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/gcId.hpp"
57 #include "gc/shared/gcLocker.inline.hpp"
58 #include "gc/shared/gcTimer.hpp"
59 #include "gc/shared/gcTrace.hpp"
60 #include "gc/shared/gcTraceTime.hpp"
61 #include "gc/shared/generationSpec.hpp"
62 #include "gc/shared/isGCActiveMark.hpp"
63 #include "gc/shared/referenceProcessor.hpp"
64 #include "gc/shared/taskqueue.inline.hpp"
65 #include "memory/allocation.hpp"
66 #include "memory/iterator.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.inline.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
76
77 // turn it on so that the contents of the young list (scan-only /
78 // to-be-collected) are printed at "strategic" points before / during
79 // / after the collection --- this is useful for debugging
80 #define YOUNG_LIST_VERBOSE 0
81 // CURRENT STATUS
82 // This file is under construction. Search for "FIXME".
83
84 // INVARIANTS/NOTES
85 //
86 // All allocation activity covered by the G1CollectedHeap interface is
87 // serialized by acquiring the HeapLock. This happens in mem_allocate
88 // and allocate_new_tlab, which are the "entry" points to the
89 // allocation code from the rest of the JVM. (Note that this does not
90 // apply to TLAB allocation, which is not part of this interface: it
91 // is done by clients of this interface.)
92
93 // Local to this file.
94
95 class RefineCardTableEntryClosure: public CardTableEntryClosure {
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure() : _concurrent(true) { }
99
100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
102 // This path is executed by the concurrent refine or mutator threads,
103 // concurrently, and so we do not care if card_ptr contains references
104 // that point into the collection set.
105 assert(!oops_into_cset, "should be");
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
120 private:
121 size_t _num_processed;
122
123 public:
124 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
125
126 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 _num_processed++;
129 return true;
130 }
131
132 size_t num_processed() const { return _num_processed; }
133 };
134
135 YoungList::YoungList(G1CollectedHeap* g1h) :
136 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
138 guarantee(check_list_empty(false), "just making sure...");
139 }
140
141 void YoungList::push_region(HeapRegion *hr) {
142 assert(!hr->is_young(), "should not already be young");
143 assert(hr->get_next_young_region() == NULL, "cause it should!");
144
145 hr->set_next_young_region(_head);
146 _head = hr;
147
148 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
149 ++_length;
150 }
151
152 void YoungList::add_survivor_region(HeapRegion* hr) {
153 assert(hr->is_survivor(), "should be flagged as survivor region");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_survivor_head);
157 if (_survivor_head == NULL) {
158 _survivor_tail = hr;
159 }
160 _survivor_head = hr;
161 ++_survivor_length;
162 }
163
164 void YoungList::empty_list(HeapRegion* list) {
165 while (list != NULL) {
166 HeapRegion* next = list->get_next_young_region();
167 list->set_next_young_region(NULL);
168 list->uninstall_surv_rate_group();
169 // This is called before a Full GC and all the non-empty /
170 // non-humongous regions at the end of the Full GC will end up as
171 // old anyway.
172 list->set_old();
173 list = next;
174 }
175 }
176
177 void YoungList::empty_list() {
178 assert(check_list_well_formed(), "young list should be well formed");
179
180 empty_list(_head);
181 _head = NULL;
182 _length = 0;
183
184 empty_list(_survivor_head);
185 _survivor_head = NULL;
186 _survivor_tail = NULL;
187 _survivor_length = 0;
188
189 _last_sampled_rs_lengths = 0;
190
191 assert(check_list_empty(false), "just making sure...");
192 }
193
194 bool YoungList::check_list_well_formed() {
195 bool ret = true;
196
197 uint length = 0;
198 HeapRegion* curr = _head;
199 HeapRegion* last = NULL;
200 while (curr != NULL) {
201 if (!curr->is_young()) {
202 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
203 "incorrectly tagged (y: %d, surv: %d)",
204 p2i(curr->bottom()), p2i(curr->end()),
205 curr->is_young(), curr->is_survivor());
206 ret = false;
207 }
208 ++length;
209 last = curr;
210 curr = curr->get_next_young_region();
211 }
212 ret = ret && (length == _length);
213
214 if (!ret) {
215 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
216 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
217 length, _length);
218 }
219
220 return ret;
221 }
222
223 bool YoungList::check_list_empty(bool check_sample) {
224 bool ret = true;
225
226 if (_length != 0) {
227 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
228 _length);
229 ret = false;
230 }
231 if (check_sample && _last_sampled_rs_lengths != 0) {
232 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
233 ret = false;
234 }
235 if (_head != NULL) {
236 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
237 ret = false;
238 }
239 if (!ret) {
240 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
241 }
242
243 return ret;
244 }
245
246 void
247 YoungList::rs_length_sampling_init() {
248 _sampled_rs_lengths = 0;
249 _curr = _head;
250 }
251
252 bool
253 YoungList::rs_length_sampling_more() {
254 return _curr != NULL;
255 }
256
257 void
258 YoungList::rs_length_sampling_next() {
259 assert( _curr != NULL, "invariant" );
260 size_t rs_length = _curr->rem_set()->occupied();
261
262 _sampled_rs_lengths += rs_length;
263
264 // The current region may not yet have been added to the
265 // incremental collection set (it gets added when it is
266 // retired as the current allocation region).
267 if (_curr->in_collection_set()) {
268 // Update the collection set policy information for this region
269 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
270 }
271
272 _curr = _curr->get_next_young_region();
273 if (_curr == NULL) {
274 _last_sampled_rs_lengths = _sampled_rs_lengths;
275 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
276 }
277 }
278
279 void
280 YoungList::reset_auxilary_lists() {
281 guarantee( is_empty(), "young list should be empty" );
282 assert(check_list_well_formed(), "young list should be well formed");
283
284 // Add survivor regions to SurvRateGroup.
285 _g1h->g1_policy()->note_start_adding_survivor_regions();
286 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
287
288 int young_index_in_cset = 0;
289 for (HeapRegion* curr = _survivor_head;
290 curr != NULL;
291 curr = curr->get_next_young_region()) {
292 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
293
294 // The region is a non-empty survivor so let's add it to
295 // the incremental collection set for the next evacuation
296 // pause.
297 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
298 young_index_in_cset += 1;
299 }
300 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
301 _g1h->g1_policy()->note_stop_adding_survivor_regions();
302
303 _head = _survivor_head;
304 _length = _survivor_length;
305 if (_survivor_head != NULL) {
306 assert(_survivor_tail != NULL, "cause it shouldn't be");
307 assert(_survivor_length > 0, "invariant");
308 _survivor_tail->set_next_young_region(NULL);
309 }
310
311 // Don't clear the survivor list handles until the start of
312 // the next evacuation pause - we need it in order to re-tag
313 // the survivor regions from this evacuation pause as 'young'
314 // at the start of the next.
315
316 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
317
318 assert(check_list_well_formed(), "young list should be well formed");
319 }
320
321 void YoungList::print() {
322 HeapRegion* lists[] = {_head, _survivor_head};
323 const char* names[] = {"YOUNG", "SURVIVOR"};
324
325 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
326 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
327 HeapRegion *curr = lists[list];
328 if (curr == NULL)
329 gclog_or_tty->print_cr(" empty");
330 while (curr != NULL) {
331 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
332 HR_FORMAT_PARAMS(curr),
333 p2i(curr->prev_top_at_mark_start()),
334 p2i(curr->next_top_at_mark_start()),
335 curr->age_in_surv_rate_group_cond());
336 curr = curr->get_next_young_region();
337 }
338 }
339
340 gclog_or_tty->cr();
341 }
342
343 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
344 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
345 }
346
347 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
348 // The from card cache is not the memory that is actually committed. So we cannot
349 // take advantage of the zero_filled parameter.
350 reset_from_card_cache(start_idx, num_regions);
351 }
352
353 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
354 {
355 // Claim the right to put the region on the dirty cards region list
356 // by installing a self pointer.
357 HeapRegion* next = hr->get_next_dirty_cards_region();
358 if (next == NULL) {
359 HeapRegion* res = (HeapRegion*)
360 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
361 NULL);
362 if (res == NULL) {
363 HeapRegion* head;
364 do {
365 // Put the region to the dirty cards region list.
366 head = _dirty_cards_region_list;
367 next = (HeapRegion*)
368 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
369 if (next == head) {
370 assert(hr->get_next_dirty_cards_region() == hr,
371 "hr->get_next_dirty_cards_region() != hr");
372 if (next == NULL) {
373 // The last region in the list points to itself.
374 hr->set_next_dirty_cards_region(hr);
375 } else {
376 hr->set_next_dirty_cards_region(next);
377 }
378 }
379 } while (next != head);
380 }
381 }
382 }
383
384 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
385 {
386 HeapRegion* head;
387 HeapRegion* hr;
388 do {
389 head = _dirty_cards_region_list;
390 if (head == NULL) {
391 return NULL;
392 }
393 HeapRegion* new_head = head->get_next_dirty_cards_region();
394 if (head == new_head) {
395 // The last region.
396 new_head = NULL;
397 }
398 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
399 head);
400 } while (hr != head);
401 assert(hr != NULL, "invariant");
402 hr->set_next_dirty_cards_region(NULL);
403 return hr;
404 }
405
406 // Returns true if the reference points to an object that
407 // can move in an incremental collection.
408 bool G1CollectedHeap::is_scavengable(const void* p) {
409 HeapRegion* hr = heap_region_containing(p);
410 return !hr->is_pinned();
411 }
412
413 // Private methods.
414
415 HeapRegion*
416 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
417 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
418 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
419 if (!_secondary_free_list.is_empty()) {
420 if (G1ConcRegionFreeingVerbose) {
421 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
422 "secondary_free_list has %u entries",
423 _secondary_free_list.length());
424 }
425 // It looks as if there are free regions available on the
426 // secondary_free_list. Let's move them to the free_list and try
427 // again to allocate from it.
428 append_secondary_free_list();
429
430 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
431 "empty we should have moved at least one entry to the free_list");
432 HeapRegion* res = _hrm.allocate_free_region(is_old);
433 if (G1ConcRegionFreeingVerbose) {
434 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
435 "allocated " HR_FORMAT " from secondary_free_list",
436 HR_FORMAT_PARAMS(res));
437 }
438 return res;
439 }
440
441 // Wait here until we get notified either when (a) there are no
442 // more free regions coming or (b) some regions have been moved on
443 // the secondary_free_list.
444 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
445 }
446
447 if (G1ConcRegionFreeingVerbose) {
448 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
449 "could not allocate from secondary_free_list");
450 }
451 return NULL;
452 }
453
454 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
455 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
456 "the only time we use this to allocate a humongous region is "
457 "when we are allocating a single humongous region");
458
459 HeapRegion* res;
460 if (G1StressConcRegionFreeing) {
461 if (!_secondary_free_list.is_empty()) {
462 if (G1ConcRegionFreeingVerbose) {
463 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
464 "forced to look at the secondary_free_list");
465 }
466 res = new_region_try_secondary_free_list(is_old);
467 if (res != NULL) {
468 return res;
469 }
470 }
471 }
472
473 res = _hrm.allocate_free_region(is_old);
474
475 if (res == NULL) {
476 if (G1ConcRegionFreeingVerbose) {
477 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
478 "res == NULL, trying the secondary_free_list");
479 }
480 res = new_region_try_secondary_free_list(is_old);
481 }
482 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
483 // Currently, only attempts to allocate GC alloc regions set
484 // do_expand to true. So, we should only reach here during a
485 // safepoint. If this assumption changes we might have to
486 // reconsider the use of _expand_heap_after_alloc_failure.
487 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
488
489 ergo_verbose1(ErgoHeapSizing,
490 "attempt heap expansion",
491 ergo_format_reason("region allocation request failed")
492 ergo_format_byte("allocation request"),
493 word_size * HeapWordSize);
494 if (expand(word_size * HeapWordSize)) {
495 // Given that expand() succeeded in expanding the heap, and we
496 // always expand the heap by an amount aligned to the heap
497 // region size, the free list should in theory not be empty.
498 // In either case allocate_free_region() will check for NULL.
499 res = _hrm.allocate_free_region(is_old);
500 } else {
501 _expand_heap_after_alloc_failure = false;
502 }
503 }
504 return res;
505 }
506
507 HeapWord*
508 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
509 uint num_regions,
510 size_t word_size,
511 AllocationContext_t context) {
512 assert(first != G1_NO_HRM_INDEX, "pre-condition");
513 assert(is_humongous(word_size), "word_size should be humongous");
514 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
515
516 // Index of last region in the series + 1.
517 uint last = first + num_regions;
518
519 // We need to initialize the region(s) we just discovered. This is
520 // a bit tricky given that it can happen concurrently with
521 // refinement threads refining cards on these regions and
522 // potentially wanting to refine the BOT as they are scanning
523 // those cards (this can happen shortly after a cleanup; see CR
524 // 6991377). So we have to set up the region(s) carefully and in
525 // a specific order.
526
527 // The word size sum of all the regions we will allocate.
528 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
529 assert(word_size <= word_size_sum, "sanity");
530
531 // This will be the "starts humongous" region.
532 HeapRegion* first_hr = region_at(first);
533 // The header of the new object will be placed at the bottom of
534 // the first region.
535 HeapWord* new_obj = first_hr->bottom();
536 // This will be the new end of the first region in the series that
537 // should also match the end of the last region in the series.
538 HeapWord* new_end = new_obj + word_size_sum;
539 // This will be the new top of the first region that will reflect
540 // this allocation.
541 HeapWord* new_top = new_obj + word_size;
542
543 // First, we need to zero the header of the space that we will be
544 // allocating. When we update top further down, some refinement
545 // threads might try to scan the region. By zeroing the header we
546 // ensure that any thread that will try to scan the region will
547 // come across the zero klass word and bail out.
548 //
549 // NOTE: It would not have been correct to have used
550 // CollectedHeap::fill_with_object() and make the space look like
551 // an int array. The thread that is doing the allocation will
552 // later update the object header to a potentially different array
553 // type and, for a very short period of time, the klass and length
554 // fields will be inconsistent. This could cause a refinement
555 // thread to calculate the object size incorrectly.
556 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
557
558 // We will set up the first region as "starts humongous". This
559 // will also update the BOT covering all the regions to reflect
560 // that there is a single object that starts at the bottom of the
561 // first region.
562 first_hr->set_starts_humongous(new_top, new_end);
563 first_hr->set_allocation_context(context);
564 // Then, if there are any, we will set up the "continues
565 // humongous" regions.
566 HeapRegion* hr = NULL;
567 for (uint i = first + 1; i < last; ++i) {
568 hr = region_at(i);
569 hr->set_continues_humongous(first_hr);
570 hr->set_allocation_context(context);
571 }
572 // If we have "continues humongous" regions (hr != NULL), then the
573 // end of the last one should match new_end.
574 assert(hr == NULL || hr->end() == new_end, "sanity");
575
576 // Up to this point no concurrent thread would have been able to
577 // do any scanning on any region in this series. All the top
578 // fields still point to bottom, so the intersection between
579 // [bottom,top] and [card_start,card_end] will be empty. Before we
580 // update the top fields, we'll do a storestore to make sure that
581 // no thread sees the update to top before the zeroing of the
582 // object header and the BOT initialization.
583 OrderAccess::storestore();
584
585 // Now that the BOT and the object header have been initialized,
586 // we can update top of the "starts humongous" region.
587 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
588 "new_top should be in this region");
589 first_hr->set_top(new_top);
590 if (_hr_printer.is_active()) {
591 HeapWord* bottom = first_hr->bottom();
592 HeapWord* end = first_hr->orig_end();
593 if ((first + 1) == last) {
594 // the series has a single humongous region
595 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
596 } else {
597 // the series has more than one humongous regions
598 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
599 }
600 }
601
602 // Now, we will update the top fields of the "continues humongous"
603 // regions. The reason we need to do this is that, otherwise,
604 // these regions would look empty and this will confuse parts of
605 // G1. For example, the code that looks for a consecutive number
606 // of empty regions will consider them empty and try to
607 // re-allocate them. We can extend is_empty() to also include
608 // !is_continues_humongous(), but it is easier to just update the top
609 // fields here. The way we set top for all regions (i.e., top ==
610 // end for all regions but the last one, top == new_top for the
611 // last one) is actually used when we will free up the humongous
612 // region in free_humongous_region().
613 hr = NULL;
614 for (uint i = first + 1; i < last; ++i) {
615 hr = region_at(i);
616 if ((i + 1) == last) {
617 // last continues humongous region
618 assert(hr->bottom() < new_top && new_top <= hr->end(),
619 "new_top should fall on this region");
620 hr->set_top(new_top);
621 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
622 } else {
623 // not last one
624 assert(new_top > hr->end(), "new_top should be above this region");
625 hr->set_top(hr->end());
626 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
627 }
628 }
629 // If we have continues humongous regions (hr != NULL), then the
630 // end of the last one should match new_end and its top should
631 // match new_top.
632 assert(hr == NULL ||
633 (hr->end() == new_end && hr->top() == new_top), "sanity");
634 check_bitmaps("Humongous Region Allocation", first_hr);
635
636 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
637 increase_used(first_hr->used());
638 _humongous_set.add(first_hr);
639
640 return new_obj;
641 }
642
643 // If could fit into free regions w/o expansion, try.
644 // Otherwise, if can expand, do so.
645 // Otherwise, if using ex regions might help, try with ex given back.
646 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
647 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
648
649 verify_region_sets_optional();
650
651 uint first = G1_NO_HRM_INDEX;
652 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
653
654 if (obj_regions == 1) {
655 // Only one region to allocate, try to use a fast path by directly allocating
656 // from the free lists. Do not try to expand here, we will potentially do that
657 // later.
658 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
659 if (hr != NULL) {
660 first = hr->hrm_index();
661 }
662 } else {
663 // We can't allocate humongous regions spanning more than one region while
664 // cleanupComplete() is running, since some of the regions we find to be
665 // empty might not yet be added to the free list. It is not straightforward
666 // to know in which list they are on so that we can remove them. We only
667 // need to do this if we need to allocate more than one region to satisfy the
668 // current humongous allocation request. If we are only allocating one region
669 // we use the one-region region allocation code (see above), that already
670 // potentially waits for regions from the secondary free list.
671 wait_while_free_regions_coming();
672 append_secondary_free_list_if_not_empty_with_lock();
673
674 // Policy: Try only empty regions (i.e. already committed first). Maybe we
675 // are lucky enough to find some.
676 first = _hrm.find_contiguous_only_empty(obj_regions);
677 if (first != G1_NO_HRM_INDEX) {
678 _hrm.allocate_free_regions_starting_at(first, obj_regions);
679 }
680 }
681
682 if (first == G1_NO_HRM_INDEX) {
683 // Policy: We could not find enough regions for the humongous object in the
684 // free list. Look through the heap to find a mix of free and uncommitted regions.
685 // If so, try expansion.
686 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
687 if (first != G1_NO_HRM_INDEX) {
688 // We found something. Make sure these regions are committed, i.e. expand
689 // the heap. Alternatively we could do a defragmentation GC.
690 ergo_verbose1(ErgoHeapSizing,
691 "attempt heap expansion",
692 ergo_format_reason("humongous allocation request failed")
693 ergo_format_byte("allocation request"),
694 word_size * HeapWordSize);
695
696 _hrm.expand_at(first, obj_regions);
697 g1_policy()->record_new_heap_size(num_regions());
698
699 #ifdef ASSERT
700 for (uint i = first; i < first + obj_regions; ++i) {
701 HeapRegion* hr = region_at(i);
702 assert(hr->is_free(), "sanity");
703 assert(hr->is_empty(), "sanity");
704 assert(is_on_master_free_list(hr), "sanity");
705 }
706 #endif
707 _hrm.allocate_free_regions_starting_at(first, obj_regions);
708 } else {
709 // Policy: Potentially trigger a defragmentation GC.
710 }
711 }
712
713 HeapWord* result = NULL;
714 if (first != G1_NO_HRM_INDEX) {
715 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
716 word_size, context);
717 assert(result != NULL, "it should always return a valid result");
718
719 // A successful humongous object allocation changes the used space
720 // information of the old generation so we need to recalculate the
721 // sizes and update the jstat counters here.
722 g1mm()->update_sizes();
723 }
724
725 verify_region_sets_optional();
726
727 return result;
728 }
729
730 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
731 assert_heap_not_locked_and_not_at_safepoint();
732 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
733
734 uint dummy_gc_count_before;
735 uint dummy_gclocker_retry_count = 0;
736 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
737 }
738
739 HeapWord*
740 G1CollectedHeap::mem_allocate(size_t word_size,
741 bool* gc_overhead_limit_was_exceeded) {
742 assert_heap_not_locked_and_not_at_safepoint();
743
744 // Loop until the allocation is satisfied, or unsatisfied after GC.
745 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
746 uint gc_count_before;
747
748 HeapWord* result = NULL;
749 if (!is_humongous(word_size)) {
750 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
751 } else {
752 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
753 }
754 if (result != NULL) {
755 return result;
756 }
757
758 // Create the garbage collection operation...
759 VM_G1CollectForAllocation op(gc_count_before, word_size);
760 op.set_allocation_context(AllocationContext::current());
761
762 // ...and get the VM thread to execute it.
763 VMThread::execute(&op);
764
765 if (op.prologue_succeeded() && op.pause_succeeded()) {
766 // If the operation was successful we'll return the result even
767 // if it is NULL. If the allocation attempt failed immediately
768 // after a Full GC, it's unlikely we'll be able to allocate now.
769 HeapWord* result = op.result();
770 if (result != NULL && !is_humongous(word_size)) {
771 // Allocations that take place on VM operations do not do any
772 // card dirtying and we have to do it here. We only have to do
773 // this for non-humongous allocations, though.
774 dirty_young_block(result, word_size);
775 }
776 return result;
777 } else {
778 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
779 return NULL;
780 }
781 assert(op.result() == NULL,
782 "the result should be NULL if the VM op did not succeed");
783 }
784
785 // Give a warning if we seem to be looping forever.
786 if ((QueuedAllocationWarningCount > 0) &&
787 (try_count % QueuedAllocationWarningCount == 0)) {
788 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
789 }
790 }
791
792 ShouldNotReachHere();
793 return NULL;
794 }
795
796 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
797 AllocationContext_t context,
798 uint* gc_count_before_ret,
799 uint* gclocker_retry_count_ret) {
800 // Make sure you read the note in attempt_allocation_humongous().
801
802 assert_heap_not_locked_and_not_at_safepoint();
803 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
804 "be called for humongous allocation requests");
805
806 // We should only get here after the first-level allocation attempt
807 // (attempt_allocation()) failed to allocate.
808
809 // We will loop until a) we manage to successfully perform the
810 // allocation or b) we successfully schedule a collection which
811 // fails to perform the allocation. b) is the only case when we'll
812 // return NULL.
813 HeapWord* result = NULL;
814 for (int try_count = 1; /* we'll return */; try_count += 1) {
815 bool should_try_gc;
816 uint gc_count_before;
817
818 {
819 MutexLockerEx x(Heap_lock);
820 result = _allocator->attempt_allocation_locked(word_size, context);
821 if (result != NULL) {
822 return result;
823 }
824
825 if (GC_locker::is_active_and_needs_gc()) {
826 if (g1_policy()->can_expand_young_list()) {
827 // No need for an ergo verbose message here,
828 // can_expand_young_list() does this when it returns true.
829 result = _allocator->attempt_allocation_force(word_size, context);
830 if (result != NULL) {
831 return result;
832 }
833 }
834 should_try_gc = false;
835 } else {
836 // The GCLocker may not be active but the GCLocker initiated
837 // GC may not yet have been performed (GCLocker::needs_gc()
838 // returns true). In this case we do not try this GC and
839 // wait until the GCLocker initiated GC is performed, and
840 // then retry the allocation.
841 if (GC_locker::needs_gc()) {
842 should_try_gc = false;
843 } else {
844 // Read the GC count while still holding the Heap_lock.
845 gc_count_before = total_collections();
846 should_try_gc = true;
847 }
848 }
849 }
850
851 if (should_try_gc) {
852 bool succeeded;
853 result = do_collection_pause(word_size, gc_count_before, &succeeded,
854 GCCause::_g1_inc_collection_pause);
855 if (result != NULL) {
856 assert(succeeded, "only way to get back a non-NULL result");
857 return result;
858 }
859
860 if (succeeded) {
861 // If we get here we successfully scheduled a collection which
862 // failed to allocate. No point in trying to allocate
863 // further. We'll just return NULL.
864 MutexLockerEx x(Heap_lock);
865 *gc_count_before_ret = total_collections();
866 return NULL;
867 }
868 } else {
869 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
870 MutexLockerEx x(Heap_lock);
871 *gc_count_before_ret = total_collections();
872 return NULL;
873 }
874 // The GCLocker is either active or the GCLocker initiated
875 // GC has not yet been performed. Stall until it is and
876 // then retry the allocation.
877 GC_locker::stall_until_clear();
878 (*gclocker_retry_count_ret) += 1;
879 }
880
881 // We can reach here if we were unsuccessful in scheduling a
882 // collection (because another thread beat us to it) or if we were
883 // stalled due to the GC locker. In either can we should retry the
884 // allocation attempt in case another thread successfully
885 // performed a collection and reclaimed enough space. We do the
886 // first attempt (without holding the Heap_lock) here and the
887 // follow-on attempt will be at the start of the next loop
888 // iteration (after taking the Heap_lock).
889 result = _allocator->attempt_allocation(word_size, context);
890 if (result != NULL) {
891 return result;
892 }
893
894 // Give a warning if we seem to be looping forever.
895 if ((QueuedAllocationWarningCount > 0) &&
896 (try_count % QueuedAllocationWarningCount == 0)) {
897 warning("G1CollectedHeap::attempt_allocation_slow() "
898 "retries %d times", try_count);
899 }
900 }
901
902 ShouldNotReachHere();
903 return NULL;
904 }
905
906 void G1CollectedHeap::begin_archive_alloc_range() {
907 assert_at_safepoint(true /* should_be_vm_thread */);
908 if (_archive_allocator == NULL) {
909 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
910 }
911 }
912
913 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
914 // Allocations in archive regions cannot be of a size that would be considered
915 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
916 // may be different at archive-restore time.
