nulls.
5434 if (iter.is_referent_alive()) {
5435 iter.make_referent_alive();
5436 }
5437 iter.move_to_next();
5438 }
5439 }
5440
5441 // Drain the queue - which may cause stealing
5442 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5443 drain_queue.do_void();
5444 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5445 assert(pss->queue_is_empty(), "should be");
5446 }
5447 };
5448
5449 // Weak Reference processing during an evacuation pause (part 1).
5450 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5451 double ref_proc_start = os::elapsedTime();
5452
5453 ReferenceProcessor* rp = _ref_processor_stw;
5454 assert(rp->discovery_enabled(), "should have been enabled");
5455
5456 // Any reference objects, in the collection set, that were 'discovered'
5457 // by the CM ref processor should have already been copied (either by
5458 // applying the external root copy closure to the discovered lists, or
5459 // by following an RSet entry).
5460 //
5461 // But some of the referents, that are in the collection set, that these
5462 // reference objects point to may not have been copied: the STW ref
5463 // processor would have seen that the reference object had already
5464 // been 'discovered' and would have skipped discovering the reference,
5465 // but would not have treated the reference object as a regular oop.
5466 // As a result the copy closure would not have been applied to the
5467 // referent object.
5468 //
5469 // We need to explicitly copy these referent objects - the references
5470 // will be processed at the end of remarking.
5471 //
5472 // We also need to do this copying before we process the reference
5473 // objects discovered by the STW ref processor in case one of these
5474 // referents points to another object which is also referenced by an
5475 // object discovered by the STW ref processor.
5476
5477 uint no_of_gc_workers = workers()->active_workers();
5478
5479 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5480 per_thread_states,
5481 no_of_gc_workers,
5482 _task_queues);
5483
5484 workers()->run_task(&keep_cm_referents);
5485
5486 // Closure to test whether a referent is alive.
5487 G1STWIsAliveClosure is_alive(this);
5488
5489 // Even when parallel reference processing is enabled, the processing
5490 // of JNI refs is serial and performed serially by the current thread
5491 // rather than by a worker. The following PSS will be used for processing
5492 // JNI refs.
5493
5494 // Use only a single queue for this PSS.
5495 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5496 pss->set_ref_processor(NULL);
5497 assert(pss->queue_is_empty(), "pre-condition");
5498
5499 // We do not embed a reference processor in the copying/scanning
5500 // closures while we're actually processing the discovered
5501 // reference objects.
5502
5503 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss);
5504
5505 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5506
5507 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5508
5509 if (collector_state()->during_initial_mark_pause()) {
5510 // We also need to mark copied objects.
5511 copy_non_heap_cl = ©_mark_non_heap_cl;
5512 }
5513
5514 // Keep alive closure.
5515 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5516
5517 // Serial Complete GC closure
5518 G1STWDrainQueueClosure drain_queue(this, pss);
5519
5520 // Setup the soft refs policy...
5521 rp->setup_policy(false);
5522
5523 ReferenceProcessorStats stats;
5524 if (!rp->processing_is_mt()) {
5525 // Serial reference processing...
5526 stats = rp->process_discovered_references(&is_alive,
5527 &keep_alive,
5528 &drain_queue,
5529 NULL,
5530 _gc_timer_stw,
5531 _gc_tracer_stw->gc_id());
5532 } else {
5533 // Parallel reference processing
5534 assert(rp->num_q() == no_of_gc_workers, "sanity");
5535 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5536
5537 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5538 stats = rp->process_discovered_references(&is_alive,
5539 &keep_alive,
5540 &drain_queue,
5541 &par_task_executor,
5542 _gc_timer_stw,
5543 _gc_tracer_stw->gc_id());
5544 }
5545
5546 _gc_tracer_stw->report_gc_reference_stats(stats);
5547
5548 // We have completed copying any necessary live referent objects.
5549 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5550
5551 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5552 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5553 }
5554
5555 // Weak Reference processing during an evacuation pause (part 2).
5556 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5557 double ref_enq_start = os::elapsedTime();
5558
5559 ReferenceProcessor* rp = _ref_processor_stw;
5560 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5561
5562 // Now enqueue any remaining on the discovered lists on to
5563 // the pending list.
5564 if (!rp->processing_is_mt()) {
5565 // Serial reference processing...
5566 rp->enqueue_discovered_references();
5567 } else {
5568 // Parallel reference enqueueing
5569
5570 uint n_workers = workers()->active_workers();
5571
5572 assert(rp->num_q() == n_workers, "sanity");
5573 assert(n_workers <= rp->max_num_q(), "sanity");
5574
5575 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5576 rp->enqueue_discovered_references(&par_task_executor);
5577 }
5578
5579 rp->verify_no_references_recorded();
5580 assert(!rp->discovery_enabled(), "should have been disabled");
5581
5582 // FIXME
5583 // CM's reference processing also cleans up the string and symbol tables.
5584 // Should we do that here also? We could, but it is a serial operation
5585 // and could significantly increase the pause time.
5586
5587 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5588 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5589 }
5590
5591 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5592 _expand_heap_after_alloc_failure = true;
5593 _evacuation_failed = false;
5594
5595 // Should G1EvacuationFailureALot be in effect for this GC?
5596 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5597
5598 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5599
5600 // Disable the hot card cache.
