1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcId.hpp"
57 #include "gc/shared/gcLocker.inline.hpp"
58 #include "gc/shared/gcTimer.hpp"
59 #include "gc/shared/gcTrace.hpp"
60 #include "gc/shared/gcTraceTime.hpp"
61 #include "gc/shared/generationSpec.hpp"
62 #include "gc/shared/isGCActiveMark.hpp"
63 #include "gc/shared/referenceProcessor.hpp"
64 #include "gc/shared/taskqueue.inline.hpp"
65 #include "memory/allocation.hpp"
66 #include "memory/iterator.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.inline.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
76
77 // INVARIANTS/NOTES
78 //
79 // All allocation activity covered by the G1CollectedHeap interface is
80 // serialized by acquiring the HeapLock. This happens in mem_allocate
81 // and allocate_new_tlab, which are the "entry" points to the
82 // allocation code from the rest of the JVM. (Note that this does not
83 // apply to TLAB allocation, which is not part of this interface: it
84 // is done by clients of this interface.)
85
86 // Local to this file.
87
88 class RefineCardTableEntryClosure: public CardTableEntryClosure {
89 bool _concurrent;
90 public:
91 RefineCardTableEntryClosure() : _concurrent(true) { }
92
93 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
94 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
95 // This path is executed by the concurrent refine or mutator threads,
96 // concurrently, and so we do not care if card_ptr contains references
97 // that point into the collection set.
98 assert(!oops_into_cset, "should be");
99
100 if (_concurrent && SuspendibleThreadSet::should_yield()) {
101 // Caller will actually yield.
102 return false;
103 }
104 // Otherwise, we finished successfully; return true.
105 return true;
106 }
107
108 void set_concurrent(bool b) { _concurrent = b; }
109 };
110
111
112 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
113 private:
114 size_t _num_processed;
115
116 public:
117 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
118
119 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
120 *card_ptr = CardTableModRefBS::dirty_card_val();
121 _num_processed++;
122 return true;
123 }
124
125 size_t num_processed() const { return _num_processed; }
126 };
127
128 YoungList::YoungList(G1CollectedHeap* g1h) :
129 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
130 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
131 guarantee(check_list_empty(false), "just making sure...");
132 }
133
134 void YoungList::push_region(HeapRegion *hr) {
135 assert(!hr->is_young(), "should not already be young");
136 assert(hr->get_next_young_region() == NULL, "cause it should!");
137
138 hr->set_next_young_region(_head);
139 _head = hr;
140
141 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
142 ++_length;
143 }
144
145 void YoungList::add_survivor_region(HeapRegion* hr) {
146 assert(hr->is_survivor(), "should be flagged as survivor region");
147 assert(hr->get_next_young_region() == NULL, "cause it should!");
148
149 hr->set_next_young_region(_survivor_head);
150 if (_survivor_head == NULL) {
151 _survivor_tail = hr;
152 }
153 _survivor_head = hr;
154 ++_survivor_length;
155 }
156
157 void YoungList::empty_list(HeapRegion* list) {
158 while (list != NULL) {
159 HeapRegion* next = list->get_next_young_region();
160 list->set_next_young_region(NULL);
161 list->uninstall_surv_rate_group();
162 // This is called before a Full GC and all the non-empty /
163 // non-humongous regions at the end of the Full GC will end up as
164 // old anyway.
165 list->set_old();
166 list = next;
167 }
168 }
169
170 void YoungList::empty_list() {
171 assert(check_list_well_formed(), "young list should be well formed");
172
173 empty_list(_head);
174 _head = NULL;
175 _length = 0;
176
177 empty_list(_survivor_head);
178 _survivor_head = NULL;
179 _survivor_tail = NULL;
180 _survivor_length = 0;
181
182 _last_sampled_rs_lengths = 0;
183
184 assert(check_list_empty(false), "just making sure...");
185 }
186
187 bool YoungList::check_list_well_formed() {
188 bool ret = true;
189
190 uint length = 0;
191 HeapRegion* curr = _head;
192 HeapRegion* last = NULL;
193 while (curr != NULL) {
194 if (!curr->is_young()) {
195 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
196 "incorrectly tagged (y: %d, surv: %d)",
197 p2i(curr->bottom()), p2i(curr->end()),
198 curr->is_young(), curr->is_survivor());
199 ret = false;
200 }
201 ++length;
202 last = curr;
203 curr = curr->get_next_young_region();
204 }
205 ret = ret && (length == _length);
206
207 if (!ret) {
208 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
209 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
210 length, _length);
211 }
212
213 return ret;
214 }
215
216 bool YoungList::check_list_empty(bool check_sample) {
217 bool ret = true;
218
219 if (_length != 0) {
220 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
221 _length);
222 ret = false;
223 }
224 if (check_sample && _last_sampled_rs_lengths != 0) {
225 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
226 ret = false;
227 }
228 if (_head != NULL) {
229 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
230 ret = false;
231 }
232 if (!ret) {
233 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
234 }
235
236 return ret;
237 }
238
239 void
240 YoungList::rs_length_sampling_init() {
241 _sampled_rs_lengths = 0;
242 _curr = _head;
243 }
244
245 bool
246 YoungList::rs_length_sampling_more() {
247 return _curr != NULL;
248 }
249
250 void
251 YoungList::rs_length_sampling_next() {
252 assert( _curr != NULL, "invariant" );
253 size_t rs_length = _curr->rem_set()->occupied();
254
255 _sampled_rs_lengths += rs_length;
256
257 // The current region may not yet have been added to the
258 // incremental collection set (it gets added when it is
259 // retired as the current allocation region).
260 if (_curr->in_collection_set()) {
261 // Update the collection set policy information for this region
262 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
263 }
264
265 _curr = _curr->get_next_young_region();
266 if (_curr == NULL) {
267 _last_sampled_rs_lengths = _sampled_rs_lengths;
268 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
269 }
270 }
271
272 void
273 YoungList::reset_auxilary_lists() {
274 guarantee( is_empty(), "young list should be empty" );
275 assert(check_list_well_formed(), "young list should be well formed");
276
277 // Add survivor regions to SurvRateGroup.
278 _g1h->g1_policy()->note_start_adding_survivor_regions();
279 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
280
281 int young_index_in_cset = 0;
282 for (HeapRegion* curr = _survivor_head;
283 curr != NULL;
284 curr = curr->get_next_young_region()) {
285 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
286
287 // The region is a non-empty survivor so let's add it to
288 // the incremental collection set for the next evacuation
289 // pause.
290 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
291 young_index_in_cset += 1;
292 }
293 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
294 _g1h->g1_policy()->note_stop_adding_survivor_regions();
295
296 _head = _survivor_head;
297 _length = _survivor_length;
298 if (_survivor_head != NULL) {
299 assert(_survivor_tail != NULL, "cause it shouldn't be");
300 assert(_survivor_length > 0, "invariant");
301 _survivor_tail->set_next_young_region(NULL);
302 }
303
304 // Don't clear the survivor list handles until the start of
305 // the next evacuation pause - we need it in order to re-tag
306 // the survivor regions from this evacuation pause as 'young'
307 // at the start of the next.
308
309 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
310
311 assert(check_list_well_formed(), "young list should be well formed");
312 }
313
314 void YoungList::print() {
315 HeapRegion* lists[] = {_head, _survivor_head};
316 const char* names[] = {"YOUNG", "SURVIVOR"};
317
318 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
319 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
320 HeapRegion *curr = lists[list];
321 if (curr == NULL)
322 gclog_or_tty->print_cr(" empty");
323 while (curr != NULL) {
324 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
325 HR_FORMAT_PARAMS(curr),
326 p2i(curr->prev_top_at_mark_start()),
327 p2i(curr->next_top_at_mark_start()),
328 curr->age_in_surv_rate_group_cond());
329 curr = curr->get_next_young_region();
330 }
331 }
332
333 gclog_or_tty->cr();
334 }
335
336 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
337 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
338 }
339
340 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
341 // The from card cache is not the memory that is actually committed. So we cannot
342 // take advantage of the zero_filled parameter.
343 reset_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
347 {
348 // Claim the right to put the region on the dirty cards region list
349 // by installing a self pointer.
350 HeapRegion* next = hr->get_next_dirty_cards_region();
351 if (next == NULL) {
352 HeapRegion* res = (HeapRegion*)
353 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
354 NULL);
355 if (res == NULL) {
356 HeapRegion* head;
357 do {
358 // Put the region to the dirty cards region list.
359 head = _dirty_cards_region_list;
360 next = (HeapRegion*)
361 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
362 if (next == head) {
363 assert(hr->get_next_dirty_cards_region() == hr,
364 "hr->get_next_dirty_cards_region() != hr");
365 if (next == NULL) {
366 // The last region in the list points to itself.
367 hr->set_next_dirty_cards_region(hr);
368 } else {
369 hr->set_next_dirty_cards_region(next);
370 }
371 }
372 } while (next != head);
373 }
374 }
375 }
376
377 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
378 {
379 HeapRegion* head;
380 HeapRegion* hr;
381 do {
382 head = _dirty_cards_region_list;
383 if (head == NULL) {
384 return NULL;
385 }
386 HeapRegion* new_head = head->get_next_dirty_cards_region();
387 if (head == new_head) {
388 // The last region.
389 new_head = NULL;
390 }
391 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
392 head);
393 } while (hr != head);
394 assert(hr != NULL, "invariant");
395 hr->set_next_dirty_cards_region(NULL);
396 return hr;
397 }
398
399 // Returns true if the reference points to an object that
400 // can move in an incremental collection.
401 bool G1CollectedHeap::is_scavengable(const void* p) {
402 HeapRegion* hr = heap_region_containing(p);
403 return !hr->is_pinned();
404 }
405
406 // Private methods.
407
408 HeapRegion*
409 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
410 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
411 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
412 if (!_secondary_free_list.is_empty()) {
413 if (G1ConcRegionFreeingVerbose) {
414 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
415 "secondary_free_list has %u entries",
416 _secondary_free_list.length());
417 }
418 // It looks as if there are free regions available on the
419 // secondary_free_list. Let's move them to the free_list and try
420 // again to allocate from it.
421 append_secondary_free_list();
422
423 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
424 "empty we should have moved at least one entry to the free_list");
425 HeapRegion* res = _hrm.allocate_free_region(is_old);
426 if (G1ConcRegionFreeingVerbose) {
427 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
428 "allocated " HR_FORMAT " from secondary_free_list",
429 HR_FORMAT_PARAMS(res));
430 }
431 return res;
432 }
433
434 // Wait here until we get notified either when (a) there are no
435 // more free regions coming or (b) some regions have been moved on
436 // the secondary_free_list.
437 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
438 }
439
440 if (G1ConcRegionFreeingVerbose) {
441 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
442 "could not allocate from secondary_free_list");
443 }
444 return NULL;
445 }
446
447 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
448 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
449 "the only time we use this to allocate a humongous region is "
450 "when we are allocating a single humongous region");
451
452 HeapRegion* res;
453 if (G1StressConcRegionFreeing) {
454 if (!_secondary_free_list.is_empty()) {
455 if (G1ConcRegionFreeingVerbose) {
456 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
457 "forced to look at the secondary_free_list");
458 }
459 res = new_region_try_secondary_free_list(is_old);
460 if (res != NULL) {
461 return res;
462 }
463 }
464 }
465
466 res = _hrm.allocate_free_region(is_old);
467
468 if (res == NULL) {
469 if (G1ConcRegionFreeingVerbose) {
470 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
471 "res == NULL, trying the secondary_free_list");
472 }
473 res = new_region_try_secondary_free_list(is_old);
474 }
475 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
476 // Currently, only attempts to allocate GC alloc regions set
477 // do_expand to true. So, we should only reach here during a
478 // safepoint. If this assumption changes we might have to
479 // reconsider the use of _expand_heap_after_alloc_failure.
480 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
481
482 ergo_verbose1(ErgoHeapSizing,
483 "attempt heap expansion",
484 ergo_format_reason("region allocation request failed")
485 ergo_format_byte("allocation request"),
486 word_size * HeapWordSize);
487 if (expand(word_size * HeapWordSize)) {
488 // Given that expand() succeeded in expanding the heap, and we
489 // always expand the heap by an amount aligned to the heap
490 // region size, the free list should in theory not be empty.
491 // In either case allocate_free_region() will check for NULL.
492 res = _hrm.allocate_free_region(is_old);
493 } else {
494 _expand_heap_after_alloc_failure = false;
495 }
496 }
497 return res;
498 }
499
500 HeapWord*
501 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
502 uint num_regions,
503 size_t word_size,
504 AllocationContext_t context) {
505 assert(first != G1_NO_HRM_INDEX, "pre-condition");
506 assert(is_humongous(word_size), "word_size should be humongous");
507 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
508
509 // Index of last region in the series + 1.
510 uint last = first + num_regions;
511
512 // We need to initialize the region(s) we just discovered. This is
513 // a bit tricky given that it can happen concurrently with
514 // refinement threads refining cards on these regions and
515 // potentially wanting to refine the BOT as they are scanning
516 // those cards (this can happen shortly after a cleanup; see CR
517 // 6991377). So we have to set up the region(s) carefully and in
518 // a specific order.
519
520 // The word size sum of all the regions we will allocate.
521 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
522 assert(word_size <= word_size_sum, "sanity");
523
524 // This will be the "starts humongous" region.
525 HeapRegion* first_hr = region_at(first);
526 // The header of the new object will be placed at the bottom of
527 // the first region.
528 HeapWord* new_obj = first_hr->bottom();
529 // This will be the new end of the first region in the series that
530 // should also match the end of the last region in the series.
531 HeapWord* new_end = new_obj + word_size_sum;
532 // This will be the new top of the first region that will reflect
533 // this allocation.
534 HeapWord* new_top = new_obj + word_size;
535
536 // First, we need to zero the header of the space that we will be
537 // allocating. When we update top further down, some refinement
538 // threads might try to scan the region. By zeroing the header we
539 // ensure that any thread that will try to scan the region will
540 // come across the zero klass word and bail out.
541 //
542 // NOTE: It would not have been correct to have used
543 // CollectedHeap::fill_with_object() and make the space look like
544 // an int array. The thread that is doing the allocation will
545 // later update the object header to a potentially different array
546 // type and, for a very short period of time, the klass and length
547 // fields will be inconsistent. This could cause a refinement
548 // thread to calculate the object size incorrectly.
549 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
550
551 // We will set up the first region as "starts humongous". This
552 // will also update the BOT covering all the regions to reflect
553 // that there is a single object that starts at the bottom of the
554 // first region.
555 first_hr->set_starts_humongous(new_top, new_end);
556 first_hr->set_allocation_context(context);
557 // Then, if there are any, we will set up the "continues
558 // humongous" regions.
559 HeapRegion* hr = NULL;
560 for (uint i = first + 1; i < last; ++i) {
561 hr = region_at(i);
562 hr->set_continues_humongous(first_hr);
563 hr->set_allocation_context(context);
564 }
565 // If we have "continues humongous" regions (hr != NULL), then the
566 // end of the last one should match new_end.
567 assert(hr == NULL || hr->end() == new_end, "sanity");
568
569 // Up to this point no concurrent thread would have been able to
570 // do any scanning on any region in this series. All the top
571 // fields still point to bottom, so the intersection between
572 // [bottom,top] and [card_start,card_end] will be empty. Before we
573 // update the top fields, we'll do a storestore to make sure that
574 // no thread sees the update to top before the zeroing of the
575 // object header and the BOT initialization.
576 OrderAccess::storestore();
577
578 // Now that the BOT and the object header have been initialized,
579 // we can update top of the "starts humongous" region.
580 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
581 "new_top should be in this region");
582 first_hr->set_top(new_top);
583 if (_hr_printer.is_active()) {
584 HeapWord* bottom = first_hr->bottom();
585 HeapWord* end = first_hr->orig_end();
586 if ((first + 1) == last) {
587 // the series has a single humongous region
588 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
589 } else {
590 // the series has more than one humongous regions
591 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
592 }
593 }
594
595 // Now, we will update the top fields of the "continues humongous"
596 // regions. The reason we need to do this is that, otherwise,
597 // these regions would look empty and this will confuse parts of
598 // G1. For example, the code that looks for a consecutive number
599 // of empty regions will consider them empty and try to
600 // re-allocate them. We can extend is_empty() to also include
601 // !is_continues_humongous(), but it is easier to just update the top
602 // fields here. The way we set top for all regions (i.e., top ==
603 // end for all regions but the last one, top == new_top for the
604 // last one) is actually used when we will free up the humongous
605 // region in free_humongous_region().
606 hr = NULL;
607 for (uint i = first + 1; i < last; ++i) {
608 hr = region_at(i);
609 if ((i + 1) == last) {
610 // last continues humongous region
611 assert(hr->bottom() < new_top && new_top <= hr->end(),
612 "new_top should fall on this region");
613 hr->set_top(new_top);
614 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
615 } else {
616 // not last one
617 assert(new_top > hr->end(), "new_top should be above this region");
618 hr->set_top(hr->end());
619 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
620 }
621 }
622 // If we have continues humongous regions (hr != NULL), then the
623 // end of the last one should match new_end and its top should
624 // match new_top.