917 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
918 }
919
920 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
921 assert_at_safepoint(true /* should_be_vm_thread */);
922 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
923 if (is_archive_alloc_too_large(word_size)) {
924 return NULL;
925 }
926 return _archive_allocator->archive_mem_allocate(word_size);
927 }
928
929 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
930 size_t end_alignment_in_bytes) {
931 assert_at_safepoint(true /* should_be_vm_thread */);
932 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
933
934 // Call complete_archive to do the real work, filling in the MemRegion
935 // array with the archive regions.
936 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
937 delete _archive_allocator;
938 _archive_allocator = NULL;
939 }
940
941 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
942 assert(ranges != NULL, "MemRegion array NULL");
943 assert(count != 0, "No MemRegions provided");
944 MemRegion reserved = _hrm.reserved();
945 for (size_t i = 0; i < count; i++) {
946 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
947 return false;
948 }
949 }
950 return true;
951 }
952
953 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
954 assert(!is_init_completed(), "Expect to be called at JVM init time");
955 assert(ranges != NULL, "MemRegion array NULL");
956 assert(count != 0, "No MemRegions provided");
957 MutexLockerEx x(Heap_lock);
958
959 MemRegion reserved = _hrm.reserved();
960 HeapWord* prev_last_addr = NULL;
961 HeapRegion* prev_last_region = NULL;
962
963 // Temporarily disable pretouching of heap pages. This interface is used
964 // when mmap'ing archived heap data in, so pre-touching is wasted.
965 FlagSetting fs(AlwaysPreTouch, false);
966
967 // Enable archive object checking in G1MarkSweep. We have to let it know
968 // about each archive range, so that objects in those ranges aren't marked.
969 G1MarkSweep::enable_archive_object_check();
970
971 // For each specified MemRegion range, allocate the corresponding G1
972 // regions and mark them as archive regions. We expect the ranges in
973 // ascending starting address order, without overlap.
974 for (size_t i = 0; i < count; i++) {
975 MemRegion curr_range = ranges[i];
976 HeapWord* start_address = curr_range.start();
977 size_t word_size = curr_range.word_size();
978 HeapWord* last_address = curr_range.last();
979 size_t commits = 0;
980
981 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
982 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
983 p2i(start_address), p2i(last_address)));
984 guarantee(start_address > prev_last_addr,
985 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
986 p2i(start_address), p2i(prev_last_addr)));
987 prev_last_addr = last_address;
988
989 // Check for ranges that start in the same G1 region in which the previous
990 // range ended, and adjust the start address so we don't try to allocate
991 // the same region again. If the current range is entirely within that
992 // region, skip it, just adjusting the recorded top.
993 HeapRegion* start_region = _hrm.addr_to_region(start_address);
994 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
995 start_address = start_region->end();
996 if (start_address > last_address) {
997 increase_used(word_size * HeapWordSize);
998 start_region->set_top(last_address + 1);
999 continue;
1000 }
1001 start_region->set_top(start_address);
1002 curr_range = MemRegion(start_address, last_address + 1);
1003 start_region = _hrm.addr_to_region(start_address);
1004 }
1005
1006 // Perform the actual region allocation, exiting if it fails.
1007 // Then note how much new space we have allocated.
1008 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1009 return false;
1010 }
1011 increase_used(word_size * HeapWordSize);
1012 if (commits != 0) {
1013 ergo_verbose1(ErgoHeapSizing,
1014 "attempt heap expansion",
1015 ergo_format_reason("allocate archive regions")
1016 ergo_format_byte("total size"),
1017 HeapRegion::GrainWords * HeapWordSize * commits);
1018 }
1019
1020 // Mark each G1 region touched by the range as archive, add it to the old set,
1021 // and set the allocation context and top.
1022 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1023 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1024 prev_last_region = last_region;
1025
1026 while (curr_region != NULL) {
1027 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1028 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1029 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1030 curr_region->set_allocation_context(AllocationContext::system());
1031 curr_region->set_archive();
1032 _old_set.add(curr_region);
1033 if (curr_region != last_region) {
1034 curr_region->set_top(curr_region->end());
1035 curr_region = _hrm.next_region_in_heap(curr_region);
1036 } else {
1037 curr_region->set_top(last_address + 1);
1038 curr_region = NULL;
1039 }
1040 }
1041
1042 // Notify mark-sweep of the archive range.
1043 G1MarkSweep::set_range_archive(curr_range, true);
1044 }
1045 return true;
1046 }
1047
1048 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1049 assert(!is_init_completed(), "Expect to be called at JVM init time");
1050 assert(ranges != NULL, "MemRegion array NULL");
1051 assert(count != 0, "No MemRegions provided");
1052 MemRegion reserved = _hrm.reserved();
1053 HeapWord *prev_last_addr = NULL;
1054 HeapRegion* prev_last_region = NULL;
1055
1056 // For each MemRegion, create filler objects, if needed, in the G1 regions
1057 // that contain the address range. The address range actually within the
1058 // MemRegion will not be modified. That is assumed to have been initialized
1059 // elsewhere, probably via an mmap of archived heap data.
1060 MutexLockerEx x(Heap_lock);
1061 for (size_t i = 0; i < count; i++) {
1062 HeapWord* start_address = ranges[i].start();
1063 HeapWord* last_address = ranges[i].last();
1064
1065 assert(reserved.contains(start_address) && reserved.contains(last_address),
1066 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1067 p2i(start_address), p2i(last_address)));
1068 assert(start_address > prev_last_addr,
1069 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1070 p2i(start_address), p2i(prev_last_addr)));
1071
1072 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1073 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1074 HeapWord* bottom_address = start_region->bottom();
1075
1076 // Check for a range beginning in the same region in which the
1077 // previous one ended.
1078 if (start_region == prev_last_region) {
1079 bottom_address = prev_last_addr + 1;
1080 }
1081
1082 // Verify that the regions were all marked as archive regions by
1083 // alloc_archive_regions.
1084 HeapRegion* curr_region = start_region;
1085 while (curr_region != NULL) {
1086 guarantee(curr_region->is_archive(),
1087 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1088 if (curr_region != last_region) {
1089 curr_region = _hrm.next_region_in_heap(curr_region);
1090 } else {
1091 curr_region = NULL;
1092 }
1093 }
1094
1095 prev_last_addr = last_address;
1096 prev_last_region = last_region;
1097
1098 // Fill the memory below the allocated range with dummy object(s),
1099 // if the region bottom does not match the range start, or if the previous
1100 // range ended within the same G1 region, and there is a gap.
1101 if (start_address != bottom_address) {
1102 size_t fill_size = pointer_delta(start_address, bottom_address);
1103 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1104 increase_used(fill_size * HeapWordSize);
1105 }
1106 }
1107 }
1108
1109 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1110 uint* gc_count_before_ret,
1111 uint* gclocker_retry_count_ret) {
1112 assert_heap_not_locked_and_not_at_safepoint();
1113 assert(!is_humongous(word_size), "attempt_allocation() should not "
1114 "be called for humongous allocation requests");
1115
1116 AllocationContext_t context = AllocationContext::current();
1117 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1118
1119 if (result == NULL) {
1120 result = attempt_allocation_slow(word_size,
1121 context,
1122 gc_count_before_ret,
1123 gclocker_retry_count_ret);
1124 }
1125 assert_heap_not_locked();
1126 if (result != NULL) {
1127 dirty_young_block(result, word_size);
1128 }
1129 return result;
1130 }
1131
1132 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1133 assert(!is_init_completed(), "Expect to be called at JVM init time");
1134 assert(ranges != NULL, "MemRegion array NULL");
1135 assert(count != 0, "No MemRegions provided");
1136 MemRegion reserved = _hrm.reserved();
1137 HeapWord* prev_last_addr = NULL;
1138 HeapRegion* prev_last_region = NULL;
1139 size_t size_used = 0;
1140 size_t uncommitted_regions = 0;
1141
1142 // For each Memregion, free the G1 regions that constitute it, and
1143 // notify mark-sweep that the range is no longer to be considered 'archive.'
1144 MutexLockerEx x(Heap_lock);
1145 for (size_t i = 0; i < count; i++) {
1146 HeapWord* start_address = ranges[i].start();
1147 HeapWord* last_address = ranges[i].last();
1148
1149 assert(reserved.contains(start_address) && reserved.contains(last_address),
1150 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1151 p2i(start_address), p2i(last_address)));
1152 assert(start_address > prev_last_addr,
1153 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1154 p2i(start_address), p2i(prev_last_addr)));
1155 size_used += ranges[i].byte_size();
1156 prev_last_addr = last_address;
1157
1158 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1159 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1160
1161 // Check for ranges that start in the same G1 region in which the previous
1162 // range ended, and adjust the start address so we don't try to free
1163 // the same region again. If the current range is entirely within that
1164 // region, skip it.
1165 if (start_region == prev_last_region) {
1166 start_address = start_region->end();
1167 if (start_address > last_address) {
1168 continue;
1169 }
1170 start_region = _hrm.addr_to_region(start_address);
1171 }
1172 prev_last_region = last_region;
1173
1174 // After verifying that each region was marked as an archive region by
1175 // alloc_archive_regions, set it free and empty and uncommit it.
1176 HeapRegion* curr_region = start_region;
1177 while (curr_region != NULL) {
1178 guarantee(curr_region->is_archive(),
1179 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1180 uint curr_index = curr_region->hrm_index();
1181 _old_set.remove(curr_region);
1182 curr_region->set_free();
1183 curr_region->set_top(curr_region->bottom());
1184 if (curr_region != last_region) {
1185 curr_region = _hrm.next_region_in_heap(curr_region);
1186 } else {
1187 curr_region = NULL;
1188 }
1189 _hrm.shrink_at(curr_index, 1);
1190 uncommitted_regions++;
1191 }
1192
1193 // Notify mark-sweep that this is no longer an archive range.
1194 G1MarkSweep::set_range_archive(ranges[i], false);
1195 }
1196
1197 if (uncommitted_regions != 0) {
1198 ergo_verbose1(ErgoHeapSizing,
1199 "attempt heap shrinking",
1200 ergo_format_reason("uncommitted archive regions")
1201 ergo_format_byte("total size"),
1202 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1203 }
1204 decrease_used(size_used);
1205 }
1206
1207 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1208 uint* gc_count_before_ret,
1209 uint* gclocker_retry_count_ret) {
1210 // The structure of this method has a lot of similarities to
1211 // attempt_allocation_slow(). The reason these two were not merged
1212 // into a single one is that such a method would require several "if
1213 // allocation is not humongous do this, otherwise do that"
1214 // conditional paths which would obscure its flow. In fact, an early
1215 // version of this code did use a unified method which was harder to
1216 // follow and, as a result, it had subtle bugs that were hard to
1217 // track down. So keeping these two methods separate allows each to
1218 // be more readable. It will be good to keep these two in sync as
1219 // much as possible.
1220
1221 assert_heap_not_locked_and_not_at_safepoint();
1222 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1223 "should only be called for humongous allocations");
1224
1225 // Humongous objects can exhaust the heap quickly, so we should check if we
1226 // need to start a marking cycle at each humongous object allocation. We do
1227 // the check before we do the actual allocation. The reason for doing it
1228 // before the allocation is that we avoid having to keep track of the newly
1229 // allocated memory while we do a GC.
1230 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1231 word_size)) {
1232 collect(GCCause::_g1_humongous_allocation);
1233 }
1234
1235 // We will loop until a) we manage to successfully perform the
1236 // allocation or b) we successfully schedule a collection which
1237 // fails to perform the allocation. b) is the only case when we'll
1238 // return NULL.
1239 HeapWord* result = NULL;
1240 for (int try_count = 1; /* we'll return */; try_count += 1) {
1241 bool should_try_gc;
1242 uint gc_count_before;
1243
1244 {
1245 MutexLockerEx x(Heap_lock);
1246
1247 // Given that humongous objects are not allocated in young
1248 // regions, we'll first try to do the allocation without doing a
1249 // collection hoping that there's enough space in the heap.
1250 result = humongous_obj_allocate(word_size, AllocationContext::current());
1251 if (result != NULL) {
1252 return result;
1253 }
1254
1255 if (GC_locker::is_active_and_needs_gc()) {
1256 should_try_gc = false;
1257 } else {
1258 // The GCLocker may not be active but the GCLocker initiated
1259 // GC may not yet have been performed (GCLocker::needs_gc()
1260 // returns true). In this case we do not try this GC and
1261 // wait until the GCLocker initiated GC is performed, and
1262 // then retry the allocation.
1263 if (GC_locker::needs_gc()) {
1264 should_try_gc = false;
1265 } else {
1266 // Read the GC count while still holding the Heap_lock.
1267 gc_count_before = total_collections();
1268 should_try_gc = true;
1269 }
1270 }
1271 }
1272
1273 if (should_try_gc) {
1274 // If we failed to allocate the humongous object, we should try to
1275 // do a collection pause (if we're allowed) in case it reclaims
1276 // enough space for the allocation to succeed after the pause.
1277
1278 bool succeeded;
1279 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1280 GCCause::_g1_humongous_allocation);
1281 if (result != NULL) {
1282 assert(succeeded, "only way to get back a non-NULL result");
1283 return result;
1284 }
1285
1286 if (succeeded) {
1287 // If we get here we successfully scheduled a collection which
1288 // failed to allocate. No point in trying to allocate
1289 // further. We'll just return NULL.
1290 MutexLockerEx x(Heap_lock);
1291 *gc_count_before_ret = total_collections();
1292 return NULL;
1293 }
1294 } else {
1295 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1296 MutexLockerEx x(Heap_lock);
1297 *gc_count_before_ret = total_collections();
1298 return NULL;
1299 }
1300 // The GCLocker is either active or the GCLocker initiated
1301 // GC has not yet been performed. Stall until it is and
1302 // then retry the allocation.
1303 GC_locker::stall_until_clear();
1304 (*gclocker_retry_count_ret) += 1;
1305 }
1306
1307 // We can reach here if we were unsuccessful in scheduling a
1308 // collection (because another thread beat us to it) or if we were
1309 // stalled due to the GC locker. In either can we should retry the
1310 // allocation attempt in case another thread successfully
1311 // performed a collection and reclaimed enough space. Give a
1312 // warning if we seem to be looping forever.
1313
1314 if ((QueuedAllocationWarningCount > 0) &&
1315 (try_count % QueuedAllocationWarningCount == 0)) {
1316 warning("G1CollectedHeap::attempt_allocation_humongous() "
1317 "retries %d times", try_count);
1318 }
1319 }
1320
1321 ShouldNotReachHere();
1322 return NULL;
1323 }
1324
1325 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1326 AllocationContext_t context,
1327 bool expect_null_mutator_alloc_region) {
1328 assert_at_safepoint(true /* should_be_vm_thread */);
1329 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1330 "the current alloc region was unexpectedly found to be non-NULL");
1331
1332 if (!is_humongous(word_size)) {
1333 return _allocator->attempt_allocation_locked(word_size, context);
1334 } else {
1335 HeapWord* result = humongous_obj_allocate(word_size, context);
1336 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1337 collector_state()->set_initiate_conc_mark_if_possible(true);
1338 }
1339 return result;
1340 }
1341
1342 ShouldNotReachHere();
1343 }
1344
1345 class PostMCRemSetClearClosure: public HeapRegionClosure {
1346 G1CollectedHeap* _g1h;
1347 ModRefBarrierSet* _mr_bs;
1348 public:
1349 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1350 _g1h(g1h), _mr_bs(mr_bs) {}
1351
1352 bool doHeapRegion(HeapRegion* r) {
1353 HeapRegionRemSet* hrrs = r->rem_set();
1354
1355 if (r->is_continues_humongous()) {
1356 // We'll assert that the strong code root list and RSet is empty
1357 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1358 assert(hrrs->occupied() == 0, "RSet should be empty");
1359 return false;
1360 }
1361
1362 _g1h->reset_gc_time_stamps(r);
1363 hrrs->clear();
1364 // You might think here that we could clear just the cards
1365 // corresponding to the used region. But no: if we leave a dirty card
1366 // in a region we might allocate into, then it would prevent that card
1367 // from being enqueued, and cause it to be missed.
1368 // Re: the performance cost: we shouldn't be doing full GC anyway!
1369 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1370
1371 return false;
1372 }
1373 };
1374
1375 void G1CollectedHeap::clear_rsets_post_compaction() {
1376 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1377 heap_region_iterate(&rs_clear);
1378 }
1379
1380 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1381 G1CollectedHeap* _g1h;
1382 UpdateRSOopClosure _cl;
1383 public:
1384 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1385 _cl(g1->g1_rem_set(), worker_i),
1386 _g1h(g1)
1387 { }
1388
1389 bool doHeapRegion(HeapRegion* r) {
1390 if (!r->is_continues_humongous()) {
1391 _cl.set_from(r);
1392 r->oop_iterate(&_cl);
1393 }
1394 return false;
1395 }
1396 };
1397
1398 class ParRebuildRSTask: public AbstractGangTask {
1399 G1CollectedHeap* _g1;
1400 HeapRegionClaimer _hrclaimer;
1401
1402 public:
1403 ParRebuildRSTask(G1CollectedHeap* g1) :
1404 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1405
1406 void work(uint worker_id) {
1407 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1408 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1409 }
1410 };
1411
1412 class PostCompactionPrinterClosure: public HeapRegionClosure {
1413 private:
1414 G1HRPrinter* _hr_printer;
1415 public:
1416 bool doHeapRegion(HeapRegion* hr) {
1417 assert(!hr->is_young(), "not expecting to find young regions");
1418 if (hr->is_free()) {
1419 // We only generate output for non-empty regions.
1420 } else if (hr->is_starts_humongous()) {
1421 if (hr->region_num() == 1) {
1422 // single humongous region
1423 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1424 } else {
1425 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1426 }
1427 } else if (hr->is_continues_humongous()) {
1428 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1429 } else if (hr->is_archive()) {
1430 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1431 } else if (hr->is_old()) {
1432 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1433 } else {
1434 ShouldNotReachHere();
1435 }
1436 return false;
1437 }
1438
1439 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1440 : _hr_printer(hr_printer) { }
1441 };
1442
1443 void G1CollectedHeap::print_hrm_post_compaction() {
1444 PostCompactionPrinterClosure cl(hr_printer());
1445 heap_region_iterate(&cl);
1446 }
1447
1448 bool G1CollectedHeap::do_collection(bool explicit_gc,
1449 bool clear_all_soft_refs,
1450 size_t word_size) {
1451 assert_at_safepoint(true /* should_be_vm_thread */);
1452
1453 if (GC_locker::check_active_before_gc()) {
1454 return false;
1455 }
1456
1457 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1458 gc_timer->register_gc_start();
1459
1460 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1461 GCIdMark gc_id_mark;
1462 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1463
1464 SvcGCMarker sgcm(SvcGCMarker::FULL);
1465 ResourceMark rm;
1466
1467 G1Log::update_level();
1468 print_heap_before_gc();
1469 trace_heap_before_gc(gc_tracer);
1470
1471 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1472
1473 verify_region_sets_optional();
1474
1475 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1476 collector_policy()->should_clear_all_soft_refs();
1477
1478 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1479
1480 {
1481 IsGCActiveMark x;
1482
1483 // Timing
1484 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1485 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1486
1487 {
1488 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1489 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1490 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1491
1492 g1_policy()->record_full_collection_start();
1493
1494 // Note: When we have a more flexible GC logging framework that
1495 // allows us to add optional attributes to a GC log record we
1496 // could consider timing and reporting how long we wait in the
1497 // following two methods.
1498 wait_while_free_regions_coming();
1499 // If we start the compaction before the CM threads finish
1500 // scanning the root regions we might trip them over as we'll
1501 // be moving objects / updating references. So let's wait until
1502 // they are done. By telling them to abort, they should complete
1503 // early.
1504 _cm->root_regions()->abort();
1505 _cm->root_regions()->wait_until_scan_finished();
1506 append_secondary_free_list_if_not_empty_with_lock();
1507
1508 gc_prologue(true);
1509 increment_total_collections(true /* full gc */);
1510 increment_old_marking_cycles_started();
1511
1512 assert(used() == recalculate_used(), "Should be equal");
1513
1514 verify_before_gc();
1515
1516 check_bitmaps("Full GC Start");
1517 pre_full_gc_dump(gc_timer);
1518
1519 COMPILER2_PRESENT(DerivedPointerTable::clear());
1520
1521 // Disable discovery and empty the discovered lists
1522 // for the CM ref processor.
1523 ref_processor_cm()->disable_discovery();
1524 ref_processor_cm()->abandon_partial_discovery();
1525 ref_processor_cm()->verify_no_references_recorded();
1526
1527 // Abandon current iterations of concurrent marking and concurrent
1528 // refinement, if any are in progress. We have to do this before
1529 // wait_until_scan_finished() below.
1530 concurrent_mark()->abort();
1531
1532 // Make sure we'll choose a new allocation region afterwards.
1533 _allocator->release_mutator_alloc_region();
1534 _allocator->abandon_gc_alloc_regions();
1535 g1_rem_set()->cleanupHRRS();
1536
1537 // We should call this after we retire any currently active alloc
1538 // regions so that all the ALLOC / RETIRE events are generated
1539 // before the start GC event.
1540 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1541
1542 // We may have added regions to the current incremental collection
1543 // set between the last GC or pause and now. We need to clear the
1544 // incremental collection set and then start rebuilding it afresh
1545 // after this full GC.
1546 abandon_collection_set(g1_policy()->inc_cset_head());
1547 g1_policy()->clear_incremental_cset();
1548 g1_policy()->stop_incremental_cset_building();
1549
1550 tear_down_region_sets(false /* free_list_only */);
1551 collector_state()->set_gcs_are_young(true);
1552
1553 // See the comments in g1CollectedHeap.hpp and
1554 // G1CollectedHeap::ref_processing_init() about
1555 // how reference processing currently works in G1.
1556
1557 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1558 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1559
1560 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1561 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1562
1563 ref_processor_stw()->enable_discovery();
1564 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1565
1566 // Do collection work
1567 {
1568 HandleMark hm; // Discard invalid handles created during gc
1569 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1570 }
1571
1572 assert(num_free_regions() == 0, "we should not have added any free regions");
1573 rebuild_region_sets(false /* free_list_only */);
1574
1575 // Enqueue any discovered reference objects that have
1576 // not been removed from the discovered lists.
1577 ref_processor_stw()->enqueue_discovered_references();
1578
1579 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1580
1581 MemoryService::track_memory_usage();
1582
1583 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1584 ref_processor_stw()->verify_no_references_recorded();
1585
1586 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1587 ClassLoaderDataGraph::purge();
1588 MetaspaceAux::verify_metrics();
1589
1590 // Note: since we've just done a full GC, concurrent
1591 // marking is no longer active. Therefore we need not
1592 // re-enable reference discovery for the CM ref processor.
1593 // That will be done at the start of the next marking cycle.
1594 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1595 ref_processor_cm()->verify_no_references_recorded();
1596
1597 reset_gc_time_stamp();
1598 // Since everything potentially moved, we will clear all remembered
1599 // sets, and clear all cards. Later we will rebuild remembered
1600 // sets. We will also reset the GC time stamps of the regions.
1601 clear_rsets_post_compaction();
1602 check_gc_time_stamps();
1603
1604 // Resize the heap if necessary.
1605 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1606
1607 if (_hr_printer.is_active()) {
1608 // We should do this after we potentially resize the heap so
1609 // that all the COMMIT / UNCOMMIT events are generated before
1610 // the end GC event.
1611
1612 print_hrm_post_compaction();
1613 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1614 }
1615
1616 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1617 if (hot_card_cache->use_cache()) {
1618 hot_card_cache->reset_card_counts();
1619 hot_card_cache->reset_hot_cache();
1620 }
1621
1622 // Rebuild remembered sets of all regions.
1623 uint n_workers =
1624 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1625 workers()->active_workers(),
1626 Threads::number_of_non_daemon_threads());
1627 workers()->set_active_workers(n_workers);
1628
1629 ParRebuildRSTask rebuild_rs_task(this);
1630 workers()->run_task(&rebuild_rs_task);
1631
1632 // Rebuild the strong code root lists for each region
1633 rebuild_strong_code_roots();
1634
1635 if (true) { // FIXME
1636 MetaspaceGC::compute_new_size();
1637 }
1638
1639 #ifdef TRACESPINNING
1640 ParallelTaskTerminator::print_termination_counts();
1641 #endif
1642
1643 // Discard all rset updates
1644 JavaThread::dirty_card_queue_set().abandon_logs();
1645 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1646
1647 _young_list->reset_sampled_info();
1648 // At this point there should be no regions in the
1649 // entire heap tagged as young.
1650 assert(check_young_list_empty(true /* check_heap */),
1651 "young list should be empty at this point");
1652
1653 // Update the number of full collections that have been completed.
1654 increment_old_marking_cycles_completed(false /* concurrent */);
1655
1656 _hrm.verify_optional();
1657 verify_region_sets_optional();
1658
1659 verify_after_gc();
1660
1661 // Clear the previous marking bitmap, if needed for bitmap verification.
1662 // Note we cannot do this when we clear the next marking bitmap in
1663 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1664 // objects marked during a full GC against the previous bitmap.
1665 // But we need to clear it before calling check_bitmaps below since
1666 // the full GC has compacted objects and updated TAMS but not updated
1667 // the prev bitmap.
1668 if (G1VerifyBitmaps) {
1669 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1670 }
1671 check_bitmaps("Full GC End");
1672
1673 // Start a new incremental collection set for the next pause
1674 assert(g1_policy()->collection_set() == NULL, "must be");
1675 g1_policy()->start_incremental_cset_building();
1676
1677 clear_cset_fast_test();
1678
1679 _allocator->init_mutator_alloc_region();
1680
1681 g1_policy()->record_full_collection_end();
1682
1683 if (G1Log::fine()) {
1684 g1_policy()->print_heap_transition();
1685 }
1686
1687 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1688 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1689 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1690 // before any GC notifications are raised.
1691 g1mm()->update_sizes();
1692
1693 gc_epilogue(true);
1694 }
1695
1696 if (G1Log::finer()) {
1697 g1_policy()->print_detailed_heap_transition(true /* full */);
1698 }
1699
1700 print_heap_after_gc();
1701 trace_heap_after_gc(gc_tracer);
1702
1703 post_full_gc_dump(gc_timer);
1704
1705 gc_timer->register_gc_end();
1706 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1707 }
1708
1709 return true;
1710 }
1711
1712 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1713 // do_collection() will return whether it succeeded in performing
1714 // the GC. Currently, there is no facility on the
1715 // do_full_collection() API to notify the caller than the collection
1716 // did not succeed (e.g., because it was locked out by the GC
1717 // locker). So, right now, we'll ignore the return value.
