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 _surviving_young_words(NULL),
2029 _old_marking_cycles_started(0),
2030 _old_marking_cycles_completed(0),
2031 _heap_summary_sent(false),
2032 _in_cset_fast_test(),
2033 _dirty_cards_region_list(NULL),
2034 _worker_cset_start_region(NULL),
2035 _worker_cset_start_region_time_stamp(NULL),
2036 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2037 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2038 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2039 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2040
2041 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2042 /* are_GC_task_threads */true,
2043 /* are_ConcurrentGC_threads */false);
2044 _workers->initialize_workers();
2045
2046 _allocator = G1Allocator::create_allocator(this);
2047 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2048
2049 // Override the default _filler_array_max_size so that no humongous filler
2050 // objects are created.
2051 _filler_array_max_size = _humongous_object_threshold_in_words;
2052
2053 uint n_queues = ParallelGCThreads;
2054 _task_queues = new RefToScanQueueSet(n_queues);
2055
2056 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2057 assert(n_rem_sets > 0, "Invariant.");
2058
2059 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2060 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2061 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2062
2063 for (uint i = 0; i < n_queues; i++) {
2064 RefToScanQueue* q = new RefToScanQueue();
2065 q->initialize();
2066 _task_queues->register_queue(i, q);
2067 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2068 }
2069 clear_cset_start_regions();
2070
2071 // Initialize the G1EvacuationFailureALot counters and flags.
2072 NOT_PRODUCT(reset_evacuation_should_fail();)
2073
2074 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2075 }
2076
2077 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2078 size_t size,
2079 size_t translation_factor) {
2080 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2081 // Allocate a new reserved space, preferring to use large pages.
2082 ReservedSpace rs(size, preferred_page_size);
2083 G1RegionToSpaceMapper* result =
2084 G1RegionToSpaceMapper::create_mapper(rs,
2085 size,
2086 rs.alignment(),
2087 HeapRegion::GrainBytes,
2088 translation_factor,
2089 mtGC);
2090 if (TracePageSizes) {
2091 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2092 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2093 }
2094 return result;
2095 }
2096
2097 jint G1CollectedHeap::initialize() {
2098 CollectedHeap::pre_initialize();
2099 os::enable_vtime();
2100
2101 G1Log::init();
2102
2103 // Necessary to satisfy locking discipline assertions.
2104
2105 MutexLocker x(Heap_lock);
2106
2107 // We have to initialize the printer before committing the heap, as
2108 // it will be used then.
2109 _hr_printer.set_active(G1PrintHeapRegions);
2110
2111 // While there are no constraints in the GC code that HeapWordSize
2112 // be any particular value, there are multiple other areas in the
2113 // system which believe this to be true (e.g. oop->object_size in some
2114 // cases incorrectly returns the size in wordSize units rather than
2115 // HeapWordSize).
2116 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2117
2118 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2119 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2120 size_t heap_alignment = collector_policy()->heap_alignment();
2121
2122 // Ensure that the sizes are properly aligned.
2123 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2124 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2125 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2126
2127 _refine_cte_cl = new RefineCardTableEntryClosure();
2128
2129 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2130
2131 // Reserve the maximum.
2132
2133 // When compressed oops are enabled, the preferred heap base
2134 // is calculated by subtracting the requested size from the
2135 // 32Gb boundary and using the result as the base address for
2136 // heap reservation. If the requested size is not aligned to
2137 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2138 // into the ReservedHeapSpace constructor) then the actual
2139 // base of the reserved heap may end up differing from the
2140 // address that was requested (i.e. the preferred heap base).
2141 // If this happens then we could end up using a non-optimal
2142 // compressed oops mode.
2143
2144 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2145 heap_alignment);
2146
2147 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2148
2149 // Create the barrier set for the entire reserved region.
2150 G1SATBCardTableLoggingModRefBS* bs
2151 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2152 bs->initialize();
2153 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2154 set_barrier_set(bs);
2155
2156 // Also create a G1 rem set.
2157 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2158
2159 // Carve out the G1 part of the heap.
2160
2161 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2162 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2163 G1RegionToSpaceMapper* heap_storage =
2164 G1RegionToSpaceMapper::create_mapper(g1_rs,
2165 g1_rs.size(),
2166 page_size,
2167 HeapRegion::GrainBytes,
2168 1,
2169 mtJavaHeap);
2170 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2171 max_byte_size, page_size,
2172 heap_rs.base(),
2173 heap_rs.size());
2174 heap_storage->set_mapping_changed_listener(&_listener);
2175
2176 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2177 G1RegionToSpaceMapper* bot_storage =
2178 create_aux_memory_mapper("Block offset table",
2179 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2180 G1BlockOffsetSharedArray::heap_map_factor());
2181
2182 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2183 G1RegionToSpaceMapper* cardtable_storage =
2184 create_aux_memory_mapper("Card table",
2185 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2186 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2187
2188 G1RegionToSpaceMapper* card_counts_storage =
2189 create_aux_memory_mapper("Card counts table",
2190 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2191 G1CardCounts::heap_map_factor());
2192
2193 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2194 G1RegionToSpaceMapper* prev_bitmap_storage =
2195 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2196 G1RegionToSpaceMapper* next_bitmap_storage =
2197 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2198
2199 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2200 g1_barrier_set()->initialize(cardtable_storage);
2201 // Do later initialization work for concurrent refinement.
2202 _cg1r->init(card_counts_storage);
2203
2204 // 6843694 - ensure that the maximum region index can fit
2205 // in the remembered set structures.
2206 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2207 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2208
2209 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2210 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2211 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2212 "too many cards per region");
2213
2214 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2215
2216 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2217
2218 {
2219 HeapWord* start = _hrm.reserved().start();
2220 HeapWord* end = _hrm.reserved().end();
2221 size_t granularity = HeapRegion::GrainBytes;
2222
2223 _in_cset_fast_test.initialize(start, end, granularity);
2224 _humongous_reclaim_candidates.initialize(start, end, granularity);
2225 }
2226
2227 // Create the ConcurrentMark data structure and thread.
2228 // (Must do this late, so that "max_regions" is defined.)
2229 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2230 if (_cm == NULL || !_cm->completed_initialization()) {
2231 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2232 return JNI_ENOMEM;
2233 }
2234 _cmThread = _cm->cmThread();
2235
2236 // Initialize the from_card cache structure of HeapRegionRemSet.
2237 HeapRegionRemSet::init_heap(max_regions());
2238
2239 // Now expand into the initial heap size.
2240 if (!expand(init_byte_size)) {
2241 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2242 return JNI_ENOMEM;
2243 }
2244
2245 // Perform any initialization actions delegated to the policy.
2246 g1_policy()->init();
2247
2248 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2249 SATB_Q_FL_lock,
2250 G1SATBProcessCompletedThreshold,
2251 Shared_SATB_Q_lock);
2252
2253 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2254 DirtyCardQ_CBL_mon,
2255 DirtyCardQ_FL_lock,
2256 concurrent_g1_refine()->yellow_zone(),
2257 concurrent_g1_refine()->red_zone(),
2258 Shared_DirtyCardQ_lock);
2259
2260 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2261 DirtyCardQ_CBL_mon,
2262 DirtyCardQ_FL_lock,
2263 -1, // never trigger processing
2264 -1, // no limit on length
2265 Shared_DirtyCardQ_lock,
2266 &JavaThread::dirty_card_queue_set());
2267
2268 // Initialize the card queue set used to hold cards containing
2269 // references into the collection set.
2270 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2271 DirtyCardQ_CBL_mon,
2272 DirtyCardQ_FL_lock,
2273 -1, // never trigger processing
2274 -1, // no limit on length
2275 Shared_DirtyCardQ_lock,
2276 &JavaThread::dirty_card_queue_set());
2277
2278 // Here we allocate the dummy HeapRegion that is required by the
2279 // G1AllocRegion class.
2280 HeapRegion* dummy_region = _hrm.get_dummy_region();
2281
2282 // We'll re-use the same region whether the alloc region will
2283 // require BOT updates or not and, if it doesn't, then a non-young
2284 // region will complain that it cannot support allocations without
2285 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2286 dummy_region->set_eden();
2287 // Make sure it's full.
2288 dummy_region->set_top(dummy_region->end());
2289 G1AllocRegion::setup(this, dummy_region);
2290
2291 _allocator->init_mutator_alloc_region();
2292
2293 // Do create of the monitoring and management support so that
2294 // values in the heap have been properly initialized.
2295 _g1mm = new G1MonitoringSupport(this);
2296
2297 G1StringDedup::initialize();
2298
2299 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2300 for (uint i = 0; i < ParallelGCThreads; i++) {
2301 new (&_preserved_objs[i]) OopAndMarkOopStack();
2302 }
2303
2304 return JNI_OK;
2305 }
2306
2307 void G1CollectedHeap::stop() {
2308 // Stop all concurrent threads. We do this to make sure these threads
2309 // do not continue to execute and access resources (e.g. gclog_or_tty)
2310 // that are destroyed during shutdown.
2311 _cg1r->stop();
2312 _cmThread->stop();
2313 if (G1StringDedup::is_enabled()) {
2314 G1StringDedup::stop();
2315 }
2316 }
2317
2318 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2319 return HeapRegion::max_region_size();
2320 }
2321
2322 void G1CollectedHeap::post_initialize() {
2323 CollectedHeap::post_initialize();
2324 ref_processing_init();
2325 }
2326
2327 void G1CollectedHeap::ref_processing_init() {
2328 // Reference processing in G1 currently works as follows:
2329 //
2330 // * There are two reference processor instances. One is
2331 // used to record and process discovered references
2332 // during concurrent marking; the other is used to
2333 // record and process references during STW pauses
2334 // (both full and incremental).
2335 // * Both ref processors need to 'span' the entire heap as
2336 // the regions in the collection set may be dotted around.
2337 //
2338 // * For the concurrent marking ref processor:
2339 // * Reference discovery is enabled at initial marking.
2340 // * Reference discovery is disabled and the discovered
2341 // references processed etc during remarking.
2342 // * Reference discovery is MT (see below).
2343 // * Reference discovery requires a barrier (see below).
2344 // * Reference processing may or may not be MT
2345 // (depending on the value of ParallelRefProcEnabled
2346 // and ParallelGCThreads).
2347 // * A full GC disables reference discovery by the CM
2348 // ref processor and abandons any entries on it's
2349 // discovered lists.
2350 //
2351 // * For the STW processor:
2352 // * Non MT discovery is enabled at the start of a full GC.
2353 // * Processing and enqueueing during a full GC is non-MT.
2354 // * During a full GC, references are processed after marking.
2355 //
2356 // * Discovery (may or may not be MT) is enabled at the start
2357 // of an incremental evacuation pause.
2358 // * References are processed near the end of a STW evacuation pause.
2359 // * For both types of GC:
2360 // * Discovery is atomic - i.e. not concurrent.
2361 // * Reference discovery will not need a barrier.
2362
2363 MemRegion mr = reserved_region();
2364
2365 // Concurrent Mark ref processor
2366 _ref_processor_cm =
2367 new ReferenceProcessor(mr, // span
2368 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2369 // mt processing
2370 ParallelGCThreads,
2371 // degree of mt processing
2372 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2373 // mt discovery
2374 MAX2(ParallelGCThreads, ConcGCThreads),
2375 // degree of mt discovery
2376 false,
2377 // Reference discovery is not atomic
2378 &_is_alive_closure_cm);
2379 // is alive closure
2380 // (for efficiency/performance)
2381
2382 // STW ref processor
2383 _ref_processor_stw =
2384 new ReferenceProcessor(mr, // span
2385 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2386 // mt processing
2387 ParallelGCThreads,
2388 // degree of mt processing
2389 (ParallelGCThreads > 1),
2390 // mt discovery
2391 ParallelGCThreads,
2392 // degree of mt discovery
2393 true,
2394 // Reference discovery is atomic
2395 &_is_alive_closure_stw);
2396 // is alive closure
2397 // (for efficiency/performance)
2398 }
2399
2400 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2401 return g1_policy();
2402 }
2403
2404 size_t G1CollectedHeap::capacity() const {
2405 return _hrm.length() * HeapRegion::GrainBytes;
2406 }
2407
2408 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2409 assert(!hr->is_continues_humongous(), "pre-condition");
2410 hr->reset_gc_time_stamp();
2411 if (hr->is_starts_humongous()) {
2412 uint first_index = hr->hrm_index() + 1;
2413 uint last_index = hr->last_hc_index();
2414 for (uint i = first_index; i < last_index; i += 1) {
2415 HeapRegion* chr = region_at(i);
2416 assert(chr->is_continues_humongous(), "sanity");
2417 chr->reset_gc_time_stamp();
2418 }
2419 }
2420 }
2421
2422 #ifndef PRODUCT
2423
2424 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2425 private:
2426 unsigned _gc_time_stamp;
2427 bool _failures;
2428
2429 public:
2430 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2431 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2432
2433 virtual bool doHeapRegion(HeapRegion* hr) {
2434 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2435 if (_gc_time_stamp != region_gc_time_stamp) {
2436 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2437 "expected %d", HR_FORMAT_PARAMS(hr),
2438 region_gc_time_stamp, _gc_time_stamp);
2439 _failures = true;
2440 }
2441 return false;
2442 }
2443
2444 bool failures() { return _failures; }
2445 };
2446
2447 void G1CollectedHeap::check_gc_time_stamps() {
2448 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2449 heap_region_iterate(&cl);
2450 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2451 }
2452 #endif // PRODUCT
2453
2454 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2455 DirtyCardQueue* into_cset_dcq,
2456 bool concurrent,
2457 uint worker_i) {
2458 // Clean cards in the hot card cache
2459 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2460 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2461
2462 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2463 size_t n_completed_buffers = 0;
2464 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2465 n_completed_buffers++;
2466 }
2467 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2468 dcqs.clear_n_completed_buffers();
2469 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2470 }
2471
2472 // Computes the sum of the storage used by the various regions.
2473 size_t G1CollectedHeap::used() const {
2474 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2475 if (_archive_allocator != NULL) {
2476 result += _archive_allocator->used();
2477 }
2478 return result;
2479 }
2480
2481 size_t G1CollectedHeap::used_unlocked() const {
2482 return _summary_bytes_used;
2483 }
2484
2485 class SumUsedClosure: public HeapRegionClosure {
2486 size_t _used;
2487 public:
2488 SumUsedClosure() : _used(0) {}
2489 bool doHeapRegion(HeapRegion* r) {
2490 if (!r->is_continues_humongous()) {
2491 _used += r->used();
2492 }
2493 return false;
2494 }
2495 size_t result() { return _used; }
2496 };
2497
2498 size_t G1CollectedHeap::recalculate_used() const {
2499 double recalculate_used_start = os::elapsedTime();
2500
2501 SumUsedClosure blk;
2502 heap_region_iterate(&blk);
2503
2504 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2505 return blk.result();
2506 }
2507
2508 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2509 switch (cause) {
2510 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2511 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2512 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2513 case GCCause::_g1_humongous_allocation: return true;
2514 case GCCause::_update_allocation_context_stats_inc: return true;
2515 case GCCause::_wb_conc_mark: return true;
2516 default: return false;
2517 }
2518 }
2519
2520 #ifndef PRODUCT
2521 void G1CollectedHeap::allocate_dummy_regions() {
2522 // Let's fill up most of the region
2523 size_t word_size = HeapRegion::GrainWords - 1024;
2524 // And as a result the region we'll allocate will be humongous.
2525 guarantee(is_humongous(word_size), "sanity");
2526
2527 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2528 // Let's use the existing mechanism for the allocation
2529 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2530 AllocationContext::system());
2531 if (dummy_obj != NULL) {
2532 MemRegion mr(dummy_obj, word_size);
2533 CollectedHeap::fill_with_object(mr);
2534 } else {
2535 // If we can't allocate once, we probably cannot allocate
2536 // again. Let's get out of the loop.
2537 break;
2538 }
2539 }
2540 }
2541 #endif // !PRODUCT
2542
2543 void G1CollectedHeap::increment_old_marking_cycles_started() {
2544 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2545 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2546 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2547 _old_marking_cycles_started, _old_marking_cycles_completed));
2548
2549 _old_marking_cycles_started++;
2550 }
2551
2552 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2553 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2554
2555 // We assume that if concurrent == true, then the caller is a
2556 // concurrent thread that was joined the Suspendible Thread
2557 // Set. If there's ever a cheap way to check this, we should add an
2558 // assert here.
2559
2560 // Given that this method is called at the end of a Full GC or of a
2561 // concurrent cycle, and those can be nested (i.e., a Full GC can
2562 // interrupt a concurrent cycle), the number of full collections
2563 // completed should be either one (in the case where there was no
2564 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2565 // behind the number of full collections started.
2566
2567 // This is the case for the inner caller, i.e. a Full GC.
2568 assert(concurrent ||
2569 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2570 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2571 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2572 "is inconsistent with _old_marking_cycles_completed = %u",
2573 _old_marking_cycles_started, _old_marking_cycles_completed));
2574
2575 // This is the case for the outer caller, i.e. the concurrent cycle.
2576 assert(!concurrent ||
2577 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2578 err_msg("for outer caller (concurrent cycle): "
2579 "_old_marking_cycles_started = %u "
2580 "is inconsistent with _old_marking_cycles_completed = %u",
2581 _old_marking_cycles_started, _old_marking_cycles_completed));
2582
2583 _old_marking_cycles_completed += 1;
2584
2585 // We need to clear the "in_progress" flag in the CM thread before
2586 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2587 // is set) so that if a waiter requests another System.gc() it doesn't
2588 // incorrectly see that a marking cycle is still in progress.
2589 if (concurrent) {
2590 _cmThread->set_idle();
2591 }
2592
2593 // This notify_all() will ensure that a thread that called
2594 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2595 // and it's waiting for a full GC to finish will be woken up. It is
2596 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2597 FullGCCount_lock->notify_all();
2598 }
2599
2600 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2601 collector_state()->set_concurrent_cycle_started(true);
2602 _gc_timer_cm->register_gc_start(start_time);
2603
2604 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2605 trace_heap_before_gc(_gc_tracer_cm);
2606 }
2607
2608 void G1CollectedHeap::register_concurrent_cycle_end() {
2609 if (collector_state()->concurrent_cycle_started()) {
2610 if (_cm->has_aborted()) {
2611 _gc_tracer_cm->report_concurrent_mode_failure();
2612 }
2613
2614 _gc_timer_cm->register_gc_end();
2615 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2616
2617 // Clear state variables to prepare for the next concurrent cycle.