625 assert(hr == NULL ||
626 (hr->end() == new_end && hr->top() == new_top), "sanity");
627 check_bitmaps("Humongous Region Allocation", first_hr);
628
629 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
630 increase_used(first_hr->used());
631 _humongous_set.add(first_hr);
632
633 return new_obj;
634 }
635
636 // If could fit into free regions w/o expansion, try.
637 // Otherwise, if can expand, do so.
638 // Otherwise, if using ex regions might help, try with ex given back.
639 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
640 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
641
642 verify_region_sets_optional();
643
644 uint first = G1_NO_HRM_INDEX;
645 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
646
647 if (obj_regions == 1) {
648 // Only one region to allocate, try to use a fast path by directly allocating
649 // from the free lists. Do not try to expand here, we will potentially do that
650 // later.
651 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
652 if (hr != NULL) {
653 first = hr->hrm_index();
654 }
655 } else {
656 // We can't allocate humongous regions spanning more than one region while
657 // cleanupComplete() is running, since some of the regions we find to be
658 // empty might not yet be added to the free list. It is not straightforward
659 // to know in which list they are on so that we can remove them. We only
660 // need to do this if we need to allocate more than one region to satisfy the
661 // current humongous allocation request. If we are only allocating one region
662 // we use the one-region region allocation code (see above), that already
663 // potentially waits for regions from the secondary free list.
664 wait_while_free_regions_coming();
665 append_secondary_free_list_if_not_empty_with_lock();
666
667 // Policy: Try only empty regions (i.e. already committed first). Maybe we
668 // are lucky enough to find some.
669 first = _hrm.find_contiguous_only_empty(obj_regions);
670 if (first != G1_NO_HRM_INDEX) {
671 _hrm.allocate_free_regions_starting_at(first, obj_regions);
672 }
673 }
674
675 if (first == G1_NO_HRM_INDEX) {
676 // Policy: We could not find enough regions for the humongous object in the
677 // free list. Look through the heap to find a mix of free and uncommitted regions.
678 // If so, try expansion.
679 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
680 if (first != G1_NO_HRM_INDEX) {
681 // We found something. Make sure these regions are committed, i.e. expand
682 // the heap. Alternatively we could do a defragmentation GC.
683 ergo_verbose1(ErgoHeapSizing,
684 "attempt heap expansion",
685 ergo_format_reason("humongous allocation request failed")
686 ergo_format_byte("allocation request"),
687 word_size * HeapWordSize);
688
689 _hrm.expand_at(first, obj_regions);
690 g1_policy()->record_new_heap_size(num_regions());
691
692 #ifdef ASSERT
693 for (uint i = first; i < first + obj_regions; ++i) {
694 HeapRegion* hr = region_at(i);
695 assert(hr->is_free(), "sanity");
696 assert(hr->is_empty(), "sanity");
697 assert(is_on_master_free_list(hr), "sanity");
698 }
699 #endif
700 _hrm.allocate_free_regions_starting_at(first, obj_regions);
701 } else {
702 // Policy: Potentially trigger a defragmentation GC.
703 }
704 }
705
706 HeapWord* result = NULL;
707 if (first != G1_NO_HRM_INDEX) {
708 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
709 word_size, context);
710 assert(result != NULL, "it should always return a valid result");
711
712 // A successful humongous object allocation changes the used space
713 // information of the old generation so we need to recalculate the
714 // sizes and update the jstat counters here.
715 g1mm()->update_sizes();
716 }
717
718 verify_region_sets_optional();
719
720 return result;
721 }
722
723 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
724 assert_heap_not_locked_and_not_at_safepoint();
725 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
726
727 uint dummy_gc_count_before;
728 uint dummy_gclocker_retry_count = 0;
729 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
730 }
731
732 HeapWord*
733 G1CollectedHeap::mem_allocate(size_t word_size,
734 bool* gc_overhead_limit_was_exceeded) {
735 assert_heap_not_locked_and_not_at_safepoint();
736
737 // Loop until the allocation is satisfied, or unsatisfied after GC.
738 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
739 uint gc_count_before;
740
741 HeapWord* result = NULL;
742 if (!is_humongous(word_size)) {
743 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
744 } else {
745 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
746 }
747 if (result != NULL) {
748 return result;
749 }
750
751 // Create the garbage collection operation...
752 VM_G1CollectForAllocation op(gc_count_before, word_size);
753 op.set_allocation_context(AllocationContext::current());
754
755 // ...and get the VM thread to execute it.
756 VMThread::execute(&op);
757
758 if (op.prologue_succeeded() && op.pause_succeeded()) {
759 // If the operation was successful we'll return the result even
760 // if it is NULL. If the allocation attempt failed immediately
761 // after a Full GC, it's unlikely we'll be able to allocate now.
762 HeapWord* result = op.result();
763 if (result != NULL && !is_humongous(word_size)) {
764 // Allocations that take place on VM operations do not do any
765 // card dirtying and we have to do it here. We only have to do
766 // this for non-humongous allocations, though.
767 dirty_young_block(result, word_size);
768 }
769 return result;
770 } else {
771 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
772 return NULL;
773 }
774 assert(op.result() == NULL,
775 "the result should be NULL if the VM op did not succeed");
776 }
777
778 // Give a warning if we seem to be looping forever.
779 if ((QueuedAllocationWarningCount > 0) &&
780 (try_count % QueuedAllocationWarningCount == 0)) {
781 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
782 }
783 }
784
785 ShouldNotReachHere();
786 return NULL;
787 }
788
789 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
790 AllocationContext_t context,
791 uint* gc_count_before_ret,
792 uint* gclocker_retry_count_ret) {
793 // Make sure you read the note in attempt_allocation_humongous().
794
795 assert_heap_not_locked_and_not_at_safepoint();
796 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
797 "be called for humongous allocation requests");
798
799 // We should only get here after the first-level allocation attempt
800 // (attempt_allocation()) failed to allocate.
801
802 // We will loop until a) we manage to successfully perform the
803 // allocation or b) we successfully schedule a collection which
804 // fails to perform the allocation. b) is the only case when we'll
805 // return NULL.
806 HeapWord* result = NULL;
807 for (int try_count = 1; /* we'll return */; try_count += 1) {
808 bool should_try_gc;
809 uint gc_count_before;
810
811 {
812 MutexLockerEx x(Heap_lock);
813 result = _allocator->attempt_allocation_locked(word_size, context);
814 if (result != NULL) {
815 return result;
816 }
817
818 if (GC_locker::is_active_and_needs_gc()) {
819 if (g1_policy()->can_expand_young_list()) {
820 // No need for an ergo verbose message here,
821 // can_expand_young_list() does this when it returns true.
822 result = _allocator->attempt_allocation_force(word_size, context);
823 if (result != NULL) {
824 return result;
825 }
826 }
827 should_try_gc = false;
828 } else {
829 // The GCLocker may not be active but the GCLocker initiated
830 // GC may not yet have been performed (GCLocker::needs_gc()
831 // returns true). In this case we do not try this GC and
832 // wait until the GCLocker initiated GC is performed, and
833 // then retry the allocation.
834 if (GC_locker::needs_gc()) {
835 should_try_gc = false;
836 } else {
837 // Read the GC count while still holding the Heap_lock.
838 gc_count_before = total_collections();
839 should_try_gc = true;
840 }
841 }
842 }
843
844 if (should_try_gc) {
845 bool succeeded;
846 result = do_collection_pause(word_size, gc_count_before, &succeeded,
847 GCCause::_g1_inc_collection_pause);
848 if (result != NULL) {
849 assert(succeeded, "only way to get back a non-NULL result");
850 return result;
851 }
852
853 if (succeeded) {
854 // If we get here we successfully scheduled a collection which
855 // failed to allocate. No point in trying to allocate
856 // further. We'll just return NULL.
857 MutexLockerEx x(Heap_lock);
858 *gc_count_before_ret = total_collections();
859 return NULL;
860 }
861 } else {
862 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
863 MutexLockerEx x(Heap_lock);
864 *gc_count_before_ret = total_collections();
865 return NULL;
866 }
867 // The GCLocker is either active or the GCLocker initiated
868 // GC has not yet been performed. Stall until it is and
869 // then retry the allocation.
870 GC_locker::stall_until_clear();
871 (*gclocker_retry_count_ret) += 1;
872 }
873
874 // We can reach here if we were unsuccessful in scheduling a
875 // collection (because another thread beat us to it) or if we were
876 // stalled due to the GC locker. In either can we should retry the
877 // allocation attempt in case another thread successfully
878 // performed a collection and reclaimed enough space. We do the
879 // first attempt (without holding the Heap_lock) here and the
880 // follow-on attempt will be at the start of the next loop
881 // iteration (after taking the Heap_lock).
882 result = _allocator->attempt_allocation(word_size, context);
883 if (result != NULL) {
884 return result;
885 }
886
887 // Give a warning if we seem to be looping forever.
888 if ((QueuedAllocationWarningCount > 0) &&
889 (try_count % QueuedAllocationWarningCount == 0)) {
890 warning("G1CollectedHeap::attempt_allocation_slow() "
891 "retries %d times", try_count);
892 }
893 }
894
895 ShouldNotReachHere();
896 return NULL;
897 }
898
899 void G1CollectedHeap::begin_archive_alloc_range() {
900 assert_at_safepoint(true /* should_be_vm_thread */);
901 if (_archive_allocator == NULL) {
902 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
903 }
904 }
905
906 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
907 // Allocations in archive regions cannot be of a size that would be considered
908 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
909 // may be different at archive-restore time.
910 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
911 }
912
913 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
914 assert_at_safepoint(true /* should_be_vm_thread */);
915 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
916 if (is_archive_alloc_too_large(word_size)) {
917 return NULL;
918 }
919 return _archive_allocator->archive_mem_allocate(word_size);
920 }
921
922 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
923 size_t end_alignment_in_bytes) {
924 assert_at_safepoint(true /* should_be_vm_thread */);
925 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
926
927 // Call complete_archive to do the real work, filling in the MemRegion
928 // array with the archive regions.
929 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
930 delete _archive_allocator;
931 _archive_allocator = NULL;
932 }
933
934 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
935 assert(ranges != NULL, "MemRegion array NULL");
936 assert(count != 0, "No MemRegions provided");
937 MemRegion reserved = _hrm.reserved();
938 for (size_t i = 0; i < count; i++) {
939 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
940 return false;
941 }
942 }
943 return true;
944 }
945
946 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
947 assert(!is_init_completed(), "Expect to be called at JVM init time");
948 assert(ranges != NULL, "MemRegion array NULL");
949 assert(count != 0, "No MemRegions provided");
950 MutexLockerEx x(Heap_lock);
951
952 MemRegion reserved = _hrm.reserved();
953 HeapWord* prev_last_addr = NULL;
954 HeapRegion* prev_last_region = NULL;
955
956 // Temporarily disable pretouching of heap pages. This interface is used
957 // when mmap'ing archived heap data in, so pre-touching is wasted.
958 FlagSetting fs(AlwaysPreTouch, false);
959
960 // Enable archive object checking in G1MarkSweep. We have to let it know
961 // about each archive range, so that objects in those ranges aren't marked.
962 G1MarkSweep::enable_archive_object_check();
963
964 // For each specified MemRegion range, allocate the corresponding G1
965 // regions and mark them as archive regions. We expect the ranges in
966 // ascending starting address order, without overlap.
967 for (size_t i = 0; i < count; i++) {
968 MemRegion curr_range = ranges[i];
969 HeapWord* start_address = curr_range.start();
970 size_t word_size = curr_range.word_size();
971 HeapWord* last_address = curr_range.last();
972 size_t commits = 0;
973
974 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
975 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
976 p2i(start_address), p2i(last_address));
977 guarantee(start_address > prev_last_addr,
978 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
979 p2i(start_address), p2i(prev_last_addr));
980 prev_last_addr = last_address;
981
982 // Check for ranges that start in the same G1 region in which the previous
983 // range ended, and adjust the start address so we don't try to allocate
984 // the same region again. If the current range is entirely within that
985 // region, skip it, just adjusting the recorded top.
986 HeapRegion* start_region = _hrm.addr_to_region(start_address);
987 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
988 start_address = start_region->end();
989 if (start_address > last_address) {
990 increase_used(word_size * HeapWordSize);
991 start_region->set_top(last_address + 1);
992 continue;
993 }
994 start_region->set_top(start_address);
995 curr_range = MemRegion(start_address, last_address + 1);
996 start_region = _hrm.addr_to_region(start_address);
997 }
998
999 // Perform the actual region allocation, exiting if it fails.
1000 // Then note how much new space we have allocated.
1001 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1002 return false;
1003 }
1004 increase_used(word_size * HeapWordSize);
1005 if (commits != 0) {
1006 ergo_verbose1(ErgoHeapSizing,
1007 "attempt heap expansion",
1008 ergo_format_reason("allocate archive regions")
1009 ergo_format_byte("total size"),
1010 HeapRegion::GrainWords * HeapWordSize * commits);
1011 }
1012
1013 // Mark each G1 region touched by the range as archive, add it to the old set,
1014 // and set the allocation context and top.
1015 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1016 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1017 prev_last_region = last_region;
1018
1019 while (curr_region != NULL) {
1020 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1021 "Region already in use (index %u)", curr_region->hrm_index());
1022 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1023 curr_region->set_allocation_context(AllocationContext::system());
1024 curr_region->set_archive();
1025 _old_set.add(curr_region);
1026 if (curr_region != last_region) {
1027 curr_region->set_top(curr_region->end());
1028 curr_region = _hrm.next_region_in_heap(curr_region);
1029 } else {
1030 curr_region->set_top(last_address + 1);
1031 curr_region = NULL;
1032 }
1033 }
1034
1035 // Notify mark-sweep of the archive range.
1036 G1MarkSweep::set_range_archive(curr_range, true);
1037 }
1038 return true;
1039 }
1040
1041 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1042 assert(!is_init_completed(), "Expect to be called at JVM init time");
1043 assert(ranges != NULL, "MemRegion array NULL");
1044 assert(count != 0, "No MemRegions provided");
1045 MemRegion reserved = _hrm.reserved();
1046 HeapWord *prev_last_addr = NULL;
1047 HeapRegion* prev_last_region = NULL;
1048
1049 // For each MemRegion, create filler objects, if needed, in the G1 regions
1050 // that contain the address range. The address range actually within the
1051 // MemRegion will not be modified. That is assumed to have been initialized
1052 // elsewhere, probably via an mmap of archived heap data.
1053 MutexLockerEx x(Heap_lock);
1054 for (size_t i = 0; i < count; i++) {
1055 HeapWord* start_address = ranges[i].start();
1056 HeapWord* last_address = ranges[i].last();
1057
1058 assert(reserved.contains(start_address) && reserved.contains(last_address),
1059 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1060 p2i(start_address), p2i(last_address));
1061 assert(start_address > prev_last_addr,
1062 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1063 p2i(start_address), p2i(prev_last_addr));
1064
1065 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1066 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1067 HeapWord* bottom_address = start_region->bottom();
1068
1069 // Check for a range beginning in the same region in which the
1070 // previous one ended.
1071 if (start_region == prev_last_region) {
1072 bottom_address = prev_last_addr + 1;
1073 }
1074
1075 // Verify that the regions were all marked as archive regions by
1076 // alloc_archive_regions.
1077 HeapRegion* curr_region = start_region;
1078 while (curr_region != NULL) {
1079 guarantee(curr_region->is_archive(),
1080 "Expected archive region at index %u", curr_region->hrm_index());
1081 if (curr_region != last_region) {
1082 curr_region = _hrm.next_region_in_heap(curr_region);
1083 } else {
1084 curr_region = NULL;
1085 }
1086 }
1087
1088 prev_last_addr = last_address;
1089 prev_last_region = last_region;
1090
1091 // Fill the memory below the allocated range with dummy object(s),
1092 // if the region bottom does not match the range start, or if the previous
1093 // range ended within the same G1 region, and there is a gap.
1094 if (start_address != bottom_address) {
1095 size_t fill_size = pointer_delta(start_address, bottom_address);
1096 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1097 increase_used(fill_size * HeapWordSize);
1098 }
1099 }
1100 }
1101
1102 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1103 uint* gc_count_before_ret,
1104 uint* gclocker_retry_count_ret) {
1105 assert_heap_not_locked_and_not_at_safepoint();
1106 assert(!is_humongous(word_size), "attempt_allocation() should not "
1107 "be called for humongous allocation requests");
1108
1109 AllocationContext_t context = AllocationContext::current();
1110 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1111
1112 if (result == NULL) {
1113 result = attempt_allocation_slow(word_size,
1114 context,
1115 gc_count_before_ret,
1116 gclocker_retry_count_ret);
1117 }
1118 assert_heap_not_locked();
1119 if (result != NULL) {
1120 dirty_young_block(result, word_size);
1121 }
1122 return result;
1123 }
1124
1125 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1126 assert(!is_init_completed(), "Expect to be called at JVM init time");
1127 assert(ranges != NULL, "MemRegion array NULL");
1128 assert(count != 0, "No MemRegions provided");
1129 MemRegion reserved = _hrm.reserved();
1130 HeapWord* prev_last_addr = NULL;
1131 HeapRegion* prev_last_region = NULL;
1132 size_t size_used = 0;
1133 size_t uncommitted_regions = 0;
1134
1135 // For each Memregion, free the G1 regions that constitute it, and
1136 // notify mark-sweep that the range is no longer to be considered 'archive.'