1718 bool dummy = do_collection(true, /* explicit_gc */
1719 clear_all_soft_refs,
1720 0 /* word_size */);
1721 }
1722
1723 // This code is mostly copied from TenuredGeneration.
1724 void
1725 G1CollectedHeap::
1726 resize_if_necessary_after_full_collection(size_t word_size) {
1727 // Include the current allocation, if any, and bytes that will be
1728 // pre-allocated to support collections, as "used".
1729 const size_t used_after_gc = used();
1730 const size_t capacity_after_gc = capacity();
1731 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1732
1733 // This is enforced in arguments.cpp.
1734 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1735 "otherwise the code below doesn't make sense");
1736
1737 // We don't have floating point command-line arguments
1738 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1739 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1740 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1741 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1742
1743 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1744 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1745
1746 // We have to be careful here as these two calculations can overflow
1747 // 32-bit size_t's.
1748 double used_after_gc_d = (double) used_after_gc;
1749 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1750 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1751
1752 // Let's make sure that they are both under the max heap size, which
1753 // by default will make them fit into a size_t.
1754 double desired_capacity_upper_bound = (double) max_heap_size;
1755 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1756 desired_capacity_upper_bound);
1757 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1758 desired_capacity_upper_bound);
1759
1760 // We can now safely turn them into size_t's.
1761 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1762 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1763
1764 // This assert only makes sense here, before we adjust them
1765 // with respect to the min and max heap size.
1766 assert(minimum_desired_capacity <= maximum_desired_capacity,
1767 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1768 "maximum_desired_capacity = " SIZE_FORMAT,
1769 minimum_desired_capacity, maximum_desired_capacity));
1770
1771 // Should not be greater than the heap max size. No need to adjust
1772 // it with respect to the heap min size as it's a lower bound (i.e.,
1773 // we'll try to make the capacity larger than it, not smaller).
1774 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1775 // Should not be less than the heap min size. No need to adjust it
1776 // with respect to the heap max size as it's an upper bound (i.e.,
1777 // we'll try to make the capacity smaller than it, not greater).
1778 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1779
1780 if (capacity_after_gc < minimum_desired_capacity) {
1781 // Don't expand unless it's significant
1782 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1783 ergo_verbose4(ErgoHeapSizing,
1784 "attempt heap expansion",
1785 ergo_format_reason("capacity lower than "
1786 "min desired capacity after Full GC")
1787 ergo_format_byte("capacity")
1788 ergo_format_byte("occupancy")
1789 ergo_format_byte_perc("min desired capacity"),
1790 capacity_after_gc, used_after_gc,
1791 minimum_desired_capacity, (double) MinHeapFreeRatio);
1792 expand(expand_bytes);
1793
1794 // No expansion, now see if we want to shrink
1795 } else if (capacity_after_gc > maximum_desired_capacity) {
1796 // Capacity too large, compute shrinking size
1797 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1798 ergo_verbose4(ErgoHeapSizing,
1799 "attempt heap shrinking",
1800 ergo_format_reason("capacity higher than "
1801 "max desired capacity after Full GC")
1802 ergo_format_byte("capacity")
1803 ergo_format_byte("occupancy")
1804 ergo_format_byte_perc("max desired capacity"),
1805 capacity_after_gc, used_after_gc,
1806 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1807 shrink(shrink_bytes);
1808 }
1809 }
1810
1811
1812 HeapWord*
1813 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1814 AllocationContext_t context,
1815 bool* succeeded) {
1816 assert_at_safepoint(true /* should_be_vm_thread */);
1817
1818 *succeeded = true;
1819 // Let's attempt the allocation first.
1820 HeapWord* result =
1821 attempt_allocation_at_safepoint(word_size,
1822 context,
1823 false /* expect_null_mutator_alloc_region */);
1824 if (result != NULL) {
1825 assert(*succeeded, "sanity");
1826 return result;
1827 }
1828
1829 // In a G1 heap, we're supposed to keep allocation from failing by
1830 // incremental pauses. Therefore, at least for now, we'll favor
1831 // expansion over collection. (This might change in the future if we can
1832 // do something smarter than full collection to satisfy a failed alloc.)
1833 result = expand_and_allocate(word_size, context);
1834 if (result != NULL) {
1835 assert(*succeeded, "sanity");
1836 return result;
1837 }
1838
1839 // Expansion didn't work, we'll try to do a Full GC.
1840 bool gc_succeeded = do_collection(false, /* explicit_gc */
1841 false, /* clear_all_soft_refs */
1842 word_size);
1843 if (!gc_succeeded) {
1844 *succeeded = false;
1845 return NULL;
1846 }
1847
1848 // Retry the allocation
1849 result = attempt_allocation_at_safepoint(word_size,
1850 context,
1851 true /* expect_null_mutator_alloc_region */);
1852 if (result != NULL) {
1853 assert(*succeeded, "sanity");
1854 return result;
1855 }
1856
1857 // Then, try a Full GC that will collect all soft references.
1858 gc_succeeded = do_collection(false, /* explicit_gc */
1859 true, /* clear_all_soft_refs */
1860 word_size);
1861 if (!gc_succeeded) {
1862 *succeeded = false;
1863 return NULL;
1864 }
1865
1866 // Retry the allocation once more
1867 result = attempt_allocation_at_safepoint(word_size,
1868 context,
1869 true /* expect_null_mutator_alloc_region */);
1870 if (result != NULL) {
1871 assert(*succeeded, "sanity");
1872 return result;
1873 }
1874
1875 assert(!collector_policy()->should_clear_all_soft_refs(),
1876 "Flag should have been handled and cleared prior to this point");
1877
1878 // What else? We might try synchronous finalization later. If the total
1879 // space available is large enough for the allocation, then a more
1880 // complete compaction phase than we've tried so far might be
1881 // appropriate.
1882 assert(*succeeded, "sanity");
1883 return NULL;
1884 }
1885
1886 // Attempting to expand the heap sufficiently
1887 // to support an allocation of the given "word_size". If
1888 // successful, perform the allocation and return the address of the
1889 // allocated block, or else "NULL".
1890
1891 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1892 assert_at_safepoint(true /* should_be_vm_thread */);
1893
1894 verify_region_sets_optional();
1895
1896 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1897 ergo_verbose1(ErgoHeapSizing,
1898 "attempt heap expansion",
1899 ergo_format_reason("allocation request failed")
1900 ergo_format_byte("allocation request"),
1901 word_size * HeapWordSize);
1902 if (expand(expand_bytes)) {
1903 _hrm.verify_optional();
1904 verify_region_sets_optional();
1905 return attempt_allocation_at_safepoint(word_size,
1906 context,
1907 false /* expect_null_mutator_alloc_region */);
1908 }
1909 return NULL;
1910 }
1911
1912 bool G1CollectedHeap::expand(size_t expand_bytes) {
1913 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1914 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1915 HeapRegion::GrainBytes);
1916 ergo_verbose2(ErgoHeapSizing,
1917 "expand the heap",
1918 ergo_format_byte("requested expansion amount")
1919 ergo_format_byte("attempted expansion amount"),
1920 expand_bytes, aligned_expand_bytes);
1921
1922 if (is_maximal_no_gc()) {
1923 ergo_verbose0(ErgoHeapSizing,
1924 "did not expand the heap",
1925 ergo_format_reason("heap already fully expanded"));
1926 return false;
1927 }
1928
1929 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1930 assert(regions_to_expand > 0, "Must expand by at least one region");
1931
1932 uint expanded_by = _hrm.expand_by(regions_to_expand);
1933
1934 if (expanded_by > 0) {
1935 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1936 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1937 g1_policy()->record_new_heap_size(num_regions());
1938 } else {
1939 ergo_verbose0(ErgoHeapSizing,
1940 "did not expand the heap",
1941 ergo_format_reason("heap expansion operation failed"));
1942 // The expansion of the virtual storage space was unsuccessful.
1943 // Let's see if it was because we ran out of swap.
1944 if (G1ExitOnExpansionFailure &&
1945 _hrm.available() >= regions_to_expand) {
1946 // We had head room...
1947 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1948 }
1949 }
1950 return regions_to_expand > 0;
1951 }
1952
1953 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1954 size_t aligned_shrink_bytes =
1955 ReservedSpace::page_align_size_down(shrink_bytes);
1956 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1957 HeapRegion::GrainBytes);
1958 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1959
1960 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1961 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1962
1963 ergo_verbose3(ErgoHeapSizing,
1964 "shrink the heap",
1965 ergo_format_byte("requested shrinking amount")
1966 ergo_format_byte("aligned shrinking amount")
1967 ergo_format_byte("attempted shrinking amount"),
1968 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1969 if (num_regions_removed > 0) {
1970 g1_policy()->record_new_heap_size(num_regions());
1971 } else {
1972 ergo_verbose0(ErgoHeapSizing,
1973 "did not shrink the heap",
1974 ergo_format_reason("heap shrinking operation failed"));
1975 }
1976 }
1977
1978 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1979 verify_region_sets_optional();
1980
1981 // We should only reach here at the end of a Full GC which means we
1982 // should not not be holding to any GC alloc regions. The method
1983 // below will make sure of that and do any remaining clean up.
1984 _allocator->abandon_gc_alloc_regions();
1985
1986 // Instead of tearing down / rebuilding the free lists here, we
1987 // could instead use the remove_all_pending() method on free_list to
1988 // remove only the ones that we need to remove.
1989 tear_down_region_sets(true /* free_list_only */);
1990 shrink_helper(shrink_bytes);
1991 rebuild_region_sets(true /* free_list_only */);
1992
1993 _hrm.verify_optional();
1994 verify_region_sets_optional();
1995 }
1996
1997 // Public methods.
1998
1999 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
2000 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
2001 #endif // _MSC_VER
2002
2003
2004 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2005 CollectedHeap(),
2006 _g1_policy(policy_),
2007 _dirty_card_queue_set(false),
2008 _into_cset_dirty_card_queue_set(false),
2009 _is_alive_closure_cm(this),
2010 _is_alive_closure_stw(this),
2011 _ref_processor_cm(NULL),
2012 _ref_processor_stw(NULL),
2013 _bot_shared(NULL),
2014 _cg1r(NULL),
2015 _g1mm(NULL),
2016 _refine_cte_cl(NULL),
2017 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2018 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2019 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2020 _humongous_reclaim_candidates(),
2021 _has_humongous_reclaim_candidates(false),
2022 _archive_allocator(NULL),
2023 _free_regions_coming(false),
2024 _young_list(new YoungList(this)),
2025 _gc_time_stamp(0),
2026 _summary_bytes_used(0),
2027 _survivor_evac_stats(YoungPLABSize, PLABWeight),
2028 _old_evac_stats(OldPLABSize, PLABWeight),
2029 _expand_heap_after_alloc_failure(true),
2030 _surviving_young_words(NULL),
2031 _old_marking_cycles_started(0),
2032 _old_marking_cycles_completed(0),
2033 _heap_summary_sent(false),
2034 _in_cset_fast_test(),
2035 _dirty_cards_region_list(NULL),
2036 _worker_cset_start_region(NULL),
2037 _worker_cset_start_region_time_stamp(NULL),
2038 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2039 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2040 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2041 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2042
2043 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2044 /* are_GC_task_threads */true,
2045 /* are_ConcurrentGC_threads */false);
2046 _workers->initialize_workers();
2047
2048 _allocator = G1Allocator::create_allocator(this);
2049 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2050
2051 // Override the default _filler_array_max_size so that no humongous filler
2052 // objects are created.
2053 _filler_array_max_size = _humongous_object_threshold_in_words;
2054
2055 uint n_queues = ParallelGCThreads;
2056 _task_queues = new RefToScanQueueSet(n_queues);
2057
2058 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2059 assert(n_rem_sets > 0, "Invariant.");
2060
2061 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2062 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2063 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2064
2065 for (uint i = 0; i < n_queues; i++) {
2066 RefToScanQueue* q = new RefToScanQueue();
2067 q->initialize();
2068 _task_queues->register_queue(i, q);
2069 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2070 }
2071 clear_cset_start_regions();
2072
2073 // Initialize the G1EvacuationFailureALot counters and flags.
2074 NOT_PRODUCT(reset_evacuation_should_fail();)
2075
2076 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2077 }
2078
2079 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2080 size_t size,
2081 size_t translation_factor) {
2082 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2083 // Allocate a new reserved space, preferring to use large pages.
2084 ReservedSpace rs(size, preferred_page_size);
2085 G1RegionToSpaceMapper* result =
2086 G1RegionToSpaceMapper::create_mapper(rs,
2087 size,
2088 rs.alignment(),
2089 HeapRegion::GrainBytes,
2090 translation_factor,
2091 mtGC);
2092 if (TracePageSizes) {
2093 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2094 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2095 }
2096 return result;
2097 }
2098
2099 jint G1CollectedHeap::initialize() {
2100 CollectedHeap::pre_initialize();
2101 os::enable_vtime();
2102
2103 G1Log::init();
2104
2105 // Necessary to satisfy locking discipline assertions.
2106
2107 MutexLocker x(Heap_lock);
2108
2109 // We have to initialize the printer before committing the heap, as
2110 // it will be used then.
2111 _hr_printer.set_active(G1PrintHeapRegions);
2112
2113 // While there are no constraints in the GC code that HeapWordSize
2114 // be any particular value, there are multiple other areas in the
2115 // system which believe this to be true (e.g. oop->object_size in some
2116 // cases incorrectly returns the size in wordSize units rather than
2117 // HeapWordSize).
2118 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2119
2120 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2121 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2122 size_t heap_alignment = collector_policy()->heap_alignment();
2123
2124 // Ensure that the sizes are properly aligned.
2125 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2126 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2127 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2128
2129 _refine_cte_cl = new RefineCardTableEntryClosure();
2130
2131 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2132
2133 // Reserve the maximum.
2134
2135 // When compressed oops are enabled, the preferred heap base
2136 // is calculated by subtracting the requested size from the
2137 // 32Gb boundary and using the result as the base address for
2138 // heap reservation. If the requested size is not aligned to
2139 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2140 // into the ReservedHeapSpace constructor) then the actual
2141 // base of the reserved heap may end up differing from the
2142 // address that was requested (i.e. the preferred heap base).
2143 // If this happens then we could end up using a non-optimal
2144 // compressed oops mode.
2145
2146 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2147 heap_alignment);
2148
2149 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2150
2151 // Create the barrier set for the entire reserved region.
2152 G1SATBCardTableLoggingModRefBS* bs
2153 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2154 bs->initialize();
2155 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2156 set_barrier_set(bs);
2157
2158 // Also create a G1 rem set.
2159 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2160
2161 // Carve out the G1 part of the heap.
2162
2163 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2164 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2165 G1RegionToSpaceMapper* heap_storage =
2166 G1RegionToSpaceMapper::create_mapper(g1_rs,
2167 g1_rs.size(),
2168 page_size,
2169 HeapRegion::GrainBytes,
2170 1,
2171 mtJavaHeap);
2172 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2173 max_byte_size, page_size,
2174 heap_rs.base(),
2175 heap_rs.size());
2176 heap_storage->set_mapping_changed_listener(&_listener);
2177
2178 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2179 G1RegionToSpaceMapper* bot_storage =
2180 create_aux_memory_mapper("Block offset table",
2181 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2182 G1BlockOffsetSharedArray::heap_map_factor());
2183
2184 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2185 G1RegionToSpaceMapper* cardtable_storage =
2186 create_aux_memory_mapper("Card table",
2187 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2188 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2189
2190 G1RegionToSpaceMapper* card_counts_storage =
2191 create_aux_memory_mapper("Card counts table",
2192 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2193 G1CardCounts::heap_map_factor());
2194
2195 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2196 G1RegionToSpaceMapper* prev_bitmap_storage =
2197 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2198 G1RegionToSpaceMapper* next_bitmap_storage =
2199 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2200
2201 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2202 g1_barrier_set()->initialize(cardtable_storage);
2203 // Do later initialization work for concurrent refinement.
2204 _cg1r->init(card_counts_storage);
2205
2206 // 6843694 - ensure that the maximum region index can fit
2207 // in the remembered set structures.
2208 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2209 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2210
2211 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2212 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2213 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2214 "too many cards per region");
2215
2216 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2217
2218 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2219
2220 {
2221 HeapWord* start = _hrm.reserved().start();
2222 HeapWord* end = _hrm.reserved().end();
2223 size_t granularity = HeapRegion::GrainBytes;
2224
2225 _in_cset_fast_test.initialize(start, end, granularity);
2226 _humongous_reclaim_candidates.initialize(start, end, granularity);
2227 }
2228
2229 // Create the ConcurrentMark data structure and thread.
2230 // (Must do this late, so that "max_regions" is defined.)
2231 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2232 if (_cm == NULL || !_cm->completed_initialization()) {
2233 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2234 return JNI_ENOMEM;
2235 }
2236 _cmThread = _cm->cmThread();
2237
2238 // Initialize the from_card cache structure of HeapRegionRemSet.
2239 HeapRegionRemSet::init_heap(max_regions());
2240
2241 // Now expand into the initial heap size.
2242 if (!expand(init_byte_size)) {
2243 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2244 return JNI_ENOMEM;
2245 }
2246
2247 // Perform any initialization actions delegated to the policy.
2248 g1_policy()->init();
2249
2250 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2251 SATB_Q_FL_lock,
2252 G1SATBProcessCompletedThreshold,
2253 Shared_SATB_Q_lock);
2254
2255 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2256 DirtyCardQ_CBL_mon,
2257 DirtyCardQ_FL_lock,
2258 concurrent_g1_refine()->yellow_zone(),
2259 concurrent_g1_refine()->red_zone(),
2260 Shared_DirtyCardQ_lock);
2261
2262 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2263 DirtyCardQ_CBL_mon,
2264 DirtyCardQ_FL_lock,
2265 -1, // never trigger processing
2266 -1, // no limit on length
2267 Shared_DirtyCardQ_lock,
2268 &JavaThread::dirty_card_queue_set());
2269
2270 // Initialize the card queue set used to hold cards containing
2271 // references into the collection set.
2272 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2273 DirtyCardQ_CBL_mon,
2274 DirtyCardQ_FL_lock,
2275 -1, // never trigger processing
2276 -1, // no limit on length
2277 Shared_DirtyCardQ_lock,
2278 &JavaThread::dirty_card_queue_set());
2279
2280 // Here we allocate the dummy HeapRegion that is required by the
2281 // G1AllocRegion class.
2282 HeapRegion* dummy_region = _hrm.get_dummy_region();
2283
2284 // We'll re-use the same region whether the alloc region will
2285 // require BOT updates or not and, if it doesn't, then a non-young
2286 // region will complain that it cannot support allocations without
2287 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2288 dummy_region->set_eden();
2289 // Make sure it's full.
2290 dummy_region->set_top(dummy_region->end());
2291 G1AllocRegion::setup(this, dummy_region);
2292
2293 _allocator->init_mutator_alloc_region();
2294
2295 // Do create of the monitoring and management support so that
2296 // values in the heap have been properly initialized.
2297 _g1mm = new G1MonitoringSupport(this);
2298
2299 G1StringDedup::initialize();
2300
2301 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2302 for (uint i = 0; i < ParallelGCThreads; i++) {
2303 new (&_preserved_objs[i]) OopAndMarkOopStack();
2304 }
2305
2306 return JNI_OK;
2307 }
2308
2309 void G1CollectedHeap::stop() {
2310 // Stop all concurrent threads. We do this to make sure these threads
2311 // do not continue to execute and access resources (e.g. gclog_or_tty)
2312 // that are destroyed during shutdown.
2313 _cg1r->stop();
2314 _cmThread->stop();
2315 if (G1StringDedup::is_enabled()) {
2316 G1StringDedup::stop();
2317 }
2318 }
2319
2320 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2321 return HeapRegion::max_region_size();
2322 }
2323
2324 void G1CollectedHeap::post_initialize() {
2325 CollectedHeap::post_initialize();
2326 ref_processing_init();
2327 }
2328
2329 void G1CollectedHeap::ref_processing_init() {
2330 // Reference processing in G1 currently works as follows:
2331 //
2332 // * There are two reference processor instances. One is
2333 // used to record and process discovered references
2334 // during concurrent marking; the other is used to
2335 // record and process references during STW pauses
2336 // (both full and incremental).
2337 // * Both ref processors need to 'span' the entire heap as
2338 // the regions in the collection set may be dotted around.
2339 //
2340 // * For the concurrent marking ref processor:
2341 // * Reference discovery is enabled at initial marking.
2342 // * Reference discovery is disabled and the discovered
2343 // references processed etc during remarking.
2344 // * Reference discovery is MT (see below).
2345 // * Reference discovery requires a barrier (see below).
2346 // * Reference processing may or may not be MT
2347 // (depending on the value of ParallelRefProcEnabled
2348 // and ParallelGCThreads).
2349 // * A full GC disables reference discovery by the CM
2350 // ref processor and abandons any entries on it's
2351 // discovered lists.
2352 //
2353 // * For the STW processor:
2354 // * Non MT discovery is enabled at the start of a full GC.
2355 // * Processing and enqueueing during a full GC is non-MT.
2356 // * During a full GC, references are processed after marking.
2357 //
2358 // * Discovery (may or may not be MT) is enabled at the start
2359 // of an incremental evacuation pause.
2360 // * References are processed near the end of a STW evacuation pause.
2361 // * For both types of GC:
2362 // * Discovery is atomic - i.e. not concurrent.
2363 // * Reference discovery will not need a barrier.
2364
2365 MemRegion mr = reserved_region();
2366
2367 // Concurrent Mark ref processor
2368 _ref_processor_cm =
2369 new ReferenceProcessor(mr, // span
2370 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2371 // mt processing
2372 ParallelGCThreads,
2373 // degree of mt processing
2374 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2375 // mt discovery
2376 MAX2(ParallelGCThreads, ConcGCThreads),
2377 // degree of mt discovery
2378 false,
2379 // Reference discovery is not atomic
2380 &_is_alive_closure_cm);
2381 // is alive closure
2382 // (for efficiency/performance)
2383
2384 // STW ref processor
2385 _ref_processor_stw =
2386 new ReferenceProcessor(mr, // span
2387 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2388 // mt processing
2389 ParallelGCThreads,
2390 // degree of mt processing
2391 (ParallelGCThreads > 1),
2392 // mt discovery
2393 ParallelGCThreads,
2394 // degree of mt discovery
2395 true,
2396 // Reference discovery is atomic
2397 &_is_alive_closure_stw);
2398 // is alive closure
2399 // (for efficiency/performance)
2400 }
2401
2402 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2403 return g1_policy();
2404 }
2405
2406 size_t G1CollectedHeap::capacity() const {
2407 return _hrm.length() * HeapRegion::GrainBytes;
2408 }
2409
2410 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2411 assert(!hr->is_continues_humongous(), "pre-condition");
2412 hr->reset_gc_time_stamp();
2413 if (hr->is_starts_humongous()) {
2414 uint first_index = hr->hrm_index() + 1;
2415 uint last_index = hr->last_hc_index();
2416 for (uint i = first_index; i < last_index; i += 1) {
2417 HeapRegion* chr = region_at(i);
2418 assert(chr->is_continues_humongous(), "sanity");
2419 chr->reset_gc_time_stamp();
2420 }
2421 }
2422 }
2423
2424 #ifndef PRODUCT
2425
2426 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2427 private:
2428 unsigned _gc_time_stamp;
2429 bool _failures;
2430
2431 public:
2432 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2433 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2434
2435 virtual bool doHeapRegion(HeapRegion* hr) {
2436 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2437 if (_gc_time_stamp != region_gc_time_stamp) {
2438 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2439 "expected %d", HR_FORMAT_PARAMS(hr),
2440 region_gc_time_stamp, _gc_time_stamp);
2441 _failures = true;
2442 }
2443 return false;
2444 }
2445
2446 bool failures() { return _failures; }
2447 };
2448
2449 void G1CollectedHeap::check_gc_time_stamps() {
2450 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2451 heap_region_iterate(&cl);
2452 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2453 }
2454 #endif // PRODUCT
2455
2456 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2457 DirtyCardQueue* into_cset_dcq,
2458 bool concurrent,
2459 uint worker_i) {
2460 // Clean cards in the hot card cache
2461 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2462 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2463
2464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2465 size_t n_completed_buffers = 0;
2466 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2467 n_completed_buffers++;
2468 }
2469 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2470 dcqs.clear_n_completed_buffers();
2471 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2472 }
2473
2474 // Computes the sum of the storage used by the various regions.
2475 size_t G1CollectedHeap::used() const {
2476 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2477 if (_archive_allocator != NULL) {
2478 result += _archive_allocator->used();
2479 }
2480 return result;
2481 }
2482
2483 size_t G1CollectedHeap::used_unlocked() const {
2484 return _summary_bytes_used;
2485 }
2486
2487 class SumUsedClosure: public HeapRegionClosure {
2488 size_t _used;
2489 public:
2490 SumUsedClosure() : _used(0) {}
2491 bool doHeapRegion(HeapRegion* r) {
2492 if (!r->is_continues_humongous()) {
2493 _used += r->used();
2494 }
2495 return false;
2496 }
2497 size_t result() { return _used; }
2498 };
2499
2500 size_t G1CollectedHeap::recalculate_used() const {
2501 double recalculate_used_start = os::elapsedTime();
2502
2503 SumUsedClosure blk;
2504 heap_region_iterate(&blk);
2505
2506 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2507 return blk.result();
2508 }
2509
2510 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2511 switch (cause) {
2512 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2513 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2514 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2515 case GCCause::_g1_humongous_allocation: return true;
2516 case GCCause::_update_allocation_context_stats_inc: return true;
2517 case GCCause::_wb_conc_mark: return true;
2518 default: return false;
2519 }
2520 }
2521
2522 #ifndef PRODUCT
2523 void G1CollectedHeap::allocate_dummy_regions() {
2524 // Let's fill up most of the region
2525 size_t word_size = HeapRegion::GrainWords - 1024;
2526 // And as a result the region we'll allocate will be humongous.
2527 guarantee(is_humongous(word_size), "sanity");
2528
2529 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2530 // Let's use the existing mechanism for the allocation
2531 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2532 AllocationContext::system());
2533 if (dummy_obj != NULL) {
2534 MemRegion mr(dummy_obj, word_size);
2535 CollectedHeap::fill_with_object(mr);
2536 } else {
2537 // If we can't allocate once, we probably cannot allocate
2538 // again. Let's get out of the loop.
