1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "memory/allocation.hpp"
65 #include "memory/iterator.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72 #include "utilities/stack.inline.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
202 "incorrectly tagged (y: %d, surv: %d)",
203 p2i(curr->bottom()), p2i(curr->end()),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 p2i(curr->prev_top_at_mark_start()),
333 p2i(curr->next_top_at_mark_start()),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_pinned();
410 }
411
412 // Private methods.
413
414 HeapRegion*
415 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
416 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
417 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
418 if (!_secondary_free_list.is_empty()) {
419 if (G1ConcRegionFreeingVerbose) {
420 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
421 "secondary_free_list has %u entries",
422 _secondary_free_list.length());
423 }
424 // It looks as if there are free regions available on the
425 // secondary_free_list. Let's move them to the free_list and try
426 // again to allocate from it.
427 append_secondary_free_list();
428
429 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
430 "empty we should have moved at least one entry to the free_list");
431 HeapRegion* res = _hrm.allocate_free_region(is_old);
432 if (G1ConcRegionFreeingVerbose) {
433 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
434 "allocated " HR_FORMAT " from secondary_free_list",
435 HR_FORMAT_PARAMS(res));
436 }
437 return res;
438 }
439
440 // Wait here until we get notified either when (a) there are no
441 // more free regions coming or (b) some regions have been moved on
442 // the secondary_free_list.
443 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
444 }
445
446 if (G1ConcRegionFreeingVerbose) {
447 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
448 "could not allocate from secondary_free_list");
449 }
450 return NULL;
451 }
452
453 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
454 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
455 "the only time we use this to allocate a humongous region is "
456 "when we are allocating a single humongous region");
457
458 HeapRegion* res;
459 if (G1StressConcRegionFreeing) {
460 if (!_secondary_free_list.is_empty()) {
461 if (G1ConcRegionFreeingVerbose) {
462 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
463 "forced to look at the secondary_free_list");
464 }
465 res = new_region_try_secondary_free_list(is_old);
466 if (res != NULL) {
467 return res;
468 }
469 }
470 }
471
472 res = _hrm.allocate_free_region(is_old);
473
474 if (res == NULL) {
475 if (G1ConcRegionFreeingVerbose) {
476 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
477 "res == NULL, trying the secondary_free_list");
478 }
479 res = new_region_try_secondary_free_list(is_old);
480 }
481 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
482 // Currently, only attempts to allocate GC alloc regions set
483 // do_expand to true. So, we should only reach here during a
484 // safepoint. If this assumption changes we might have to
485 // reconsider the use of _expand_heap_after_alloc_failure.
486 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
487
488 ergo_verbose1(ErgoHeapSizing,
489 "attempt heap expansion",
490 ergo_format_reason("region allocation request failed")
491 ergo_format_byte("allocation request"),
492 word_size * HeapWordSize);
493 if (expand(word_size * HeapWordSize)) {
494 // Given that expand() succeeded in expanding the heap, and we
495 // always expand the heap by an amount aligned to the heap
496 // region size, the free list should in theory not be empty.
497 // In either case allocate_free_region() will check for NULL.
498 res = _hrm.allocate_free_region(is_old);
499 } else {
500 _expand_heap_after_alloc_failure = false;
501 }
502 }
503 return res;
504 }
505
506 HeapWord*
507 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
508 uint num_regions,
509 size_t word_size,
510 AllocationContext_t context) {
511 assert(first != G1_NO_HRM_INDEX, "pre-condition");
512 assert(is_humongous(word_size), "word_size should be humongous");
513 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
514
515 // Index of last region in the series + 1.
516 uint last = first + num_regions;
517
518 // We need to initialize the region(s) we just discovered. This is
519 // a bit tricky given that it can happen concurrently with
520 // refinement threads refining cards on these regions and
521 // potentially wanting to refine the BOT as they are scanning
522 // those cards (this can happen shortly after a cleanup; see CR
523 // 6991377). So we have to set up the region(s) carefully and in
524 // a specific order.
525
526 // The word size sum of all the regions we will allocate.
527 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
528 assert(word_size <= word_size_sum, "sanity");
529
530 // This will be the "starts humongous" region.
531 HeapRegion* first_hr = region_at(first);
532 // The header of the new object will be placed at the bottom of
533 // the first region.
534 HeapWord* new_obj = first_hr->bottom();
535 // This will be the new end of the first region in the series that
536 // should also match the end of the last region in the series.
537 HeapWord* new_end = new_obj + word_size_sum;
538 // This will be the new top of the first region that will reflect
539 // this allocation.
540 HeapWord* new_top = new_obj + word_size;
541
542 // First, we need to zero the header of the space that we will be
543 // allocating. When we update top further down, some refinement
544 // threads might try to scan the region. By zeroing the header we
545 // ensure that any thread that will try to scan the region will
546 // come across the zero klass word and bail out.
547 //
548 // NOTE: It would not have been correct to have used
549 // CollectedHeap::fill_with_object() and make the space look like
550 // an int array. The thread that is doing the allocation will
551 // later update the object header to a potentially different array
552 // type and, for a very short period of time, the klass and length
553 // fields will be inconsistent. This could cause a refinement
554 // thread to calculate the object size incorrectly.
555 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
556
557 // We will set up the first region as "starts humongous". This
558 // will also update the BOT covering all the regions to reflect
559 // that there is a single object that starts at the bottom of the
560 // first region.
561 first_hr->set_starts_humongous(new_top, new_end);
562 first_hr->set_allocation_context(context);
563 // Then, if there are any, we will set up the "continues
564 // humongous" regions.
565 HeapRegion* hr = NULL;
566 for (uint i = first + 1; i < last; ++i) {
567 hr = region_at(i);
568 hr->set_continues_humongous(first_hr);
569 hr->set_allocation_context(context);
570 }
571 // If we have "continues humongous" regions (hr != NULL), then the
572 // end of the last one should match new_end.
573 assert(hr == NULL || hr->end() == new_end, "sanity");
574
575 // Up to this point no concurrent thread would have been able to
576 // do any scanning on any region in this series. All the top
577 // fields still point to bottom, so the intersection between
578 // [bottom,top] and [card_start,card_end] will be empty. Before we
579 // update the top fields, we'll do a storestore to make sure that
580 // no thread sees the update to top before the zeroing of the
581 // object header and the BOT initialization.
582 OrderAccess::storestore();
583
584 // Now that the BOT and the object header have been initialized,
585 // we can update top of the "starts humongous" region.
586 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
587 "new_top should be in this region");
588 first_hr->set_top(new_top);
589 if (_hr_printer.is_active()) {
590 HeapWord* bottom = first_hr->bottom();
591 HeapWord* end = first_hr->orig_end();
592 if ((first + 1) == last) {
593 // the series has a single humongous region
594 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
595 } else {
596 // the series has more than one humongous regions
597 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
598 }
599 }
600
601 // Now, we will update the top fields of the "continues humongous"
602 // regions. The reason we need to do this is that, otherwise,
603 // these regions would look empty and this will confuse parts of
604 // G1. For example, the code that looks for a consecutive number
605 // of empty regions will consider them empty and try to
606 // re-allocate them. We can extend is_empty() to also include
607 // !is_continues_humongous(), but it is easier to just update the top
608 // fields here. The way we set top for all regions (i.e., top ==
609 // end for all regions but the last one, top == new_top for the
610 // last one) is actually used when we will free up the humongous
611 // region in free_humongous_region().
612 hr = NULL;
613 for (uint i = first + 1; i < last; ++i) {
614 hr = region_at(i);
615 if ((i + 1) == last) {
616 // last continues humongous region
617 assert(hr->bottom() < new_top && new_top <= hr->end(),
618 "new_top should fall on this region");
619 hr->set_top(new_top);
620 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
621 } else {
622 // not last one
623 assert(new_top > hr->end(), "new_top should be above this region");
624 hr->set_top(hr->end());
625 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
626 }
627 }
628 // If we have continues humongous regions (hr != NULL), then the
629 // end of the last one should match new_end and its top should
630 // match new_top.
631 assert(hr == NULL ||
632 (hr->end() == new_end && hr->top() == new_top), "sanity");
633 check_bitmaps("Humongous Region Allocation", first_hr);
634
635 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
636 increase_used(first_hr->used());
637 _humongous_set.add(first_hr);
638
639 return new_obj;
640 }
641
642 // If could fit into free regions w/o expansion, try.
643 // Otherwise, if can expand, do so.
644 // Otherwise, if using ex regions might help, try with ex given back.
645 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
647
648 verify_region_sets_optional();
649
650 uint first = G1_NO_HRM_INDEX;
651 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
652
653 if (obj_regions == 1) {
654 // Only one region to allocate, try to use a fast path by directly allocating
655 // from the free lists. Do not try to expand here, we will potentially do that
656 // later.
657 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
658 if (hr != NULL) {
659 first = hr->hrm_index();
660 }
661 } else {
662 // We can't allocate humongous regions spanning more than one region while
663 // cleanupComplete() is running, since some of the regions we find to be
664 // empty might not yet be added to the free list. It is not straightforward
665 // to know in which list they are on so that we can remove them. We only
666 // need to do this if we need to allocate more than one region to satisfy the
667 // current humongous allocation request. If we are only allocating one region
668 // we use the one-region region allocation code (see above), that already
669 // potentially waits for regions from the secondary free list.
670 wait_while_free_regions_coming();
671 append_secondary_free_list_if_not_empty_with_lock();
672
673 // Policy: Try only empty regions (i.e. already committed first). Maybe we
674 // are lucky enough to find some.
675 first = _hrm.find_contiguous_only_empty(obj_regions);
676 if (first != G1_NO_HRM_INDEX) {
677 _hrm.allocate_free_regions_starting_at(first, obj_regions);
678 }
679 }
680
681 if (first == G1_NO_HRM_INDEX) {
682 // Policy: We could not find enough regions for the humongous object in the
683 // free list. Look through the heap to find a mix of free and uncommitted regions.
684 // If so, try expansion.
685 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
686 if (first != G1_NO_HRM_INDEX) {
687 // We found something. Make sure these regions are committed, i.e. expand
688 // the heap. Alternatively we could do a defragmentation GC.
689 ergo_verbose1(ErgoHeapSizing,
690 "attempt heap expansion",
691 ergo_format_reason("humongous allocation request failed")
692 ergo_format_byte("allocation request"),
693 word_size * HeapWordSize);
694
695 _hrm.expand_at(first, obj_regions);
696 g1_policy()->record_new_heap_size(num_regions());
697
698 #ifdef ASSERT
699 for (uint i = first; i < first + obj_regions; ++i) {
700 HeapRegion* hr = region_at(i);
701 assert(hr->is_free(), "sanity");
702 assert(hr->is_empty(), "sanity");
703 assert(is_on_master_free_list(hr), "sanity");
704 }
705 #endif
706 _hrm.allocate_free_regions_starting_at(first, obj_regions);
707 } else {
708 // Policy: Potentially trigger a defragmentation GC.
709 }
710 }
711
712 HeapWord* result = NULL;
713 if (first != G1_NO_HRM_INDEX) {
714 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
715 word_size, context);
716 assert(result != NULL, "it should always return a valid result");
717
718 // A successful humongous object allocation changes the used space
719 // information of the old generation so we need to recalculate the
720 // sizes and update the jstat counters here.
721 g1mm()->update_sizes();
722 }
723
724 verify_region_sets_optional();
725
726 return result;
727 }
728
729 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
730 assert_heap_not_locked_and_not_at_safepoint();
731 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
732
733 uint dummy_gc_count_before;
734 uint dummy_gclocker_retry_count = 0;
735 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
736 }
737
738 HeapWord*
739 G1CollectedHeap::mem_allocate(size_t word_size,
740 bool* gc_overhead_limit_was_exceeded) {
741 assert_heap_not_locked_and_not_at_safepoint();
742
743 // Loop until the allocation is satisfied, or unsatisfied after GC.
744 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
745 uint gc_count_before;
746
747 HeapWord* result = NULL;
748 if (!is_humongous(word_size)) {
749 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
750 } else {
751 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
752 }
753 if (result != NULL) {
754 return result;
755 }
756
757 // Create the garbage collection operation...
758 VM_G1CollectForAllocation op(gc_count_before, word_size);
759 op.set_allocation_context(AllocationContext::current());
760
761 // ...and get the VM thread to execute it.
762 VMThread::execute(&op);
763
764 if (op.prologue_succeeded() && op.pause_succeeded()) {
765 // If the operation was successful we'll return the result even
766 // if it is NULL. If the allocation attempt failed immediately
767 // after a Full GC, it's unlikely we'll be able to allocate now.
768 HeapWord* result = op.result();
769 if (result != NULL && !is_humongous(word_size)) {
770 // Allocations that take place on VM operations do not do any
771 // card dirtying and we have to do it here. We only have to do
772 // this for non-humongous allocations, though.
773 dirty_young_block(result, word_size);
774 }
775 return result;
776 } else {
777 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
778 return NULL;
779 }
780 assert(op.result() == NULL,
781 "the result should be NULL if the VM op did not succeed");
782 }
783
784 // Give a warning if we seem to be looping forever.
785 if ((QueuedAllocationWarningCount > 0) &&
786 (try_count % QueuedAllocationWarningCount == 0)) {
787 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
788 }
789 }
790
791 ShouldNotReachHere();
792 return NULL;
793 }
794
795 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
796 AllocationContext_t context,
797 uint* gc_count_before_ret,
798 uint* gclocker_retry_count_ret) {
799 // Make sure you read the note in attempt_allocation_humongous().
800
801 assert_heap_not_locked_and_not_at_safepoint();
802 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
803 "be called for humongous allocation requests");
804
805 // We should only get here after the first-level allocation attempt
806 // (attempt_allocation()) failed to allocate.
807
808 // We will loop until a) we manage to successfully perform the
809 // allocation or b) we successfully schedule a collection which
810 // fails to perform the allocation. b) is the only case when we'll
811 // return NULL.
812 HeapWord* result = NULL;
813 for (int try_count = 1; /* we'll return */; try_count += 1) {
814 bool should_try_gc;
815 uint gc_count_before;
816
817 {
818 MutexLockerEx x(Heap_lock);
819 result = _allocator->attempt_allocation_locked(word_size, context);
820 if (result != NULL) {
821 return result;
822 }
823
824 if (GC_locker::is_active_and_needs_gc()) {
825 if (g1_policy()->can_expand_young_list()) {
826 // No need for an ergo verbose message here,
827 // can_expand_young_list() does this when it returns true.
828 result = _allocator->attempt_allocation_force(word_size, context);
829 if (result != NULL) {
830 return result;
831 }
832 }
833 should_try_gc = false;
834 } else {
835 // The GCLocker may not be active but the GCLocker initiated
836 // GC may not yet have been performed (GCLocker::needs_gc()
837 // returns true). In this case we do not try this GC and
838 // wait until the GCLocker initiated GC is performed, and
839 // then retry the allocation.
840 if (GC_locker::needs_gc()) {
841 should_try_gc = false;
842 } else {
843 // Read the GC count while still holding the Heap_lock.
844 gc_count_before = total_collections();
845 should_try_gc = true;
846 }
847 }
848 }
849
850 if (should_try_gc) {
851 bool succeeded;
852 result = do_collection_pause(word_size, gc_count_before, &succeeded,
853 GCCause::_g1_inc_collection_pause);
854 if (result != NULL) {
855 assert(succeeded, "only way to get back a non-NULL result");
856 return result;
857 }
858
859 if (succeeded) {
860 // If we get here we successfully scheduled a collection which
861 // failed to allocate. No point in trying to allocate
862 // further. We'll just return NULL.
863 MutexLockerEx x(Heap_lock);
864 *gc_count_before_ret = total_collections();
865 return NULL;
866 }
867 } else {
868 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
869 MutexLockerEx x(Heap_lock);
870 *gc_count_before_ret = total_collections();
871 return NULL;
872 }
873 // The GCLocker is either active or the GCLocker initiated
874 // GC has not yet been performed. Stall until it is and
875 // then retry the allocation.
876 GC_locker::stall_until_clear();
877 (*gclocker_retry_count_ret) += 1;
878 }
879
880 // We can reach here if we were unsuccessful in scheduling a
881 // collection (because another thread beat us to it) or if we were
882 // stalled due to the GC locker. In either can we should retry the
883 // allocation attempt in case another thread successfully
884 // performed a collection and reclaimed enough space. We do the
885 // first attempt (without holding the Heap_lock) here and the
886 // follow-on attempt will be at the start of the next loop
887 // iteration (after taking the Heap_lock).
888 result = _allocator->attempt_allocation(word_size, context);
889 if (result != NULL) {
890 return result;
891 }
892
893 // Give a warning if we seem to be looping forever.
894 if ((QueuedAllocationWarningCount > 0) &&
895 (try_count % QueuedAllocationWarningCount == 0)) {
896 warning("G1CollectedHeap::attempt_allocation_slow() "
897 "retries %d times", try_count);
898 }
899 }
900
901 ShouldNotReachHere();
902 return NULL;
903 }
904
905 void G1CollectedHeap::begin_archive_alloc_range() {
906 assert_at_safepoint(true /* should_be_vm_thread */);
907 if (_archive_allocator == NULL) {
908 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
909 }
910 }
911
912 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
913 // Allocations in archive regions cannot be of a size that would be considered
914 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
915 // may be different at archive-restore time.
916 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
917 }
918
919 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
920 assert_at_safepoint(true /* should_be_vm_thread */);
921 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
922 if (is_archive_alloc_too_large(word_size)) {
923 return NULL;
924 }
925 return _archive_allocator->archive_mem_allocate(word_size);
926 }
927
928 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
929 size_t end_alignment_in_bytes) {
930 assert_at_safepoint(true /* should_be_vm_thread */);
931 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
932
933 // Call complete_archive to do the real work, filling in the MemRegion
934 // array with the archive regions.
935 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
936 delete _archive_allocator;
937 _archive_allocator = NULL;
938 }
939
940 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
941 assert(ranges != NULL, "MemRegion array NULL");
942 assert(count != 0, "No MemRegions provided");
943 MemRegion reserved = _hrm.reserved();
944 for (size_t i = 0; i < count; i++) {
945 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
946 return false;
947 }
948 }
949 return true;
950 }
951
952 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
953 assert(!is_init_completed(), "Expect to be called at JVM init time");
954 assert(ranges != NULL, "MemRegion array NULL");
955 assert(count != 0, "No MemRegions provided");
956 MutexLockerEx x(Heap_lock);
957
958 MemRegion reserved = _hrm.reserved();
959 HeapWord* prev_last_addr = NULL;
960 HeapRegion* prev_last_region = NULL;
961
962 // Temporarily disable pretouching of heap pages. This interface is used
963 // when mmap'ing archived heap data in, so pre-touching is wasted.
964 FlagSetting fs(AlwaysPreTouch, false);
965
966 // Enable archive object checking in G1MarkSweep. We have to let it know
967 // about each archive range, so that objects in those ranges aren't marked.
968 G1MarkSweep::enable_archive_object_check();
969
970 // For each specified MemRegion range, allocate the corresponding G1
971 // regions and mark them as archive regions. We expect the ranges in
972 // ascending starting address order, without overlap.
973 for (size_t i = 0; i < count; i++) {
974 MemRegion curr_range = ranges[i];
975 HeapWord* start_address = curr_range.start();
976 size_t word_size = curr_range.word_size();
977 HeapWord* last_address = curr_range.last();
978 size_t commits = 0;
979
980 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
981 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
982 p2i(start_address), p2i(last_address)));
983 guarantee(start_address > prev_last_addr,
984 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
985 p2i(start_address), p2i(prev_last_addr)));
986 prev_last_addr = last_address;
987
988 // Check for ranges that start in the same G1 region in which the previous
989 // range ended, and adjust the start address so we don't try to allocate
990 // the same region again. If the current range is entirely within that
991 // region, skip it, just adjusting the recorded top.
992 HeapRegion* start_region = _hrm.addr_to_region(start_address);
993 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
994 start_address = start_region->end();
995 if (start_address > last_address) {
996 increase_used(word_size * HeapWordSize);
997 start_region->set_top(last_address + 1);
998 continue;
999 }
1000 start_region->set_top(start_address);
1001 curr_range = MemRegion(start_address, last_address + 1);
1002 start_region = _hrm.addr_to_region(start_address);
1003 }
1004
1005 // Perform the actual region allocation, exiting if it fails.
1006 // Then note how much new space we have allocated.
1007 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1008 return false;
1009 }
1010 increase_used(word_size * HeapWordSize);
1011 if (commits != 0) {
1012 ergo_verbose1(ErgoHeapSizing,
1013 "attempt heap expansion",
1014 ergo_format_reason("allocate archive regions")
1015 ergo_format_byte("total size"),
1016 HeapRegion::GrainWords * HeapWordSize * commits);
1017 }
1018
1019 // Mark each G1 region touched by the range as archive, add it to the old set,
1020 // and set the allocation context and top.
1021 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1022 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1023 prev_last_region = last_region;
1024
1025 while (curr_region != NULL) {
1026 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1027 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1028 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1029 curr_region->set_allocation_context(AllocationContext::system());
1030 curr_region->set_archive();
1031 _old_set.add(curr_region);
1032 if (curr_region != last_region) {
1033 curr_region->set_top(curr_region->end());
1034 curr_region = _hrm.next_region_in_heap(curr_region);
1035 } else {
1036 curr_region->set_top(last_address + 1);
1037 curr_region = NULL;
1038 }
1039 }
1040
1041 // Notify mark-sweep of the archive range.
1042 G1MarkSweep::set_range_archive(curr_range, true);
1043 }
1044 return true;
1045 }
1046
1047 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1048 assert(!is_init_completed(), "Expect to be called at JVM init time");
1049 assert(ranges != NULL, "MemRegion array NULL");
1050 assert(count != 0, "No MemRegions provided");
1051 MemRegion reserved = _hrm.reserved();
1052 HeapWord *prev_last_addr = NULL;
1053 HeapRegion* prev_last_region = NULL;
1054
1055 // For each MemRegion, create filler objects, if needed, in the G1 regions
1056 // that contain the address range. The address range actually within the
1057 // MemRegion will not be modified. That is assumed to have been initialized
1058 // elsewhere, probably via an mmap of archived heap data.
1059 MutexLockerEx x(Heap_lock);
1060 for (size_t i = 0; i < count; i++) {
1061 HeapWord* start_address = ranges[i].start();
1062 HeapWord* last_address = ranges[i].last();
1063
1064 assert(reserved.contains(start_address) && reserved.contains(last_address),
1065 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1066 p2i(start_address), p2i(last_address)));
1067 assert(start_address > prev_last_addr,
1068 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1069 p2i(start_address), p2i(prev_last_addr)));
1070
1071 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1072 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1073 HeapWord* bottom_address = start_region->bottom();
1074
1075 // Check for a range beginning in the same region in which the
1076 // previous one ended.
1077 if (start_region == prev_last_region) {
1078 bottom_address = prev_last_addr + 1;
1079 }
1080
1081 // Verify that the regions were all marked as archive regions by
1082 // alloc_archive_regions.
1083 HeapRegion* curr_region = start_region;
1084 while (curr_region != NULL) {
1085 guarantee(curr_region->is_archive(),
1086 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1087 if (curr_region != last_region) {
1088 curr_region = _hrm.next_region_in_heap(curr_region);
1089 } else {
1090 curr_region = NULL;
1091 }
1092 }
1093
1094 prev_last_addr = last_address;
1095 prev_last_region = last_region;
1096
1097 // Fill the memory below the allocated range with dummy object(s),
1098 // if the region bottom does not match the range start, or if the previous
1099 // range ended within the same G1 region, and there is a gap.
1100 if (start_address != bottom_address) {
1101 size_t fill_size = pointer_delta(start_address, bottom_address);
1102 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1103 increase_used(fill_size * HeapWordSize);
1104 }
1105 }
1106 }
1107
1108 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1109 uint* gc_count_before_ret,
1110 uint* gclocker_retry_count_ret) {
1111 assert_heap_not_locked_and_not_at_safepoint();
1112 assert(!is_humongous(word_size), "attempt_allocation() should not "
1113 "be called for humongous allocation requests");
1114
1115 AllocationContext_t context = AllocationContext::current();
1116 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1117
1118 if (result == NULL) {
1119 result = attempt_allocation_slow(word_size,
1120 context,
1121 gc_count_before_ret,
1122 gclocker_retry_count_ret);
1123 }
1124 assert_heap_not_locked();
1125 if (result != NULL) {
1126 dirty_young_block(result, word_size);
1127 }
1128 return result;
1129 }
1130
1131 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1132 assert(!is_init_completed(), "Expect to be called at JVM init time");
1133 assert(ranges != NULL, "MemRegion array NULL");
1134 assert(count != 0, "No MemRegions provided");
1135 MemRegion reserved = _hrm.reserved();
1136 HeapWord* prev_last_addr = NULL;
1137 HeapRegion* prev_last_region = NULL;
1138 size_t size_used = 0;
1139 size_t uncommitted_regions = 0;
1140
1141 // For each Memregion, free the G1 regions that constitute it, and
1142 // notify mark-sweep that the range is no longer to be considered 'archive.'