1137 MutexLockerEx x(Heap_lock);
1138 for (size_t i = 0; i < count; i++) {
1139 HeapWord* start_address = ranges[i].start();
1140 HeapWord* last_address = ranges[i].last();
1141
1142 assert(reserved.contains(start_address) && reserved.contains(last_address),
1143 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1144 p2i(start_address), p2i(last_address));
1145 assert(start_address > prev_last_addr,
1146 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1147 p2i(start_address), p2i(prev_last_addr));
1148 size_used += ranges[i].byte_size();
1149 prev_last_addr = last_address;
1150
1151 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1152 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1153
1154 // Check for ranges that start in the same G1 region in which the previous
1155 // range ended, and adjust the start address so we don't try to free
1156 // the same region again. If the current range is entirely within that
1157 // region, skip it.
1158 if (start_region == prev_last_region) {
1159 start_address = start_region->end();
1160 if (start_address > last_address) {
1161 continue;
1162 }
1163 start_region = _hrm.addr_to_region(start_address);
1164 }
1165 prev_last_region = last_region;
1166
1167 // After verifying that each region was marked as an archive region by
1168 // alloc_archive_regions, set it free and empty and uncommit it.
1169 HeapRegion* curr_region = start_region;
1170 while (curr_region != NULL) {
1171 guarantee(curr_region->is_archive(),
1172 "Expected archive region at index %u", curr_region->hrm_index());
1173 uint curr_index = curr_region->hrm_index();
1174 _old_set.remove(curr_region);
1175 curr_region->set_free();
1176 curr_region->set_top(curr_region->bottom());
1177 if (curr_region != last_region) {
1178 curr_region = _hrm.next_region_in_heap(curr_region);
1179 } else {
1180 curr_region = NULL;
1181 }
1182 _hrm.shrink_at(curr_index, 1);
1183 uncommitted_regions++;
1184 }
1185
1186 // Notify mark-sweep that this is no longer an archive range.
1187 G1MarkSweep::set_range_archive(ranges[i], false);
1188 }
1189
1190 if (uncommitted_regions != 0) {
1191 ergo_verbose1(ErgoHeapSizing,
1192 "attempt heap shrinking",
1193 ergo_format_reason("uncommitted archive regions")
1194 ergo_format_byte("total size"),
1195 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1196 }
1197 decrease_used(size_used);
1198 }
1199
1200 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1201 uint* gc_count_before_ret,
1202 uint* gclocker_retry_count_ret) {
1203 // The structure of this method has a lot of similarities to
1204 // attempt_allocation_slow(). The reason these two were not merged
1205 // into a single one is that such a method would require several "if
1206 // allocation is not humongous do this, otherwise do that"
1207 // conditional paths which would obscure its flow. In fact, an early
1208 // version of this code did use a unified method which was harder to
1209 // follow and, as a result, it had subtle bugs that were hard to
1210 // track down. So keeping these two methods separate allows each to
1211 // be more readable. It will be good to keep these two in sync as
1212 // much as possible.
1213
1214 assert_heap_not_locked_and_not_at_safepoint();
1215 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1216 "should only be called for humongous allocations");
1217
1218 // Humongous objects can exhaust the heap quickly, so we should check if we
1219 // need to start a marking cycle at each humongous object allocation. We do
1220 // the check before we do the actual allocation. The reason for doing it
1221 // before the allocation is that we avoid having to keep track of the newly
1222 // allocated memory while we do a GC.
1223 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1224 word_size)) {
1225 collect(GCCause::_g1_humongous_allocation);
1226 }
1227
1228 // We will loop until a) we manage to successfully perform the
1229 // allocation or b) we successfully schedule a collection which
1230 // fails to perform the allocation. b) is the only case when we'll
1231 // return NULL.
1232 HeapWord* result = NULL;
1233 for (int try_count = 1; /* we'll return */; try_count += 1) {
1234 bool should_try_gc;
1235 uint gc_count_before;
1236
1237 {
1238 MutexLockerEx x(Heap_lock);
1239
1240 // Given that humongous objects are not allocated in young
1241 // regions, we'll first try to do the allocation without doing a
1242 // collection hoping that there's enough space in the heap.
1243 result = humongous_obj_allocate(word_size, AllocationContext::current());
1244 if (result != NULL) {
1245 return result;
1246 }
1247
1248 if (GC_locker::is_active_and_needs_gc()) {
1249 should_try_gc = false;
1250 } else {
1251 // The GCLocker may not be active but the GCLocker initiated
1252 // GC may not yet have been performed (GCLocker::needs_gc()
1253 // returns true). In this case we do not try this GC and
1254 // wait until the GCLocker initiated GC is performed, and
1255 // then retry the allocation.
1256 if (GC_locker::needs_gc()) {
1257 should_try_gc = false;
1258 } else {
1259 // Read the GC count while still holding the Heap_lock.
1260 gc_count_before = total_collections();
1261 should_try_gc = true;
1262 }
1263 }
1264 }
1265
1266 if (should_try_gc) {
1267 // If we failed to allocate the humongous object, we should try to
1268 // do a collection pause (if we're allowed) in case it reclaims
1269 // enough space for the allocation to succeed after the pause.
1270
1271 bool succeeded;
1272 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1273 GCCause::_g1_humongous_allocation);
1274 if (result != NULL) {
1275 assert(succeeded, "only way to get back a non-NULL result");
1276 return result;
1277 }
1278
1279 if (succeeded) {
1280 // If we get here we successfully scheduled a collection which
1281 // failed to allocate. No point in trying to allocate
1282 // further. We'll just return NULL.
1283 MutexLockerEx x(Heap_lock);
1284 *gc_count_before_ret = total_collections();
1285 return NULL;
1286 }
1287 } else {
1288 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1289 MutexLockerEx x(Heap_lock);
1290 *gc_count_before_ret = total_collections();
1291 return NULL;
1292 }
1293 // The GCLocker is either active or the GCLocker initiated
1294 // GC has not yet been performed. Stall until it is and
1295 // then retry the allocation.
1296 GC_locker::stall_until_clear();
1297 (*gclocker_retry_count_ret) += 1;
1298 }
1299
1300 // We can reach here if we were unsuccessful in scheduling a
1301 // collection (because another thread beat us to it) or if we were
1302 // stalled due to the GC locker. In either can we should retry the
1303 // allocation attempt in case another thread successfully
1304 // performed a collection and reclaimed enough space. Give a
1305 // warning if we seem to be looping forever.
1306
1307 if ((QueuedAllocationWarningCount > 0) &&
1308 (try_count % QueuedAllocationWarningCount == 0)) {
1309 warning("G1CollectedHeap::attempt_allocation_humongous() "
1310 "retries %d times", try_count);
1311 }
1312 }
1313
1314 ShouldNotReachHere();
1315 return NULL;
1316 }
1317
1318 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1319 AllocationContext_t context,
1320 bool expect_null_mutator_alloc_region) {
1321 assert_at_safepoint(true /* should_be_vm_thread */);
1322 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1323 "the current alloc region was unexpectedly found to be non-NULL");
1324
1325 if (!is_humongous(word_size)) {
1326 return _allocator->attempt_allocation_locked(word_size, context);
1327 } else {
1328 HeapWord* result = humongous_obj_allocate(word_size, context);
1329 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1330 collector_state()->set_initiate_conc_mark_if_possible(true);
1331 }
1332 return result;
1333 }
1334
1335 ShouldNotReachHere();
1336 }
1337
1338 class PostMCRemSetClearClosure: public HeapRegionClosure {
1339 G1CollectedHeap* _g1h;
1340 ModRefBarrierSet* _mr_bs;
1341 public:
1342 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1343 _g1h(g1h), _mr_bs(mr_bs) {}
1344
1345 bool doHeapRegion(HeapRegion* r) {
1346 HeapRegionRemSet* hrrs = r->rem_set();
1347
1348 if (r->is_continues_humongous()) {
1349 // We'll assert that the strong code root list and RSet is empty
1350 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1351 assert(hrrs->occupied() == 0, "RSet should be empty");
1352 return false;
1353 }
1354
1355 _g1h->reset_gc_time_stamps(r);
1356 hrrs->clear();
1357 // You might think here that we could clear just the cards
1358 // corresponding to the used region. But no: if we leave a dirty card
1359 // in a region we might allocate into, then it would prevent that card
1360 // from being enqueued, and cause it to be missed.
1361 // Re: the performance cost: we shouldn't be doing full GC anyway!
1362 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1363
1364 return false;
1365 }
1366 };
1367
1368 void G1CollectedHeap::clear_rsets_post_compaction() {
1369 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1370 heap_region_iterate(&rs_clear);
1371 }
1372
1373 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1374 G1CollectedHeap* _g1h;
1375 UpdateRSOopClosure _cl;
1376 public:
1377 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1378 _cl(g1->g1_rem_set(), worker_i),
1379 _g1h(g1)
1380 { }
1381
1382 bool doHeapRegion(HeapRegion* r) {
1383 if (!r->is_continues_humongous()) {
1384 _cl.set_from(r);
1385 r->oop_iterate(&_cl);
1386 }
1387 return false;
1388 }
1389 };
1390
1391 class ParRebuildRSTask: public AbstractGangTask {
1392 G1CollectedHeap* _g1;
1393 HeapRegionClaimer _hrclaimer;
1394
1395 public:
1396 ParRebuildRSTask(G1CollectedHeap* g1) :
1397 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1398
1399 void work(uint worker_id) {
1400 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1401 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1402 }
1403 };
1404
1405 class PostCompactionPrinterClosure: public HeapRegionClosure {
1406 private:
1407 G1HRPrinter* _hr_printer;
1408 public:
1409 bool doHeapRegion(HeapRegion* hr) {
1410 assert(!hr->is_young(), "not expecting to find young regions");
1411 if (hr->is_free()) {
1412 // We only generate output for non-empty regions.
1413 } else if (hr->is_starts_humongous()) {
1414 if (hr->region_num() == 1) {
1415 // single humongous region
1416 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1417 } else {
1418 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1419 }
1420 } else if (hr->is_continues_humongous()) {
1421 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1422 } else if (hr->is_archive()) {
1423 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1424 } else if (hr->is_old()) {
1425 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1426 } else {
1427 ShouldNotReachHere();
1428 }
1429 return false;
1430 }
1431
1432 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1433 : _hr_printer(hr_printer) { }
1434 };
1435
1436 void G1CollectedHeap::print_hrm_post_compaction() {
1437 PostCompactionPrinterClosure cl(hr_printer());
1438 heap_region_iterate(&cl);
1439 }
1440
1441 bool G1CollectedHeap::do_collection(bool explicit_gc,
1442 bool clear_all_soft_refs,
1443 size_t word_size) {
1444 assert_at_safepoint(true /* should_be_vm_thread */);
1445
1446 if (GC_locker::check_active_before_gc()) {
1447 return false;
1448 }
1449
1450 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1451 gc_timer->register_gc_start();
1452
1453 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1454 GCIdMark gc_id_mark;
1455 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1456
1457 SvcGCMarker sgcm(SvcGCMarker::FULL);
1458 ResourceMark rm;
1459
1460 G1Log::update_level();
1461 print_heap_before_gc();
1462 trace_heap_before_gc(gc_tracer);
1463
1464 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1465
1466 verify_region_sets_optional();
1467
1468 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1469 collector_policy()->should_clear_all_soft_refs();
1470
1471 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1472
1473 {
1474 IsGCActiveMark x;
1475
1476 // Timing
1477 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1478 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1479
1480 {
1481 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1482 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1483 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1484
1485 g1_policy()->record_full_collection_start();
1486
1487 // Note: When we have a more flexible GC logging framework that
1488 // allows us to add optional attributes to a GC log record we
1489 // could consider timing and reporting how long we wait in the
1490 // following two methods.
1491 wait_while_free_regions_coming();
1492 // If we start the compaction before the CM threads finish
1493 // scanning the root regions we might trip them over as we'll
1494 // be moving objects / updating references. So let's wait until
1495 // they are done. By telling them to abort, they should complete
1496 // early.
1497 _cm->root_regions()->abort();
1498 _cm->root_regions()->wait_until_scan_finished();
1499 append_secondary_free_list_if_not_empty_with_lock();
1500
1501 gc_prologue(true);
1502 increment_total_collections(true /* full gc */);
1503 increment_old_marking_cycles_started();
1504
1505 assert(used() == recalculate_used(), "Should be equal");
1506
1507 verify_before_gc();
1508
1509 check_bitmaps("Full GC Start");
1510 pre_full_gc_dump(gc_timer);
1511
1512 COMPILER2_PRESENT(DerivedPointerTable::clear());
1513
1514 // Disable discovery and empty the discovered lists
1515 // for the CM ref processor.
1516 ref_processor_cm()->disable_discovery();
1517 ref_processor_cm()->abandon_partial_discovery();
1518 ref_processor_cm()->verify_no_references_recorded();
1519
1520 // Abandon current iterations of concurrent marking and concurrent
1521 // refinement, if any are in progress. We have to do this before
1522 // wait_until_scan_finished() below.
1523 concurrent_mark()->abort();
1524
1525 // Make sure we'll choose a new allocation region afterwards.
1526 _allocator->release_mutator_alloc_region();
1527 _allocator->abandon_gc_alloc_regions();
1528 g1_rem_set()->cleanupHRRS();
1529
1530 // We should call this after we retire any currently active alloc
1531 // regions so that all the ALLOC / RETIRE events are generated
1532 // before the start GC event.
1533 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1534
1535 // We may have added regions to the current incremental collection
1536 // set between the last GC or pause and now. We need to clear the
1537 // incremental collection set and then start rebuilding it afresh
1538 // after this full GC.
1539 abandon_collection_set(g1_policy()->inc_cset_head());
1540 g1_policy()->clear_incremental_cset();
1541 g1_policy()->stop_incremental_cset_building();
1542
1543 tear_down_region_sets(false /* free_list_only */);
1544 collector_state()->set_gcs_are_young(true);
1545
1546 // See the comments in g1CollectedHeap.hpp and
1547 // G1CollectedHeap::ref_processing_init() about
1548 // how reference processing currently works in G1.
1549
1550 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1551 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1552
1553 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1554 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1555
1556 ref_processor_stw()->enable_discovery();
1557 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1558
1559 // Do collection work
1560 {
1561 HandleMark hm; // Discard invalid handles created during gc
1562 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1563 }
1564
1565 assert(num_free_regions() == 0, "we should not have added any free regions");
1566 rebuild_region_sets(false /* free_list_only */);
1567
1568 // Enqueue any discovered reference objects that have
1569 // not been removed from the discovered lists.
1570 ref_processor_stw()->enqueue_discovered_references();
1571
1572 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1573
1574 MemoryService::track_memory_usage();
1575
1576 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1577 ref_processor_stw()->verify_no_references_recorded();
1578
1579 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1580 ClassLoaderDataGraph::purge();
1581 MetaspaceAux::verify_metrics();
1582
1583 // Note: since we've just done a full GC, concurrent
1584 // marking is no longer active. Therefore we need not
1585 // re-enable reference discovery for the CM ref processor.
1586 // That will be done at the start of the next marking cycle.
1587 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1588 ref_processor_cm()->verify_no_references_recorded();
1589
1590 reset_gc_time_stamp();
1591 // Since everything potentially moved, we will clear all remembered
1592 // sets, and clear all cards. Later we will rebuild remembered
1593 // sets. We will also reset the GC time stamps of the regions.
1594 clear_rsets_post_compaction();
1595 check_gc_time_stamps();
1596
1597 // Resize the heap if necessary.
1598 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1599
1600 if (_hr_printer.is_active()) {
1601 // We should do this after we potentially resize the heap so
1602 // that all the COMMIT / UNCOMMIT events are generated before
1603 // the end GC event.
1604
1605 print_hrm_post_compaction();
1606 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1607 }
1608
1609 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1610 if (hot_card_cache->use_cache()) {
1611 hot_card_cache->reset_card_counts();
1612 hot_card_cache->reset_hot_cache();
1613 }
1614
1615 // Rebuild remembered sets of all regions.
1616 uint n_workers =
1617 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1618 workers()->active_workers(),
1619 Threads::number_of_non_daemon_threads());
1620 workers()->set_active_workers(n_workers);
1621
1622 ParRebuildRSTask rebuild_rs_task(this);
1623 workers()->run_task(&rebuild_rs_task);
1624
1625 // Rebuild the strong code root lists for each region
1626 rebuild_strong_code_roots();
1627
1628 if (true) { // FIXME
1629 MetaspaceGC::compute_new_size();
1630 }
1631
1632 #ifdef TRACESPINNING
1633 ParallelTaskTerminator::print_termination_counts();
1634 #endif
1635
1636 // Discard all rset updates
1637 JavaThread::dirty_card_queue_set().abandon_logs();
1638 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1639
1640 _young_list->reset_sampled_info();
1641 // At this point there should be no regions in the
1642 // entire heap tagged as young.