2618 collector_state()->set_concurrent_cycle_started(false);
2619 _heap_summary_sent = false;
2620 }
2621 }
2622
2623 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2624 if (collector_state()->concurrent_cycle_started()) {
2625 // This function can be called when:
2626 // the cleanup pause is run
2627 // the concurrent cycle is aborted before the cleanup pause.
2628 // the concurrent cycle is aborted after the cleanup pause,
2629 // but before the concurrent cycle end has been registered.
2630 // Make sure that we only send the heap information once.
2631 if (!_heap_summary_sent) {
2632 trace_heap_after_gc(_gc_tracer_cm);
2633 _heap_summary_sent = true;
2634 }
2635 }
2636 }
2637
2638 void G1CollectedHeap::collect(GCCause::Cause cause) {
2639 assert_heap_not_locked();
2640
2641 uint gc_count_before;
2642 uint old_marking_count_before;
2643 uint full_gc_count_before;
2644 bool retry_gc;
2645
2646 do {
2647 retry_gc = false;
2648
2649 {
2650 MutexLocker ml(Heap_lock);
2651
2652 // Read the GC count while holding the Heap_lock
2653 gc_count_before = total_collections();
2654 full_gc_count_before = total_full_collections();
2655 old_marking_count_before = _old_marking_cycles_started;
2656 }
2657
2658 if (should_do_concurrent_full_gc(cause)) {
2659 // Schedule an initial-mark evacuation pause that will start a
2660 // concurrent cycle. We're setting word_size to 0 which means that
2661 // we are not requesting a post-GC allocation.
2662 VM_G1IncCollectionPause op(gc_count_before,
2663 0, /* word_size */
2664 true, /* should_initiate_conc_mark */
2665 g1_policy()->max_pause_time_ms(),
2666 cause);
2667 op.set_allocation_context(AllocationContext::current());
2668
2669 VMThread::execute(&op);
2670 if (!op.pause_succeeded()) {
2671 if (old_marking_count_before == _old_marking_cycles_started) {
2672 retry_gc = op.should_retry_gc();
2673 } else {
2674 // A Full GC happened while we were trying to schedule the
2675 // initial-mark GC. No point in starting a new cycle given
2676 // that the whole heap was collected anyway.
2677 }
2678
2679 if (retry_gc) {
2680 if (GC_locker::is_active_and_needs_gc()) {
2681 GC_locker::stall_until_clear();
2682 }
2683 }
2684 }
2685 } else {
2686 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2687 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2688
2689 // Schedule a standard evacuation pause. We're setting word_size
2690 // to 0 which means that we are not requesting a post-GC allocation.
2691 VM_G1IncCollectionPause op(gc_count_before,
2692 0, /* word_size */
2693 false, /* should_initiate_conc_mark */
2694 g1_policy()->max_pause_time_ms(),
2695 cause);
2696 VMThread::execute(&op);
2697 } else {
2698 // Schedule a Full GC.
2699 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2700 VMThread::execute(&op);
2701 }
2702 }
2703 } while (retry_gc);
2704 }
2705
2706 bool G1CollectedHeap::is_in(const void* p) const {
2707 if (_hrm.reserved().contains(p)) {
2708 // Given that we know that p is in the reserved space,
2709 // heap_region_containing_raw() should successfully
2710 // return the containing region.
2711 HeapRegion* hr = heap_region_containing_raw(p);
2712 return hr->is_in(p);
2713 } else {
2714 return false;
2715 }
2716 }
2717
2718 #ifdef ASSERT
2719 bool G1CollectedHeap::is_in_exact(const void* p) const {
2720 bool contains = reserved_region().contains(p);
2721 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2722 if (contains && available) {
2723 return true;
2724 } else {
2725 return false;
2726 }
2727 }
2728 #endif
2729
2730 bool G1CollectedHeap::obj_in_cs(oop obj) {
2731 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2732 return r != NULL && r->in_collection_set();
2733 }
2734
2735 // Iteration functions.
2736
2737 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2738
2739 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2740 ExtendedOopClosure* _cl;
2741 public:
2742 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2743 bool doHeapRegion(HeapRegion* r) {
2744 if (!r->is_continues_humongous()) {
2745 r->oop_iterate(_cl);
2746 }
2747 return false;
2748 }
2749 };
2750
2751 // Iterates an ObjectClosure over all objects within a HeapRegion.
2752
2753 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2754 ObjectClosure* _cl;
2755 public:
2756 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2757 bool doHeapRegion(HeapRegion* r) {
2758 if (!r->is_continues_humongous()) {
2759 r->object_iterate(_cl);
2760 }
2761 return false;
2762 }
2763 };
2764
2765 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2766 IterateObjectClosureRegionClosure blk(cl);
2767 heap_region_iterate(&blk);
2768 }
2769
2770 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2771 _hrm.iterate(cl);
2772 }
2773
2774 void
2775 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2776 uint worker_id,
2777 HeapRegionClaimer *hrclaimer,
2778 bool concurrent) const {
2779 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2780 }
2781
2782 // Clear the cached CSet starting regions and (more importantly)
2783 // the time stamps. Called when we reset the GC time stamp.
2784 void G1CollectedHeap::clear_cset_start_regions() {
2785 assert(_worker_cset_start_region != NULL, "sanity");
2786 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2787
2788 for (uint i = 0; i < ParallelGCThreads; i++) {
2789 _worker_cset_start_region[i] = NULL;
2790 _worker_cset_start_region_time_stamp[i] = 0;
2791 }
2792 }
2793
2794 // Given the id of a worker, obtain or calculate a suitable
2795 // starting region for iterating over the current collection set.
2796 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2797 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2798
2799 HeapRegion* result = NULL;
2800 unsigned gc_time_stamp = get_gc_time_stamp();
2801
2802 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2803 // Cached starting region for current worker was set
2804 // during the current pause - so it's valid.
2805 // Note: the cached starting heap region may be NULL
2806 // (when the collection set is empty).
2807 result = _worker_cset_start_region[worker_i];
2808 assert(result == NULL || result->in_collection_set(), "sanity");
2809 return result;
2810 }
2811
2812 // The cached entry was not valid so let's calculate
2813 // a suitable starting heap region for this worker.
2814
2815 // We want the parallel threads to start their collection
2816 // set iteration at different collection set regions to
2817 // avoid contention.
2818 // If we have:
2819 // n collection set regions
2820 // p threads
2821 // Then thread t will start at region floor ((t * n) / p)
2822
2823 result = g1_policy()->collection_set();
2824 uint cs_size = g1_policy()->cset_region_length();
2825 uint active_workers = workers()->active_workers();
2826
2827 uint end_ind = (cs_size * worker_i) / active_workers;
2828 uint start_ind = 0;
2829
2830 if (worker_i > 0 &&
2831 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2832 // Previous workers starting region is valid
2833 // so let's iterate from there
2834 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2835 result = _worker_cset_start_region[worker_i - 1];
2836 }
2837
2838 for (uint i = start_ind; i < end_ind; i++) {
2839 result = result->next_in_collection_set();
2840 }
2841
2842 // Note: the calculated starting heap region may be NULL
2843 // (when the collection set is empty).
2844 assert(result == NULL || result->in_collection_set(), "sanity");
2845 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2846 "should be updated only once per pause");
2847 _worker_cset_start_region[worker_i] = result;
2848 OrderAccess::storestore();
2849 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2850 return result;
2851 }
2852
2853 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2854 HeapRegion* r = g1_policy()->collection_set();
2855 while (r != NULL) {
2856 HeapRegion* next = r->next_in_collection_set();
2857 if (cl->doHeapRegion(r)) {
2858 cl->incomplete();
2859 return;
2860 }
2861 r = next;
2862 }
2863 }
2864
2865 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2866 HeapRegionClosure *cl) {
2867 if (r == NULL) {
2868 // The CSet is empty so there's nothing to do.
2869 return;
2870 }
2871
2872 assert(r->in_collection_set(),
2873 "Start region must be a member of the collection set.");
2874 HeapRegion* cur = r;
2875 while (cur != NULL) {
2876 HeapRegion* next = cur->next_in_collection_set();
2877 if (cl->doHeapRegion(cur) && false) {
2878 cl->incomplete();
2879 return;
2880 }
2881 cur = next;
2882 }
2883 cur = g1_policy()->collection_set();
2884 while (cur != r) {
2885 HeapRegion* next = cur->next_in_collection_set();
2886 if (cl->doHeapRegion(cur) && false) {
2887 cl->incomplete();
2888 return;
2889 }
2890 cur = next;
2891 }
2892 }
2893
2894 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2895 HeapRegion* result = _hrm.next_region_in_heap(from);
2896 while (result != NULL && result->is_pinned()) {
2897 result = _hrm.next_region_in_heap(result);
2898 }
2899 return result;
2900 }
2901
2902 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2903 HeapRegion* hr = heap_region_containing(addr);
2904 return hr->block_start(addr);
2905 }
2906
2907 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2908 HeapRegion* hr = heap_region_containing(addr);
2909 return hr->block_size(addr);
2910 }
2911
2912 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2913 HeapRegion* hr = heap_region_containing(addr);
2914 return hr->block_is_obj(addr);
2915 }
2916
2917 bool G1CollectedHeap::supports_tlab_allocation() const {
2918 return true;
2919 }
2920
2921 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2922 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2923 }
2924
2925 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2926 return young_list()->eden_used_bytes();
2927 }
2928
2929 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2930 // must be equal to the humongous object limit.
2931 size_t G1CollectedHeap::max_tlab_size() const {
2932 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2933 }
2934
2935 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2936 AllocationContext_t context = AllocationContext::current();
2937 return _allocator->unsafe_max_tlab_alloc(context);
2938 }
2939
2940 size_t G1CollectedHeap::max_capacity() const {
2941 return _hrm.reserved().byte_size();
2942 }
2943
2944 jlong G1CollectedHeap::millis_since_last_gc() {
2945 // assert(false, "NYI");
2946 return 0;
2947 }
2948
2949 void G1CollectedHeap::prepare_for_verify() {
2950 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2951 ensure_parsability(false);
2952 }
2953 g1_rem_set()->prepare_for_verify();
2954 }
2955
2956 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2957 VerifyOption vo) {
2958 switch (vo) {
2959 case VerifyOption_G1UsePrevMarking:
2960 return hr->obj_allocated_since_prev_marking(obj);
2961 case VerifyOption_G1UseNextMarking:
2962 return hr->obj_allocated_since_next_marking(obj);
2963 case VerifyOption_G1UseMarkWord:
2964 return false;
2965 default:
2966 ShouldNotReachHere();
2967 }
2968 return false; // keep some compilers happy
2969 }
2970
2971 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2972 switch (vo) {
2973 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2974 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2975 case VerifyOption_G1UseMarkWord: return NULL;
2976 default: ShouldNotReachHere();
2977 }
2978 return NULL; // keep some compilers happy
2979 }
2980
2981 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2982 switch (vo) {
2983 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2984 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2985 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2986 default: ShouldNotReachHere();
2987 }
2988 return false; // keep some compilers happy
2989 }
2990
2991 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2992 switch (vo) {
2993 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2994 case VerifyOption_G1UseNextMarking: return "NTAMS";
2995 case VerifyOption_G1UseMarkWord: return "NONE";
2996 default: ShouldNotReachHere();
2997 }
2998 return NULL; // keep some compilers happy
2999 }
3000
3001 class VerifyRootsClosure: public OopClosure {
3002 private:
3003 G1CollectedHeap* _g1h;
3004 VerifyOption _vo;
3005 bool _failures;
3006 public:
3007 // _vo == UsePrevMarking -> use "prev" marking information,
3008 // _vo == UseNextMarking -> use "next" marking information,
3009 // _vo == UseMarkWord -> use mark word from object header.
3010 VerifyRootsClosure(VerifyOption vo) :
3011 _g1h(G1CollectedHeap::heap()),
3012 _vo(vo),
3013 _failures(false) { }
3014
3015 bool failures() { return _failures; }
3016
3017 template <class T> void do_oop_nv(T* p) {
3018 T heap_oop = oopDesc::load_heap_oop(p);
3019 if (!oopDesc::is_null(heap_oop)) {
3020 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3021 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3022 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3023 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3024 if (_vo == VerifyOption_G1UseMarkWord) {
3025 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3026 }
3027 obj->print_on(gclog_or_tty);
3028 _failures = true;
3029 }
3030 }
3031 }
3032
3033 void do_oop(oop* p) { do_oop_nv(p); }
3034 void do_oop(narrowOop* p) { do_oop_nv(p); }
3035 };
3036
3037 class G1VerifyCodeRootOopClosure: public OopClosure {
3038 G1CollectedHeap* _g1h;
3039 OopClosure* _root_cl;
3040 nmethod* _nm;
3041 VerifyOption _vo;
3042 bool _failures;
3043
3044 template <class T> void do_oop_work(T* p) {
3045 // First verify that this root is live
3046 _root_cl->do_oop(p);
3047
3048 if (!G1VerifyHeapRegionCodeRoots) {
3049 // We're not verifying the code roots attached to heap region.
3050 return;
3051 }
3052
3053 // Don't check the code roots during marking verification in a full GC
3054 if (_vo == VerifyOption_G1UseMarkWord) {
3055 return;
3056 }
3057
3058 // Now verify that the current nmethod (which contains p) is
3059 // in the code root list of the heap region containing the
3060 // object referenced by p.
3061
3062 T heap_oop = oopDesc::load_heap_oop(p);
3063 if (!oopDesc::is_null(heap_oop)) {
3064 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3065
3066 // Now fetch the region containing the object
3067 HeapRegion* hr = _g1h->heap_region_containing(obj);
3068 HeapRegionRemSet* hrrs = hr->rem_set();
3069 // Verify that the strong code root list for this region
3070 // contains the nmethod
3071 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3072 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3073 "from nmethod " PTR_FORMAT " not in strong "
3074 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3075 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3076 _failures = true;
3077 }
3078 }
3079 }
3080
3081 public:
3082 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3083 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3084
3085 void do_oop(oop* p) { do_oop_work(p); }
3086 void do_oop(narrowOop* p) { do_oop_work(p); }
3087
3088 void set_nmethod(nmethod* nm) { _nm = nm; }
3089 bool failures() { return _failures; }
3090 };
3091
3092 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3093 G1VerifyCodeRootOopClosure* _oop_cl;
3094
3095 public:
3096 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3097 _oop_cl(oop_cl) {}
3098
3099 void do_code_blob(CodeBlob* cb) {
3100 nmethod* nm = cb->as_nmethod_or_null();
3101 if (nm != NULL) {
3102 _oop_cl->set_nmethod(nm);
3103 nm->oops_do(_oop_cl);
3104 }
3105 }
3106 };
3107
3108 class YoungRefCounterClosure : public OopClosure {
3109 G1CollectedHeap* _g1h;
3110 int _count;
3111 public:
3112 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3113 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3114 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3115
3116 int count() { return _count; }
3117 void reset_count() { _count = 0; };
3118 };
3119
3120 class VerifyKlassClosure: public KlassClosure {
3121 YoungRefCounterClosure _young_ref_counter_closure;
3122 OopClosure *_oop_closure;
3123 public:
3124 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3125 void do_klass(Klass* k) {
3126 k->oops_do(_oop_closure);
3127
3128 _young_ref_counter_closure.reset_count();
3129 k->oops_do(&_young_ref_counter_closure);
3130 if (_young_ref_counter_closure.count() > 0) {
3131 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3132 }
3133 }
3134 };
3135
3136 class VerifyLivenessOopClosure: public OopClosure {
3137 G1CollectedHeap* _g1h;
3138 VerifyOption _vo;
3139 public:
3140 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3141 _g1h(g1h), _vo(vo)
3142 { }
3143 void do_oop(narrowOop *p) { do_oop_work(p); }
3144 void do_oop( oop *p) { do_oop_work(p); }
3145
3146 template <class T> void do_oop_work(T *p) {
3147 oop obj = oopDesc::load_decode_heap_oop(p);
3148 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3149 "Dead object referenced by a not dead object");
3150 }
3151 };
3152
3153 class VerifyObjsInRegionClosure: public ObjectClosure {
3154 private:
3155 G1CollectedHeap* _g1h;
3156 size_t _live_bytes;
3157 HeapRegion *_hr;
3158 VerifyOption _vo;
3159 public:
3160 // _vo == UsePrevMarking -> use "prev" marking information,
3161 // _vo == UseNextMarking -> use "next" marking information,
3162 // _vo == UseMarkWord -> use mark word from object header.
3163 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3164 : _live_bytes(0), _hr(hr), _vo(vo) {
3165 _g1h = G1CollectedHeap::heap();
3166 }
3167 void do_object(oop o) {
3168 VerifyLivenessOopClosure isLive(_g1h, _vo);
3169 assert(o != NULL, "Huh?");
3170 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3171 // If the object is alive according to the mark word,
3172 // then verify that the marking information agrees.
3173 // Note we can't verify the contra-positive of the
3174 // above: if the object is dead (according to the mark
3175 // word), it may not be marked, or may have been marked
3176 // but has since became dead, or may have been allocated
3177 // since the last marking.
3178 if (_vo == VerifyOption_G1UseMarkWord) {
3179 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3180 }
3181
3182 o->oop_iterate_no_header(&isLive);
3183 if (!_hr->obj_allocated_since_prev_marking(o)) {
3184 size_t obj_size = o->size(); // Make sure we don't overflow
3185 _live_bytes += (obj_size * HeapWordSize);
3186 }
3187 }
3188 }
3189 size_t live_bytes() { return _live_bytes; }
3190 };
3191
3192 class VerifyArchiveOopClosure: public OopClosure {
3193 public:
3194 VerifyArchiveOopClosure(HeapRegion *hr) { }
3195 void do_oop(narrowOop *p) { do_oop_work(p); }
3196 void do_oop( oop *p) { do_oop_work(p); }
3197
3198 template <class T> void do_oop_work(T *p) {
3199 oop obj = oopDesc::load_decode_heap_oop(p);
3200 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3201 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3202 p2i(p), p2i(obj)));
3203 }
3204 };
3205
3206 class VerifyArchiveRegionClosure: public ObjectClosure {
3207 public:
3208 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3209 // Verify that all object pointers are to archive regions.
3210 void do_object(oop o) {
3211 VerifyArchiveOopClosure checkOop(NULL);
3212 assert(o != NULL, "Should not be here for NULL oops");
3213 o->oop_iterate_no_header(&checkOop);
3214 }
3215 };
3216
3217 class VerifyRegionClosure: public HeapRegionClosure {
3218 private:
3219 bool _par;
3220 VerifyOption _vo;
3221 bool _failures;
3222 public:
3223 // _vo == UsePrevMarking -> use "prev" marking information,
3224 // _vo == UseNextMarking -> use "next" marking information,
3225 // _vo == UseMarkWord -> use mark word from object header.