1143 MutexLockerEx x(Heap_lock);
1144 for (size_t i = 0; i < count; i++) {
1145 HeapWord* start_address = ranges[i].start();
1146 HeapWord* last_address = ranges[i].last();
1147
1148 assert(reserved.contains(start_address) && reserved.contains(last_address),
1149 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1150 p2i(start_address), p2i(last_address)));
1151 assert(start_address > prev_last_addr,
1152 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1153 p2i(start_address), p2i(prev_last_addr)));
1154 size_used += ranges[i].byte_size();
1155 prev_last_addr = last_address;
1156
1157 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1158 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1159
1160 // Check for ranges that start in the same G1 region in which the previous
1161 // range ended, and adjust the start address so we don't try to free
1162 // the same region again. If the current range is entirely within that
1163 // region, skip it.
1164 if (start_region == prev_last_region) {
1165 start_address = start_region->end();
1166 if (start_address > last_address) {
1167 continue;
1168 }
1169 start_region = _hrm.addr_to_region(start_address);
1170 }
1171 prev_last_region = last_region;
1172
1173 // After verifying that each region was marked as an archive region by
1174 // alloc_archive_regions, set it free and empty and uncommit it.
1175 HeapRegion* curr_region = start_region;
1176 while (curr_region != NULL) {
1177 guarantee(curr_region->is_archive(),
1178 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1179 uint curr_index = curr_region->hrm_index();
1180 _old_set.remove(curr_region);
1181 curr_region->set_free();
1182 curr_region->set_top(curr_region->bottom());
1183 if (curr_region != last_region) {
1184 curr_region = _hrm.next_region_in_heap(curr_region);
1185 } else {
1186 curr_region = NULL;
1187 }
1188 _hrm.shrink_at(curr_index, 1);
1189 uncommitted_regions++;
1190 }
1191
1192 // Notify mark-sweep that this is no longer an archive range.
1193 G1MarkSweep::set_range_archive(ranges[i], false);
1194 }
1195
1196 if (uncommitted_regions != 0) {
1197 ergo_verbose1(ErgoHeapSizing,
1198 "attempt heap shrinking",
1199 ergo_format_reason("uncommitted archive regions")
1200 ergo_format_byte("total size"),
1201 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1202 }
1203 decrease_used(size_used);
1204 }
1205
1206 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1207 uint* gc_count_before_ret,
1208 uint* gclocker_retry_count_ret) {
1209 // The structure of this method has a lot of similarities to
1210 // attempt_allocation_slow(). The reason these two were not merged
1211 // into a single one is that such a method would require several "if
1212 // allocation is not humongous do this, otherwise do that"
1213 // conditional paths which would obscure its flow. In fact, an early
1214 // version of this code did use a unified method which was harder to
1215 // follow and, as a result, it had subtle bugs that were hard to
1216 // track down. So keeping these two methods separate allows each to
1217 // be more readable. It will be good to keep these two in sync as
1218 // much as possible.
1219
1220 assert_heap_not_locked_and_not_at_safepoint();
1221 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1222 "should only be called for humongous allocations");
1223
1224 // Humongous objects can exhaust the heap quickly, so we should check if we
1225 // need to start a marking cycle at each humongous object allocation. We do
1226 // the check before we do the actual allocation. The reason for doing it
1227 // before the allocation is that we avoid having to keep track of the newly
1228 // allocated memory while we do a GC.
1229 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1230 word_size)) {
1231 collect(GCCause::_g1_humongous_allocation);
1232 }
1233
1234 // We will loop until a) we manage to successfully perform the
1235 // allocation or b) we successfully schedule a collection which
1236 // fails to perform the allocation. b) is the only case when we'll
1237 // return NULL.
1238 HeapWord* result = NULL;
1239 for (int try_count = 1; /* we'll return */; try_count += 1) {
1240 bool should_try_gc;
1241 uint gc_count_before;
1242
1243 {
1244 MutexLockerEx x(Heap_lock);
1245
1246 // Given that humongous objects are not allocated in young
1247 // regions, we'll first try to do the allocation without doing a
1248 // collection hoping that there's enough space in the heap.
1249 result = humongous_obj_allocate(word_size, AllocationContext::current());
1250 if (result != NULL) {
1251 return result;
1252 }
1253
1254 if (GC_locker::is_active_and_needs_gc()) {
1255 should_try_gc = false;
1256 } else {
1257 // The GCLocker may not be active but the GCLocker initiated
1258 // GC may not yet have been performed (GCLocker::needs_gc()
1259 // returns true). In this case we do not try this GC and
1260 // wait until the GCLocker initiated GC is performed, and
1261 // then retry the allocation.
1262 if (GC_locker::needs_gc()) {
1263 should_try_gc = false;
1264 } else {
1265 // Read the GC count while still holding the Heap_lock.
1266 gc_count_before = total_collections();
1267 should_try_gc = true;
1268 }
1269 }
1270 }
1271
1272 if (should_try_gc) {
1273 // If we failed to allocate the humongous object, we should try to
1274 // do a collection pause (if we're allowed) in case it reclaims
1275 // enough space for the allocation to succeed after the pause.
1276
1277 bool succeeded;
1278 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1279 GCCause::_g1_humongous_allocation);
1280 if (result != NULL) {
1281 assert(succeeded, "only way to get back a non-NULL result");
1282 return result;
1283 }
1284
1285 if (succeeded) {
1286 // If we get here we successfully scheduled a collection which
1287 // failed to allocate. No point in trying to allocate
1288 // further. We'll just return NULL.
1289 MutexLockerEx x(Heap_lock);
1290 *gc_count_before_ret = total_collections();
1291 return NULL;
1292 }
1293 } else {
1294 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1295 MutexLockerEx x(Heap_lock);
1296 *gc_count_before_ret = total_collections();
1297 return NULL;
1298 }
1299 // The GCLocker is either active or the GCLocker initiated
1300 // GC has not yet been performed. Stall until it is and
1301 // then retry the allocation.
1302 GC_locker::stall_until_clear();
1303 (*gclocker_retry_count_ret) += 1;
1304 }
1305
1306 // We can reach here if we were unsuccessful in scheduling a
1307 // collection (because another thread beat us to it) or if we were
1308 // stalled due to the GC locker. In either can we should retry the
1309 // allocation attempt in case another thread successfully
1310 // performed a collection and reclaimed enough space. Give a
1311 // warning if we seem to be looping forever.
1312
1313 if ((QueuedAllocationWarningCount > 0) &&
1314 (try_count % QueuedAllocationWarningCount == 0)) {
1315 warning("G1CollectedHeap::attempt_allocation_humongous() "
1316 "retries %d times", try_count);
1317 }
1318 }
1319
1320 ShouldNotReachHere();
1321 return NULL;
1322 }
1323
1324 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1325 AllocationContext_t context,
1326 bool expect_null_mutator_alloc_region) {
1327 assert_at_safepoint(true /* should_be_vm_thread */);
1328 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1329 "the current alloc region was unexpectedly found to be non-NULL");
1330
1331 if (!is_humongous(word_size)) {
1332 return _allocator->attempt_allocation_locked(word_size, context);
1333 } else {
1334 HeapWord* result = humongous_obj_allocate(word_size, context);
1335 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1336 collector_state()->set_initiate_conc_mark_if_possible(true);
1337 }
1338 return result;
1339 }
1340
1341 ShouldNotReachHere();
1342 }
1343
1344 class PostMCRemSetClearClosure: public HeapRegionClosure {
1345 G1CollectedHeap* _g1h;
1346 ModRefBarrierSet* _mr_bs;
1347 public:
1348 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1349 _g1h(g1h), _mr_bs(mr_bs) {}
1350
1351 bool doHeapRegion(HeapRegion* r) {
1352 HeapRegionRemSet* hrrs = r->rem_set();
1353
1354 if (r->is_continues_humongous()) {
1355 // We'll assert that the strong code root list and RSet is empty
1356 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1357 assert(hrrs->occupied() == 0, "RSet should be empty");
1358 return false;
1359 }
1360
1361 _g1h->reset_gc_time_stamps(r);
1362 hrrs->clear();
1363 // You might think here that we could clear just the cards
1364 // corresponding to the used region. But no: if we leave a dirty card
1365 // in a region we might allocate into, then it would prevent that card
1366 // from being enqueued, and cause it to be missed.
1367 // Re: the performance cost: we shouldn't be doing full GC anyway!
1368 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1369
1370 return false;
1371 }
1372 };
1373
1374 void G1CollectedHeap::clear_rsets_post_compaction() {
1375 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1376 heap_region_iterate(&rs_clear);
1377 }
1378
1379 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1380 G1CollectedHeap* _g1h;
1381 UpdateRSOopClosure _cl;
1382 public:
1383 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1384 _cl(g1->g1_rem_set(), worker_i),
1385 _g1h(g1)
1386 { }
1387
1388 bool doHeapRegion(HeapRegion* r) {
1389 if (!r->is_continues_humongous()) {
1390 _cl.set_from(r);
1391 r->oop_iterate(&_cl);
1392 }
1393 return false;
1394 }
1395 };
1396
1397 class ParRebuildRSTask: public AbstractGangTask {
1398 G1CollectedHeap* _g1;
1399 HeapRegionClaimer _hrclaimer;
1400
1401 public:
1402 ParRebuildRSTask(G1CollectedHeap* g1) :
1403 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1404
1405 void work(uint worker_id) {
1406 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1407 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1408 }
1409 };
1410
1411 class PostCompactionPrinterClosure: public HeapRegionClosure {
1412 private:
1413 G1HRPrinter* _hr_printer;
1414 public:
1415 bool doHeapRegion(HeapRegion* hr) {
1416 assert(!hr->is_young(), "not expecting to find young regions");
1417 if (hr->is_free()) {
1418 // We only generate output for non-empty regions.
1419 } else if (hr->is_starts_humongous()) {
1420 if (hr->region_num() == 1) {
1421 // single humongous region
1422 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1423 } else {
1424 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1425 }
1426 } else if (hr->is_continues_humongous()) {
1427 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1428 } else if (hr->is_archive()) {
1429 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1430 } else if (hr->is_old()) {
1431 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1432 } else {
1433 ShouldNotReachHere();
1434 }
1435 return false;
1436 }
1437
1438 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1439 : _hr_printer(hr_printer) { }
1440 };
1441
1442 void G1CollectedHeap::print_hrm_post_compaction() {
1443 PostCompactionPrinterClosure cl(hr_printer());
1444 heap_region_iterate(&cl);
1445 }
1446
1447 bool G1CollectedHeap::do_collection(bool explicit_gc,
1448 bool clear_all_soft_refs,
1449 size_t word_size) {
1450 assert_at_safepoint(true /* should_be_vm_thread */);
1451
1452 if (GC_locker::check_active_before_gc()) {
1453 return false;
1454 }
1455
1456 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1457 gc_timer->register_gc_start();
1458
1459 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1460 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1461
1462 SvcGCMarker sgcm(SvcGCMarker::FULL);
1463 ResourceMark rm;
1464
1465 G1Log::update_level();
1466 print_heap_before_gc();
1467 trace_heap_before_gc(gc_tracer);
1468
1469 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1470
1471 verify_region_sets_optional();
1472
1473 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1474 collector_policy()->should_clear_all_soft_refs();
1475
1476 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1477
1478 {
1479 IsGCActiveMark x;
1480
1481 // Timing
1482 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1483 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1484
1485 {
1486 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1487 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1488 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1489
1490 g1_policy()->record_full_collection_start();
1491
1492 // Note: When we have a more flexible GC logging framework that
1493 // allows us to add optional attributes to a GC log record we
1494 // could consider timing and reporting how long we wait in the
1495 // following two methods.
1496 wait_while_free_regions_coming();
1497 // If we start the compaction before the CM threads finish
1498 // scanning the root regions we might trip them over as we'll
1499 // be moving objects / updating references. So let's wait until
1500 // they are done. By telling them to abort, they should complete
1501 // early.
1502 _cm->root_regions()->abort();
1503 _cm->root_regions()->wait_until_scan_finished();
1504 append_secondary_free_list_if_not_empty_with_lock();
1505
1506 gc_prologue(true);
1507 increment_total_collections(true /* full gc */);
1508 increment_old_marking_cycles_started();
1509
1510 assert(used() == recalculate_used(), "Should be equal");
1511
1512 verify_before_gc();
1513
1514 check_bitmaps("Full GC Start");
1515 pre_full_gc_dump(gc_timer);
1516
1517 COMPILER2_PRESENT(DerivedPointerTable::clear());
1518
1519 // Disable discovery and empty the discovered lists
1520 // for the CM ref processor.
1521 ref_processor_cm()->disable_discovery();
1522 ref_processor_cm()->abandon_partial_discovery();
1523 ref_processor_cm()->verify_no_references_recorded();
1524
1525 // Abandon current iterations of concurrent marking and concurrent
1526 // refinement, if any are in progress. We have to do this before
1527 // wait_until_scan_finished() below.
1528 concurrent_mark()->abort();
1529
1530 // Make sure we'll choose a new allocation region afterwards.
1531 _allocator->release_mutator_alloc_region();
1532 _allocator->abandon_gc_alloc_regions();
1533 g1_rem_set()->cleanupHRRS();
1534
1535 // We should call this after we retire any currently active alloc
1536 // regions so that all the ALLOC / RETIRE events are generated
1537 // before the start GC event.
1538 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1539
1540 // We may have added regions to the current incremental collection
1541 // set between the last GC or pause and now. We need to clear the
1542 // incremental collection set and then start rebuilding it afresh
1543 // after this full GC.
1544 abandon_collection_set(g1_policy()->inc_cset_head());
1545 g1_policy()->clear_incremental_cset();
1546 g1_policy()->stop_incremental_cset_building();
1547
1548 tear_down_region_sets(false /* free_list_only */);
1549 collector_state()->set_gcs_are_young(true);
1550
1551 // See the comments in g1CollectedHeap.hpp and
1552 // G1CollectedHeap::ref_processing_init() about
1553 // how reference processing currently works in G1.
1554
1555 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1556 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1557
1558 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1559 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1560
1561 ref_processor_stw()->enable_discovery();
1562 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1563
1564 // Do collection work
1565 {
1566 HandleMark hm; // Discard invalid handles created during gc
1567 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1568 }
1569
1570 assert(num_free_regions() == 0, "we should not have added any free regions");
1571 rebuild_region_sets(false /* free_list_only */);
1572
1573 // Enqueue any discovered reference objects that have
1574 // not been removed from the discovered lists.
1575 ref_processor_stw()->enqueue_discovered_references();
1576
1577 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1578
1579 MemoryService::track_memory_usage();
1580
1581 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1582 ref_processor_stw()->verify_no_references_recorded();
1583
1584 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1585 ClassLoaderDataGraph::purge();
1586 MetaspaceAux::verify_metrics();
1587
1588 // Note: since we've just done a full GC, concurrent
1589 // marking is no longer active. Therefore we need not
1590 // re-enable reference discovery for the CM ref processor.
1591 // That will be done at the start of the next marking cycle.
1592 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1593 ref_processor_cm()->verify_no_references_recorded();
1594
1595 reset_gc_time_stamp();
1596 // Since everything potentially moved, we will clear all remembered
1597 // sets, and clear all cards. Later we will rebuild remembered
1598 // sets. We will also reset the GC time stamps of the regions.
1599 clear_rsets_post_compaction();
1600 check_gc_time_stamps();
1601
1602 // Resize the heap if necessary.
1603 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1604
1605 if (_hr_printer.is_active()) {
1606 // We should do this after we potentially resize the heap so
1607 // that all the COMMIT / UNCOMMIT events are generated before
1608 // the end GC event.
1609
1610 print_hrm_post_compaction();
1611 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1612 }
1613
1614 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1615 if (hot_card_cache->use_cache()) {
1616 hot_card_cache->reset_card_counts();
1617 hot_card_cache->reset_hot_cache();
1618 }
1619
1620 // Rebuild remembered sets of all regions.
1621 uint n_workers =
1622 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1623 workers()->active_workers(),
1624 Threads::number_of_non_daemon_threads());
1625 workers()->set_active_workers(n_workers);
1626
1627 ParRebuildRSTask rebuild_rs_task(this);
1628 workers()->run_task(&rebuild_rs_task);
1629
1630 // Rebuild the strong code root lists for each region
1631 rebuild_strong_code_roots();
1632
1633 if (true) { // FIXME
1634 MetaspaceGC::compute_new_size();
1635 }
1636
1637 #ifdef TRACESPINNING
1638 ParallelTaskTerminator::print_termination_counts();
1639 #endif
1640
1641 // Discard all rset updates
1642 JavaThread::dirty_card_queue_set().abandon_logs();
1643 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1644
1645 _young_list->reset_sampled_info();
1646 // At this point there should be no regions in the
1647 // entire heap tagged as young.
1648 assert(check_young_list_empty(true /* check_heap */),
1649 "young list should be empty at this point");
1650
1651 // Update the number of full collections that have been completed.
1652 increment_old_marking_cycles_completed(false /* concurrent */);
1653
1654 _hrm.verify_optional();
1655 verify_region_sets_optional();
1656
1657 verify_after_gc();
1658
1659 // Clear the previous marking bitmap, if needed for bitmap verification.
1660 // Note we cannot do this when we clear the next marking bitmap in
1661 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1662 // objects marked during a full GC against the previous bitmap.
1663 // But we need to clear it before calling check_bitmaps below since
1664 // the full GC has compacted objects and updated TAMS but not updated
1665 // the prev bitmap.
1666 if (G1VerifyBitmaps) {
1667 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1668 }
1669 check_bitmaps("Full GC End");
1670
1671 // Start a new incremental collection set for the next pause
1672 assert(g1_policy()->collection_set() == NULL, "must be");
1673 g1_policy()->start_incremental_cset_building();
1674
1675 clear_cset_fast_test();
1676
1677 _allocator->init_mutator_alloc_region();
1678
1679 g1_policy()->record_full_collection_end();
1680
1681 if (G1Log::fine()) {
1682 g1_policy()->print_heap_transition();
1683 }
1684
1685 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1686 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1687 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1688 // before any GC notifications are raised.
1689 g1mm()->update_sizes();
1690
1691 gc_epilogue(true);
1692 }
1693
1694 if (G1Log::finer()) {
1695 g1_policy()->print_detailed_heap_transition(true /* full */);
1696 }
1697
1698 print_heap_after_gc();
1699 trace_heap_after_gc(gc_tracer);
1700
1701 post_full_gc_dump(gc_timer);
1702
1703 gc_timer->register_gc_end();
1704 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1705 }
1706
1707 return true;
1708 }
1709
1710 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1711 // do_collection() will return whether it succeeded in performing
1712 // the GC. Currently, there is no facility on the
1713 // do_full_collection() API to notify the caller than the collection
1714 // did not succeed (e.g., because it was locked out by the GC
1715 // locker). So, right now, we'll ignore the return value.
1716 bool dummy = do_collection(true, /* explicit_gc */
1717 clear_all_soft_refs,
1718 0 /* word_size */);
1719 }
1720
1721 // This code is mostly copied from TenuredGeneration.
1722 void
1723 G1CollectedHeap::
1724 resize_if_necessary_after_full_collection(size_t word_size) {
1725 // Include the current allocation, if any, and bytes that will be
1726 // pre-allocated to support collections, as "used".
1727 const size_t used_after_gc = used();
1728 const size_t capacity_after_gc = capacity();
1729 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1730
1731 // This is enforced in arguments.cpp.
1732 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1733 "otherwise the code below doesn't make sense");
1734
1735 // We don't have floating point command-line arguments
1736 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1737 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1738 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1739 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1740
1741 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1742 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1743
1744 // We have to be careful here as these two calculations can overflow
1745 // 32-bit size_t's.
1746 double used_after_gc_d = (double) used_after_gc;
1747 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1748 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1749
1750 // Let's make sure that they are both under the max heap size, which
1751 // by default will make them fit into a size_t.
1752 double desired_capacity_upper_bound = (double) max_heap_size;
1753 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1754 desired_capacity_upper_bound);
1755 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1756 desired_capacity_upper_bound);
1757
1758 // We can now safely turn them into size_t's.
1759 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1760 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1761
1762 // This assert only makes sense here, before we adjust them
1763 // with respect to the min and max heap size.
1764 assert(minimum_desired_capacity <= maximum_desired_capacity,
1765 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1766 "maximum_desired_capacity = " SIZE_FORMAT,
1767 minimum_desired_capacity, maximum_desired_capacity));
1768
1769 // Should not be greater than the heap max size. No need to adjust
1770 // it with respect to the heap min size as it's a lower bound (i.e.,
1771 // we'll try to make the capacity larger than it, not smaller).
1772 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1773 // Should not be less than the heap min size. No need to adjust it
1774 // with respect to the heap max size as it's an upper bound (i.e.,
1775 // we'll try to make the capacity smaller than it, not greater).
1776 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1777
1778 if (capacity_after_gc < minimum_desired_capacity) {
1779 // Don't expand unless it's significant
1780 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1781 ergo_verbose4(ErgoHeapSizing,
1782 "attempt heap expansion",
1783 ergo_format_reason("capacity lower than "
1784 "min desired capacity after Full GC")
1785 ergo_format_byte("capacity")
1786 ergo_format_byte("occupancy")
1787 ergo_format_byte_perc("min desired capacity"),
1788 capacity_after_gc, used_after_gc,
1789 minimum_desired_capacity, (double) MinHeapFreeRatio);
1790 expand(expand_bytes);
1791
1792 // No expansion, now see if we want to shrink
1793 } else if (capacity_after_gc > maximum_desired_capacity) {
1794 // Capacity too large, compute shrinking size
1795 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1796 ergo_verbose4(ErgoHeapSizing,
1797 "attempt heap shrinking",
1798 ergo_format_reason("capacity higher than "
1799 "max desired capacity after Full GC")
1800 ergo_format_byte("capacity")
1801 ergo_format_byte("occupancy")
1802 ergo_format_byte_perc("max desired capacity"),
1803 capacity_after_gc, used_after_gc,
1804 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1805 shrink(shrink_bytes);
1806 }
1807 }
1808
1809
1810 HeapWord*
1811 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1812 AllocationContext_t context,
1813 bool* succeeded) {
1814 assert_at_safepoint(true /* should_be_vm_thread */);
1815
1816 *succeeded = true;
1817 // Let's attempt the allocation first.
1818 HeapWord* result =
1819 attempt_allocation_at_safepoint(word_size,
1820 context,
1821 false /* expect_null_mutator_alloc_region */);
1822 if (result != NULL) {
1823 assert(*succeeded, "sanity");
1824 return result;
1825 }
1826
1827 // In a G1 heap, we're supposed to keep allocation from failing by
1828 // incremental pauses. Therefore, at least for now, we'll favor
1829 // expansion over collection. (This might change in the future if we can
1830 // do something smarter than full collection to satisfy a failed alloc.)
1831 result = expand_and_allocate(word_size, context);
1832 if (result != NULL) {
1833 assert(*succeeded, "sanity");
1834 return result;
1835 }
1836
1837 // Expansion didn't work, we'll try to do a Full GC.
1838 bool gc_succeeded = do_collection(false, /* explicit_gc */
1839 false, /* clear_all_soft_refs */
1840 word_size);
1841 if (!gc_succeeded) {
1842 *succeeded = false;
1843 return NULL;
1844 }
1845
1846 // Retry the allocation
1847 result = attempt_allocation_at_safepoint(word_size,
1848 context,
1849 true /* expect_null_mutator_alloc_region */);
1850 if (result != NULL) {
1851 assert(*succeeded, "sanity");
1852 return result;
1853 }
1854
1855 // Then, try a Full GC that will collect all soft references.
1856 gc_succeeded = do_collection(false, /* explicit_gc */
1857 true, /* clear_all_soft_refs */
1858 word_size);
1859 if (!gc_succeeded) {
1860 *succeeded = false;
1861 return NULL;
1862 }
1863
1864 // Retry the allocation once more
1865 result = attempt_allocation_at_safepoint(word_size,
1866 context,
1867 true /* expect_null_mutator_alloc_region */);
1868 if (result != NULL) {
1869 assert(*succeeded, "sanity");
1870 return result;
1871 }
1872
1873 assert(!collector_policy()->should_clear_all_soft_refs(),
1874 "Flag should have been handled and cleared prior to this point");
1875
1876 // What else? We might try synchronous finalization later. If the total
1877 // space available is large enough for the allocation, then a more
1878 // complete compaction phase than we've tried so far might be
1879 // appropriate.
1880 assert(*succeeded, "sanity");
1881 return NULL;
1882 }
1883
1884 // Attempting to expand the heap sufficiently
1885 // to support an allocation of the given "word_size". If
1886 // successful, perform the allocation and return the address of the
1887 // allocated block, or else "NULL".
1888
1889 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1890 assert_at_safepoint(true /* should_be_vm_thread */);
1891
1892 verify_region_sets_optional();
1893
1894 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1895 ergo_verbose1(ErgoHeapSizing,
1896 "attempt heap expansion",
1897 ergo_format_reason("allocation request failed")
1898 ergo_format_byte("allocation request"),
1899 word_size * HeapWordSize);
1900 if (expand(expand_bytes)) {
1901 _hrm.verify_optional();
1902 verify_region_sets_optional();
1903 return attempt_allocation_at_safepoint(word_size,
1904 context,
1905 false /* expect_null_mutator_alloc_region */);
1906 }
1907 return NULL;
1908 }
1909
1910 bool G1CollectedHeap::expand(size_t expand_bytes) {
1911 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1912 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1913 HeapRegion::GrainBytes);
1914 ergo_verbose2(ErgoHeapSizing,
1915 "expand the heap",
1916 ergo_format_byte("requested expansion amount")
1917 ergo_format_byte("attempted expansion amount"),
1918 expand_bytes, aligned_expand_bytes);
1919
1920 if (is_maximal_no_gc()) {
1921 ergo_verbose0(ErgoHeapSizing,
1922 "did not expand the heap",
1923 ergo_format_reason("heap already fully expanded"));
1924 return false;
1925 }
1926
1927 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1928 assert(regions_to_expand > 0, "Must expand by at least one region");
1929
1930 uint expanded_by = _hrm.expand_by(regions_to_expand);
1931
1932 if (expanded_by > 0) {
1933 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1934 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1935 g1_policy()->record_new_heap_size(num_regions());
1936 } else {
1937 ergo_verbose0(ErgoHeapSizing,
1938 "did not expand the heap",
1939 ergo_format_reason("heap expansion operation failed"));
1940 // The expansion of the virtual storage space was unsuccessful.