1643 assert(check_young_list_empty(true /* check_heap */),
1644 "young list should be empty at this point");
1645
1646 // Update the number of full collections that have been completed.
1647 increment_old_marking_cycles_completed(false /* concurrent */);
1648
1649 _hrm.verify_optional();
1650 verify_region_sets_optional();
1651
1652 verify_after_gc();
1653
1654 // Clear the previous marking bitmap, if needed for bitmap verification.
1655 // Note we cannot do this when we clear the next marking bitmap in
1656 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1657 // objects marked during a full GC against the previous bitmap.
1658 // But we need to clear it before calling check_bitmaps below since
1659 // the full GC has compacted objects and updated TAMS but not updated
1660 // the prev bitmap.
1661 if (G1VerifyBitmaps) {
1662 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1663 }
1664 check_bitmaps("Full GC End");
1665
1666 // Start a new incremental collection set for the next pause
1667 assert(g1_policy()->collection_set() == NULL, "must be");
1668 g1_policy()->start_incremental_cset_building();
1669
1670 clear_cset_fast_test();
1671
1672 _allocator->init_mutator_alloc_region();
1673
1674 g1_policy()->record_full_collection_end();
1675
1676 if (G1Log::fine()) {
1677 g1_policy()->print_heap_transition();
1678 }
1679
1680 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1681 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1682 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1683 // before any GC notifications are raised.
1684 g1mm()->update_sizes();
1685
1686 gc_epilogue(true);
1687 }
1688
1689 if (G1Log::finer()) {
1690 g1_policy()->print_detailed_heap_transition(true /* full */);
1691 }
1692
1693 print_heap_after_gc();
1694 trace_heap_after_gc(gc_tracer);
1695
1696 post_full_gc_dump(gc_timer);
1697
1698 gc_timer->register_gc_end();
1699 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1700 }
1701
1702 return true;
1703 }
1704
1705 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1706 // do_collection() will return whether it succeeded in performing
1707 // the GC. Currently, there is no facility on the
1708 // do_full_collection() API to notify the caller than the collection
1709 // did not succeed (e.g., because it was locked out by the GC
1710 // locker). So, right now, we'll ignore the return value.
1711 bool dummy = do_collection(true, /* explicit_gc */
1712 clear_all_soft_refs,
1713 0 /* word_size */);
1714 }
1715
1716 // This code is mostly copied from TenuredGeneration.
1717 void
1718 G1CollectedHeap::
1719 resize_if_necessary_after_full_collection(size_t word_size) {
1720 // Include the current allocation, if any, and bytes that will be
1721 // pre-allocated to support collections, as "used".
1722 const size_t used_after_gc = used();
1723 const size_t capacity_after_gc = capacity();
1724 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1725
1726 // This is enforced in arguments.cpp.
1727 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1728 "otherwise the code below doesn't make sense");
1729
1730 // We don't have floating point command-line arguments
1731 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1732 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1733 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1734 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1735
1736 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1737 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1738
1739 // We have to be careful here as these two calculations can overflow
1740 // 32-bit size_t's.
1741 double used_after_gc_d = (double) used_after_gc;
1742 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1743 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1744
1745 // Let's make sure that they are both under the max heap size, which
1746 // by default will make them fit into a size_t.
1747 double desired_capacity_upper_bound = (double) max_heap_size;
1748 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1749 desired_capacity_upper_bound);
1750 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1751 desired_capacity_upper_bound);
1752
1753 // We can now safely turn them into size_t's.
1754 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1755 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1756
1757 // This assert only makes sense here, before we adjust them
1758 // with respect to the min and max heap size.
1759 assert(minimum_desired_capacity <= maximum_desired_capacity,
1760 "minimum_desired_capacity = " SIZE_FORMAT ", "
1761 "maximum_desired_capacity = " SIZE_FORMAT,
1762 minimum_desired_capacity, maximum_desired_capacity);
1763
1764 // Should not be greater than the heap max size. No need to adjust
1765 // it with respect to the heap min size as it's a lower bound (i.e.,
1766 // we'll try to make the capacity larger than it, not smaller).
1767 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1768 // Should not be less than the heap min size. No need to adjust it
1769 // with respect to the heap max size as it's an upper bound (i.e.,
1770 // we'll try to make the capacity smaller than it, not greater).
1771 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1772
1773 if (capacity_after_gc < minimum_desired_capacity) {
1774 // Don't expand unless it's significant
1775 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1776 ergo_verbose4(ErgoHeapSizing,
1777 "attempt heap expansion",
1778 ergo_format_reason("capacity lower than "
1779 "min desired capacity after Full GC")
1780 ergo_format_byte("capacity")
1781 ergo_format_byte("occupancy")
1782 ergo_format_byte_perc("min desired capacity"),
1783 capacity_after_gc, used_after_gc,
1784 minimum_desired_capacity, (double) MinHeapFreeRatio);
1785 expand(expand_bytes);
1786
1787 // No expansion, now see if we want to shrink
1788 } else if (capacity_after_gc > maximum_desired_capacity) {
1789 // Capacity too large, compute shrinking size
1790 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1791 ergo_verbose4(ErgoHeapSizing,
1792 "attempt heap shrinking",
1793 ergo_format_reason("capacity higher than "
1794 "max desired capacity after Full GC")
1795 ergo_format_byte("capacity")
1796 ergo_format_byte("occupancy")
1797 ergo_format_byte_perc("max desired capacity"),
1798 capacity_after_gc, used_after_gc,
1799 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1800 shrink(shrink_bytes);
1801 }
1802 }
1803
1804 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1805 AllocationContext_t context,
1806 bool do_gc,
1807 bool clear_all_soft_refs,
1808 bool expect_null_mutator_alloc_region,
1809 bool* gc_succeeded) {
1810 *gc_succeeded = true;
1811 // Let's attempt the allocation first.
1812 HeapWord* result =
1813 attempt_allocation_at_safepoint(word_size,
1814 context,
1815 expect_null_mutator_alloc_region);
1816 if (result != NULL) {
1817 assert(*gc_succeeded, "sanity");
1818 return result;
1819 }
1820
1821 // In a G1 heap, we're supposed to keep allocation from failing by
1822 // incremental pauses. Therefore, at least for now, we'll favor
1823 // expansion over collection. (This might change in the future if we can
1824 // do something smarter than full collection to satisfy a failed alloc.)
1825 result = expand_and_allocate(word_size, context);
1826 if (result != NULL) {
1827 assert(*gc_succeeded, "sanity");
1828 return result;
1829 }
1830
1831 if (do_gc) {
1832 // Expansion didn't work, we'll try to do a Full GC.
1833 *gc_succeeded = do_collection(false, /* explicit_gc */
1834 clear_all_soft_refs,
1835 word_size);
1836 }
1837
1838 return NULL;
1839 }
1840
1841 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1842 AllocationContext_t context,
1843 bool* succeeded) {
1844 assert_at_safepoint(true /* should_be_vm_thread */);
1845
1846 // Attempts to allocate followed by Full GC.
1847 HeapWord* result =
1848 satisfy_failed_allocation_helper(word_size,
1849 context,
1850 true, /* do_gc */
1851 false, /* clear_all_soft_refs */
1852 false, /* expect_null_mutator_alloc_region */
1853 succeeded);
1854
1855 if (result != NULL || !*succeeded) {
1856 return result;
1857 }
1858
1859 // Attempts to allocate followed by Full GC that will collect all soft references.
1860 result = satisfy_failed_allocation_helper(word_size,
1861 context,
1862 true, /* do_gc */
1863 true, /* clear_all_soft_refs */
1864 true, /* expect_null_mutator_alloc_region */
1865 succeeded);
1866
1867 if (result != NULL || !*succeeded) {
1868 return result;
1869 }
1870
1871 // Attempts to allocate, no GC
1872 result = satisfy_failed_allocation_helper(word_size,
1873 context,
1874 false, /* do_gc */
1875 false, /* clear_all_soft_refs */
1876 true, /* expect_null_mutator_alloc_region */
1877 succeeded);
1878
1879 if (result != NULL) {
1880 assert(*succeeded, "sanity");
1881 return result;
1882 }
1883
1884 assert(!collector_policy()->should_clear_all_soft_refs(),
1885 "Flag should have been handled and cleared prior to this point");
1886
1887 // What else? We might try synchronous finalization later. If the total
1888 // space available is large enough for the allocation, then a more
1889 // complete compaction phase than we've tried so far might be
1890 // appropriate.
1891 assert(*succeeded, "sanity");
1892 return NULL;
1893 }
1894
1895 // Attempting to expand the heap sufficiently
1896 // to support an allocation of the given "word_size". If
1897 // successful, perform the allocation and return the address of the
1898 // allocated block, or else "NULL".
1899
1900 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1901 assert_at_safepoint(true /* should_be_vm_thread */);
1902
1903 verify_region_sets_optional();
1904
1905 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1906 ergo_verbose1(ErgoHeapSizing,
1907 "attempt heap expansion",
1908 ergo_format_reason("allocation request failed")
1909 ergo_format_byte("allocation request"),
1910 word_size * HeapWordSize);
1911 if (expand(expand_bytes)) {
1912 _hrm.verify_optional();
1913 verify_region_sets_optional();
1914 return attempt_allocation_at_safepoint(word_size,
1915 context,
1916 false /* expect_null_mutator_alloc_region */);
1917 }
1918 return NULL;
1919 }
1920
1921 bool G1CollectedHeap::expand(size_t expand_bytes) {
1922 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1923 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1924 HeapRegion::GrainBytes);
1925 ergo_verbose2(ErgoHeapSizing,
1926 "expand the heap",
1927 ergo_format_byte("requested expansion amount")
1928 ergo_format_byte("attempted expansion amount"),
1929 expand_bytes, aligned_expand_bytes);
1930
1931 if (is_maximal_no_gc()) {
1932 ergo_verbose0(ErgoHeapSizing,
1933 "did not expand the heap",
1934 ergo_format_reason("heap already fully expanded"));
1935 return false;
1936 }
1937
1938 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1939 assert(regions_to_expand > 0, "Must expand by at least one region");
1940
1941 uint expanded_by = _hrm.expand_by(regions_to_expand);
1942
1943 if (expanded_by > 0) {
1944 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1945 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1946 g1_policy()->record_new_heap_size(num_regions());
1947 } else {
1948 ergo_verbose0(ErgoHeapSizing,
1949 "did not expand the heap",
1950 ergo_format_reason("heap expansion operation failed"));
1951 // The expansion of the virtual storage space was unsuccessful.
1952 // Let's see if it was because we ran out of swap.
1953 if (G1ExitOnExpansionFailure &&
1954 _hrm.available() >= regions_to_expand) {
1955 // We had head room...
1956 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1957 }
1958 }
1959 return regions_to_expand > 0;
1960 }
1961
1962 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1963 size_t aligned_shrink_bytes =
1964 ReservedSpace::page_align_size_down(shrink_bytes);
1965 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1966 HeapRegion::GrainBytes);
1967 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1968
1969 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1970 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1971
1972 ergo_verbose3(ErgoHeapSizing,
1973 "shrink the heap",
1974 ergo_format_byte("requested shrinking amount")
1975 ergo_format_byte("aligned shrinking amount")
1976 ergo_format_byte("attempted shrinking amount"),
1977 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1978 if (num_regions_removed > 0) {
1979 g1_policy()->record_new_heap_size(num_regions());
1980 } else {
1981 ergo_verbose0(ErgoHeapSizing,
1982 "did not shrink the heap",
1983 ergo_format_reason("heap shrinking operation failed"));
1984 }
1985 }
1986
1987 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1988 verify_region_sets_optional();
1989
1990 // We should only reach here at the end of a Full GC which means we
1991 // should not not be holding to any GC alloc regions. The method
1992 // below will make sure of that and do any remaining clean up.
1993 _allocator->abandon_gc_alloc_regions();
1994
1995 // Instead of tearing down / rebuilding the free lists here, we
1996 // could instead use the remove_all_pending() method on free_list to
1997 // remove only the ones that we need to remove.
1998 tear_down_region_sets(true /* free_list_only */);
1999 shrink_helper(shrink_bytes);
2000 rebuild_region_sets(true /* free_list_only */);
2001
2002 _hrm.verify_optional();
2003 verify_region_sets_optional();
2004 }
2005
2006 // Public methods.
2007
2008 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
2009 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
2010 #endif // _MSC_VER
2011
2012
2013 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2014 CollectedHeap(),
2015 _g1_policy(policy_),
2016 _dirty_card_queue_set(false),
2017 _into_cset_dirty_card_queue_set(false),
2018 _is_alive_closure_cm(this),
2019 _is_alive_closure_stw(this),
2020 _ref_processor_cm(NULL),
2021 _ref_processor_stw(NULL),
2022 _bot_shared(NULL),
2023 _cg1r(NULL),
2024 _g1mm(NULL),
2025 _refine_cte_cl(NULL),
2026 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2027 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2028 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2029 _humongous_reclaim_candidates(),
2030 _has_humongous_reclaim_candidates(false),
2031 _archive_allocator(NULL),
2032 _free_regions_coming(false),
2033 _young_list(new YoungList(this)),
2034 _gc_time_stamp(0),
2035 _summary_bytes_used(0),
2036 _survivor_evac_stats(YoungPLABSize, PLABWeight),
2037 _old_evac_stats(OldPLABSize, PLABWeight),
2038 _expand_heap_after_alloc_failure(true),
2039 _old_marking_cycles_started(0),
2040 _old_marking_cycles_completed(0),
2041 _heap_summary_sent(false),
2042 _in_cset_fast_test(),
2043 _dirty_cards_region_list(NULL),
2044 _worker_cset_start_region(NULL),
2045 _worker_cset_start_region_time_stamp(NULL),
2046 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2047 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2048 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2049 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2050
2051 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2052 /* are_GC_task_threads */true,
2053 /* are_ConcurrentGC_threads */false);
2054 _workers->initialize_workers();
2055
2056 _allocator = G1Allocator::create_allocator(this);
2057 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2058
2059 // Override the default _filler_array_max_size so that no humongous filler
2060 // objects are created.
2061 _filler_array_max_size = _humongous_object_threshold_in_words;
2062
2063 uint n_queues = ParallelGCThreads;
2064 _task_queues = new RefToScanQueueSet(n_queues);
2065
2066 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2067 assert(n_rem_sets > 0, "Invariant.");
2068
2069 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2070 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2071 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2072
2073 for (uint i = 0; i < n_queues; i++) {
2074 RefToScanQueue* q = new RefToScanQueue();
2075 q->initialize();
2076 _task_queues->register_queue(i, q);
2077 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2078 }
2079 clear_cset_start_regions();
2080
2081 // Initialize the G1EvacuationFailureALot counters and flags.
2082 NOT_PRODUCT(reset_evacuation_should_fail();)
2083
2084 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2085 }
2086
2087 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2088 size_t size,
2089 size_t translation_factor) {
2090 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2091 // Allocate a new reserved space, preferring to use large pages.
2092 ReservedSpace rs(size, preferred_page_size);
2093 G1RegionToSpaceMapper* result =
2094 G1RegionToSpaceMapper::create_mapper(rs,
2095 size,
2096 rs.alignment(),
2097 HeapRegion::GrainBytes,
2098 translation_factor,
2099 mtGC);
2100 if (TracePageSizes) {
2101 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2102 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2103 }
2104 return result;
2105 }
2106
2107 jint G1CollectedHeap::initialize() {
2108 CollectedHeap::pre_initialize();
2109 os::enable_vtime();
2110
2111 G1Log::init();
2112
2113 // Necessary to satisfy locking discipline assertions.
2114
2115 MutexLocker x(Heap_lock);
2116
2117 // We have to initialize the printer before committing the heap, as
2118 // it will be used then.
2119 _hr_printer.set_active(G1PrintHeapRegions);
2120
2121 // While there are no constraints in the GC code that HeapWordSize
2122 // be any particular value, there are multiple other areas in the
2123 // system which believe this to be true (e.g. oop->object_size in some
2124 // cases incorrectly returns the size in wordSize units rather than
2125 // HeapWordSize).
2126 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2127
2128 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2129 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2130 size_t heap_alignment = collector_policy()->heap_alignment();
2131
2132 // Ensure that the sizes are properly aligned.
2133 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2134 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2135 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2136
2137 _refine_cte_cl = new RefineCardTableEntryClosure();
2138
2139 jint ecode = JNI_OK;
2140 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
2141 if (_cg1r == NULL) {
2142 return ecode;
2143 }
2144
2145 // Reserve the maximum.
2146
2147 // When compressed oops are enabled, the preferred heap base
2148 // is calculated by subtracting the requested size from the
2149 // 32Gb boundary and using the result as the base address for
2150 // heap reservation. If the requested size is not aligned to
2151 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2152 // into the ReservedHeapSpace constructor) then the actual
2153 // base of the reserved heap may end up differing from the
2154 // address that was requested (i.e. the preferred heap base).
2155 // If this happens then we could end up using a non-optimal
2156 // compressed oops mode.
2157
2158 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2159 heap_alignment);
2160
2161 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2162
2163 // Create the barrier set for the entire reserved region.