5601 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5602 hot_card_cache->reset_hot_cache_claimed_index();
5603 hot_card_cache->set_use_cache(false);
5604
5605 const uint n_workers = workers()->active_workers();
5606
5607 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5608 double start_par_time_sec = os::elapsedTime();
5609 double end_par_time_sec;
5610
5611 {
5612 G1RootProcessor root_processor(this, n_workers);
5613 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5614 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5615 if (collector_state()->during_initial_mark_pause()) {
5616 ClassLoaderDataGraph::clear_claimed_marks();
5617 }
5618
5619 // The individual threads will set their evac-failure closures.
5620 if (PrintTerminationStats) {
5621 print_termination_stats_hdr(gclog_or_tty);
5622 }
5623
5624 workers()->run_task(&g1_par_task);
5625 end_par_time_sec = os::elapsedTime();
5626
5627 // Closing the inner scope will execute the destructor
5628 // for the G1RootProcessor object. We record the current
5629 // elapsed time before closing the scope so that time
5630 // taken for the destructor is NOT included in the
5631 // reported parallel time.
5632 }
5633
5634 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5635
5636 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5637 phase_times->record_par_time(par_time_ms);
5638
5639 double code_root_fixup_time_ms =
5640 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5641 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5642
5643 // Process any discovered reference objects - we have
5644 // to do this _before_ we retire the GC alloc regions
5645 // as we may have to copy some 'reachable' referent
5646 // objects (and their reachable sub-graphs) that were
5647 // not copied during the pause.
5648 process_discovered_references(per_thread_states);
5649
5650 if (G1StringDedup::is_enabled()) {
5651 double fixup_start = os::elapsedTime();
5652
5653 G1STWIsAliveClosure is_alive(this);
5654 G1KeepAliveClosure keep_alive(this);
5655 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5656
5657 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5658 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5659 }
5660
5661 _allocator->release_gc_alloc_regions(evacuation_info);
5662 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5663
5664 per_thread_states->flush();
5665
5666 record_obj_copy_mem_stats();
5667
5668 // Reset and re-enable the hot card cache.
5669 // Note the counts for the cards in the regions in the
5670 // collection set are reset when the collection set is freed.
5671 hot_card_cache->reset_hot_cache();
5672 hot_card_cache->set_use_cache(true);
5673
5674 purge_code_root_memory();
5675
5676 if (evacuation_failed()) {
5677 remove_self_forwarding_pointers();
5678
5679 // Reset the G1EvacuationFailureALot counters and flags
5680 // Note: the values are reset only when an actual
5681 // evacuation failure occurs.
5682 NOT_PRODUCT(reset_evacuation_should_fail();)
5683 }
5684
5685 // Enqueue any remaining references remaining on the STW
5686 // reference processor's discovered lists. We need to do
5687 // this after the card table is cleaned (and verified) as
5688 // the act of enqueueing entries on to the pending list
5689 // will log these updates (and dirty their associated
5690 // cards). We need these updates logged to update any
5691 // RSets.
5692 enqueue_discovered_references(per_thread_states);
5693
5694 redirty_logged_cards();
5695 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5696 }
5697
5698 void G1CollectedHeap::record_obj_copy_mem_stats() {
5699 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5700 create_g1_evac_summary(&_old_evac_stats));
5701 }
5702
5703 void G1CollectedHeap::free_region(HeapRegion* hr,
5704 FreeRegionList* free_list,
5705 bool par,
5706 bool locked) {
5707 assert(!hr->is_free(), "the region should not be free");
5708 assert(!hr->is_empty(), "the region should not be empty");
5709 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5710 assert(free_list != NULL, "pre-condition");
5711
5712 if (G1VerifyBitmaps) {
5713 MemRegion mr(hr->bottom(), hr->end());
5714 concurrent_mark()->clearRangePrevBitmap(mr);
5715 }
5716
5717 // Clear the card counts for this region.
5718 // Note: we only need to do this if the region is not young
5719 // (since we don't refine cards in young regions).
5720 if (!hr->is_young()) {
5721 _cg1r->hot_card_cache()->reset_card_counts(hr);
5722 }
5723 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5724 free_list->add_ordered(hr);
5725 }
5726
5727 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5728 FreeRegionList* free_list,
5729 bool par) {
5730 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5731 assert(free_list != NULL, "pre-condition");
5732
5733 size_t hr_capacity = hr->capacity();
5734 // We need to read this before we make the region non-humongous,
5735 // otherwise the information will be gone.
5736 uint last_index = hr->last_hc_index();
5737 hr->clear_humongous();
5738 free_region(hr, free_list, par);
5739
5740 uint i = hr->hrm_index() + 1;
5741 while (i < last_index) {
5742 HeapRegion* curr_hr = region_at(i);
5743 assert(curr_hr->is_continues_humongous(), "invariant");
5744 curr_hr->clear_humongous();
5745 free_region(curr_hr, free_list, par);
5746 i += 1;
5747 }
5748 }
5749
5750 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5751 const HeapRegionSetCount& humongous_regions_removed) {
5752 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5753 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5754 _old_set.bulk_remove(old_regions_removed);
5755 _humongous_set.bulk_remove(humongous_regions_removed);
5756 }
5757
5758 }
5759
5760 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5761 assert(list != NULL, "list can't be null");
5762 if (!list->is_empty()) {
5763 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5764 _hrm.insert_list_into_free_list(list);
5765 }
5766 }
5767
5768 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5769 decrease_used(bytes);
5770 }
5771
5772 class G1ParCleanupCTTask : public AbstractGangTask {
5773 G1SATBCardTableModRefBS* _ct_bs;
5774 G1CollectedHeap* _g1h;
5775 HeapRegion* volatile _su_head;
5776 public:
5777 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5778 G1CollectedHeap* g1h) :
5779 AbstractGangTask("G1 Par Cleanup CT Task"),
5780 _ct_bs(ct_bs), _g1h(g1h) { }
5781
5782 void work(uint worker_id) {
5783 HeapRegion* r;
5784 while (r = _g1h->pop_dirty_cards_region()) {
5785 clear_cards(r);
5786 }
5787 }
5788
5789 void clear_cards(HeapRegion* r) {
5790 // Cards of the survivors should have already been dirtied.