1941 // Let's see if it was because we ran out of swap.
1942 if (G1ExitOnExpansionFailure &&
1943 _hrm.available() >= regions_to_expand) {
1944 // We had head room...
1945 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1946 }
1947 }
1948 return regions_to_expand > 0;
1949 }
1950
1951 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1952 size_t aligned_shrink_bytes =
1953 ReservedSpace::page_align_size_down(shrink_bytes);
1954 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1955 HeapRegion::GrainBytes);
1956 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1957
1958 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1959 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1960
1961 ergo_verbose3(ErgoHeapSizing,
1962 "shrink the heap",
1963 ergo_format_byte("requested shrinking amount")
1964 ergo_format_byte("aligned shrinking amount")
1965 ergo_format_byte("attempted shrinking amount"),
1966 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1967 if (num_regions_removed > 0) {
1968 g1_policy()->record_new_heap_size(num_regions());
1969 } else {
1970 ergo_verbose0(ErgoHeapSizing,
1971 "did not shrink the heap",
1972 ergo_format_reason("heap shrinking operation failed"));
1973 }
1974 }
1975
1976 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1977 verify_region_sets_optional();
1978
1979 // We should only reach here at the end of a Full GC which means we
1980 // should not not be holding to any GC alloc regions. The method
1981 // below will make sure of that and do any remaining clean up.
1982 _allocator->abandon_gc_alloc_regions();
1983
1984 // Instead of tearing down / rebuilding the free lists here, we
1985 // could instead use the remove_all_pending() method on free_list to
1986 // remove only the ones that we need to remove.
1987 tear_down_region_sets(true /* free_list_only */);
1988 shrink_helper(shrink_bytes);
1989 rebuild_region_sets(true /* free_list_only */);
1990
1991 _hrm.verify_optional();
1992 verify_region_sets_optional();
1993 }
1994
1995 // Public methods.
1996
1997 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1998 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1999 #endif // _MSC_VER
2000
2001
2002 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2003 CollectedHeap(),
2004 _g1_policy(policy_),
2005 _dirty_card_queue_set(false),
2006 _into_cset_dirty_card_queue_set(false),
2007 _is_alive_closure_cm(this),
2008 _is_alive_closure_stw(this),
2009 _ref_processor_cm(NULL),
2010 _ref_processor_stw(NULL),
2011 _bot_shared(NULL),
2012 _cg1r(NULL),
2013 _g1mm(NULL),
2014 _refine_cte_cl(NULL),
2015 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2016 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2017 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2018 _humongous_reclaim_candidates(),
2019 _has_humongous_reclaim_candidates(false),
2020 _archive_allocator(NULL),
2021 _free_regions_coming(false),
2022 _young_list(new YoungList(this)),
2023 _gc_time_stamp(0),
2024 _summary_bytes_used(0),
2025 _survivor_evac_stats(YoungPLABSize, PLABWeight),
2026 _old_evac_stats(OldPLABSize, PLABWeight),
2027 _expand_heap_after_alloc_failure(true),
2028 _surviving_young_words(NULL),
2029 _old_marking_cycles_started(0),
2030 _old_marking_cycles_completed(0),
2031 _heap_summary_sent(false),
2032 _in_cset_fast_test(),
2033 _dirty_cards_region_list(NULL),
2034 _worker_cset_start_region(NULL),
2035 _worker_cset_start_region_time_stamp(NULL),
2036 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2037 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2038 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2039 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2040
2041 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2042 /* are_GC_task_threads */true,
2043 /* are_ConcurrentGC_threads */false);
2044 _workers->initialize_workers();
2045
2046 _allocator = G1Allocator::create_allocator(this);
2047 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2048
2049 // Override the default _filler_array_max_size so that no humongous filler
2050 // objects are created.
2051 _filler_array_max_size = _humongous_object_threshold_in_words;
2052
2053 uint n_queues = ParallelGCThreads;
2054 _task_queues = new RefToScanQueueSet(n_queues);
2055
2056 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2057 assert(n_rem_sets > 0, "Invariant.");
2058
2059 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2060 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2061 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2062
2063 for (uint i = 0; i < n_queues; i++) {
2064 RefToScanQueue* q = new RefToScanQueue();
2065 q->initialize();
2066 _task_queues->register_queue(i, q);
2067 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2068 }
2069 clear_cset_start_regions();
2070
2071 // Initialize the G1EvacuationFailureALot counters and flags.
2072 NOT_PRODUCT(reset_evacuation_should_fail();)
2073
2074 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2075 }
2076
2077 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2078 size_t size,
2079 size_t translation_factor) {
2080 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2081 // Allocate a new reserved space, preferring to use large pages.
2082 ReservedSpace rs(size, preferred_page_size);
2083 G1RegionToSpaceMapper* result =
2084 G1RegionToSpaceMapper::create_mapper(rs,
2085 size,
2086 rs.alignment(),
2087 HeapRegion::GrainBytes,
2088 translation_factor,
2089 mtGC);
2090 if (TracePageSizes) {
2091 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2092 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2093 }
2094 return result;
2095 }
2096
2097 jint G1CollectedHeap::initialize() {
2098 CollectedHeap::pre_initialize();
2099 os::enable_vtime();
2100
2101 G1Log::init();
2102
2103 // Necessary to satisfy locking discipline assertions.
2104
2105 MutexLocker x(Heap_lock);
2106
2107 // We have to initialize the printer before committing the heap, as
2108 // it will be used then.
2109 _hr_printer.set_active(G1PrintHeapRegions);
2110
2111 // While there are no constraints in the GC code that HeapWordSize
2112 // be any particular value, there are multiple other areas in the
2113 // system which believe this to be true (e.g. oop->object_size in some
2114 // cases incorrectly returns the size in wordSize units rather than
2115 // HeapWordSize).
2116 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2117
2118 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2119 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2120 size_t heap_alignment = collector_policy()->heap_alignment();
2121
2122 // Ensure that the sizes are properly aligned.
2123 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2124 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2125 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2126
2127 _refine_cte_cl = new RefineCardTableEntryClosure();
2128
2129 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2130
2131 // Reserve the maximum.
2132
2133 // When compressed oops are enabled, the preferred heap base
2134 // is calculated by subtracting the requested size from the
2135 // 32Gb boundary and using the result as the base address for
2136 // heap reservation. If the requested size is not aligned to
2137 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2138 // into the ReservedHeapSpace constructor) then the actual
2139 // base of the reserved heap may end up differing from the
2140 // address that was requested (i.e. the preferred heap base).
2141 // If this happens then we could end up using a non-optimal
2142 // compressed oops mode.
2143
2144 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2145 heap_alignment);
2146
2147 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2148
2149 // Create the barrier set for the entire reserved region.
2150 G1SATBCardTableLoggingModRefBS* bs
2151 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2152 bs->initialize();
2153 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2154 set_barrier_set(bs);
2155
2156 // Also create a G1 rem set.
2157 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2158
2159 // Carve out the G1 part of the heap.
2160
2161 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2162 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2163 G1RegionToSpaceMapper* heap_storage =
2164 G1RegionToSpaceMapper::create_mapper(g1_rs,
2165 g1_rs.size(),
2166 page_size,
2167 HeapRegion::GrainBytes,
2168 1,
2169 mtJavaHeap);
2170 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2171 max_byte_size, page_size,
2172 heap_rs.base(),
2173 heap_rs.size());
2174 heap_storage->set_mapping_changed_listener(&_listener);
2175
2176 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2177 G1RegionToSpaceMapper* bot_storage =
2178 create_aux_memory_mapper("Block offset table",
2179 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2180 G1BlockOffsetSharedArray::heap_map_factor());
2181
2182 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2183 G1RegionToSpaceMapper* cardtable_storage =
2184 create_aux_memory_mapper("Card table",
2185 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2186 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2187
2188 G1RegionToSpaceMapper* card_counts_storage =
2189 create_aux_memory_mapper("Card counts table",
2190 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2191 G1CardCounts::heap_map_factor());
2192
2193 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2194 G1RegionToSpaceMapper* prev_bitmap_storage =
2195 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2196 G1RegionToSpaceMapper* next_bitmap_storage =
2197 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2198
2199 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2200 g1_barrier_set()->initialize(cardtable_storage);
2201 // Do later initialization work for concurrent refinement.
2202 _cg1r->init(card_counts_storage);
2203
2204 // 6843694 - ensure that the maximum region index can fit
2205 // in the remembered set structures.
2206 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2207 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2208
2209 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2210 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2211 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2212 "too many cards per region");
2213
2214 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2215
2216 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2217
2218 {
2219 HeapWord* start = _hrm.reserved().start();
2220 HeapWord* end = _hrm.reserved().end();
2221 size_t granularity = HeapRegion::GrainBytes;
2222
2223 _in_cset_fast_test.initialize(start, end, granularity);
2224 _humongous_reclaim_candidates.initialize(start, end, granularity);
2225 }
2226
2227 // Create the ConcurrentMark data structure and thread.
2228 // (Must do this late, so that "max_regions" is defined.)
2229 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2230 if (_cm == NULL || !_cm->completed_initialization()) {
2231 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2232 return JNI_ENOMEM;
2233 }
2234 _cmThread = _cm->cmThread();
2235
2236 // Initialize the from_card cache structure of HeapRegionRemSet.
2237 HeapRegionRemSet::init_heap(max_regions());
2238
2239 // Now expand into the initial heap size.
2240 if (!expand(init_byte_size)) {
2241 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2242 return JNI_ENOMEM;
2243 }
2244
2245 // Perform any initialization actions delegated to the policy.
2246 g1_policy()->init();
2247
2248 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2249 SATB_Q_FL_lock,
2250 G1SATBProcessCompletedThreshold,
2251 Shared_SATB_Q_lock);
2252
2253 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2254 DirtyCardQ_CBL_mon,
2255 DirtyCardQ_FL_lock,
2256 concurrent_g1_refine()->yellow_zone(),
2257 concurrent_g1_refine()->red_zone(),
2258 Shared_DirtyCardQ_lock);
2259
2260 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2261 DirtyCardQ_CBL_mon,
2262 DirtyCardQ_FL_lock,
2263 -1, // never trigger processing
2264 -1, // no limit on length
2265 Shared_DirtyCardQ_lock,
2266 &JavaThread::dirty_card_queue_set());
2267
2268 // Initialize the card queue set used to hold cards containing
2269 // references into the collection set.
2270 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2271 DirtyCardQ_CBL_mon,
2272 DirtyCardQ_FL_lock,
2273 -1, // never trigger processing
2274 -1, // no limit on length
2275 Shared_DirtyCardQ_lock,
2276 &JavaThread::dirty_card_queue_set());
2277
2278 // Here we allocate the dummy HeapRegion that is required by the
2279 // G1AllocRegion class.
2280 HeapRegion* dummy_region = _hrm.get_dummy_region();
2281
2282 // We'll re-use the same region whether the alloc region will
2283 // require BOT updates or not and, if it doesn't, then a non-young
2284 // region will complain that it cannot support allocations without
2285 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2286 dummy_region->set_eden();
2287 // Make sure it's full.
2288 dummy_region->set_top(dummy_region->end());
2289 G1AllocRegion::setup(this, dummy_region);
2290
2291 _allocator->init_mutator_alloc_region();
2292
2293 // Do create of the monitoring and management support so that
2294 // values in the heap have been properly initialized.
2295 _g1mm = new G1MonitoringSupport(this);
2296
2297 G1StringDedup::initialize();
2298
2299 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2300 for (uint i = 0; i < ParallelGCThreads; i++) {
2301 new (&_preserved_objs[i]) OopAndMarkOopStack();
2302 }
2303
2304 return JNI_OK;
2305 }
2306
2307 void G1CollectedHeap::stop() {
2308 // Stop all concurrent threads. We do this to make sure these threads
2309 // do not continue to execute and access resources (e.g. gclog_or_tty)
2310 // that are destroyed during shutdown.
2311 _cg1r->stop();
2312 _cmThread->stop();
2313 if (G1StringDedup::is_enabled()) {
2314 G1StringDedup::stop();
2315 }
2316 }
2317
2318 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2319 return HeapRegion::max_region_size();
2320 }
2321
2322 void G1CollectedHeap::post_initialize() {
2323 CollectedHeap::post_initialize();
2324 ref_processing_init();
2325 }
2326
2327 void G1CollectedHeap::ref_processing_init() {
2328 // Reference processing in G1 currently works as follows:
2329 //
2330 // * There are two reference processor instances. One is
2331 // used to record and process discovered references
2332 // during concurrent marking; the other is used to
2333 // record and process references during STW pauses
2334 // (both full and incremental).
2335 // * Both ref processors need to 'span' the entire heap as
2336 // the regions in the collection set may be dotted around.
2337 //
2338 // * For the concurrent marking ref processor:
2339 // * Reference discovery is enabled at initial marking.
2340 // * Reference discovery is disabled and the discovered
2341 // references processed etc during remarking.
2342 // * Reference discovery is MT (see below).
2343 // * Reference discovery requires a barrier (see below).
2344 // * Reference processing may or may not be MT
2345 // (depending on the value of ParallelRefProcEnabled
2346 // and ParallelGCThreads).
2347 // * A full GC disables reference discovery by the CM
2348 // ref processor and abandons any entries on it's
2349 // discovered lists.
2350 //
2351 // * For the STW processor:
2352 // * Non MT discovery is enabled at the start of a full GC.
2353 // * Processing and enqueueing during a full GC is non-MT.
2354 // * During a full GC, references are processed after marking.
2355 //
2356 // * Discovery (may or may not be MT) is enabled at the start
2357 // of an incremental evacuation pause.
2358 // * References are processed near the end of a STW evacuation pause.
2359 // * For both types of GC:
2360 // * Discovery is atomic - i.e. not concurrent.
2361 // * Reference discovery will not need a barrier.
2362
2363 MemRegion mr = reserved_region();
2364
2365 // Concurrent Mark ref processor
2366 _ref_processor_cm =
2367 new ReferenceProcessor(mr, // span
2368 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2369 // mt processing
2370 ParallelGCThreads,
2371 // degree of mt processing
2372 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2373 // mt discovery
2374 MAX2(ParallelGCThreads, ConcGCThreads),
2375 // degree of mt discovery
2376 false,
2377 // Reference discovery is not atomic
2378 &_is_alive_closure_cm);
2379 // is alive closure
2380 // (for efficiency/performance)
2381
2382 // STW ref processor
2383 _ref_processor_stw =
2384 new ReferenceProcessor(mr, // span
2385 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2386 // mt processing
2387 ParallelGCThreads,
2388 // degree of mt processing
2389 (ParallelGCThreads > 1),
2390 // mt discovery
2391 ParallelGCThreads,
2392 // degree of mt discovery
2393 true,
2394 // Reference discovery is atomic
2395 &_is_alive_closure_stw);
2396 // is alive closure
2397 // (for efficiency/performance)
2398 }
2399
2400 size_t G1CollectedHeap::capacity() const {
2401 return _hrm.length() * HeapRegion::GrainBytes;
2402 }
2403
2404 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2405 assert(!hr->is_continues_humongous(), "pre-condition");
2406 hr->reset_gc_time_stamp();
2407 if (hr->is_starts_humongous()) {
2408 uint first_index = hr->hrm_index() + 1;
2409 uint last_index = hr->last_hc_index();
2410 for (uint i = first_index; i < last_index; i += 1) {
2411 HeapRegion* chr = region_at(i);
2412 assert(chr->is_continues_humongous(), "sanity");
2413 chr->reset_gc_time_stamp();
2414 }
2415 }
2416 }
2417
2418 #ifndef PRODUCT
2419
2420 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2421 private:
2422 unsigned _gc_time_stamp;
2423 bool _failures;
2424
2425 public:
2426 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2427 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2428
2429 virtual bool doHeapRegion(HeapRegion* hr) {
2430 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2431 if (_gc_time_stamp != region_gc_time_stamp) {
2432 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2433 "expected %d", HR_FORMAT_PARAMS(hr),
2434 region_gc_time_stamp, _gc_time_stamp);
2435 _failures = true;
2436 }
2437 return false;
2438 }
2439
2440 bool failures() { return _failures; }
2441 };
2442
2443 void G1CollectedHeap::check_gc_time_stamps() {
2444 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2445 heap_region_iterate(&cl);
2446 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2447 }
2448 #endif // PRODUCT
2449
2450 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2451 DirtyCardQueue* into_cset_dcq,
2452 bool concurrent,
2453 uint worker_i) {
2454 // Clean cards in the hot card cache
2455 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2456 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2457
2458 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2459 size_t n_completed_buffers = 0;
2460 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2461 n_completed_buffers++;
2462 }
2463 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2464 dcqs.clear_n_completed_buffers();
2465 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2466 }
2467
2468 // Computes the sum of the storage used by the various regions.
2469 size_t G1CollectedHeap::used() const {
2470 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2471 if (_archive_allocator != NULL) {
2472 result += _archive_allocator->used();
2473 }
2474 return result;
2475 }
2476
2477 size_t G1CollectedHeap::used_unlocked() const {
2478 return _summary_bytes_used;
2479 }
2480
2481 class SumUsedClosure: public HeapRegionClosure {
2482 size_t _used;
2483 public:
2484 SumUsedClosure() : _used(0) {}
2485 bool doHeapRegion(HeapRegion* r) {
2486 if (!r->is_continues_humongous()) {
2487 _used += r->used();
2488 }
2489 return false;
2490 }
2491 size_t result() { return _used; }
2492 };
2493
2494 size_t G1CollectedHeap::recalculate_used() const {
2495 double recalculate_used_start = os::elapsedTime();
2496
2497 SumUsedClosure blk;
2498 heap_region_iterate(&blk);
2499
2500 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2501 return blk.result();
2502 }
2503
2504 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2505 switch (cause) {
2506 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2507 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2508 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2509 case GCCause::_g1_humongous_allocation: return true;
2510 case GCCause::_update_allocation_context_stats_inc: return true;
2511 case GCCause::_wb_conc_mark: return true;
2512 default: return false;
2513 }
2514 }
2515
2516 #ifndef PRODUCT
2517 void G1CollectedHeap::allocate_dummy_regions() {
2518 // Let's fill up most of the region
2519 size_t word_size = HeapRegion::GrainWords - 1024;
2520 // And as a result the region we'll allocate will be humongous.
2521 guarantee(is_humongous(word_size), "sanity");
2522
2523 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2524 // Let's use the existing mechanism for the allocation
2525 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2526 AllocationContext::system());
2527 if (dummy_obj != NULL) {
2528 MemRegion mr(dummy_obj, word_size);
2529 CollectedHeap::fill_with_object(mr);
2530 } else {
2531 // If we can't allocate once, we probably cannot allocate
2532 // again. Let's get out of the loop.
2533 break;
2534 }
2535 }
2536 }
2537 #endif // !PRODUCT
2538
2539 void G1CollectedHeap::increment_old_marking_cycles_started() {
2540 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2541 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2542 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2543 _old_marking_cycles_started, _old_marking_cycles_completed));
2544
2545 _old_marking_cycles_started++;
2546 }
2547
2548 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2549 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2550
2551 // We assume that if concurrent == true, then the caller is a
2552 // concurrent thread that was joined the Suspendible Thread
2553 // Set. If there's ever a cheap way to check this, we should add an
2554 // assert here.
2555
2556 // Given that this method is called at the end of a Full GC or of a
2557 // concurrent cycle, and those can be nested (i.e., a Full GC can
2558 // interrupt a concurrent cycle), the number of full collections
2559 // completed should be either one (in the case where there was no
2560 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2561 // behind the number of full collections started.
2562
2563 // This is the case for the inner caller, i.e. a Full GC.
2564 assert(concurrent ||
2565 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2566 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2567 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2568 "is inconsistent with _old_marking_cycles_completed = %u",
2569 _old_marking_cycles_started, _old_marking_cycles_completed));
2570
2571 // This is the case for the outer caller, i.e. the concurrent cycle.
2572 assert(!concurrent ||
2573 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2574 err_msg("for outer caller (concurrent cycle): "
2575 "_old_marking_cycles_started = %u "
2576 "is inconsistent with _old_marking_cycles_completed = %u",
2577 _old_marking_cycles_started, _old_marking_cycles_completed));
2578
2579 _old_marking_cycles_completed += 1;
2580
2581 // We need to clear the "in_progress" flag in the CM thread before
2582 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2583 // is set) so that if a waiter requests another System.gc() it doesn't
2584 // incorrectly see that a marking cycle is still in progress.
2585 if (concurrent) {
2586 _cmThread->set_idle();
2587 }
2588
2589 // This notify_all() will ensure that a thread that called
2590 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2591 // and it's waiting for a full GC to finish will be woken up. It is
2592 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2593 FullGCCount_lock->notify_all();
2594 }
2595
2596 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2597 collector_state()->set_concurrent_cycle_started(true);
2598 _gc_timer_cm->register_gc_start(start_time);
2599
2600 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2601 trace_heap_before_gc(_gc_tracer_cm);
2602 }
2603
2604 void G1CollectedHeap::register_concurrent_cycle_end() {
2605 if (collector_state()->concurrent_cycle_started()) {
2606 if (_cm->has_aborted()) {
2607 _gc_tracer_cm->report_concurrent_mode_failure();
2608 }
2609
2610 _gc_timer_cm->register_gc_end();
2611 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2612
2613 // Clear state variables to prepare for the next concurrent cycle.
2614 collector_state()->set_concurrent_cycle_started(false);
2615 _heap_summary_sent = false;
2616 }
2617 }
2618
2619 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2620 if (collector_state()->concurrent_cycle_started()) {
2621 // This function can be called when:
2622 // the cleanup pause is run
2623 // the concurrent cycle is aborted before the cleanup pause.
2624 // the concurrent cycle is aborted after the cleanup pause,
2625 // but before the concurrent cycle end has been registered.
2626 // Make sure that we only send the heap information once.
2627 if (!_heap_summary_sent) {
2628 trace_heap_after_gc(_gc_tracer_cm);
2629 _heap_summary_sent = true;
2630 }
2631 }
2632 }
2633
2634 void G1CollectedHeap::collect(GCCause::Cause cause) {
2635 assert_heap_not_locked();
2636
2637 uint gc_count_before;
2638 uint old_marking_count_before;
2639 uint full_gc_count_before;
2640 bool retry_gc;
2641
2642 do {
2643 retry_gc = false;
2644
2645 {
2646 MutexLocker ml(Heap_lock);
2647
2648 // Read the GC count while holding the Heap_lock
2649 gc_count_before = total_collections();
2650 full_gc_count_before = total_full_collections();
2651 old_marking_count_before = _old_marking_cycles_started;
2652 }
2653
2654 if (should_do_concurrent_full_gc(cause)) {
2655 // Schedule an initial-mark evacuation pause that will start a
2656 // concurrent cycle. We're setting word_size to 0 which means that
2657 // we are not requesting a post-GC allocation.
2658 VM_G1IncCollectionPause op(gc_count_before,
2659 0, /* word_size */
2660 true, /* should_initiate_conc_mark */
2661 g1_policy()->max_pause_time_ms(),
2662 cause);
2663 op.set_allocation_context(AllocationContext::current());
2664
2665 VMThread::execute(&op);
2666 if (!op.pause_succeeded()) {
2667 if (old_marking_count_before == _old_marking_cycles_started) {
2668 retry_gc = op.should_retry_gc();
2669 } else {
2670 // A Full GC happened while we were trying to schedule the
2671 // initial-mark GC. No point in starting a new cycle given
2672 // that the whole heap was collected anyway.
2673 }
2674
2675 if (retry_gc) {
2676 if (GC_locker::is_active_and_needs_gc()) {
2677 GC_locker::stall_until_clear();
2678 }
2679 }
2680 }
2681 } else {
2682 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2683 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2684
2685 // Schedule a standard evacuation pause. We're setting word_size
2686 // to 0 which means that we are not requesting a post-GC allocation.
2687 VM_G1IncCollectionPause op(gc_count_before,
2688 0, /* word_size */
2689 false, /* should_initiate_conc_mark */
2690 g1_policy()->max_pause_time_ms(),
2691 cause);
2692 VMThread::execute(&op);
2693 } else {
2694 // Schedule a Full GC.
2695 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2696 VMThread::execute(&op);
2697 }
2698 }
2699 } while (retry_gc);
2700 }
2701
2702 bool G1CollectedHeap::is_in(const void* p) const {
2703 if (_hrm.reserved().contains(p)) {
2704 // Given that we know that p is in the reserved space,
2705 // heap_region_containing_raw() should successfully
2706 // return the containing region.