2164 G1SATBCardTableLoggingModRefBS* bs
2165 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2166 bs->initialize();
2167 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2168 set_barrier_set(bs);
2169
2170 // Also create a G1 rem set.
2171 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2172
2173 // Carve out the G1 part of the heap.
2174
2175 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2176 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2177 G1RegionToSpaceMapper* heap_storage =
2178 G1RegionToSpaceMapper::create_mapper(g1_rs,
2179 g1_rs.size(),
2180 page_size,
2181 HeapRegion::GrainBytes,
2182 1,
2183 mtJavaHeap);
2184 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2185 max_byte_size, page_size,
2186 heap_rs.base(),
2187 heap_rs.size());
2188 heap_storage->set_mapping_changed_listener(&_listener);
2189
2190 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2191 G1RegionToSpaceMapper* bot_storage =
2192 create_aux_memory_mapper("Block offset table",
2193 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2194 G1BlockOffsetSharedArray::heap_map_factor());
2195
2196 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2197 G1RegionToSpaceMapper* cardtable_storage =
2198 create_aux_memory_mapper("Card table",
2199 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2200 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2201
2202 G1RegionToSpaceMapper* card_counts_storage =
2203 create_aux_memory_mapper("Card counts table",
2204 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2205 G1CardCounts::heap_map_factor());
2206
2207 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2208 G1RegionToSpaceMapper* prev_bitmap_storage =
2209 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2210 G1RegionToSpaceMapper* next_bitmap_storage =
2211 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2212
2213 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2214 g1_barrier_set()->initialize(cardtable_storage);
2215 // Do later initialization work for concurrent refinement.
2216 _cg1r->init(card_counts_storage);
2217
2218 // 6843694 - ensure that the maximum region index can fit
2219 // in the remembered set structures.
2220 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2221 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2222
2223 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2224 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2225 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2226 "too many cards per region");
2227
2228 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2229
2230 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2231
2232 {
2233 HeapWord* start = _hrm.reserved().start();
2234 HeapWord* end = _hrm.reserved().end();
2235 size_t granularity = HeapRegion::GrainBytes;
2236
2237 _in_cset_fast_test.initialize(start, end, granularity);
2238 _humongous_reclaim_candidates.initialize(start, end, granularity);
2239 }
2240
2241 // Create the ConcurrentMark data structure and thread.
2242 // (Must do this late, so that "max_regions" is defined.)
2243 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2244 if (_cm == NULL || !_cm->completed_initialization()) {
2245 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2246 return JNI_ENOMEM;
2247 }
2248 _cmThread = _cm->cmThread();
2249
2250 // Initialize the from_card cache structure of HeapRegionRemSet.
2251 HeapRegionRemSet::init_heap(max_regions());
2252
2253 // Now expand into the initial heap size.
2254 if (!expand(init_byte_size)) {
2255 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2256 return JNI_ENOMEM;
2257 }
2258
2259 // Perform any initialization actions delegated to the policy.
2260 g1_policy()->init();
2261
2262 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2263 SATB_Q_FL_lock,
2264 G1SATBProcessCompletedThreshold,
2265 Shared_SATB_Q_lock);
2266
2267 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2268 DirtyCardQ_CBL_mon,
2269 DirtyCardQ_FL_lock,
2270 concurrent_g1_refine()->yellow_zone(),
2271 concurrent_g1_refine()->red_zone(),
2272 Shared_DirtyCardQ_lock);
2273
2274 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2275 DirtyCardQ_CBL_mon,
2276 DirtyCardQ_FL_lock,
2277 -1, // never trigger processing
2278 -1, // no limit on length
2279 Shared_DirtyCardQ_lock,
2280 &JavaThread::dirty_card_queue_set());
2281
2282 // Initialize the card queue set used to hold cards containing
2283 // references into the collection set.
2284 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2285 DirtyCardQ_CBL_mon,
2286 DirtyCardQ_FL_lock,
2287 -1, // never trigger processing
2288 -1, // no limit on length
2289 Shared_DirtyCardQ_lock,
2290 &JavaThread::dirty_card_queue_set());
2291
2292 // Here we allocate the dummy HeapRegion that is required by the
2293 // G1AllocRegion class.
2294 HeapRegion* dummy_region = _hrm.get_dummy_region();
2295
2296 // We'll re-use the same region whether the alloc region will
2297 // require BOT updates or not and, if it doesn't, then a non-young
2298 // region will complain that it cannot support allocations without
2299 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2300 dummy_region->set_eden();
2301 // Make sure it's full.
2302 dummy_region->set_top(dummy_region->end());
2303 G1AllocRegion::setup(this, dummy_region);
2304
2305 _allocator->init_mutator_alloc_region();
2306
2307 // Do create of the monitoring and management support so that
2308 // values in the heap have been properly initialized.
2309 _g1mm = new G1MonitoringSupport(this);
2310
2311 G1StringDedup::initialize();
2312
2313 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2314 for (uint i = 0; i < ParallelGCThreads; i++) {
2315 new (&_preserved_objs[i]) OopAndMarkOopStack();
2316 }
2317
2318 return JNI_OK;
2319 }
2320
2321 void G1CollectedHeap::stop() {
2322 // Stop all concurrent threads. We do this to make sure these threads
2323 // do not continue to execute and access resources (e.g. gclog_or_tty)
2324 // that are destroyed during shutdown.
2325 _cg1r->stop();
2326 _cmThread->stop();
2327 if (G1StringDedup::is_enabled()) {
2328 G1StringDedup::stop();
2329 }
2330 }
2331
2332 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2333 return HeapRegion::max_region_size();
2334 }
2335
2336 void G1CollectedHeap::post_initialize() {
2337 CollectedHeap::post_initialize();
2338 ref_processing_init();
2339 }
2340
2341 void G1CollectedHeap::ref_processing_init() {
2342 // Reference processing in G1 currently works as follows:
2343 //
2344 // * There are two reference processor instances. One is
2345 // used to record and process discovered references
2346 // during concurrent marking; the other is used to
2347 // record and process references during STW pauses
2348 // (both full and incremental).
2349 // * Both ref processors need to 'span' the entire heap as
2350 // the regions in the collection set may be dotted around.
2351 //
2352 // * For the concurrent marking ref processor:
2353 // * Reference discovery is enabled at initial marking.
2354 // * Reference discovery is disabled and the discovered
2355 // references processed etc during remarking.
2356 // * Reference discovery is MT (see below).
2357 // * Reference discovery requires a barrier (see below).
2358 // * Reference processing may or may not be MT
2359 // (depending on the value of ParallelRefProcEnabled
2360 // and ParallelGCThreads).
2361 // * A full GC disables reference discovery by the CM
2362 // ref processor and abandons any entries on it's
2363 // discovered lists.
2364 //
2365 // * For the STW processor:
2366 // * Non MT discovery is enabled at the start of a full GC.
2367 // * Processing and enqueueing during a full GC is non-MT.
2368 // * During a full GC, references are processed after marking.
2369 //
2370 // * Discovery (may or may not be MT) is enabled at the start
2371 // of an incremental evacuation pause.
2372 // * References are processed near the end of a STW evacuation pause.
2373 // * For both types of GC:
2374 // * Discovery is atomic - i.e. not concurrent.
2375 // * Reference discovery will not need a barrier.
2376
2377 MemRegion mr = reserved_region();
2378
2379 // Concurrent Mark ref processor
2380 _ref_processor_cm =
2381 new ReferenceProcessor(mr, // span
2382 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2383 // mt processing
2384 ParallelGCThreads,
2385 // degree of mt processing
2386 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2387 // mt discovery
2388 MAX2(ParallelGCThreads, ConcGCThreads),
2389 // degree of mt discovery
2390 false,
2391 // Reference discovery is not atomic
2392 &_is_alive_closure_cm);
2393 // is alive closure
2394 // (for efficiency/performance)
2395
2396 // STW ref processor
2397 _ref_processor_stw =
2398 new ReferenceProcessor(mr, // span
2399 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2400 // mt processing
2401 ParallelGCThreads,
2402 // degree of mt processing
2403 (ParallelGCThreads > 1),
2404 // mt discovery
2405 ParallelGCThreads,
2406 // degree of mt discovery
2407 true,
2408 // Reference discovery is atomic
2409 &_is_alive_closure_stw);
2410 // is alive closure
2411 // (for efficiency/performance)
2412 }
2413
2414 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2415 return g1_policy();
2416 }
2417
2418 size_t G1CollectedHeap::capacity() const {
2419 return _hrm.length() * HeapRegion::GrainBytes;
2420 }
2421
2422 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2423 assert(!hr->is_continues_humongous(), "pre-condition");
2424 hr->reset_gc_time_stamp();
2425 if (hr->is_starts_humongous()) {
2426 uint first_index = hr->hrm_index() + 1;
2427 uint last_index = hr->last_hc_index();
2428 for (uint i = first_index; i < last_index; i += 1) {
2429 HeapRegion* chr = region_at(i);
2430 assert(chr->is_continues_humongous(), "sanity");
2431 chr->reset_gc_time_stamp();
2432 }
2433 }
2434 }
2435
2436 #ifndef PRODUCT
2437
2438 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2439 private:
2440 unsigned _gc_time_stamp;
2441 bool _failures;
2442
2443 public:
2444 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2445 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2446
2447 virtual bool doHeapRegion(HeapRegion* hr) {
2448 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2449 if (_gc_time_stamp != region_gc_time_stamp) {
2450 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2451 "expected %d", HR_FORMAT_PARAMS(hr),
2452 region_gc_time_stamp, _gc_time_stamp);
2453 _failures = true;
2454 }
2455 return false;
2456 }
2457
2458 bool failures() { return _failures; }
2459 };
2460
2461 void G1CollectedHeap::check_gc_time_stamps() {
2462 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2463 heap_region_iterate(&cl);
2464 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2465 }
2466 #endif // PRODUCT
2467
2468 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2469 DirtyCardQueue* into_cset_dcq,
2470 bool concurrent,
2471 uint worker_i) {
2472 // Clean cards in the hot card cache
2473 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2474 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2475
2476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2477 size_t n_completed_buffers = 0;
2478 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2479 n_completed_buffers++;
2480 }
2481 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2482 dcqs.clear_n_completed_buffers();
2483 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2484 }
2485
2486 // Computes the sum of the storage used by the various regions.
2487 size_t G1CollectedHeap::used() const {
2488 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2489 if (_archive_allocator != NULL) {
2490 result += _archive_allocator->used();
2491 }
2492 return result;
2493 }
2494
2495 size_t G1CollectedHeap::used_unlocked() const {
2496 return _summary_bytes_used;
2497 }
2498
2499 class SumUsedClosure: public HeapRegionClosure {
2500 size_t _used;
2501 public:
2502 SumUsedClosure() : _used(0) {}
2503 bool doHeapRegion(HeapRegion* r) {
2504 if (!r->is_continues_humongous()) {
2505 _used += r->used();
2506 }
2507 return false;
2508 }
2509 size_t result() { return _used; }
2510 };
2511
2512 size_t G1CollectedHeap::recalculate_used() const {
2513 double recalculate_used_start = os::elapsedTime();
2514
2515 SumUsedClosure blk;
2516 heap_region_iterate(&blk);
2517
2518 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2519 return blk.result();
2520 }
2521
2522 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2523 switch (cause) {
2524 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2525 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2526 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2527 case GCCause::_g1_humongous_allocation: return true;
2528 case GCCause::_update_allocation_context_stats_inc: return true;
2529 case GCCause::_wb_conc_mark: return true;
2530 default: return false;
2531 }
2532 }
2533
2534 #ifndef PRODUCT
2535 void G1CollectedHeap::allocate_dummy_regions() {
2536 // Let's fill up most of the region
2537 size_t word_size = HeapRegion::GrainWords - 1024;
2538 // And as a result the region we'll allocate will be humongous.
2539 guarantee(is_humongous(word_size), "sanity");
2540
2541 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2542 // Let's use the existing mechanism for the allocation
2543 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2544 AllocationContext::system());
2545 if (dummy_obj != NULL) {
2546 MemRegion mr(dummy_obj, word_size);
2547 CollectedHeap::fill_with_object(mr);
2548 } else {
2549 // If we can't allocate once, we probably cannot allocate
2550 // again. Let's get out of the loop.
2551 break;
2552 }
2553 }
2554 }
2555 #endif // !PRODUCT
2556
2557 void G1CollectedHeap::increment_old_marking_cycles_started() {
2558 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2559 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2560 "Wrong marking cycle count (started: %d, completed: %d)",
2561 _old_marking_cycles_started, _old_marking_cycles_completed);
2562
2563 _old_marking_cycles_started++;
2564 }
2565
2566 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2567 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2568
2569 // We assume that if concurrent == true, then the caller is a
2570 // concurrent thread that was joined the Suspendible Thread
2571 // Set. If there's ever a cheap way to check this, we should add an
2572 // assert here.
2573
2574 // Given that this method is called at the end of a Full GC or of a
2575 // concurrent cycle, and those can be nested (i.e., a Full GC can
2576 // interrupt a concurrent cycle), the number of full collections
2577 // completed should be either one (in the case where there was no
2578 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2579 // behind the number of full collections started.
2580
2581 // This is the case for the inner caller, i.e. a Full GC.
2582 assert(concurrent ||
2583 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2584 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2585 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2586 "is inconsistent with _old_marking_cycles_completed = %u",
2587 _old_marking_cycles_started, _old_marking_cycles_completed);
2588
2589 // This is the case for the outer caller, i.e. the concurrent cycle.
2590 assert(!concurrent ||
2591 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2592 "for outer caller (concurrent cycle): "
2593 "_old_marking_cycles_started = %u "
2594 "is inconsistent with _old_marking_cycles_completed = %u",
2595 _old_marking_cycles_started, _old_marking_cycles_completed);
2596
2597 _old_marking_cycles_completed += 1;
2598
2599 // We need to clear the "in_progress" flag in the CM thread before
2600 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2601 // is set) so that if a waiter requests another System.gc() it doesn't
2602 // incorrectly see that a marking cycle is still in progress.
2603 if (concurrent) {
2604 _cmThread->set_idle();
2605 }
2606
2607 // This notify_all() will ensure that a thread that called
2608 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2609 // and it's waiting for a full GC to finish will be woken up. It is
2610 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2611 FullGCCount_lock->notify_all();
2612 }
2613
2614 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2615 GCIdMarkAndRestore conc_gc_id_mark;
2616 collector_state()->set_concurrent_cycle_started(true);
2617 _gc_timer_cm->register_gc_start(start_time);
2618
2619 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2620 trace_heap_before_gc(_gc_tracer_cm);
2621 _cmThread->set_gc_id(GCId::current());
2622 }
2623
2624 void G1CollectedHeap::register_concurrent_cycle_end() {
2625 if (collector_state()->concurrent_cycle_started()) {
2626 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2627 if (_cm->has_aborted()) {
2628 _gc_tracer_cm->report_concurrent_mode_failure();
2629 }
2630
2631 _gc_timer_cm->register_gc_end();
2632 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2633
2634 // Clear state variables to prepare for the next concurrent cycle.
2635 collector_state()->set_concurrent_cycle_started(false);
2636 _heap_summary_sent = false;
2637 }
2638 }
2639
2640 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2641 if (collector_state()->concurrent_cycle_started()) {
2642 // This function can be called when:
2643 // the cleanup pause is run
2644 // the concurrent cycle is aborted before the cleanup pause.
2645 // the concurrent cycle is aborted after the cleanup pause,
2646 // but before the concurrent cycle end has been registered.
2647 // Make sure that we only send the heap information once.
2648 if (!_heap_summary_sent) {
2649 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2650 trace_heap_after_gc(_gc_tracer_cm);
2651 _heap_summary_sent = true;
2652 }
2653 }
2654 }
2655
2656 void G1CollectedHeap::collect(GCCause::Cause cause) {
2657 assert_heap_not_locked();
2658
2659 uint gc_count_before;
2660 uint old_marking_count_before;
2661 uint full_gc_count_before;
2662 bool retry_gc;
2663
2664 do {
2665 retry_gc = false;
2666
2667 {
2668 MutexLocker ml(Heap_lock);
2669
2670 // Read the GC count while holding the Heap_lock
2671 gc_count_before = total_collections();
2672 full_gc_count_before = total_full_collections();
2673 old_marking_count_before = _old_marking_cycles_started;
2674 }
2675
2676 if (should_do_concurrent_full_gc(cause)) {
2677 // Schedule an initial-mark evacuation pause that will start a
2678 // concurrent cycle. We're setting word_size to 0 which means that
2679 // we are not requesting a post-GC allocation.
2680 VM_G1IncCollectionPause op(gc_count_before,
2681 0, /* word_size */
2682 true, /* should_initiate_conc_mark */
2683 g1_policy()->max_pause_time_ms(),
2684 cause);
2685 op.set_allocation_context(AllocationContext::current());
2686
2687 VMThread::execute(&op);
2688 if (!op.pause_succeeded()) {
2689 if (old_marking_count_before == _old_marking_cycles_started) {
2690 retry_gc = op.should_retry_gc();
2691 } else {
2692 // A Full GC happened while we were trying to schedule the
2693 // initial-mark GC. No point in starting a new cycle given
2694 // that the whole heap was collected anyway.