5791 if (!r->is_survivor()) {
5792 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5793 }
5794 }
5795 };
5796
5797 #ifndef PRODUCT
5798 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5799 G1CollectedHeap* _g1h;
5800 G1SATBCardTableModRefBS* _ct_bs;
5801 public:
5802 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5803 : _g1h(g1h), _ct_bs(ct_bs) { }
5804 virtual bool doHeapRegion(HeapRegion* r) {
5805 if (r->is_survivor()) {
5806 _g1h->verify_dirty_region(r);
5807 } else {
5808 _g1h->verify_not_dirty_region(r);
5809 }
5810 return false;
5811 }
5812 };
5813
5814 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5815 // All of the region should be clean.
5816 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5817 MemRegion mr(hr->bottom(), hr->end());
5818 ct_bs->verify_not_dirty_region(mr);
5819 }
5820
5821 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5822 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5823 // dirty allocated blocks as they allocate them. The thread that
5824 // retires each region and replaces it with a new one will do a
5825 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5826 // not dirty that area (one less thing to have to do while holding
5827 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5828 // is dirty.
5829 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5830 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5831 if (hr->is_young()) {
5832 ct_bs->verify_g1_young_region(mr);
5833 } else {
5834 ct_bs->verify_dirty_region(mr);
5835 }
5836 }
5837
5838 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5839 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5840 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5841 verify_dirty_region(hr);
5842 }
5843 }
5844
5845 void G1CollectedHeap::verify_dirty_young_regions() {
5846 verify_dirty_young_list(_young_list->first_region());
5847 }
5848
5849 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5850 HeapWord* tams, HeapWord* end) {
5851 guarantee(tams <= end,
5852 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5853 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5854 if (result < end) {
5855 gclog_or_tty->cr();
5856 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5857 bitmap_name, p2i(result));
5858 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5859 bitmap_name, p2i(tams), p2i(end));
5860 return false;
5861 }
5862 return true;
5863 }
5864
5865 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5866 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5867 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5868
5869 HeapWord* bottom = hr->bottom();
5870 HeapWord* ptams = hr->prev_top_at_mark_start();
5871 HeapWord* ntams = hr->next_top_at_mark_start();
5872 HeapWord* end = hr->end();
5873
5874 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5875
5876 bool res_n = true;
5877 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5878 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5879 // if we happen to be in that state.
5880 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5881 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5882 }
5883 if (!res_p || !res_n) {
5884 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5885 HR_FORMAT_PARAMS(hr));
5886 gclog_or_tty->print_cr("#### Caller: %s", caller);
5887 return false;
5888 }
5889 return true;
5890 }
5891
5892 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5893 if (!G1VerifyBitmaps) return;
5894
5895 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5896 }
5897
5898 class G1VerifyBitmapClosure : public HeapRegionClosure {
5899 private:
5900 const char* _caller;
5901 G1CollectedHeap* _g1h;
5902 bool _failures;
5903
5904 public:
5905 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5906 _caller(caller), _g1h(g1h), _failures(false) { }
5907
5908 bool failures() { return _failures; }
5909
5910 virtual bool doHeapRegion(HeapRegion* hr) {
5911 if (hr->is_continues_humongous()) return false;
5912
5913 bool result = _g1h->verify_bitmaps(_caller, hr);
5914 if (!result) {
5915 _failures = true;
5916 }
5917 return false;
5918 }
5919 };
5920
5921 void G1CollectedHeap::check_bitmaps(const char* caller) {
5922 if (!G1VerifyBitmaps) return;
5923
5924 G1VerifyBitmapClosure cl(caller, this);
5925 heap_region_iterate(&cl);
5926 guarantee(!cl.failures(), "bitmap verification");
5927 }
5928
5929 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5930 private:
5931 bool _failures;
5932 public:
5933 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5934
5935 virtual bool doHeapRegion(HeapRegion* hr) {
5936 uint i = hr->hrm_index();
5937 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5938 if (hr->is_humongous()) {
5939 if (hr->in_collection_set()) {
5940 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5941 _failures = true;
5942 return true;
5943 }
5944 if (cset_state.is_in_cset()) {
5945 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5946 _failures = true;
5947 return true;
5948 }
5949 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5950 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5951 _failures = true;
5952 return true;
5953 }
5954 } else {
5955 if (cset_state.is_humongous()) {
5956 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5957 _failures = true;
5958 return true;
5959 }
5960 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5961 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5962 hr->in_collection_set(), cset_state.value(), i);
5963 _failures = true;
5964 return true;
5965 }
5966 if (cset_state.is_in_cset()) {
5967 if (hr->is_young() != (cset_state.is_young())) {
5968 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5969 hr->is_young(), cset_state.value(), i);
5970 _failures = true;
5971 return true;
5972 }
5973 if (hr->is_old() != (cset_state.is_old())) {
5974 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5975 hr->is_old(), cset_state.value(), i);
5976 _failures = true;
5977 return true;
5978 }
5979 }
5980 }
5981 return false;
5982 }
5983
5984 bool failures() const { return _failures; }
5985 };
5986
5987 bool G1CollectedHeap::check_cset_fast_test() {
5988 G1CheckCSetFastTableClosure cl;
5989 _hrm.iterate(&cl);
5990 return !cl.failures();
5991 }
5992 #endif // PRODUCT
5993
5994 void G1CollectedHeap::cleanUpCardTable() {
5995 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5996 double start = os::elapsedTime();
5997
5998 {
5999 // Iterate over the dirty cards region list.