2707 HeapRegion* hr = heap_region_containing_raw(p);
2708 return hr->is_in(p);
2709 } else {
2710 return false;
2711 }
2712 }
2713
2714 #ifdef ASSERT
2715 bool G1CollectedHeap::is_in_exact(const void* p) const {
2716 bool contains = reserved_region().contains(p);
2717 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2718 if (contains && available) {
2719 return true;
2720 } else {
2721 return false;
2722 }
2723 }
2724 #endif
2725
2726 bool G1CollectedHeap::obj_in_cs(oop obj) {
2727 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2728 return r != NULL && r->in_collection_set();
2729 }
2730
2731 // Iteration functions.
2732
2733 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2734
2735 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2736 ExtendedOopClosure* _cl;
2737 public:
2738 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2739 bool doHeapRegion(HeapRegion* r) {
2740 if (!r->is_continues_humongous()) {
2741 r->oop_iterate(_cl);
2742 }
2743 return false;
2744 }
2745 };
2746
2747 // Iterates an ObjectClosure over all objects within a HeapRegion.
2748
2749 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2750 ObjectClosure* _cl;
2751 public:
2752 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2753 bool doHeapRegion(HeapRegion* r) {
2754 if (!r->is_continues_humongous()) {
2755 r->object_iterate(_cl);
2756 }
2757 return false;
2758 }
2759 };
2760
2761 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2762 IterateObjectClosureRegionClosure blk(cl);
2763 heap_region_iterate(&blk);
2764 }
2765
2766 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2767 _hrm.iterate(cl);
2768 }
2769
2770 void
2771 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2772 uint worker_id,
2773 HeapRegionClaimer *hrclaimer,
2774 bool concurrent) const {
2775 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2776 }
2777
2778 // Clear the cached CSet starting regions and (more importantly)
2779 // the time stamps. Called when we reset the GC time stamp.
2780 void G1CollectedHeap::clear_cset_start_regions() {
2781 assert(_worker_cset_start_region != NULL, "sanity");
2782 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2783
2784 for (uint i = 0; i < ParallelGCThreads; i++) {
2785 _worker_cset_start_region[i] = NULL;
2786 _worker_cset_start_region_time_stamp[i] = 0;
2787 }
2788 }
2789
2790 // Given the id of a worker, obtain or calculate a suitable
2791 // starting region for iterating over the current collection set.
2792 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2793 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2794
2795 HeapRegion* result = NULL;
2796 unsigned gc_time_stamp = get_gc_time_stamp();
2797
2798 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2799 // Cached starting region for current worker was set
2800 // during the current pause - so it's valid.
2801 // Note: the cached starting heap region may be NULL
2802 // (when the collection set is empty).
2803 result = _worker_cset_start_region[worker_i];
2804 assert(result == NULL || result->in_collection_set(), "sanity");
2805 return result;
2806 }
2807
2808 // The cached entry was not valid so let's calculate
2809 // a suitable starting heap region for this worker.
2810
2811 // We want the parallel threads to start their collection
2812 // set iteration at different collection set regions to
2813 // avoid contention.
2814 // If we have:
2815 // n collection set regions
2816 // p threads
2817 // Then thread t will start at region floor ((t * n) / p)
2818
2819 result = g1_policy()->collection_set();
2820 uint cs_size = g1_policy()->cset_region_length();
2821 uint active_workers = workers()->active_workers();
2822
2823 uint end_ind = (cs_size * worker_i) / active_workers;
2824 uint start_ind = 0;
2825
2826 if (worker_i > 0 &&
2827 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2828 // Previous workers starting region is valid
2829 // so let's iterate from there
2830 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2831 result = _worker_cset_start_region[worker_i - 1];
2832 }
2833
2834 for (uint i = start_ind; i < end_ind; i++) {
2835 result = result->next_in_collection_set();
2836 }
2837
2838 // Note: the calculated starting heap region may be NULL
2839 // (when the collection set is empty).
2840 assert(result == NULL || result->in_collection_set(), "sanity");
2841 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2842 "should be updated only once per pause");
2843 _worker_cset_start_region[worker_i] = result;
2844 OrderAccess::storestore();
2845 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2846 return result;
2847 }
2848
2849 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2850 HeapRegion* r = g1_policy()->collection_set();
2851 while (r != NULL) {
2852 HeapRegion* next = r->next_in_collection_set();
2853 if (cl->doHeapRegion(r)) {
2854 cl->incomplete();
2855 return;
2856 }
2857 r = next;
2858 }
2859 }
2860
2861 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2862 HeapRegionClosure *cl) {
2863 if (r == NULL) {
2864 // The CSet is empty so there's nothing to do.
2865 return;
2866 }
2867
2868 assert(r->in_collection_set(),
2869 "Start region must be a member of the collection set.");
2870 HeapRegion* cur = r;
2871 while (cur != NULL) {
2872 HeapRegion* next = cur->next_in_collection_set();
2873 if (cl->doHeapRegion(cur) && false) {
2874 cl->incomplete();
2875 return;
2876 }
2877 cur = next;
2878 }
2879 cur = g1_policy()->collection_set();
2880 while (cur != r) {
2881 HeapRegion* next = cur->next_in_collection_set();
2882 if (cl->doHeapRegion(cur) && false) {
2883 cl->incomplete();
2884 return;
2885 }
2886 cur = next;
2887 }
2888 }
2889
2890 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2891 HeapRegion* result = _hrm.next_region_in_heap(from);
2892 while (result != NULL && result->is_pinned()) {
2893 result = _hrm.next_region_in_heap(result);
2894 }
2895 return result;
2896 }
2897
2898 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2899 HeapRegion* hr = heap_region_containing(addr);
2900 return hr->block_start(addr);
2901 }
2902
2903 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2904 HeapRegion* hr = heap_region_containing(addr);
2905 return hr->block_size(addr);
2906 }
2907
2908 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2909 HeapRegion* hr = heap_region_containing(addr);
2910 return hr->block_is_obj(addr);
2911 }
2912
2913 bool G1CollectedHeap::supports_tlab_allocation() const {
2914 return true;
2915 }
2916
2917 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2918 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2919 }
2920
2921 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2922 return young_list()->eden_used_bytes();
2923 }
2924
2925 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2926 // must be smaller than the humongous object limit.
2927 size_t G1CollectedHeap::max_tlab_size() const {
2928 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2929 }
2930
2931 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2932 AllocationContext_t context = AllocationContext::current();
2933 return _allocator->unsafe_max_tlab_alloc(context);
2934 }
2935
2936 size_t G1CollectedHeap::max_capacity() const {
2937 return _hrm.reserved().byte_size();
2938 }
2939
2940 jlong G1CollectedHeap::millis_since_last_gc() {
2941 // assert(false, "NYI");
2942 return 0;
2943 }
2944
2945 void G1CollectedHeap::prepare_for_verify() {
2946 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2947 ensure_parsability(false);
2948 }
2949 g1_rem_set()->prepare_for_verify();
2950 }
2951
2952 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2953 VerifyOption vo) {
2954 switch (vo) {
2955 case VerifyOption_G1UsePrevMarking:
2956 return hr->obj_allocated_since_prev_marking(obj);
2957 case VerifyOption_G1UseNextMarking:
2958 return hr->obj_allocated_since_next_marking(obj);
2959 case VerifyOption_G1UseMarkWord:
2960 return false;
2961 default:
2962 ShouldNotReachHere();
2963 }
2964 return false; // keep some compilers happy
2965 }
2966
2967 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2968 switch (vo) {
2969 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2970 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2971 case VerifyOption_G1UseMarkWord: return NULL;
2972 default: ShouldNotReachHere();
2973 }
2974 return NULL; // keep some compilers happy
2975 }
2976
2977 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2978 switch (vo) {
2979 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2980 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2981 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2982 default: ShouldNotReachHere();
2983 }
2984 return false; // keep some compilers happy
2985 }
2986
2987 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2988 switch (vo) {
2989 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2990 case VerifyOption_G1UseNextMarking: return "NTAMS";
2991 case VerifyOption_G1UseMarkWord: return "NONE";
2992 default: ShouldNotReachHere();
2993 }
2994 return NULL; // keep some compilers happy
2995 }
2996
2997 class VerifyRootsClosure: public OopClosure {
2998 private:
2999 G1CollectedHeap* _g1h;
3000 VerifyOption _vo;
3001 bool _failures;
3002 public:
3003 // _vo == UsePrevMarking -> use "prev" marking information,
3004 // _vo == UseNextMarking -> use "next" marking information,
3005 // _vo == UseMarkWord -> use mark word from object header.
3006 VerifyRootsClosure(VerifyOption vo) :
3007 _g1h(G1CollectedHeap::heap()),
3008 _vo(vo),
3009 _failures(false) { }
3010
3011 bool failures() { return _failures; }
3012
3013 template <class T> void do_oop_nv(T* p) {
3014 T heap_oop = oopDesc::load_heap_oop(p);
3015 if (!oopDesc::is_null(heap_oop)) {
3016 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3017 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3018 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3019 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3020 if (_vo == VerifyOption_G1UseMarkWord) {
3021 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3022 }
3023 obj->print_on(gclog_or_tty);
3024 _failures = true;
3025 }
3026 }
3027 }
3028
3029 void do_oop(oop* p) { do_oop_nv(p); }
3030 void do_oop(narrowOop* p) { do_oop_nv(p); }
3031 };
3032
3033 class G1VerifyCodeRootOopClosure: public OopClosure {
3034 G1CollectedHeap* _g1h;
3035 OopClosure* _root_cl;
3036 nmethod* _nm;
3037 VerifyOption _vo;
3038 bool _failures;
3039
3040 template <class T> void do_oop_work(T* p) {
3041 // First verify that this root is live
3042 _root_cl->do_oop(p);
3043
3044 if (!G1VerifyHeapRegionCodeRoots) {
3045 // We're not verifying the code roots attached to heap region.
3046 return;
3047 }
3048
3049 // Don't check the code roots during marking verification in a full GC
3050 if (_vo == VerifyOption_G1UseMarkWord) {
3051 return;
3052 }
3053
3054 // Now verify that the current nmethod (which contains p) is
3055 // in the code root list of the heap region containing the
3056 // object referenced by p.
3057
3058 T heap_oop = oopDesc::load_heap_oop(p);
3059 if (!oopDesc::is_null(heap_oop)) {
3060 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3061
3062 // Now fetch the region containing the object
3063 HeapRegion* hr = _g1h->heap_region_containing(obj);
3064 HeapRegionRemSet* hrrs = hr->rem_set();
3065 // Verify that the strong code root list for this region
3066 // contains the nmethod
3067 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3068 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3069 "from nmethod " PTR_FORMAT " not in strong "
3070 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3071 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3072 _failures = true;
3073 }
3074 }
3075 }
3076
3077 public:
3078 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3079 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3080
3081 void do_oop(oop* p) { do_oop_work(p); }
3082 void do_oop(narrowOop* p) { do_oop_work(p); }
3083
3084 void set_nmethod(nmethod* nm) { _nm = nm; }
3085 bool failures() { return _failures; }
3086 };
3087
3088 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3089 G1VerifyCodeRootOopClosure* _oop_cl;
3090
3091 public:
3092 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3093 _oop_cl(oop_cl) {}
3094
3095 void do_code_blob(CodeBlob* cb) {
3096 nmethod* nm = cb->as_nmethod_or_null();
3097 if (nm != NULL) {
3098 _oop_cl->set_nmethod(nm);
3099 nm->oops_do(_oop_cl);
3100 }
3101 }
3102 };
3103
3104 class YoungRefCounterClosure : public OopClosure {
3105 G1CollectedHeap* _g1h;
3106 int _count;
3107 public:
3108 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3109 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3110 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3111
3112 int count() { return _count; }
3113 void reset_count() { _count = 0; };
3114 };
3115
3116 class VerifyKlassClosure: public KlassClosure {
3117 YoungRefCounterClosure _young_ref_counter_closure;
3118 OopClosure *_oop_closure;
3119 public:
3120 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3121 void do_klass(Klass* k) {
3122 k->oops_do(_oop_closure);
3123
3124 _young_ref_counter_closure.reset_count();
3125 k->oops_do(&_young_ref_counter_closure);
3126 if (_young_ref_counter_closure.count() > 0) {
3127 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3128 }
3129 }
3130 };
3131
3132 class VerifyLivenessOopClosure: public OopClosure {
3133 G1CollectedHeap* _g1h;
3134 VerifyOption _vo;
3135 public:
3136 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3137 _g1h(g1h), _vo(vo)
3138 { }
3139 void do_oop(narrowOop *p) { do_oop_work(p); }
3140 void do_oop( oop *p) { do_oop_work(p); }
3141
3142 template <class T> void do_oop_work(T *p) {
3143 oop obj = oopDesc::load_decode_heap_oop(p);
3144 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3145 "Dead object referenced by a not dead object");
3146 }
3147 };
3148
3149 class VerifyObjsInRegionClosure: public ObjectClosure {
3150 private:
3151 G1CollectedHeap* _g1h;
3152 size_t _live_bytes;
3153 HeapRegion *_hr;
3154 VerifyOption _vo;
3155 public:
3156 // _vo == UsePrevMarking -> use "prev" marking information,
3157 // _vo == UseNextMarking -> use "next" marking information,
3158 // _vo == UseMarkWord -> use mark word from object header.
3159 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3160 : _live_bytes(0), _hr(hr), _vo(vo) {
3161 _g1h = G1CollectedHeap::heap();
3162 }
3163 void do_object(oop o) {
3164 VerifyLivenessOopClosure isLive(_g1h, _vo);
3165 assert(o != NULL, "Huh?");
3166 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3167 // If the object is alive according to the mark word,
3168 // then verify that the marking information agrees.
3169 // Note we can't verify the contra-positive of the
3170 // above: if the object is dead (according to the mark
3171 // word), it may not be marked, or may have been marked
3172 // but has since became dead, or may have been allocated
3173 // since the last marking.
3174 if (_vo == VerifyOption_G1UseMarkWord) {
3175 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3176 }
3177
3178 o->oop_iterate_no_header(&isLive);
3179 if (!_hr->obj_allocated_since_prev_marking(o)) {
3180 size_t obj_size = o->size(); // Make sure we don't overflow
3181 _live_bytes += (obj_size * HeapWordSize);
3182 }
3183 }
3184 }
3185 size_t live_bytes() { return _live_bytes; }
3186 };
3187
3188 class VerifyArchiveOopClosure: public OopClosure {
3189 public:
3190 VerifyArchiveOopClosure(HeapRegion *hr) { }
3191 void do_oop(narrowOop *p) { do_oop_work(p); }
3192 void do_oop( oop *p) { do_oop_work(p); }
3193
3194 template <class T> void do_oop_work(T *p) {
3195 oop obj = oopDesc::load_decode_heap_oop(p);
3196 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3197 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3198 p2i(p), p2i(obj)));
3199 }
3200 };
3201
3202 class VerifyArchiveRegionClosure: public ObjectClosure {
3203 public:
3204 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3205 // Verify that all object pointers are to archive regions.
3206 void do_object(oop o) {
3207 VerifyArchiveOopClosure checkOop(NULL);
3208 assert(o != NULL, "Should not be here for NULL oops");
3209 o->oop_iterate_no_header(&checkOop);
3210 }
3211 };
3212
3213 class VerifyRegionClosure: public HeapRegionClosure {
3214 private:
3215 bool _par;
3216 VerifyOption _vo;
3217 bool _failures;
3218 public:
3219 // _vo == UsePrevMarking -> use "prev" marking information,
3220 // _vo == UseNextMarking -> use "next" marking information,
3221 // _vo == UseMarkWord -> use mark word from object header.
3222 VerifyRegionClosure(bool par, VerifyOption vo)
3223 : _par(par),
3224 _vo(vo),
3225 _failures(false) {}
3226
3227 bool failures() {
3228 return _failures;
3229 }
3230
3231 bool doHeapRegion(HeapRegion* r) {
3232 // For archive regions, verify there are no heap pointers to
3233 // non-pinned regions. For all others, verify liveness info.
3234 if (r->is_archive()) {
3235 VerifyArchiveRegionClosure verify_oop_pointers(r);
3236 r->object_iterate(&verify_oop_pointers);
3237 return true;
3238 }
3239 if (!r->is_continues_humongous()) {
3240 bool failures = false;
3241 r->verify(_vo, &failures);
3242 if (failures) {
3243 _failures = true;
3244 } else {
3245 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3246 r->object_iterate(¬_dead_yet_cl);
3247 if (_vo != VerifyOption_G1UseNextMarking) {
3248 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3249 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3250 "max_live_bytes " SIZE_FORMAT " "
3251 "< calculated " SIZE_FORMAT,
3252 p2i(r->bottom()), p2i(r->end()),
3253 r->max_live_bytes(),
3254 not_dead_yet_cl.live_bytes());
3255 _failures = true;
3256 }
3257 } else {
3258 // When vo == UseNextMarking we cannot currently do a sanity
3259 // check on the live bytes as the calculation has not been
3260 // finalized yet.
3261 }
3262 }
3263 }
3264 return false; // stop the region iteration if we hit a failure
3265 }
3266 };
3267
3268 // This is the task used for parallel verification of the heap regions
3269
3270 class G1ParVerifyTask: public AbstractGangTask {
3271 private:
3272 G1CollectedHeap* _g1h;
3273 VerifyOption _vo;
3274 bool _failures;
3275 HeapRegionClaimer _hrclaimer;
3276
3277 public:
3278 // _vo == UsePrevMarking -> use "prev" marking information,
3279 // _vo == UseNextMarking -> use "next" marking information,
3280 // _vo == UseMarkWord -> use mark word from object header.
3281 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3282 AbstractGangTask("Parallel verify task"),
3283 _g1h(g1h),
3284 _vo(vo),
3285 _failures(false),
3286 _hrclaimer(g1h->workers()->active_workers()) {}
3287
3288 bool failures() {
3289 return _failures;
3290 }
3291
3292 void work(uint worker_id) {
3293 HandleMark hm;
3294 VerifyRegionClosure blk(true, _vo);
3295 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3296 if (blk.failures()) {
3297 _failures = true;
3298 }
3299 }
3300 };
3301
3302 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3303 if (SafepointSynchronize::is_at_safepoint()) {
3304 assert(Thread::current()->is_VM_thread(),
3305 "Expected to be executed serially by the VM thread at this point");
3306
3307 if (!silent) { gclog_or_tty->print("Roots "); }
3308 VerifyRootsClosure rootsCl(vo);
3309 VerifyKlassClosure klassCl(this, &rootsCl);
3310 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3311
3312 // We apply the relevant closures to all the oops in the
3313 // system dictionary, class loader data graph, the string table
3314 // and the nmethods in the code cache.
3315 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3316 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3317
3318 {
3319 G1RootProcessor root_processor(this, 1);
3320 root_processor.process_all_roots(&rootsCl,
3321 &cldCl,
3322 &blobsCl);
3323 }
3324
3325 bool failures = rootsCl.failures() || codeRootsCl.failures();
3326
3327 if (vo != VerifyOption_G1UseMarkWord) {
3328 // If we're verifying during a full GC then the region sets
3329 // will have been torn down at the start of the GC. Therefore
3330 // verifying the region sets will fail. So we only verify
3331 // the region sets when not in a full GC.
3332 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3333 verify_region_sets();
3334 }
3335
3336 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3337 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3338
3339 G1ParVerifyTask task(this, vo);
3340 workers()->run_task(&task);
3341 if (task.failures()) {
3342 failures = true;
3343 }
3344
3345 } else {
3346 VerifyRegionClosure blk(false, vo);
3347 heap_region_iterate(&blk);
3348 if (blk.failures()) {
3349 failures = true;
3350 }
3351 }
3352
3353 if (G1StringDedup::is_enabled()) {
3354 if (!silent) gclog_or_tty->print("StrDedup ");
3355 G1StringDedup::verify();
3356 }
3357
3358 if (failures) {
3359 gclog_or_tty->print_cr("Heap:");
3360 // It helps to have the per-region information in the output to
3361 // help us track down what went wrong. This is why we call
3362 // print_extended_on() instead of print_on().
3363 print_extended_on(gclog_or_tty);
3364 gclog_or_tty->cr();
3365 gclog_or_tty->flush();
3366 }
3367 guarantee(!failures, "there should not have been any failures");
3368 } else {
3369 if (!silent) {
3370 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3371 if (G1StringDedup::is_enabled()) {
3372 gclog_or_tty->print(", StrDedup");
3373 }
3374 gclog_or_tty->print(") ");
3375 }
3376 }
3377 }
3378
3379 void G1CollectedHeap::verify(bool silent) {
3380 verify(silent, VerifyOption_G1UsePrevMarking);
3381 }
3382
3383 double G1CollectedHeap::verify(bool guard, const char* msg) {
3384 double verify_time_ms = 0.0;
3385
3386 if (guard && total_collections() >= VerifyGCStartAt) {
3387 double verify_start = os::elapsedTime();
3388 HandleMark hm; // Discard invalid handles created during verification
3389 prepare_for_verify();
3390 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3391 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3392 }
3393
3394 return verify_time_ms;
3395 }
3396
3397 void G1CollectedHeap::verify_before_gc() {
3398 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3399 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3400 }
3401
3402 void G1CollectedHeap::verify_after_gc() {
3403 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3404 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3405 }
3406
3407 class PrintRegionClosure: public HeapRegionClosure {
3408 outputStream* _st;
3409 public:
3410 PrintRegionClosure(outputStream* st) : _st(st) {}
3411 bool doHeapRegion(HeapRegion* r) {
3412 r->print_on(_st);
3413 return false;
3414 }
3415 };
3416
3417 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3418 const HeapRegion* hr,
3419 const VerifyOption vo) const {
3420 switch (vo) {
3421 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3422 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3423 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3424 default: ShouldNotReachHere();
3425 }
3426 return false; // keep some compilers happy
3427 }
3428
3429 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3430 const VerifyOption vo) const {
3431 switch (vo) {
3432 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3433 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3434 case VerifyOption_G1UseMarkWord: {
3435 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3436 return !obj->is_gc_marked() && !hr->is_archive();
3437 }
3438 default: ShouldNotReachHere();
3439 }
3440 return false; // keep some compilers happy
3441 }
3442
3443 void G1CollectedHeap::print_on(outputStream* st) const {
3444 st->print(" %-20s", "garbage-first heap");
3445 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3446 capacity()/K, used_unlocked()/K);
3447 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3448 p2i(_hrm.reserved().start()),
3449 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3450 p2i(_hrm.reserved().end()));
3451 st->cr();
3452 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3453 uint young_regions = _young_list->length();
3454 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3455 (size_t) young_regions * HeapRegion::GrainBytes / K);
3456 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3457 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3458 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3459 st->cr();
3460 MetaspaceAux::print_on(st);
3461 }
3462
3463 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3464 print_on(st);
3465
3466 // Print the per-region information.
3467 st->cr();
3468 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3469 "HS=humongous(starts), HC=humongous(continues), "
3470 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3471 "PTAMS=previous top-at-mark-start, "
3472 "NTAMS=next top-at-mark-start)");
3473 PrintRegionClosure blk(st);
3474 heap_region_iterate(&blk);
3475 }
3476
3477 void G1CollectedHeap::print_on_error(outputStream* st) const {
3478 this->CollectedHeap::print_on_error(st);
3479
3480 if (_cm != NULL) {
3481 st->cr();
3482 _cm->print_on_error(st);
3483 }
3484 }
3485
3486 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3487 workers()->print_worker_threads_on(st);
3488 _cmThread->print_on(st);
3489 st->cr();
3490 _cm->print_worker_threads_on(st);
3491 _cg1r->print_worker_threads_on(st);
3492 if (G1StringDedup::is_enabled()) {
3493 G1StringDedup::print_worker_threads_on(st);
3494 }
3495 }
3496
3497 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3498 workers()->threads_do(tc);
3499 tc->do_thread(_cmThread);
3500 _cg1r->threads_do(tc);
3501 if (G1StringDedup::is_enabled()) {
3502 G1StringDedup::threads_do(tc);
3503 }
3504 }
3505
3506 void G1CollectedHeap::print_tracing_info() const {
3507 // We'll overload this to mean "trace GC pause statistics."
3508 if (TraceYoungGenTime || TraceOldGenTime) {
3509 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3510 // to that.
3511 g1_policy()->print_tracing_info();
3512 }
3513 if (G1SummarizeRSetStats) {
3514 g1_rem_set()->print_summary_info();
3515 }
3516 if (G1SummarizeConcMark) {
3517 concurrent_mark()->print_summary_info();
3518 }
3519 g1_policy()->print_yg_surv_rate_info();
3520 }
3521
3522 #ifndef PRODUCT
3523 // Helpful for debugging RSet issues.