2695 }
2696
2697 if (retry_gc) {
2698 if (GC_locker::is_active_and_needs_gc()) {
2699 GC_locker::stall_until_clear();
2700 }
2701 }
2702 }
2703 } else {
2704 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2705 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2706
2707 // Schedule a standard evacuation pause. We're setting word_size
2708 // to 0 which means that we are not requesting a post-GC allocation.
2709 VM_G1IncCollectionPause op(gc_count_before,
2710 0, /* word_size */
2711 false, /* should_initiate_conc_mark */
2712 g1_policy()->max_pause_time_ms(),
2713 cause);
2714 VMThread::execute(&op);
2715 } else {
2716 // Schedule a Full GC.
2717 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2718 VMThread::execute(&op);
2719 }
2720 }
2721 } while (retry_gc);
2722 }
2723
2724 bool G1CollectedHeap::is_in(const void* p) const {
2725 if (_hrm.reserved().contains(p)) {
2726 // Given that we know that p is in the reserved space,
2727 // heap_region_containing_raw() should successfully
2728 // return the containing region.
2729 HeapRegion* hr = heap_region_containing_raw(p);
2730 return hr->is_in(p);
2731 } else {
2732 return false;
2733 }
2734 }
2735
2736 #ifdef ASSERT
2737 bool G1CollectedHeap::is_in_exact(const void* p) const {
2738 bool contains = reserved_region().contains(p);
2739 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2740 if (contains && available) {
2741 return true;
2742 } else {
2743 return false;
2744 }
2745 }
2746 #endif
2747
2748 bool G1CollectedHeap::obj_in_cs(oop obj) {
2749 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2750 return r != NULL && r->in_collection_set();
2751 }
2752
2753 // Iteration functions.
2754
2755 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2756
2757 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2758 ExtendedOopClosure* _cl;
2759 public:
2760 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2761 bool doHeapRegion(HeapRegion* r) {
2762 if (!r->is_continues_humongous()) {
2763 r->oop_iterate(_cl);
2764 }
2765 return false;
2766 }
2767 };
2768
2769 // Iterates an ObjectClosure over all objects within a HeapRegion.
2770
2771 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2772 ObjectClosure* _cl;
2773 public:
2774 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2775 bool doHeapRegion(HeapRegion* r) {
2776 if (!r->is_continues_humongous()) {
2777 r->object_iterate(_cl);
2778 }
2779 return false;
2780 }
2781 };
2782
2783 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2784 IterateObjectClosureRegionClosure blk(cl);
2785 heap_region_iterate(&blk);
2786 }
2787
2788 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2789 _hrm.iterate(cl);
2790 }
2791
2792 void
2793 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2794 uint worker_id,
2795 HeapRegionClaimer *hrclaimer,
2796 bool concurrent) const {
2797 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2798 }
2799
2800 // Clear the cached CSet starting regions and (more importantly)
2801 // the time stamps. Called when we reset the GC time stamp.
2802 void G1CollectedHeap::clear_cset_start_regions() {
2803 assert(_worker_cset_start_region != NULL, "sanity");
2804 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2805
2806 for (uint i = 0; i < ParallelGCThreads; i++) {
2807 _worker_cset_start_region[i] = NULL;
2808 _worker_cset_start_region_time_stamp[i] = 0;
2809 }
2810 }
2811
2812 // Given the id of a worker, obtain or calculate a suitable
2813 // starting region for iterating over the current collection set.
2814 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2815 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2816
2817 HeapRegion* result = NULL;
2818 unsigned gc_time_stamp = get_gc_time_stamp();
2819
2820 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2821 // Cached starting region for current worker was set
2822 // during the current pause - so it's valid.
2823 // Note: the cached starting heap region may be NULL
2824 // (when the collection set is empty).
2825 result = _worker_cset_start_region[worker_i];
2826 assert(result == NULL || result->in_collection_set(), "sanity");
2827 return result;
2828 }
2829
2830 // The cached entry was not valid so let's calculate
2831 // a suitable starting heap region for this worker.
2832
2833 // We want the parallel threads to start their collection
2834 // set iteration at different collection set regions to
2835 // avoid contention.
2836 // If we have:
2837 // n collection set regions
2838 // p threads
2839 // Then thread t will start at region floor ((t * n) / p)
2840
2841 result = g1_policy()->collection_set();
2842 uint cs_size = g1_policy()->cset_region_length();
2843 uint active_workers = workers()->active_workers();
2844
2845 uint end_ind = (cs_size * worker_i) / active_workers;
2846 uint start_ind = 0;
2847
2848 if (worker_i > 0 &&
2849 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2850 // Previous workers starting region is valid
2851 // so let's iterate from there
2852 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2853 result = _worker_cset_start_region[worker_i - 1];
2854 }
2855
2856 for (uint i = start_ind; i < end_ind; i++) {
2857 result = result->next_in_collection_set();
2858 }
2859
2860 // Note: the calculated starting heap region may be NULL
2861 // (when the collection set is empty).
2862 assert(result == NULL || result->in_collection_set(), "sanity");
2863 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2864 "should be updated only once per pause");
2865 _worker_cset_start_region[worker_i] = result;
2866 OrderAccess::storestore();
2867 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2868 return result;
2869 }
2870
2871 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2872 HeapRegion* r = g1_policy()->collection_set();
2873 while (r != NULL) {
2874 HeapRegion* next = r->next_in_collection_set();
2875 if (cl->doHeapRegion(r)) {
2876 cl->incomplete();
2877 return;
2878 }
2879 r = next;
2880 }
2881 }
2882
2883 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2884 HeapRegionClosure *cl) {
2885 if (r == NULL) {
2886 // The CSet is empty so there's nothing to do.
2887 return;
2888 }
2889
2890 assert(r->in_collection_set(),
2891 "Start region must be a member of the collection set.");
2892 HeapRegion* cur = r;
2893 while (cur != NULL) {
2894 HeapRegion* next = cur->next_in_collection_set();
2895 if (cl->doHeapRegion(cur) && false) {
2896 cl->incomplete();
2897 return;
2898 }
2899 cur = next;
2900 }
2901 cur = g1_policy()->collection_set();
2902 while (cur != r) {
2903 HeapRegion* next = cur->next_in_collection_set();
2904 if (cl->doHeapRegion(cur) && false) {
2905 cl->incomplete();
2906 return;
2907 }
2908 cur = next;
2909 }
2910 }
2911
2912 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2913 HeapRegion* result = _hrm.next_region_in_heap(from);
2914 while (result != NULL && result->is_pinned()) {
2915 result = _hrm.next_region_in_heap(result);
2916 }
2917 return result;
2918 }
2919
2920 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2921 HeapRegion* hr = heap_region_containing(addr);
2922 return hr->block_start(addr);
2923 }
2924
2925 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2926 HeapRegion* hr = heap_region_containing(addr);
2927 return hr->block_size(addr);
2928 }
2929
2930 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2931 HeapRegion* hr = heap_region_containing(addr);
2932 return hr->block_is_obj(addr);
2933 }
2934
2935 bool G1CollectedHeap::supports_tlab_allocation() const {
2936 return true;
2937 }
2938
2939 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2940 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2941 }
2942
2943 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2944 return young_list()->eden_used_bytes();
2945 }
2946
2947 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2948 // must be equal to the humongous object limit.
2949 size_t G1CollectedHeap::max_tlab_size() const {
2950 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2951 }
2952
2953 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2954 AllocationContext_t context = AllocationContext::current();
2955 return _allocator->unsafe_max_tlab_alloc(context);
2956 }
2957
2958 size_t G1CollectedHeap::max_capacity() const {
2959 return _hrm.reserved().byte_size();
2960 }
2961
2962 jlong G1CollectedHeap::millis_since_last_gc() {
2963 // assert(false, "NYI");
2964 return 0;
2965 }
2966
2967 void G1CollectedHeap::prepare_for_verify() {
2968 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2969 ensure_parsability(false);
2970 }
2971 g1_rem_set()->prepare_for_verify();
2972 }
2973
2974 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2975 VerifyOption vo) {
2976 switch (vo) {
2977 case VerifyOption_G1UsePrevMarking:
2978 return hr->obj_allocated_since_prev_marking(obj);
2979 case VerifyOption_G1UseNextMarking:
2980 return hr->obj_allocated_since_next_marking(obj);
2981 case VerifyOption_G1UseMarkWord:
2982 return false;
2983 default:
2984 ShouldNotReachHere();
2985 }
2986 return false; // keep some compilers happy
2987 }
2988
2989 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2990 switch (vo) {
2991 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2992 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2993 case VerifyOption_G1UseMarkWord: return NULL;
2994 default: ShouldNotReachHere();
2995 }
2996 return NULL; // keep some compilers happy
2997 }
2998
2999 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3000 switch (vo) {
3001 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3002 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3003 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3004 default: ShouldNotReachHere();
3005 }
3006 return false; // keep some compilers happy
3007 }
3008
3009 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3010 switch (vo) {
3011 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3012 case VerifyOption_G1UseNextMarking: return "NTAMS";
3013 case VerifyOption_G1UseMarkWord: return "NONE";
3014 default: ShouldNotReachHere();
3015 }
3016 return NULL; // keep some compilers happy
3017 }
3018
3019 class VerifyRootsClosure: public OopClosure {
3020 private:
3021 G1CollectedHeap* _g1h;
3022 VerifyOption _vo;
3023 bool _failures;
3024 public:
3025 // _vo == UsePrevMarking -> use "prev" marking information,
3026 // _vo == UseNextMarking -> use "next" marking information,
3027 // _vo == UseMarkWord -> use mark word from object header.
3028 VerifyRootsClosure(VerifyOption vo) :
3029 _g1h(G1CollectedHeap::heap()),
3030 _vo(vo),
3031 _failures(false) { }
3032
3033 bool failures() { return _failures; }
3034
3035 template <class T> void do_oop_nv(T* p) {
3036 T heap_oop = oopDesc::load_heap_oop(p);
3037 if (!oopDesc::is_null(heap_oop)) {
3038 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3039 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3040 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3041 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3042 if (_vo == VerifyOption_G1UseMarkWord) {
3043 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3044 }
3045 obj->print_on(gclog_or_tty);
3046 _failures = true;
3047 }
3048 }
3049 }
3050
3051 void do_oop(oop* p) { do_oop_nv(p); }
3052 void do_oop(narrowOop* p) { do_oop_nv(p); }
3053 };
3054
3055 class G1VerifyCodeRootOopClosure: public OopClosure {
3056 G1CollectedHeap* _g1h;
3057 OopClosure* _root_cl;
3058 nmethod* _nm;
3059 VerifyOption _vo;
3060 bool _failures;
3061
3062 template <class T> void do_oop_work(T* p) {
3063 // First verify that this root is live
3064 _root_cl->do_oop(p);
3065
3066 if (!G1VerifyHeapRegionCodeRoots) {
3067 // We're not verifying the code roots attached to heap region.
3068 return;
3069 }
3070
3071 // Don't check the code roots during marking verification in a full GC
3072 if (_vo == VerifyOption_G1UseMarkWord) {
3073 return;
3074 }
3075
3076 // Now verify that the current nmethod (which contains p) is
3077 // in the code root list of the heap region containing the
3078 // object referenced by p.
3079
3080 T heap_oop = oopDesc::load_heap_oop(p);
3081 if (!oopDesc::is_null(heap_oop)) {
3082 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3083
3084 // Now fetch the region containing the object
3085 HeapRegion* hr = _g1h->heap_region_containing(obj);
3086 HeapRegionRemSet* hrrs = hr->rem_set();
3087 // Verify that the strong code root list for this region
3088 // contains the nmethod
3089 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3090 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3091 "from nmethod " PTR_FORMAT " not in strong "
3092 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3093 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3094 _failures = true;
3095 }
3096 }
3097 }
3098
3099 public:
3100 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3101 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3102
3103 void do_oop(oop* p) { do_oop_work(p); }
3104 void do_oop(narrowOop* p) { do_oop_work(p); }
3105
3106 void set_nmethod(nmethod* nm) { _nm = nm; }
3107 bool failures() { return _failures; }
3108 };
3109
3110 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3111 G1VerifyCodeRootOopClosure* _oop_cl;
3112
3113 public:
3114 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3115 _oop_cl(oop_cl) {}
3116
3117 void do_code_blob(CodeBlob* cb) {
3118 nmethod* nm = cb->as_nmethod_or_null();
3119 if (nm != NULL) {
3120 _oop_cl->set_nmethod(nm);
3121 nm->oops_do(_oop_cl);
3122 }
3123 }
3124 };
3125
3126 class YoungRefCounterClosure : public OopClosure {
3127 G1CollectedHeap* _g1h;
3128 int _count;
3129 public:
3130 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3131 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3132 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3133
3134 int count() { return _count; }
3135 void reset_count() { _count = 0; };
3136 };
3137
3138 class VerifyKlassClosure: public KlassClosure {
3139 YoungRefCounterClosure _young_ref_counter_closure;
3140 OopClosure *_oop_closure;
3141 public:
3142 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3143 void do_klass(Klass* k) {
3144 k->oops_do(_oop_closure);
3145
3146 _young_ref_counter_closure.reset_count();
3147 k->oops_do(&_young_ref_counter_closure);
3148 if (_young_ref_counter_closure.count() > 0) {
3149 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
3150 }
3151 }
3152 };
3153
3154 class VerifyLivenessOopClosure: public OopClosure {
3155 G1CollectedHeap* _g1h;
3156 VerifyOption _vo;
3157 public:
3158 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3159 _g1h(g1h), _vo(vo)
3160 { }
3161 void do_oop(narrowOop *p) { do_oop_work(p); }
3162 void do_oop( oop *p) { do_oop_work(p); }
3163
3164 template <class T> void do_oop_work(T *p) {
3165 oop obj = oopDesc::load_decode_heap_oop(p);
3166 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3167 "Dead object referenced by a not dead object");
3168 }
3169 };
3170
3171 class VerifyObjsInRegionClosure: public ObjectClosure {
3172 private:
3173 G1CollectedHeap* _g1h;
3174 size_t _live_bytes;
3175 HeapRegion *_hr;
3176 VerifyOption _vo;
3177 public:
3178 // _vo == UsePrevMarking -> use "prev" marking information,
3179 // _vo == UseNextMarking -> use "next" marking information,
3180 // _vo == UseMarkWord -> use mark word from object header.
3181 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3182 : _live_bytes(0), _hr(hr), _vo(vo) {
3183 _g1h = G1CollectedHeap::heap();
3184 }
3185 void do_object(oop o) {
3186 VerifyLivenessOopClosure isLive(_g1h, _vo);
3187 assert(o != NULL, "Huh?");
3188 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3189 // If the object is alive according to the mark word,
3190 // then verify that the marking information agrees.
3191 // Note we can't verify the contra-positive of the
3192 // above: if the object is dead (according to the mark
3193 // word), it may not be marked, or may have been marked
3194 // but has since became dead, or may have been allocated
3195 // since the last marking.
3196 if (_vo == VerifyOption_G1UseMarkWord) {
3197 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3198 }
3199
3200 o->oop_iterate_no_header(&isLive);
3201 if (!_hr->obj_allocated_since_prev_marking(o)) {
3202 size_t obj_size = o->size(); // Make sure we don't overflow
3203 _live_bytes += (obj_size * HeapWordSize);
3204 }
3205 }
3206 }
3207 size_t live_bytes() { return _live_bytes; }
3208 };
3209
3210 class VerifyArchiveOopClosure: public OopClosure {
3211 public:
3212 VerifyArchiveOopClosure(HeapRegion *hr) { }
3213 void do_oop(narrowOop *p) { do_oop_work(p); }
3214 void do_oop( oop *p) { do_oop_work(p); }
3215
3216 template <class T> void do_oop_work(T *p) {
3217 oop obj = oopDesc::load_decode_heap_oop(p);
3218 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3219 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3220 p2i(p), p2i(obj));
3221 }
3222 };
3223
3224 class VerifyArchiveRegionClosure: public ObjectClosure {
3225 public:
3226 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3227 // Verify that all object pointers are to archive regions.
3228 void do_object(oop o) {
3229 VerifyArchiveOopClosure checkOop(NULL);
3230 assert(o != NULL, "Should not be here for NULL oops");
3231 o->oop_iterate_no_header(&checkOop);
3232 }
3233 };
3234
3235 class VerifyRegionClosure: public HeapRegionClosure {
3236 private:
3237 bool _par;
3238 VerifyOption _vo;
3239 bool _failures;
3240 public:
3241 // _vo == UsePrevMarking -> use "prev" marking information,
3242 // _vo == UseNextMarking -> use "next" marking information,
3243 // _vo == UseMarkWord -> use mark word from object header.
3244 VerifyRegionClosure(bool par, VerifyOption vo)
3245 : _par(par),
3246 _vo(vo),
3247 _failures(false) {}
3248
3249 bool failures() {
3250 return _failures;
3251 }
3252
3253 bool doHeapRegion(HeapRegion* r) {
3254 // For archive regions, verify there are no heap pointers to
3255 // non-pinned regions. For all others, verify liveness info.