6000 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6001
6002 workers()->run_task(&cleanup_task);
6003 #ifndef PRODUCT
6004 if (G1VerifyCTCleanup || VerifyAfterGC) {
6005 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6006 heap_region_iterate(&cleanup_verifier);
6007 }
6008 #endif
6009 }
6010
6011 double elapsed = os::elapsedTime() - start;
6012 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6013 }
6014
6015 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
6016 size_t pre_used = 0;
6017 FreeRegionList local_free_list("Local List for CSet Freeing");
6018
6019 double young_time_ms = 0.0;
6020 double non_young_time_ms = 0.0;
6021
6022 // Since the collection set is a superset of the the young list,
6023 // all we need to do to clear the young list is clear its
6024 // head and length, and unlink any young regions in the code below
6025 _young_list->clear();
6026
6027 G1CollectorPolicy* policy = g1_policy();
6028
6029 double start_sec = os::elapsedTime();
6030 bool non_young = true;
6031
6032 HeapRegion* cur = cs_head;
6033 int age_bound = -1;
6034 size_t rs_lengths = 0;
6035
6036 while (cur != NULL) {
6037 assert(!is_on_master_free_list(cur), "sanity");
6038 if (non_young) {
6039 if (cur->is_young()) {
6040 double end_sec = os::elapsedTime();
6041 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6042 non_young_time_ms += elapsed_ms;
6043
6044 start_sec = os::elapsedTime();
6045 non_young = false;
6046 }
6047 } else {
6048 if (!cur->is_young()) {
6049 double end_sec = os::elapsedTime();
6050 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6051 young_time_ms += elapsed_ms;
6052
6053 start_sec = os::elapsedTime();
6054 non_young = true;
6055 }
6056 }
6057
6058 rs_lengths += cur->rem_set()->occupied_locked();
6059
6060 HeapRegion* next = cur->next_in_collection_set();
6061 assert(cur->in_collection_set(), "bad CS");
6062 cur->set_next_in_collection_set(NULL);
6063 clear_in_cset(cur);
6064
6065 if (cur->is_young()) {
6066 int index = cur->young_index_in_cset();
6067 assert(index != -1, "invariant");
6068 assert((uint) index < policy->young_cset_region_length(), "invariant");
6069 size_t words_survived = surviving_young_words[index];
6070 cur->record_surv_words_in_group(words_survived);
6071
6072 // At this point the we have 'popped' cur from the collection set
6073 // (linked via next_in_collection_set()) but it is still in the
6074 // young list (linked via next_young_region()). Clear the
6075 // _next_young_region field.
6076 cur->set_next_young_region(NULL);
6077 } else {
6078 int index = cur->young_index_in_cset();
6079 assert(index == -1, "invariant");
6080 }
6081
6082 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6083 (!cur->is_young() && cur->young_index_in_cset() == -1),
6084 "invariant" );
6085
6086 if (!cur->evacuation_failed()) {
6087 MemRegion used_mr = cur->used_region();
6088
6089 // And the region is empty.
6090 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6091 pre_used += cur->used();
6092 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6093 } else {
6094 cur->uninstall_surv_rate_group();
6095 if (cur->is_young()) {
6096 cur->set_young_index_in_cset(-1);
6097 }
6098 cur->set_evacuation_failed(false);
6099 // The region is now considered to be old.
6100 cur->set_old();
6101 // Do some allocation statistics accounting. Regions that failed evacuation
6102 // are always made old, so there is no need to update anything in the young
6103 // gen statistics, but we need to update old gen statistics.
6104 size_t used_words = cur->marked_bytes() / HeapWordSize;
6105 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6106 _old_set.add(cur);
6107 evacuation_info.increment_collectionset_used_after(cur->used());
6108 }
6109 cur = next;
6110 }
6111
6112 evacuation_info.set_regions_freed(local_free_list.length());
6113 policy->record_max_rs_lengths(rs_lengths);
6114 policy->cset_regions_freed();
6115
6116 double end_sec = os::elapsedTime();
6117 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6118
6119 if (non_young) {
6120 non_young_time_ms += elapsed_ms;
6121 } else {
6122 young_time_ms += elapsed_ms;
6123 }
6124
6125 prepend_to_freelist(&local_free_list);
6126 decrement_summary_bytes(pre_used);
6127 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6128 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6129 }
6130
6131 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6132 private:
6133 FreeRegionList* _free_region_list;
6134 HeapRegionSet* _proxy_set;
6135 HeapRegionSetCount _humongous_regions_removed;
6136 size_t _freed_bytes;
6137 public:
6138
6139 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6140 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6141 }
6142
6143 virtual bool doHeapRegion(HeapRegion* r) {
6144 if (!r->is_starts_humongous()) {
6145 return false;
6146 }
6147
6148 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6149
6150 oop obj = (oop)r->bottom();
6151 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6152
6153 // The following checks whether the humongous object is live are sufficient.