3226 VerifyRegionClosure(bool par, VerifyOption vo)
3227 : _par(par),
3228 _vo(vo),
3229 _failures(false) {}
3230
3231 bool failures() {
3232 return _failures;
3233 }
3234
3235 bool doHeapRegion(HeapRegion* r) {
3236 // For archive regions, verify there are no heap pointers to
3237 // non-pinned regions. For all others, verify liveness info.
3238 if (r->is_archive()) {
3239 VerifyArchiveRegionClosure verify_oop_pointers(r);
3240 r->object_iterate(&verify_oop_pointers);
3241 return true;
3242 }
3243 if (!r->is_continues_humongous()) {
3244 bool failures = false;
3245 r->verify(_vo, &failures);
3246 if (failures) {
3247 _failures = true;
3248 } else {
3249 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3250 r->object_iterate(¬_dead_yet_cl);
3251 if (_vo != VerifyOption_G1UseNextMarking) {
3252 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3253 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3254 "max_live_bytes " SIZE_FORMAT " "
3255 "< calculated " SIZE_FORMAT,
3256 p2i(r->bottom()), p2i(r->end()),
3257 r->max_live_bytes(),
3258 not_dead_yet_cl.live_bytes());
3259 _failures = true;
3260 }
3261 } else {
3262 // When vo == UseNextMarking we cannot currently do a sanity
3263 // check on the live bytes as the calculation has not been
3264 // finalized yet.
3265 }
3266 }
3267 }
3268 return false; // stop the region iteration if we hit a failure
3269 }
3270 };
3271
3272 // This is the task used for parallel verification of the heap regions
3273
3274 class G1ParVerifyTask: public AbstractGangTask {
3275 private:
3276 G1CollectedHeap* _g1h;
3277 VerifyOption _vo;
3278 bool _failures;
3279 HeapRegionClaimer _hrclaimer;
3280
3281 public:
3282 // _vo == UsePrevMarking -> use "prev" marking information,
3283 // _vo == UseNextMarking -> use "next" marking information,
3284 // _vo == UseMarkWord -> use mark word from object header.
3285 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3286 AbstractGangTask("Parallel verify task"),
3287 _g1h(g1h),
3288 _vo(vo),
3289 _failures(false),
3290 _hrclaimer(g1h->workers()->active_workers()) {}
3291
3292 bool failures() {
3293 return _failures;
3294 }
3295
3296 void work(uint worker_id) {
3297 HandleMark hm;
3298 VerifyRegionClosure blk(true, _vo);
3299 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3300 if (blk.failures()) {
3301 _failures = true;
3302 }
3303 }
3304 };
3305
3306 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3307 if (SafepointSynchronize::is_at_safepoint()) {
3308 assert(Thread::current()->is_VM_thread(),
3309 "Expected to be executed serially by the VM thread at this point");
3310
3311 if (!silent) { gclog_or_tty->print("Roots "); }
3312 VerifyRootsClosure rootsCl(vo);
3313 VerifyKlassClosure klassCl(this, &rootsCl);
3314 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3315
3316 // We apply the relevant closures to all the oops in the
3317 // system dictionary, class loader data graph, the string table
3318 // and the nmethods in the code cache.
3319 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3320 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3321
3322 {
3323 G1RootProcessor root_processor(this, 1);
3324 root_processor.process_all_roots(&rootsCl,
3325 &cldCl,
3326 &blobsCl);
3327 }
3328
3329 bool failures = rootsCl.failures() || codeRootsCl.failures();
3330
3331 if (vo != VerifyOption_G1UseMarkWord) {
3332 // If we're verifying during a full GC then the region sets
3333 // will have been torn down at the start of the GC. Therefore
3334 // verifying the region sets will fail. So we only verify
3335 // the region sets when not in a full GC.
3336 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3337 verify_region_sets();
3338 }
3339
3340 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3341 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3342
3343 G1ParVerifyTask task(this, vo);
3344 workers()->run_task(&task);
3345 if (task.failures()) {
3346 failures = true;
3347 }
3348
3349 } else {
3350 VerifyRegionClosure blk(false, vo);
3351 heap_region_iterate(&blk);
3352 if (blk.failures()) {
3353 failures = true;
3354 }
3355 }
3356
3357 if (G1StringDedup::is_enabled()) {
3358 if (!silent) gclog_or_tty->print("StrDedup ");
3359 G1StringDedup::verify();
3360 }
3361
3362 if (failures) {
3363 gclog_or_tty->print_cr("Heap:");
3364 // It helps to have the per-region information in the output to
3365 // help us track down what went wrong. This is why we call
3366 // print_extended_on() instead of print_on().
3367 print_extended_on(gclog_or_tty);
3368 gclog_or_tty->cr();
3369 gclog_or_tty->flush();
3370 }
3371 guarantee(!failures, "there should not have been any failures");
3372 } else {
3373 if (!silent) {
3374 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3375 if (G1StringDedup::is_enabled()) {
3376 gclog_or_tty->print(", StrDedup");
3377 }
3378 gclog_or_tty->print(") ");
3379 }
3380 }
3381 }
3382
3383 void G1CollectedHeap::verify(bool silent) {
3384 verify(silent, VerifyOption_G1UsePrevMarking);
3385 }
3386
3387 double G1CollectedHeap::verify(bool guard, const char* msg) {
3388 double verify_time_ms = 0.0;
3389
3390 if (guard && total_collections() >= VerifyGCStartAt) {
3391 double verify_start = os::elapsedTime();
3392 HandleMark hm; // Discard invalid handles created during verification
3393 prepare_for_verify();
3394 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3395 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3396 }
3397
3398 return verify_time_ms;
3399 }
3400
3401 void G1CollectedHeap::verify_before_gc() {
3402 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3403 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3404 }
3405
3406 void G1CollectedHeap::verify_after_gc() {
3407 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3408 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3409 }
3410
3411 class PrintRegionClosure: public HeapRegionClosure {
3412 outputStream* _st;
3413 public:
3414 PrintRegionClosure(outputStream* st) : _st(st) {}
3415 bool doHeapRegion(HeapRegion* r) {
3416 r->print_on(_st);
3417 return false;
3418 }
3419 };
3420
3421 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3422 const HeapRegion* hr,
3423 const VerifyOption vo) const {
3424 switch (vo) {
3425 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3426 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3427 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3428 default: ShouldNotReachHere();
3429 }
3430 return false; // keep some compilers happy
3431 }
3432
3433 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3434 const VerifyOption vo) const {
3435 switch (vo) {
3436 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3437 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3438 case VerifyOption_G1UseMarkWord: {
3439 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3440 return !obj->is_gc_marked() && !hr->is_archive();
3441 }
3442 default: ShouldNotReachHere();
3443 }
3444 return false; // keep some compilers happy
3445 }
3446
3447 void G1CollectedHeap::print_on(outputStream* st) const {
3448 st->print(" %-20s", "garbage-first heap");
3449 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3450 capacity()/K, used_unlocked()/K);
3451 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3452 p2i(_hrm.reserved().start()),
3453 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3454 p2i(_hrm.reserved().end()));
3455 st->cr();
3456 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3457 uint young_regions = _young_list->length();
3458 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3459 (size_t) young_regions * HeapRegion::GrainBytes / K);
3460 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3461 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3462 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3463 st->cr();
3464 MetaspaceAux::print_on(st);
3465 }
3466
3467 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3468 print_on(st);
3469
3470 // Print the per-region information.
3471 st->cr();
3472 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3473 "HS=humongous(starts), HC=humongous(continues), "
3474 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3475 "PTAMS=previous top-at-mark-start, "
3476 "NTAMS=next top-at-mark-start)");
3477 PrintRegionClosure blk(st);
3478 heap_region_iterate(&blk);
3479 }
3480
3481 void G1CollectedHeap::print_on_error(outputStream* st) const {
3482 this->CollectedHeap::print_on_error(st);
3483
3484 if (_cm != NULL) {
3485 st->cr();
3486 _cm->print_on_error(st);
3487 }
3488 }
3489
3490 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3491 workers()->print_worker_threads_on(st);
3492 _cmThread->print_on(st);
3493 st->cr();
3494 _cm->print_worker_threads_on(st);
3495 _cg1r->print_worker_threads_on(st);
3496 if (G1StringDedup::is_enabled()) {
3497 G1StringDedup::print_worker_threads_on(st);
3498 }
3499 }
3500
3501 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3502 workers()->threads_do(tc);
3503 tc->do_thread(_cmThread);
3504 _cg1r->threads_do(tc);
3505 if (G1StringDedup::is_enabled()) {
3506 G1StringDedup::threads_do(tc);
3507 }
3508 }
3509
3510 void G1CollectedHeap::print_tracing_info() const {
3511 // We'll overload this to mean "trace GC pause statistics."
3512 if (TraceYoungGenTime || TraceOldGenTime) {
3513 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3514 // to that.
3515 g1_policy()->print_tracing_info();
3516 }
3517 if (G1SummarizeRSetStats) {
3518 g1_rem_set()->print_summary_info();
3519 }
3520 if (G1SummarizeConcMark) {
3521 concurrent_mark()->print_summary_info();
3522 }
3523 g1_policy()->print_yg_surv_rate_info();
3524 }
3525
3526 #ifndef PRODUCT
3527 // Helpful for debugging RSet issues.
3528
3529 class PrintRSetsClosure : public HeapRegionClosure {
3530 private:
3531 const char* _msg;
3532 size_t _occupied_sum;
3533
3534 public:
3535 bool doHeapRegion(HeapRegion* r) {
3536 HeapRegionRemSet* hrrs = r->rem_set();
3537 size_t occupied = hrrs->occupied();
3538 _occupied_sum += occupied;
3539
3540 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3541 HR_FORMAT_PARAMS(r));
3542 if (occupied == 0) {
3543 gclog_or_tty->print_cr(" RSet is empty");
3544 } else {
3545 hrrs->print();
3546 }
3547 gclog_or_tty->print_cr("----------");
3548 return false;
3549 }
3550
3551 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3552 gclog_or_tty->cr();
3553 gclog_or_tty->print_cr("========================================");
3554 gclog_or_tty->print_cr("%s", msg);
3555 gclog_or_tty->cr();
3556 }
3557
3558 ~PrintRSetsClosure() {
3559 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3560 gclog_or_tty->print_cr("========================================");
3561 gclog_or_tty->cr();
3562 }
3563 };
3564
3565 void G1CollectedHeap::print_cset_rsets() {
3566 PrintRSetsClosure cl("Printing CSet RSets");
3567 collection_set_iterate(&cl);
3568 }
3569
3570 void G1CollectedHeap::print_all_rsets() {
3571 PrintRSetsClosure cl("Printing All RSets");;
3572 heap_region_iterate(&cl);
3573 }
3574 #endif // PRODUCT
3575
3576 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3577 YoungList* young_list = heap()->young_list();
3578
3579 size_t eden_used_bytes = young_list->eden_used_bytes();
3580 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3581
3582 size_t eden_capacity_bytes =
3583 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3584
3585 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3586 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3587 }
3588
3589 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3590 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3591 stats->unused(), stats->used(), stats->region_end_waste(),
3592 stats->regions_filled(), stats->direct_allocated(),
3593 stats->failure_used(), stats->failure_waste());
3594 }
3595
3596 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3597 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3598 gc_tracer->report_gc_heap_summary(when, heap_summary);
3599
3600 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3601 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3602 }
3603
3604
3605 G1CollectedHeap* G1CollectedHeap::heap() {
3606 CollectedHeap* heap = Universe::heap();
3607 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3608 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3609 return (G1CollectedHeap*)heap;
3610 }
3611
3612 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3613 // always_do_update_barrier = false;
3614 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3615 // Fill TLAB's and such
3616 accumulate_statistics_all_tlabs();
3617 ensure_parsability(true);
3618
3619 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3620 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3621 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3622 }
3623 }
3624
3625 void G1CollectedHeap::gc_epilogue(bool full) {
3626
3627 if (G1SummarizeRSetStats &&
3628 (G1SummarizeRSetStatsPeriod > 0) &&
3629 // we are at the end of the GC. Total collections has already been increased.
3630 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3631 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3632 }
3633
3634 // FIXME: what is this about?
3635 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3636 // is set.
3637 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3638 "derived pointer present"));
3639 // always_do_update_barrier = true;
3640
3641 resize_all_tlabs();
3642 allocation_context_stats().update(full);
3643
3644 // We have just completed a GC. Update the soft reference
3645 // policy with the new heap occupancy
3646 Universe::update_heap_info_at_gc();
3647 }
3648
3649 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3650 uint gc_count_before,
3651 bool* succeeded,
3652 GCCause::Cause gc_cause) {
3653 assert_heap_not_locked_and_not_at_safepoint();
3654 g1_policy()->record_stop_world_start();
3655 VM_G1IncCollectionPause op(gc_count_before,
3656 word_size,
3657 false, /* should_initiate_conc_mark */
3658 g1_policy()->max_pause_time_ms(),
3659 gc_cause);
3660
3661 op.set_allocation_context(AllocationContext::current());
3662 VMThread::execute(&op);
3663
3664 HeapWord* result = op.result();
3665 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3666 assert(result == NULL || ret_succeeded,
3667 "the result should be NULL if the VM did not succeed");
3668 *succeeded = ret_succeeded;
3669
3670 assert_heap_not_locked();
3671 return result;
3672 }
3673
3674 void
3675 G1CollectedHeap::doConcurrentMark() {
3676 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3677 if (!_cmThread->in_progress()) {
3678 _cmThread->set_started();
3679 CGC_lock->notify();
3680 }
3681 }
3682
3683 size_t G1CollectedHeap::pending_card_num() {
3684 size_t extra_cards = 0;
3685 JavaThread *curr = Threads::first();
3686 while (curr != NULL) {
3687 DirtyCardQueue& dcq = curr->dirty_card_queue();
3688 extra_cards += dcq.size();
3689 curr = curr->next();
3690 }
3691 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3692 size_t buffer_size = dcqs.buffer_size();
3693 size_t buffer_num = dcqs.completed_buffers_num();
3694
3695 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3696 // in bytes - not the number of 'entries'. We need to convert
3697 // into a number of cards.
3698 return (buffer_size * buffer_num + extra_cards) / oopSize;
3699 }
3700
3701 size_t G1CollectedHeap::cards_scanned() {
3702 return g1_rem_set()->cardsScanned();
3703 }
3704
3705 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3706 private:
3707 size_t _total_humongous;
3708 size_t _candidate_humongous;
3709
3710 DirtyCardQueue _dcq;
3711
3712 // We don't nominate objects with many remembered set entries, on
3713 // the assumption that such objects are likely still live.
3714 bool is_remset_small(HeapRegion* region) const {
3715 HeapRegionRemSet* const rset = region->rem_set();
3716 return G1EagerReclaimHumongousObjectsWithStaleRefs
3717 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3718 : rset->is_empty();
3719 }
3720
3721 bool is_typeArray_region(HeapRegion* region) const {
3722 return oop(region->bottom())->is_typeArray();
3723 }
3724
3725 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3726 assert(region->is_starts_humongous(), "Must start a humongous object");
3727
3728 // Candidate selection must satisfy the following constraints
3729 // while concurrent marking is in progress:
3730 //
3731 // * In order to maintain SATB invariants, an object must not be
3732 // reclaimed if it was allocated before the start of marking and
3733 // has not had its references scanned. Such an object must have
3734 // its references (including type metadata) scanned to ensure no
3735 // live objects are missed by the marking process. Objects
3736 // allocated after the start of concurrent marking don't need to
3737 // be scanned.
3738 //
3739 // * An object must not be reclaimed if it is on the concurrent
3740 // mark stack. Objects allocated after the start of concurrent
3741 // marking are never pushed on the mark stack.
3742 //
3743 // Nominating only objects allocated after the start of concurrent
3744 // marking is sufficient to meet both constraints. This may miss
3745 // some objects that satisfy the constraints, but the marking data
3746 // structures don't support efficiently performing the needed
3747 // additional tests or scrubbing of the mark stack.
3748 //
3749 // However, we presently only nominate is_typeArray() objects.
3750 // A humongous object containing references induces remembered
3751 // set entries on other regions. In order to reclaim such an
3752 // object, those remembered sets would need to be cleaned up.
3753 //
3754 // We also treat is_typeArray() objects specially, allowing them
3755 // to be reclaimed even if allocated before the start of
3756 // concurrent mark. For this we rely on mark stack insertion to
3757 // exclude is_typeArray() objects, preventing reclaiming an object
3758 // that is in the mark stack. We also rely on the metadata for
3759 // such objects to be built-in and so ensured to be kept live.
3760 // Frequent allocation and drop of large binary blobs is an
3761 // important use case for eager reclaim, and this special handling
3762 // may reduce needed headroom.
3763
3764 return is_typeArray_region(region) && is_remset_small(region);
3765 }
3766
3767 public:
3768 RegisterHumongousWithInCSetFastTestClosure()
3769 : _total_humongous(0),
3770 _candidate_humongous(0),
3771 _dcq(&JavaThread::dirty_card_queue_set()) {
3772 }
3773
3774 virtual bool doHeapRegion(HeapRegion* r) {
3775 if (!r->is_starts_humongous()) {
3776 return false;
3777 }
3778 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3779
3780 bool is_candidate = humongous_region_is_candidate(g1h, r);
3781 uint rindex = r->hrm_index();
3782 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3783 if (is_candidate) {
3784 _candidate_humongous++;
3785 g1h->register_humongous_region_with_cset(rindex);
3786 // Is_candidate already filters out humongous object with large remembered sets.
3787 // If we have a humongous object with a few remembered sets, we simply flush these
3788 // remembered set entries into the DCQS. That will result in automatic
3789 // re-evaluation of their remembered set entries during the following evacuation
3790 // phase.
3791 if (!r->rem_set()->is_empty()) {
3792 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3793 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3794 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3795 HeapRegionRemSetIterator hrrs(r->rem_set());
3796 size_t card_index;
3797 while (hrrs.has_next(card_index)) {
3798 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3799 // The remembered set might contain references to already freed
3800 // regions. Filter out such entries to avoid failing card table
3801 // verification.