2539 break;
2540 }
2541 }
2542 }
2543 #endif // !PRODUCT
2544
2545 void G1CollectedHeap::increment_old_marking_cycles_started() {
2546 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2547 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2548 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2549 _old_marking_cycles_started, _old_marking_cycles_completed));
2550
2551 _old_marking_cycles_started++;
2552 }
2553
2554 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2555 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2556
2557 // We assume that if concurrent == true, then the caller is a
2558 // concurrent thread that was joined the Suspendible Thread
2559 // Set. If there's ever a cheap way to check this, we should add an
2560 // assert here.
2561
2562 // Given that this method is called at the end of a Full GC or of a
2563 // concurrent cycle, and those can be nested (i.e., a Full GC can
2564 // interrupt a concurrent cycle), the number of full collections
2565 // completed should be either one (in the case where there was no
2566 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2567 // behind the number of full collections started.
2568
2569 // This is the case for the inner caller, i.e. a Full GC.
2570 assert(concurrent ||
2571 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2572 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2573 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2574 "is inconsistent with _old_marking_cycles_completed = %u",
2575 _old_marking_cycles_started, _old_marking_cycles_completed));
2576
2577 // This is the case for the outer caller, i.e. the concurrent cycle.
2578 assert(!concurrent ||
2579 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2580 err_msg("for outer caller (concurrent cycle): "
2581 "_old_marking_cycles_started = %u "
2582 "is inconsistent with _old_marking_cycles_completed = %u",
2583 _old_marking_cycles_started, _old_marking_cycles_completed));
2584
2585 _old_marking_cycles_completed += 1;
2586
2587 // We need to clear the "in_progress" flag in the CM thread before
2588 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2589 // is set) so that if a waiter requests another System.gc() it doesn't
2590 // incorrectly see that a marking cycle is still in progress.
2591 if (concurrent) {
2592 _cmThread->set_idle();
2593 }
2594
2595 // This notify_all() will ensure that a thread that called
2596 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2597 // and it's waiting for a full GC to finish will be woken up. It is
2598 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2599 FullGCCount_lock->notify_all();
2600 }
2601
2602 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2603 collector_state()->set_concurrent_cycle_started(true);
2604 _gc_timer_cm->register_gc_start(start_time);
2605
2606 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2607 trace_heap_before_gc(_gc_tracer_cm);
2608 }
2609
2610 void G1CollectedHeap::register_concurrent_cycle_end() {
2611 if (collector_state()->concurrent_cycle_started()) {
2612 if (_cm->has_aborted()) {
2613 _gc_tracer_cm->report_concurrent_mode_failure();
2614 }
2615
2616 _gc_timer_cm->register_gc_end();
2617 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2618
2619 // Clear state variables to prepare for the next concurrent cycle.
2620 collector_state()->set_concurrent_cycle_started(false);
2621 _heap_summary_sent = false;
2622 }
2623 }
2624
2625 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2626 if (collector_state()->concurrent_cycle_started()) {
2627 // This function can be called when:
2628 // the cleanup pause is run
2629 // the concurrent cycle is aborted before the cleanup pause.
2630 // the concurrent cycle is aborted after the cleanup pause,
2631 // but before the concurrent cycle end has been registered.
2632 // Make sure that we only send the heap information once.
2633 if (!_heap_summary_sent) {
2634 trace_heap_after_gc(_gc_tracer_cm);
2635 _heap_summary_sent = true;
2636 }
2637 }
2638 }
2639
2640 void G1CollectedHeap::collect(GCCause::Cause cause) {
2641 assert_heap_not_locked();
2642
2643 uint gc_count_before;
2644 uint old_marking_count_before;
2645 uint full_gc_count_before;
2646 bool retry_gc;
2647
2648 do {
2649 retry_gc = false;
2650
2651 {
2652 MutexLocker ml(Heap_lock);
2653
2654 // Read the GC count while holding the Heap_lock
2655 gc_count_before = total_collections();
2656 full_gc_count_before = total_full_collections();
2657 old_marking_count_before = _old_marking_cycles_started;
2658 }
2659
2660 if (should_do_concurrent_full_gc(cause)) {
2661 // Schedule an initial-mark evacuation pause that will start a
2662 // concurrent cycle. We're setting word_size to 0 which means that
2663 // we are not requesting a post-GC allocation.
2664 VM_G1IncCollectionPause op(gc_count_before,
2665 0, /* word_size */
2666 true, /* should_initiate_conc_mark */
2667 g1_policy()->max_pause_time_ms(),
2668 cause);
2669 op.set_allocation_context(AllocationContext::current());
2670
2671 VMThread::execute(&op);
2672 if (!op.pause_succeeded()) {
2673 if (old_marking_count_before == _old_marking_cycles_started) {
2674 retry_gc = op.should_retry_gc();
2675 } else {
2676 // A Full GC happened while we were trying to schedule the
2677 // initial-mark GC. No point in starting a new cycle given
2678 // that the whole heap was collected anyway.
2679 }
2680
2681 if (retry_gc) {
2682 if (GC_locker::is_active_and_needs_gc()) {
2683 GC_locker::stall_until_clear();
2684 }
2685 }
2686 }
2687 } else {
2688 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2689 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2690
2691 // Schedule a standard evacuation pause. We're setting word_size
2692 // to 0 which means that we are not requesting a post-GC allocation.
2693 VM_G1IncCollectionPause op(gc_count_before,
2694 0, /* word_size */
2695 false, /* should_initiate_conc_mark */
2696 g1_policy()->max_pause_time_ms(),
2697 cause);
2698 VMThread::execute(&op);
2699 } else {
2700 // Schedule a Full GC.
2701 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2702 VMThread::execute(&op);
2703 }
2704 }
2705 } while (retry_gc);
2706 }
2707
2708 bool G1CollectedHeap::is_in(const void* p) const {
2709 if (_hrm.reserved().contains(p)) {
2710 // Given that we know that p is in the reserved space,
2711 // heap_region_containing_raw() should successfully
2712 // return the containing region.
2713 HeapRegion* hr = heap_region_containing_raw(p);
2714 return hr->is_in(p);
2715 } else {
2716 return false;
2717 }
2718 }
2719
2720 #ifdef ASSERT
2721 bool G1CollectedHeap::is_in_exact(const void* p) const {
2722 bool contains = reserved_region().contains(p);
2723 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2724 if (contains && available) {
2725 return true;
2726 } else {
2727 return false;
2728 }
2729 }
2730 #endif
2731
2732 bool G1CollectedHeap::obj_in_cs(oop obj) {
2733 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2734 return r != NULL && r->in_collection_set();
2735 }
2736
2737 // Iteration functions.
2738
2739 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2740
2741 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2742 ExtendedOopClosure* _cl;
2743 public:
2744 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2745 bool doHeapRegion(HeapRegion* r) {
2746 if (!r->is_continues_humongous()) {
2747 r->oop_iterate(_cl);
2748 }
2749 return false;
2750 }
2751 };
2752
2753 // Iterates an ObjectClosure over all objects within a HeapRegion.
2754
2755 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2756 ObjectClosure* _cl;
2757 public:
2758 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2759 bool doHeapRegion(HeapRegion* r) {
2760 if (!r->is_continues_humongous()) {
2761 r->object_iterate(_cl);
2762 }
2763 return false;
2764 }
2765 };
2766
2767 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2768 IterateObjectClosureRegionClosure blk(cl);
2769 heap_region_iterate(&blk);
2770 }
2771
2772 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2773 _hrm.iterate(cl);
2774 }
2775
2776 void
2777 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2778 uint worker_id,
2779 HeapRegionClaimer *hrclaimer,
2780 bool concurrent) const {
2781 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2782 }
2783
2784 // Clear the cached CSet starting regions and (more importantly)
2785 // the time stamps. Called when we reset the GC time stamp.
2786 void G1CollectedHeap::clear_cset_start_regions() {
2787 assert(_worker_cset_start_region != NULL, "sanity");
2788 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2789
2790 for (uint i = 0; i < ParallelGCThreads; i++) {
2791 _worker_cset_start_region[i] = NULL;
2792 _worker_cset_start_region_time_stamp[i] = 0;
2793 }
2794 }
2795
2796 // Given the id of a worker, obtain or calculate a suitable
2797 // starting region for iterating over the current collection set.
2798 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2799 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2800
2801 HeapRegion* result = NULL;
2802 unsigned gc_time_stamp = get_gc_time_stamp();
2803
2804 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2805 // Cached starting region for current worker was set
2806 // during the current pause - so it's valid.
2807 // Note: the cached starting heap region may be NULL
2808 // (when the collection set is empty).
2809 result = _worker_cset_start_region[worker_i];
2810 assert(result == NULL || result->in_collection_set(), "sanity");
2811 return result;
2812 }
2813
2814 // The cached entry was not valid so let's calculate
2815 // a suitable starting heap region for this worker.
2816
2817 // We want the parallel threads to start their collection
2818 // set iteration at different collection set regions to
2819 // avoid contention.
2820 // If we have:
2821 // n collection set regions
2822 // p threads
2823 // Then thread t will start at region floor ((t * n) / p)
2824
2825 result = g1_policy()->collection_set();
2826 uint cs_size = g1_policy()->cset_region_length();
2827 uint active_workers = workers()->active_workers();
2828
2829 uint end_ind = (cs_size * worker_i) / active_workers;
2830 uint start_ind = 0;
2831
2832 if (worker_i > 0 &&
2833 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2834 // Previous workers starting region is valid
2835 // so let's iterate from there
2836 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2837 result = _worker_cset_start_region[worker_i - 1];
2838 }
2839
2840 for (uint i = start_ind; i < end_ind; i++) {
2841 result = result->next_in_collection_set();
2842 }
2843
2844 // Note: the calculated starting heap region may be NULL
2845 // (when the collection set is empty).
2846 assert(result == NULL || result->in_collection_set(), "sanity");
2847 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2848 "should be updated only once per pause");
2849 _worker_cset_start_region[worker_i] = result;
2850 OrderAccess::storestore();
2851 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2852 return result;
2853 }
2854
2855 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2856 HeapRegion* r = g1_policy()->collection_set();
2857 while (r != NULL) {
2858 HeapRegion* next = r->next_in_collection_set();
2859 if (cl->doHeapRegion(r)) {
2860 cl->incomplete();
2861 return;
2862 }
2863 r = next;
2864 }
2865 }
2866
2867 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2868 HeapRegionClosure *cl) {
2869 if (r == NULL) {
2870 // The CSet is empty so there's nothing to do.
2871 return;
2872 }
2873
2874 assert(r->in_collection_set(),
2875 "Start region must be a member of the collection set.");
2876 HeapRegion* cur = r;
2877 while (cur != NULL) {
2878 HeapRegion* next = cur->next_in_collection_set();
2879 if (cl->doHeapRegion(cur) && false) {
2880 cl->incomplete();
2881 return;
2882 }
2883 cur = next;
2884 }
2885 cur = g1_policy()->collection_set();
2886 while (cur != r) {
2887 HeapRegion* next = cur->next_in_collection_set();
2888 if (cl->doHeapRegion(cur) && false) {
2889 cl->incomplete();
2890 return;
2891 }
2892 cur = next;
2893 }
2894 }
2895
2896 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2897 HeapRegion* result = _hrm.next_region_in_heap(from);
2898 while (result != NULL && result->is_pinned()) {
2899 result = _hrm.next_region_in_heap(result);
2900 }
2901 return result;
2902 }
2903
2904 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2905 HeapRegion* hr = heap_region_containing(addr);
2906 return hr->block_start(addr);
2907 }
2908
2909 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2910 HeapRegion* hr = heap_region_containing(addr);
2911 return hr->block_size(addr);
2912 }
2913
2914 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2915 HeapRegion* hr = heap_region_containing(addr);
2916 return hr->block_is_obj(addr);
2917 }
2918
2919 bool G1CollectedHeap::supports_tlab_allocation() const {
2920 return true;
2921 }
2922
2923 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2924 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2925 }
2926
2927 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2928 return young_list()->eden_used_bytes();
2929 }
2930
2931 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2932 // must be equal to the humongous object limit.
2933 size_t G1CollectedHeap::max_tlab_size() const {
2934 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2935 }
2936
2937 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2938 AllocationContext_t context = AllocationContext::current();
2939 return _allocator->unsafe_max_tlab_alloc(context);
2940 }
2941
2942 size_t G1CollectedHeap::max_capacity() const {
2943 return _hrm.reserved().byte_size();
2944 }
2945
2946 jlong G1CollectedHeap::millis_since_last_gc() {
2947 // assert(false, "NYI");
2948 return 0;
2949 }
2950
2951 void G1CollectedHeap::prepare_for_verify() {
2952 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2953 ensure_parsability(false);
2954 }
2955 g1_rem_set()->prepare_for_verify();
2956 }
2957
2958 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2959 VerifyOption vo) {
2960 switch (vo) {
2961 case VerifyOption_G1UsePrevMarking:
2962 return hr->obj_allocated_since_prev_marking(obj);
2963 case VerifyOption_G1UseNextMarking:
2964 return hr->obj_allocated_since_next_marking(obj);
2965 case VerifyOption_G1UseMarkWord:
2966 return false;
2967 default:
2968 ShouldNotReachHere();
2969 }
2970 return false; // keep some compilers happy
2971 }
2972
2973 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2974 switch (vo) {
2975 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2976 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2977 case VerifyOption_G1UseMarkWord: return NULL;
2978 default: ShouldNotReachHere();
2979 }
2980 return NULL; // keep some compilers happy
2981 }
2982
2983 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2984 switch (vo) {
2985 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2986 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2987 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2988 default: ShouldNotReachHere();
2989 }
2990 return false; // keep some compilers happy
2991 }
2992
2993 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2994 switch (vo) {
2995 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2996 case VerifyOption_G1UseNextMarking: return "NTAMS";
2997 case VerifyOption_G1UseMarkWord: return "NONE";
2998 default: ShouldNotReachHere();
2999 }
3000 return NULL; // keep some compilers happy
3001 }
3002
3003 class VerifyRootsClosure: public OopClosure {
3004 private:
3005 G1CollectedHeap* _g1h;
3006 VerifyOption _vo;
3007 bool _failures;
3008 public:
3009 // _vo == UsePrevMarking -> use "prev" marking information,
3010 // _vo == UseNextMarking -> use "next" marking information,
3011 // _vo == UseMarkWord -> use mark word from object header.
3012 VerifyRootsClosure(VerifyOption vo) :
3013 _g1h(G1CollectedHeap::heap()),
3014 _vo(vo),
3015 _failures(false) { }
3016
3017 bool failures() { return _failures; }
3018
3019 template <class T> void do_oop_nv(T* p) {
3020 T heap_oop = oopDesc::load_heap_oop(p);
3021 if (!oopDesc::is_null(heap_oop)) {
3022 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3023 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3024 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3025 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3026 if (_vo == VerifyOption_G1UseMarkWord) {
3027 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3028 }
3029 obj->print_on(gclog_or_tty);
3030 _failures = true;
3031 }
3032 }
3033 }
3034
3035 void do_oop(oop* p) { do_oop_nv(p); }
3036 void do_oop(narrowOop* p) { do_oop_nv(p); }
3037 };
3038
3039 class G1VerifyCodeRootOopClosure: public OopClosure {
3040 G1CollectedHeap* _g1h;
3041 OopClosure* _root_cl;
3042 nmethod* _nm;
3043 VerifyOption _vo;
3044 bool _failures;
3045
3046 template <class T> void do_oop_work(T* p) {
3047 // First verify that this root is live
3048 _root_cl->do_oop(p);
3049
3050 if (!G1VerifyHeapRegionCodeRoots) {
3051 // We're not verifying the code roots attached to heap region.
3052 return;
3053 }
3054
3055 // Don't check the code roots during marking verification in a full GC
3056 if (_vo == VerifyOption_G1UseMarkWord) {
3057 return;
3058 }
3059
3060 // Now verify that the current nmethod (which contains p) is
3061 // in the code root list of the heap region containing the
3062 // object referenced by p.
3063
3064 T heap_oop = oopDesc::load_heap_oop(p);
3065 if (!oopDesc::is_null(heap_oop)) {
3066 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3067
3068 // Now fetch the region containing the object
3069 HeapRegion* hr = _g1h->heap_region_containing(obj);
3070 HeapRegionRemSet* hrrs = hr->rem_set();
3071 // Verify that the strong code root list for this region
3072 // contains the nmethod
3073 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3074 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3075 "from nmethod " PTR_FORMAT " not in strong "
3076 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3077 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3078 _failures = true;
3079 }
3080 }
3081 }
3082
3083 public:
3084 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3085 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3086
3087 void do_oop(oop* p) { do_oop_work(p); }
3088 void do_oop(narrowOop* p) { do_oop_work(p); }
3089
3090 void set_nmethod(nmethod* nm) { _nm = nm; }
3091 bool failures() { return _failures; }
3092 };
3093
3094 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3095 G1VerifyCodeRootOopClosure* _oop_cl;
3096
3097 public:
3098 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3099 _oop_cl(oop_cl) {}
3100
3101 void do_code_blob(CodeBlob* cb) {
3102 nmethod* nm = cb->as_nmethod_or_null();
3103 if (nm != NULL) {
3104 _oop_cl->set_nmethod(nm);
3105 nm->oops_do(_oop_cl);
3106 }
3107 }
3108 };
3109
3110 class YoungRefCounterClosure : public OopClosure {
3111 G1CollectedHeap* _g1h;
3112 int _count;
3113 public:
3114 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3115 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3116 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3117
3118 int count() { return _count; }
3119 void reset_count() { _count = 0; };
3120 };
3121
3122 class VerifyKlassClosure: public KlassClosure {
3123 YoungRefCounterClosure _young_ref_counter_closure;
3124 OopClosure *_oop_closure;
3125 public:
3126 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3127 void do_klass(Klass* k) {
3128 k->oops_do(_oop_closure);
3129
3130 _young_ref_counter_closure.reset_count();
3131 k->oops_do(&_young_ref_counter_closure);
3132 if (_young_ref_counter_closure.count() > 0) {
3133 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3134 }
3135 }
3136 };
3137
3138 class VerifyLivenessOopClosure: public OopClosure {
3139 G1CollectedHeap* _g1h;
3140 VerifyOption _vo;
3141 public:
3142 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3143 _g1h(g1h), _vo(vo)
3144 { }
3145 void do_oop(narrowOop *p) { do_oop_work(p); }
3146 void do_oop( oop *p) { do_oop_work(p); }
3147
3148 template <class T> void do_oop_work(T *p) {
3149 oop obj = oopDesc::load_decode_heap_oop(p);
3150 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3151 "Dead object referenced by a not dead object");
3152 }
3153 };
3154
3155 class VerifyObjsInRegionClosure: public ObjectClosure {
3156 private:
3157 G1CollectedHeap* _g1h;
3158 size_t _live_bytes;
3159 HeapRegion *_hr;
3160 VerifyOption _vo;
3161 public:
3162 // _vo == UsePrevMarking -> use "prev" marking information,
3163 // _vo == UseNextMarking -> use "next" marking information,
3164 // _vo == UseMarkWord -> use mark word from object header.
3165 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3166 : _live_bytes(0), _hr(hr), _vo(vo) {
3167 _g1h = G1CollectedHeap::heap();
3168 }
3169 void do_object(oop o) {
3170 VerifyLivenessOopClosure isLive(_g1h, _vo);
3171 assert(o != NULL, "Huh?");
3172 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3173 // If the object is alive according to the mark word,
3174 // then verify that the marking information agrees.
3175 // Note we can't verify the contra-positive of the
3176 // above: if the object is dead (according to the mark
3177 // word), it may not be marked, or may have been marked
3178 // but has since became dead, or may have been allocated
3179 // since the last marking.
3180 if (_vo == VerifyOption_G1UseMarkWord) {
3181 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3182 }
3183
3184 o->oop_iterate_no_header(&isLive);
3185 if (!_hr->obj_allocated_since_prev_marking(o)) {
3186 size_t obj_size = o->size(); // Make sure we don't overflow
3187 _live_bytes += (obj_size * HeapWordSize);
3188 }
3189 }
3190 }
3191 size_t live_bytes() { return _live_bytes; }
3192 };
3193
3194 class VerifyArchiveOopClosure: public OopClosure {
3195 public:
3196 VerifyArchiveOopClosure(HeapRegion *hr) { }
3197 void do_oop(narrowOop *p) { do_oop_work(p); }
3198 void do_oop( oop *p) { do_oop_work(p); }
3199
3200 template <class T> void do_oop_work(T *p) {
3201 oop obj = oopDesc::load_decode_heap_oop(p);
3202 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3203 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3204 p2i(p), p2i(obj)));
3205 }
3206 };
3207
3208 class VerifyArchiveRegionClosure: public ObjectClosure {
3209 public:
3210 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3211 // Verify that all object pointers are to archive regions.
3212 void do_object(oop o) {
3213 VerifyArchiveOopClosure checkOop(NULL);
3214 assert(o != NULL, "Should not be here for NULL oops");
3215 o->oop_iterate_no_header(&checkOop);
3216 }
3217 };
3218
3219 class VerifyRegionClosure: public HeapRegionClosure {
3220 private:
3221 bool _par;
3222 VerifyOption _vo;
3223 bool _failures;
3224 public:
3225 // _vo == UsePrevMarking -> use "prev" marking information,
3226 // _vo == UseNextMarking -> use "next" marking information,
3227 // _vo == UseMarkWord -> use mark word from object header.
3228 VerifyRegionClosure(bool par, VerifyOption vo)
3229 : _par(par),
3230 _vo(vo),
3231 _failures(false) {}
3232
3233 bool failures() {
3234 return _failures;
3235 }
3236
3237 bool doHeapRegion(HeapRegion* r) {
3238 // For archive regions, verify there are no heap pointers to
3239 // non-pinned regions. For all others, verify liveness info.
3240 if (r->is_archive()) {
3241 VerifyArchiveRegionClosure verify_oop_pointers(r);
3242 r->object_iterate(&verify_oop_pointers);
3243 return true;
3244 }
3245 if (!r->is_continues_humongous()) {
3246 bool failures = false;
3247 r->verify(_vo, &failures);
3248 if (failures) {
3249 _failures = true;
3250 } else {
3251 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3252 r->object_iterate(¬_dead_yet_cl);
3253 if (_vo != VerifyOption_G1UseNextMarking) {
3254 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3255 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3256 "max_live_bytes " SIZE_FORMAT " "
3257 "< calculated " SIZE_FORMAT,
3258 p2i(r->bottom()), p2i(r->end()),
3259 r->max_live_bytes(),
3260 not_dead_yet_cl.live_bytes());
3261 _failures = true;
3262 }
3263 } else {
3264 // When vo == UseNextMarking we cannot currently do a sanity
3265 // check on the live bytes as the calculation has not been
3266 // finalized yet.
3267 }
3268 }
3269 }
3270 return false; // stop the region iteration if we hit a failure
3271 }
3272 };
3273
3274 // This is the task used for parallel verification of the heap regions
3275
3276 class G1ParVerifyTask: public AbstractGangTask {
3277 private:
3278 G1CollectedHeap* _g1h;
3279 VerifyOption _vo;
3280 bool _failures;
3281 HeapRegionClaimer _hrclaimer;
3282
3283 public:
3284 // _vo == UsePrevMarking -> use "prev" marking information,
3285 // _vo == UseNextMarking -> use "next" marking information,
3286 // _vo == UseMarkWord -> use mark word from object header.
3287 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3288 AbstractGangTask("Parallel verify task"),
3289 _g1h(g1h),
3290 _vo(vo),
3291 _failures(false),
3292 _hrclaimer(g1h->workers()->active_workers()) {}
3293
3294 bool failures() {
3295 return _failures;
3296 }
3297
3298 void work(uint worker_id) {
3299 HandleMark hm;
3300 VerifyRegionClosure blk(true, _vo);
3301 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3302 if (blk.failures()) {
3303 _failures = true;
3304 }
3305 }
3306 };
3307
3308 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3309 if (SafepointSynchronize::is_at_safepoint()) {
3310 assert(Thread::current()->is_VM_thread(),
3311 "Expected to be executed serially by the VM thread at this point");
3312
3313 if (!silent) { gclog_or_tty->print("Roots "); }
3314 VerifyRootsClosure rootsCl(vo);
3315 VerifyKlassClosure klassCl(this, &rootsCl);
3316 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3317
3318 // We apply the relevant closures to all the oops in the
3319 // system dictionary, class loader data graph, the string table
3320 // and the nmethods in the code cache.
3321 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3322 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3323
3324 {
3325 G1RootProcessor root_processor(this, 1);
3326 root_processor.process_all_roots(&rootsCl,
3327 &cldCl,
3328 &blobsCl);
3329 }
3330
3331 bool failures = rootsCl.failures() || codeRootsCl.failures();
3332
3333 if (vo != VerifyOption_G1UseMarkWord) {
3334 // If we're verifying during a full GC then the region sets
3335 // will have been torn down at the start of the GC. Therefore
3336 // verifying the region sets will fail. So we only verify
3337 // the region sets when not in a full GC.
3338 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3339 verify_region_sets();
3340 }
3341
3342 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3343 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3344
3345 G1ParVerifyTask task(this, vo);
3346 workers()->run_task(&task);
3347 if (task.failures()) {
3348 failures = true;
3349 }
3350
3351 } else {
3352 VerifyRegionClosure blk(false, vo);
3353 heap_region_iterate(&blk);
3354 if (blk.failures()) {
3355 failures = true;
3356 }
3357 }
3358
3359 if (G1StringDedup::is_enabled()) {
3360 if (!silent) gclog_or_tty->print("StrDedup ");
3361 G1StringDedup::verify();
3362 }
3363
3364 if (failures) {
3365 gclog_or_tty->print_cr("Heap:");
3366 // It helps to have the per-region information in the output to
3367 // help us track down what went wrong. This is why we call
3368 // print_extended_on() instead of print_on().