3524
3525 class PrintRSetsClosure : public HeapRegionClosure {
3526 private:
3527 const char* _msg;
3528 size_t _occupied_sum;
3529
3530 public:
3531 bool doHeapRegion(HeapRegion* r) {
3532 HeapRegionRemSet* hrrs = r->rem_set();
3533 size_t occupied = hrrs->occupied();
3534 _occupied_sum += occupied;
3535
3536 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3537 HR_FORMAT_PARAMS(r));
3538 if (occupied == 0) {
3539 gclog_or_tty->print_cr(" RSet is empty");
3540 } else {
3541 hrrs->print();
3542 }
3543 gclog_or_tty->print_cr("----------");
3544 return false;
3545 }
3546
3547 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3548 gclog_or_tty->cr();
3549 gclog_or_tty->print_cr("========================================");
3550 gclog_or_tty->print_cr("%s", msg);
3551 gclog_or_tty->cr();
3552 }
3553
3554 ~PrintRSetsClosure() {
3555 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3556 gclog_or_tty->print_cr("========================================");
3557 gclog_or_tty->cr();
3558 }
3559 };
3560
3561 void G1CollectedHeap::print_cset_rsets() {
3562 PrintRSetsClosure cl("Printing CSet RSets");
3563 collection_set_iterate(&cl);
3564 }
3565
3566 void G1CollectedHeap::print_all_rsets() {
3567 PrintRSetsClosure cl("Printing All RSets");;
3568 heap_region_iterate(&cl);
3569 }
3570 #endif // PRODUCT
3571
3572 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3573 YoungList* young_list = heap()->young_list();
3574
3575 size_t eden_used_bytes = young_list->eden_used_bytes();
3576 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3577
3578 size_t eden_capacity_bytes =
3579 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3580
3581 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3582 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3583 }
3584
3585 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3586 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3587 stats->unused(), stats->used(), stats->region_end_waste(),
3588 stats->regions_filled(), stats->direct_allocated(),
3589 stats->failure_used(), stats->failure_waste());
3590 }
3591
3592 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3593 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3594 gc_tracer->report_gc_heap_summary(when, heap_summary);
3595
3596 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3597 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3598 }
3599
3600
3601 G1CollectedHeap* G1CollectedHeap::heap() {
3602 CollectedHeap* heap = Universe::heap();
3603 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3604 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3605 return (G1CollectedHeap*)heap;
3606 }
3607
3608 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3609 // always_do_update_barrier = false;
3610 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3611 // Fill TLAB's and such
3612 accumulate_statistics_all_tlabs();
3613 ensure_parsability(true);
3614
3615 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3616 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3617 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3618 }
3619 }
3620
3621 void G1CollectedHeap::gc_epilogue(bool full) {
3622
3623 if (G1SummarizeRSetStats &&
3624 (G1SummarizeRSetStatsPeriod > 0) &&
3625 // we are at the end of the GC. Total collections has already been increased.
3626 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3627 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3628 }
3629
3630 // FIXME: what is this about?
3631 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3632 // is set.
3633 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3634 "derived pointer present"));
3635 // always_do_update_barrier = true;
3636
3637 resize_all_tlabs();
3638 allocation_context_stats().update(full);
3639
3640 // We have just completed a GC. Update the soft reference
3641 // policy with the new heap occupancy
3642 Universe::update_heap_info_at_gc();
3643 }
3644
3645 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3646 uint gc_count_before,
3647 bool* succeeded,
3648 GCCause::Cause gc_cause) {
3649 assert_heap_not_locked_and_not_at_safepoint();
3650 g1_policy()->record_stop_world_start();
3651 VM_G1IncCollectionPause op(gc_count_before,
3652 word_size,
3653 false, /* should_initiate_conc_mark */
3654 g1_policy()->max_pause_time_ms(),
3655 gc_cause);
3656
3657 op.set_allocation_context(AllocationContext::current());
3658 VMThread::execute(&op);
3659
3660 HeapWord* result = op.result();
3661 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3662 assert(result == NULL || ret_succeeded,
3663 "the result should be NULL if the VM did not succeed");
3664 *succeeded = ret_succeeded;
3665
3666 assert_heap_not_locked();
3667 return result;
3668 }
3669
3670 void
3671 G1CollectedHeap::doConcurrentMark() {
3672 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3673 if (!_cmThread->in_progress()) {
3674 _cmThread->set_started();
3675 CGC_lock->notify();
3676 }
3677 }
3678
3679 size_t G1CollectedHeap::pending_card_num() {
3680 size_t extra_cards = 0;
3681 JavaThread *curr = Threads::first();
3682 while (curr != NULL) {
3683 DirtyCardQueue& dcq = curr->dirty_card_queue();
3684 extra_cards += dcq.size();
3685 curr = curr->next();
3686 }
3687 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3688 size_t buffer_size = dcqs.buffer_size();
3689 size_t buffer_num = dcqs.completed_buffers_num();
3690
3691 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3692 // in bytes - not the number of 'entries'. We need to convert
3693 // into a number of cards.
3694 return (buffer_size * buffer_num + extra_cards) / oopSize;
3695 }
3696
3697 size_t G1CollectedHeap::cards_scanned() {
3698 return g1_rem_set()->cardsScanned();
3699 }
3700
3701 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3702 private:
3703 size_t _total_humongous;
3704 size_t _candidate_humongous;
3705
3706 DirtyCardQueue _dcq;
3707
3708 // We don't nominate objects with many remembered set entries, on
3709 // the assumption that such objects are likely still live.
3710 bool is_remset_small(HeapRegion* region) const {
3711 HeapRegionRemSet* const rset = region->rem_set();
3712 return G1EagerReclaimHumongousObjectsWithStaleRefs
3713 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3714 : rset->is_empty();
3715 }
3716
3717 bool is_typeArray_region(HeapRegion* region) const {
3718 return oop(region->bottom())->is_typeArray();
3719 }
3720
3721 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3722 assert(region->is_starts_humongous(), "Must start a humongous object");
3723
3724 // Candidate selection must satisfy the following constraints
3725 // while concurrent marking is in progress:
3726 //
3727 // * In order to maintain SATB invariants, an object must not be
3728 // reclaimed if it was allocated before the start of marking and
3729 // has not had its references scanned. Such an object must have
3730 // its references (including type metadata) scanned to ensure no
3731 // live objects are missed by the marking process. Objects
3732 // allocated after the start of concurrent marking don't need to
3733 // be scanned.
3734 //
3735 // * An object must not be reclaimed if it is on the concurrent
3736 // mark stack. Objects allocated after the start of concurrent
3737 // marking are never pushed on the mark stack.
3738 //
3739 // Nominating only objects allocated after the start of concurrent
3740 // marking is sufficient to meet both constraints. This may miss
3741 // some objects that satisfy the constraints, but the marking data
3742 // structures don't support efficiently performing the needed
3743 // additional tests or scrubbing of the mark stack.
3744 //
3745 // However, we presently only nominate is_typeArray() objects.
3746 // A humongous object containing references induces remembered
3747 // set entries on other regions. In order to reclaim such an
3748 // object, those remembered sets would need to be cleaned up.
3749 //
3750 // We also treat is_typeArray() objects specially, allowing them
3751 // to be reclaimed even if allocated before the start of
3752 // concurrent mark. For this we rely on mark stack insertion to
3753 // exclude is_typeArray() objects, preventing reclaiming an object
3754 // that is in the mark stack. We also rely on the metadata for
3755 // such objects to be built-in and so ensured to be kept live.
3756 // Frequent allocation and drop of large binary blobs is an
3757 // important use case for eager reclaim, and this special handling
3758 // may reduce needed headroom.
3759
3760 return is_typeArray_region(region) && is_remset_small(region);
3761 }
3762
3763 public:
3764 RegisterHumongousWithInCSetFastTestClosure()
3765 : _total_humongous(0),
3766 _candidate_humongous(0),
3767 _dcq(&JavaThread::dirty_card_queue_set()) {
3768 }
3769
3770 virtual bool doHeapRegion(HeapRegion* r) {
3771 if (!r->is_starts_humongous()) {
3772 return false;
3773 }
3774 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3775
3776 bool is_candidate = humongous_region_is_candidate(g1h, r);
3777 uint rindex = r->hrm_index();
3778 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3779 if (is_candidate) {
3780 _candidate_humongous++;
3781 g1h->register_humongous_region_with_cset(rindex);
3782 // Is_candidate already filters out humongous object with large remembered sets.
3783 // If we have a humongous object with a few remembered sets, we simply flush these
3784 // remembered set entries into the DCQS. That will result in automatic
3785 // re-evaluation of their remembered set entries during the following evacuation
3786 // phase.
3787 if (!r->rem_set()->is_empty()) {
3788 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3789 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3790 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3791 HeapRegionRemSetIterator hrrs(r->rem_set());
3792 size_t card_index;
3793 while (hrrs.has_next(card_index)) {
3794 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3795 // The remembered set might contain references to already freed
3796 // regions. Filter out such entries to avoid failing card table
3797 // verification.
3798 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3799 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3800 *card_ptr = CardTableModRefBS::dirty_card_val();
3801 _dcq.enqueue(card_ptr);
3802 }
3803 }
3804 }
3805 r->rem_set()->clear_locked();
3806 }
3807 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3808 }
3809 _total_humongous++;
3810
3811 return false;
3812 }
3813
3814 size_t total_humongous() const { return _total_humongous; }
3815 size_t candidate_humongous() const { return _candidate_humongous; }
3816
3817 void flush_rem_set_entries() { _dcq.flush(); }
3818 };
3819
3820 void G1CollectedHeap::register_humongous_regions_with_cset() {
3821 if (!G1EagerReclaimHumongousObjects) {
3822 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3823 return;
3824 }
3825 double time = os::elapsed_counter();
3826
3827 // Collect reclaim candidate information and register candidates with cset.
3828 RegisterHumongousWithInCSetFastTestClosure cl;
3829 heap_region_iterate(&cl);
3830
3831 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3832 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3833 cl.total_humongous(),
3834 cl.candidate_humongous());
3835 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3836
3837 // Finally flush all remembered set entries to re-check into the global DCQS.
3838 cl.flush_rem_set_entries();
3839 }
3840
3841 void G1CollectedHeap::setup_surviving_young_words() {
3842 assert(_surviving_young_words == NULL, "pre-condition");
3843 uint array_length = g1_policy()->young_cset_region_length();
3844 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3845 if (_surviving_young_words == NULL) {
3846 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3847 "Not enough space for young surv words summary.");
3848 }
3849 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3850 #ifdef ASSERT
3851 for (uint i = 0; i < array_length; ++i) {
3852 assert( _surviving_young_words[i] == 0, "memset above" );
3853 }
3854 #endif // !ASSERT
3855 }
3856
3857 void G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3858 assert_at_safepoint(true);
3859 uint array_length = g1_policy()->young_cset_region_length();
3860 for (uint i = 0; i < array_length; ++i) {
3861 _surviving_young_words[i] += surv_young_words[i];
3862 }
3863 }
3864
3865 void G1CollectedHeap::cleanup_surviving_young_words() {
3866 guarantee( _surviving_young_words != NULL, "pre-condition" );
3867 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3868 _surviving_young_words = NULL;
3869 }
3870
3871 #ifdef ASSERT
3872 class VerifyCSetClosure: public HeapRegionClosure {
3873 public:
3874 bool doHeapRegion(HeapRegion* hr) {
3875 // Here we check that the CSet region's RSet is ready for parallel
3876 // iteration. The fields that we'll verify are only manipulated
3877 // when the region is part of a CSet and is collected. Afterwards,
3878 // we reset these fields when we clear the region's RSet (when the
3879 // region is freed) so they are ready when the region is
3880 // re-allocated. The only exception to this is if there's an
3881 // evacuation failure and instead of freeing the region we leave
3882 // it in the heap. In that case, we reset these fields during
3883 // evacuation failure handling.
3884 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3885
3886 // Here's a good place to add any other checks we'd like to
3887 // perform on CSet regions.
3888 return false;
3889 }
3890 };
3891 #endif // ASSERT
3892
3893 uint G1CollectedHeap::num_task_queues() const {
3894 return _task_queues->size();
3895 }
3896
3897 #if TASKQUEUE_STATS
3898 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3899 st->print_raw_cr("GC Task Stats");
3900 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3901 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3902 }
3903
3904 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3905 print_taskqueue_stats_hdr(st);
3906
3907 TaskQueueStats totals;
3908 const uint n = num_task_queues();
3909 for (uint i = 0; i < n; ++i) {
3910 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3911 totals += task_queue(i)->stats;
3912 }
3913 st->print_raw("tot "); totals.print(st); st->cr();
3914
3915 DEBUG_ONLY(totals.verify());
3916 }
3917
3918 void G1CollectedHeap::reset_taskqueue_stats() {
3919 const uint n = num_task_queues();
3920 for (uint i = 0; i < n; ++i) {
3921 task_queue(i)->stats.reset();
3922 }
3923 }
3924 #endif // TASKQUEUE_STATS
3925
3926 void G1CollectedHeap::log_gc_header() {
3927 if (!G1Log::fine()) {
3928 return;
3929 }
3930
3931 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3932
3933 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3934 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3935 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3936
3937 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3938 }
3939
3940 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3941 if (!G1Log::fine()) {
3942 return;
3943 }
3944
3945 if (G1Log::finer()) {
3946 if (evacuation_failed()) {
3947 gclog_or_tty->print(" (to-space exhausted)");
3948 }
3949 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3950 g1_policy()->phase_times()->note_gc_end();
3951 g1_policy()->phase_times()->print(pause_time_sec);
3952 g1_policy()->print_detailed_heap_transition();
3953 } else {
3954 if (evacuation_failed()) {
3955 gclog_or_tty->print("--");
3956 }
3957 g1_policy()->print_heap_transition();
3958 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3959 }
3960 gclog_or_tty->flush();
3961 }
3962
3963 void G1CollectedHeap::wait_for_root_region_scanning() {
3964 double scan_wait_start = os::elapsedTime();
3965 // We have to wait until the CM threads finish scanning the
3966 // root regions as it's the only way to ensure that all the
3967 // objects on them have been correctly scanned before we start
3968 // moving them during the GC.
3969 bool waited = _cm->root_regions()->wait_until_scan_finished();
3970 double wait_time_ms = 0.0;
3971 if (waited) {
3972 double scan_wait_end = os::elapsedTime();
3973 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3974 }
3975 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3976 }
3977
3978 bool
3979 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3980 assert_at_safepoint(true /* should_be_vm_thread */);
3981 guarantee(!is_gc_active(), "collection is not reentrant");
3982
3983 if (GC_locker::check_active_before_gc()) {
3984 return false;
3985 }
3986
3987 _gc_timer_stw->register_gc_start();
3988
3989 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3990
3991 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3992 ResourceMark rm;
3993
3994 wait_for_root_region_scanning();
3995
3996 G1Log::update_level();
3997 print_heap_before_gc();
3998 trace_heap_before_gc(_gc_tracer_stw);
3999
4000 verify_region_sets_optional();
4001 verify_dirty_young_regions();
4002
4003 // This call will decide whether this pause is an initial-mark
4004 // pause. If it is, during_initial_mark_pause() will return true
4005 // for the duration of this pause.
4006 g1_policy()->decide_on_conc_mark_initiation();
4007
4008 // We do not allow initial-mark to be piggy-backed on a mixed GC.
4009 assert(!collector_state()->during_initial_mark_pause() ||
4010 collector_state()->gcs_are_young(), "sanity");
4011
4012 // We also do not allow mixed GCs during marking.
4013 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4014
4015 // Record whether this pause is an initial mark. When the current
4016 // thread has completed its logging output and it's safe to signal
4017 // the CM thread, the flag's value in the policy has been reset.
4018 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4019
4020 // Inner scope for scope based logging, timers, and stats collection
4021 {
4022 EvacuationInfo evacuation_info;
4023
4024 if (collector_state()->during_initial_mark_pause()) {
4025 // We are about to start a marking cycle, so we increment the
4026 // full collection counter.
4027 increment_old_marking_cycles_started();
4028 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4029 }
4030
4031 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4032
4033 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4034
4035 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4036 workers()->active_workers(),
4037 Threads::number_of_non_daemon_threads());
4038 workers()->set_active_workers(active_workers);
4039
4040 double pause_start_sec = os::elapsedTime();
4041 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4042 log_gc_header();
4043
4044 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4045 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4046
4047 // If the secondary_free_list is not empty, append it to the
4048 // free_list. No need to wait for the cleanup operation to finish;
4049 // the region allocation code will check the secondary_free_list
4050 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4051 // set, skip this step so that the region allocation code has to
4052 // get entries from the secondary_free_list.
4053 if (!G1StressConcRegionFreeing) {
4054 append_secondary_free_list_if_not_empty_with_lock();
4055 }
4056
4057 assert(check_young_list_well_formed(), "young list should be well formed");
4058
4059 // Don't dynamically change the number of GC threads this early. A value of
4060 // 0 is used to indicate serial work. When parallel work is done,
4061 // it will be set.
4062
4063 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4064 IsGCActiveMark x;
4065
4066 gc_prologue(false);
4067 increment_total_collections(false /* full gc */);
4068 increment_gc_time_stamp();
4069
4070 verify_before_gc();
4071
4072 check_bitmaps("GC Start");
4073
4074 COMPILER2_PRESENT(DerivedPointerTable::clear());
4075
4076 // Please see comment in g1CollectedHeap.hpp and
4077 // G1CollectedHeap::ref_processing_init() to see how
4078 // reference processing currently works in G1.
4079
4080 // Enable discovery in the STW reference processor
4081 ref_processor_stw()->enable_discovery();
4082
4083 {
4084 // We want to temporarily turn off discovery by the
4085 // CM ref processor, if necessary, and turn it back on
4086 // on again later if we do. Using a scoped
4087 // NoRefDiscovery object will do this.
4088 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4089
4090 // Forget the current alloc region (we might even choose it to be part
4091 // of the collection set!).
4092 _allocator->release_mutator_alloc_region();
4093
4094 // We should call this after we retire the mutator alloc
4095 // region(s) so that all the ALLOC / RETIRE events are generated
4096 // before the start GC event.
4097 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4098
4099 // This timing is only used by the ergonomics to handle our pause target.
4100 // It is unclear why this should not include the full pause. We will
4101 // investigate this in CR 7178365.
4102 //
4103 // Preserving the old comment here if that helps the investigation:
4104 //
4105 // The elapsed time induced by the start time below deliberately elides
4106 // the possible verification above.
4107 double sample_start_time_sec = os::elapsedTime();
4108
4109 #if YOUNG_LIST_VERBOSE
4110 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4111 _young_list->print();
4112 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4113 #endif // YOUNG_LIST_VERBOSE
4114
4115 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4116
4117 #if YOUNG_LIST_VERBOSE
4118 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4119 _young_list->print();
4120 #endif // YOUNG_LIST_VERBOSE
4121
4122 if (collector_state()->during_initial_mark_pause()) {
4123 concurrent_mark()->checkpointRootsInitialPre();
4124 }
4125
4126 #if YOUNG_LIST_VERBOSE
4127 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4128 _young_list->print();
4129 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4130 #endif // YOUNG_LIST_VERBOSE
4131
4132 g1_policy()->finalize_cset(target_pause_time_ms);
4133
4134 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4135
4136 register_humongous_regions_with_cset();
4137
4138 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4139
4140 _cm->note_start_of_gc();
4141 // We call this after finalize_cset() to
4142 // ensure that the CSet has been finalized.
4143 _cm->verify_no_cset_oops();
4144
4145 if (_hr_printer.is_active()) {
4146 HeapRegion* hr = g1_policy()->collection_set();
4147 while (hr != NULL) {
4148 _hr_printer.cset(hr);
4149 hr = hr->next_in_collection_set();
4150 }
4151 }
4152
4153 #ifdef ASSERT
4154 VerifyCSetClosure cl;
4155 collection_set_iterate(&cl);
4156 #endif // ASSERT
4157
4158 setup_surviving_young_words();
4159
4160 // Initialize the GC alloc regions.
4161 _allocator->init_gc_alloc_regions(evacuation_info);
4162
4163 // Actually do the work...
4164 evacuate_collection_set(evacuation_info);
4165
4166 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4167
4168 eagerly_reclaim_humongous_regions();
4169
4170 g1_policy()->clear_collection_set();
4171
4172 cleanup_surviving_young_words();
4173
4174 // Start a new incremental collection set for the next pause.
4175 g1_policy()->start_incremental_cset_building();
4176
4177 clear_cset_fast_test();
4178
4179 _young_list->reset_sampled_info();
4180
4181 // Don't check the whole heap at this point as the
4182 // GC alloc regions from this pause have been tagged
4183 // as survivors and moved on to the survivor list.
4184 // Survivor regions will fail the !is_young() check.
4185 assert(check_young_list_empty(false /* check_heap */),
4186 "young list should be empty");
4187
4188 #if YOUNG_LIST_VERBOSE
4189 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4190 _young_list->print();
4191 #endif // YOUNG_LIST_VERBOSE
4192
4193 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4194 _young_list->first_survivor_region(),
4195 _young_list->last_survivor_region());
4196
4197 _young_list->reset_auxilary_lists();
4198
4199 if (evacuation_failed()) {
4200 set_used(recalculate_used());
4201 if (_archive_allocator != NULL) {
4202 _archive_allocator->clear_used();
4203 }
4204 for (uint i = 0; i < ParallelGCThreads; i++) {
4205 if (_evacuation_failed_info_array[i].has_failed()) {
4206 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4207 }
4208 }
4209 } else {
4210 // The "used" of the the collection set have already been subtracted
4211 // when they were freed. Add in the bytes evacuated.
4212 increase_used(g1_policy()->bytes_copied_during_gc());
4213 }
4214
4215 if (collector_state()->during_initial_mark_pause()) {
4216 // We have to do this before we notify the CM threads that
4217 // they can start working to make sure that all the
4218 // appropriate initialization is done on the CM object.
4219 concurrent_mark()->checkpointRootsInitialPost();
4220 collector_state()->set_mark_in_progress(true);
4221 // Note that we don't actually trigger the CM thread at
4222 // this point. We do that later when we're sure that
4223 // the current thread has completed its logging output.
4224 }
4225
4226 allocate_dummy_regions();
4227
4228 #if YOUNG_LIST_VERBOSE
4229 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4230 _young_list->print();
4231 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4232 #endif // YOUNG_LIST_VERBOSE
4233
4234 _allocator->init_mutator_alloc_region();
4235
4236 {
4237 size_t expand_bytes = g1_policy()->expansion_amount();
4238 if (expand_bytes > 0) {
4239 size_t bytes_before = capacity();
4240 // No need for an ergo verbose message here,
4241 // expansion_amount() does this when it returns a value > 0.
4242 if (!expand(expand_bytes)) {
4243 // We failed to expand the heap. Cannot do anything about it.
4244 }
4245 }
4246 }
4247
4248 // We redo the verification but now wrt to the new CSet which
4249 // has just got initialized after the previous CSet was freed.
4250 _cm->verify_no_cset_oops();
4251 _cm->note_end_of_gc();
4252
4253 // This timing is only used by the ergonomics to handle our pause target.
4254 // It is unclear why this should not include the full pause. We will
4255 // investigate this in CR 7178365.
4256 double sample_end_time_sec = os::elapsedTime();
4257 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4258 g1_policy()->record_collection_pause_end(pause_time_ms);
4259
4260 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4261 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4262
4263 MemoryService::track_memory_usage();
4264
4265 // In prepare_for_verify() below we'll need to scan the deferred
4266 // update buffers to bring the RSets up-to-date if
4267 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4268 // the update buffers we'll probably need to scan cards on the
4269 // regions we just allocated to (i.e., the GC alloc
4270 // regions). However, during the last GC we called
4271 // set_saved_mark() on all the GC alloc regions, so card
4272 // scanning might skip the [saved_mark_word()...top()] area of
4273 // those regions (i.e., the area we allocated objects into
4274 // during the last GC). But it shouldn't. Given that
4275 // saved_mark_word() is conditional on whether the GC time stamp
4276 // on the region is current or not, by incrementing the GC time
4277 // stamp here we invalidate all the GC time stamps on all the
4278 // regions and saved_mark_word() will simply return top() for
4279 // all the regions. This is a nicer way of ensuring this rather
4280 // than iterating over the regions and fixing them. In fact, the
4281 // GC time stamp increment here also ensures that
4282 // saved_mark_word() will return top() between pauses, i.e.,
4283 // during concurrent refinement. So we don't need the
4284 // is_gc_active() check to decided which top to use when
4285 // scanning cards (see CR 7039627).
4286 increment_gc_time_stamp();
4287
4288 verify_after_gc();
4289 check_bitmaps("GC End");
4290
4291 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4292 ref_processor_stw()->verify_no_references_recorded();
4293
4294 // CM reference discovery will be re-enabled if necessary.
4295 }
4296
4297 // We should do this after we potentially expand the heap so
4298 // that all the COMMIT events are generated before the end GC
4299 // event, and after we retire the GC alloc regions so that all
4300 // RETIRE events are generated before the end GC event.
4301 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4302
4303 #ifdef TRACESPINNING
4304 ParallelTaskTerminator::print_termination_counts();
4305 #endif
4306
4307 gc_epilogue(false);
4308 }
4309
4310 // Print the remainder of the GC log output.
4311 log_gc_footer(os::elapsedTime() - pause_start_sec);
4312
4313 // It is not yet to safe to tell the concurrent mark to
4314 // start as we have some optional output below. We don't want the
4315 // output from the concurrent mark thread interfering with this
4316 // logging output either.
4317
4318 _hrm.verify_optional();
4319 verify_region_sets_optional();
4320
4321 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4322 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4323
4324 print_heap_after_gc();
4325 trace_heap_after_gc(_gc_tracer_stw);
4326
4327 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4328 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4329 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4330 // before any GC notifications are raised.
4331 g1mm()->update_sizes();
4332
4333 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4334 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4335 _gc_timer_stw->register_gc_end();
4336 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4337 }
4338 // It should now be safe to tell the concurrent mark thread to start
4339 // without its logging output interfering with the logging output
4340 // that came from the pause.