3802 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3803 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3804 *card_ptr = CardTableModRefBS::dirty_card_val();
3805 _dcq.enqueue(card_ptr);
3806 }
3807 }
3808 }
3809 r->rem_set()->clear_locked();
3810 }
3811 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3812 }
3813 _total_humongous++;
3814
3815 return false;
3816 }
3817
3818 size_t total_humongous() const { return _total_humongous; }
3819 size_t candidate_humongous() const { return _candidate_humongous; }
3820
3821 void flush_rem_set_entries() { _dcq.flush(); }
3822 };
3823
3824 void G1CollectedHeap::register_humongous_regions_with_cset() {
3825 if (!G1EagerReclaimHumongousObjects) {
3826 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3827 return;
3828 }
3829 double time = os::elapsed_counter();
3830
3831 // Collect reclaim candidate information and register candidates with cset.
3832 RegisterHumongousWithInCSetFastTestClosure cl;
3833 heap_region_iterate(&cl);
3834
3835 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3836 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3837 cl.total_humongous(),
3838 cl.candidate_humongous());
3839 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3840
3841 // Finally flush all remembered set entries to re-check into the global DCQS.
3842 cl.flush_rem_set_entries();
3843 }
3844
3845 void G1CollectedHeap::setup_surviving_young_words() {
3846 assert(_surviving_young_words == NULL, "pre-condition");
3847 uint array_length = g1_policy()->young_cset_region_length();
3848 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3849 if (_surviving_young_words == NULL) {
3850 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3851 "Not enough space for young surv words summary.");
3852 }
3853 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3854 #ifdef ASSERT
3855 for (uint i = 0; i < array_length; ++i) {
3856 assert( _surviving_young_words[i] == 0, "memset above" );
3857 }
3858 #endif // !ASSERT
3859 }
3860
3861 void G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3862 assert_at_safepoint(true);
3863 uint array_length = g1_policy()->young_cset_region_length();
3864 for (uint i = 0; i < array_length; ++i) {
3865 _surviving_young_words[i] += surv_young_words[i];
3866 }
3867 }
3868
3869 void G1CollectedHeap::cleanup_surviving_young_words() {
3870 guarantee( _surviving_young_words != NULL, "pre-condition" );
3871 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3872 _surviving_young_words = NULL;
3873 }
3874
3875 #ifdef ASSERT
3876 class VerifyCSetClosure: public HeapRegionClosure {
3877 public:
3878 bool doHeapRegion(HeapRegion* hr) {
3879 // Here we check that the CSet region's RSet is ready for parallel
3880 // iteration. The fields that we'll verify are only manipulated
3881 // when the region is part of a CSet and is collected. Afterwards,
3882 // we reset these fields when we clear the region's RSet (when the
3883 // region is freed) so they are ready when the region is
3884 // re-allocated. The only exception to this is if there's an
3885 // evacuation failure and instead of freeing the region we leave
3886 // it in the heap. In that case, we reset these fields during
3887 // evacuation failure handling.
3888 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3889
3890 // Here's a good place to add any other checks we'd like to
3891 // perform on CSet regions.
3892 return false;
3893 }
3894 };
3895 #endif // ASSERT
3896
3897 uint G1CollectedHeap::num_task_queues() const {
3898 return _task_queues->size();
3899 }
3900
3901 #if TASKQUEUE_STATS
3902 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3903 st->print_raw_cr("GC Task Stats");
3904 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3905 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3906 }
3907
3908 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3909 print_taskqueue_stats_hdr(st);
3910
3911 TaskQueueStats totals;
3912 const uint n = num_task_queues();
3913 for (uint i = 0; i < n; ++i) {
3914 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3915 totals += task_queue(i)->stats;
3916 }
3917 st->print_raw("tot "); totals.print(st); st->cr();
3918
3919 DEBUG_ONLY(totals.verify());
3920 }
3921
3922 void G1CollectedHeap::reset_taskqueue_stats() {
3923 const uint n = num_task_queues();
3924 for (uint i = 0; i < n; ++i) {
3925 task_queue(i)->stats.reset();
3926 }
3927 }
3928 #endif // TASKQUEUE_STATS
3929
3930 void G1CollectedHeap::log_gc_header() {
3931 if (!G1Log::fine()) {
3932 return;
3933 }
3934
3935 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3936
3937 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3938 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3939 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3940
3941 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3942 }
3943
3944 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3945 if (!G1Log::fine()) {
3946 return;
3947 }
3948
3949 if (G1Log::finer()) {
3950 if (evacuation_failed()) {
3951 gclog_or_tty->print(" (to-space exhausted)");
3952 }
3953 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3954 g1_policy()->phase_times()->note_gc_end();
3955 g1_policy()->phase_times()->print(pause_time_sec);
3956 g1_policy()->print_detailed_heap_transition();
3957 } else {
3958 if (evacuation_failed()) {
3959 gclog_or_tty->print("--");
3960 }
3961 g1_policy()->print_heap_transition();
3962 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3963 }
3964 gclog_or_tty->flush();
3965 }
3966
3967 void G1CollectedHeap::wait_for_root_region_scanning() {
3968 double scan_wait_start = os::elapsedTime();
3969 // We have to wait until the CM threads finish scanning the
3970 // root regions as it's the only way to ensure that all the
3971 // objects on them have been correctly scanned before we start
3972 // moving them during the GC.
3973 bool waited = _cm->root_regions()->wait_until_scan_finished();
3974 double wait_time_ms = 0.0;
3975 if (waited) {
3976 double scan_wait_end = os::elapsedTime();
3977 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3978 }
3979 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3980 }
3981
3982 bool
3983 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3984 assert_at_safepoint(true /* should_be_vm_thread */);
3985 guarantee(!is_gc_active(), "collection is not reentrant");
3986
3987 if (GC_locker::check_active_before_gc()) {
3988 return false;
3989 }
3990
3991 _gc_timer_stw->register_gc_start();
3992
3993 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3994
3995 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3996 ResourceMark rm;
3997
3998 wait_for_root_region_scanning();
3999
4000 G1Log::update_level();
4001 print_heap_before_gc();
4002 trace_heap_before_gc(_gc_tracer_stw);
4003
4004 verify_region_sets_optional();
4005 verify_dirty_young_regions();
4006
4007 // This call will decide whether this pause is an initial-mark
4008 // pause. If it is, during_initial_mark_pause() will return true
4009 // for the duration of this pause.
4010 g1_policy()->decide_on_conc_mark_initiation();
4011
4012 // We do not allow initial-mark to be piggy-backed on a mixed GC.
4013 assert(!collector_state()->during_initial_mark_pause() ||
4014 collector_state()->gcs_are_young(), "sanity");
4015
4016 // We also do not allow mixed GCs during marking.
4017 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4018
4019 // Record whether this pause is an initial mark. When the current
4020 // thread has completed its logging output and it's safe to signal
4021 // the CM thread, the flag's value in the policy has been reset.
4022 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4023
4024 // Inner scope for scope based logging, timers, and stats collection
4025 {
4026 EvacuationInfo evacuation_info;
4027
4028 if (collector_state()->during_initial_mark_pause()) {
4029 // We are about to start a marking cycle, so we increment the
4030 // full collection counter.
4031 increment_old_marking_cycles_started();
4032 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4033 }
4034
4035 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4036
4037 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4038
4039 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4040 workers()->active_workers(),
4041 Threads::number_of_non_daemon_threads());
4042 workers()->set_active_workers(active_workers);
4043
4044 double pause_start_sec = os::elapsedTime();
4045 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4046 log_gc_header();
4047
4048 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4049 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4050
4051 // If the secondary_free_list is not empty, append it to the
4052 // free_list. No need to wait for the cleanup operation to finish;
4053 // the region allocation code will check the secondary_free_list
4054 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4055 // set, skip this step so that the region allocation code has to
4056 // get entries from the secondary_free_list.
4057 if (!G1StressConcRegionFreeing) {
4058 append_secondary_free_list_if_not_empty_with_lock();
4059 }
4060
4061 assert(check_young_list_well_formed(), "young list should be well formed");
4062
4063 // Don't dynamically change the number of GC threads this early. A value of
4064 // 0 is used to indicate serial work. When parallel work is done,
4065 // it will be set.
4066
4067 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4068 IsGCActiveMark x;
4069
4070 gc_prologue(false);
4071 increment_total_collections(false /* full gc */);
4072 increment_gc_time_stamp();
4073
4074 verify_before_gc();
4075
4076 check_bitmaps("GC Start");
4077
4078 COMPILER2_PRESENT(DerivedPointerTable::clear());
4079
4080 // Please see comment in g1CollectedHeap.hpp and
4081 // G1CollectedHeap::ref_processing_init() to see how
4082 // reference processing currently works in G1.
4083
4084 // Enable discovery in the STW reference processor
4085 ref_processor_stw()->enable_discovery();
4086
4087 {
4088 // We want to temporarily turn off discovery by the
4089 // CM ref processor, if necessary, and turn it back on
4090 // on again later if we do. Using a scoped
4091 // NoRefDiscovery object will do this.
4092 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4093
4094 // Forget the current alloc region (we might even choose it to be part
4095 // of the collection set!).
4096 _allocator->release_mutator_alloc_region();
4097
4098 // We should call this after we retire the mutator alloc
4099 // region(s) so that all the ALLOC / RETIRE events are generated
4100 // before the start GC event.
4101 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4102
4103 // This timing is only used by the ergonomics to handle our pause target.
4104 // It is unclear why this should not include the full pause. We will
4105 // investigate this in CR 7178365.
4106 //
4107 // Preserving the old comment here if that helps the investigation:
4108 //
4109 // The elapsed time induced by the start time below deliberately elides
4110 // the possible verification above.
4111 double sample_start_time_sec = os::elapsedTime();
4112
4113 #if YOUNG_LIST_VERBOSE
4114 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4115 _young_list->print();
4116 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4117 #endif // YOUNG_LIST_VERBOSE
4118
4119 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4120
4121 #if YOUNG_LIST_VERBOSE
4122 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4123 _young_list->print();
4124 #endif // YOUNG_LIST_VERBOSE
4125
4126 if (collector_state()->during_initial_mark_pause()) {
4127 concurrent_mark()->checkpointRootsInitialPre();
4128 }
4129
4130 #if YOUNG_LIST_VERBOSE
4131 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4132 _young_list->print();
4133 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4134 #endif // YOUNG_LIST_VERBOSE
4135
4136 g1_policy()->finalize_cset(target_pause_time_ms);
4137
4138 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4139
4140 register_humongous_regions_with_cset();
4141
4142 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4143
4144 _cm->note_start_of_gc();
4145 // We call this after finalize_cset() to
4146 // ensure that the CSet has been finalized.
4147 _cm->verify_no_cset_oops();
4148
4149 if (_hr_printer.is_active()) {
4150 HeapRegion* hr = g1_policy()->collection_set();
4151 while (hr != NULL) {
4152 _hr_printer.cset(hr);
4153 hr = hr->next_in_collection_set();
4154 }
4155 }
4156
4157 #ifdef ASSERT
4158 VerifyCSetClosure cl;
4159 collection_set_iterate(&cl);
4160 #endif // ASSERT
4161
4162 setup_surviving_young_words();
4163
4164 // Initialize the GC alloc regions.
4165 _allocator->init_gc_alloc_regions(evacuation_info);
4166
4167 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers());
4168 // Actually do the work...
4169 evacuate_collection_set(evacuation_info, &per_thread_states);
4170
4171 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4172
4173 eagerly_reclaim_humongous_regions();
4174
4175 g1_policy()->clear_collection_set();
4176
4177 cleanup_surviving_young_words();
4178
4179 // Start a new incremental collection set for the next pause.
4180 g1_policy()->start_incremental_cset_building();
4181
4182 clear_cset_fast_test();
4183
4184 _young_list->reset_sampled_info();
4185
4186 // Don't check the whole heap at this point as the
4187 // GC alloc regions from this pause have been tagged
4188 // as survivors and moved on to the survivor list.
4189 // Survivor regions will fail the !is_young() check.
4190 assert(check_young_list_empty(false /* check_heap */),
4191 "young list should be empty");
4192
4193 #if YOUNG_LIST_VERBOSE
4194 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4195 _young_list->print();
4196 #endif // YOUNG_LIST_VERBOSE
4197
4198 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4199 _young_list->first_survivor_region(),
4200 _young_list->last_survivor_region());
4201
4202 _young_list->reset_auxilary_lists();
4203
4204 if (evacuation_failed()) {
4205 set_used(recalculate_used());
4206 if (_archive_allocator != NULL) {
4207 _archive_allocator->clear_used();
4208 }
4209 for (uint i = 0; i < ParallelGCThreads; i++) {
4210 if (_evacuation_failed_info_array[i].has_failed()) {
4211 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4212 }
4213 }
4214 } else {
4215 // The "used" of the the collection set have already been subtracted
4216 // when they were freed. Add in the bytes evacuated.
4217 increase_used(g1_policy()->bytes_copied_during_gc());
4218 }
4219
4220 if (collector_state()->during_initial_mark_pause()) {
4221 // We have to do this before we notify the CM threads that
4222 // they can start working to make sure that all the
4223 // appropriate initialization is done on the CM object.
4224 concurrent_mark()->checkpointRootsInitialPost();
4225 collector_state()->set_mark_in_progress(true);
4226 // Note that we don't actually trigger the CM thread at
4227 // this point. We do that later when we're sure that
4228 // the current thread has completed its logging output.
4229 }
4230
4231 allocate_dummy_regions();
4232
4233 #if YOUNG_LIST_VERBOSE
4234 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4235 _young_list->print();
4236 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4237 #endif // YOUNG_LIST_VERBOSE
4238
4239 _allocator->init_mutator_alloc_region();
4240
4241 {
4242 size_t expand_bytes = g1_policy()->expansion_amount();
4243 if (expand_bytes > 0) {
4244 size_t bytes_before = capacity();
4245 // No need for an ergo verbose message here,
4246 // expansion_amount() does this when it returns a value > 0.
4247 if (!expand(expand_bytes)) {
4248 // We failed to expand the heap. Cannot do anything about it.
4249 }
4250 }
4251 }
4252
4253 // We redo the verification but now wrt to the new CSet which
4254 // has just got initialized after the previous CSet was freed.
4255 _cm->verify_no_cset_oops();
4256 _cm->note_end_of_gc();
4257
4258 // This timing is only used by the ergonomics to handle our pause target.
4259 // It is unclear why this should not include the full pause. We will
4260 // investigate this in CR 7178365.
4261 double sample_end_time_sec = os::elapsedTime();
4262 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4263 g1_policy()->record_collection_pause_end(pause_time_ms);
4264
4265 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4266 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4267
4268 MemoryService::track_memory_usage();
4269
4270 // In prepare_for_verify() below we'll need to scan the deferred
4271 // update buffers to bring the RSets up-to-date if
4272 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4273 // the update buffers we'll probably need to scan cards on the
4274 // regions we just allocated to (i.e., the GC alloc
4275 // regions). However, during the last GC we called
4276 // set_saved_mark() on all the GC alloc regions, so card
4277 // scanning might skip the [saved_mark_word()...top()] area of
4278 // those regions (i.e., the area we allocated objects into
4279 // during the last GC). But it shouldn't. Given that
4280 // saved_mark_word() is conditional on whether the GC time stamp
4281 // on the region is current or not, by incrementing the GC time
4282 // stamp here we invalidate all the GC time stamps on all the
4283 // regions and saved_mark_word() will simply return top() for
4284 // all the regions. This is a nicer way of ensuring this rather
4285 // than iterating over the regions and fixing them. In fact, the
4286 // GC time stamp increment here also ensures that
4287 // saved_mark_word() will return top() between pauses, i.e.,
4288 // during concurrent refinement. So we don't need the
4289 // is_gc_active() check to decided which top to use when
4290 // scanning cards (see CR 7039627).
4291 increment_gc_time_stamp();
4292
4293 verify_after_gc();
4294 check_bitmaps("GC End");
4295
4296 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4297 ref_processor_stw()->verify_no_references_recorded();
4298
4299 // CM reference discovery will be re-enabled if necessary.
4300 }
4301
4302 // We should do this after we potentially expand the heap so
4303 // that all the COMMIT events are generated before the end GC
4304 // event, and after we retire the GC alloc regions so that all
4305 // RETIRE events are generated before the end GC event.
4306 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4307
4308 #ifdef TRACESPINNING
4309 ParallelTaskTerminator::print_termination_counts();
4310 #endif
4311
4312 gc_epilogue(false);
4313 }
4314
4315 // Print the remainder of the GC log output.
4316 log_gc_footer(os::elapsedTime() - pause_start_sec);
4317
4318 // It is not yet to safe to tell the concurrent mark to
4319 // start as we have some optional output below. We don't want the
4320 // output from the concurrent mark thread interfering with this
4321 // logging output either.
4322
4323 _hrm.verify_optional();
4324 verify_region_sets_optional();
4325
4326 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4327 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4328
4329 print_heap_after_gc();
4330 trace_heap_after_gc(_gc_tracer_stw);
4331
4332 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4333 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4334 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4335 // before any GC notifications are raised.
4336 g1mm()->update_sizes();
4337
4338 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4339 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4340 _gc_timer_stw->register_gc_end();
4341 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4342 }
4343 // It should now be safe to tell the concurrent mark thread to start
4344 // without its logging output interfering with the logging output
4345 // that came from the pause.
4346
4347 if (should_start_conc_mark) {
4348 // CAUTION: after the doConcurrentMark() call below,
4349 // the concurrent marking thread(s) could be running
4350 // concurrently with us. Make sure that anything after
4351 // this point does not assume that we are the only GC thread
4352 // running. Note: of course, the actual marking work will
4353 // not start until the safepoint itself is released in
4354 // SuspendibleThreadSet::desynchronize().
4355 doConcurrentMark();
4356 }
4357
4358 return true;
4359 }
4360
4361 void G1CollectedHeap::remove_self_forwarding_pointers() {
4362 double remove_self_forwards_start = os::elapsedTime();
4363
4364 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4365 workers()->run_task(&rsfp_task);
4366
4367 // Now restore saved marks, if any.
4368 for (uint i = 0; i < ParallelGCThreads; i++) {
4369 OopAndMarkOopStack& cur = _preserved_objs[i];
4370 while (!cur.is_empty()) {
4371 OopAndMarkOop elem = cur.pop();
4372 elem.set_mark();
4373 }
4374 cur.clear(true);
4375 }
4376
4377 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4378 }
4379
4380 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4381 if (!_evacuation_failed) {
4382 _evacuation_failed = true;
4383 }
4384
4385 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4386
4387 // We want to call the "for_promotion_failure" version only in the
4388 // case of a promotion failure.
4389 if (m->must_be_preserved_for_promotion_failure(obj)) {
4390 OopAndMarkOop elem(obj, m);
4391 _preserved_objs[worker_id].push(elem);
4392 }
4393 }
4394
4395 void G1ParCopyHelper::mark_object(oop obj) {
4396 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4397
4398 // We know that the object is not moving so it's safe to read its size.