6154 // The main additional check (in addition to having a reference from the roots
6155 // or the young gen) is whether the humongous object has a remembered set entry.
6156 //
6157 // A humongous object cannot be live if there is no remembered set for it
6158 // because:
6159 // - there can be no references from within humongous starts regions referencing
6160 // the object because we never allocate other objects into them.
6161 // (I.e. there are no intra-region references that may be missed by the
6162 // remembered set)
6163 // - as soon there is a remembered set entry to the humongous starts region
6164 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6165 // until the end of a concurrent mark.
6166 //
6167 // It is not required to check whether the object has been found dead by marking
6168 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6169 // all objects allocated during that time are considered live.
6170 // SATB marking is even more conservative than the remembered set.
6171 // So if at this point in the collection there is no remembered set entry,
6172 // nobody has a reference to it.
6173 // At the start of collection we flush all refinement logs, and remembered sets
6174 // are completely up-to-date wrt to references to the humongous object.
6175 //
6176 // Other implementation considerations:
6177 // - never consider object arrays at this time because they would pose
6178 // considerable effort for cleaning up the the remembered sets. This is
6179 // required because stale remembered sets might reference locations that
6180 // are currently allocated into.
6181 uint region_idx = r->hrm_index();
6182 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6183 !r->rem_set()->is_empty()) {
6184
6185 if (G1TraceEagerReclaimHumongousObjects) {
6186 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",
6187 region_idx,
6188 (size_t)obj->size() * HeapWordSize,
6189 p2i(r->bottom()),
6190 r->region_num(),
6191 r->rem_set()->occupied(),
6192 r->rem_set()->strong_code_roots_list_length(),
6193 next_bitmap->isMarked(r->bottom()),
6194 g1h->is_humongous_reclaim_candidate(region_idx),
6195 obj->is_typeArray()
6196 );
6197 }
6198
6199 return false;
6200 }
6201
6202 guarantee(obj->is_typeArray(),
6203 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6204 PTR_FORMAT " is not.",
6205 p2i(r->bottom())));
6206
6207 if (G1TraceEagerReclaimHumongousObjects) {
6208 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",
6209 region_idx,
6210 (size_t)obj->size() * HeapWordSize,
6211 p2i(r->bottom()),
6212 r->region_num(),
6213 r->rem_set()->occupied(),
6214 r->rem_set()->strong_code_roots_list_length(),
6215 next_bitmap->isMarked(r->bottom()),
6216 g1h->is_humongous_reclaim_candidate(region_idx),
6217 obj->is_typeArray()
6218 );
6219 }
6220 // Need to clear mark bit of the humongous object if already set.
6221 if (next_bitmap->isMarked(r->bottom())) {
6222 next_bitmap->clear(r->bottom());
6223 }
6224 _freed_bytes += r->used();
6225 r->set_containing_set(NULL);
6226 _humongous_regions_removed.increment(1u, r->capacity());
6227 g1h->free_humongous_region(r, _free_region_list, false);
6228
6229 return false;
6230 }
6231
6232 HeapRegionSetCount& humongous_free_count() {
6233 return _humongous_regions_removed;
6234 }
6235
6236 size_t bytes_freed() const {
6237 return _freed_bytes;
6238 }
6239
6240 size_t humongous_reclaimed() const {
6241 return _humongous_regions_removed.length();
6242 }
6243 };
6244
6245 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6246 assert_at_safepoint(true);
6247
6248 if (!G1EagerReclaimHumongousObjects ||
6249 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6250 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6251 return;
6252 }
6253
6254 double start_time = os::elapsedTime();
6255
6256 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6257
6258 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6259 heap_region_iterate(&cl);
6260
6261 HeapRegionSetCount empty_set;
6262 remove_from_old_sets(empty_set, cl.humongous_free_count());
6263
6264 G1HRPrinter* hrp = hr_printer();
6265 if (hrp->is_active()) {
6266 FreeRegionListIterator iter(&local_cleanup_list);
6267 while (iter.more_available()) {
6268 HeapRegion* hr = iter.get_next();
6269 hrp->cleanup(hr);
6270 }
6271 }
6272
6273 prepend_to_freelist(&local_cleanup_list);
6274 decrement_summary_bytes(cl.bytes_freed());
6275
6276 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6277 cl.humongous_reclaimed());
6278 }
6279
6280 // This routine is similar to the above but does not record
6281 // any policy statistics or update free lists; we are abandoning
6282 // the current incremental collection set in preparation of a
6283 // full collection. After the full GC we will start to build up
6284 // the incremental collection set again.
6285 // This is only called when we're doing a full collection
6286 // and is immediately followed by the tearing down of the young list.