4341
4342 if (should_start_conc_mark) {
4343 // CAUTION: after the doConcurrentMark() call below,
4344 // the concurrent marking thread(s) could be running
4345 // concurrently with us. Make sure that anything after
4346 // this point does not assume that we are the only GC thread
4347 // running. Note: of course, the actual marking work will
4348 // not start until the safepoint itself is released in
4349 // SuspendibleThreadSet::desynchronize().
4350 doConcurrentMark();
4351 }
4352
4353 return true;
4354 }
4355
4356 void G1CollectedHeap::remove_self_forwarding_pointers() {
4357 double remove_self_forwards_start = os::elapsedTime();
4358
4359 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4360 workers()->run_task(&rsfp_task);
4361
4362 // Now restore saved marks, if any.
4363 for (uint i = 0; i < ParallelGCThreads; i++) {
4364 OopAndMarkOopStack& cur = _preserved_objs[i];
4365 while (!cur.is_empty()) {
4366 OopAndMarkOop elem = cur.pop();
4367 elem.set_mark();
4368 }
4369 cur.clear(true);
4370 }
4371
4372 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4373 }
4374
4375 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4376 if (!_evacuation_failed) {
4377 _evacuation_failed = true;
4378 }
4379
4380 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4381
4382 // We want to call the "for_promotion_failure" version only in the
4383 // case of a promotion failure.
4384 if (m->must_be_preserved_for_promotion_failure(obj)) {
4385 OopAndMarkOop elem(obj, m);
4386 _preserved_objs[worker_id].push(elem);
4387 }
4388 }
4389
4390 void G1ParCopyHelper::mark_object(oop obj) {
4391 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4392
4393 // We know that the object is not moving so it's safe to read its size.
4394 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4395 }
4396
4397 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4398 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4399 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4400 assert(from_obj != to_obj, "should not be self-forwarded");
4401
4402 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4403 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4404
4405 // The object might be in the process of being copied by another
4406 // worker so we cannot trust that its to-space image is
4407 // well-formed. So we have to read its size from its from-space
4408 // image which we know should not be changing.
4409 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4410 }
4411
4412 template <class T>
4413 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4414 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4415 _scanned_klass->record_modified_oops();
4416 }
4417 }
4418
4419 template <G1Barrier barrier, G1Mark do_mark_object>
4420 template <class T>
4421 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4422 T heap_oop = oopDesc::load_heap_oop(p);
4423
4424 if (oopDesc::is_null(heap_oop)) {
4425 return;
4426 }
4427
4428 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4429
4430 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4431
4432 const InCSetState state = _g1->in_cset_state(obj);
4433 if (state.is_in_cset()) {
4434 oop forwardee;
4435 markOop m = obj->mark();
4436 if (m->is_marked()) {
4437 forwardee = (oop) m->decode_pointer();
4438 } else {
4439 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4440 }
4441 assert(forwardee != NULL, "forwardee should not be NULL");
4442 oopDesc::encode_store_heap_oop(p, forwardee);
4443 if (do_mark_object != G1MarkNone && forwardee != obj) {
4444 // If the object is self-forwarded we don't need to explicitly
4445 // mark it, the evacuation failure protocol will do so.
4446 mark_forwarded_object(obj, forwardee);
4447 }
4448
4449 if (barrier == G1BarrierKlass) {
4450 do_klass_barrier(p, forwardee);
4451 }
4452 } else {
4453 if (state.is_humongous()) {
4454 _g1->set_humongous_is_live(obj);
4455 }
4456 // The object is not in collection set. If we're a root scanning
4457 // closure during an initial mark pause then attempt to mark the object.
4458 if (do_mark_object == G1MarkFromRoot) {
4459 mark_object(obj);
4460 }
4461 }
4462 }
4463
4464 class G1ParEvacuateFollowersClosure : public VoidClosure {
4465 private:
4466 double _start_term;
4467 double _term_time;
4468 size_t _term_attempts;
4469
4470 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4471 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4472 protected:
4473 G1CollectedHeap* _g1h;
4474 G1ParScanThreadState* _par_scan_state;
4475 RefToScanQueueSet* _queues;
4476 ParallelTaskTerminator* _terminator;
4477
4478 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4479 RefToScanQueueSet* queues() { return _queues; }
4480 ParallelTaskTerminator* terminator() { return _terminator; }
4481
4482 public:
4483 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4484 G1ParScanThreadState* par_scan_state,
4485 RefToScanQueueSet* queues,
4486 ParallelTaskTerminator* terminator)
4487 : _g1h(g1h), _par_scan_state(par_scan_state),
4488 _queues(queues), _terminator(terminator),
4489 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4490
4491 void do_void();
4492
4493 double term_time() const { return _term_time; }
4494 size_t term_attempts() const { return _term_attempts; }
4495
4496 private:
4497 inline bool offer_termination();
4498 };
4499
4500 bool G1ParEvacuateFollowersClosure::offer_termination() {
4501 G1ParScanThreadState* const pss = par_scan_state();
4502 start_term_time();
4503 const bool res = terminator()->offer_termination();
4504 end_term_time();
4505 return res;
4506 }
4507
4508 void G1ParEvacuateFollowersClosure::do_void() {
4509 G1ParScanThreadState* const pss = par_scan_state();
4510 pss->trim_queue();
4511 do {
4512 pss->steal_and_trim_queue(queues());
4513 } while (!offer_termination());
4514 }
4515
4516 class G1KlassScanClosure : public KlassClosure {
4517 G1ParCopyHelper* _closure;
4518 bool _process_only_dirty;
4519 int _count;
4520 public:
4521 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4522 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4523 void do_klass(Klass* klass) {
4524 // If the klass has not been dirtied we know that there's
4525 // no references into the young gen and we can skip it.
4526 if (!_process_only_dirty || klass->has_modified_oops()) {
4527 // Clean the klass since we're going to scavenge all the metadata.
4528 klass->clear_modified_oops();
4529
4530 // Tell the closure that this klass is the Klass to scavenge
4531 // and is the one to dirty if oops are left pointing into the young gen.
4532 _closure->set_scanned_klass(klass);
4533
4534 klass->oops_do(_closure);
4535
4536 _closure->set_scanned_klass(NULL);
4537 }
4538 _count++;
4539 }
4540 };
4541
4542 class G1ParTask : public AbstractGangTask {
4543 protected:
4544 G1CollectedHeap* _g1h;
4545 G1ParScanThreadState** _pss;
4546 RefToScanQueueSet* _queues;
4547 G1RootProcessor* _root_processor;
4548 ParallelTaskTerminator _terminator;
4549 uint _n_workers;
4550
4551 public:
4552 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadState** per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4553 : AbstractGangTask("G1 collection"),
4554 _g1h(g1h),
4555 _pss(per_thread_states),
4556 _queues(task_queues),
4557 _root_processor(root_processor),
4558 _terminator(n_workers, _queues),
4559 _n_workers(n_workers)
4560 {}
4561
4562 RefToScanQueueSet* queues() { return _queues; }
4563
4564 RefToScanQueue *work_queue(int i) {
4565 return queues()->queue(i);
4566 }
4567
4568 ParallelTaskTerminator* terminator() { return &_terminator; }
4569
4570 // Helps out with CLD processing.
4571 //
4572 // During InitialMark we need to:
4573 // 1) Scavenge all CLDs for the young GC.
4574 // 2) Mark all objects directly reachable from strong CLDs.
4575 template <G1Mark do_mark_object>
4576 class G1CLDClosure : public CLDClosure {
4577 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4578 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4579 G1KlassScanClosure _klass_in_cld_closure;
4580 bool _claim;
4581
4582 public:
4583 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4584 bool only_young, bool claim)
4585 : _oop_closure(oop_closure),
4586 _oop_in_klass_closure(oop_closure->g1(),
4587 oop_closure->pss()),
4588 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4589 _claim(claim) {
4590
4591 }
4592
4593 void do_cld(ClassLoaderData* cld) {
4594 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4595 }
4596 };
4597
4598 void work(uint worker_id) {
4599 if (worker_id >= _n_workers) return; // no work needed this round
4600
4601 double start_sec = os::elapsedTime();
4602 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4603
4604 {
4605 ResourceMark rm;
4606 HandleMark hm;
4607
4608 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4609
4610 G1ParScanThreadState* pss = _pss[worker_id];
4611 pss->set_ref_processor(rp);
4612
4613 bool only_young = _g1h->collector_state()->gcs_are_young();
4614
4615 // Non-IM young GC.
4616 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss);
4617 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4618 only_young, // Only process dirty klasses.
4619 false); // No need to claim CLDs.
4620 // IM young GC.
4621 // Strong roots closures.
4622 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss);
4623 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4624 false, // Process all klasses.
4625 true); // Need to claim CLDs.
4626 // Weak roots closures.
4627 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4628 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4629 false, // Process all klasses.
4630 true); // Need to claim CLDs.
4631
4632 OopClosure* strong_root_cl;
4633 OopClosure* weak_root_cl;
4634 CLDClosure* strong_cld_cl;
4635 CLDClosure* weak_cld_cl;
4636
4637 bool trace_metadata = false;
4638
4639 if (_g1h->collector_state()->during_initial_mark_pause()) {
4640 // We also need to mark copied objects.
4641 strong_root_cl = &scan_mark_root_cl;
4642 strong_cld_cl = &scan_mark_cld_cl;
4643 if (ClassUnloadingWithConcurrentMark) {
4644 weak_root_cl = &scan_mark_weak_root_cl;
4645 weak_cld_cl = &scan_mark_weak_cld_cl;
4646 trace_metadata = true;
4647 } else {
4648 weak_root_cl = &scan_mark_root_cl;
4649 weak_cld_cl = &scan_mark_cld_cl;
4650 }
4651 } else {
4652 strong_root_cl = &scan_only_root_cl;
4653 weak_root_cl = &scan_only_root_cl;
4654 strong_cld_cl = &scan_only_cld_cl;
4655 weak_cld_cl = &scan_only_cld_cl;
4656 }
4657
4658 double start_strong_roots_sec = os::elapsedTime();
4659 _root_processor->evacuate_roots(strong_root_cl,
4660 weak_root_cl,
4661 strong_cld_cl,
4662 weak_cld_cl,
4663 trace_metadata,
4664 worker_id);
4665
4666 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4667 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4668 weak_root_cl,
4669 worker_id);
4670 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4671
4672 double term_sec = 0.0;
4673 size_t evac_term_attempts = 0;
4674 {
4675 double start = os::elapsedTime();
4676 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4677 evac.do_void();
4678
4679 evac_term_attempts = evac.term_attempts();
4680 term_sec = evac.term_time();
4681 double elapsed_sec = os::elapsedTime() - start;
4682 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4683 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4684 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4685 }
4686
4687 assert(pss->queue_is_empty(), "should be empty");
4688
4689 if (PrintTerminationStats) {
4690 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4691 size_t lab_waste;
4692 size_t lab_undo_waste;
4693 pss->waste(lab_waste, lab_undo_waste);
4694 _g1h->print_termination_stats(gclog_or_tty,
4695 worker_id,
4696 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4697 strong_roots_sec * 1000.0, /* strong roots time */
4698 term_sec * 1000.0, /* evac term time */
4699 evac_term_attempts, /* evac term attempts */
4700 lab_waste, /* alloc buffer waste */
4701 lab_undo_waste /* undo waste */
4702 );
4703 }
4704
4705 // Close the inner scope so that the ResourceMark and HandleMark
4706 // destructors are executed here and are included as part of the
4707 // "GC Worker Time".
4708 }
4709 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4710 }
4711 };
4712
4713 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4714 st->print_raw_cr("GC Termination Stats");
4715 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4716 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4717 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4718 }
4719
4720 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4721 uint worker_id,
4722 double elapsed_ms,
4723 double strong_roots_ms,
4724 double term_ms,
4725 size_t term_attempts,
4726 size_t alloc_buffer_waste,
4727 size_t undo_waste) const {
4728 st->print_cr("%3d %9.2f %9.2f %6.2f "
4729 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4730 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4731 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4732 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4733 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4734 alloc_buffer_waste * HeapWordSize / K,
4735 undo_waste * HeapWordSize / K);
4736 }
4737
4738 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4739 private:
4740 BoolObjectClosure* _is_alive;
4741 int _initial_string_table_size;
4742 int _initial_symbol_table_size;
4743
4744 bool _process_strings;
4745 int _strings_processed;
4746 int _strings_removed;
4747
4748 bool _process_symbols;
4749 int _symbols_processed;
4750 int _symbols_removed;
4751
4752 public:
4753 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4754 AbstractGangTask("String/Symbol Unlinking"),
4755 _is_alive(is_alive),
4756 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4757 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4758
4759 _initial_string_table_size = StringTable::the_table()->table_size();
4760 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4761 if (process_strings) {
4762 StringTable::clear_parallel_claimed_index();
4763 }
4764 if (process_symbols) {
4765 SymbolTable::clear_parallel_claimed_index();
4766 }
4767 }
4768
4769 ~G1StringSymbolTableUnlinkTask() {
4770 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4771 err_msg("claim value %d after unlink less than initial string table size %d",
4772 StringTable::parallel_claimed_index(), _initial_string_table_size));
4773 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4774 err_msg("claim value %d after unlink less than initial symbol table size %d",
4775 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4776
4777 if (G1TraceStringSymbolTableScrubbing) {
4778 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4779 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4780 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4781 strings_processed(), strings_removed(),
4782 symbols_processed(), symbols_removed());
4783 }
4784 }
4785
4786 void work(uint worker_id) {
4787 int strings_processed = 0;
4788 int strings_removed = 0;
4789 int symbols_processed = 0;
4790 int symbols_removed = 0;
4791 if (_process_strings) {
4792 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4793 Atomic::add(strings_processed, &_strings_processed);
4794 Atomic::add(strings_removed, &_strings_removed);
4795 }
4796 if (_process_symbols) {
4797 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4798 Atomic::add(symbols_processed, &_symbols_processed);
4799 Atomic::add(symbols_removed, &_symbols_removed);
4800 }
4801 }
4802
4803 size_t strings_processed() const { return (size_t)_strings_processed; }
4804 size_t strings_removed() const { return (size_t)_strings_removed; }
4805
4806 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4807 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4808 };
4809
4810 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4811 private:
4812 static Monitor* _lock;
4813
4814 BoolObjectClosure* const _is_alive;
4815 const bool _unloading_occurred;
4816 const uint _num_workers;
4817
4818 // Variables used to claim nmethods.
4819 nmethod* _first_nmethod;
4820 volatile nmethod* _claimed_nmethod;
4821
4822 // The list of nmethods that need to be processed by the second pass.
4823 volatile nmethod* _postponed_list;
4824 volatile uint _num_entered_barrier;
4825
4826 public:
4827 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4828 _is_alive(is_alive),
4829 _unloading_occurred(unloading_occurred),
4830 _num_workers(num_workers),
4831 _first_nmethod(NULL),
4832 _claimed_nmethod(NULL),
4833 _postponed_list(NULL),
4834 _num_entered_barrier(0)
4835 {
4836 nmethod::increase_unloading_clock();
4837 // Get first alive nmethod
4838 NMethodIterator iter = NMethodIterator();
4839 if(iter.next_alive()) {
4840 _first_nmethod = iter.method();
4841 }
4842 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4843 }
4844
4845 ~G1CodeCacheUnloadingTask() {
4846 CodeCache::verify_clean_inline_caches();
4847
4848 CodeCache::set_needs_cache_clean(false);
4849 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4850
4851 CodeCache::verify_icholder_relocations();
4852 }
4853
4854 private:
4855 void add_to_postponed_list(nmethod* nm) {
4856 nmethod* old;
4857 do {
4858 old = (nmethod*)_postponed_list;
4859 nm->set_unloading_next(old);
4860 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4861 }
4862
4863 void clean_nmethod(nmethod* nm) {
4864 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4865
4866 if (postponed) {
4867 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4868 add_to_postponed_list(nm);
4869 }
4870
4871 // Mark that this thread has been cleaned/unloaded.
4872 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4873 nm->set_unloading_clock(nmethod::global_unloading_clock());
4874 }
4875
4876 void clean_nmethod_postponed(nmethod* nm) {
4877 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4878 }
4879
4880 static const int MaxClaimNmethods = 16;
4881
4882 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4883 nmethod* first;
4884 NMethodIterator last;
4885
4886 do {
4887 *num_claimed_nmethods = 0;
4888
4889 first = (nmethod*)_claimed_nmethod;
4890 last = NMethodIterator(first);
4891
4892 if (first != NULL) {
4893
4894 for (int i = 0; i < MaxClaimNmethods; i++) {
4895 if (!last.next_alive()) {
4896 break;
4897 }
4898 claimed_nmethods[i] = last.method();
4899 (*num_claimed_nmethods)++;
4900 }
4901 }
4902
4903 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4904 }
4905
4906 nmethod* claim_postponed_nmethod() {
4907 nmethod* claim;
4908 nmethod* next;
4909
4910 do {
4911 claim = (nmethod*)_postponed_list;
4912 if (claim == NULL) {
4913 return NULL;
4914 }
4915
4916 next = claim->unloading_next();
4917
4918 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4919
4920 return claim;
4921 }
4922
4923 public:
4924 // Mark that we're done with the first pass of nmethod cleaning.
4925 void barrier_mark(uint worker_id) {
4926 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4927 _num_entered_barrier++;
4928 if (_num_entered_barrier == _num_workers) {
4929 ml.notify_all();
4930 }
4931 }
4932
4933 // See if we have to wait for the other workers to
4934 // finish their first-pass nmethod cleaning work.
4935 void barrier_wait(uint worker_id) {
4936 if (_num_entered_barrier < _num_workers) {
4937 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4938 while (_num_entered_barrier < _num_workers) {
4939 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4940 }
4941 }
4942 }
4943
4944 // Cleaning and unloading of nmethods. Some work has to be postponed
4945 // to the second pass, when we know which nmethods survive.
4946 void work_first_pass(uint worker_id) {
4947 // The first nmethods is claimed by the first worker.
4948 if (worker_id == 0 && _first_nmethod != NULL) {
4949 clean_nmethod(_first_nmethod);
4950 _first_nmethod = NULL;
4951 }
4952
4953 int num_claimed_nmethods;
4954 nmethod* claimed_nmethods[MaxClaimNmethods];
4955
4956 while (true) {
4957 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4958
4959 if (num_claimed_nmethods == 0) {
4960 break;
4961 }
4962
4963 for (int i = 0; i < num_claimed_nmethods; i++) {
4964 clean_nmethod(claimed_nmethods[i]);
4965 }
4966 }
4967 }
4968
4969 void work_second_pass(uint worker_id) {
4970 nmethod* nm;
4971 // Take care of postponed nmethods.
4972 while ((nm = claim_postponed_nmethod()) != NULL) {
4973 clean_nmethod_postponed(nm);
4974 }
4975 }
4976 };
4977
4978 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4979
4980 class G1KlassCleaningTask : public StackObj {
4981 BoolObjectClosure* _is_alive;
4982 volatile jint _clean_klass_tree_claimed;
4983 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4984
4985 public:
4986 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4987 _is_alive(is_alive),
4988 _clean_klass_tree_claimed(0),
4989 _klass_iterator() {
4990 }
4991
4992 private:
4993 bool claim_clean_klass_tree_task() {
4994 if (_clean_klass_tree_claimed) {
4995 return false;
4996 }
4997
4998 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4999 }
5000
5001 InstanceKlass* claim_next_klass() {
5002 Klass* klass;
5003 do {
5004 klass =_klass_iterator.next_klass();
5005 } while (klass != NULL && !klass->oop_is_instance());
5006
5007 return (InstanceKlass*)klass;
5008 }
5009
5010 public:
5011
5012 void clean_klass(InstanceKlass* ik) {
5013 ik->clean_implementors_list(_is_alive);
5014 ik->clean_method_data(_is_alive);
5015
5016 // G1 specific cleanup work that has
5017 // been moved here to be done in parallel.
5018 ik->clean_dependent_nmethods();
5019 }
5020
5021 void work() {
5022 ResourceMark rm;
5023
5024 // One worker will clean the subklass/sibling klass tree.
5025 if (claim_clean_klass_tree_task()) {
5026 Klass::clean_subklass_tree(_is_alive);
5027 }
5028
5029 // All workers will help cleaning the classes,
5030 InstanceKlass* klass;
5031 while ((klass = claim_next_klass()) != NULL) {
5032 clean_klass(klass);
5033 }
5034 }
5035 };
5036
5037 // To minimize the remark pause times, the tasks below are done in parallel.
5038 class G1ParallelCleaningTask : public AbstractGangTask {
5039 private:
5040 G1StringSymbolTableUnlinkTask _string_symbol_task;
5041 G1CodeCacheUnloadingTask _code_cache_task;
5042 G1KlassCleaningTask _klass_cleaning_task;
5043
5044 public:
5045 // The constructor is run in the VMThread.
5046 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5047 AbstractGangTask("Parallel Cleaning"),
5048 _string_symbol_task(is_alive, process_strings, process_symbols),
5049 _code_cache_task(num_workers, is_alive, unloading_occurred),
5050 _klass_cleaning_task(is_alive) {
5051 }
5052
5053 // The parallel work done by all worker threads.
5054 void work(uint worker_id) {
5055 // Do first pass of code cache cleaning.
5056 _code_cache_task.work_first_pass(worker_id);
5057
5058 // Let the threads mark that the first pass is done.
5059 _code_cache_task.barrier_mark(worker_id);
5060
5061 // Clean the Strings and Symbols.
5062 _string_symbol_task.work(worker_id);
5063
5064 // Wait for all workers to finish the first code cache cleaning pass.
5065 _code_cache_task.barrier_wait(worker_id);
5066
5067 // Do the second code cache cleaning work, which realize on
5068 // the liveness information gathered during the first pass.
5069 _code_cache_task.work_second_pass(worker_id);
5070
5071 // Clean all klasses that were not unloaded.
5072 _klass_cleaning_task.work();
5073 }
5074 };
5075
5076
5077 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5078 bool process_strings,
5079 bool process_symbols,
5080 bool class_unloading_occurred) {
5081 uint n_workers = workers()->active_workers();
5082
5083 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5084 n_workers, class_unloading_occurred);
5085 workers()->run_task(&g1_unlink_task);
5086 }
5087
5088 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5089 bool process_strings, bool process_symbols) {
5090 {
5091 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5092 workers()->run_task(&g1_unlink_task);
5093 }
5094
5095 if (G1StringDedup::is_enabled()) {
5096 G1StringDedup::unlink(is_alive);
5097 }
5098 }
5099
5100 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5101 private:
5102 DirtyCardQueueSet* _queue;
5103 public:
5104 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5105
5106 virtual void work(uint worker_id) {
5107 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5108 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5109
5110 RedirtyLoggedCardTableEntryClosure cl;
5111 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5112
5113 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5114 }
5115 };
5116
5117 void G1CollectedHeap::redirty_logged_cards() {
5118 double redirty_logged_cards_start = os::elapsedTime();
5119
5120 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5121 dirty_card_queue_set().reset_for_par_iteration();
5122 workers()->run_task(&redirty_task);
5123
5124 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5125 dcq.merge_bufferlists(&dirty_card_queue_set());
5126 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5127
5128 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5129 }
5130
5131 // Weak Reference Processing support
5132
5133 // An always "is_alive" closure that is used to preserve referents.
5134 // If the object is non-null then it's alive. Used in the preservation
5135 // of referent objects that are pointed to by reference objects
5136 // discovered by the CM ref processor.
5137 class G1AlwaysAliveClosure: public BoolObjectClosure {
5138 G1CollectedHeap* _g1;
5139 public:
5140 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5141 bool do_object_b(oop p) {
5142 if (p != NULL) {
5143 return true;
5144 }
5145 return false;
5146 }
5147 };
5148
5149 bool G1STWIsAliveClosure::do_object_b(oop p) {
5150 // An object is reachable if it is outside the collection set,
5151 // or is inside and copied.
5152 return !_g1->is_in_cset(p) || p->is_forwarded();
5153 }
5154
5155 // Non Copying Keep Alive closure
5156 class G1KeepAliveClosure: public OopClosure {
5157 G1CollectedHeap* _g1;
5158 public:
5159 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5160 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5161 void do_oop(oop* p) {
5162 oop obj = *p;
5163 assert(obj != NULL, "the caller should have filtered out NULL values");
5164
5165 const InCSetState cset_state = _g1->in_cset_state(obj);
5166 if (!cset_state.is_in_cset_or_humongous()) {
5167 return;
5168 }
5169 if (cset_state.is_in_cset()) {
5170 assert( obj->is_forwarded(), "invariant" );
5171 *p = obj->forwardee();
5172 } else {
5173 assert(!obj->is_forwarded(), "invariant" );
5174 assert(cset_state.is_humongous(),
5175 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5176 _g1->set_humongous_is_live(obj);
5177 }
5178 }
5179 };
5180
5181 // Copying Keep Alive closure - can be called from both
5182 // serial and parallel code as long as different worker
5183 // threads utilize different G1ParScanThreadState instances
5184 // and different queues.
5185
5186 class G1CopyingKeepAliveClosure: public OopClosure {
5187 G1CollectedHeap* _g1h;
5188 OopClosure* _copy_non_heap_obj_cl;
5189 G1ParScanThreadState* _par_scan_state;
5190
5191 public:
5192 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5193 OopClosure* non_heap_obj_cl,
5194 G1ParScanThreadState* pss):
5195 _g1h(g1h),
5196 _copy_non_heap_obj_cl(non_heap_obj_cl),
5197 _par_scan_state(pss)
5198 {}
5199
5200 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5201 virtual void do_oop( oop* p) { do_oop_work(p); }
5202
5203 template <class T> void do_oop_work(T* p) {
5204 oop obj = oopDesc::load_decode_heap_oop(p);
5205
5206 if (_g1h->is_in_cset_or_humongous(obj)) {
5207 // If the referent object has been forwarded (either copied
5208 // to a new location or to itself in the event of an
5209 // evacuation failure) then we need to update the reference
5210 // field and, if both reference and referent are in the G1
5211 // heap, update the RSet for the referent.