4399 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4400 }
4401
4402 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4403 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4404 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4405 assert(from_obj != to_obj, "should not be self-forwarded");
4406
4407 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4408 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4409
4410 // The object might be in the process of being copied by another
4411 // worker so we cannot trust that its to-space image is
4412 // well-formed. So we have to read its size from its from-space
4413 // image which we know should not be changing.
4414 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4415 }
4416
4417 template <class T>
4418 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4419 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4420 _scanned_klass->record_modified_oops();
4421 }
4422 }
4423
4424 template <G1Barrier barrier, G1Mark do_mark_object>
4425 template <class T>
4426 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4427 T heap_oop = oopDesc::load_heap_oop(p);
4428
4429 if (oopDesc::is_null(heap_oop)) {
4430 return;
4431 }
4432
4433 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4434
4435 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4436
4437 const InCSetState state = _g1->in_cset_state(obj);
4438 if (state.is_in_cset()) {
4439 oop forwardee;
4440 markOop m = obj->mark();
4441 if (m->is_marked()) {
4442 forwardee = (oop) m->decode_pointer();
4443 } else {
4444 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4445 }
4446 assert(forwardee != NULL, "forwardee should not be NULL");
4447 oopDesc::encode_store_heap_oop(p, forwardee);
4448 if (do_mark_object != G1MarkNone && forwardee != obj) {
4449 // If the object is self-forwarded we don't need to explicitly
4450 // mark it, the evacuation failure protocol will do so.
4451 mark_forwarded_object(obj, forwardee);
4452 }
4453
4454 if (barrier == G1BarrierKlass) {
4455 do_klass_barrier(p, forwardee);
4456 }
4457 } else {
4458 if (state.is_humongous()) {
4459 _g1->set_humongous_is_live(obj);
4460 }
4461 // The object is not in collection set. If we're a root scanning
4462 // closure during an initial mark pause then attempt to mark the object.
4463 if (do_mark_object == G1MarkFromRoot) {
4464 mark_object(obj);
4465 }
4466 }
4467 }
4468
4469 class G1ParEvacuateFollowersClosure : public VoidClosure {
4470 private:
4471 double _start_term;
4472 double _term_time;
4473 size_t _term_attempts;
4474
4475 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4476 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4477 protected:
4478 G1CollectedHeap* _g1h;
4479 G1ParScanThreadState* _par_scan_state;
4480 RefToScanQueueSet* _queues;
4481 ParallelTaskTerminator* _terminator;
4482
4483 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4484 RefToScanQueueSet* queues() { return _queues; }
4485 ParallelTaskTerminator* terminator() { return _terminator; }
4486
4487 public:
4488 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4489 G1ParScanThreadState* par_scan_state,
4490 RefToScanQueueSet* queues,
4491 ParallelTaskTerminator* terminator)
4492 : _g1h(g1h), _par_scan_state(par_scan_state),
4493 _queues(queues), _terminator(terminator),
4494 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4495
4496 void do_void();
4497
4498 double term_time() const { return _term_time; }
4499 size_t term_attempts() const { return _term_attempts; }
4500
4501 private:
4502 inline bool offer_termination();
4503 };
4504
4505 bool G1ParEvacuateFollowersClosure::offer_termination() {
4506 G1ParScanThreadState* const pss = par_scan_state();
4507 start_term_time();
4508 const bool res = terminator()->offer_termination();
4509 end_term_time();
4510 return res;
4511 }
4512
4513 void G1ParEvacuateFollowersClosure::do_void() {
4514 G1ParScanThreadState* const pss = par_scan_state();
4515 pss->trim_queue();
4516 do {
4517 pss->steal_and_trim_queue(queues());
4518 } while (!offer_termination());
4519 }
4520
4521 class G1KlassScanClosure : public KlassClosure {
4522 G1ParCopyHelper* _closure;
4523 bool _process_only_dirty;
4524 int _count;
4525 public:
4526 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4527 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4528 void do_klass(Klass* klass) {
4529 // If the klass has not been dirtied we know that there's
4530 // no references into the young gen and we can skip it.
4531 if (!_process_only_dirty || klass->has_modified_oops()) {
4532 // Clean the klass since we're going to scavenge all the metadata.
4533 klass->clear_modified_oops();
4534
4535 // Tell the closure that this klass is the Klass to scavenge
4536 // and is the one to dirty if oops are left pointing into the young gen.
4537 _closure->set_scanned_klass(klass);
4538
4539 klass->oops_do(_closure);
4540
4541 _closure->set_scanned_klass(NULL);
4542 }
4543 _count++;
4544 }
4545 };
4546
4547 class G1ParTask : public AbstractGangTask {
4548 protected:
4549 G1CollectedHeap* _g1h;
4550 G1ParScanThreadStateSet* _pss;
4551 RefToScanQueueSet* _queues;
4552 G1RootProcessor* _root_processor;
4553 ParallelTaskTerminator _terminator;
4554 uint _n_workers;
4555
4556 public:
4557 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4558 : AbstractGangTask("G1 collection"),
4559 _g1h(g1h),
4560 _pss(per_thread_states),
4561 _queues(task_queues),
4562 _root_processor(root_processor),
4563 _terminator(n_workers, _queues),
4564 _n_workers(n_workers)
4565 {}
4566
4567 RefToScanQueueSet* queues() { return _queues; }
4568
4569 RefToScanQueue *work_queue(int i) {
4570 return queues()->queue(i);
4571 }
4572
4573 ParallelTaskTerminator* terminator() { return &_terminator; }
4574
4575 // Helps out with CLD processing.
4576 //
4577 // During InitialMark we need to:
4578 // 1) Scavenge all CLDs for the young GC.
4579 // 2) Mark all objects directly reachable from strong CLDs.
4580 template <G1Mark do_mark_object>
4581 class G1CLDClosure : public CLDClosure {
4582 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4583 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4584 G1KlassScanClosure _klass_in_cld_closure;
4585 bool _claim;
4586
4587 public:
4588 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4589 bool only_young, bool claim)
4590 : _oop_closure(oop_closure),
4591 _oop_in_klass_closure(oop_closure->g1(),
4592 oop_closure->pss()),
4593 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4594 _claim(claim) {
4595
4596 }
4597
4598 void do_cld(ClassLoaderData* cld) {
4599 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4600 }
4601 };
4602
4603 void work(uint worker_id) {
4604 if (worker_id >= _n_workers) return; // no work needed this round
4605
4606 double start_sec = os::elapsedTime();
4607 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4608
4609 {
4610 ResourceMark rm;
4611 HandleMark hm;
4612
4613 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4614
4615 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4616 pss->set_ref_processor(rp);
4617
4618 bool only_young = _g1h->collector_state()->gcs_are_young();
4619
4620 // Non-IM young GC.
4621 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss);
4622 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4623 only_young, // Only process dirty klasses.
4624 false); // No need to claim CLDs.
4625 // IM young GC.
4626 // Strong roots closures.
4627 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss);
4628 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4629 false, // Process all klasses.
4630 true); // Need to claim CLDs.
4631 // Weak roots closures.
4632 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4633 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4634 false, // Process all klasses.
4635 true); // Need to claim CLDs.
4636
4637 OopClosure* strong_root_cl;
4638 OopClosure* weak_root_cl;
4639 CLDClosure* strong_cld_cl;
4640 CLDClosure* weak_cld_cl;
4641
4642 bool trace_metadata = false;
4643
4644 if (_g1h->collector_state()->during_initial_mark_pause()) {
4645 // We also need to mark copied objects.
4646 strong_root_cl = &scan_mark_root_cl;
4647 strong_cld_cl = &scan_mark_cld_cl;
4648 if (ClassUnloadingWithConcurrentMark) {
4649 weak_root_cl = &scan_mark_weak_root_cl;
4650 weak_cld_cl = &scan_mark_weak_cld_cl;
4651 trace_metadata = true;
4652 } else {
4653 weak_root_cl = &scan_mark_root_cl;
4654 weak_cld_cl = &scan_mark_cld_cl;
4655 }
4656 } else {
4657 strong_root_cl = &scan_only_root_cl;
4658 weak_root_cl = &scan_only_root_cl;
4659 strong_cld_cl = &scan_only_cld_cl;
4660 weak_cld_cl = &scan_only_cld_cl;
4661 }
4662
4663 double start_strong_roots_sec = os::elapsedTime();
4664 _root_processor->evacuate_roots(strong_root_cl,
4665 weak_root_cl,
4666 strong_cld_cl,
4667 weak_cld_cl,
4668 trace_metadata,
4669 worker_id);
4670
4671 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4672 _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4673 weak_root_cl,
4674 worker_id);
4675 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4676
4677 double term_sec = 0.0;
4678 size_t evac_term_attempts = 0;
4679 {
4680 double start = os::elapsedTime();
4681 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4682 evac.do_void();
4683
4684 evac_term_attempts = evac.term_attempts();
4685 term_sec = evac.term_time();
4686 double elapsed_sec = os::elapsedTime() - start;
4687 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4688 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4689 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4690 }
4691
4692 assert(pss->queue_is_empty(), "should be empty");
4693
4694 if (PrintTerminationStats) {
4695 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4696 size_t lab_waste;
4697 size_t lab_undo_waste;
4698 pss->waste(lab_waste, lab_undo_waste);
4699 _g1h->print_termination_stats(gclog_or_tty,
4700 worker_id,
4701 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4702 strong_roots_sec * 1000.0, /* strong roots time */
4703 term_sec * 1000.0, /* evac term time */
4704 evac_term_attempts, /* evac term attempts */
4705 lab_waste, /* alloc buffer waste */
4706 lab_undo_waste /* undo waste */
4707 );
4708 }
4709
4710 // Close the inner scope so that the ResourceMark and HandleMark
4711 // destructors are executed here and are included as part of the
4712 // "GC Worker Time".
4713 }
4714 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4715 }
4716 };
4717
4718 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4719 st->print_raw_cr("GC Termination Stats");
4720 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4721 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4722 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4723 }
4724
4725 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4726 uint worker_id,
4727 double elapsed_ms,
4728 double strong_roots_ms,
4729 double term_ms,
4730 size_t term_attempts,
4731 size_t alloc_buffer_waste,
4732 size_t undo_waste) const {
4733 st->print_cr("%3d %9.2f %9.2f %6.2f "
4734 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4735 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4736 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4737 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4738 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4739 alloc_buffer_waste * HeapWordSize / K,
4740 undo_waste * HeapWordSize / K);
4741 }
4742
4743 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4744 private:
4745 BoolObjectClosure* _is_alive;
4746 int _initial_string_table_size;
4747 int _initial_symbol_table_size;
4748
4749 bool _process_strings;
4750 int _strings_processed;
4751 int _strings_removed;
4752
4753 bool _process_symbols;
4754 int _symbols_processed;
4755 int _symbols_removed;
4756
4757 public:
4758 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4759 AbstractGangTask("String/Symbol Unlinking"),
4760 _is_alive(is_alive),
4761 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4762 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4763
4764 _initial_string_table_size = StringTable::the_table()->table_size();
4765 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4766 if (process_strings) {
4767 StringTable::clear_parallel_claimed_index();
4768 }
4769 if (process_symbols) {
4770 SymbolTable::clear_parallel_claimed_index();
4771 }
4772 }
4773
4774 ~G1StringSymbolTableUnlinkTask() {
4775 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4776 err_msg("claim value %d after unlink less than initial string table size %d",
4777 StringTable::parallel_claimed_index(), _initial_string_table_size));
4778 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4779 err_msg("claim value %d after unlink less than initial symbol table size %d",
4780 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4781
4782 if (G1TraceStringSymbolTableScrubbing) {
4783 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4784 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4785 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4786 strings_processed(), strings_removed(),
4787 symbols_processed(), symbols_removed());
4788 }
4789 }
4790
4791 void work(uint worker_id) {
4792 int strings_processed = 0;
4793 int strings_removed = 0;
4794 int symbols_processed = 0;
4795 int symbols_removed = 0;
4796 if (_process_strings) {
4797 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4798 Atomic::add(strings_processed, &_strings_processed);
4799 Atomic::add(strings_removed, &_strings_removed);
4800 }
4801 if (_process_symbols) {
4802 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4803 Atomic::add(symbols_processed, &_symbols_processed);
4804 Atomic::add(symbols_removed, &_symbols_removed);
4805 }
4806 }
4807
4808 size_t strings_processed() const { return (size_t)_strings_processed; }
4809 size_t strings_removed() const { return (size_t)_strings_removed; }
4810
4811 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4812 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4813 };
4814
4815 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4816 private:
4817 static Monitor* _lock;
4818
4819 BoolObjectClosure* const _is_alive;
4820 const bool _unloading_occurred;
4821 const uint _num_workers;
4822
4823 // Variables used to claim nmethods.
4824 nmethod* _first_nmethod;
4825 volatile nmethod* _claimed_nmethod;
4826
4827 // The list of nmethods that need to be processed by the second pass.
4828 volatile nmethod* _postponed_list;
4829 volatile uint _num_entered_barrier;
4830
4831 public:
4832 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4833 _is_alive(is_alive),
4834 _unloading_occurred(unloading_occurred),
4835 _num_workers(num_workers),
4836 _first_nmethod(NULL),
4837 _claimed_nmethod(NULL),
4838 _postponed_list(NULL),
4839 _num_entered_barrier(0)
4840 {
4841 nmethod::increase_unloading_clock();
4842 // Get first alive nmethod
4843 NMethodIterator iter = NMethodIterator();
4844 if(iter.next_alive()) {
4845 _first_nmethod = iter.method();
4846 }
4847 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4848 }
4849
4850 ~G1CodeCacheUnloadingTask() {
4851 CodeCache::verify_clean_inline_caches();
4852
4853 CodeCache::set_needs_cache_clean(false);
4854 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4855
4856 CodeCache::verify_icholder_relocations();
4857 }
4858
4859 private:
4860 void add_to_postponed_list(nmethod* nm) {
4861 nmethod* old;
4862 do {
4863 old = (nmethod*)_postponed_list;
4864 nm->set_unloading_next(old);
4865 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4866 }
4867
4868 void clean_nmethod(nmethod* nm) {
4869 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4870
4871 if (postponed) {
4872 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4873 add_to_postponed_list(nm);
4874 }
4875
4876 // Mark that this thread has been cleaned/unloaded.
4877 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4878 nm->set_unloading_clock(nmethod::global_unloading_clock());
4879 }
4880
4881 void clean_nmethod_postponed(nmethod* nm) {
4882 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4883 }
4884
4885 static const int MaxClaimNmethods = 16;
4886
4887 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4888 nmethod* first;
4889 NMethodIterator last;
4890
4891 do {
4892 *num_claimed_nmethods = 0;
4893
4894 first = (nmethod*)_claimed_nmethod;
4895 last = NMethodIterator(first);
4896
4897 if (first != NULL) {
4898
4899 for (int i = 0; i < MaxClaimNmethods; i++) {
4900 if (!last.next_alive()) {
4901 break;
4902 }
4903 claimed_nmethods[i] = last.method();
4904 (*num_claimed_nmethods)++;
4905 }
4906 }
4907
4908 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4909 }
4910
4911 nmethod* claim_postponed_nmethod() {
4912 nmethod* claim;
4913 nmethod* next;
4914
4915 do {
4916 claim = (nmethod*)_postponed_list;
4917 if (claim == NULL) {
4918 return NULL;
4919 }
4920
4921 next = claim->unloading_next();
4922
4923 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4924
4925 return claim;
4926 }
4927
4928 public:
4929 // Mark that we're done with the first pass of nmethod cleaning.
4930 void barrier_mark(uint worker_id) {
4931 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4932 _num_entered_barrier++;
4933 if (_num_entered_barrier == _num_workers) {
4934 ml.notify_all();
4935 }
4936 }
4937
4938 // See if we have to wait for the other workers to
4939 // finish their first-pass nmethod cleaning work.
4940 void barrier_wait(uint worker_id) {
4941 if (_num_entered_barrier < _num_workers) {
4942 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4943 while (_num_entered_barrier < _num_workers) {
4944 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4945 }
4946 }
4947 }
4948
4949 // Cleaning and unloading of nmethods. Some work has to be postponed
4950 // to the second pass, when we know which nmethods survive.
4951 void work_first_pass(uint worker_id) {
4952 // The first nmethods is claimed by the first worker.
4953 if (worker_id == 0 && _first_nmethod != NULL) {
4954 clean_nmethod(_first_nmethod);
4955 _first_nmethod = NULL;
4956 }
4957
4958 int num_claimed_nmethods;
4959 nmethod* claimed_nmethods[MaxClaimNmethods];
4960
4961 while (true) {
4962 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4963
4964 if (num_claimed_nmethods == 0) {
4965 break;
4966 }
4967
4968 for (int i = 0; i < num_claimed_nmethods; i++) {
4969 clean_nmethod(claimed_nmethods[i]);
4970 }
4971 }
4972 }
4973
4974 void work_second_pass(uint worker_id) {
4975 nmethod* nm;
4976 // Take care of postponed nmethods.
4977 while ((nm = claim_postponed_nmethod()) != NULL) {
4978 clean_nmethod_postponed(nm);
4979 }
4980 }
4981 };
4982
4983 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4984
4985 class G1KlassCleaningTask : public StackObj {
4986 BoolObjectClosure* _is_alive;
4987 volatile jint _clean_klass_tree_claimed;
4988 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4989
4990 public:
4991 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4992 _is_alive(is_alive),
4993 _clean_klass_tree_claimed(0),
4994 _klass_iterator() {
4995 }
4996
4997 private:
4998 bool claim_clean_klass_tree_task() {
4999 if (_clean_klass_tree_claimed) {
5000 return false;
5001 }
5002
5003 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5004 }
5005
5006 InstanceKlass* claim_next_klass() {
5007 Klass* klass;
5008 do {
5009 klass =_klass_iterator.next_klass();
5010 } while (klass != NULL && !klass->oop_is_instance());
5011
5012 return (InstanceKlass*)klass;
5013 }
5014
5015 public:
5016
5017 void clean_klass(InstanceKlass* ik) {
5018 ik->clean_implementors_list(_is_alive);
5019 ik->clean_method_data(_is_alive);
5020
5021 // G1 specific cleanup work that has
5022 // been moved here to be done in parallel.
5023 ik->clean_dependent_nmethods();
5024 }
5025
5026 void work() {
5027 ResourceMark rm;
5028
5029 // One worker will clean the subklass/sibling klass tree.