6287
6288 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6289 HeapRegion* cur = cs_head;
6290
6291 while (cur != NULL) {
6292 HeapRegion* next = cur->next_in_collection_set();
6293 assert(cur->in_collection_set(), "bad CS");
6294 cur->set_next_in_collection_set(NULL);
6295 clear_in_cset(cur);
6296 cur->set_young_index_in_cset(-1);
6297 cur = next;
6298 }
6299 }
6300
6301 void G1CollectedHeap::set_free_regions_coming() {
6302 if (G1ConcRegionFreeingVerbose) {
6303 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6304 "setting free regions coming");
6305 }
6306
6307 assert(!free_regions_coming(), "pre-condition");
6308 _free_regions_coming = true;
6309 }
6310
6311 void G1CollectedHeap::reset_free_regions_coming() {
6312 assert(free_regions_coming(), "pre-condition");
6313
6314 {
6315 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6316 _free_regions_coming = false;
6317 SecondaryFreeList_lock->notify_all();
6318 }
6319
6320 if (G1ConcRegionFreeingVerbose) {
6321 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6322 "reset free regions coming");
6323 }
6324 }
6325
6326 void G1CollectedHeap::wait_while_free_regions_coming() {
6327 // Most of the time we won't have to wait, so let's do a quick test
6328 // first before we take the lock.
6329 if (!free_regions_coming()) {
6330 return;
6331 }
6332
6333 if (G1ConcRegionFreeingVerbose) {
6334 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6335 "waiting for free regions");
6336 }
6337
6338 {
6339 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6340 while (free_regions_coming()) {
6341 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6342 }
6343 }
6344
6345 if (G1ConcRegionFreeingVerbose) {
6346 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6347 "done waiting for free regions");
6348 }
6349 }
6350
6351 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6352 return _allocator->is_retained_old_region(hr);
6353 }
6354
6355 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6356 _young_list->push_region(hr);
6357 }
6358
6359 class NoYoungRegionsClosure: public HeapRegionClosure {
6360 private:
6361 bool _success;
6362 public:
6363 NoYoungRegionsClosure() : _success(true) { }
6364 bool doHeapRegion(HeapRegion* r) {
6365 if (r->is_young()) {
6366 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6367 p2i(r->bottom()), p2i(r->end()));
6368 _success = false;
6369 }
6370 return false;
6371 }
6372 bool success() { return _success; }
6373 };
6374
6375 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6376 bool ret = _young_list->check_list_empty(check_sample);
6377
6378 if (check_heap) {
6379 NoYoungRegionsClosure closure;
6380 heap_region_iterate(&closure);
6381 ret = ret && closure.success();
6382 }
6383
6384 return ret;
6385 }
6386
6387 class TearDownRegionSetsClosure : public HeapRegionClosure {
6388 private:
6389 HeapRegionSet *_old_set;
6390
6391 public:
6392 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6393
6394 bool doHeapRegion(HeapRegion* r) {
6395 if (r->is_old()) {
6396 _old_set->remove(r);
6397 } else {
6398 // We ignore free regions, we'll empty the free list afterwards.
6399 // We ignore young regions, we'll empty the young list afterwards.
6400 // We ignore humongous regions, we're not tearing down the
6401 // humongous regions set.
6402 assert(r->is_free() || r->is_young() || r->is_humongous(),
6403 "it cannot be another type");
6404 }
6405 return false;
6406 }
6407
6408 ~TearDownRegionSetsClosure() {
6409 assert(_old_set->is_empty(), "post-condition");
6410 }
6411 };
6412
6413 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6414 assert_at_safepoint(true /* should_be_vm_thread */);
6415
6416 if (!free_list_only) {
6417 TearDownRegionSetsClosure cl(&_old_set);
6418 heap_region_iterate(&cl);
6419
6420 // Note that emptying the _young_list is postponed and instead done as
6421 // the first step when rebuilding the regions sets again. The reason for
6422 // this is that during a full GC string deduplication needs to know if
6423 // a collected region was young or old when the full GC was initiated.
6424 }
6425 _hrm.remove_all_free_regions();
6426 }
6427
6428 void G1CollectedHeap::increase_used(size_t bytes) {
6429 _summary_bytes_used += bytes;
6430 }
6431
6432 void G1CollectedHeap::decrease_used(size_t bytes) {
6433 assert(_summary_bytes_used >= bytes,
6434 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6435 _summary_bytes_used, bytes));
6436 _summary_bytes_used -= bytes;
6437 }
6438
6439 void G1CollectedHeap::set_used(size_t bytes) {
6440 _summary_bytes_used = bytes;
6441 }
6442
6443 class RebuildRegionSetsClosure : public HeapRegionClosure {
6444 private:
6445 bool _free_list_only;
6446 HeapRegionSet* _old_set;
6447 HeapRegionManager* _hrm;
6448 size_t _total_used;
6449
6450 public:
6451 RebuildRegionSetsClosure(bool free_list_only,
6452 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6453 _free_list_only(free_list_only),
6454 _old_set(old_set), _hrm(hrm), _total_used(0) {
6455 assert(_hrm->num_free_regions() == 0, "pre-condition");
6456 if (!free_list_only) {
6457 assert(_old_set->is_empty(), "pre-condition");
6458 }
6459 }
6460
6461 bool doHeapRegion(HeapRegion* r) {
6462 if (r->is_continues_humongous()) {
6463 return false;
6464 }
6465
6466 if (r->is_empty()) {
6467 // Add free regions to the free list
6468 r->set_free();
6469 r->set_allocation_context(AllocationContext::system());
6470 _hrm->insert_into_free_list(r);
6471 } else if (!_free_list_only) {
6472 assert(!r->is_young(), "we should not come across young regions");
6473
6474 if (r->is_humongous()) {
6475 // We ignore humongous regions. We left the humongous set unchanged.
6476 } else {
6477 // Objects that were compacted would have ended up on regions
6478 // that were previously old or free. Archive regions (which are
6479 // old) will not have been touched.