3369 print_extended_on(gclog_or_tty);
3370 gclog_or_tty->cr();
3371 gclog_or_tty->flush();
3372 }
3373 guarantee(!failures, "there should not have been any failures");
3374 } else {
3375 if (!silent) {
3376 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3377 if (G1StringDedup::is_enabled()) {
3378 gclog_or_tty->print(", StrDedup");
3379 }
3380 gclog_or_tty->print(") ");
3381 }
3382 }
3383 }
3384
3385 void G1CollectedHeap::verify(bool silent) {
3386 verify(silent, VerifyOption_G1UsePrevMarking);
3387 }
3388
3389 double G1CollectedHeap::verify(bool guard, const char* msg) {
3390 double verify_time_ms = 0.0;
3391
3392 if (guard && total_collections() >= VerifyGCStartAt) {
3393 double verify_start = os::elapsedTime();
3394 HandleMark hm; // Discard invalid handles created during verification
3395 prepare_for_verify();
3396 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3397 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3398 }
3399
3400 return verify_time_ms;
3401 }
3402
3403 void G1CollectedHeap::verify_before_gc() {
3404 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3405 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3406 }
3407
3408 void G1CollectedHeap::verify_after_gc() {
3409 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3410 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3411 }
3412
3413 class PrintRegionClosure: public HeapRegionClosure {
3414 outputStream* _st;
3415 public:
3416 PrintRegionClosure(outputStream* st) : _st(st) {}
3417 bool doHeapRegion(HeapRegion* r) {
3418 r->print_on(_st);
3419 return false;
3420 }
3421 };
3422
3423 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3424 const HeapRegion* hr,
3425 const VerifyOption vo) const {
3426 switch (vo) {
3427 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3428 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3429 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3430 default: ShouldNotReachHere();
3431 }
3432 return false; // keep some compilers happy
3433 }
3434
3435 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3436 const VerifyOption vo) const {
3437 switch (vo) {
3438 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3439 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3440 case VerifyOption_G1UseMarkWord: {
3441 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3442 return !obj->is_gc_marked() && !hr->is_archive();
3443 }
3444 default: ShouldNotReachHere();
3445 }
3446 return false; // keep some compilers happy
3447 }
3448
3449 void G1CollectedHeap::print_on(outputStream* st) const {
3450 st->print(" %-20s", "garbage-first heap");
3451 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3452 capacity()/K, used_unlocked()/K);
3453 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3454 p2i(_hrm.reserved().start()),
3455 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3456 p2i(_hrm.reserved().end()));
3457 st->cr();
3458 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3459 uint young_regions = _young_list->length();
3460 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3461 (size_t) young_regions * HeapRegion::GrainBytes / K);
3462 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3463 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3464 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3465 st->cr();
3466 MetaspaceAux::print_on(st);
3467 }
3468
3469 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3470 print_on(st);
3471
3472 // Print the per-region information.
3473 st->cr();
3474 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3475 "HS=humongous(starts), HC=humongous(continues), "
3476 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3477 "PTAMS=previous top-at-mark-start, "
3478 "NTAMS=next top-at-mark-start)");
3479 PrintRegionClosure blk(st);
3480 heap_region_iterate(&blk);
3481 }
3482
3483 void G1CollectedHeap::print_on_error(outputStream* st) const {
3484 this->CollectedHeap::print_on_error(st);
3485
3486 if (_cm != NULL) {
3487 st->cr();
3488 _cm->print_on_error(st);
3489 }
3490 }
3491
3492 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3493 workers()->print_worker_threads_on(st);
3494 _cmThread->print_on(st);
3495 st->cr();
3496 _cm->print_worker_threads_on(st);
3497 _cg1r->print_worker_threads_on(st);
3498 if (G1StringDedup::is_enabled()) {
3499 G1StringDedup::print_worker_threads_on(st);
3500 }
3501 }
3502
3503 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3504 workers()->threads_do(tc);
3505 tc->do_thread(_cmThread);
3506 _cg1r->threads_do(tc);
3507 if (G1StringDedup::is_enabled()) {
3508 G1StringDedup::threads_do(tc);
3509 }
3510 }
3511
3512 void G1CollectedHeap::print_tracing_info() const {
3513 // We'll overload this to mean "trace GC pause statistics."
3514 if (TraceYoungGenTime || TraceOldGenTime) {
3515 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3516 // to that.
3517 g1_policy()->print_tracing_info();
3518 }
3519 if (G1SummarizeRSetStats) {
3520 g1_rem_set()->print_summary_info();
3521 }
3522 if (G1SummarizeConcMark) {
3523 concurrent_mark()->print_summary_info();
3524 }
3525 g1_policy()->print_yg_surv_rate_info();
3526 }
3527
3528 #ifndef PRODUCT
3529 // Helpful for debugging RSet issues.
3530
3531 class PrintRSetsClosure : public HeapRegionClosure {
3532 private:
3533 const char* _msg;
3534 size_t _occupied_sum;
3535
3536 public:
3537 bool doHeapRegion(HeapRegion* r) {
3538 HeapRegionRemSet* hrrs = r->rem_set();
3539 size_t occupied = hrrs->occupied();
3540 _occupied_sum += occupied;
3541
3542 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3543 HR_FORMAT_PARAMS(r));
3544 if (occupied == 0) {
3545 gclog_or_tty->print_cr(" RSet is empty");
3546 } else {
3547 hrrs->print();
3548 }
3549 gclog_or_tty->print_cr("----------");
3550 return false;
3551 }
3552
3553 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3554 gclog_or_tty->cr();
3555 gclog_or_tty->print_cr("========================================");
3556 gclog_or_tty->print_cr("%s", msg);
3557 gclog_or_tty->cr();
3558 }
3559
3560 ~PrintRSetsClosure() {
3561 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3562 gclog_or_tty->print_cr("========================================");
3563 gclog_or_tty->cr();
3564 }
3565 };
3566
3567 void G1CollectedHeap::print_cset_rsets() {
3568 PrintRSetsClosure cl("Printing CSet RSets");
3569 collection_set_iterate(&cl);
3570 }
3571
3572 void G1CollectedHeap::print_all_rsets() {
3573 PrintRSetsClosure cl("Printing All RSets");;
3574 heap_region_iterate(&cl);
3575 }
3576 #endif // PRODUCT
3577
3578 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3579 YoungList* young_list = heap()->young_list();
3580
3581 size_t eden_used_bytes = young_list->eden_used_bytes();
3582 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3583
3584 size_t eden_capacity_bytes =
3585 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3586
3587 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3588 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3589 }
3590
3591 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3592 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3593 stats->unused(), stats->used(), stats->region_end_waste(),
3594 stats->regions_filled(), stats->direct_allocated(),
3595 stats->failure_used(), stats->failure_waste());
3596 }
3597
3598 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3599 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3600 gc_tracer->report_gc_heap_summary(when, heap_summary);
3601
3602 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3603 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3604 }
3605
3606
3607 G1CollectedHeap* G1CollectedHeap::heap() {
3608 CollectedHeap* heap = Universe::heap();
3609 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3610 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3611 return (G1CollectedHeap*)heap;
3612 }
3613
3614 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3615 // always_do_update_barrier = false;
3616 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3617 // Fill TLAB's and such
3618 accumulate_statistics_all_tlabs();
3619 ensure_parsability(true);
3620
3621 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3622 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3623 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3624 }
3625 }
3626
3627 void G1CollectedHeap::gc_epilogue(bool full) {
3628
3629 if (G1SummarizeRSetStats &&
3630 (G1SummarizeRSetStatsPeriod > 0) &&
3631 // we are at the end of the GC. Total collections has already been increased.
3632 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3633 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3634 }
3635
3636 // FIXME: what is this about?
3637 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3638 // is set.
3639 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3640 "derived pointer present"));
3641 // always_do_update_barrier = true;
3642
3643 resize_all_tlabs();
3644 allocation_context_stats().update(full);
3645
3646 // We have just completed a GC. Update the soft reference
3647 // policy with the new heap occupancy
3648 Universe::update_heap_info_at_gc();
3649 }
3650
3651 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3652 uint gc_count_before,
3653 bool* succeeded,
3654 GCCause::Cause gc_cause) {
3655 assert_heap_not_locked_and_not_at_safepoint();
3656 g1_policy()->record_stop_world_start();
3657 VM_G1IncCollectionPause op(gc_count_before,
3658 word_size,
3659 false, /* should_initiate_conc_mark */
3660 g1_policy()->max_pause_time_ms(),
3661 gc_cause);
3662
3663 op.set_allocation_context(AllocationContext::current());
3664 VMThread::execute(&op);
3665
3666 HeapWord* result = op.result();
3667 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3668 assert(result == NULL || ret_succeeded,
3669 "the result should be NULL if the VM did not succeed");
3670 *succeeded = ret_succeeded;
3671
3672 assert_heap_not_locked();
3673 return result;
3674 }
3675
3676 void
3677 G1CollectedHeap::doConcurrentMark() {
3678 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3679 if (!_cmThread->in_progress()) {
3680 _cmThread->set_started();
3681 CGC_lock->notify();
3682 }
3683 }
3684
3685 size_t G1CollectedHeap::pending_card_num() {
3686 size_t extra_cards = 0;
3687 JavaThread *curr = Threads::first();
3688 while (curr != NULL) {
3689 DirtyCardQueue& dcq = curr->dirty_card_queue();
3690 extra_cards += dcq.size();
3691 curr = curr->next();
3692 }
3693 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3694 size_t buffer_size = dcqs.buffer_size();
3695 size_t buffer_num = dcqs.completed_buffers_num();
3696
3697 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3698 // in bytes - not the number of 'entries'. We need to convert
3699 // into a number of cards.
3700 return (buffer_size * buffer_num + extra_cards) / oopSize;
3701 }
3702
3703 size_t G1CollectedHeap::cards_scanned() {
3704 return g1_rem_set()->cardsScanned();
3705 }
3706
3707 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3708 private:
3709 size_t _total_humongous;
3710 size_t _candidate_humongous;
3711
3712 DirtyCardQueue _dcq;
3713
3714 // We don't nominate objects with many remembered set entries, on
3715 // the assumption that such objects are likely still live.
3716 bool is_remset_small(HeapRegion* region) const {
3717 HeapRegionRemSet* const rset = region->rem_set();
3718 return G1EagerReclaimHumongousObjectsWithStaleRefs
3719 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3720 : rset->is_empty();
3721 }
3722
3723 bool is_typeArray_region(HeapRegion* region) const {
3724 return oop(region->bottom())->is_typeArray();
3725 }
3726
3727 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3728 assert(region->is_starts_humongous(), "Must start a humongous object");
3729
3730 // Candidate selection must satisfy the following constraints
3731 // while concurrent marking is in progress:
3732 //
3733 // * In order to maintain SATB invariants, an object must not be
3734 // reclaimed if it was allocated before the start of marking and
3735 // has not had its references scanned. Such an object must have
3736 // its references (including type metadata) scanned to ensure no
3737 // live objects are missed by the marking process. Objects
3738 // allocated after the start of concurrent marking don't need to
3739 // be scanned.
3740 //
3741 // * An object must not be reclaimed if it is on the concurrent
3742 // mark stack. Objects allocated after the start of concurrent
3743 // marking are never pushed on the mark stack.
3744 //
3745 // Nominating only objects allocated after the start of concurrent
3746 // marking is sufficient to meet both constraints. This may miss
3747 // some objects that satisfy the constraints, but the marking data
3748 // structures don't support efficiently performing the needed
3749 // additional tests or scrubbing of the mark stack.
3750 //
3751 // However, we presently only nominate is_typeArray() objects.
3752 // A humongous object containing references induces remembered
3753 // set entries on other regions. In order to reclaim such an
3754 // object, those remembered sets would need to be cleaned up.
3755 //
3756 // We also treat is_typeArray() objects specially, allowing them
3757 // to be reclaimed even if allocated before the start of
3758 // concurrent mark. For this we rely on mark stack insertion to
3759 // exclude is_typeArray() objects, preventing reclaiming an object
3760 // that is in the mark stack. We also rely on the metadata for
3761 // such objects to be built-in and so ensured to be kept live.
3762 // Frequent allocation and drop of large binary blobs is an
3763 // important use case for eager reclaim, and this special handling
3764 // may reduce needed headroom.
3765
3766 return is_typeArray_region(region) && is_remset_small(region);
3767 }
3768
3769 public:
3770 RegisterHumongousWithInCSetFastTestClosure()
3771 : _total_humongous(0),
3772 _candidate_humongous(0),
3773 _dcq(&JavaThread::dirty_card_queue_set()) {
3774 }
3775
3776 virtual bool doHeapRegion(HeapRegion* r) {
3777 if (!r->is_starts_humongous()) {
3778 return false;
3779 }
3780 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3781
3782 bool is_candidate = humongous_region_is_candidate(g1h, r);
3783 uint rindex = r->hrm_index();
3784 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3785 if (is_candidate) {
3786 _candidate_humongous++;
3787 g1h->register_humongous_region_with_cset(rindex);
3788 // Is_candidate already filters out humongous object with large remembered sets.
3789 // If we have a humongous object with a few remembered sets, we simply flush these
3790 // remembered set entries into the DCQS. That will result in automatic
3791 // re-evaluation of their remembered set entries during the following evacuation
3792 // phase.
3793 if (!r->rem_set()->is_empty()) {
3794 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3795 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3796 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3797 HeapRegionRemSetIterator hrrs(r->rem_set());
3798 size_t card_index;
3799 while (hrrs.has_next(card_index)) {
3800 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3801 // The remembered set might contain references to already freed
3802 // regions. Filter out such entries to avoid failing card table
3803 // verification.
3804 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3805 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3806 *card_ptr = CardTableModRefBS::dirty_card_val();
3807 _dcq.enqueue(card_ptr);
3808 }
3809 }
3810 }
3811 r->rem_set()->clear_locked();
3812 }
3813 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3814 }
3815 _total_humongous++;
3816
3817 return false;
3818 }
3819
3820 size_t total_humongous() const { return _total_humongous; }
3821 size_t candidate_humongous() const { return _candidate_humongous; }
3822
3823 void flush_rem_set_entries() { _dcq.flush(); }
3824 };
3825
3826 void G1CollectedHeap::register_humongous_regions_with_cset() {
3827 if (!G1EagerReclaimHumongousObjects) {
3828 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3829 return;
3830 }
3831 double time = os::elapsed_counter();
3832
3833 // Collect reclaim candidate information and register candidates with cset.
3834 RegisterHumongousWithInCSetFastTestClosure cl;
3835 heap_region_iterate(&cl);
3836
3837 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3838 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3839 cl.total_humongous(),
3840 cl.candidate_humongous());
3841 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3842
3843 // Finally flush all remembered set entries to re-check into the global DCQS.
3844 cl.flush_rem_set_entries();
3845 }
3846
3847 void G1CollectedHeap::setup_surviving_young_words() {
3848 assert(_surviving_young_words == NULL, "pre-condition");
3849 uint array_length = g1_policy()->young_cset_region_length();
3850 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3851 if (_surviving_young_words == NULL) {
3852 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3853 "Not enough space for young surv words summary.");
3854 }
3855 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3856 #ifdef ASSERT
3857 for (uint i = 0; i < array_length; ++i) {
3858 assert( _surviving_young_words[i] == 0, "memset above" );
3859 }
3860 #endif // !ASSERT
3861 }
3862
3863 void G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3864 assert_at_safepoint(true);
3865 uint array_length = g1_policy()->young_cset_region_length();
3866 for (uint i = 0; i < array_length; ++i) {
3867 _surviving_young_words[i] += surv_young_words[i];
3868 }
3869 }
3870
3871 void G1CollectedHeap::cleanup_surviving_young_words() {
3872 guarantee( _surviving_young_words != NULL, "pre-condition" );
3873 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3874 _surviving_young_words = NULL;
3875 }
3876
3877 #ifdef ASSERT
3878 class VerifyCSetClosure: public HeapRegionClosure {
3879 public:
3880 bool doHeapRegion(HeapRegion* hr) {
3881 // Here we check that the CSet region's RSet is ready for parallel
3882 // iteration. The fields that we'll verify are only manipulated
3883 // when the region is part of a CSet and is collected. Afterwards,
3884 // we reset these fields when we clear the region's RSet (when the
3885 // region is freed) so they are ready when the region is
3886 // re-allocated. The only exception to this is if there's an
3887 // evacuation failure and instead of freeing the region we leave
3888 // it in the heap. In that case, we reset these fields during
3889 // evacuation failure handling.
3890 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3891
3892 // Here's a good place to add any other checks we'd like to
3893 // perform on CSet regions.
3894 return false;
3895 }
3896 };
3897 #endif // ASSERT
3898
3899 uint G1CollectedHeap::num_task_queues() const {
3900 return _task_queues->size();
3901 }
3902
3903 #if TASKQUEUE_STATS
3904 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3905 st->print_raw_cr("GC Task Stats");
3906 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3907 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3908 }
3909
3910 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3911 print_taskqueue_stats_hdr(st);
3912
3913 TaskQueueStats totals;
3914 const uint n = num_task_queues();
3915 for (uint i = 0; i < n; ++i) {
3916 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3917 totals += task_queue(i)->stats;
3918 }
3919 st->print_raw("tot "); totals.print(st); st->cr();
3920
3921 DEBUG_ONLY(totals.verify());
3922 }
3923
3924 void G1CollectedHeap::reset_taskqueue_stats() {
3925 const uint n = num_task_queues();
3926 for (uint i = 0; i < n; ++i) {
3927 task_queue(i)->stats.reset();
3928 }
3929 }
3930 #endif // TASKQUEUE_STATS
3931
3932 void G1CollectedHeap::log_gc_header() {
3933 if (!G1Log::fine()) {
3934 return;
3935 }
3936
3937 gclog_or_tty->gclog_stamp();
3938
3939 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3940 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3941 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3942
3943 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3944 }
3945
3946 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3947 if (!G1Log::fine()) {
3948 return;
3949 }
3950
3951 if (G1Log::finer()) {
3952 if (evacuation_failed()) {
3953 gclog_or_tty->print(" (to-space exhausted)");
3954 }
3955 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3956 g1_policy()->phase_times()->note_gc_end();
3957 g1_policy()->phase_times()->print(pause_time_sec);
3958 g1_policy()->print_detailed_heap_transition();
3959 } else {
3960 if (evacuation_failed()) {
3961 gclog_or_tty->print("--");
3962 }
3963 g1_policy()->print_heap_transition();
3964 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3965 }
3966 gclog_or_tty->flush();
3967 }
3968
3969 void G1CollectedHeap::wait_for_root_region_scanning() {
3970 double scan_wait_start = os::elapsedTime();
3971 // We have to wait until the CM threads finish scanning the
3972 // root regions as it's the only way to ensure that all the
3973 // objects on them have been correctly scanned before we start
3974 // moving them during the GC.
3975 bool waited = _cm->root_regions()->wait_until_scan_finished();
3976 double wait_time_ms = 0.0;
3977 if (waited) {
3978 double scan_wait_end = os::elapsedTime();
3979 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3980 }
3981 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3982 }
3983
3984 bool
3985 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3986 assert_at_safepoint(true /* should_be_vm_thread */);
3987 guarantee(!is_gc_active(), "collection is not reentrant");
3988
3989 if (GC_locker::check_active_before_gc()) {
3990 return false;
3991 }
3992
3993 _gc_timer_stw->register_gc_start();
3994
3995
3996 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3997 ResourceMark rm;
3998
3999 wait_for_root_region_scanning();
4000
4001 bool should_start_conc_mark = fasle;
4002 {
4003 GCIdMark gc_id_mark;
4004 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
4005
4006 G1Log::update_level();
4007 print_heap_before_gc();
4008 trace_heap_before_gc(_gc_tracer_stw);
4009
4010 verify_region_sets_optional();
4011 verify_dirty_young_regions();
4012
4013 // This call will decide whether this pause is an initial-mark
4014 // pause. If it is, during_initial_mark_pause() will return true
4015 // for the duration of this pause.
4016 g1_policy()->decide_on_conc_mark_initiation();
4017
4018 // We do not allow initial-mark to be piggy-backed on a mixed GC.
4019 assert(!collector_state()->during_initial_mark_pause() ||
4020 collector_state()->gcs_are_young(), "sanity");
4021
4022 // We also do not allow mixed GCs during marking.
4023 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4024
4025 // Record whether this pause is an initial mark. When the current
4026 // thread has completed its logging output and it's safe to signal
4027 // the CM thread, the flag's value in the policy has been reset.
4028 should_start_conc_mark = collector_state()->during_initial_mark_pause();
4029
4030 // Inner scope for scope based logging, timers, and stats collection
4031 {
4032 EvacuationInfo evacuation_info;
4033
4034 if (collector_state()->during_initial_mark_pause()) {
4035 // We are about to start a marking cycle, so we increment the
4036 // full collection counter.
4037 increment_old_marking_cycles_started();
4038 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4039 }
4040
4041 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4042
4043 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4044
4045 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4046 workers()->active_workers(),
4047 Threads::number_of_non_daemon_threads());
4048 workers()->set_active_workers(active_workers);
4049
4050 double pause_start_sec = os::elapsedTime();
4051 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4052 log_gc_header();
4053
4054 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4055 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4056
4057 // If the secondary_free_list is not empty, append it to the
4058 // free_list. No need to wait for the cleanup operation to finish;
4059 // the region allocation code will check the secondary_free_list
4060 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4061 // set, skip this step so that the region allocation code has to
4062 // get entries from the secondary_free_list.
4063 if (!G1StressConcRegionFreeing) {
4064 append_secondary_free_list_if_not_empty_with_lock();
4065 }
4066
4067 assert(check_young_list_well_formed(), "young list should be well formed");
4068
4069 // Don't dynamically change the number of GC threads this early. A value of
4070 // 0 is used to indicate serial work. When parallel work is done,
4071 // it will be set.
4072
4073 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4074 IsGCActiveMark x;
4075
4076 gc_prologue(false);
4077 increment_total_collections(false /* full gc */);
4078 increment_gc_time_stamp();
4079
4080 verify_before_gc();
4081
4082 check_bitmaps("GC Start");
4083
4084 COMPILER2_PRESENT(DerivedPointerTable::clear());
4085
4086 // Please see comment in g1CollectedHeap.hpp and
4087 // G1CollectedHeap::ref_processing_init() to see how
4088 // reference processing currently works in G1.
4089
4090 // Enable discovery in the STW reference processor
4091 ref_processor_stw()->enable_discovery();
4092
4093 {
4094 // We want to temporarily turn off discovery by the
4095 // CM ref processor, if necessary, and turn it back on
4096 // on again later if we do. Using a scoped
4097 // NoRefDiscovery object will do this.
4098 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4099
4100 // Forget the current alloc region (we might even choose it to be part
4101 // of the collection set!).
4102 _allocator->release_mutator_alloc_region();
4103
4104 // We should call this after we retire the mutator alloc
4105 // region(s) so that all the ALLOC / RETIRE events are generated
4106 // before the start GC event.
4107 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4108
4109 // This timing is only used by the ergonomics to handle our pause target.
4110 // It is unclear why this should not include the full pause. We will
4111 // investigate this in CR 7178365.
4112 //
4113 // Preserving the old comment here if that helps the investigation:
4114 //
4115 // The elapsed time induced by the start time below deliberately elides
4116 // the possible verification above.
4117 double sample_start_time_sec = os::elapsedTime();
4118
4119 #if YOUNG_LIST_VERBOSE
4120 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4121 _young_list->print();
4122 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4123 #endif // YOUNG_LIST_VERBOSE
4124
4125 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4126
4127 #if YOUNG_LIST_VERBOSE
4128 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4129 _young_list->print();
4130 #endif // YOUNG_LIST_VERBOSE
4131
4132 if (collector_state()->during_initial_mark_pause()) {
4133 concurrent_mark()->checkpointRootsInitialPre();
4134 }
4135
4136 #if YOUNG_LIST_VERBOSE
4137 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4138 _young_list->print();
4139 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4140 #endif // YOUNG_LIST_VERBOSE
4141
4142 g1_policy()->finalize_cset(target_pause_time_ms);
4143
4144 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4145
4146 register_humongous_regions_with_cset();
4147
4148 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4149
4150 _cm->note_start_of_gc();
4151 // We call this after finalize_cset() to
4152 // ensure that the CSet has been finalized.
4153 _cm->verify_no_cset_oops();
4154
4155 if (_hr_printer.is_active()) {
4156 HeapRegion* hr = g1_policy()->collection_set();
4157 while (hr != NULL) {
4158 _hr_printer.cset(hr);
4159 hr = hr->next_in_collection_set();
4160 }
4161 }
4162
4163 #ifdef ASSERT
4164 VerifyCSetClosure cl;
4165 collection_set_iterate(&cl);
4166 #endif // ASSERT
4167
4168 setup_surviving_young_words();
4169
4170 // Initialize the GC alloc regions.
4171 _allocator->init_gc_alloc_regions(evacuation_info);
4172
4173 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers());
4174 // Actually do the work...
4175 evacuate_collection_set(evacuation_info, &per_thread_states);
4176
4177 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4178
4179 eagerly_reclaim_humongous_regions();
4180
4181 g1_policy()->clear_collection_set();
4182
4183 cleanup_surviving_young_words();
4184
4185 // Start a new incremental collection set for the next pause.
4186 g1_policy()->start_incremental_cset_building();
4187
4188 clear_cset_fast_test();
4189
4190 _young_list->reset_sampled_info();
4191
4192 // Don't check the whole heap at this point as the
4193 // GC alloc regions from this pause have been tagged
4194 // as survivors and moved on to the survivor list.
4195 // Survivor regions will fail the !is_young() check.
4196 assert(check_young_list_empty(false /* check_heap */),
4197 "young list should be empty");
4198
4199 #if YOUNG_LIST_VERBOSE
4200 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4201 _young_list->print();
4202 #endif // YOUNG_LIST_VERBOSE
4203
4204 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4205 _young_list->first_survivor_region(),
4206 _young_list->last_survivor_region());
4207
4208 _young_list->reset_auxilary_lists();
4209
4210 if (evacuation_failed()) {
4211 set_used(recalculate_used());
4212 if (_archive_allocator != NULL) {
4213 _archive_allocator->clear_used();
4214 }
4215 for (uint i = 0; i < ParallelGCThreads; i++) {
4216 if (_evacuation_failed_info_array[i].has_failed()) {
4217 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4218 }
4219 }
4220 } else {
4221 // The "used" of the the collection set have already been subtracted
4222 // when they were freed. Add in the bytes evacuated.
4223 increase_used(g1_policy()->bytes_copied_during_gc());
4224 }
4225
4226 if (collector_state()->during_initial_mark_pause()) {
4227 // We have to do this before we notify the CM threads that
4228 // they can start working to make sure that all the
4229 // appropriate initialization is done on the CM object.
4230 concurrent_mark()->checkpointRootsInitialPost();
4231 collector_state()->set_mark_in_progress(true);
4232 // Note that we don't actually trigger the CM thread at
4233 // this point. We do that later when we're sure that
4234 // the current thread has completed its logging output.