5030 if (claim_clean_klass_tree_task()) {
5031 Klass::clean_subklass_tree(_is_alive);
5032 }
5033
5034 // All workers will help cleaning the classes,
5035 InstanceKlass* klass;
5036 while ((klass = claim_next_klass()) != NULL) {
5037 clean_klass(klass);
5038 }
5039 }
5040 };
5041
5042 // To minimize the remark pause times, the tasks below are done in parallel.
5043 class G1ParallelCleaningTask : public AbstractGangTask {
5044 private:
5045 G1StringSymbolTableUnlinkTask _string_symbol_task;
5046 G1CodeCacheUnloadingTask _code_cache_task;
5047 G1KlassCleaningTask _klass_cleaning_task;
5048
5049 public:
5050 // The constructor is run in the VMThread.
5051 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5052 AbstractGangTask("Parallel Cleaning"),
5053 _string_symbol_task(is_alive, process_strings, process_symbols),
5054 _code_cache_task(num_workers, is_alive, unloading_occurred),
5055 _klass_cleaning_task(is_alive) {
5056 }
5057
5058 // The parallel work done by all worker threads.
5059 void work(uint worker_id) {
5060 // Do first pass of code cache cleaning.
5061 _code_cache_task.work_first_pass(worker_id);
5062
5063 // Let the threads mark that the first pass is done.
5064 _code_cache_task.barrier_mark(worker_id);
5065
5066 // Clean the Strings and Symbols.
5067 _string_symbol_task.work(worker_id);
5068
5069 // Wait for all workers to finish the first code cache cleaning pass.
5070 _code_cache_task.barrier_wait(worker_id);
5071
5072 // Do the second code cache cleaning work, which realize on
5073 // the liveness information gathered during the first pass.
5074 _code_cache_task.work_second_pass(worker_id);
5075
5076 // Clean all klasses that were not unloaded.
5077 _klass_cleaning_task.work();
5078 }
5079 };
5080
5081
5082 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5083 bool process_strings,
5084 bool process_symbols,
5085 bool class_unloading_occurred) {
5086 uint n_workers = workers()->active_workers();
5087
5088 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5089 n_workers, class_unloading_occurred);
5090 workers()->run_task(&g1_unlink_task);
5091 }
5092
5093 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5094 bool process_strings, bool process_symbols) {
5095 {
5096 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5097 workers()->run_task(&g1_unlink_task);
5098 }
5099
5100 if (G1StringDedup::is_enabled()) {
5101 G1StringDedup::unlink(is_alive);
5102 }
5103 }
5104
5105 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5106 private:
5107 DirtyCardQueueSet* _queue;
5108 public:
5109 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5110
5111 virtual void work(uint worker_id) {
5112 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5113 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5114
5115 RedirtyLoggedCardTableEntryClosure cl;
5116 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5117
5118 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5119 }
5120 };
5121
5122 void G1CollectedHeap::redirty_logged_cards() {
5123 double redirty_logged_cards_start = os::elapsedTime();
5124
5125 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5126 dirty_card_queue_set().reset_for_par_iteration();
5127 workers()->run_task(&redirty_task);
5128
5129 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5130 dcq.merge_bufferlists(&dirty_card_queue_set());
5131 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5132
5133 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5134 }
5135
5136 // Weak Reference Processing support
5137
5138 // An always "is_alive" closure that is used to preserve referents.
5139 // If the object is non-null then it's alive. Used in the preservation
5140 // of referent objects that are pointed to by reference objects
5141 // discovered by the CM ref processor.
5142 class G1AlwaysAliveClosure: public BoolObjectClosure {
5143 G1CollectedHeap* _g1;
5144 public:
5145 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5146 bool do_object_b(oop p) {
5147 if (p != NULL) {
5148 return true;
5149 }
5150 return false;
5151 }
5152 };
5153
5154 bool G1STWIsAliveClosure::do_object_b(oop p) {
5155 // An object is reachable if it is outside the collection set,
5156 // or is inside and copied.
5157 return !_g1->is_in_cset(p) || p->is_forwarded();
5158 }
5159
5160 // Non Copying Keep Alive closure
5161 class G1KeepAliveClosure: public OopClosure {
5162 G1CollectedHeap* _g1;
5163 public:
5164 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5165 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5166 void do_oop(oop* p) {
5167 oop obj = *p;
5168 assert(obj != NULL, "the caller should have filtered out NULL values");
5169
5170 const InCSetState cset_state = _g1->in_cset_state(obj);
5171 if (!cset_state.is_in_cset_or_humongous()) {
5172 return;
5173 }
5174 if (cset_state.is_in_cset()) {
5175 assert( obj->is_forwarded(), "invariant" );
5176 *p = obj->forwardee();
5177 } else {
5178 assert(!obj->is_forwarded(), "invariant" );
5179 assert(cset_state.is_humongous(),
5180 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5181 _g1->set_humongous_is_live(obj);
5182 }
5183 }
5184 };
5185
5186 // Copying Keep Alive closure - can be called from both
5187 // serial and parallel code as long as different worker
5188 // threads utilize different G1ParScanThreadState instances
5189 // and different queues.
5190
5191 class G1CopyingKeepAliveClosure: public OopClosure {
5192 G1CollectedHeap* _g1h;
5193 OopClosure* _copy_non_heap_obj_cl;
5194 G1ParScanThreadState* _par_scan_state;
5195
5196 public:
5197 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5198 OopClosure* non_heap_obj_cl,
5199 G1ParScanThreadState* pss):
5200 _g1h(g1h),
5201 _copy_non_heap_obj_cl(non_heap_obj_cl),
5202 _par_scan_state(pss)
5203 {}
5204
5205 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5206 virtual void do_oop( oop* p) { do_oop_work(p); }
5207
5208 template <class T> void do_oop_work(T* p) {
5209 oop obj = oopDesc::load_decode_heap_oop(p);
5210
5211 if (_g1h->is_in_cset_or_humongous(obj)) {
5212 // If the referent object has been forwarded (either copied
5213 // to a new location or to itself in the event of an
5214 // evacuation failure) then we need to update the reference
5215 // field and, if both reference and referent are in the G1
5216 // heap, update the RSet for the referent.
5217 //
5218 // If the referent has not been forwarded then we have to keep
5219 // it alive by policy. Therefore we have copy the referent.
5220 //
5221 // If the reference field is in the G1 heap then we can push
5222 // on the PSS queue. When the queue is drained (after each
5223 // phase of reference processing) the object and it's followers
5224 // will be copied, the reference field set to point to the
5225 // new location, and the RSet updated. Otherwise we need to
5226 // use the the non-heap or metadata closures directly to copy
5227 // the referent object and update the pointer, while avoiding
5228 // updating the RSet.
5229
5230 if (_g1h->is_in_g1_reserved(p)) {
5231 _par_scan_state->push_on_queue(p);
5232 } else {
5233 assert(!Metaspace::contains((const void*)p),
5234 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5235 _copy_non_heap_obj_cl->do_oop(p);
5236 }
5237 }
5238 }
5239 };
5240
5241 // Serial drain queue closure. Called as the 'complete_gc'
5242 // closure for each discovered list in some of the
5243 // reference processing phases.
5244
5245 class G1STWDrainQueueClosure: public VoidClosure {
5246 protected:
5247 G1CollectedHeap* _g1h;
5248 G1ParScanThreadState* _par_scan_state;
5249
5250 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5251
5252 public:
5253 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5254 _g1h(g1h),
5255 _par_scan_state(pss)
5256 { }
5257
5258 void do_void() {
5259 G1ParScanThreadState* const pss = par_scan_state();
5260 pss->trim_queue();
5261 }
5262 };
5263
5264 // Parallel Reference Processing closures
5265
5266 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5267 // processing during G1 evacuation pauses.
5268
5269 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5270 private:
5271 G1CollectedHeap* _g1h;
5272 G1ParScanThreadStateSet* _pss;
5273 RefToScanQueueSet* _queues;
5274 WorkGang* _workers;
5275 uint _active_workers;
5276
5277 public:
5278 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5279 G1ParScanThreadStateSet* per_thread_states,
5280 WorkGang* workers,
5281 RefToScanQueueSet *task_queues,
5282 uint n_workers) :
5283 _g1h(g1h),
5284 _pss(per_thread_states),
5285 _queues(task_queues),
5286 _workers(workers),
5287 _active_workers(n_workers)
5288 {
5289 assert(n_workers > 0, "shouldn't call this otherwise");
5290 }
5291
5292 // Executes the given task using concurrent marking worker threads.
5293 virtual void execute(ProcessTask& task);
5294 virtual void execute(EnqueueTask& task);
5295 };
5296
5297 // Gang task for possibly parallel reference processing
5298
5299 class G1STWRefProcTaskProxy: public AbstractGangTask {
5300 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5301 ProcessTask& _proc_task;
5302 G1CollectedHeap* _g1h;
5303 G1ParScanThreadStateSet* _pss;
5304 RefToScanQueueSet* _task_queues;
5305 ParallelTaskTerminator* _terminator;
5306
5307 public:
5308 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5309 G1CollectedHeap* g1h,
5310 G1ParScanThreadStateSet* per_thread_states,
5311 RefToScanQueueSet *task_queues,
5312 ParallelTaskTerminator* terminator) :
5313 AbstractGangTask("Process reference objects in parallel"),
5314 _proc_task(proc_task),
5315 _g1h(g1h),
5316 _pss(per_thread_states),
5317 _task_queues(task_queues),
5318 _terminator(terminator)
5319 {}
5320
5321 virtual void work(uint worker_id) {
5322 // The reference processing task executed by a single worker.
5323 ResourceMark rm;
5324 HandleMark hm;
5325
5326 G1STWIsAliveClosure is_alive(_g1h);
5327
5328 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5329 pss->set_ref_processor(NULL);
5330
5331 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5332
5333 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5334
5335 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5336
5337 if (_g1h->collector_state()->during_initial_mark_pause()) {
5338 // We also need to mark copied objects.
5339 copy_non_heap_cl = ©_mark_non_heap_cl;
5340 }
5341
5342 // Keep alive closure.
5343 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5344
5345 // Complete GC closure
5346 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5347
5348 // Call the reference processing task's work routine.
5349 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5350
5351 // Note we cannot assert that the refs array is empty here as not all
5352 // of the processing tasks (specifically phase2 - pp2_work) execute
5353 // the complete_gc closure (which ordinarily would drain the queue) so
5354 // the queue may not be empty.
5355 }
5356 };
5357
5358 // Driver routine for parallel reference processing.
5359 // Creates an instance of the ref processing gang
5360 // task and has the worker threads execute it.
5361 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5362 assert(_workers != NULL, "Need parallel worker threads.");
5363
5364 ParallelTaskTerminator terminator(_active_workers, _queues);
5365 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5366
5367 _workers->run_task(&proc_task_proxy);
5368 }
5369
5370 // Gang task for parallel reference enqueueing.
5371
5372 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5373 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5374 EnqueueTask& _enq_task;
5375
5376 public:
5377 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5378 AbstractGangTask("Enqueue reference objects in parallel"),
5379 _enq_task(enq_task)
5380 { }
5381
5382 virtual void work(uint worker_id) {
5383 _enq_task.work(worker_id);
5384 }
5385 };
5386
5387 // Driver routine for parallel reference enqueueing.
5388 // Creates an instance of the ref enqueueing gang
5389 // task and has the worker threads execute it.
5390
5391 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5392 assert(_workers != NULL, "Need parallel worker threads.");
5393
5394 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5395
5396 _workers->run_task(&enq_task_proxy);
5397 }
5398
5399 // End of weak reference support closures
5400
5401 // Abstract task used to preserve (i.e. copy) any referent objects
5402 // that are in the collection set and are pointed to by reference
5403 // objects discovered by the CM ref processor.
5404
5405 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5406 protected:
5407 G1CollectedHeap* _g1h;
5408 G1ParScanThreadStateSet* _pss;
5409 RefToScanQueueSet* _queues;
5410 ParallelTaskTerminator _terminator;
5411 uint _n_workers;
5412
5413 public:
5414 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5415 AbstractGangTask("ParPreserveCMReferents"),
5416 _g1h(g1h),
5417 _pss(per_thread_states),
5418 _queues(task_queues),
5419 _terminator(workers, _queues),
5420 _n_workers(workers)
5421 { }
5422
5423 void work(uint worker_id) {
5424 ResourceMark rm;
5425 HandleMark hm;
5426
5427 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5428 pss->set_ref_processor(NULL);
5429 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5430
5431 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5432
5433 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5434
5435 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5436
5437 if (_g1h->collector_state()->during_initial_mark_pause()) {
5438 // We also need to mark copied objects.
5439 copy_non_heap_cl = ©_mark_non_heap_cl;
5440 }
5441
5442 // Is alive closure
5443 G1AlwaysAliveClosure always_alive(_g1h);
5444
5445 // Copying keep alive closure. Applied to referent objects that need
5446 // to be copied.
5447 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5448
5449 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5450
5451 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5452 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5453
5454 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5455 // So this must be true - but assert just in case someone decides to
5456 // change the worker ids.
5457 assert(worker_id < limit, "sanity");
5458 assert(!rp->discovery_is_atomic(), "check this code");
5459
5460 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5461 for (uint idx = worker_id; idx < limit; idx += stride) {
5462 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5463
5464 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5465 while (iter.has_next()) {
5466 // Since discovery is not atomic for the CM ref processor, we
5467 // can see some null referent objects.
5468 iter.load_ptrs(DEBUG_ONLY(true));
5469 oop ref = iter.obj();
5470
5471 // This will filter nulls.
5472 if (iter.is_referent_alive()) {
5473 iter.make_referent_alive();
5474 }
5475 iter.move_to_next();
5476 }
5477 }
5478
5479 // Drain the queue - which may cause stealing
5480 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5481 drain_queue.do_void();
5482 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5483 assert(pss->queue_is_empty(), "should be");
5484 }
5485 };
5486
5487 // Weak Reference processing during an evacuation pause (part 1).
5488 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5489 double ref_proc_start = os::elapsedTime();
5490
5491 ReferenceProcessor* rp = _ref_processor_stw;
5492 assert(rp->discovery_enabled(), "should have been enabled");
5493
5494 // Any reference objects, in the collection set, that were 'discovered'
5495 // by the CM ref processor should have already been copied (either by
5496 // applying the external root copy closure to the discovered lists, or
5497 // by following an RSet entry).
5498 //
5499 // But some of the referents, that are in the collection set, that these
5500 // reference objects point to may not have been copied: the STW ref
5501 // processor would have seen that the reference object had already
5502 // been 'discovered' and would have skipped discovering the reference,
5503 // but would not have treated the reference object as a regular oop.
5504 // As a result the copy closure would not have been applied to the
5505 // referent object.
5506 //
5507 // We need to explicitly copy these referent objects - the references
5508 // will be processed at the end of remarking.
5509 //
5510 // We also need to do this copying before we process the reference
5511 // objects discovered by the STW ref processor in case one of these
5512 // referents points to another object which is also referenced by an
5513 // object discovered by the STW ref processor.
5514
5515 uint no_of_gc_workers = workers()->active_workers();
5516
5517 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5518 per_thread_states,
5519 no_of_gc_workers,
5520 _task_queues);
5521
5522 workers()->run_task(&keep_cm_referents);
5523
5524 // Closure to test whether a referent is alive.
5525 G1STWIsAliveClosure is_alive(this);
5526
5527 // Even when parallel reference processing is enabled, the processing
5528 // of JNI refs is serial and performed serially by the current thread
5529 // rather than by a worker. The following PSS will be used for processing
5530 // JNI refs.
5531
5532 // Use only a single queue for this PSS.
5533 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5534 pss->set_ref_processor(NULL);
5535 assert(pss->queue_is_empty(), "pre-condition");
5536
5537 // We do not embed a reference processor in the copying/scanning
5538 // closures while we're actually processing the discovered
5539 // reference objects.
5540
5541 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss);
5542
5543 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5544
5545 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5546
5547 if (collector_state()->during_initial_mark_pause()) {
5548 // We also need to mark copied objects.
5549 copy_non_heap_cl = ©_mark_non_heap_cl;
5550 }
5551
5552 // Keep alive closure.
5553 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5554
5555 // Serial Complete GC closure
5556 G1STWDrainQueueClosure drain_queue(this, pss);
5557
5558 // Setup the soft refs policy...
5559 rp->setup_policy(false);
5560
5561 ReferenceProcessorStats stats;
5562 if (!rp->processing_is_mt()) {
5563 // Serial reference processing...
5564 stats = rp->process_discovered_references(&is_alive,
5565 &keep_alive,
5566 &drain_queue,
5567 NULL,
5568 _gc_timer_stw,
5569 _gc_tracer_stw->gc_id());
5570 } else {
5571 // Parallel reference processing
5572 assert(rp->num_q() == no_of_gc_workers, "sanity");
5573 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5574
5575 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5576 stats = rp->process_discovered_references(&is_alive,
5577 &keep_alive,
5578 &drain_queue,
5579 &par_task_executor,
5580 _gc_timer_stw,
5581 _gc_tracer_stw->gc_id());
5582 }
5583
5584 _gc_tracer_stw->report_gc_reference_stats(stats);
5585
5586 // We have completed copying any necessary live referent objects.
5587 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5588
5589 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5590 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5591 }
5592
5593 // Weak Reference processing during an evacuation pause (part 2).
5594 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5595 double ref_enq_start = os::elapsedTime();
5596
5597 ReferenceProcessor* rp = _ref_processor_stw;
5598 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5599
5600 // Now enqueue any remaining on the discovered lists on to
5601 // the pending list.
5602 if (!rp->processing_is_mt()) {
5603 // Serial reference processing...
5604 rp->enqueue_discovered_references();
5605 } else {
5606 // Parallel reference enqueueing
5607
5608 uint n_workers = workers()->active_workers();
5609
5610 assert(rp->num_q() == n_workers, "sanity");
5611 assert(n_workers <= rp->max_num_q(), "sanity");
5612
5613 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5614 rp->enqueue_discovered_references(&par_task_executor);
5615 }
5616
5617 rp->verify_no_references_recorded();
5618 assert(!rp->discovery_enabled(), "should have been disabled");
5619
5620 // FIXME
5621 // CM's reference processing also cleans up the string and symbol tables.
5622 // Should we do that here also? We could, but it is a serial operation
5623 // and could significantly increase the pause time.
5624
5625 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5626 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5627 }
5628
5629 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5630 _expand_heap_after_alloc_failure = true;
5631 _evacuation_failed = false;
5632
5633 // Should G1EvacuationFailureALot be in effect for this GC?
5634 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5635
5636 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5637
5638 // Disable the hot card cache.