6480 assert(r->is_free() || r->is_old(), "invariant");
6481 // We now consider them old, so register as such. Leave
6482 // archive regions set that way, however, while still adding
6483 // them to the old set.
6484 if (!r->is_archive()) {
6485 r->set_old();
6486 }
6487 _old_set->add(r);
6488 }
6489 _total_used += r->used();
6490 }
6491
6492 return false;
6493 }
6494
6495 size_t total_used() {
6496 return _total_used;
6497 }
6498 };
6499
6500 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6501 assert_at_safepoint(true /* should_be_vm_thread */);
6502
6503 if (!free_list_only) {
6504 _young_list->empty_list();
6505 }
6506
6507 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6508 heap_region_iterate(&cl);
6509
6510 if (!free_list_only) {
6511 set_used(cl.total_used());
6512 if (_archive_allocator != NULL) {
6513 _archive_allocator->clear_used();
6514 }
6515 }
6516 assert(used_unlocked() == recalculate_used(),
6517 err_msg("inconsistent used_unlocked(), "
6518 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6519 used_unlocked(), recalculate_used()));
6520 }
6521
6522 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6523 _refine_cte_cl->set_concurrent(concurrent);
6524 }
6525
6526 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6527 HeapRegion* hr = heap_region_containing(p);
6528 return hr->is_in(p);
6529 }
6530
6531 // Methods for the mutator alloc region
6532
6533 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6534 bool force) {
6535 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6536 assert(!force || g1_policy()->can_expand_young_list(),
6537 "if force is true we should be able to expand the young list");
6538 bool young_list_full = g1_policy()->is_young_list_full();
6539 if (force || !young_list_full) {
6540 HeapRegion* new_alloc_region = new_region(word_size,
6541 false /* is_old */,
6542 false /* do_expand */);
6543 if (new_alloc_region != NULL) {
6544 set_region_short_lived_locked(new_alloc_region);
6545 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6546 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6547 return new_alloc_region;
6548 }
6549 }
6550 return NULL;
6551 }
6552
6553 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6554 size_t allocated_bytes) {
6555 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6556 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6557
6558 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6559 increase_used(allocated_bytes);
6560 _hr_printer.retire(alloc_region);
6561 // We update the eden sizes here, when the region is retired,
6562 // instead of when it's allocated, since this is the point that its
6563 // used space has been recored in _summary_bytes_used.
6564 g1mm()->update_eden_size();
6565 }
6566
6567 // Methods for the GC alloc regions
6568
6569 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6570 uint count,
6571 InCSetState dest) {
6572 assert(FreeList_lock->owned_by_self(), "pre-condition");
6573
6574 if (count < g1_policy()->max_regions(dest)) {
6575 const bool is_survivor = (dest.is_young());
6576 HeapRegion* new_alloc_region = new_region(word_size,
6577 !is_survivor,
6578 true /* do_expand */);
6579 if (new_alloc_region != NULL) {
6580 // We really only need to do this for old regions given that we
6581 // should never scan survivors. But it doesn't hurt to do it
6582 // for survivors too.
6583 new_alloc_region->record_timestamp();
6584 if (is_survivor) {
6585 new_alloc_region->set_survivor();
6586 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6587 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6588 } else {
6589 new_alloc_region->set_old();
6590 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6591 check_bitmaps("Old Region Allocation", new_alloc_region);
6592 }
6593 bool during_im = collector_state()->during_initial_mark_pause();
6594 new_alloc_region->note_start_of_copying(during_im);
6595 return new_alloc_region;
6596 }
6597 }
6598 return NULL;
6599 }
6600
6601 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6602 size_t allocated_bytes,
6603 InCSetState dest) {
6604 bool during_im = collector_state()->during_initial_mark_pause();
6605 alloc_region->note_end_of_copying(during_im);
6606 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6607 if (dest.is_young()) {
6608 young_list()->add_survivor_region(alloc_region);
6609 } else {
6610 _old_set.add(alloc_region);
6611 }
6612 _hr_printer.retire(alloc_region);
6613 }
6614
6615 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6616 bool expanded = false;
6617 uint index = _hrm.find_highest_free(&expanded);
6618
6619 if (index != G1_NO_HRM_INDEX) {
6620 if (expanded) {
6621 ergo_verbose1(ErgoHeapSizing,
6622 "attempt heap expansion",
6623 ergo_format_reason("requested address range outside heap bounds")
6624 ergo_format_byte("region size"),
6625 HeapRegion::GrainWords * HeapWordSize);
6626 }
6627 _hrm.allocate_free_regions_starting_at(index, 1);
6628 return region_at(index);
6629 }
6630 return NULL;
6631 }
6632
6633 // Heap region set verification
6634
6635 class VerifyRegionListsClosure : public HeapRegionClosure {
6636 private:
6637 HeapRegionSet* _old_set;
6638 HeapRegionSet* _humongous_set;
6639 HeapRegionManager* _hrm;
6640
6641 public:
6642 HeapRegionSetCount _old_count;
6643 HeapRegionSetCount _humongous_count;
6644 HeapRegionSetCount _free_count;
6645
6646 VerifyRegionListsClosure(HeapRegionSet* old_set,
6647 HeapRegionSet* humongous_set,
6648 HeapRegionManager* hrm) :
6649 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6650 _old_count(), _humongous_count(), _free_count(){ }
6651
6652 bool doHeapRegion(HeapRegion* hr) {
6653 if (hr->is_continues_humongous()) {
6654 return false;
6655 }
6656
6657 if (hr->is_young()) {
6658 // TODO
6659 } else if (hr->is_starts_humongous()) {
6660 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6661 _humongous_count.increment(1u, hr->capacity());
6662 } else if (hr->is_empty()) {
6663 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6664 _free_count.increment(1u, hr->capacity());
6665 } else if (hr->is_old()) {
6666 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6667 _old_count.increment(1u, hr->capacity());
6668 } else {
6669 // There are no other valid region types. Check for one invalid
6670 // one we can identify: pinned without old or humongous set.