4235 }
4236
4237 allocate_dummy_regions();
4238
4239 #if YOUNG_LIST_VERBOSE
4240 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4241 _young_list->print();
4242 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4243 #endif // YOUNG_LIST_VERBOSE
4244
4245 _allocator->init_mutator_alloc_region();
4246
4247 {
4248 size_t expand_bytes = g1_policy()->expansion_amount();
4249 if (expand_bytes > 0) {
4250 size_t bytes_before = capacity();
4251 // No need for an ergo verbose message here,
4252 // expansion_amount() does this when it returns a value > 0.
4253 if (!expand(expand_bytes)) {
4254 // We failed to expand the heap. Cannot do anything about it.
4255 }
4256 }
4257 }
4258
4259 // We redo the verification but now wrt to the new CSet which
4260 // has just got initialized after the previous CSet was freed.
4261 _cm->verify_no_cset_oops();
4262 _cm->note_end_of_gc();
4263
4264 // This timing is only used by the ergonomics to handle our pause target.
4265 // It is unclear why this should not include the full pause. We will
4266 // investigate this in CR 7178365.
4267 double sample_end_time_sec = os::elapsedTime();
4268 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4269 g1_policy()->record_collection_pause_end(pause_time_ms);
4270
4271 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4272 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4273
4274 MemoryService::track_memory_usage();
4275
4276 // In prepare_for_verify() below we'll need to scan the deferred
4277 // update buffers to bring the RSets up-to-date if
4278 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4279 // the update buffers we'll probably need to scan cards on the
4280 // regions we just allocated to (i.e., the GC alloc
4281 // regions). However, during the last GC we called
4282 // set_saved_mark() on all the GC alloc regions, so card
4283 // scanning might skip the [saved_mark_word()...top()] area of
4284 // those regions (i.e., the area we allocated objects into
4285 // during the last GC). But it shouldn't. Given that
4286 // saved_mark_word() is conditional on whether the GC time stamp
4287 // on the region is current or not, by incrementing the GC time
4288 // stamp here we invalidate all the GC time stamps on all the
4289 // regions and saved_mark_word() will simply return top() for
4290 // all the regions. This is a nicer way of ensuring this rather
4291 // than iterating over the regions and fixing them. In fact, the
4292 // GC time stamp increment here also ensures that
4293 // saved_mark_word() will return top() between pauses, i.e.,
4294 // during concurrent refinement. So we don't need the
4295 // is_gc_active() check to decided which top to use when
4296 // scanning cards (see CR 7039627).
4297 increment_gc_time_stamp();
4298
4299 verify_after_gc();
4300 check_bitmaps("GC End");
4301
4302 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4303 ref_processor_stw()->verify_no_references_recorded();
4304
4305 // CM reference discovery will be re-enabled if necessary.
4306 }
4307
4308 // We should do this after we potentially expand the heap so
4309 // that all the COMMIT events are generated before the end GC
4310 // event, and after we retire the GC alloc regions so that all
4311 // RETIRE events are generated before the end GC event.
4312 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4313
4314 #ifdef TRACESPINNING
4315 ParallelTaskTerminator::print_termination_counts();
4316 #endif
4317
4318 gc_epilogue(false);
4319 }
4320
4321 // Print the remainder of the GC log output.
4322 log_gc_footer(os::elapsedTime() - pause_start_sec);
4323
4324 // It is not yet to safe to tell the concurrent mark to
4325 // start as we have some optional output below. We don't want the
4326 // output from the concurrent mark thread interfering with this
4327 // logging output either.
4328
4329 _hrm.verify_optional();
4330 verify_region_sets_optional();
4331
4332 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4333 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4334
4335 print_heap_after_gc();
4336 trace_heap_after_gc(_gc_tracer_stw);
4337
4338 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4339 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4340 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4341 // before any GC notifications are raised.
4342 g1mm()->update_sizes();
4343
4344 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4345 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4346 _gc_timer_stw->register_gc_end();
4347 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4348 }
4349 // It should now be safe to tell the concurrent mark thread to start
4350 // without its logging output interfering with the logging output
4351 // that came from the pause.
4352 }
4353
4354 if (should_start_conc_mark) {
4355 // CAUTION: after the doConcurrentMark() call below,
4356 // the concurrent marking thread(s) could be running
4357 // concurrently with us. Make sure that anything after
4358 // this point does not assume that we are the only GC thread
4359 // running. Note: of course, the actual marking work will
4360 // not start until the safepoint itself is released in
4361 // SuspendibleThreadSet::desynchronize().
4362 doConcurrentMark();
4363 }
4364
4365 return true;
4366 }
4367
4368 void G1CollectedHeap::remove_self_forwarding_pointers() {
4369 double remove_self_forwards_start = os::elapsedTime();
4370
4371 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4372 workers()->run_task(&rsfp_task);
4373
4374 // Now restore saved marks, if any.
4375 for (uint i = 0; i < ParallelGCThreads; i++) {
4376 OopAndMarkOopStack& cur = _preserved_objs[i];
4377 while (!cur.is_empty()) {
4378 OopAndMarkOop elem = cur.pop();
4379 elem.set_mark();
4380 }
4381 cur.clear(true);
4382 }
4383
4384 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4385 }
4386
4387 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4388 if (!_evacuation_failed) {
4389 _evacuation_failed = true;
4390 }
4391
4392 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4393
4394 // We want to call the "for_promotion_failure" version only in the
4395 // case of a promotion failure.
4396 if (m->must_be_preserved_for_promotion_failure(obj)) {
4397 OopAndMarkOop elem(obj, m);
4398 _preserved_objs[worker_id].push(elem);
4399 }
4400 }
4401
4402 void G1ParCopyHelper::mark_object(oop obj) {
4403 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4404
4405 // We know that the object is not moving so it's safe to read its size.
4406 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4407 }
4408
4409 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4410 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4411 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4412 assert(from_obj != to_obj, "should not be self-forwarded");
4413
4414 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4415 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4416
4417 // The object might be in the process of being copied by another
4418 // worker so we cannot trust that its to-space image is
4419 // well-formed. So we have to read its size from its from-space
4420 // image which we know should not be changing.
4421 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4422 }
4423
4424 template <class T>
4425 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4426 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4427 _scanned_klass->record_modified_oops();
4428 }
4429 }
4430
4431 template <G1Barrier barrier, G1Mark do_mark_object>
4432 template <class T>
4433 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4434 T heap_oop = oopDesc::load_heap_oop(p);
4435
4436 if (oopDesc::is_null(heap_oop)) {
4437 return;
4438 }
4439
4440 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4441
4442 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4443
4444 const InCSetState state = _g1->in_cset_state(obj);
4445 if (state.is_in_cset()) {
4446 oop forwardee;
4447 markOop m = obj->mark();
4448 if (m->is_marked()) {
4449 forwardee = (oop) m->decode_pointer();
4450 } else {
4451 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4452 }
4453 assert(forwardee != NULL, "forwardee should not be NULL");
4454 oopDesc::encode_store_heap_oop(p, forwardee);
4455 if (do_mark_object != G1MarkNone && forwardee != obj) {
4456 // If the object is self-forwarded we don't need to explicitly
4457 // mark it, the evacuation failure protocol will do so.
4458 mark_forwarded_object(obj, forwardee);
4459 }
4460
4461 if (barrier == G1BarrierKlass) {
4462 do_klass_barrier(p, forwardee);
4463 }
4464 } else {
4465 if (state.is_humongous()) {
4466 _g1->set_humongous_is_live(obj);
4467 }
4468 // The object is not in collection set. If we're a root scanning
4469 // closure during an initial mark pause then attempt to mark the object.
4470 if (do_mark_object == G1MarkFromRoot) {
4471 mark_object(obj);
4472 }
4473 }
4474 }
4475
4476 class G1ParEvacuateFollowersClosure : public VoidClosure {
4477 private:
4478 double _start_term;
4479 double _term_time;
4480 size_t _term_attempts;
4481
4482 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4483 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4484 protected:
4485 G1CollectedHeap* _g1h;
4486 G1ParScanThreadState* _par_scan_state;
4487 RefToScanQueueSet* _queues;
4488 ParallelTaskTerminator* _terminator;
4489
4490 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4491 RefToScanQueueSet* queues() { return _queues; }
4492 ParallelTaskTerminator* terminator() { return _terminator; }
4493
4494 public:
4495 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4496 G1ParScanThreadState* par_scan_state,
4497 RefToScanQueueSet* queues,
4498 ParallelTaskTerminator* terminator)
4499 : _g1h(g1h), _par_scan_state(par_scan_state),
4500 _queues(queues), _terminator(terminator),
4501 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4502
4503 void do_void();
4504
4505 double term_time() const { return _term_time; }
4506 size_t term_attempts() const { return _term_attempts; }
4507
4508 private:
4509 inline bool offer_termination();
4510 };
4511
4512 bool G1ParEvacuateFollowersClosure::offer_termination() {
4513 G1ParScanThreadState* const pss = par_scan_state();
4514 start_term_time();
4515 const bool res = terminator()->offer_termination();
4516 end_term_time();
4517 return res;
4518 }
4519
4520 void G1ParEvacuateFollowersClosure::do_void() {
4521 G1ParScanThreadState* const pss = par_scan_state();
4522 pss->trim_queue();
4523 do {
4524 pss->steal_and_trim_queue(queues());
4525 } while (!offer_termination());
4526 }
4527
4528 class G1KlassScanClosure : public KlassClosure {
4529 G1ParCopyHelper* _closure;
4530 bool _process_only_dirty;
4531 int _count;
4532 public:
4533 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4534 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4535 void do_klass(Klass* klass) {
4536 // If the klass has not been dirtied we know that there's
4537 // no references into the young gen and we can skip it.
4538 if (!_process_only_dirty || klass->has_modified_oops()) {
4539 // Clean the klass since we're going to scavenge all the metadata.
4540 klass->clear_modified_oops();
4541
4542 // Tell the closure that this klass is the Klass to scavenge
4543 // and is the one to dirty if oops are left pointing into the young gen.
4544 _closure->set_scanned_klass(klass);
4545
4546 klass->oops_do(_closure);
4547
4548 _closure->set_scanned_klass(NULL);
4549 }
4550 _count++;
4551 }
4552 };
4553
4554 class G1ParTask : public AbstractGangTask {
4555 protected:
4556 G1CollectedHeap* _g1h;
4557 G1ParScanThreadStateSet* _pss;
4558 RefToScanQueueSet* _queues;
4559 G1RootProcessor* _root_processor;
4560 ParallelTaskTerminator _terminator;
4561 uint _n_workers;
4562
4563 public:
4564 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4565 : AbstractGangTask("G1 collection"),
4566 _g1h(g1h),
4567 _pss(per_thread_states),
4568 _queues(task_queues),
4569 _root_processor(root_processor),
4570 _terminator(n_workers, _queues),
4571 _n_workers(n_workers)
4572 {}
4573
4574 RefToScanQueueSet* queues() { return _queues; }
4575
4576 RefToScanQueue *work_queue(int i) {
4577 return queues()->queue(i);
4578 }
4579
4580 ParallelTaskTerminator* terminator() { return &_terminator; }
4581
4582 // Helps out with CLD processing.
4583 //
4584 // During InitialMark we need to:
4585 // 1) Scavenge all CLDs for the young GC.
4586 // 2) Mark all objects directly reachable from strong CLDs.
4587 template <G1Mark do_mark_object>
4588 class G1CLDClosure : public CLDClosure {
4589 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4590 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4591 G1KlassScanClosure _klass_in_cld_closure;
4592 bool _claim;
4593
4594 public:
4595 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4596 bool only_young, bool claim)
4597 : _oop_closure(oop_closure),
4598 _oop_in_klass_closure(oop_closure->g1(),
4599 oop_closure->pss()),
4600 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4601 _claim(claim) {
4602
4603 }
4604
4605 void do_cld(ClassLoaderData* cld) {
4606 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4607 }
4608 };
4609
4610 void work(uint worker_id) {
4611 if (worker_id >= _n_workers) return; // no work needed this round
4612
4613 double start_sec = os::elapsedTime();
4614 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4615
4616 {
4617 ResourceMark rm;
4618 HandleMark hm;
4619
4620 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4621
4622 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4623 pss->set_ref_processor(rp);
4624
4625 bool only_young = _g1h->collector_state()->gcs_are_young();
4626
4627 // Non-IM young GC.
4628 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss);
4629 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4630 only_young, // Only process dirty klasses.
4631 false); // No need to claim CLDs.
4632 // IM young GC.
4633 // Strong roots closures.
4634 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss);
4635 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4636 false, // Process all klasses.
4637 true); // Need to claim CLDs.
4638 // Weak roots closures.
4639 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4640 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4641 false, // Process all klasses.
4642 true); // Need to claim CLDs.
4643
4644 OopClosure* strong_root_cl;
4645 OopClosure* weak_root_cl;
4646 CLDClosure* strong_cld_cl;
4647 CLDClosure* weak_cld_cl;
4648
4649 bool trace_metadata = false;
4650
4651 if (_g1h->collector_state()->during_initial_mark_pause()) {
4652 // We also need to mark copied objects.
4653 strong_root_cl = &scan_mark_root_cl;
4654 strong_cld_cl = &scan_mark_cld_cl;
4655 if (ClassUnloadingWithConcurrentMark) {
4656 weak_root_cl = &scan_mark_weak_root_cl;
4657 weak_cld_cl = &scan_mark_weak_cld_cl;
4658 trace_metadata = true;
4659 } else {
4660 weak_root_cl = &scan_mark_root_cl;
4661 weak_cld_cl = &scan_mark_cld_cl;
4662 }
4663 } else {
4664 strong_root_cl = &scan_only_root_cl;
4665 weak_root_cl = &scan_only_root_cl;
4666 strong_cld_cl = &scan_only_cld_cl;
4667 weak_cld_cl = &scan_only_cld_cl;
4668 }
4669
4670 double start_strong_roots_sec = os::elapsedTime();
4671 _root_processor->evacuate_roots(strong_root_cl,
4672 weak_root_cl,
4673 strong_cld_cl,
4674 weak_cld_cl,
4675 trace_metadata,
4676 worker_id);
4677
4678 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4679 _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4680 weak_root_cl,
4681 worker_id);
4682 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4683
4684 double term_sec = 0.0;
4685 size_t evac_term_attempts = 0;
4686 {
4687 double start = os::elapsedTime();
4688 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4689 evac.do_void();
4690
4691 evac_term_attempts = evac.term_attempts();
4692 term_sec = evac.term_time();
4693 double elapsed_sec = os::elapsedTime() - start;
4694 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4695 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4696 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4697 }
4698
4699 assert(pss->queue_is_empty(), "should be empty");
4700
4701 if (PrintTerminationStats) {
4702 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4703 size_t lab_waste;
4704 size_t lab_undo_waste;
4705 pss->waste(lab_waste, lab_undo_waste);
4706 _g1h->print_termination_stats(gclog_or_tty,
4707 worker_id,
4708 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4709 strong_roots_sec * 1000.0, /* strong roots time */
4710 term_sec * 1000.0, /* evac term time */
4711 evac_term_attempts, /* evac term attempts */
4712 lab_waste, /* alloc buffer waste */
4713 lab_undo_waste /* undo waste */
4714 );
4715 }
4716
4717 // Close the inner scope so that the ResourceMark and HandleMark
4718 // destructors are executed here and are included as part of the
4719 // "GC Worker Time".
4720 }
4721 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4722 }
4723 };
4724
4725 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4726 st->print_raw_cr("GC Termination Stats");
4727 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4728 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4729 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4730 }
4731
4732 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4733 uint worker_id,
4734 double elapsed_ms,
4735 double strong_roots_ms,
4736 double term_ms,
4737 size_t term_attempts,
4738 size_t alloc_buffer_waste,
4739 size_t undo_waste) const {
4740 st->print_cr("%3d %9.2f %9.2f %6.2f "
4741 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4742 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4743 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4744 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4745 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4746 alloc_buffer_waste * HeapWordSize / K,
4747 undo_waste * HeapWordSize / K);
4748 }
4749
4750 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4751 private:
4752 BoolObjectClosure* _is_alive;
4753 int _initial_string_table_size;
4754 int _initial_symbol_table_size;
4755
4756 bool _process_strings;
4757 int _strings_processed;
4758 int _strings_removed;
4759
4760 bool _process_symbols;
4761 int _symbols_processed;
4762 int _symbols_removed;
4763
4764 public:
4765 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4766 AbstractGangTask("String/Symbol Unlinking"),
4767 _is_alive(is_alive),
4768 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4769 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4770
4771 _initial_string_table_size = StringTable::the_table()->table_size();
4772 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4773 if (process_strings) {
4774 StringTable::clear_parallel_claimed_index();
4775 }
4776 if (process_symbols) {
4777 SymbolTable::clear_parallel_claimed_index();
4778 }
4779 }
4780
4781 ~G1StringSymbolTableUnlinkTask() {
4782 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4783 err_msg("claim value %d after unlink less than initial string table size %d",
4784 StringTable::parallel_claimed_index(), _initial_string_table_size));
4785 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4786 err_msg("claim value %d after unlink less than initial symbol table size %d",
4787 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4788
4789 if (G1TraceStringSymbolTableScrubbing) {
4790 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4791 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4792 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4793 strings_processed(), strings_removed(),
4794 symbols_processed(), symbols_removed());
4795 }
4796 }
4797
4798 void work(uint worker_id) {
4799 int strings_processed = 0;
4800 int strings_removed = 0;
4801 int symbols_processed = 0;
4802 int symbols_removed = 0;
4803 if (_process_strings) {
4804 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4805 Atomic::add(strings_processed, &_strings_processed);
4806 Atomic::add(strings_removed, &_strings_removed);
4807 }
4808 if (_process_symbols) {
4809 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4810 Atomic::add(symbols_processed, &_symbols_processed);
4811 Atomic::add(symbols_removed, &_symbols_removed);
4812 }
4813 }
4814
4815 size_t strings_processed() const { return (size_t)_strings_processed; }
4816 size_t strings_removed() const { return (size_t)_strings_removed; }
4817
4818 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4819 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4820 };
4821
4822 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4823 private:
4824 static Monitor* _lock;
4825
4826 BoolObjectClosure* const _is_alive;
4827 const bool _unloading_occurred;
4828 const uint _num_workers;
4829
4830 // Variables used to claim nmethods.
4831 nmethod* _first_nmethod;
4832 volatile nmethod* _claimed_nmethod;
4833
4834 // The list of nmethods that need to be processed by the second pass.
4835 volatile nmethod* _postponed_list;
4836 volatile uint _num_entered_barrier;
4837
4838 public:
4839 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4840 _is_alive(is_alive),
4841 _unloading_occurred(unloading_occurred),
4842 _num_workers(num_workers),
4843 _first_nmethod(NULL),
4844 _claimed_nmethod(NULL),
4845 _postponed_list(NULL),
4846 _num_entered_barrier(0)
4847 {
4848 nmethod::increase_unloading_clock();
4849 // Get first alive nmethod
4850 NMethodIterator iter = NMethodIterator();
4851 if(iter.next_alive()) {
4852 _first_nmethod = iter.method();
4853 }
4854 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4855 }
4856
4857 ~G1CodeCacheUnloadingTask() {
4858 CodeCache::verify_clean_inline_caches();
4859
4860 CodeCache::set_needs_cache_clean(false);
4861 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4862
4863 CodeCache::verify_icholder_relocations();
4864 }
4865
4866 private:
4867 void add_to_postponed_list(nmethod* nm) {
4868 nmethod* old;
4869 do {
4870 old = (nmethod*)_postponed_list;
4871 nm->set_unloading_next(old);
4872 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4873 }
4874
4875 void clean_nmethod(nmethod* nm) {
4876 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4877
4878 if (postponed) {
4879 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4880 add_to_postponed_list(nm);
4881 }
4882
4883 // Mark that this thread has been cleaned/unloaded.
4884 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4885 nm->set_unloading_clock(nmethod::global_unloading_clock());
4886 }
4887
4888 void clean_nmethod_postponed(nmethod* nm) {
4889 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4890 }
4891
4892 static const int MaxClaimNmethods = 16;
4893
4894 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4895 nmethod* first;
4896 NMethodIterator last;
4897
4898 do {
4899 *num_claimed_nmethods = 0;
4900
4901 first = (nmethod*)_claimed_nmethod;
4902 last = NMethodIterator(first);
4903
4904 if (first != NULL) {
4905
4906 for (int i = 0; i < MaxClaimNmethods; i++) {
4907 if (!last.next_alive()) {
4908 break;
4909 }
4910 claimed_nmethods[i] = last.method();
4911 (*num_claimed_nmethods)++;
4912 }
4913 }
4914
4915 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4916 }
4917
4918 nmethod* claim_postponed_nmethod() {
4919 nmethod* claim;
4920 nmethod* next;
4921
4922 do {
4923 claim = (nmethod*)_postponed_list;
4924 if (claim == NULL) {
4925 return NULL;
4926 }
4927
4928 next = claim->unloading_next();
4929
4930 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4931
4932 return claim;
4933 }
4934
4935 public:
4936 // Mark that we're done with the first pass of nmethod cleaning.
4937 void barrier_mark(uint worker_id) {
4938 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4939 _num_entered_barrier++;
4940 if (_num_entered_barrier == _num_workers) {
4941 ml.notify_all();
4942 }
4943 }
4944
4945 // See if we have to wait for the other workers to
4946 // finish their first-pass nmethod cleaning work.
4947 void barrier_wait(uint worker_id) {
4948 if (_num_entered_barrier < _num_workers) {
4949 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4950 while (_num_entered_barrier < _num_workers) {
4951 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4952 }
4953 }
4954 }
4955
4956 // Cleaning and unloading of nmethods. Some work has to be postponed
4957 // to the second pass, when we know which nmethods survive.
4958 void work_first_pass(uint worker_id) {
4959 // The first nmethods is claimed by the first worker.
4960 if (worker_id == 0 && _first_nmethod != NULL) {
4961 clean_nmethod(_first_nmethod);
4962 _first_nmethod = NULL;
4963 }
4964
4965 int num_claimed_nmethods;
4966 nmethod* claimed_nmethods[MaxClaimNmethods];
4967
4968 while (true) {
4969 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4970
4971 if (num_claimed_nmethods == 0) {
4972 break;
4973 }
4974
4975 for (int i = 0; i < num_claimed_nmethods; i++) {
4976 clean_nmethod(claimed_nmethods[i]);
4977 }
4978 }
4979 }
4980
4981 void work_second_pass(uint worker_id) {
4982 nmethod* nm;
4983 // Take care of postponed nmethods.
4984 while ((nm = claim_postponed_nmethod()) != NULL) {
4985 clean_nmethod_postponed(nm);
4986 }
4987 }
4988 };
4989
4990 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4991
4992 class G1KlassCleaningTask : public StackObj {
4993 BoolObjectClosure* _is_alive;
4994 volatile jint _clean_klass_tree_claimed;
4995 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4996
4997 public:
4998 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4999 _is_alive(is_alive),
5000 _clean_klass_tree_claimed(0),
5001 _klass_iterator() {
5002 }
5003
5004 private:
5005 bool claim_clean_klass_tree_task() {
5006 if (_clean_klass_tree_claimed) {
5007 return false;
5008 }
5009
5010 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5011 }
5012
5013 InstanceKlass* claim_next_klass() {
5014 Klass* klass;
5015 do {
5016 klass =_klass_iterator.next_klass();
5017 } while (klass != NULL && !klass->oop_is_instance());
5018
5019 return (InstanceKlass*)klass;
5020 }
5021
5022 public:
5023
5024 void clean_klass(InstanceKlass* ik) {
5025 ik->clean_implementors_list(_is_alive);
5026 ik->clean_method_data(_is_alive);
5027
5028 // G1 specific cleanup work that has
5029 // been moved here to be done in parallel.
5030 ik->clean_dependent_nmethods();
5031 }
5032
5033 void work() {
5034 ResourceMark rm;
5035
5036 // One worker will clean the subklass/sibling klass tree.
5037 if (claim_clean_klass_tree_task()) {
5038 Klass::clean_subklass_tree(_is_alive);
5039 }
5040
5041 // All workers will help cleaning the classes,
5042 InstanceKlass* klass;
5043 while ((klass = claim_next_klass()) != NULL) {
5044 clean_klass(klass);
5045 }
5046 }
5047 };
5048
5049 // To minimize the remark pause times, the tasks below are done in parallel.
5050 class G1ParallelCleaningTask : public AbstractGangTask {
5051 private:
5052 G1StringSymbolTableUnlinkTask _string_symbol_task;
5053 G1CodeCacheUnloadingTask _code_cache_task;
5054 G1KlassCleaningTask _klass_cleaning_task;
5055
5056 public:
5057 // The constructor is run in the VMThread.
5058 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5059 AbstractGangTask("Parallel Cleaning"),
5060 _string_symbol_task(is_alive, process_strings, process_symbols),
5061 _code_cache_task(num_workers, is_alive, unloading_occurred),
5062 _klass_cleaning_task(is_alive) {
5063 }
5064
5065 // The parallel work done by all worker threads.
5066 void work(uint worker_id) {
5067 // Do first pass of code cache cleaning.
5068 _code_cache_task.work_first_pass(worker_id);
5069
5070 // Let the threads mark that the first pass is done.
5071 _code_cache_task.barrier_mark(worker_id);
5072
5073 // Clean the Strings and Symbols.
5074 _string_symbol_task.work(worker_id);
5075
5076 // Wait for all workers to finish the first code cache cleaning pass.
5077 _code_cache_task.barrier_wait(worker_id);
5078
5079 // Do the second code cache cleaning work, which realize on
5080 // the liveness information gathered during the first pass.
5081 _code_cache_task.work_second_pass(worker_id);
5082
5083 // Clean all klasses that were not unloaded.
5084 _klass_cleaning_task.work();
5085 }
5086 };
5087
5088
5089 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5090 bool process_strings,
5091 bool process_symbols,
5092 bool class_unloading_occurred) {
5093 uint n_workers = workers()->active_workers();
5094
5095 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5096 n_workers, class_unloading_occurred);
5097 workers()->run_task(&g1_unlink_task);
5098 }
5099
5100 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5101 bool process_strings, bool process_symbols) {
5102 {
5103 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5104 workers()->run_task(&g1_unlink_task);
5105 }
5106
5107 if (G1StringDedup::is_enabled()) {
5108 G1StringDedup::unlink(is_alive);
5109 }
5110 }
5111
5112 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5113 private:
5114 DirtyCardQueueSet* _queue;
5115 public:
5116 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5117
5118 virtual void work(uint worker_id) {
5119 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5120 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5121
5122 RedirtyLoggedCardTableEntryClosure cl;
5123 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5124
5125 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5126 }
5127 };
5128
5129 void G1CollectedHeap::redirty_logged_cards() {
5130 double redirty_logged_cards_start = os::elapsedTime();
5131
5132 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5133 dirty_card_queue_set().reset_for_par_iteration();
5134 workers()->run_task(&redirty_task);
5135
5136 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5137 dcq.merge_bufferlists(&dirty_card_queue_set());
5138 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5139
5140 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5141 }
5142
5143 // Weak Reference Processing support
5144
5145 // An always "is_alive" closure that is used to preserve referents.