5212 //
5213 // If the referent has not been forwarded then we have to keep
5214 // it alive by policy. Therefore we have copy the referent.
5215 //
5216 // If the reference field is in the G1 heap then we can push
5217 // on the PSS queue. When the queue is drained (after each
5218 // phase of reference processing) the object and it's followers
5219 // will be copied, the reference field set to point to the
5220 // new location, and the RSet updated. Otherwise we need to
5221 // use the the non-heap or metadata closures directly to copy
5222 // the referent object and update the pointer, while avoiding
5223 // updating the RSet.
5224
5225 if (_g1h->is_in_g1_reserved(p)) {
5226 _par_scan_state->push_on_queue(p);
5227 } else {
5228 assert(!Metaspace::contains((const void*)p),
5229 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5230 _copy_non_heap_obj_cl->do_oop(p);
5231 }
5232 }
5233 }
5234 };
5235
5236 // Serial drain queue closure. Called as the 'complete_gc'
5237 // closure for each discovered list in some of the
5238 // reference processing phases.
5239
5240 class G1STWDrainQueueClosure: public VoidClosure {
5241 protected:
5242 G1CollectedHeap* _g1h;
5243 G1ParScanThreadState* _par_scan_state;
5244
5245 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5246
5247 public:
5248 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5249 _g1h(g1h),
5250 _par_scan_state(pss)
5251 { }
5252
5253 void do_void() {
5254 G1ParScanThreadState* const pss = par_scan_state();
5255 pss->trim_queue();
5256 }
5257 };
5258
5259 // Parallel Reference Processing closures
5260
5261 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5262 // processing during G1 evacuation pauses.
5263
5264 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5265 private:
5266 G1CollectedHeap* _g1h;
5267 G1ParScanThreadState** _pss;
5268 RefToScanQueueSet* _queues;
5269 WorkGang* _workers;
5270 uint _active_workers;
5271
5272 public:
5273 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5274 G1ParScanThreadState** per_thread_states,
5275 WorkGang* workers,
5276 RefToScanQueueSet *task_queues,
5277 uint n_workers) :
5278 _g1h(g1h),
5279 _pss(per_thread_states),
5280 _queues(task_queues),
5281 _workers(workers),
5282 _active_workers(n_workers)
5283 {
5284 assert(n_workers > 0, "shouldn't call this otherwise");
5285 }
5286
5287 // Executes the given task using concurrent marking worker threads.
5288 virtual void execute(ProcessTask& task);
5289 virtual void execute(EnqueueTask& task);
5290 };
5291
5292 // Gang task for possibly parallel reference processing
5293
5294 class G1STWRefProcTaskProxy: public AbstractGangTask {
5295 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5296 ProcessTask& _proc_task;
5297 G1CollectedHeap* _g1h;
5298 G1ParScanThreadState** _pss;
5299 RefToScanQueueSet* _task_queues;
5300 ParallelTaskTerminator* _terminator;
5301
5302 public:
5303 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5304 G1CollectedHeap* g1h,
5305 G1ParScanThreadState** per_thread_states,
5306 RefToScanQueueSet *task_queues,
5307 ParallelTaskTerminator* terminator) :
5308 AbstractGangTask("Process reference objects in parallel"),
5309 _proc_task(proc_task),
5310 _g1h(g1h),
5311 _pss(per_thread_states),
5312 _task_queues(task_queues),
5313 _terminator(terminator)
5314 {}
5315
5316 virtual void work(uint worker_id) {
5317 // The reference processing task executed by a single worker.
5318 ResourceMark rm;
5319 HandleMark hm;
5320
5321 G1STWIsAliveClosure is_alive(_g1h);
5322
5323 G1ParScanThreadState* pss = _pss[worker_id];
5324 pss->set_ref_processor(NULL);
5325
5326 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5327
5328 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5329
5330 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5331
5332 if (_g1h->collector_state()->during_initial_mark_pause()) {
5333 // We also need to mark copied objects.
5334 copy_non_heap_cl = ©_mark_non_heap_cl;
5335 }
5336
5337 // Keep alive closure.
5338 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5339
5340 // Complete GC closure
5341 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5342
5343 // Call the reference processing task's work routine.
5344 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5345
5346 // Note we cannot assert that the refs array is empty here as not all
5347 // of the processing tasks (specifically phase2 - pp2_work) execute
5348 // the complete_gc closure (which ordinarily would drain the queue) so
5349 // the queue may not be empty.
5350 }
5351 };
5352
5353 // Driver routine for parallel reference processing.
5354 // Creates an instance of the ref processing gang
5355 // task and has the worker threads execute it.
5356 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5357 assert(_workers != NULL, "Need parallel worker threads.");
5358
5359 ParallelTaskTerminator terminator(_active_workers, _queues);
5360 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5361
5362 _workers->run_task(&proc_task_proxy);
5363 }
5364
5365 // Gang task for parallel reference enqueueing.
5366
5367 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5368 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5369 EnqueueTask& _enq_task;
5370
5371 public:
5372 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5373 AbstractGangTask("Enqueue reference objects in parallel"),
5374 _enq_task(enq_task)
5375 { }
5376
5377 virtual void work(uint worker_id) {
5378 _enq_task.work(worker_id);
5379 }
5380 };
5381
5382 // Driver routine for parallel reference enqueueing.
5383 // Creates an instance of the ref enqueueing gang
5384 // task and has the worker threads execute it.
5385
5386 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5387 assert(_workers != NULL, "Need parallel worker threads.");
5388
5389 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5390
5391 _workers->run_task(&enq_task_proxy);
5392 }
5393
5394 // End of weak reference support closures
5395
5396 // Abstract task used to preserve (i.e. copy) any referent objects
5397 // that are in the collection set and are pointed to by reference
5398 // objects discovered by the CM ref processor.
5399
5400 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5401 protected:
5402 G1CollectedHeap* _g1h;
5403 G1ParScanThreadState** _pss;
5404 RefToScanQueueSet* _queues;
5405 ParallelTaskTerminator _terminator;
5406 uint _n_workers;
5407
5408 public:
5409 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadState** per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5410 AbstractGangTask("ParPreserveCMReferents"),
5411 _g1h(g1h),
5412 _pss(per_thread_states),
5413 _queues(task_queues),
5414 _terminator(workers, _queues),
5415 _n_workers(workers)
5416 { }
5417
5418 void work(uint worker_id) {
5419 ResourceMark rm;
5420 HandleMark hm;
5421
5422 G1ParScanThreadState* pss = _pss[worker_id];
5423 pss->set_ref_processor(NULL);
5424 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5425
5426 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5427
5428 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5429
5430 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5431
5432 if (_g1h->collector_state()->during_initial_mark_pause()) {
5433 // We also need to mark copied objects.
5434 copy_non_heap_cl = ©_mark_non_heap_cl;
5435 }
5436
5437 // Is alive closure
5438 G1AlwaysAliveClosure always_alive(_g1h);
5439
5440 // Copying keep alive closure. Applied to referent objects that need
5441 // to be copied.
5442 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5443
5444 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5445
5446 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5447 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5448
5449 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5450 // So this must be true - but assert just in case someone decides to
5451 // change the worker ids.
5452 assert(worker_id < limit, "sanity");
5453 assert(!rp->discovery_is_atomic(), "check this code");
5454
5455 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5456 for (uint idx = worker_id; idx < limit; idx += stride) {
5457 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5458
5459 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5460 while (iter.has_next()) {
5461 // Since discovery is not atomic for the CM ref processor, we
5462 // can see some null referent objects.
5463 iter.load_ptrs(DEBUG_ONLY(true));
5464 oop ref = iter.obj();
5465
5466 // This will filter nulls.
5467 if (iter.is_referent_alive()) {
5468 iter.make_referent_alive();
5469 }
5470 iter.move_to_next();
5471 }
5472 }
5473
5474 // Drain the queue - which may cause stealing
5475 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5476 drain_queue.do_void();
5477 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5478 assert(pss->queue_is_empty(), "should be");
5479 }
5480 };
5481
5482 // Weak Reference processing during an evacuation pause (part 1).
5483 void G1CollectedHeap::process_discovered_references(G1ParScanThreadState** per_thread_states) {
5484 double ref_proc_start = os::elapsedTime();
5485
5486 ReferenceProcessor* rp = _ref_processor_stw;
5487 assert(rp->discovery_enabled(), "should have been enabled");
5488
5489 // Any reference objects, in the collection set, that were 'discovered'
5490 // by the CM ref processor should have already been copied (either by
5491 // applying the external root copy closure to the discovered lists, or
5492 // by following an RSet entry).
5493 //
5494 // But some of the referents, that are in the collection set, that these
5495 // reference objects point to may not have been copied: the STW ref
5496 // processor would have seen that the reference object had already
5497 // been 'discovered' and would have skipped discovering the reference,
5498 // but would not have treated the reference object as a regular oop.
5499 // As a result the copy closure would not have been applied to the
5500 // referent object.
5501 //
5502 // We need to explicitly copy these referent objects - the references
5503 // will be processed at the end of remarking.
5504 //
5505 // We also need to do this copying before we process the reference
5506 // objects discovered by the STW ref processor in case one of these
5507 // referents points to another object which is also referenced by an
5508 // object discovered by the STW ref processor.
5509
5510 uint no_of_gc_workers = workers()->active_workers();
5511
5512 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5513 per_thread_states,
5514 no_of_gc_workers,
5515 _task_queues);
5516
5517 workers()->run_task(&keep_cm_referents);
5518
5519 // Closure to test whether a referent is alive.
5520 G1STWIsAliveClosure is_alive(this);
5521
5522 // Even when parallel reference processing is enabled, the processing
5523 // of JNI refs is serial and performed serially by the current thread
5524 // rather than by a worker. The following PSS will be used for processing
5525 // JNI refs.
5526
5527 // Use only a single queue for this PSS.
5528 G1ParScanThreadState* pss = per_thread_states[0];
5529 pss->set_ref_processor(NULL);
5530 assert(pss->queue_is_empty(), "pre-condition");
5531
5532 // We do not embed a reference processor in the copying/scanning
5533 // closures while we're actually processing the discovered
5534 // reference objects.
5535
5536 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss);
5537
5538 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5539
5540 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5541
5542 if (collector_state()->during_initial_mark_pause()) {
5543 // We also need to mark copied objects.
5544 copy_non_heap_cl = ©_mark_non_heap_cl;
5545 }
5546
5547 // Keep alive closure.
5548 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5549
5550 // Serial Complete GC closure
5551 G1STWDrainQueueClosure drain_queue(this, pss);
5552
5553 // Setup the soft refs policy...
5554 rp->setup_policy(false);
5555
5556 ReferenceProcessorStats stats;
5557 if (!rp->processing_is_mt()) {
5558 // Serial reference processing...
5559 stats = rp->process_discovered_references(&is_alive,
5560 &keep_alive,
5561 &drain_queue,
5562 NULL,
5563 _gc_timer_stw,
5564 _gc_tracer_stw->gc_id());
5565 } else {
5566 // Parallel reference processing
5567 assert(rp->num_q() == no_of_gc_workers, "sanity");
5568 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5569
5570 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5571 stats = rp->process_discovered_references(&is_alive,
5572 &keep_alive,
5573 &drain_queue,
5574 &par_task_executor,
5575 _gc_timer_stw,
5576 _gc_tracer_stw->gc_id());
5577 }
5578
5579 _gc_tracer_stw->report_gc_reference_stats(stats);
5580
5581 // We have completed copying any necessary live referent objects.
5582 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5583
5584 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5585 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5586 }
5587
5588 // Weak Reference processing during an evacuation pause (part 2).
5589 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadState** per_thread_states) {
5590 double ref_enq_start = os::elapsedTime();
5591
5592 ReferenceProcessor* rp = _ref_processor_stw;
5593 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5594
5595 // Now enqueue any remaining on the discovered lists on to
5596 // the pending list.
5597 if (!rp->processing_is_mt()) {
5598 // Serial reference processing...
5599 rp->enqueue_discovered_references();
5600 } else {
5601 // Parallel reference enqueueing
5602
5603 uint n_workers = workers()->active_workers();
5604
5605 assert(rp->num_q() == n_workers, "sanity");
5606 assert(n_workers <= rp->max_num_q(), "sanity");
5607
5608 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5609 rp->enqueue_discovered_references(&par_task_executor);
5610 }
5611
5612 rp->verify_no_references_recorded();
5613 assert(!rp->discovery_enabled(), "should have been disabled");
5614
5615 // FIXME
5616 // CM's reference processing also cleans up the string and symbol tables.
5617 // Should we do that here also? We could, but it is a serial operation
5618 // and could significantly increase the pause time.
5619
5620 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5621 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5622 }
5623
5624 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5625 _expand_heap_after_alloc_failure = true;
5626 _evacuation_failed = false;
5627
5628 // Should G1EvacuationFailureALot be in effect for this GC?
5629 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5630
5631 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5632
5633 // Disable the hot card cache.
5634 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5635 hot_card_cache->reset_hot_cache_claimed_index();
5636 hot_card_cache->set_use_cache(false);
5637
5638 const uint n_workers = workers()->active_workers();
5639
5640 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5641 double start_par_time_sec = os::elapsedTime();
5642 double end_par_time_sec;
5643
5644 G1ParScanThreadState** per_thread_states = NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC);
5645 for (uint i = 0; i < n_workers; i++) {
5646 per_thread_states[i] = new_par_scan_state(i);
5647 }
5648
5649 {
5650 G1RootProcessor root_processor(this, n_workers);
5651 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5652 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5653 if (collector_state()->during_initial_mark_pause()) {
5654 ClassLoaderDataGraph::clear_claimed_marks();
5655 }
5656
5657 // The individual threads will set their evac-failure closures.
5658 if (PrintTerminationStats) {
5659 print_termination_stats_hdr(gclog_or_tty);
5660 }
5661
5662 workers()->run_task(&g1_par_task);
5663 end_par_time_sec = os::elapsedTime();
5664
5665 // Closing the inner scope will execute the destructor
5666 // for the G1RootProcessor object. We record the current
5667 // elapsed time before closing the scope so that time
5668 // taken for the destructor is NOT included in the
5669 // reported parallel time.
5670 }
5671
5672 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5673
5674 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5675 phase_times->record_par_time(par_time_ms);
5676
5677 double code_root_fixup_time_ms =
5678 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5679 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5680
5681 // Process any discovered reference objects - we have
5682 // to do this _before_ we retire the GC alloc regions
5683 // as we may have to copy some 'reachable' referent
5684 // objects (and their reachable sub-graphs) that were
5685 // not copied during the pause.
5686 process_discovered_references(per_thread_states);
5687
5688 if (G1StringDedup::is_enabled()) {
5689 double fixup_start = os::elapsedTime();
5690
5691 G1STWIsAliveClosure is_alive(this);
5692 G1KeepAliveClosure keep_alive(this);
5693 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5694
5695 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5696 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5697 }
5698
5699 _allocator->release_gc_alloc_regions(evacuation_info);
5700 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5701
5702 for (uint i = 0; i < n_workers; i++) {
5703 G1ParScanThreadState* pss = per_thread_states[i];
5704 delete pss;
5705 }
5706 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, per_thread_states);
5707
5708 record_obj_copy_mem_stats();
5709
5710 // Reset and re-enable the hot card cache.
5711 // Note the counts for the cards in the regions in the
5712 // collection set are reset when the collection set is freed.
5713 hot_card_cache->reset_hot_cache();
5714 hot_card_cache->set_use_cache(true);
5715
5716 purge_code_root_memory();
5717
5718 if (evacuation_failed()) {
5719 remove_self_forwarding_pointers();
5720
5721 // Reset the G1EvacuationFailureALot counters and flags
5722 // Note: the values are reset only when an actual
5723 // evacuation failure occurs.
5724 NOT_PRODUCT(reset_evacuation_should_fail();)
5725 }
5726
5727 // Enqueue any remaining references remaining on the STW
5728 // reference processor's discovered lists. We need to do
5729 // this after the card table is cleaned (and verified) as
5730 // the act of enqueueing entries on to the pending list
5731 // will log these updates (and dirty their associated
5732 // cards). We need these updates logged to update any
5733 // RSets.
5734 enqueue_discovered_references(per_thread_states);
5735
5736 redirty_logged_cards();
5737 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5738 }
5739
5740 void G1CollectedHeap::record_obj_copy_mem_stats() {
5741 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5742 create_g1_evac_summary(&_old_evac_stats));
5743 }
5744
5745 void G1CollectedHeap::free_region(HeapRegion* hr,
5746 FreeRegionList* free_list,
5747 bool par,
5748 bool locked) {
5749 assert(!hr->is_free(), "the region should not be free");
5750 assert(!hr->is_empty(), "the region should not be empty");
5751 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5752 assert(free_list != NULL, "pre-condition");
5753
5754 if (G1VerifyBitmaps) {
5755 MemRegion mr(hr->bottom(), hr->end());
5756 concurrent_mark()->clearRangePrevBitmap(mr);
5757 }
5758
5759 // Clear the card counts for this region.
5760 // Note: we only need to do this if the region is not young
5761 // (since we don't refine cards in young regions).
5762 if (!hr->is_young()) {
5763 _cg1r->hot_card_cache()->reset_card_counts(hr);
5764 }
5765 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5766 free_list->add_ordered(hr);
5767 }
5768
5769 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5770 FreeRegionList* free_list,
5771 bool par) {
5772 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5773 assert(free_list != NULL, "pre-condition");
5774
5775 size_t hr_capacity = hr->capacity();
5776 // We need to read this before we make the region non-humongous,
5777 // otherwise the information will be gone.
5778 uint last_index = hr->last_hc_index();
5779 hr->clear_humongous();
5780 free_region(hr, free_list, par);
5781
5782 uint i = hr->hrm_index() + 1;
5783 while (i < last_index) {
5784 HeapRegion* curr_hr = region_at(i);
5785 assert(curr_hr->is_continues_humongous(), "invariant");
5786 curr_hr->clear_humongous();
5787 free_region(curr_hr, free_list, par);
5788 i += 1;
5789 }
5790 }
5791
5792 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5793 const HeapRegionSetCount& humongous_regions_removed) {
5794 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5795 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5796 _old_set.bulk_remove(old_regions_removed);
5797 _humongous_set.bulk_remove(humongous_regions_removed);
5798 }
5799
5800 }
5801
5802 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5803 assert(list != NULL, "list can't be null");
5804 if (!list->is_empty()) {
5805 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5806 _hrm.insert_list_into_free_list(list);
5807 }
5808 }
5809
5810 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5811 decrease_used(bytes);
5812 }
5813
5814 class G1ParCleanupCTTask : public AbstractGangTask {
5815 G1SATBCardTableModRefBS* _ct_bs;
5816 G1CollectedHeap* _g1h;
5817 HeapRegion* volatile _su_head;
5818 public:
5819 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5820 G1CollectedHeap* g1h) :
5821 AbstractGangTask("G1 Par Cleanup CT Task"),
5822 _ct_bs(ct_bs), _g1h(g1h) { }
5823
5824 void work(uint worker_id) {
5825 HeapRegion* r;
5826 while (r = _g1h->pop_dirty_cards_region()) {
5827 clear_cards(r);
5828 }
5829 }
5830
5831 void clear_cards(HeapRegion* r) {
5832 // Cards of the survivors should have already been dirtied.
5833 if (!r->is_survivor()) {
5834 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5835 }
5836 }
5837 };
5838
5839 #ifndef PRODUCT
5840 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5841 G1CollectedHeap* _g1h;
5842 G1SATBCardTableModRefBS* _ct_bs;
5843 public:
5844 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5845 : _g1h(g1h), _ct_bs(ct_bs) { }
5846 virtual bool doHeapRegion(HeapRegion* r) {
5847 if (r->is_survivor()) {
5848 _g1h->verify_dirty_region(r);
5849 } else {
5850 _g1h->verify_not_dirty_region(r);
5851 }
5852 return false;
5853 }
5854 };
5855
5856 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5857 // All of the region should be clean.
5858 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5859 MemRegion mr(hr->bottom(), hr->end());
5860 ct_bs->verify_not_dirty_region(mr);
5861 }
5862
5863 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5864 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5865 // dirty allocated blocks as they allocate them. The thread that
5866 // retires each region and replaces it with a new one will do a
5867 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5868 // not dirty that area (one less thing to have to do while holding
5869 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5870 // is dirty.
5871 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5872 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5873 if (hr->is_young()) {
5874 ct_bs->verify_g1_young_region(mr);
5875 } else {
5876 ct_bs->verify_dirty_region(mr);
5877 }
5878 }
5879
5880 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5881 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5882 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5883 verify_dirty_region(hr);
5884 }
5885 }
5886
5887 void G1CollectedHeap::verify_dirty_young_regions() {
5888 verify_dirty_young_list(_young_list->first_region());
5889 }
5890
5891 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5892 HeapWord* tams, HeapWord* end) {
5893 guarantee(tams <= end,
5894 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5895 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5896 if (result < end) {
5897 gclog_or_tty->cr();
5898 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5899 bitmap_name, p2i(result));
5900 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5901 bitmap_name, p2i(tams), p2i(end));
5902 return false;
5903 }
5904 return true;
5905 }
5906
5907 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5908 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5909 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5910
5911 HeapWord* bottom = hr->bottom();
5912 HeapWord* ptams = hr->prev_top_at_mark_start();
5913 HeapWord* ntams = hr->next_top_at_mark_start();
5914 HeapWord* end = hr->end();
5915
5916 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5917
5918 bool res_n = true;
5919 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5920 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5921 // if we happen to be in that state.
5922 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5923 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5924 }
5925 if (!res_p || !res_n) {
5926 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5927 HR_FORMAT_PARAMS(hr));
5928 gclog_or_tty->print_cr("#### Caller: %s", caller);
5929 return false;
5930 }
5931 return true;
5932 }
5933
5934 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5935 if (!G1VerifyBitmaps) return;
5936
5937 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5938 }
5939
5940 class G1VerifyBitmapClosure : public HeapRegionClosure {
5941 private:
5942 const char* _caller;
5943 G1CollectedHeap* _g1h;
5944 bool _failures;
5945
5946 public:
5947 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5948 _caller(caller), _g1h(g1h), _failures(false) { }
5949
5950 bool failures() { return _failures; }
5951
5952 virtual bool doHeapRegion(HeapRegion* hr) {
5953 if (hr->is_continues_humongous()) return false;
5954
5955 bool result = _g1h->verify_bitmaps(_caller, hr);
5956 if (!result) {
5957 _failures = true;
5958 }
5959 return false;
5960 }
5961 };
5962
5963 void G1CollectedHeap::check_bitmaps(const char* caller) {
5964 if (!G1VerifyBitmaps) return;
5965
5966 G1VerifyBitmapClosure cl(caller, this);
5967 heap_region_iterate(&cl);
5968 guarantee(!cl.failures(), "bitmap verification");
5969 }
5970
5971 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5972 private:
5973 bool _failures;
5974 public:
5975 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5976
5977 virtual bool doHeapRegion(HeapRegion* hr) {
5978 uint i = hr->hrm_index();
5979 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5980 if (hr->is_humongous()) {
5981 if (hr->in_collection_set()) {
5982 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5983 _failures = true;
5984 return true;
5985 }
5986 if (cset_state.is_in_cset()) {
5987 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5988 _failures = true;
5989 return true;
5990 }
5991 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5992 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5993 _failures = true;
5994 return true;
5995 }
5996 } else {
5997 if (cset_state.is_humongous()) {
5998 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5999 _failures = true;
6000 return true;
6001 }
6002 if (hr->in_collection_set() != cset_state.is_in_cset()) {
6003 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6004 hr->in_collection_set(), cset_state.value(), i);
6005 _failures = true;
6006 return true;
6007 }
6008 if (cset_state.is_in_cset()) {
6009 if (hr->is_young() != (cset_state.is_young())) {
6010 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6011 hr->is_young(), cset_state.value(), i);
6012 _failures = true;
6013 return true;
6014 }
6015 if (hr->is_old() != (cset_state.is_old())) {
6016 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6017 hr->is_old(), cset_state.value(), i);
6018 _failures = true;
6019 return true;
6020 }
6021 }
6022 }
6023 return false;
6024 }
6025
6026 bool failures() const { return _failures; }
6027 };
6028
6029 bool G1CollectedHeap::check_cset_fast_test() {
6030 G1CheckCSetFastTableClosure cl;
6031 _hrm.iterate(&cl);
6032 return !cl.failures();
6033 }
6034 #endif // PRODUCT
6035
6036 void G1CollectedHeap::cleanUpCardTable() {
6037 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6038 double start = os::elapsedTime();
6039
6040 {
6041 // Iterate over the dirty cards region list.