3256 if (r->is_archive()) {
3257 VerifyArchiveRegionClosure verify_oop_pointers(r);
3258 r->object_iterate(&verify_oop_pointers);
3259 return true;
3260 }
3261 if (!r->is_continues_humongous()) {
3262 bool failures = false;
3263 r->verify(_vo, &failures);
3264 if (failures) {
3265 _failures = true;
3266 } else {
3267 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3268 r->object_iterate(¬_dead_yet_cl);
3269 if (_vo != VerifyOption_G1UseNextMarking) {
3270 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3271 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3272 "max_live_bytes " SIZE_FORMAT " "
3273 "< calculated " SIZE_FORMAT,
3274 p2i(r->bottom()), p2i(r->end()),
3275 r->max_live_bytes(),
3276 not_dead_yet_cl.live_bytes());
3277 _failures = true;
3278 }
3279 } else {
3280 // When vo == UseNextMarking we cannot currently do a sanity
3281 // check on the live bytes as the calculation has not been
3282 // finalized yet.
3283 }
3284 }
3285 }
3286 return false; // stop the region iteration if we hit a failure
3287 }
3288 };
3289
3290 // This is the task used for parallel verification of the heap regions
3291
3292 class G1ParVerifyTask: public AbstractGangTask {
3293 private:
3294 G1CollectedHeap* _g1h;
3295 VerifyOption _vo;
3296 bool _failures;
3297 HeapRegionClaimer _hrclaimer;
3298
3299 public:
3300 // _vo == UsePrevMarking -> use "prev" marking information,
3301 // _vo == UseNextMarking -> use "next" marking information,
3302 // _vo == UseMarkWord -> use mark word from object header.
3303 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3304 AbstractGangTask("Parallel verify task"),
3305 _g1h(g1h),
3306 _vo(vo),
3307 _failures(false),
3308 _hrclaimer(g1h->workers()->active_workers()) {}
3309
3310 bool failures() {
3311 return _failures;
3312 }
3313
3314 void work(uint worker_id) {
3315 HandleMark hm;
3316 VerifyRegionClosure blk(true, _vo);
3317 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3318 if (blk.failures()) {
3319 _failures = true;
3320 }
3321 }
3322 };
3323
3324 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3325 if (SafepointSynchronize::is_at_safepoint()) {
3326 assert(Thread::current()->is_VM_thread(),
3327 "Expected to be executed serially by the VM thread at this point");
3328
3329 if (!silent) { gclog_or_tty->print("Roots "); }
3330 VerifyRootsClosure rootsCl(vo);
3331 VerifyKlassClosure klassCl(this, &rootsCl);
3332 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3333
3334 // We apply the relevant closures to all the oops in the
3335 // system dictionary, class loader data graph, the string table
3336 // and the nmethods in the code cache.
3337 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3338 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3339
3340 {
3341 G1RootProcessor root_processor(this, 1);
3342 root_processor.process_all_roots(&rootsCl,
3343 &cldCl,
3344 &blobsCl);
3345 }
3346
3347 bool failures = rootsCl.failures() || codeRootsCl.failures();
3348
3349 if (vo != VerifyOption_G1UseMarkWord) {
3350 // If we're verifying during a full GC then the region sets
3351 // will have been torn down at the start of the GC. Therefore
3352 // verifying the region sets will fail. So we only verify
3353 // the region sets when not in a full GC.
3354 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3355 verify_region_sets();
3356 }
3357
3358 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3359 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3360
3361 G1ParVerifyTask task(this, vo);
3362 workers()->run_task(&task);
3363 if (task.failures()) {
3364 failures = true;
3365 }
3366
3367 } else {
3368 VerifyRegionClosure blk(false, vo);
3369 heap_region_iterate(&blk);
3370 if (blk.failures()) {
3371 failures = true;
3372 }
3373 }
3374
3375 if (G1StringDedup::is_enabled()) {
3376 if (!silent) gclog_or_tty->print("StrDedup ");
3377 G1StringDedup::verify();
3378 }
3379
3380 if (failures) {
3381 gclog_or_tty->print_cr("Heap:");
3382 // It helps to have the per-region information in the output to
3383 // help us track down what went wrong. This is why we call
3384 // print_extended_on() instead of print_on().
3385 print_extended_on(gclog_or_tty);
3386 gclog_or_tty->cr();
3387 gclog_or_tty->flush();
3388 }
3389 guarantee(!failures, "there should not have been any failures");
3390 } else {
3391 if (!silent) {
3392 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3393 if (G1StringDedup::is_enabled()) {
3394 gclog_or_tty->print(", StrDedup");
3395 }
3396 gclog_or_tty->print(") ");
3397 }
3398 }
3399 }
3400
3401 void G1CollectedHeap::verify(bool silent) {
3402 verify(silent, VerifyOption_G1UsePrevMarking);
3403 }
3404
3405 double G1CollectedHeap::verify(bool guard, const char* msg) {
3406 double verify_time_ms = 0.0;
3407
3408 if (guard && total_collections() >= VerifyGCStartAt) {
3409 double verify_start = os::elapsedTime();
3410 HandleMark hm; // Discard invalid handles created during verification
3411 prepare_for_verify();
3412 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3413 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3414 }
3415
3416 return verify_time_ms;
3417 }
3418
3419 void G1CollectedHeap::verify_before_gc() {
3420 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3421 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3422 }
3423
3424 void G1CollectedHeap::verify_after_gc() {
3425 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3426 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3427 }
3428
3429 class PrintRegionClosure: public HeapRegionClosure {
3430 outputStream* _st;
3431 public:
3432 PrintRegionClosure(outputStream* st) : _st(st) {}
3433 bool doHeapRegion(HeapRegion* r) {
3434 r->print_on(_st);
3435 return false;
3436 }
3437 };
3438
3439 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3440 const HeapRegion* hr,
3441 const VerifyOption vo) const {
3442 switch (vo) {
3443 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3444 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3445 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3446 default: ShouldNotReachHere();
3447 }
3448 return false; // keep some compilers happy
3449 }
3450
3451 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3452 const VerifyOption vo) const {
3453 switch (vo) {
3454 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3455 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3456 case VerifyOption_G1UseMarkWord: {
3457 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3458 return !obj->is_gc_marked() && !hr->is_archive();
3459 }
3460 default: ShouldNotReachHere();
3461 }
3462 return false; // keep some compilers happy
3463 }
3464
3465 void G1CollectedHeap::print_on(outputStream* st) const {
3466 st->print(" %-20s", "garbage-first heap");
3467 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3468 capacity()/K, used_unlocked()/K);
3469 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3470 p2i(_hrm.reserved().start()),
3471 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3472 p2i(_hrm.reserved().end()));
3473 st->cr();
3474 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3475 uint young_regions = _young_list->length();
3476 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3477 (size_t) young_regions * HeapRegion::GrainBytes / K);
3478 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3479 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3480 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3481 st->cr();
3482 MetaspaceAux::print_on(st);
3483 }
3484
3485 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3486 print_on(st);
3487
3488 // Print the per-region information.
3489 st->cr();
3490 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3491 "HS=humongous(starts), HC=humongous(continues), "
3492 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3493 "PTAMS=previous top-at-mark-start, "
3494 "NTAMS=next top-at-mark-start)");
3495 PrintRegionClosure blk(st);
3496 heap_region_iterate(&blk);
3497 }
3498
3499 void G1CollectedHeap::print_on_error(outputStream* st) const {
3500 this->CollectedHeap::print_on_error(st);
3501
3502 if (_cm != NULL) {
3503 st->cr();
3504 _cm->print_on_error(st);
3505 }
3506 }
3507
3508 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3509 workers()->print_worker_threads_on(st);
3510 _cmThread->print_on(st);
3511 st->cr();
3512 _cm->print_worker_threads_on(st);
3513 _cg1r->print_worker_threads_on(st);
3514 if (G1StringDedup::is_enabled()) {
3515 G1StringDedup::print_worker_threads_on(st);
3516 }
3517 }
3518
3519 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3520 workers()->threads_do(tc);
3521 tc->do_thread(_cmThread);
3522 _cg1r->threads_do(tc);
3523 if (G1StringDedup::is_enabled()) {
3524 G1StringDedup::threads_do(tc);
3525 }
3526 }
3527
3528 void G1CollectedHeap::print_tracing_info() const {
3529 // We'll overload this to mean "trace GC pause statistics."
3530 if (TraceYoungGenTime || TraceOldGenTime) {
3531 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3532 // to that.
3533 g1_policy()->print_tracing_info();
3534 }
3535 if (G1SummarizeRSetStats) {
3536 g1_rem_set()->print_summary_info();
3537 }
3538 if (G1SummarizeConcMark) {
3539 concurrent_mark()->print_summary_info();
3540 }
3541 g1_policy()->print_yg_surv_rate_info();
3542 }
3543
3544 #ifndef PRODUCT
3545 // Helpful for debugging RSet issues.
3546
3547 class PrintRSetsClosure : public HeapRegionClosure {
3548 private:
3549 const char* _msg;
3550 size_t _occupied_sum;
3551
3552 public:
3553 bool doHeapRegion(HeapRegion* r) {
3554 HeapRegionRemSet* hrrs = r->rem_set();
3555 size_t occupied = hrrs->occupied();
3556 _occupied_sum += occupied;
3557
3558 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3559 HR_FORMAT_PARAMS(r));
3560 if (occupied == 0) {
3561 gclog_or_tty->print_cr(" RSet is empty");
3562 } else {
3563 hrrs->print();
3564 }
3565 gclog_or_tty->print_cr("----------");
3566 return false;
3567 }
3568
3569 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3570 gclog_or_tty->cr();
3571 gclog_or_tty->print_cr("========================================");
3572 gclog_or_tty->print_cr("%s", msg);
3573 gclog_or_tty->cr();
3574 }
3575
3576 ~PrintRSetsClosure() {
3577 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3578 gclog_or_tty->print_cr("========================================");
3579 gclog_or_tty->cr();
3580 }
3581 };
3582
3583 void G1CollectedHeap::print_cset_rsets() {
3584 PrintRSetsClosure cl("Printing CSet RSets");
3585 collection_set_iterate(&cl);
3586 }
3587
3588 void G1CollectedHeap::print_all_rsets() {
3589 PrintRSetsClosure cl("Printing All RSets");;
3590 heap_region_iterate(&cl);
3591 }
3592 #endif // PRODUCT
3593
3594 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3595 YoungList* young_list = heap()->young_list();
3596
3597 size_t eden_used_bytes = young_list->eden_used_bytes();
3598 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3599
3600 size_t eden_capacity_bytes =
3601 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3602
3603 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3604 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3605 }
3606
3607 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3608 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3609 stats->unused(), stats->used(), stats->region_end_waste(),
3610 stats->regions_filled(), stats->direct_allocated(),
3611 stats->failure_used(), stats->failure_waste());
3612 }
3613
3614 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3615 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3616 gc_tracer->report_gc_heap_summary(when, heap_summary);
3617
3618 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3619 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3620 }
3621
3622
3623 G1CollectedHeap* G1CollectedHeap::heap() {
3624 CollectedHeap* heap = Universe::heap();
3625 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3626 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3627 return (G1CollectedHeap*)heap;
3628 }
3629
3630 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3631 // always_do_update_barrier = false;
3632 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3633 // Fill TLAB's and such
3634 accumulate_statistics_all_tlabs();
3635 ensure_parsability(true);
3636
3637 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3638 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3639 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3640 }
3641 }
3642
3643 void G1CollectedHeap::gc_epilogue(bool full) {
3644
3645 if (G1SummarizeRSetStats &&
3646 (G1SummarizeRSetStatsPeriod > 0) &&
3647 // we are at the end of the GC. Total collections has already been increased.
3648 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3649 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3650 }
3651
3652 // FIXME: what is this about?
3653 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3654 // is set.
3655 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3656 "derived pointer present"));
3657 // always_do_update_barrier = true;
3658
3659 resize_all_tlabs();
3660 allocation_context_stats().update(full);
3661
3662 // We have just completed a GC. Update the soft reference
3663 // policy with the new heap occupancy
3664 Universe::update_heap_info_at_gc();
3665 }
3666
3667 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3668 uint gc_count_before,
3669 bool* succeeded,
3670 GCCause::Cause gc_cause) {
3671 assert_heap_not_locked_and_not_at_safepoint();
3672 g1_policy()->record_stop_world_start();
3673 VM_G1IncCollectionPause op(gc_count_before,
3674 word_size,
3675 false, /* should_initiate_conc_mark */
3676 g1_policy()->max_pause_time_ms(),
3677 gc_cause);
3678
3679 op.set_allocation_context(AllocationContext::current());
3680 VMThread::execute(&op);
3681
3682 HeapWord* result = op.result();
3683 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3684 assert(result == NULL || ret_succeeded,
3685 "the result should be NULL if the VM did not succeed");
3686 *succeeded = ret_succeeded;
3687
3688 assert_heap_not_locked();
3689 return result;
3690 }
3691
3692 void
3693 G1CollectedHeap::doConcurrentMark() {
3694 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3695 if (!_cmThread->in_progress()) {
3696 _cmThread->set_started();
3697 CGC_lock->notify();
3698 }
3699 }
3700
3701 size_t G1CollectedHeap::pending_card_num() {
3702 size_t extra_cards = 0;
3703 JavaThread *curr = Threads::first();
3704 while (curr != NULL) {
3705 DirtyCardQueue& dcq = curr->dirty_card_queue();
3706 extra_cards += dcq.size();
3707 curr = curr->next();
3708 }
3709 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3710 size_t buffer_size = dcqs.buffer_size();
3711 size_t buffer_num = dcqs.completed_buffers_num();
3712
3713 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3714 // in bytes - not the number of 'entries'. We need to convert
3715 // into a number of cards.
3716 return (buffer_size * buffer_num + extra_cards) / oopSize;
3717 }
3718
3719 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3720 private:
3721 size_t _total_humongous;
3722 size_t _candidate_humongous;
3723
3724 DirtyCardQueue _dcq;
3725
3726 // We don't nominate objects with many remembered set entries, on
3727 // the assumption that such objects are likely still live.
3728 bool is_remset_small(HeapRegion* region) const {
3729 HeapRegionRemSet* const rset = region->rem_set();
3730 return G1EagerReclaimHumongousObjectsWithStaleRefs
3731 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3732 : rset->is_empty();
3733 }
3734
3735 bool is_typeArray_region(HeapRegion* region) const {
3736 return oop(region->bottom())->is_typeArray();
3737 }
3738
3739 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3740 assert(region->is_starts_humongous(), "Must start a humongous object");
3741
3742 // Candidate selection must satisfy the following constraints
3743 // while concurrent marking is in progress:
3744 //
3745 // * In order to maintain SATB invariants, an object must not be
3746 // reclaimed if it was allocated before the start of marking and
3747 // has not had its references scanned. Such an object must have
3748 // its references (including type metadata) scanned to ensure no
3749 // live objects are missed by the marking process. Objects
3750 // allocated after the start of concurrent marking don't need to
3751 // be scanned.
3752 //
3753 // * An object must not be reclaimed if it is on the concurrent
3754 // mark stack. Objects allocated after the start of concurrent
3755 // marking are never pushed on the mark stack.
3756 //
3757 // Nominating only objects allocated after the start of concurrent
3758 // marking is sufficient to meet both constraints. This may miss
3759 // some objects that satisfy the constraints, but the marking data
3760 // structures don't support efficiently performing the needed
3761 // additional tests or scrubbing of the mark stack.
3762 //
3763 // However, we presently only nominate is_typeArray() objects.
3764 // A humongous object containing references induces remembered
3765 // set entries on other regions. In order to reclaim such an
3766 // object, those remembered sets would need to be cleaned up.
3767 //
3768 // We also treat is_typeArray() objects specially, allowing them
3769 // to be reclaimed even if allocated before the start of
3770 // concurrent mark. For this we rely on mark stack insertion to
3771 // exclude is_typeArray() objects, preventing reclaiming an object
3772 // that is in the mark stack. We also rely on the metadata for
3773 // such objects to be built-in and so ensured to be kept live.
3774 // Frequent allocation and drop of large binary blobs is an
3775 // important use case for eager reclaim, and this special handling
3776 // may reduce needed headroom.
3777
3778 return is_typeArray_region(region) && is_remset_small(region);
3779 }
3780
3781 public:
3782 RegisterHumongousWithInCSetFastTestClosure()
3783 : _total_humongous(0),
3784 _candidate_humongous(0),
3785 _dcq(&JavaThread::dirty_card_queue_set()) {
3786 }
3787
3788 virtual bool doHeapRegion(HeapRegion* r) {
3789 if (!r->is_starts_humongous()) {
3790 return false;
3791 }
3792 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3793
3794 bool is_candidate = humongous_region_is_candidate(g1h, r);
3795 uint rindex = r->hrm_index();
3796 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3797 if (is_candidate) {
3798 _candidate_humongous++;
3799 g1h->register_humongous_region_with_cset(rindex);
3800 // Is_candidate already filters out humongous object with large remembered sets.
3801 // If we have a humongous object with a few remembered sets, we simply flush these
3802 // remembered set entries into the DCQS. That will result in automatic
3803 // re-evaluation of their remembered set entries during the following evacuation
3804 // phase.