5146 // If the object is non-null then it's alive. Used in the preservation
5147 // of referent objects that are pointed to by reference objects
5148 // discovered by the CM ref processor.
5149 class G1AlwaysAliveClosure: public BoolObjectClosure {
5150 G1CollectedHeap* _g1;
5151 public:
5152 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5153 bool do_object_b(oop p) {
5154 if (p != NULL) {
5155 return true;
5156 }
5157 return false;
5158 }
5159 };
5160
5161 bool G1STWIsAliveClosure::do_object_b(oop p) {
5162 // An object is reachable if it is outside the collection set,
5163 // or is inside and copied.
5164 return !_g1->is_in_cset(p) || p->is_forwarded();
5165 }
5166
5167 // Non Copying Keep Alive closure
5168 class G1KeepAliveClosure: public OopClosure {
5169 G1CollectedHeap* _g1;
5170 public:
5171 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5172 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5173 void do_oop(oop* p) {
5174 oop obj = *p;
5175 assert(obj != NULL, "the caller should have filtered out NULL values");
5176
5177 const InCSetState cset_state = _g1->in_cset_state(obj);
5178 if (!cset_state.is_in_cset_or_humongous()) {
5179 return;
5180 }
5181 if (cset_state.is_in_cset()) {
5182 assert( obj->is_forwarded(), "invariant" );
5183 *p = obj->forwardee();
5184 } else {
5185 assert(!obj->is_forwarded(), "invariant" );
5186 assert(cset_state.is_humongous(),
5187 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5188 _g1->set_humongous_is_live(obj);
5189 }
5190 }
5191 };
5192
5193 // Copying Keep Alive closure - can be called from both
5194 // serial and parallel code as long as different worker
5195 // threads utilize different G1ParScanThreadState instances
5196 // and different queues.
5197
5198 class G1CopyingKeepAliveClosure: public OopClosure {
5199 G1CollectedHeap* _g1h;
5200 OopClosure* _copy_non_heap_obj_cl;
5201 G1ParScanThreadState* _par_scan_state;
5202
5203 public:
5204 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5205 OopClosure* non_heap_obj_cl,
5206 G1ParScanThreadState* pss):
5207 _g1h(g1h),
5208 _copy_non_heap_obj_cl(non_heap_obj_cl),
5209 _par_scan_state(pss)
5210 {}
5211
5212 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5213 virtual void do_oop( oop* p) { do_oop_work(p); }
5214
5215 template <class T> void do_oop_work(T* p) {
5216 oop obj = oopDesc::load_decode_heap_oop(p);
5217
5218 if (_g1h->is_in_cset_or_humongous(obj)) {
5219 // If the referent object has been forwarded (either copied
5220 // to a new location or to itself in the event of an
5221 // evacuation failure) then we need to update the reference
5222 // field and, if both reference and referent are in the G1
5223 // heap, update the RSet for the referent.
5224 //
5225 // If the referent has not been forwarded then we have to keep
5226 // it alive by policy. Therefore we have copy the referent.
5227 //
5228 // If the reference field is in the G1 heap then we can push
5229 // on the PSS queue. When the queue is drained (after each
5230 // phase of reference processing) the object and it's followers
5231 // will be copied, the reference field set to point to the
5232 // new location, and the RSet updated. Otherwise we need to
5233 // use the the non-heap or metadata closures directly to copy
5234 // the referent object and update the pointer, while avoiding
5235 // updating the RSet.
5236
5237 if (_g1h->is_in_g1_reserved(p)) {
5238 _par_scan_state->push_on_queue(p);
5239 } else {
5240 assert(!Metaspace::contains((const void*)p),
5241 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5242 _copy_non_heap_obj_cl->do_oop(p);
5243 }
5244 }
5245 }
5246 };
5247
5248 // Serial drain queue closure. Called as the 'complete_gc'
5249 // closure for each discovered list in some of the
5250 // reference processing phases.
5251
5252 class G1STWDrainQueueClosure: public VoidClosure {
5253 protected:
5254 G1CollectedHeap* _g1h;
5255 G1ParScanThreadState* _par_scan_state;
5256
5257 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5258
5259 public:
5260 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5261 _g1h(g1h),
5262 _par_scan_state(pss)
5263 { }
5264
5265 void do_void() {
5266 G1ParScanThreadState* const pss = par_scan_state();
5267 pss->trim_queue();
5268 }
5269 };
5270
5271 // Parallel Reference Processing closures
5272
5273 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5274 // processing during G1 evacuation pauses.
5275
5276 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5277 private:
5278 G1CollectedHeap* _g1h;
5279 G1ParScanThreadStateSet* _pss;
5280 RefToScanQueueSet* _queues;
5281 WorkGang* _workers;
5282 uint _active_workers;
5283
5284 public:
5285 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5286 G1ParScanThreadStateSet* per_thread_states,
5287 WorkGang* workers,
5288 RefToScanQueueSet *task_queues,
5289 uint n_workers) :
5290 _g1h(g1h),
5291 _pss(per_thread_states),
5292 _queues(task_queues),
5293 _workers(workers),
5294 _active_workers(n_workers)
5295 {
5296 assert(n_workers > 0, "shouldn't call this otherwise");
5297 }
5298
5299 // Executes the given task using concurrent marking worker threads.
5300 virtual void execute(ProcessTask& task);
5301 virtual void execute(EnqueueTask& task);
5302 };
5303
5304 // Gang task for possibly parallel reference processing
5305
5306 class G1STWRefProcTaskProxy: public AbstractGangTask {
5307 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5308 ProcessTask& _proc_task;
5309 G1CollectedHeap* _g1h;
5310 G1ParScanThreadStateSet* _pss;
5311 RefToScanQueueSet* _task_queues;
5312 ParallelTaskTerminator* _terminator;
5313
5314 public:
5315 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5316 G1CollectedHeap* g1h,
5317 G1ParScanThreadStateSet* per_thread_states,
5318 RefToScanQueueSet *task_queues,
5319 ParallelTaskTerminator* terminator) :
5320 AbstractGangTask("Process reference objects in parallel"),
5321 _proc_task(proc_task),
5322 _g1h(g1h),
5323 _pss(per_thread_states),
5324 _task_queues(task_queues),
5325 _terminator(terminator)
5326 {}
5327
5328 virtual void work(uint worker_id) {
5329 // The reference processing task executed by a single worker.
5330 ResourceMark rm;
5331 HandleMark hm;
5332
5333 G1STWIsAliveClosure is_alive(_g1h);
5334
5335 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5336 pss->set_ref_processor(NULL);
5337
5338 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5339
5340 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5341
5342 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5343
5344 if (_g1h->collector_state()->during_initial_mark_pause()) {
5345 // We also need to mark copied objects.
5346 copy_non_heap_cl = ©_mark_non_heap_cl;
5347 }
5348
5349 // Keep alive closure.
5350 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5351
5352 // Complete GC closure
5353 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5354
5355 // Call the reference processing task's work routine.
5356 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5357
5358 // Note we cannot assert that the refs array is empty here as not all
5359 // of the processing tasks (specifically phase2 - pp2_work) execute
5360 // the complete_gc closure (which ordinarily would drain the queue) so
5361 // the queue may not be empty.
5362 }
5363 };
5364
5365 // Driver routine for parallel reference processing.
5366 // Creates an instance of the ref processing gang
5367 // task and has the worker threads execute it.
5368 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5369 assert(_workers != NULL, "Need parallel worker threads.");
5370
5371 ParallelTaskTerminator terminator(_active_workers, _queues);
5372 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5373
5374 _workers->run_task(&proc_task_proxy);
5375 }
5376
5377 // Gang task for parallel reference enqueueing.
5378
5379 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5380 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5381 EnqueueTask& _enq_task;
5382
5383 public:
5384 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5385 AbstractGangTask("Enqueue reference objects in parallel"),
5386 _enq_task(enq_task)
5387 { }
5388
5389 virtual void work(uint worker_id) {
5390 _enq_task.work(worker_id);
5391 }
5392 };
5393
5394 // Driver routine for parallel reference enqueueing.
5395 // Creates an instance of the ref enqueueing gang
5396 // task and has the worker threads execute it.
5397
5398 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5399 assert(_workers != NULL, "Need parallel worker threads.");
5400
5401 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5402
5403 _workers->run_task(&enq_task_proxy);
5404 }
5405
5406 // End of weak reference support closures
5407
5408 // Abstract task used to preserve (i.e. copy) any referent objects
5409 // that are in the collection set and are pointed to by reference
5410 // objects discovered by the CM ref processor.
5411
5412 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5413 protected:
5414 G1CollectedHeap* _g1h;
5415 G1ParScanThreadStateSet* _pss;
5416 RefToScanQueueSet* _queues;
5417 ParallelTaskTerminator _terminator;
5418 uint _n_workers;
5419
5420 public:
5421 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5422 AbstractGangTask("ParPreserveCMReferents"),
5423 _g1h(g1h),
5424 _pss(per_thread_states),
5425 _queues(task_queues),
5426 _terminator(workers, _queues),
5427 _n_workers(workers)
5428 { }
5429
5430 void work(uint worker_id) {
5431 ResourceMark rm;
5432 HandleMark hm;
5433
5434 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5435 pss->set_ref_processor(NULL);
5436 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5437
5438 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5439
5440 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5441
5442 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5443
5444 if (_g1h->collector_state()->during_initial_mark_pause()) {
5445 // We also need to mark copied objects.
5446 copy_non_heap_cl = ©_mark_non_heap_cl;
5447 }
5448
5449 // Is alive closure
5450 G1AlwaysAliveClosure always_alive(_g1h);
5451
5452 // Copying keep alive closure. Applied to referent objects that need
5453 // to be copied.
5454 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5455
5456 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5457
5458 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5459 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5460
5461 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5462 // So this must be true - but assert just in case someone decides to
5463 // change the worker ids.
5464 assert(worker_id < limit, "sanity");
5465 assert(!rp->discovery_is_atomic(), "check this code");
5466
5467 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5468 for (uint idx = worker_id; idx < limit; idx += stride) {
5469 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5470
5471 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5472 while (iter.has_next()) {
5473 // Since discovery is not atomic for the CM ref processor, we
5474 // can see some null referent objects.
5475 iter.load_ptrs(DEBUG_ONLY(true));
5476 oop ref = iter.obj();
5477
5478 // This will filter nulls.
5479 if (iter.is_referent_alive()) {
5480 iter.make_referent_alive();
5481 }
5482 iter.move_to_next();
5483 }
5484 }
5485
5486 // Drain the queue - which may cause stealing
5487 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5488 drain_queue.do_void();
5489 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5490 assert(pss->queue_is_empty(), "should be");
5491 }
5492 };
5493
5494 // Weak Reference processing during an evacuation pause (part 1).
5495 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5496 double ref_proc_start = os::elapsedTime();
5497
5498 ReferenceProcessor* rp = _ref_processor_stw;
5499 assert(rp->discovery_enabled(), "should have been enabled");
5500
5501 // Any reference objects, in the collection set, that were 'discovered'
5502 // by the CM ref processor should have already been copied (either by
5503 // applying the external root copy closure to the discovered lists, or
5504 // by following an RSet entry).
5505 //
5506 // But some of the referents, that are in the collection set, that these
5507 // reference objects point to may not have been copied: the STW ref
5508 // processor would have seen that the reference object had already
5509 // been 'discovered' and would have skipped discovering the reference,
5510 // but would not have treated the reference object as a regular oop.
5511 // As a result the copy closure would not have been applied to the
5512 // referent object.
5513 //
5514 // We need to explicitly copy these referent objects - the references
5515 // will be processed at the end of remarking.
5516 //
5517 // We also need to do this copying before we process the reference
5518 // objects discovered by the STW ref processor in case one of these
5519 // referents points to another object which is also referenced by an
5520 // object discovered by the STW ref processor.
5521
5522 uint no_of_gc_workers = workers()->active_workers();
5523
5524 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5525 per_thread_states,
5526 no_of_gc_workers,
5527 _task_queues);
5528
5529 workers()->run_task(&keep_cm_referents);
5530
5531 // Closure to test whether a referent is alive.
5532 G1STWIsAliveClosure is_alive(this);
5533
5534 // Even when parallel reference processing is enabled, the processing
5535 // of JNI refs is serial and performed serially by the current thread
5536 // rather than by a worker. The following PSS will be used for processing
5537 // JNI refs.
5538
5539 // Use only a single queue for this PSS.
5540 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5541 pss->set_ref_processor(NULL);
5542 assert(pss->queue_is_empty(), "pre-condition");
5543
5544 // We do not embed a reference processor in the copying/scanning
5545 // closures while we're actually processing the discovered
5546 // reference objects.
5547
5548 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss);
5549
5550 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5551
5552 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5553
5554 if (collector_state()->during_initial_mark_pause()) {
5555 // We also need to mark copied objects.
5556 copy_non_heap_cl = ©_mark_non_heap_cl;
5557 }
5558
5559 // Keep alive closure.
5560 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5561
5562 // Serial Complete GC closure
5563 G1STWDrainQueueClosure drain_queue(this, pss);
5564
5565 // Setup the soft refs policy...
5566 rp->setup_policy(false);
5567
5568 ReferenceProcessorStats stats;
5569 if (!rp->processing_is_mt()) {
5570 // Serial reference processing...
5571 stats = rp->process_discovered_references(&is_alive,
5572 &keep_alive,
5573 &drain_queue,
5574 NULL,
5575 _gc_timer_stw);
5576 } else {
5577 // Parallel reference processing
5578 assert(rp->num_q() == no_of_gc_workers, "sanity");
5579 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5580
5581 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5582 stats = rp->process_discovered_references(&is_alive,
5583 &keep_alive,
5584 &drain_queue,
5585 &par_task_executor,
5586 _gc_timer_stw);
5587 }
5588
5589 _gc_tracer_stw->report_gc_reference_stats(stats);
5590
5591 // We have completed copying any necessary live referent objects.
5592 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5593
5594 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5595 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5596 }
5597
5598 // Weak Reference processing during an evacuation pause (part 2).
5599 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5600 double ref_enq_start = os::elapsedTime();
5601
5602 ReferenceProcessor* rp = _ref_processor_stw;
5603 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5604
5605 // Now enqueue any remaining on the discovered lists on to
5606 // the pending list.
5607 if (!rp->processing_is_mt()) {
5608 // Serial reference processing...
5609 rp->enqueue_discovered_references();
5610 } else {
5611 // Parallel reference enqueueing
5612
5613 uint n_workers = workers()->active_workers();
5614
5615 assert(rp->num_q() == n_workers, "sanity");
5616 assert(n_workers <= rp->max_num_q(), "sanity");
5617
5618 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5619 rp->enqueue_discovered_references(&par_task_executor);
5620 }
5621
5622 rp->verify_no_references_recorded();
5623 assert(!rp->discovery_enabled(), "should have been disabled");
5624
5625 // FIXME
5626 // CM's reference processing also cleans up the string and symbol tables.
5627 // Should we do that here also? We could, but it is a serial operation
5628 // and could significantly increase the pause time.
5629
5630 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5631 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5632 }
5633
5634 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5635 _expand_heap_after_alloc_failure = true;
5636 _evacuation_failed = false;
5637
5638 // Should G1EvacuationFailureALot be in effect for this GC?
5639 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5640
5641 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5642
5643 // Disable the hot card cache.
5644 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5645 hot_card_cache->reset_hot_cache_claimed_index();
5646 hot_card_cache->set_use_cache(false);
5647
5648 const uint n_workers = workers()->active_workers();
5649
5650 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5651 double start_par_time_sec = os::elapsedTime();
5652 double end_par_time_sec;
5653
5654 {
5655 G1RootProcessor root_processor(this, n_workers);
5656 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5657 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5658 if (collector_state()->during_initial_mark_pause()) {
5659 ClassLoaderDataGraph::clear_claimed_marks();
5660 }
5661
5662 // The individual threads will set their evac-failure closures.
5663 if (PrintTerminationStats) {
5664 print_termination_stats_hdr(gclog_or_tty);
5665 }
5666
5667 workers()->run_task(&g1_par_task);
5668 end_par_time_sec = os::elapsedTime();
5669
5670 // Closing the inner scope will execute the destructor
5671 // for the G1RootProcessor object. We record the current
5672 // elapsed time before closing the scope so that time
5673 // taken for the destructor is NOT included in the
5674 // reported parallel time.
5675 }
5676
5677 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5678
5679 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5680 phase_times->record_par_time(par_time_ms);
5681
5682 double code_root_fixup_time_ms =
5683 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5684 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5685
5686 // Process any discovered reference objects - we have
5687 // to do this _before_ we retire the GC alloc regions
5688 // as we may have to copy some 'reachable' referent
5689 // objects (and their reachable sub-graphs) that were
5690 // not copied during the pause.
5691 process_discovered_references(per_thread_states);
5692
5693 if (G1StringDedup::is_enabled()) {
5694 double fixup_start = os::elapsedTime();
5695
5696 G1STWIsAliveClosure is_alive(this);
5697 G1KeepAliveClosure keep_alive(this);
5698 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5699
5700 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5701 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5702 }
5703
5704 _allocator->release_gc_alloc_regions(evacuation_info);
5705 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5706
5707 per_thread_states->flush();
5708
5709 record_obj_copy_mem_stats();
5710
5711 // Reset and re-enable the hot card cache.
5712 // Note the counts for the cards in the regions in the
5713 // collection set are reset when the collection set is freed.
5714 hot_card_cache->reset_hot_cache();
5715 hot_card_cache->set_use_cache(true);
5716
5717 purge_code_root_memory();
5718
5719 if (evacuation_failed()) {
5720 remove_self_forwarding_pointers();
5721
5722 // Reset the G1EvacuationFailureALot counters and flags
5723 // Note: the values are reset only when an actual
5724 // evacuation failure occurs.
5725 NOT_PRODUCT(reset_evacuation_should_fail();)
5726 }
5727
5728 // Enqueue any remaining references remaining on the STW
5729 // reference processor's discovered lists. We need to do
5730 // this after the card table is cleaned (and verified) as
5731 // the act of enqueueing entries on to the pending list
5732 // will log these updates (and dirty their associated
5733 // cards). We need these updates logged to update any
5734 // RSets.
5735 enqueue_discovered_references(per_thread_states);
5736
5737 redirty_logged_cards();
5738 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5739 }
5740
5741 void G1CollectedHeap::record_obj_copy_mem_stats() {
5742 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5743 create_g1_evac_summary(&_old_evac_stats));
5744 }
5745
5746 void G1CollectedHeap::free_region(HeapRegion* hr,
5747 FreeRegionList* free_list,
5748 bool par,
5749 bool locked) {
5750 assert(!hr->is_free(), "the region should not be free");
5751 assert(!hr->is_empty(), "the region should not be empty");
5752 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5753 assert(free_list != NULL, "pre-condition");
5754
5755 if (G1VerifyBitmaps) {
5756 MemRegion mr(hr->bottom(), hr->end());
5757 concurrent_mark()->clearRangePrevBitmap(mr);
5758 }
5759
5760 // Clear the card counts for this region.
5761 // Note: we only need to do this if the region is not young
5762 // (since we don't refine cards in young regions).
5763 if (!hr->is_young()) {
5764 _cg1r->hot_card_cache()->reset_card_counts(hr);
5765 }
5766 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5767 free_list->add_ordered(hr);
5768 }
5769
5770 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5771 FreeRegionList* free_list,
5772 bool par) {
5773 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5774 assert(free_list != NULL, "pre-condition");
5775
5776 size_t hr_capacity = hr->capacity();
5777 // We need to read this before we make the region non-humongous,
5778 // otherwise the information will be gone.
5779 uint last_index = hr->last_hc_index();
5780 hr->clear_humongous();
5781 free_region(hr, free_list, par);
5782
5783 uint i = hr->hrm_index() + 1;
5784 while (i < last_index) {
5785 HeapRegion* curr_hr = region_at(i);
5786 assert(curr_hr->is_continues_humongous(), "invariant");
5787 curr_hr->clear_humongous();
5788 free_region(curr_hr, free_list, par);
5789 i += 1;
5790 }
5791 }
5792
5793 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5794 const HeapRegionSetCount& humongous_regions_removed) {
5795 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5796 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5797 _old_set.bulk_remove(old_regions_removed);
5798 _humongous_set.bulk_remove(humongous_regions_removed);
5799 }
5800
5801 }
5802
5803 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5804 assert(list != NULL, "list can't be null");
5805 if (!list->is_empty()) {
5806 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5807 _hrm.insert_list_into_free_list(list);
5808 }
5809 }
5810
5811 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5812 decrease_used(bytes);
5813 }
5814
5815 class G1ParCleanupCTTask : public AbstractGangTask {
5816 G1SATBCardTableModRefBS* _ct_bs;
5817 G1CollectedHeap* _g1h;
5818 HeapRegion* volatile _su_head;
5819 public:
5820 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5821 G1CollectedHeap* g1h) :
5822 AbstractGangTask("G1 Par Cleanup CT Task"),
5823 _ct_bs(ct_bs), _g1h(g1h) { }
5824
5825 void work(uint worker_id) {
5826 HeapRegion* r;
5827 while (r = _g1h->pop_dirty_cards_region()) {
5828 clear_cards(r);
5829 }
5830 }
5831
5832 void clear_cards(HeapRegion* r) {
5833 // Cards of the survivors should have already been dirtied.
5834 if (!r->is_survivor()) {
5835 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5836 }
5837 }
5838 };
5839
5840 #ifndef PRODUCT
5841 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5842 G1CollectedHeap* _g1h;
5843 G1SATBCardTableModRefBS* _ct_bs;
5844 public:
5845 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5846 : _g1h(g1h), _ct_bs(ct_bs) { }
5847 virtual bool doHeapRegion(HeapRegion* r) {
5848 if (r->is_survivor()) {
5849 _g1h->verify_dirty_region(r);
5850 } else {
5851 _g1h->verify_not_dirty_region(r);
5852 }
5853 return false;
5854 }
5855 };
5856
5857 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5858 // All of the region should be clean.
5859 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5860 MemRegion mr(hr->bottom(), hr->end());
5861 ct_bs->verify_not_dirty_region(mr);
5862 }
5863
5864 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5865 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5866 // dirty allocated blocks as they allocate them. The thread that
5867 // retires each region and replaces it with a new one will do a
5868 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5869 // not dirty that area (one less thing to have to do while holding
5870 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5871 // is dirty.
5872 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5873 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5874 if (hr->is_young()) {
5875 ct_bs->verify_g1_young_region(mr);
5876 } else {
5877 ct_bs->verify_dirty_region(mr);
5878 }
5879 }
5880
5881 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5882 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5883 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5884 verify_dirty_region(hr);
5885 }
5886 }
5887
5888 void G1CollectedHeap::verify_dirty_young_regions() {
5889 verify_dirty_young_list(_young_list->first_region());
5890 }
5891
5892 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5893 HeapWord* tams, HeapWord* end) {
5894 guarantee(tams <= end,
5895 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5896 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5897 if (result < end) {
5898 gclog_or_tty->cr();
5899 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5900 bitmap_name, p2i(result));
5901 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5902 bitmap_name, p2i(tams), p2i(end));
5903 return false;
5904 }
5905 return true;
5906 }
5907
5908 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5909 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5910 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5911
5912 HeapWord* bottom = hr->bottom();
5913 HeapWord* ptams = hr->prev_top_at_mark_start();
5914 HeapWord* ntams = hr->next_top_at_mark_start();
5915 HeapWord* end = hr->end();
5916
5917 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5918
5919 bool res_n = true;
5920 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5921 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5922 // if we happen to be in that state.
5923 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5924 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5925 }
5926 if (!res_p || !res_n) {
5927 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5928 HR_FORMAT_PARAMS(hr));
5929 gclog_or_tty->print_cr("#### Caller: %s", caller);
5930 return false;
5931 }
5932 return true;
5933 }
5934
5935 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5936 if (!G1VerifyBitmaps) return;
5937
5938 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5939 }
5940
5941 class G1VerifyBitmapClosure : public HeapRegionClosure {
5942 private:
5943 const char* _caller;
5944 G1CollectedHeap* _g1h;
5945 bool _failures;
5946
5947 public:
5948 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5949 _caller(caller), _g1h(g1h), _failures(false) { }
5950
5951 bool failures() { return _failures; }
5952
5953 virtual bool doHeapRegion(HeapRegion* hr) {
5954 if (hr->is_continues_humongous()) return false;
5955
5956 bool result = _g1h->verify_bitmaps(_caller, hr);
5957 if (!result) {
5958 _failures = true;
5959 }
5960 return false;
5961 }
5962 };
5963
5964 void G1CollectedHeap::check_bitmaps(const char* caller) {
5965 if (!G1VerifyBitmaps) return;
5966
5967 G1VerifyBitmapClosure cl(caller, this);
5968 heap_region_iterate(&cl);
5969 guarantee(!cl.failures(), "bitmap verification");
5970 }
5971
5972 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5973 private:
5974 bool _failures;
5975 public:
5976 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5977
5978 virtual bool doHeapRegion(HeapRegion* hr) {
5979 uint i = hr->hrm_index();
5980 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5981 if (hr->is_humongous()) {
5982 if (hr->in_collection_set()) {
5983 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5984 _failures = true;
5985 return true;
5986 }
5987 if (cset_state.is_in_cset()) {
5988 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5989 _failures = true;
5990 return true;
5991 }
5992 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5993 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5994 _failures = true;
5995 return true;
5996 }
5997 } else {
5998 if (cset_state.is_humongous()) {
5999 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6000 _failures = true;
6001 return true;
6002 }
6003 if (hr->in_collection_set() != cset_state.is_in_cset()) {
6004 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6005 hr->in_collection_set(), cset_state.value(), i);
6006 _failures = true;
6007 return true;
6008 }
6009 if (cset_state.is_in_cset()) {
6010 if (hr->is_young() != (cset_state.is_young())) {
6011 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6012 hr->is_young(), cset_state.value(), i);
6013 _failures = true;
6014 return true;
6015 }
6016 if (hr->is_old() != (cset_state.is_old())) {
6017 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6018 hr->is_old(), cset_state.value(), i);
6019 _failures = true;
6020 return true;
6021 }
6022 }
6023 }
6024 return false;
6025 }
6026
6027 bool failures() const { return _failures; }
6028 };
6029
6030 bool G1CollectedHeap::check_cset_fast_test() {
6031 G1CheckCSetFastTableClosure cl;
6032 _hrm.iterate(&cl);
6033 return !cl.failures();
6034 }
6035 #endif // PRODUCT
6036
6037 void G1CollectedHeap::cleanUpCardTable() {
6038 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6039 double start = os::elapsedTime();
6040
6041 {
6042 // Iterate over the dirty cards region list.