6042 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6043
6044 workers()->run_task(&cleanup_task);
6045 #ifndef PRODUCT
6046 if (G1VerifyCTCleanup || VerifyAfterGC) {
6047 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6048 heap_region_iterate(&cleanup_verifier);
6049 }
6050 #endif
6051 }
6052
6053 double elapsed = os::elapsedTime() - start;
6054 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6055 }
6056
6057 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6058 size_t pre_used = 0;
6059 FreeRegionList local_free_list("Local List for CSet Freeing");
6060
6061 double young_time_ms = 0.0;
6062 double non_young_time_ms = 0.0;
6063
6064 // Since the collection set is a superset of the the young list,
6065 // all we need to do to clear the young list is clear its
6066 // head and length, and unlink any young regions in the code below
6067 _young_list->clear();
6068
6069 G1CollectorPolicy* policy = g1_policy();
6070
6071 double start_sec = os::elapsedTime();
6072 bool non_young = true;
6073
6074 HeapRegion* cur = cs_head;
6075 int age_bound = -1;
6076 size_t rs_lengths = 0;
6077
6078 while (cur != NULL) {
6079 assert(!is_on_master_free_list(cur), "sanity");
6080 if (non_young) {
6081 if (cur->is_young()) {
6082 double end_sec = os::elapsedTime();
6083 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6084 non_young_time_ms += elapsed_ms;
6085
6086 start_sec = os::elapsedTime();
6087 non_young = false;
6088 }
6089 } else {
6090 if (!cur->is_young()) {
6091 double end_sec = os::elapsedTime();
6092 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6093 young_time_ms += elapsed_ms;
6094
6095 start_sec = os::elapsedTime();
6096 non_young = true;
6097 }
6098 }
6099
6100 rs_lengths += cur->rem_set()->occupied_locked();
6101
6102 HeapRegion* next = cur->next_in_collection_set();
6103 assert(cur->in_collection_set(), "bad CS");
6104 cur->set_next_in_collection_set(NULL);
6105 clear_in_cset(cur);
6106
6107 if (cur->is_young()) {
6108 int index = cur->young_index_in_cset();
6109 assert(index != -1, "invariant");
6110 assert((uint) index < policy->young_cset_region_length(), "invariant");
6111 size_t words_survived = _surviving_young_words[index];
6112 cur->record_surv_words_in_group(words_survived);
6113
6114 // At this point the we have 'popped' cur from the collection set
6115 // (linked via next_in_collection_set()) but it is still in the
6116 // young list (linked via next_young_region()). Clear the
6117 // _next_young_region field.
6118 cur->set_next_young_region(NULL);
6119 } else {
6120 int index = cur->young_index_in_cset();
6121 assert(index == -1, "invariant");
6122 }
6123
6124 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6125 (!cur->is_young() && cur->young_index_in_cset() == -1),
6126 "invariant" );
6127
6128 if (!cur->evacuation_failed()) {
6129 MemRegion used_mr = cur->used_region();
6130
6131 // And the region is empty.
6132 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6133 pre_used += cur->used();
6134 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6135 } else {
6136 cur->uninstall_surv_rate_group();
6137 if (cur->is_young()) {
6138 cur->set_young_index_in_cset(-1);
6139 }
6140 cur->set_evacuation_failed(false);
6141 // The region is now considered to be old.
6142 cur->set_old();
6143 // Do some allocation statistics accounting. Regions that failed evacuation
6144 // are always made old, so there is no need to update anything in the young
6145 // gen statistics, but we need to update old gen statistics.
6146 size_t used_words = cur->marked_bytes() / HeapWordSize;
6147 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6148 _old_set.add(cur);
6149 evacuation_info.increment_collectionset_used_after(cur->used());
6150 }
6151 cur = next;
6152 }
6153
6154 evacuation_info.set_regions_freed(local_free_list.length());
6155 policy->record_max_rs_lengths(rs_lengths);
6156 policy->cset_regions_freed();
6157
6158 double end_sec = os::elapsedTime();
6159 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6160
6161 if (non_young) {
6162 non_young_time_ms += elapsed_ms;
6163 } else {
6164 young_time_ms += elapsed_ms;
6165 }
6166
6167 prepend_to_freelist(&local_free_list);
6168 decrement_summary_bytes(pre_used);
6169 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6170 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6171 }
6172
6173 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6174 private:
6175 FreeRegionList* _free_region_list;
6176 HeapRegionSet* _proxy_set;
6177 HeapRegionSetCount _humongous_regions_removed;
6178 size_t _freed_bytes;
6179 public:
6180
6181 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6182 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6183 }
6184
6185 virtual bool doHeapRegion(HeapRegion* r) {
6186 if (!r->is_starts_humongous()) {
6187 return false;
6188 }
6189
6190 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6191
6192 oop obj = (oop)r->bottom();
6193 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6194
6195 // The following checks whether the humongous object is live are sufficient.
6196 // The main additional check (in addition to having a reference from the roots
6197 // or the young gen) is whether the humongous object has a remembered set entry.
6198 //
6199 // A humongous object cannot be live if there is no remembered set for it
6200 // because:
6201 // - there can be no references from within humongous starts regions referencing
6202 // the object because we never allocate other objects into them.
6203 // (I.e. there are no intra-region references that may be missed by the
6204 // remembered set)
6205 // - as soon there is a remembered set entry to the humongous starts region
6206 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6207 // until the end of a concurrent mark.
6208 //
6209 // It is not required to check whether the object has been found dead by marking
6210 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6211 // all objects allocated during that time are considered live.
6212 // SATB marking is even more conservative than the remembered set.
6213 // So if at this point in the collection there is no remembered set entry,
6214 // nobody has a reference to it.
6215 // At the start of collection we flush all refinement logs, and remembered sets
6216 // are completely up-to-date wrt to references to the humongous object.
6217 //
6218 // Other implementation considerations:
6219 // - never consider object arrays at this time because they would pose
6220 // considerable effort for cleaning up the the remembered sets. This is
6221 // required because stale remembered sets might reference locations that
6222 // are currently allocated into.
6223 uint region_idx = r->hrm_index();
6224 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6225 !r->rem_set()->is_empty()) {
6226
6227 if (G1TraceEagerReclaimHumongousObjects) {
6228 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",
6229 region_idx,
6230 (size_t)obj->size() * HeapWordSize,
6231 p2i(r->bottom()),
6232 r->region_num(),
6233 r->rem_set()->occupied(),
6234 r->rem_set()->strong_code_roots_list_length(),
6235 next_bitmap->isMarked(r->bottom()),
6236 g1h->is_humongous_reclaim_candidate(region_idx),
6237 obj->is_typeArray()
6238 );
6239 }
6240
6241 return false;
6242 }
6243
6244 guarantee(obj->is_typeArray(),
6245 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6246 PTR_FORMAT " is not.",
6247 p2i(r->bottom())));
6248
6249 if (G1TraceEagerReclaimHumongousObjects) {
6250 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",
6251 region_idx,
6252 (size_t)obj->size() * HeapWordSize,
6253 p2i(r->bottom()),
6254 r->region_num(),
6255 r->rem_set()->occupied(),
6256 r->rem_set()->strong_code_roots_list_length(),
6257 next_bitmap->isMarked(r->bottom()),
6258 g1h->is_humongous_reclaim_candidate(region_idx),
6259 obj->is_typeArray()
6260 );
6261 }
6262 // Need to clear mark bit of the humongous object if already set.
6263 if (next_bitmap->isMarked(r->bottom())) {
6264 next_bitmap->clear(r->bottom());
6265 }
6266 _freed_bytes += r->used();
6267 r->set_containing_set(NULL);
6268 _humongous_regions_removed.increment(1u, r->capacity());
6269 g1h->free_humongous_region(r, _free_region_list, false);
6270
6271 return false;
6272 }
6273
6274 HeapRegionSetCount& humongous_free_count() {
6275 return _humongous_regions_removed;
6276 }
6277
6278 size_t bytes_freed() const {
6279 return _freed_bytes;
6280 }
6281
6282 size_t humongous_reclaimed() const {
6283 return _humongous_regions_removed.length();
6284 }
6285 };
6286
6287 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6288 assert_at_safepoint(true);
6289
6290 if (!G1EagerReclaimHumongousObjects ||
6291 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6292 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6293 return;
6294 }
6295
6296 double start_time = os::elapsedTime();
6297
6298 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6299
6300 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6301 heap_region_iterate(&cl);
6302
6303 HeapRegionSetCount empty_set;
6304 remove_from_old_sets(empty_set, cl.humongous_free_count());
6305
6306 G1HRPrinter* hrp = hr_printer();
6307 if (hrp->is_active()) {
6308 FreeRegionListIterator iter(&local_cleanup_list);
6309 while (iter.more_available()) {
6310 HeapRegion* hr = iter.get_next();
6311 hrp->cleanup(hr);
6312 }
6313 }
6314
6315 prepend_to_freelist(&local_cleanup_list);
6316 decrement_summary_bytes(cl.bytes_freed());
6317
6318 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6319 cl.humongous_reclaimed());
6320 }
6321
6322 // This routine is similar to the above but does not record
6323 // any policy statistics or update free lists; we are abandoning
6324 // the current incremental collection set in preparation of a
6325 // full collection. After the full GC we will start to build up
6326 // the incremental collection set again.
6327 // This is only called when we're doing a full collection
6328 // and is immediately followed by the tearing down of the young list.
6329
6330 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6331 HeapRegion* cur = cs_head;
6332
6333 while (cur != NULL) {
6334 HeapRegion* next = cur->next_in_collection_set();
6335 assert(cur->in_collection_set(), "bad CS");
6336 cur->set_next_in_collection_set(NULL);
6337 clear_in_cset(cur);
6338 cur->set_young_index_in_cset(-1);
6339 cur = next;
6340 }
6341 }
6342
6343 void G1CollectedHeap::set_free_regions_coming() {
6344 if (G1ConcRegionFreeingVerbose) {
6345 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6346 "setting free regions coming");
6347 }
6348
6349 assert(!free_regions_coming(), "pre-condition");
6350 _free_regions_coming = true;
6351 }
6352
6353 void G1CollectedHeap::reset_free_regions_coming() {
6354 assert(free_regions_coming(), "pre-condition");
6355
6356 {
6357 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6358 _free_regions_coming = false;
6359 SecondaryFreeList_lock->notify_all();
6360 }
6361
6362 if (G1ConcRegionFreeingVerbose) {
6363 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6364 "reset free regions coming");
6365 }
6366 }
6367
6368 void G1CollectedHeap::wait_while_free_regions_coming() {
6369 // Most of the time we won't have to wait, so let's do a quick test
6370 // first before we take the lock.
6371 if (!free_regions_coming()) {
6372 return;
6373 }
6374
6375 if (G1ConcRegionFreeingVerbose) {
6376 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6377 "waiting for free regions");
6378 }
6379
6380 {
6381 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6382 while (free_regions_coming()) {
6383 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6384 }
6385 }
6386
6387 if (G1ConcRegionFreeingVerbose) {
6388 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6389 "done waiting for free regions");
6390 }
6391 }
6392
6393 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6394 return _allocator->is_retained_old_region(hr);
6395 }
6396
6397 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6398 _young_list->push_region(hr);
6399 }
6400
6401 class NoYoungRegionsClosure: public HeapRegionClosure {
6402 private:
6403 bool _success;
6404 public:
6405 NoYoungRegionsClosure() : _success(true) { }
6406 bool doHeapRegion(HeapRegion* r) {
6407 if (r->is_young()) {
6408 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6409 p2i(r->bottom()), p2i(r->end()));
6410 _success = false;
6411 }
6412 return false;
6413 }
6414 bool success() { return _success; }
6415 };
6416
6417 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6418 bool ret = _young_list->check_list_empty(check_sample);
6419
6420 if (check_heap) {
6421 NoYoungRegionsClosure closure;
6422 heap_region_iterate(&closure);
6423 ret = ret && closure.success();
6424 }
6425
6426 return ret;
6427 }
6428
6429 class TearDownRegionSetsClosure : public HeapRegionClosure {
6430 private:
6431 HeapRegionSet *_old_set;
6432
6433 public:
6434 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6435
6436 bool doHeapRegion(HeapRegion* r) {
6437 if (r->is_old()) {
6438 _old_set->remove(r);
6439 } else {
6440 // We ignore free regions, we'll empty the free list afterwards.
6441 // We ignore young regions, we'll empty the young list afterwards.
6442 // We ignore humongous regions, we're not tearing down the
6443 // humongous regions set.
6444 assert(r->is_free() || r->is_young() || r->is_humongous(),
6445 "it cannot be another type");
6446 }
6447 return false;
6448 }
6449
6450 ~TearDownRegionSetsClosure() {
6451 assert(_old_set->is_empty(), "post-condition");
6452 }
6453 };
6454
6455 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6456 assert_at_safepoint(true /* should_be_vm_thread */);
6457
6458 if (!free_list_only) {
6459 TearDownRegionSetsClosure cl(&_old_set);
6460 heap_region_iterate(&cl);
6461
6462 // Note that emptying the _young_list is postponed and instead done as
6463 // the first step when rebuilding the regions sets again. The reason for
6464 // this is that during a full GC string deduplication needs to know if
6465 // a collected region was young or old when the full GC was initiated.
6466 }
6467 _hrm.remove_all_free_regions();
6468 }
6469
6470 void G1CollectedHeap::increase_used(size_t bytes) {
6471 _summary_bytes_used += bytes;
6472 }
6473
6474 void G1CollectedHeap::decrease_used(size_t bytes) {
6475 assert(_summary_bytes_used >= bytes,
6476 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6477 _summary_bytes_used, bytes));
6478 _summary_bytes_used -= bytes;
6479 }
6480
6481 void G1CollectedHeap::set_used(size_t bytes) {
6482 _summary_bytes_used = bytes;
6483 }
6484
6485 class RebuildRegionSetsClosure : public HeapRegionClosure {
6486 private:
6487 bool _free_list_only;
6488 HeapRegionSet* _old_set;
6489 HeapRegionManager* _hrm;
6490 size_t _total_used;
6491
6492 public:
6493 RebuildRegionSetsClosure(bool free_list_only,
6494 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6495 _free_list_only(free_list_only),
6496 _old_set(old_set), _hrm(hrm), _total_used(0) {
6497 assert(_hrm->num_free_regions() == 0, "pre-condition");
6498 if (!free_list_only) {
6499 assert(_old_set->is_empty(), "pre-condition");
6500 }
6501 }
6502
6503 bool doHeapRegion(HeapRegion* r) {
6504 if (r->is_continues_humongous()) {
6505 return false;
6506 }
6507
6508 if (r->is_empty()) {
6509 // Add free regions to the free list
6510 r->set_free();
6511 r->set_allocation_context(AllocationContext::system());
6512 _hrm->insert_into_free_list(r);
6513 } else if (!_free_list_only) {
6514 assert(!r->is_young(), "we should not come across young regions");
6515
6516 if (r->is_humongous()) {
6517 // We ignore humongous regions. We left the humongous set unchanged.
6518 } else {
6519 // Objects that were compacted would have ended up on regions
6520 // that were previously old or free. Archive regions (which are
6521 // old) will not have been touched.
6522 assert(r->is_free() || r->is_old(), "invariant");
6523 // We now consider them old, so register as such. Leave
6524 // archive regions set that way, however, while still adding
6525 // them to the old set.
6526 if (!r->is_archive()) {
6527 r->set_old();
6528 }
6529 _old_set->add(r);
6530 }
6531 _total_used += r->used();
6532 }
6533
6534 return false;
6535 }
6536
6537 size_t total_used() {
6538 return _total_used;
6539 }
6540 };
6541
6542 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6543 assert_at_safepoint(true /* should_be_vm_thread */);
6544
6545 if (!free_list_only) {
6546 _young_list->empty_list();
6547 }
6548
6549 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6550 heap_region_iterate(&cl);
6551
6552 if (!free_list_only) {
6553 set_used(cl.total_used());
6554 if (_archive_allocator != NULL) {
6555 _archive_allocator->clear_used();
6556 }
6557 }
6558 assert(used_unlocked() == recalculate_used(),
6559 err_msg("inconsistent used_unlocked(), "
6560 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6561 used_unlocked(), recalculate_used()));
6562 }
6563
6564 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6565 _refine_cte_cl->set_concurrent(concurrent);
6566 }
6567
6568 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6569 HeapRegion* hr = heap_region_containing(p);
6570 return hr->is_in(p);
6571 }
6572
6573 // Methods for the mutator alloc region
6574
6575 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6576 bool force) {
6577 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6578 assert(!force || g1_policy()->can_expand_young_list(),
6579 "if force is true we should be able to expand the young list");
6580 bool young_list_full = g1_policy()->is_young_list_full();
6581 if (force || !young_list_full) {
6582 HeapRegion* new_alloc_region = new_region(word_size,
6583 false /* is_old */,
6584 false /* do_expand */);
6585 if (new_alloc_region != NULL) {
6586 set_region_short_lived_locked(new_alloc_region);
6587 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6588 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6589 return new_alloc_region;
6590 }
6591 }
6592 return NULL;
6593 }
6594
6595 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6596 size_t allocated_bytes) {
6597 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6598 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6599
6600 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6601 increase_used(allocated_bytes);
6602 _hr_printer.retire(alloc_region);
6603 // We update the eden sizes here, when the region is retired,
6604 // instead of when it's allocated, since this is the point that its
6605 // used space has been recored in _summary_bytes_used.
6606 g1mm()->update_eden_size();
6607 }
6608
6609 // Methods for the GC alloc regions
6610
6611 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6612 uint count,
6613 InCSetState dest) {
6614 assert(FreeList_lock->owned_by_self(), "pre-condition");
6615
6616 if (count < g1_policy()->max_regions(dest)) {
6617 const bool is_survivor = (dest.is_young());
6618 HeapRegion* new_alloc_region = new_region(word_size,
6619 !is_survivor,
6620 true /* do_expand */);
6621 if (new_alloc_region != NULL) {
6622 // We really only need to do this for old regions given that we
6623 // should never scan survivors. But it doesn't hurt to do it
6624 // for survivors too.
6625 new_alloc_region->record_timestamp();
6626 if (is_survivor) {
6627 new_alloc_region->set_survivor();
6628 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6629 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6630 } else {
6631 new_alloc_region->set_old();
6632 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6633 check_bitmaps("Old Region Allocation", new_alloc_region);
6634 }
6635 bool during_im = collector_state()->during_initial_mark_pause();
6636 new_alloc_region->note_start_of_copying(during_im);
6637 return new_alloc_region;
6638 }
6639 }
6640 return NULL;
6641 }
6642
6643 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6644 size_t allocated_bytes,
6645 InCSetState dest) {
6646 bool during_im = collector_state()->during_initial_mark_pause();
6647 alloc_region->note_end_of_copying(during_im);
6648 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6649 if (dest.is_young()) {
6650 young_list()->add_survivor_region(alloc_region);
6651 } else {
6652 _old_set.add(alloc_region);
6653 }
6654 _hr_printer.retire(alloc_region);
6655 }
6656
6657 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6658 bool expanded = false;
6659 uint index = _hrm.find_highest_free(&expanded);
6660
6661 if (index != G1_NO_HRM_INDEX) {
6662 if (expanded) {
6663 ergo_verbose1(ErgoHeapSizing,
6664 "attempt heap expansion",
6665 ergo_format_reason("requested address range outside heap bounds")
6666 ergo_format_byte("region size"),
6667 HeapRegion::GrainWords * HeapWordSize);
6668 }
6669 _hrm.allocate_free_regions_starting_at(index, 1);
6670 return region_at(index);
6671 }
6672 return NULL;
6673 }
6674
6675 // Heap region set verification
6676
6677 class VerifyRegionListsClosure : public HeapRegionClosure {
6678 private:
6679 HeapRegionSet* _old_set;
6680 HeapRegionSet* _humongous_set;
6681 HeapRegionManager* _hrm;
6682
6683 public:
6684 HeapRegionSetCount _old_count;
6685 HeapRegionSetCount _humongous_count;
6686 HeapRegionSetCount _free_count;
6687
6688 VerifyRegionListsClosure(HeapRegionSet* old_set,
6689 HeapRegionSet* humongous_set,
6690 HeapRegionManager* hrm) :
6691 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6692 _old_count(), _humongous_count(), _free_count(){ }
6693
6694 bool doHeapRegion(HeapRegion* hr) {
6695 if (hr->is_continues_humongous()) {
6696 return false;
6697 }
6698
6699 if (hr->is_young()) {
6700 // TODO
6701 } else if (hr->is_starts_humongous()) {
6702 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6703 _humongous_count.increment(1u, hr->capacity());
6704 } else if (hr->is_empty()) {
6705 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6706 _free_count.increment(1u, hr->capacity());
6707 } else if (hr->is_old()) {
6708 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6709 _old_count.increment(1u, hr->capacity());
6710 } else {
6711 // There are no other valid region types. Check for one invalid
6712 // one we can identify: pinned without old or humongous set.
6713 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6714 ShouldNotReachHere();
6715 }
6716 return false;
6717 }
6718
6719 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6720 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6721 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6722 old_set->total_capacity_bytes(), _old_count.capacity()));
6723
6724 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6725 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6726 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6727
6728 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()));
6729 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6730 free_list->total_capacity_bytes(), _free_count.capacity()));
6731 }
6732 };
6733
6734 void G1CollectedHeap::verify_region_sets() {
6735 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6736
6737 // First, check the explicit lists.
6738 _hrm.verify();
6739 {
6740 // Given that a concurrent operation might be adding regions to
6741 // the secondary free list we have to take the lock before
6742 // verifying it.
6743 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6744 _secondary_free_list.verify_list();
6745 }
6746
6747 // If a concurrent region freeing operation is in progress it will
6748 // be difficult to correctly attributed any free regions we come
6749 // across to the correct free list given that they might belong to
6750 // one of several (free_list, secondary_free_list, any local lists,
6751 // etc.). So, if that's the case we will skip the rest of the
6752 // verification operation. Alternatively, waiting for the concurrent
6753 // operation to complete will have a non-trivial effect on the GC's
6754 // operation (no concurrent operation will last longer than the
6755 // interval between two calls to verification) and it might hide
6756 // any issues that we would like to catch during testing.
6757 if (free_regions_coming()) {
6758 return;
6759 }
6760
6761 // Make sure we append the secondary_free_list on the free_list so
6762 // that all free regions we will come across can be safely
6763 // attributed to the free_list.
6764 append_secondary_free_list_if_not_empty_with_lock();
6765
6766 // Finally, make sure that the region accounting in the lists is
6767 // consistent with what we see in the heap.
6768
6769 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6770 heap_region_iterate(&cl);
6771 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6772 }
6773
6774 // Optimized nmethod scanning
6775
6776 class RegisterNMethodOopClosure: public OopClosure {
6777 G1CollectedHeap* _g1h;
6778 nmethod* _nm;
6779
6780 template <class T> void do_oop_work(T* p) {
6781 T heap_oop = oopDesc::load_heap_oop(p);
6782 if (!oopDesc::is_null(heap_oop)) {
6783 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6784 HeapRegion* hr = _g1h->heap_region_containing(obj);
6785 assert(!hr->is_continues_humongous(),
6786 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6787 " starting at " HR_FORMAT,
6788 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6789
6790 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6791 hr->add_strong_code_root_locked(_nm);
6792 }
6793 }
6794
6795 public:
6796 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6797 _g1h(g1h), _nm(nm) {}
6798
6799 void do_oop(oop* p) { do_oop_work(p); }
6800 void do_oop(narrowOop* p) { do_oop_work(p); }
6801 };
6802
6803 class UnregisterNMethodOopClosure: public OopClosure {
6804 G1CollectedHeap* _g1h;
6805 nmethod* _nm;
6806
6807 template <class T> void do_oop_work(T* p) {
6808 T heap_oop = oopDesc::load_heap_oop(p);
6809 if (!oopDesc::is_null(heap_oop)) {
6810 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6811 HeapRegion* hr = _g1h->heap_region_containing(obj);
6812 assert(!hr->is_continues_humongous(),
6813 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6814 " starting at " HR_FORMAT,
6815 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6816
6817 hr->remove_strong_code_root(_nm);
6818 }
6819 }
6820
6821 public:
6822 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6823 _g1h(g1h), _nm(nm) {}
6824
6825 void do_oop(oop* p) { do_oop_work(p); }
6826 void do_oop(narrowOop* p) { do_oop_work(p); }
6827 };
6828
6829 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6830 CollectedHeap::register_nmethod(nm);
6831
6832 guarantee(nm != NULL, "sanity");
6833 RegisterNMethodOopClosure reg_cl(this, nm);
6834 nm->oops_do(®_cl);
6835 }
6836
6837 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6838 CollectedHeap::unregister_nmethod(nm);
6839
6840 guarantee(nm != NULL, "sanity");
6841 UnregisterNMethodOopClosure reg_cl(this, nm);
6842 nm->oops_do(®_cl, true);
6843 }
6844
6845 void G1CollectedHeap::purge_code_root_memory() {
6846 double purge_start = os::elapsedTime();
6847 G1CodeRootSet::purge();
6848 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6849 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6850 }
6851
6852 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6853 G1CollectedHeap* _g1h;
6854
6855 public:
6856 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6857 _g1h(g1h) {}
6858
6859 void do_code_blob(CodeBlob* cb) {
6860 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6861 if (nm == NULL) {
6862 return;
6863 }
6864
6865 if (ScavengeRootsInCode) {
6866 _g1h->register_nmethod(nm);
6867 }
6868 }
6869 };
6870
6871 void G1CollectedHeap::rebuild_strong_code_roots() {
6872 RebuildStrongCodeRootClosure blob_cl(this);
6873 CodeCache::blobs_do(&blob_cl);
6874 }