6671 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6672 ShouldNotReachHere();
6673 }
6674 return false;
6675 }
6676
6677 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6678 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6679 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6680 old_set->total_capacity_bytes(), _old_count.capacity()));
6681
6682 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6683 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6684 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6685
6686 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()));
6687 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6688 free_list->total_capacity_bytes(), _free_count.capacity()));
6689 }
6690 };
6691
6692 void G1CollectedHeap::verify_region_sets() {
6693 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6694
6695 // First, check the explicit lists.
6696 _hrm.verify();
6697 {
6698 // Given that a concurrent operation might be adding regions to
6699 // the secondary free list we have to take the lock before
6700 // verifying it.
6701 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6702 _secondary_free_list.verify_list();
6703 }
6704
6705 // If a concurrent region freeing operation is in progress it will
6706 // be difficult to correctly attributed any free regions we come
6707 // across to the correct free list given that they might belong to
6708 // one of several (free_list, secondary_free_list, any local lists,
6709 // etc.). So, if that's the case we will skip the rest of the
6710 // verification operation. Alternatively, waiting for the concurrent
6711 // operation to complete will have a non-trivial effect on the GC's
6712 // operation (no concurrent operation will last longer than the
6713 // interval between two calls to verification) and it might hide
6714 // any issues that we would like to catch during testing.
6715 if (free_regions_coming()) {
6716 return;
6717 }
6718
6719 // Make sure we append the secondary_free_list on the free_list so
6720 // that all free regions we will come across can be safely
6721 // attributed to the free_list.
6722 append_secondary_free_list_if_not_empty_with_lock();
6723
6724 // Finally, make sure that the region accounting in the lists is
6725 // consistent with what we see in the heap.
6726
6727 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6728 heap_region_iterate(&cl);
6729 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6730 }
6731
6732 // Optimized nmethod scanning
6733
6734 class RegisterNMethodOopClosure: public OopClosure {
6735 G1CollectedHeap* _g1h;
6736 nmethod* _nm;
6737
6738 template <class T> void do_oop_work(T* p) {
6739 T heap_oop = oopDesc::load_heap_oop(p);
6740 if (!oopDesc::is_null(heap_oop)) {
6741 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6742 HeapRegion* hr = _g1h->heap_region_containing(obj);
6743 assert(!hr->is_continues_humongous(),
6744 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6745 " starting at " HR_FORMAT,
6746 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6747
6748 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6749 hr->add_strong_code_root_locked(_nm);
6750 }
6751 }
6752
6753 public:
6754 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6755 _g1h(g1h), _nm(nm) {}
6756
6757 void do_oop(oop* p) { do_oop_work(p); }
6758 void do_oop(narrowOop* p) { do_oop_work(p); }
6759 };
6760
6761 class UnregisterNMethodOopClosure: public OopClosure {
6762 G1CollectedHeap* _g1h;
6763 nmethod* _nm;
6764
6765 template <class T> void do_oop_work(T* p) {
6766 T heap_oop = oopDesc::load_heap_oop(p);
6767 if (!oopDesc::is_null(heap_oop)) {
6768 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6769 HeapRegion* hr = _g1h->heap_region_containing(obj);
6770 assert(!hr->is_continues_humongous(),
6771 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6772 " starting at " HR_FORMAT,
6773 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6774
6775 hr->remove_strong_code_root(_nm);
6776 }
6777 }
6778
6779 public:
6780 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6781 _g1h(g1h), _nm(nm) {}
6782
6783 void do_oop(oop* p) { do_oop_work(p); }
6784 void do_oop(narrowOop* p) { do_oop_work(p); }
6785 };
6786
6787 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6788 CollectedHeap::register_nmethod(nm);
6789
6790 guarantee(nm != NULL, "sanity");
6791 RegisterNMethodOopClosure reg_cl(this, nm);
6792 nm->oops_do(®_cl);
6793 }
6794
6795 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6796 CollectedHeap::unregister_nmethod(nm);
6797
6798 guarantee(nm != NULL, "sanity");
6799 UnregisterNMethodOopClosure reg_cl(this, nm);
6800 nm->oops_do(®_cl, true);
6801 }
6802
6803 void G1CollectedHeap::purge_code_root_memory() {
6804 double purge_start = os::elapsedTime();
6805 G1CodeRootSet::purge();
6806 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6807 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6808 }
6809
6810 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6811 G1CollectedHeap* _g1h;
6812
6813 public:
6814 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6815 _g1h(g1h) {}
6816
6817 void do_code_blob(CodeBlob* cb) {
6818 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6819 if (nm == NULL) {
6820 return;
6821 }
6822
6823 if (ScavengeRootsInCode) {
6824 _g1h->register_nmethod(nm);
6825 }
6826 }
6827 };
6828
6829 void G1CollectedHeap::rebuild_strong_code_roots() {
6830 RebuildStrongCodeRootClosure blob_cl(this);
6831 CodeCache::blobs_do(&blob_cl);
6832 }