6043 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6044
6045 workers()->run_task(&cleanup_task);
6046 #ifndef PRODUCT
6047 if (G1VerifyCTCleanup || VerifyAfterGC) {
6048 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6049 heap_region_iterate(&cleanup_verifier);
6050 }
6051 #endif
6052 }
6053
6054 double elapsed = os::elapsedTime() - start;
6055 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6056 }
6057
6058 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6059 size_t pre_used = 0;
6060 FreeRegionList local_free_list("Local List for CSet Freeing");
6061
6062 double young_time_ms = 0.0;
6063 double non_young_time_ms = 0.0;
6064
6065 // Since the collection set is a superset of the the young list,
6066 // all we need to do to clear the young list is clear its
6067 // head and length, and unlink any young regions in the code below
6068 _young_list->clear();
6069
6070 G1CollectorPolicy* policy = g1_policy();
6071
6072 double start_sec = os::elapsedTime();
6073 bool non_young = true;
6074
6075 HeapRegion* cur = cs_head;
6076 int age_bound = -1;
6077 size_t rs_lengths = 0;
6078
6079 while (cur != NULL) {
6080 assert(!is_on_master_free_list(cur), "sanity");
6081 if (non_young) {
6082 if (cur->is_young()) {
6083 double end_sec = os::elapsedTime();
6084 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6085 non_young_time_ms += elapsed_ms;
6086
6087 start_sec = os::elapsedTime();
6088 non_young = false;
6089 }
6090 } else {
6091 if (!cur->is_young()) {
6092 double end_sec = os::elapsedTime();
6093 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6094 young_time_ms += elapsed_ms;
6095
6096 start_sec = os::elapsedTime();
6097 non_young = true;
6098 }
6099 }
6100
6101 rs_lengths += cur->rem_set()->occupied_locked();
6102
6103 HeapRegion* next = cur->next_in_collection_set();
6104 assert(cur->in_collection_set(), "bad CS");
6105 cur->set_next_in_collection_set(NULL);
6106 clear_in_cset(cur);
6107
6108 if (cur->is_young()) {
6109 int index = cur->young_index_in_cset();
6110 assert(index != -1, "invariant");
6111 assert((uint) index < policy->young_cset_region_length(), "invariant");
6112 size_t words_survived = _surviving_young_words[index];
6113 cur->record_surv_words_in_group(words_survived);
6114
6115 // At this point the we have 'popped' cur from the collection set
6116 // (linked via next_in_collection_set()) but it is still in the
6117 // young list (linked via next_young_region()). Clear the
6118 // _next_young_region field.
6119 cur->set_next_young_region(NULL);
6120 } else {
6121 int index = cur->young_index_in_cset();
6122 assert(index == -1, "invariant");
6123 }
6124
6125 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6126 (!cur->is_young() && cur->young_index_in_cset() == -1),
6127 "invariant" );
6128
6129 if (!cur->evacuation_failed()) {
6130 MemRegion used_mr = cur->used_region();
6131
6132 // And the region is empty.
6133 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6134 pre_used += cur->used();
6135 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6136 } else {
6137 cur->uninstall_surv_rate_group();
6138 if (cur->is_young()) {
6139 cur->set_young_index_in_cset(-1);
6140 }
6141 cur->set_evacuation_failed(false);
6142 // The region is now considered to be old.
6143 cur->set_old();
6144 // Do some allocation statistics accounting. Regions that failed evacuation
6145 // are always made old, so there is no need to update anything in the young
6146 // gen statistics, but we need to update old gen statistics.
6147 size_t used_words = cur->marked_bytes() / HeapWordSize;
6148 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6149 _old_set.add(cur);
6150 evacuation_info.increment_collectionset_used_after(cur->used());
6151 }
6152 cur = next;
6153 }
6154
6155 evacuation_info.set_regions_freed(local_free_list.length());
6156 policy->record_max_rs_lengths(rs_lengths);
6157 policy->cset_regions_freed();
6158
6159 double end_sec = os::elapsedTime();
6160 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6161
6162 if (non_young) {
6163 non_young_time_ms += elapsed_ms;
6164 } else {
6165 young_time_ms += elapsed_ms;
6166 }
6167
6168 prepend_to_freelist(&local_free_list);
6169 decrement_summary_bytes(pre_used);
6170 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6171 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6172 }
6173
6174 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6175 private:
6176 FreeRegionList* _free_region_list;
6177 HeapRegionSet* _proxy_set;
6178 HeapRegionSetCount _humongous_regions_removed;
6179 size_t _freed_bytes;
6180 public:
6181
6182 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6183 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6184 }
6185
6186 virtual bool doHeapRegion(HeapRegion* r) {
6187 if (!r->is_starts_humongous()) {
6188 return false;
6189 }
6190
6191 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6192
6193 oop obj = (oop)r->bottom();
6194 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6195
6196 // The following checks whether the humongous object is live are sufficient.
6197 // The main additional check (in addition to having a reference from the roots
6198 // or the young gen) is whether the humongous object has a remembered set entry.
6199 //
6200 // A humongous object cannot be live if there is no remembered set for it
6201 // because:
6202 // - there can be no references from within humongous starts regions referencing
6203 // the object because we never allocate other objects into them.
6204 // (I.e. there are no intra-region references that may be missed by the
6205 // remembered set)
6206 // - as soon there is a remembered set entry to the humongous starts region
6207 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6208 // until the end of a concurrent mark.
6209 //
6210 // It is not required to check whether the object has been found dead by marking
6211 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6212 // all objects allocated during that time are considered live.
6213 // SATB marking is even more conservative than the remembered set.
6214 // So if at this point in the collection there is no remembered set entry,
6215 // nobody has a reference to it.
6216 // At the start of collection we flush all refinement logs, and remembered sets
6217 // are completely up-to-date wrt to references to the humongous object.
6218 //
6219 // Other implementation considerations:
6220 // - never consider object arrays at this time because they would pose
6221 // considerable effort for cleaning up the the remembered sets. This is
6222 // required because stale remembered sets might reference locations that
6223 // are currently allocated into.
6224 uint region_idx = r->hrm_index();
6225 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6226 !r->rem_set()->is_empty()) {
6227
6228 if (G1TraceEagerReclaimHumongousObjects) {
6229 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",
6230 region_idx,
6231 (size_t)obj->size() * HeapWordSize,
6232 p2i(r->bottom()),
6233 r->region_num(),
6234 r->rem_set()->occupied(),
6235 r->rem_set()->strong_code_roots_list_length(),
6236 next_bitmap->isMarked(r->bottom()),
6237 g1h->is_humongous_reclaim_candidate(region_idx),
6238 obj->is_typeArray()
6239 );
6240 }
6241
6242 return false;
6243 }
6244
6245 guarantee(obj->is_typeArray(),
6246 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6247 PTR_FORMAT " is not.",
6248 p2i(r->bottom())));
6249
6250 if (G1TraceEagerReclaimHumongousObjects) {
6251 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",
6252 region_idx,
6253 (size_t)obj->size() * HeapWordSize,
6254 p2i(r->bottom()),
6255 r->region_num(),
6256 r->rem_set()->occupied(),
6257 r->rem_set()->strong_code_roots_list_length(),
6258 next_bitmap->isMarked(r->bottom()),
6259 g1h->is_humongous_reclaim_candidate(region_idx),
6260 obj->is_typeArray()
6261 );
6262 }
6263 // Need to clear mark bit of the humongous object if already set.
6264 if (next_bitmap->isMarked(r->bottom())) {
6265 next_bitmap->clear(r->bottom());
6266 }
6267 _freed_bytes += r->used();
6268 r->set_containing_set(NULL);
6269 _humongous_regions_removed.increment(1u, r->capacity());
6270 g1h->free_humongous_region(r, _free_region_list, false);
6271
6272 return false;
6273 }
6274
6275 HeapRegionSetCount& humongous_free_count() {
6276 return _humongous_regions_removed;
6277 }
6278
6279 size_t bytes_freed() const {
6280 return _freed_bytes;
6281 }
6282
6283 size_t humongous_reclaimed() const {
6284 return _humongous_regions_removed.length();
6285 }
6286 };
6287
6288 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6289 assert_at_safepoint(true);
6290
6291 if (!G1EagerReclaimHumongousObjects ||
6292 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6293 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6294 return;
6295 }
6296
6297 double start_time = os::elapsedTime();
6298
6299 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6300
6301 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6302 heap_region_iterate(&cl);
6303
6304 HeapRegionSetCount empty_set;
6305 remove_from_old_sets(empty_set, cl.humongous_free_count());
6306
6307 G1HRPrinter* hrp = hr_printer();
6308 if (hrp->is_active()) {
6309 FreeRegionListIterator iter(&local_cleanup_list);
6310 while (iter.more_available()) {
6311 HeapRegion* hr = iter.get_next();
6312 hrp->cleanup(hr);
6313 }
6314 }
6315
6316 prepend_to_freelist(&local_cleanup_list);
6317 decrement_summary_bytes(cl.bytes_freed());
6318
6319 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6320 cl.humongous_reclaimed());
6321 }
6322
6323 // This routine is similar to the above but does not record
6324 // any policy statistics or update free lists; we are abandoning
6325 // the current incremental collection set in preparation of a
6326 // full collection. After the full GC we will start to build up
6327 // the incremental collection set again.
6328 // This is only called when we're doing a full collection
6329 // and is immediately followed by the tearing down of the young list.
6330
6331 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6332 HeapRegion* cur = cs_head;
6333
6334 while (cur != NULL) {
6335 HeapRegion* next = cur->next_in_collection_set();
6336 assert(cur->in_collection_set(), "bad CS");
6337 cur->set_next_in_collection_set(NULL);
6338 clear_in_cset(cur);
6339 cur->set_young_index_in_cset(-1);
6340 cur = next;
6341 }
6342 }
6343
6344 void G1CollectedHeap::set_free_regions_coming() {
6345 if (G1ConcRegionFreeingVerbose) {
6346 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6347 "setting free regions coming");
6348 }
6349
6350 assert(!free_regions_coming(), "pre-condition");
6351 _free_regions_coming = true;
6352 }
6353
6354 void G1CollectedHeap::reset_free_regions_coming() {
6355 assert(free_regions_coming(), "pre-condition");
6356
6357 {
6358 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6359 _free_regions_coming = false;
6360 SecondaryFreeList_lock->notify_all();
6361 }
6362
6363 if (G1ConcRegionFreeingVerbose) {
6364 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6365 "reset free regions coming");
6366 }
6367 }
6368
6369 void G1CollectedHeap::wait_while_free_regions_coming() {
6370 // Most of the time we won't have to wait, so let's do a quick test
6371 // first before we take the lock.
6372 if (!free_regions_coming()) {
6373 return;
6374 }
6375
6376 if (G1ConcRegionFreeingVerbose) {
6377 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6378 "waiting for free regions");
6379 }
6380
6381 {
6382 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6383 while (free_regions_coming()) {
6384 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6385 }
6386 }
6387
6388 if (G1ConcRegionFreeingVerbose) {
6389 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6390 "done waiting for free regions");
6391 }
6392 }
6393
6394 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6395 return _allocator->is_retained_old_region(hr);
6396 }
6397
6398 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6399 _young_list->push_region(hr);
6400 }
6401
6402 class NoYoungRegionsClosure: public HeapRegionClosure {
6403 private:
6404 bool _success;
6405 public:
6406 NoYoungRegionsClosure() : _success(true) { }
6407 bool doHeapRegion(HeapRegion* r) {
6408 if (r->is_young()) {
6409 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6410 p2i(r->bottom()), p2i(r->end()));
6411 _success = false;
6412 }
6413 return false;
6414 }
6415 bool success() { return _success; }
6416 };
6417
6418 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6419 bool ret = _young_list->check_list_empty(check_sample);
6420
6421 if (check_heap) {
6422 NoYoungRegionsClosure closure;
6423 heap_region_iterate(&closure);
6424 ret = ret && closure.success();
6425 }
6426
6427 return ret;
6428 }
6429
6430 class TearDownRegionSetsClosure : public HeapRegionClosure {
6431 private:
6432 HeapRegionSet *_old_set;
6433
6434 public:
6435 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6436
6437 bool doHeapRegion(HeapRegion* r) {
6438 if (r->is_old()) {
6439 _old_set->remove(r);
6440 } else {
6441 // We ignore free regions, we'll empty the free list afterwards.
6442 // We ignore young regions, we'll empty the young list afterwards.
6443 // We ignore humongous regions, we're not tearing down the
6444 // humongous regions set.
6445 assert(r->is_free() || r->is_young() || r->is_humongous(),
6446 "it cannot be another type");
6447 }
6448 return false;
6449 }
6450
6451 ~TearDownRegionSetsClosure() {
6452 assert(_old_set->is_empty(), "post-condition");
6453 }
6454 };
6455
6456 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6457 assert_at_safepoint(true /* should_be_vm_thread */);
6458
6459 if (!free_list_only) {
6460 TearDownRegionSetsClosure cl(&_old_set);
6461 heap_region_iterate(&cl);
6462
6463 // Note that emptying the _young_list is postponed and instead done as
6464 // the first step when rebuilding the regions sets again. The reason for
6465 // this is that during a full GC string deduplication needs to know if
6466 // a collected region was young or old when the full GC was initiated.
6467 }
6468 _hrm.remove_all_free_regions();
6469 }
6470
6471 void G1CollectedHeap::increase_used(size_t bytes) {
6472 _summary_bytes_used += bytes;
6473 }
6474
6475 void G1CollectedHeap::decrease_used(size_t bytes) {
6476 assert(_summary_bytes_used >= bytes,
6477 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6478 _summary_bytes_used, bytes));
6479 _summary_bytes_used -= bytes;
6480 }
6481
6482 void G1CollectedHeap::set_used(size_t bytes) {
6483 _summary_bytes_used = bytes;
6484 }
6485
6486 class RebuildRegionSetsClosure : public HeapRegionClosure {
6487 private:
6488 bool _free_list_only;
6489 HeapRegionSet* _old_set;
6490 HeapRegionManager* _hrm;
6491 size_t _total_used;
6492
6493 public:
6494 RebuildRegionSetsClosure(bool free_list_only,
6495 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6496 _free_list_only(free_list_only),
6497 _old_set(old_set), _hrm(hrm), _total_used(0) {
6498 assert(_hrm->num_free_regions() == 0, "pre-condition");
6499 if (!free_list_only) {
6500 assert(_old_set->is_empty(), "pre-condition");
6501 }
6502 }
6503
6504 bool doHeapRegion(HeapRegion* r) {
6505 if (r->is_continues_humongous()) {
6506 return false;
6507 }
6508
6509 if (r->is_empty()) {
6510 // Add free regions to the free list
6511 r->set_free();
6512 r->set_allocation_context(AllocationContext::system());
6513 _hrm->insert_into_free_list(r);
6514 } else if (!_free_list_only) {
6515 assert(!r->is_young(), "we should not come across young regions");
6516
6517 if (r->is_humongous()) {
6518 // We ignore humongous regions. We left the humongous set unchanged.
6519 } else {
6520 // Objects that were compacted would have ended up on regions
6521 // that were previously old or free. Archive regions (which are
6522 // old) will not have been touched.
6523 assert(r->is_free() || r->is_old(), "invariant");
6524 // We now consider them old, so register as such. Leave
6525 // archive regions set that way, however, while still adding
6526 // them to the old set.
6527 if (!r->is_archive()) {
6528 r->set_old();
6529 }
6530 _old_set->add(r);
6531 }
6532 _total_used += r->used();
6533 }
6534
6535 return false;
6536 }
6537
6538 size_t total_used() {
6539 return _total_used;
6540 }
6541 };
6542
6543 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6544 assert_at_safepoint(true /* should_be_vm_thread */);
6545
6546 if (!free_list_only) {
6547 _young_list->empty_list();
6548 }
6549
6550 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6551 heap_region_iterate(&cl);
6552
6553 if (!free_list_only) {
6554 set_used(cl.total_used());
6555 if (_archive_allocator != NULL) {
6556 _archive_allocator->clear_used();
6557 }
6558 }
6559 assert(used_unlocked() == recalculate_used(),
6560 err_msg("inconsistent used_unlocked(), "
6561 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6562 used_unlocked(), recalculate_used()));
6563 }
6564
6565 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6566 _refine_cte_cl->set_concurrent(concurrent);
6567 }
6568
6569 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6570 HeapRegion* hr = heap_region_containing(p);
6571 return hr->is_in(p);
6572 }
6573
6574 // Methods for the mutator alloc region
6575
6576 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6577 bool force) {
6578 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6579 assert(!force || g1_policy()->can_expand_young_list(),
6580 "if force is true we should be able to expand the young list");
6581 bool young_list_full = g1_policy()->is_young_list_full();
6582 if (force || !young_list_full) {
6583 HeapRegion* new_alloc_region = new_region(word_size,
6584 false /* is_old */,
6585 false /* do_expand */);
6586 if (new_alloc_region != NULL) {
6587 set_region_short_lived_locked(new_alloc_region);
6588 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6589 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6590 return new_alloc_region;
6591 }
6592 }
6593 return NULL;
6594 }
6595
6596 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6597 size_t allocated_bytes) {
6598 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6599 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6600
6601 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6602 increase_used(allocated_bytes);
6603 _hr_printer.retire(alloc_region);
6604 // We update the eden sizes here, when the region is retired,
6605 // instead of when it's allocated, since this is the point that its
6606 // used space has been recored in _summary_bytes_used.
6607 g1mm()->update_eden_size();
6608 }
6609
6610 // Methods for the GC alloc regions
6611
6612 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6613 uint count,
6614 InCSetState dest) {
6615 assert(FreeList_lock->owned_by_self(), "pre-condition");
6616
6617 if (count < g1_policy()->max_regions(dest)) {
6618 const bool is_survivor = (dest.is_young());
6619 HeapRegion* new_alloc_region = new_region(word_size,
6620 !is_survivor,
6621 true /* do_expand */);
6622 if (new_alloc_region != NULL) {
6623 // We really only need to do this for old regions given that we
6624 // should never scan survivors. But it doesn't hurt to do it
6625 // for survivors too.
6626 new_alloc_region->record_timestamp();
6627 if (is_survivor) {
6628 new_alloc_region->set_survivor();
6629 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6630 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6631 } else {
6632 new_alloc_region->set_old();
6633 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6634 check_bitmaps("Old Region Allocation", new_alloc_region);
6635 }
6636 bool during_im = collector_state()->during_initial_mark_pause();
6637 new_alloc_region->note_start_of_copying(during_im);
6638 return new_alloc_region;
6639 }
6640 }
6641 return NULL;
6642 }
6643
6644 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6645 size_t allocated_bytes,
6646 InCSetState dest) {
6647 bool during_im = collector_state()->during_initial_mark_pause();
6648 alloc_region->note_end_of_copying(during_im);
6649 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6650 if (dest.is_young()) {
6651 young_list()->add_survivor_region(alloc_region);
6652 } else {
6653 _old_set.add(alloc_region);
6654 }
6655 _hr_printer.retire(alloc_region);
6656 }
6657
6658 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6659 bool expanded = false;
6660 uint index = _hrm.find_highest_free(&expanded);
6661
6662 if (index != G1_NO_HRM_INDEX) {
6663 if (expanded) {
6664 ergo_verbose1(ErgoHeapSizing,
6665 "attempt heap expansion",
6666 ergo_format_reason("requested address range outside heap bounds")
6667 ergo_format_byte("region size"),
6668 HeapRegion::GrainWords * HeapWordSize);
6669 }
6670 _hrm.allocate_free_regions_starting_at(index, 1);
6671 return region_at(index);
6672 }
6673 return NULL;
6674 }
6675
6676 // Heap region set verification
6677
6678 class VerifyRegionListsClosure : public HeapRegionClosure {
6679 private:
6680 HeapRegionSet* _old_set;
6681 HeapRegionSet* _humongous_set;
6682 HeapRegionManager* _hrm;
6683
6684 public:
6685 HeapRegionSetCount _old_count;
6686 HeapRegionSetCount _humongous_count;
6687 HeapRegionSetCount _free_count;
6688
6689 VerifyRegionListsClosure(HeapRegionSet* old_set,
6690 HeapRegionSet* humongous_set,
6691 HeapRegionManager* hrm) :
6692 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6693 _old_count(), _humongous_count(), _free_count(){ }
6694
6695 bool doHeapRegion(HeapRegion* hr) {
6696 if (hr->is_continues_humongous()) {
6697 return false;
6698 }
6699
6700 if (hr->is_young()) {
6701 // TODO
6702 } else if (hr->is_starts_humongous()) {
6703 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6704 _humongous_count.increment(1u, hr->capacity());
6705 } else if (hr->is_empty()) {
6706 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6707 _free_count.increment(1u, hr->capacity());
6708 } else if (hr->is_old()) {
6709 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6710 _old_count.increment(1u, hr->capacity());
6711 } else {
6712 // There are no other valid region types. Check for one invalid
6713 // one we can identify: pinned without old or humongous set.
6714 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6715 ShouldNotReachHere();
6716 }
6717 return false;
6718 }
6719
6720 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6721 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6722 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6723 old_set->total_capacity_bytes(), _old_count.capacity()));
6724
6725 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6726 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6727 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6728
6729 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()));
6730 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6731 free_list->total_capacity_bytes(), _free_count.capacity()));
6732 }
6733 };
6734
6735 void G1CollectedHeap::verify_region_sets() {
6736 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6737
6738 // First, check the explicit lists.
6739 _hrm.verify();
6740 {
6741 // Given that a concurrent operation might be adding regions to
6742 // the secondary free list we have to take the lock before
6743 // verifying it.
6744 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6745 _secondary_free_list.verify_list();
6746 }
6747
6748 // If a concurrent region freeing operation is in progress it will
6749 // be difficult to correctly attributed any free regions we come
6750 // across to the correct free list given that they might belong to
6751 // one of several (free_list, secondary_free_list, any local lists,
6752 // etc.). So, if that's the case we will skip the rest of the
6753 // verification operation. Alternatively, waiting for the concurrent
6754 // operation to complete will have a non-trivial effect on the GC's
6755 // operation (no concurrent operation will last longer than the
6756 // interval between two calls to verification) and it might hide
6757 // any issues that we would like to catch during testing.
6758 if (free_regions_coming()) {
6759 return;
6760 }
6761
6762 // Make sure we append the secondary_free_list on the free_list so
6763 // that all free regions we will come across can be safely
6764 // attributed to the free_list.
6765 append_secondary_free_list_if_not_empty_with_lock();
6766
6767 // Finally, make sure that the region accounting in the lists is
6768 // consistent with what we see in the heap.
6769
6770 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6771 heap_region_iterate(&cl);
6772 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6773 }
6774
6775 // Optimized nmethod scanning
6776
6777 class RegisterNMethodOopClosure: public OopClosure {
6778 G1CollectedHeap* _g1h;
6779 nmethod* _nm;
6780
6781 template <class T> void do_oop_work(T* p) {
6782 T heap_oop = oopDesc::load_heap_oop(p);
6783 if (!oopDesc::is_null(heap_oop)) {
6784 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6785 HeapRegion* hr = _g1h->heap_region_containing(obj);
6786 assert(!hr->is_continues_humongous(),
6787 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6788 " starting at " HR_FORMAT,
6789 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6790
6791 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6792 hr->add_strong_code_root_locked(_nm);
6793 }
6794 }
6795
6796 public:
6797 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6798 _g1h(g1h), _nm(nm) {}
6799
6800 void do_oop(oop* p) { do_oop_work(p); }
6801 void do_oop(narrowOop* p) { do_oop_work(p); }
6802 };
6803
6804 class UnregisterNMethodOopClosure: public OopClosure {
6805 G1CollectedHeap* _g1h;
6806 nmethod* _nm;
6807
6808 template <class T> void do_oop_work(T* p) {
6809 T heap_oop = oopDesc::load_heap_oop(p);
6810 if (!oopDesc::is_null(heap_oop)) {
6811 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6812 HeapRegion* hr = _g1h->heap_region_containing(obj);
6813 assert(!hr->is_continues_humongous(),
6814 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6815 " starting at " HR_FORMAT,
6816 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6817
6818 hr->remove_strong_code_root(_nm);
6819 }
6820 }
6821
6822 public:
6823 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6824 _g1h(g1h), _nm(nm) {}
6825
6826 void do_oop(oop* p) { do_oop_work(p); }
6827 void do_oop(narrowOop* p) { do_oop_work(p); }
6828 };
6829
6830 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6831 CollectedHeap::register_nmethod(nm);
6832
6833 guarantee(nm != NULL, "sanity");
6834 RegisterNMethodOopClosure reg_cl(this, nm);
6835 nm->oops_do(®_cl);
6836 }
6837
6838 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6839 CollectedHeap::unregister_nmethod(nm);
6840
6841 guarantee(nm != NULL, "sanity");
6842 UnregisterNMethodOopClosure reg_cl(this, nm);
6843 nm->oops_do(®_cl, true);
6844 }
6845
6846 void G1CollectedHeap::purge_code_root_memory() {
6847 double purge_start = os::elapsedTime();
6848 G1CodeRootSet::purge();
6849 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6850 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6851 }
6852
6853 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6854 G1CollectedHeap* _g1h;
6855
6856 public:
6857 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6858 _g1h(g1h) {}
6859
6860 void do_code_blob(CodeBlob* cb) {
6861 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6862 if (nm == NULL) {
6863 return;
6864 }
6865
6866 if (ScavengeRootsInCode) {
6867 _g1h->register_nmethod(nm);
6868 }
6869 }
6870 };
6871
6872 void G1CollectedHeap::rebuild_strong_code_roots() {
6873 RebuildStrongCodeRootClosure blob_cl(this);
6874 CodeCache::blobs_do(&blob_cl);
6875 }