5639 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5640 hot_card_cache->reset_hot_cache_claimed_index();
5641 hot_card_cache->set_use_cache(false);
5642
5643 const uint n_workers = workers()->active_workers();
5644
5645 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5646 double start_par_time_sec = os::elapsedTime();
5647 double end_par_time_sec;
5648
5649 {
5650 G1RootProcessor root_processor(this, n_workers);
5651 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5652 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5653 if (collector_state()->during_initial_mark_pause()) {
5654 ClassLoaderDataGraph::clear_claimed_marks();
5655 }
5656
5657 // The individual threads will set their evac-failure closures.
5658 if (PrintTerminationStats) {
5659 print_termination_stats_hdr(gclog_or_tty);
5660 }
5661
5662 workers()->run_task(&g1_par_task);
5663 end_par_time_sec = os::elapsedTime();
5664
5665 // Closing the inner scope will execute the destructor
5666 // for the G1RootProcessor object. We record the current
5667 // elapsed time before closing the scope so that time
5668 // taken for the destructor is NOT included in the
5669 // reported parallel time.
5670 }
5671
5672 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5673
5674 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5675 phase_times->record_par_time(par_time_ms);
5676
5677 double code_root_fixup_time_ms =
5678 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5679 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5680
5681 // Process any discovered reference objects - we have
5682 // to do this _before_ we retire the GC alloc regions
5683 // as we may have to copy some 'reachable' referent
5684 // objects (and their reachable sub-graphs) that were
5685 // not copied during the pause.
5686 process_discovered_references(per_thread_states);
5687
5688 if (G1StringDedup::is_enabled()) {
5689 double fixup_start = os::elapsedTime();
5690
5691 G1STWIsAliveClosure is_alive(this);
5692 G1KeepAliveClosure keep_alive(this);
5693 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5694
5695 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5696 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5697 }
5698
5699 _allocator->release_gc_alloc_regions(evacuation_info);
5700 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5701
5702 per_thread_states->flush();
5703
5704 record_obj_copy_mem_stats();
5705
5706 // Reset and re-enable the hot card cache.
5707 // Note the counts for the cards in the regions in the
5708 // collection set are reset when the collection set is freed.
5709 hot_card_cache->reset_hot_cache();
5710 hot_card_cache->set_use_cache(true);
5711
5712 purge_code_root_memory();
5713
5714 if (evacuation_failed()) {
5715 remove_self_forwarding_pointers();
5716
5717 // Reset the G1EvacuationFailureALot counters and flags
5718 // Note: the values are reset only when an actual
5719 // evacuation failure occurs.
5720 NOT_PRODUCT(reset_evacuation_should_fail();)
5721 }
5722
5723 // Enqueue any remaining references remaining on the STW
5724 // reference processor's discovered lists. We need to do
5725 // this after the card table is cleaned (and verified) as
5726 // the act of enqueueing entries on to the pending list
5727 // will log these updates (and dirty their associated
5728 // cards). We need these updates logged to update any
5729 // RSets.
5730 enqueue_discovered_references(per_thread_states);
5731
5732 redirty_logged_cards();
5733 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5734 }
5735
5736 void G1CollectedHeap::record_obj_copy_mem_stats() {
5737 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5738 create_g1_evac_summary(&_old_evac_stats));
5739 }
5740
5741 void G1CollectedHeap::free_region(HeapRegion* hr,
5742 FreeRegionList* free_list,
5743 bool par,
5744 bool locked) {
5745 assert(!hr->is_free(), "the region should not be free");
5746 assert(!hr->is_empty(), "the region should not be empty");
5747 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5748 assert(free_list != NULL, "pre-condition");
5749
5750 if (G1VerifyBitmaps) {
5751 MemRegion mr(hr->bottom(), hr->end());
5752 concurrent_mark()->clearRangePrevBitmap(mr);
5753 }
5754
5755 // Clear the card counts for this region.
5756 // Note: we only need to do this if the region is not young
5757 // (since we don't refine cards in young regions).
5758 if (!hr->is_young()) {
5759 _cg1r->hot_card_cache()->reset_card_counts(hr);
5760 }
5761 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5762 free_list->add_ordered(hr);
5763 }
5764
5765 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5766 FreeRegionList* free_list,
5767 bool par) {
5768 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5769 assert(free_list != NULL, "pre-condition");
5770
5771 size_t hr_capacity = hr->capacity();
5772 // We need to read this before we make the region non-humongous,
5773 // otherwise the information will be gone.
5774 uint last_index = hr->last_hc_index();
5775 hr->clear_humongous();
5776 free_region(hr, free_list, par);
5777
5778 uint i = hr->hrm_index() + 1;
5779 while (i < last_index) {
5780 HeapRegion* curr_hr = region_at(i);
5781 assert(curr_hr->is_continues_humongous(), "invariant");
5782 curr_hr->clear_humongous();
5783 free_region(curr_hr, free_list, par);
5784 i += 1;
5785 }
5786 }
5787
5788 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5789 const HeapRegionSetCount& humongous_regions_removed) {
5790 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5791 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5792 _old_set.bulk_remove(old_regions_removed);
5793 _humongous_set.bulk_remove(humongous_regions_removed);
5794 }
5795
5796 }
5797
5798 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5799 assert(list != NULL, "list can't be null");
5800 if (!list->is_empty()) {
5801 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5802 _hrm.insert_list_into_free_list(list);
5803 }
5804 }
5805
5806 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5807 decrease_used(bytes);
5808 }
5809
5810 class G1ParCleanupCTTask : public AbstractGangTask {
5811 G1SATBCardTableModRefBS* _ct_bs;
5812 G1CollectedHeap* _g1h;
5813 HeapRegion* volatile _su_head;
5814 public:
5815 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5816 G1CollectedHeap* g1h) :
5817 AbstractGangTask("G1 Par Cleanup CT Task"),
5818 _ct_bs(ct_bs), _g1h(g1h) { }
5819
5820 void work(uint worker_id) {
5821 HeapRegion* r;
5822 while (r = _g1h->pop_dirty_cards_region()) {
5823 clear_cards(r);
5824 }
5825 }
5826
5827 void clear_cards(HeapRegion* r) {
5828 // Cards of the survivors should have already been dirtied.
5829 if (!r->is_survivor()) {
5830 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5831 }
5832 }
5833 };
5834
5835 #ifndef PRODUCT
5836 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5837 G1CollectedHeap* _g1h;
5838 G1SATBCardTableModRefBS* _ct_bs;
5839 public:
5840 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5841 : _g1h(g1h), _ct_bs(ct_bs) { }
5842 virtual bool doHeapRegion(HeapRegion* r) {
5843 if (r->is_survivor()) {
5844 _g1h->verify_dirty_region(r);
5845 } else {
5846 _g1h->verify_not_dirty_region(r);
5847 }
5848 return false;
5849 }
5850 };
5851
5852 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5853 // All of the region should be clean.
5854 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5855 MemRegion mr(hr->bottom(), hr->end());
5856 ct_bs->verify_not_dirty_region(mr);
5857 }
5858
5859 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5860 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5861 // dirty allocated blocks as they allocate them. The thread that
5862 // retires each region and replaces it with a new one will do a
5863 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5864 // not dirty that area (one less thing to have to do while holding
5865 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5866 // is dirty.
5867 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5868 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5869 if (hr->is_young()) {
5870 ct_bs->verify_g1_young_region(mr);
5871 } else {
5872 ct_bs->verify_dirty_region(mr);
5873 }
5874 }
5875
5876 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5877 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5878 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5879 verify_dirty_region(hr);
5880 }
5881 }
5882
5883 void G1CollectedHeap::verify_dirty_young_regions() {
5884 verify_dirty_young_list(_young_list->first_region());
5885 }
5886
5887 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5888 HeapWord* tams, HeapWord* end) {
5889 guarantee(tams <= end,
5890 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5891 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5892 if (result < end) {
5893 gclog_or_tty->cr();
5894 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5895 bitmap_name, p2i(result));
5896 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5897 bitmap_name, p2i(tams), p2i(end));
5898 return false;
5899 }
5900 return true;
5901 }
5902
5903 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5904 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5905 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5906
5907 HeapWord* bottom = hr->bottom();
5908 HeapWord* ptams = hr->prev_top_at_mark_start();
5909 HeapWord* ntams = hr->next_top_at_mark_start();
5910 HeapWord* end = hr->end();
5911
5912 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5913
5914 bool res_n = true;
5915 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5916 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5917 // if we happen to be in that state.
5918 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5919 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5920 }
5921 if (!res_p || !res_n) {
5922 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5923 HR_FORMAT_PARAMS(hr));
5924 gclog_or_tty->print_cr("#### Caller: %s", caller);
5925 return false;
5926 }
5927 return true;
5928 }
5929
5930 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5931 if (!G1VerifyBitmaps) return;
5932
5933 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5934 }
5935
5936 class G1VerifyBitmapClosure : public HeapRegionClosure {
5937 private:
5938 const char* _caller;
5939 G1CollectedHeap* _g1h;
5940 bool _failures;
5941
5942 public:
5943 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5944 _caller(caller), _g1h(g1h), _failures(false) { }
5945
5946 bool failures() { return _failures; }
5947
5948 virtual bool doHeapRegion(HeapRegion* hr) {
5949 if (hr->is_continues_humongous()) return false;
5950
5951 bool result = _g1h->verify_bitmaps(_caller, hr);
5952 if (!result) {
5953 _failures = true;
5954 }
5955 return false;
5956 }
5957 };
5958
5959 void G1CollectedHeap::check_bitmaps(const char* caller) {
5960 if (!G1VerifyBitmaps) return;
5961
5962 G1VerifyBitmapClosure cl(caller, this);
5963 heap_region_iterate(&cl);
5964 guarantee(!cl.failures(), "bitmap verification");
5965 }
5966
5967 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5968 private:
5969 bool _failures;
5970 public:
5971 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5972
5973 virtual bool doHeapRegion(HeapRegion* hr) {
5974 uint i = hr->hrm_index();
5975 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5976 if (hr->is_humongous()) {
5977 if (hr->in_collection_set()) {
5978 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5979 _failures = true;
5980 return true;
5981 }
5982 if (cset_state.is_in_cset()) {
5983 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5984 _failures = true;
5985 return true;
5986 }
5987 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5988 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5989 _failures = true;
5990 return true;
5991 }
5992 } else {
5993 if (cset_state.is_humongous()) {
5994 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5995 _failures = true;
5996 return true;
5997 }
5998 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5999 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6000 hr->in_collection_set(), cset_state.value(), i);
6001 _failures = true;
6002 return true;
6003 }
6004 if (cset_state.is_in_cset()) {
6005 if (hr->is_young() != (cset_state.is_young())) {
6006 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6007 hr->is_young(), cset_state.value(), i);
6008 _failures = true;
6009 return true;
6010 }
6011 if (hr->is_old() != (cset_state.is_old())) {
6012 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6013 hr->is_old(), cset_state.value(), i);
6014 _failures = true;
6015 return true;
6016 }
6017 }
6018 }
6019 return false;
6020 }
6021
6022 bool failures() const { return _failures; }
6023 };
6024
6025 bool G1CollectedHeap::check_cset_fast_test() {
6026 G1CheckCSetFastTableClosure cl;
6027 _hrm.iterate(&cl);
6028 return !cl.failures();
6029 }
6030 #endif // PRODUCT
6031
6032 void G1CollectedHeap::cleanUpCardTable() {
6033 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6034 double start = os::elapsedTime();
6035
6036 {
6037 // Iterate over the dirty cards region list.
6038 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6039
6040 workers()->run_task(&cleanup_task);
6041 #ifndef PRODUCT
6042 if (G1VerifyCTCleanup || VerifyAfterGC) {
6043 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6044 heap_region_iterate(&cleanup_verifier);
6045 }
6046 #endif
6047 }
6048
6049 double elapsed = os::elapsedTime() - start;
6050 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6051 }
6052
6053 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6054 size_t pre_used = 0;
6055 FreeRegionList local_free_list("Local List for CSet Freeing");
6056
6057 double young_time_ms = 0.0;
6058 double non_young_time_ms = 0.0;
6059
6060 // Since the collection set is a superset of the the young list,
6061 // all we need to do to clear the young list is clear its
6062 // head and length, and unlink any young regions in the code below
6063 _young_list->clear();
6064
6065 G1CollectorPolicy* policy = g1_policy();
6066
6067 double start_sec = os::elapsedTime();
6068 bool non_young = true;
6069
6070 HeapRegion* cur = cs_head;
6071 int age_bound = -1;
6072 size_t rs_lengths = 0;
6073
6074 while (cur != NULL) {
6075 assert(!is_on_master_free_list(cur), "sanity");
6076 if (non_young) {
6077 if (cur->is_young()) {
6078 double end_sec = os::elapsedTime();
6079 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6080 non_young_time_ms += elapsed_ms;
6081
6082 start_sec = os::elapsedTime();
6083 non_young = false;
6084 }
6085 } else {
6086 if (!cur->is_young()) {
6087 double end_sec = os::elapsedTime();
6088 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6089 young_time_ms += elapsed_ms;
6090
6091 start_sec = os::elapsedTime();
6092 non_young = true;
6093 }
6094 }
6095
6096 rs_lengths += cur->rem_set()->occupied_locked();
6097
6098 HeapRegion* next = cur->next_in_collection_set();
6099 assert(cur->in_collection_set(), "bad CS");
6100 cur->set_next_in_collection_set(NULL);
6101 clear_in_cset(cur);
6102
6103 if (cur->is_young()) {
6104 int index = cur->young_index_in_cset();
6105 assert(index != -1, "invariant");
6106 assert((uint) index < policy->young_cset_region_length(), "invariant");
6107 size_t words_survived = _surviving_young_words[index];
6108 cur->record_surv_words_in_group(words_survived);
6109
6110 // At this point the we have 'popped' cur from the collection set
6111 // (linked via next_in_collection_set()) but it is still in the
6112 // young list (linked via next_young_region()). Clear the
6113 // _next_young_region field.
6114 cur->set_next_young_region(NULL);
6115 } else {
6116 int index = cur->young_index_in_cset();
6117 assert(index == -1, "invariant");
6118 }
6119
6120 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6121 (!cur->is_young() && cur->young_index_in_cset() == -1),
6122 "invariant" );
6123
6124 if (!cur->evacuation_failed()) {
6125 MemRegion used_mr = cur->used_region();
6126
6127 // And the region is empty.
6128 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6129 pre_used += cur->used();
6130 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6131 } else {
6132 cur->uninstall_surv_rate_group();
6133 if (cur->is_young()) {
6134 cur->set_young_index_in_cset(-1);
6135 }
6136 cur->set_evacuation_failed(false);
6137 // The region is now considered to be old.
6138 cur->set_old();
6139 // Do some allocation statistics accounting. Regions that failed evacuation
6140 // are always made old, so there is no need to update anything in the young
6141 // gen statistics, but we need to update old gen statistics.
6142 size_t used_words = cur->marked_bytes() / HeapWordSize;
6143 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6144 _old_set.add(cur);
6145 evacuation_info.increment_collectionset_used_after(cur->used());
6146 }
6147 cur = next;
6148 }
6149
6150 evacuation_info.set_regions_freed(local_free_list.length());
6151 policy->record_max_rs_lengths(rs_lengths);
6152 policy->cset_regions_freed();
6153
6154 double end_sec = os::elapsedTime();
6155 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6156
6157 if (non_young) {
6158 non_young_time_ms += elapsed_ms;
6159 } else {
6160 young_time_ms += elapsed_ms;
6161 }
6162
6163 prepend_to_freelist(&local_free_list);
6164 decrement_summary_bytes(pre_used);
6165 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6166 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6167 }
6168
6169 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6170 private:
6171 FreeRegionList* _free_region_list;
6172 HeapRegionSet* _proxy_set;
6173 HeapRegionSetCount _humongous_regions_removed;
6174 size_t _freed_bytes;
6175 public:
6176
6177 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6178 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6179 }
6180
6181 virtual bool doHeapRegion(HeapRegion* r) {
6182 if (!r->is_starts_humongous()) {
6183 return false;
6184 }
6185
6186 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6187
6188 oop obj = (oop)r->bottom();
6189 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6190
6191 // The following checks whether the humongous object is live are sufficient.
6192 // The main additional check (in addition to having a reference from the roots
6193 // or the young gen) is whether the humongous object has a remembered set entry.
6194 //
6195 // A humongous object cannot be live if there is no remembered set for it
6196 // because:
6197 // - there can be no references from within humongous starts regions referencing
6198 // the object because we never allocate other objects into them.
6199 // (I.e. there are no intra-region references that may be missed by the
6200 // remembered set)
6201 // - as soon there is a remembered set entry to the humongous starts region
6202 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6203 // until the end of a concurrent mark.
6204 //
6205 // It is not required to check whether the object has been found dead by marking
6206 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6207 // all objects allocated during that time are considered live.
6208 // SATB marking is even more conservative than the remembered set.
6209 // So if at this point in the collection there is no remembered set entry,
6210 // nobody has a reference to it.
6211 // At the start of collection we flush all refinement logs, and remembered sets
6212 // are completely up-to-date wrt to references to the humongous object.
6213 //
6214 // Other implementation considerations:
6215 // - never consider object arrays at this time because they would pose
6216 // considerable effort for cleaning up the the remembered sets. This is
6217 // required because stale remembered sets might reference locations that
6218 // are currently allocated into.
6219 uint region_idx = r->hrm_index();
6220 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6221 !r->rem_set()->is_empty()) {
6222
6223 if (G1TraceEagerReclaimHumongousObjects) {
6224 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",
6225 region_idx,
6226 (size_t)obj->size() * HeapWordSize,
6227 p2i(r->bottom()),
6228 r->region_num(),
6229 r->rem_set()->occupied(),
6230 r->rem_set()->strong_code_roots_list_length(),
6231 next_bitmap->isMarked(r->bottom()),
6232 g1h->is_humongous_reclaim_candidate(region_idx),
6233 obj->is_typeArray()
6234 );
6235 }
6236
6237 return false;
6238 }
6239
6240 guarantee(obj->is_typeArray(),
6241 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6242 PTR_FORMAT " is not.",
6243 p2i(r->bottom())));
6244
6245 if (G1TraceEagerReclaimHumongousObjects) {
6246 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",
6247 region_idx,
6248 (size_t)obj->size() * HeapWordSize,
6249 p2i(r->bottom()),
6250 r->region_num(),
6251 r->rem_set()->occupied(),
6252 r->rem_set()->strong_code_roots_list_length(),
6253 next_bitmap->isMarked(r->bottom()),
6254 g1h->is_humongous_reclaim_candidate(region_idx),
6255 obj->is_typeArray()
6256 );
6257 }
6258 // Need to clear mark bit of the humongous object if already set.
6259 if (next_bitmap->isMarked(r->bottom())) {
6260 next_bitmap->clear(r->bottom());
6261 }
6262 _freed_bytes += r->used();
6263 r->set_containing_set(NULL);
6264 _humongous_regions_removed.increment(1u, r->capacity());
6265 g1h->free_humongous_region(r, _free_region_list, false);
6266
6267 return false;
6268 }
6269
6270 HeapRegionSetCount& humongous_free_count() {
6271 return _humongous_regions_removed;
6272 }
6273
6274 size_t bytes_freed() const {
6275 return _freed_bytes;
6276 }
6277
6278 size_t humongous_reclaimed() const {
6279 return _humongous_regions_removed.length();
6280 }
6281 };
6282
6283 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6284 assert_at_safepoint(true);
6285
6286 if (!G1EagerReclaimHumongousObjects ||
6287 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6288 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6289 return;
6290 }
6291
6292 double start_time = os::elapsedTime();
6293
6294 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6295
6296 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6297 heap_region_iterate(&cl);
6298
6299 HeapRegionSetCount empty_set;
6300 remove_from_old_sets(empty_set, cl.humongous_free_count());
6301
6302 G1HRPrinter* hrp = hr_printer();
6303 if (hrp->is_active()) {
6304 FreeRegionListIterator iter(&local_cleanup_list);
6305 while (iter.more_available()) {
6306 HeapRegion* hr = iter.get_next();
6307 hrp->cleanup(hr);
6308 }
6309 }
6310
6311 prepend_to_freelist(&local_cleanup_list);
6312 decrement_summary_bytes(cl.bytes_freed());
6313
6314 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6315 cl.humongous_reclaimed());
6316 }
6317
6318 // This routine is similar to the above but does not record
6319 // any policy statistics or update free lists; we are abandoning
6320 // the current incremental collection set in preparation of a
6321 // full collection. After the full GC we will start to build up
6322 // the incremental collection set again.
6323 // This is only called when we're doing a full collection
6324 // and is immediately followed by the tearing down of the young list.
6325
6326 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6327 HeapRegion* cur = cs_head;
6328
6329 while (cur != NULL) {
6330 HeapRegion* next = cur->next_in_collection_set();
6331 assert(cur->in_collection_set(), "bad CS");
6332 cur->set_next_in_collection_set(NULL);
6333 clear_in_cset(cur);
6334 cur->set_young_index_in_cset(-1);
6335 cur = next;
6336 }
6337 }
6338
6339 void G1CollectedHeap::set_free_regions_coming() {
6340 if (G1ConcRegionFreeingVerbose) {
6341 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6342 "setting free regions coming");
6343 }
6344
6345 assert(!free_regions_coming(), "pre-condition");
6346 _free_regions_coming = true;
6347 }
6348
6349 void G1CollectedHeap::reset_free_regions_coming() {
6350 assert(free_regions_coming(), "pre-condition");
6351
6352 {
6353 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6354 _free_regions_coming = false;
6355 SecondaryFreeList_lock->notify_all();
6356 }
6357
6358 if (G1ConcRegionFreeingVerbose) {
6359 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6360 "reset free regions coming");
6361 }
6362 }
6363
6364 void G1CollectedHeap::wait_while_free_regions_coming() {
6365 // Most of the time we won't have to wait, so let's do a quick test
6366 // first before we take the lock.
6367 if (!free_regions_coming()) {
6368 return;
6369 }
6370
6371 if (G1ConcRegionFreeingVerbose) {
6372 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6373 "waiting for free regions");
6374 }
6375
6376 {
6377 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6378 while (free_regions_coming()) {
6379 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6380 }
6381 }
6382
6383 if (G1ConcRegionFreeingVerbose) {
6384 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6385 "done waiting for free regions");
6386 }
6387 }
6388
6389 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6390 return _allocator->is_retained_old_region(hr);
6391 }
6392
6393 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6394 _young_list->push_region(hr);
6395 }
6396
6397 class NoYoungRegionsClosure: public HeapRegionClosure {
6398 private:
6399 bool _success;
6400 public:
6401 NoYoungRegionsClosure() : _success(true) { }
6402 bool doHeapRegion(HeapRegion* r) {
6403 if (r->is_young()) {
6404 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6405 p2i(r->bottom()), p2i(r->end()));
6406 _success = false;
6407 }
6408 return false;
6409 }
6410 bool success() { return _success; }
6411 };
6412
6413 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6414 bool ret = _young_list->check_list_empty(check_sample);
6415
6416 if (check_heap) {
6417 NoYoungRegionsClosure closure;
6418 heap_region_iterate(&closure);
6419 ret = ret && closure.success();
6420 }
6421
6422 return ret;
6423 }
6424
6425 class TearDownRegionSetsClosure : public HeapRegionClosure {
6426 private:
6427 HeapRegionSet *_old_set;
6428
6429 public:
6430 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6431
6432 bool doHeapRegion(HeapRegion* r) {
6433 if (r->is_old()) {
6434 _old_set->remove(r);
6435 } else {
6436 // We ignore free regions, we'll empty the free list afterwards.
6437 // We ignore young regions, we'll empty the young list afterwards.
6438 // We ignore humongous regions, we're not tearing down the
6439 // humongous regions set.
6440 assert(r->is_free() || r->is_young() || r->is_humongous(),
6441 "it cannot be another type");
6442 }
6443 return false;
6444 }
6445
6446 ~TearDownRegionSetsClosure() {
6447 assert(_old_set->is_empty(), "post-condition");
6448 }
6449 };
6450
6451 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6452 assert_at_safepoint(true /* should_be_vm_thread */);
6453
6454 if (!free_list_only) {
6455 TearDownRegionSetsClosure cl(&_old_set);
6456 heap_region_iterate(&cl);
6457
6458 // Note that emptying the _young_list is postponed and instead done as
6459 // the first step when rebuilding the regions sets again. The reason for
6460 // this is that during a full GC string deduplication needs to know if
6461 // a collected region was young or old when the full GC was initiated.
6462 }
6463 _hrm.remove_all_free_regions();
6464 }
6465
6466 void G1CollectedHeap::increase_used(size_t bytes) {
6467 _summary_bytes_used += bytes;
6468 }
6469
6470 void G1CollectedHeap::decrease_used(size_t bytes) {
6471 assert(_summary_bytes_used >= bytes,
6472 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6473 _summary_bytes_used, bytes));
6474 _summary_bytes_used -= bytes;
6475 }
6476
6477 void G1CollectedHeap::set_used(size_t bytes) {
6478 _summary_bytes_used = bytes;
6479 }
6480
6481 class RebuildRegionSetsClosure : public HeapRegionClosure {
6482 private:
6483 bool _free_list_only;
6484 HeapRegionSet* _old_set;
6485 HeapRegionManager* _hrm;
6486 size_t _total_used;
6487
6488 public:
6489 RebuildRegionSetsClosure(bool free_list_only,
6490 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6491 _free_list_only(free_list_only),
6492 _old_set(old_set), _hrm(hrm), _total_used(0) {
6493 assert(_hrm->num_free_regions() == 0, "pre-condition");
6494 if (!free_list_only) {
6495 assert(_old_set->is_empty(), "pre-condition");
6496 }
6497 }
6498
6499 bool doHeapRegion(HeapRegion* r) {
6500 if (r->is_continues_humongous()) {
6501 return false;
6502 }
6503
6504 if (r->is_empty()) {
6505 // Add free regions to the free list
6506 r->set_free();
6507 r->set_allocation_context(AllocationContext::system());
6508 _hrm->insert_into_free_list(r);
6509 } else if (!_free_list_only) {
6510 assert(!r->is_young(), "we should not come across young regions");
6511
6512 if (r->is_humongous()) {
6513 // We ignore humongous regions. We left the humongous set unchanged.
6514 } else {
6515 // Objects that were compacted would have ended up on regions
6516 // that were previously old or free. Archive regions (which are
6517 // old) will not have been touched.
6518 assert(r->is_free() || r->is_old(), "invariant");
6519 // We now consider them old, so register as such. Leave
6520 // archive regions set that way, however, while still adding
6521 // them to the old set.
6522 if (!r->is_archive()) {
6523 r->set_old();
6524 }
6525 _old_set->add(r);
6526 }
6527 _total_used += r->used();
6528 }
6529
6530 return false;
6531 }
6532
6533 size_t total_used() {
6534 return _total_used;
6535 }
6536 };
6537
6538 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6539 assert_at_safepoint(true /* should_be_vm_thread */);
6540
6541 if (!free_list_only) {
6542 _young_list->empty_list();
6543 }
6544
6545 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6546 heap_region_iterate(&cl);
6547
6548 if (!free_list_only) {
6549 set_used(cl.total_used());
6550 if (_archive_allocator != NULL) {
6551 _archive_allocator->clear_used();
6552 }
6553 }
6554 assert(used_unlocked() == recalculate_used(),
6555 err_msg("inconsistent used_unlocked(), "
6556 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6557 used_unlocked(), recalculate_used()));
6558 }
6559
6560 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6561 _refine_cte_cl->set_concurrent(concurrent);
6562 }
6563
6564 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6565 HeapRegion* hr = heap_region_containing(p);
6566 return hr->is_in(p);
6567 }
6568
6569 // Methods for the mutator alloc region
6570
6571 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6572 bool force) {
6573 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6574 assert(!force || g1_policy()->can_expand_young_list(),
6575 "if force is true we should be able to expand the young list");
6576 bool young_list_full = g1_policy()->is_young_list_full();
6577 if (force || !young_list_full) {
6578 HeapRegion* new_alloc_region = new_region(word_size,
6579 false /* is_old */,
6580 false /* do_expand */);
6581 if (new_alloc_region != NULL) {
6582 set_region_short_lived_locked(new_alloc_region);
6583 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6584 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6585 return new_alloc_region;
6586 }
6587 }
6588 return NULL;
6589 }
6590
6591 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6592 size_t allocated_bytes) {
6593 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6594 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6595
6596 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6597 increase_used(allocated_bytes);
6598 _hr_printer.retire(alloc_region);
6599 // We update the eden sizes here, when the region is retired,
6600 // instead of when it's allocated, since this is the point that its
6601 // used space has been recored in _summary_bytes_used.
6602 g1mm()->update_eden_size();
6603 }
6604
6605 // Methods for the GC alloc regions
6606
6607 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6608 uint count,
6609 InCSetState dest) {
6610 assert(FreeList_lock->owned_by_self(), "pre-condition");
6611
6612 if (count < g1_policy()->max_regions(dest)) {
6613 const bool is_survivor = (dest.is_young());
6614 HeapRegion* new_alloc_region = new_region(word_size,
6615 !is_survivor,
6616 true /* do_expand */);
6617 if (new_alloc_region != NULL) {
6618 // We really only need to do this for old regions given that we
6619 // should never scan survivors. But it doesn't hurt to do it
6620 // for survivors too.
6621 new_alloc_region->record_timestamp();
6622 if (is_survivor) {
6623 new_alloc_region->set_survivor();
6624 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6625 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6626 } else {
6627 new_alloc_region->set_old();
6628 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6629 check_bitmaps("Old Region Allocation", new_alloc_region);
6630 }
6631 bool during_im = collector_state()->during_initial_mark_pause();
6632 new_alloc_region->note_start_of_copying(during_im);
6633 return new_alloc_region;
6634 }
6635 }
6636 return NULL;
6637 }
6638
6639 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6640 size_t allocated_bytes,
6641 InCSetState dest) {
6642 bool during_im = collector_state()->during_initial_mark_pause();
6643 alloc_region->note_end_of_copying(during_im);
6644 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6645 if (dest.is_young()) {
6646 young_list()->add_survivor_region(alloc_region);
6647 } else {
6648 _old_set.add(alloc_region);
6649 }
6650 _hr_printer.retire(alloc_region);
6651 }
6652
6653 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6654 bool expanded = false;
6655 uint index = _hrm.find_highest_free(&expanded);
6656
6657 if (index != G1_NO_HRM_INDEX) {
6658 if (expanded) {
6659 ergo_verbose1(ErgoHeapSizing,
6660 "attempt heap expansion",
6661 ergo_format_reason("requested address range outside heap bounds")
6662 ergo_format_byte("region size"),
6663 HeapRegion::GrainWords * HeapWordSize);
6664 }
6665 _hrm.allocate_free_regions_starting_at(index, 1);
6666 return region_at(index);
6667 }
6668 return NULL;
6669 }
6670
6671 // Heap region set verification
6672
6673 class VerifyRegionListsClosure : public HeapRegionClosure {
6674 private:
6675 HeapRegionSet* _old_set;
6676 HeapRegionSet* _humongous_set;
6677 HeapRegionManager* _hrm;
6678
6679 public:
6680 HeapRegionSetCount _old_count;
6681 HeapRegionSetCount _humongous_count;
6682 HeapRegionSetCount _free_count;
6683
6684 VerifyRegionListsClosure(HeapRegionSet* old_set,
6685 HeapRegionSet* humongous_set,
6686 HeapRegionManager* hrm) :
6687 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6688 _old_count(), _humongous_count(), _free_count(){ }
6689
6690 bool doHeapRegion(HeapRegion* hr) {
6691 if (hr->is_continues_humongous()) {
6692 return false;
6693 }
6694
6695 if (hr->is_young()) {
6696 // TODO
6697 } else if (hr->is_starts_humongous()) {
6698 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6699 _humongous_count.increment(1u, hr->capacity());
6700 } else if (hr->is_empty()) {
6701 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6702 _free_count.increment(1u, hr->capacity());
6703 } else if (hr->is_old()) {
6704 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6705 _old_count.increment(1u, hr->capacity());
6706 } else {
6707 // There are no other valid region types. Check for one invalid
6708 // one we can identify: pinned without old or humongous set.
6709 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6710 ShouldNotReachHere();
6711 }
6712 return false;
6713 }
6714
6715 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6716 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6717 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6718 old_set->total_capacity_bytes(), _old_count.capacity()));
6719
6720 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6721 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6722 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6723
6724 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()));
6725 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6726 free_list->total_capacity_bytes(), _free_count.capacity()));
6727 }
6728 };
6729
6730 void G1CollectedHeap::verify_region_sets() {
6731 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6732
6733 // First, check the explicit lists.
6734 _hrm.verify();
6735 {
6736 // Given that a concurrent operation might be adding regions to
6737 // the secondary free list we have to take the lock before
6738 // verifying it.
6739 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6740 _secondary_free_list.verify_list();
6741 }
6742
6743 // If a concurrent region freeing operation is in progress it will
6744 // be difficult to correctly attributed any free regions we come
6745 // across to the correct free list given that they might belong to
6746 // one of several (free_list, secondary_free_list, any local lists,
6747 // etc.). So, if that's the case we will skip the rest of the
6748 // verification operation. Alternatively, waiting for the concurrent
6749 // operation to complete will have a non-trivial effect on the GC's
6750 // operation (no concurrent operation will last longer than the
6751 // interval between two calls to verification) and it might hide
6752 // any issues that we would like to catch during testing.
6753 if (free_regions_coming()) {
6754 return;
6755 }
6756
6757 // Make sure we append the secondary_free_list on the free_list so
6758 // that all free regions we will come across can be safely
6759 // attributed to the free_list.
6760 append_secondary_free_list_if_not_empty_with_lock();
6761
6762 // Finally, make sure that the region accounting in the lists is
6763 // consistent with what we see in the heap.
6764
6765 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6766 heap_region_iterate(&cl);
6767 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6768 }
6769
6770 // Optimized nmethod scanning
6771
6772 class RegisterNMethodOopClosure: public OopClosure {
6773 G1CollectedHeap* _g1h;
6774 nmethod* _nm;
6775
6776 template <class T> void do_oop_work(T* p) {
6777 T heap_oop = oopDesc::load_heap_oop(p);
6778 if (!oopDesc::is_null(heap_oop)) {
6779 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6780 HeapRegion* hr = _g1h->heap_region_containing(obj);
6781 assert(!hr->is_continues_humongous(),
6782 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6783 " starting at " HR_FORMAT,
6784 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6785
6786 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6787 hr->add_strong_code_root_locked(_nm);
6788 }
6789 }
6790
6791 public:
6792 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6793 _g1h(g1h), _nm(nm) {}
6794
6795 void do_oop(oop* p) { do_oop_work(p); }
6796 void do_oop(narrowOop* p) { do_oop_work(p); }
6797 };
6798
6799 class UnregisterNMethodOopClosure: public OopClosure {
6800 G1CollectedHeap* _g1h;
6801 nmethod* _nm;
6802
6803 template <class T> void do_oop_work(T* p) {
6804 T heap_oop = oopDesc::load_heap_oop(p);
6805 if (!oopDesc::is_null(heap_oop)) {
6806 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6807 HeapRegion* hr = _g1h->heap_region_containing(obj);
6808 assert(!hr->is_continues_humongous(),
6809 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6810 " starting at " HR_FORMAT,
6811 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6812
6813 hr->remove_strong_code_root(_nm);
6814 }
6815 }
6816
6817 public:
6818 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6819 _g1h(g1h), _nm(nm) {}
6820
6821 void do_oop(oop* p) { do_oop_work(p); }
6822 void do_oop(narrowOop* p) { do_oop_work(p); }
6823 };
6824
6825 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6826 CollectedHeap::register_nmethod(nm);
6827
6828 guarantee(nm != NULL, "sanity");
6829 RegisterNMethodOopClosure reg_cl(this, nm);
6830 nm->oops_do(®_cl);
6831 }
6832
6833 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6834 CollectedHeap::unregister_nmethod(nm);
6835
6836 guarantee(nm != NULL, "sanity");
6837 UnregisterNMethodOopClosure reg_cl(this, nm);
6838 nm->oops_do(®_cl, true);
6839 }
6840
6841 void G1CollectedHeap::purge_code_root_memory() {
6842 double purge_start = os::elapsedTime();
6843 G1CodeRootSet::purge();
6844 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6845 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6846 }
6847
6848 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6849 G1CollectedHeap* _g1h;
6850
6851 public:
6852 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6853 _g1h(g1h) {}
6854
6855 void do_code_blob(CodeBlob* cb) {
6856 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6857 if (nm == NULL) {
6858 return;
6859 }
6860
6861 if (ScavengeRootsInCode) {
6862 _g1h->register_nmethod(nm);
6863 }
6864 }
6865 };
6866
6867 void G1CollectedHeap::rebuild_strong_code_roots() {
6868 RebuildStrongCodeRootClosure blob_cl(this);
6869 CodeCache::blobs_do(&blob_cl);
6870 }