3805 if (!r->rem_set()->is_empty()) {
3806 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3807 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3808 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3809 HeapRegionRemSetIterator hrrs(r->rem_set());
3810 size_t card_index;
3811 while (hrrs.has_next(card_index)) {
3812 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3813 // The remembered set might contain references to already freed
3814 // regions. Filter out such entries to avoid failing card table
3815 // verification.
3816 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3817 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3818 *card_ptr = CardTableModRefBS::dirty_card_val();
3819 _dcq.enqueue(card_ptr);
3820 }
3821 }
3822 }
3823 r->rem_set()->clear_locked();
3824 }
3825 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3826 }
3827 _total_humongous++;
3828
3829 return false;
3830 }
3831
3832 size_t total_humongous() const { return _total_humongous; }
3833 size_t candidate_humongous() const { return _candidate_humongous; }
3834
3835 void flush_rem_set_entries() { _dcq.flush(); }
3836 };
3837
3838 void G1CollectedHeap::register_humongous_regions_with_cset() {
3839 if (!G1EagerReclaimHumongousObjects) {
3840 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3841 return;
3842 }
3843 double time = os::elapsed_counter();
3844
3845 // Collect reclaim candidate information and register candidates with cset.
3846 RegisterHumongousWithInCSetFastTestClosure cl;
3847 heap_region_iterate(&cl);
3848
3849 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3850 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3851 cl.total_humongous(),
3852 cl.candidate_humongous());
3853 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3854
3855 // Finally flush all remembered set entries to re-check into the global DCQS.
3856 cl.flush_rem_set_entries();
3857 }
3858
3859 #ifdef ASSERT
3860 class VerifyCSetClosure: public HeapRegionClosure {
3861 public:
3862 bool doHeapRegion(HeapRegion* hr) {
3863 // Here we check that the CSet region's RSet is ready for parallel
3864 // iteration. The fields that we'll verify are only manipulated
3865 // when the region is part of a CSet and is collected. Afterwards,
3866 // we reset these fields when we clear the region's RSet (when the
3867 // region is freed) so they are ready when the region is
3868 // re-allocated. The only exception to this is if there's an
3869 // evacuation failure and instead of freeing the region we leave
3870 // it in the heap. In that case, we reset these fields during
3871 // evacuation failure handling.
3872 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3873
3874 // Here's a good place to add any other checks we'd like to
3875 // perform on CSet regions.
3876 return false;
3877 }
3878 };
3879 #endif // ASSERT
3880
3881 uint G1CollectedHeap::num_task_queues() const {
3882 return _task_queues->size();
3883 }
3884
3885 #if TASKQUEUE_STATS
3886 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3887 st->print_raw_cr("GC Task Stats");
3888 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3889 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3890 }
3891
3892 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3893 print_taskqueue_stats_hdr(st);
3894
3895 TaskQueueStats totals;
3896 const uint n = num_task_queues();
3897 for (uint i = 0; i < n; ++i) {
3898 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3899 totals += task_queue(i)->stats;
3900 }
3901 st->print_raw("tot "); totals.print(st); st->cr();
3902
3903 DEBUG_ONLY(totals.verify());
3904 }
3905
3906 void G1CollectedHeap::reset_taskqueue_stats() {
3907 const uint n = num_task_queues();
3908 for (uint i = 0; i < n; ++i) {
3909 task_queue(i)->stats.reset();
3910 }
3911 }
3912 #endif // TASKQUEUE_STATS
3913
3914 void G1CollectedHeap::log_gc_header() {
3915 if (!G1Log::fine()) {
3916 return;
3917 }
3918
3919 gclog_or_tty->gclog_stamp();
3920
3921 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3922 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3923 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3924
3925 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3926 }
3927
3928 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3929 if (!G1Log::fine()) {
3930 return;
3931 }
3932
3933 if (G1Log::finer()) {
3934 if (evacuation_failed()) {
3935 gclog_or_tty->print(" (to-space exhausted)");
3936 }
3937 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3938 g1_policy()->phase_times()->note_gc_end();
3939 g1_policy()->phase_times()->print(pause_time_sec);
3940 g1_policy()->print_detailed_heap_transition();
3941 } else {
3942 if (evacuation_failed()) {
3943 gclog_or_tty->print("--");
3944 }
3945 g1_policy()->print_heap_transition();
3946 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3947 }
3948 gclog_or_tty->flush();
3949 }
3950
3951 void G1CollectedHeap::wait_for_root_region_scanning() {
3952 double scan_wait_start = os::elapsedTime();
3953 // We have to wait until the CM threads finish scanning the
3954 // root regions as it's the only way to ensure that all the
3955 // objects on them have been correctly scanned before we start
3956 // moving them during the GC.
3957 bool waited = _cm->root_regions()->wait_until_scan_finished();
3958 double wait_time_ms = 0.0;
3959 if (waited) {
3960 double scan_wait_end = os::elapsedTime();
3961 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3962 }
3963 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3964 }
3965
3966 bool
3967 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3968 assert_at_safepoint(true /* should_be_vm_thread */);
3969 guarantee(!is_gc_active(), "collection is not reentrant");
3970
3971 if (GC_locker::check_active_before_gc()) {
3972 return false;
3973 }
3974
3975 _gc_timer_stw->register_gc_start();
3976
3977 GCIdMark gc_id_mark;
3978 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3979
3980 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3981 ResourceMark rm;
3982
3983 wait_for_root_region_scanning();
3984
3985 G1Log::update_level();
3986 print_heap_before_gc();
3987 trace_heap_before_gc(_gc_tracer_stw);
3988
3989 verify_region_sets_optional();
3990 verify_dirty_young_regions();
3991
3992 // This call will decide whether this pause is an initial-mark
3993 // pause. If it is, during_initial_mark_pause() will return true
3994 // for the duration of this pause.
3995 g1_policy()->decide_on_conc_mark_initiation();
3996
3997 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3998 assert(!collector_state()->during_initial_mark_pause() ||
3999 collector_state()->gcs_are_young(), "sanity");
4000
4001 // We also do not allow mixed GCs during marking.
4002 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4003
4004 // Record whether this pause is an initial mark. When the current
4005 // thread has completed its logging output and it's safe to signal
4006 // the CM thread, the flag's value in the policy has been reset.
4007 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4008
4009 // Inner scope for scope based logging, timers, and stats collection
4010 {
4011 EvacuationInfo evacuation_info;
4012
4013 if (collector_state()->during_initial_mark_pause()) {
4014 // We are about to start a marking cycle, so we increment the
4015 // full collection counter.
4016 increment_old_marking_cycles_started();
4017 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4018 }
4019
4020 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4021
4022 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4023
4024 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4025 workers()->active_workers(),
4026 Threads::number_of_non_daemon_threads());
4027 workers()->set_active_workers(active_workers);
4028
4029 double pause_start_sec = os::elapsedTime();
4030 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4031 log_gc_header();
4032
4033 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4034 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4035
4036 // If the secondary_free_list is not empty, append it to the
4037 // free_list. No need to wait for the cleanup operation to finish;
4038 // the region allocation code will check the secondary_free_list
4039 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4040 // set, skip this step so that the region allocation code has to
4041 // get entries from the secondary_free_list.
4042 if (!G1StressConcRegionFreeing) {
4043 append_secondary_free_list_if_not_empty_with_lock();
4044 }
4045
4046 assert(check_young_list_well_formed(), "young list should be well formed");
4047
4048 // Don't dynamically change the number of GC threads this early. A value of
4049 // 0 is used to indicate serial work. When parallel work is done,
4050 // it will be set.
4051
4052 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4053 IsGCActiveMark x;
4054
4055 gc_prologue(false);
4056 increment_total_collections(false /* full gc */);
4057 increment_gc_time_stamp();
4058
4059 verify_before_gc();
4060
4061 check_bitmaps("GC Start");
4062
4063 COMPILER2_PRESENT(DerivedPointerTable::clear());
4064
4065 // Please see comment in g1CollectedHeap.hpp and
4066 // G1CollectedHeap::ref_processing_init() to see how
4067 // reference processing currently works in G1.
4068
4069 // Enable discovery in the STW reference processor
4070 ref_processor_stw()->enable_discovery();
4071
4072 {
4073 // We want to temporarily turn off discovery by the
4074 // CM ref processor, if necessary, and turn it back on
4075 // on again later if we do. Using a scoped
4076 // NoRefDiscovery object will do this.
4077 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4078
4079 // Forget the current alloc region (we might even choose it to be part
4080 // of the collection set!).
4081 _allocator->release_mutator_alloc_region();
4082
4083 // We should call this after we retire the mutator alloc
4084 // region(s) so that all the ALLOC / RETIRE events are generated
4085 // before the start GC event.
4086 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4087
4088 // This timing is only used by the ergonomics to handle our pause target.
4089 // It is unclear why this should not include the full pause. We will
4090 // investigate this in CR 7178365.
4091 //
4092 // Preserving the old comment here if that helps the investigation:
4093 //
4094 // The elapsed time induced by the start time below deliberately elides
4095 // the possible verification above.
4096 double sample_start_time_sec = os::elapsedTime();
4097
4098 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4099
4100 if (collector_state()->during_initial_mark_pause()) {
4101 concurrent_mark()->checkpointRootsInitialPre();
4102 }
4103
4104 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
4105 g1_policy()->finalize_old_cset_part(time_remaining_ms);
4106
4107 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4108
4109 register_humongous_regions_with_cset();
4110
4111 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4112
4113 _cm->note_start_of_gc();
4114 // We call this after finalize_cset() to
4115 // ensure that the CSet has been finalized.
4116 _cm->verify_no_cset_oops();
4117
4118 if (_hr_printer.is_active()) {
4119 HeapRegion* hr = g1_policy()->collection_set();
4120 while (hr != NULL) {
4121 _hr_printer.cset(hr);
4122 hr = hr->next_in_collection_set();
4123 }
4124 }
4125
4126 #ifdef ASSERT
4127 VerifyCSetClosure cl;
4128 collection_set_iterate(&cl);
4129 #endif // ASSERT
4130
4131 // Initialize the GC alloc regions.
4132 _allocator->init_gc_alloc_regions(evacuation_info);
4133
4134 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
4135 // Actually do the work...
4136 evacuate_collection_set(evacuation_info, &per_thread_states);
4137
4138 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
4139 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
4140
4141 eagerly_reclaim_humongous_regions();
4142
4143 g1_policy()->clear_collection_set();
4144
4145 // Start a new incremental collection set for the next pause.
4146 g1_policy()->start_incremental_cset_building();
4147
4148 clear_cset_fast_test();
4149
4150 _young_list->reset_sampled_info();
4151
4152 // Don't check the whole heap at this point as the
4153 // GC alloc regions from this pause have been tagged
4154 // as survivors and moved on to the survivor list.
4155 // Survivor regions will fail the !is_young() check.
4156 assert(check_young_list_empty(false /* check_heap */),
4157 "young list should be empty");
4158
4159 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4160 _young_list->first_survivor_region(),
4161 _young_list->last_survivor_region());
4162
4163 _young_list->reset_auxilary_lists();
4164
4165 if (evacuation_failed()) {
4166 set_used(recalculate_used());
4167 if (_archive_allocator != NULL) {
4168 _archive_allocator->clear_used();
4169 }
4170 for (uint i = 0; i < ParallelGCThreads; i++) {
4171 if (_evacuation_failed_info_array[i].has_failed()) {
4172 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4173 }
4174 }
4175 } else {
4176 // The "used" of the the collection set have already been subtracted
4177 // when they were freed. Add in the bytes evacuated.
4178 increase_used(g1_policy()->bytes_copied_during_gc());
4179 }
4180
4181 if (collector_state()->during_initial_mark_pause()) {
4182 // We have to do this before we notify the CM threads that
4183 // they can start working to make sure that all the
4184 // appropriate initialization is done on the CM object.
4185 concurrent_mark()->checkpointRootsInitialPost();
4186 collector_state()->set_mark_in_progress(true);
4187 // Note that we don't actually trigger the CM thread at
4188 // this point. We do that later when we're sure that
4189 // the current thread has completed its logging output.
4190 }
4191
4192 allocate_dummy_regions();
4193
4194 _allocator->init_mutator_alloc_region();
4195
4196 {
4197 size_t expand_bytes = g1_policy()->expansion_amount();
4198 if (expand_bytes > 0) {
4199 size_t bytes_before = capacity();
4200 // No need for an ergo verbose message here,
4201 // expansion_amount() does this when it returns a value > 0.
4202 if (!expand(expand_bytes)) {
4203 // We failed to expand the heap. Cannot do anything about it.
4204 }
4205 }
4206 }
4207
4208 // We redo the verification but now wrt to the new CSet which
4209 // has just got initialized after the previous CSet was freed.
4210 _cm->verify_no_cset_oops();
4211 _cm->note_end_of_gc();
4212
4213 // This timing is only used by the ergonomics to handle our pause target.
4214 // It is unclear why this should not include the full pause. We will
4215 // investigate this in CR 7178365.
4216 double sample_end_time_sec = os::elapsedTime();
4217 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4218 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4219 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4220
4221 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4222 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4223
4224 MemoryService::track_memory_usage();
4225
4226 // In prepare_for_verify() below we'll need to scan the deferred
4227 // update buffers to bring the RSets up-to-date if
4228 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4229 // the update buffers we'll probably need to scan cards on the
4230 // regions we just allocated to (i.e., the GC alloc
4231 // regions). However, during the last GC we called
4232 // set_saved_mark() on all the GC alloc regions, so card
4233 // scanning might skip the [saved_mark_word()...top()] area of
4234 // those regions (i.e., the area we allocated objects into
4235 // during the last GC). But it shouldn't. Given that
4236 // saved_mark_word() is conditional on whether the GC time stamp
4237 // on the region is current or not, by incrementing the GC time
4238 // stamp here we invalidate all the GC time stamps on all the
4239 // regions and saved_mark_word() will simply return top() for
4240 // all the regions. This is a nicer way of ensuring this rather
4241 // than iterating over the regions and fixing them. In fact, the
4242 // GC time stamp increment here also ensures that
4243 // saved_mark_word() will return top() between pauses, i.e.,
4244 // during concurrent refinement. So we don't need the
4245 // is_gc_active() check to decided which top to use when
4246 // scanning cards (see CR 7039627).
4247 increment_gc_time_stamp();
4248
4249 verify_after_gc();
4250 check_bitmaps("GC End");
4251
4252 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4253 ref_processor_stw()->verify_no_references_recorded();
4254
4255 // CM reference discovery will be re-enabled if necessary.
4256 }
4257
4258 // We should do this after we potentially expand the heap so
4259 // that all the COMMIT events are generated before the end GC
4260 // event, and after we retire the GC alloc regions so that all
4261 // RETIRE events are generated before the end GC event.
4262 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4263
4264 #ifdef TRACESPINNING
4265 ParallelTaskTerminator::print_termination_counts();
4266 #endif
4267
4268 gc_epilogue(false);
4269 }
4270
4271 // Print the remainder of the GC log output.
4272 log_gc_footer(os::elapsedTime() - pause_start_sec);
4273
4274 // It is not yet to safe to tell the concurrent mark to
4275 // start as we have some optional output below. We don't want the
4276 // output from the concurrent mark thread interfering with this
4277 // logging output either.
4278
4279 _hrm.verify_optional();
4280 verify_region_sets_optional();
4281
4282 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4283 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4284
4285 print_heap_after_gc();
4286 trace_heap_after_gc(_gc_tracer_stw);
4287
4288 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4289 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4290 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4291 // before any GC notifications are raised.
4292 g1mm()->update_sizes();
4293
4294 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4295 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4296 _gc_timer_stw->register_gc_end();
4297 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4298 }
4299 // It should now be safe to tell the concurrent mark thread to start
4300 // without its logging output interfering with the logging output
4301 // that came from the pause.
4302
4303 if (should_start_conc_mark) {
4304 // CAUTION: after the doConcurrentMark() call below,
4305 // the concurrent marking thread(s) could be running
4306 // concurrently with us. Make sure that anything after
4307 // this point does not assume that we are the only GC thread
4308 // running. Note: of course, the actual marking work will
4309 // not start until the safepoint itself is released in
4310 // SuspendibleThreadSet::desynchronize().
4311 doConcurrentMark();
4312 }
4313
4314 return true;
4315 }
4316
4317 void G1CollectedHeap::remove_self_forwarding_pointers() {
4318 double remove_self_forwards_start = os::elapsedTime();
4319
4320 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4321 workers()->run_task(&rsfp_task);
4322
4323 // Now restore saved marks, if any.
4324 for (uint i = 0; i < ParallelGCThreads; i++) {
4325 OopAndMarkOopStack& cur = _preserved_objs[i];
4326 while (!cur.is_empty()) {
4327 OopAndMarkOop elem = cur.pop();
4328 elem.set_mark();
4329 }
4330 cur.clear(true);
4331 }
4332
4333 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4334 }
4335
4336 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4337 if (!_evacuation_failed) {
4338 _evacuation_failed = true;
4339 }
4340
4341 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4342
4343 // We want to call the "for_promotion_failure" version only in the
4344 // case of a promotion failure.
4345 if (m->must_be_preserved_for_promotion_failure(obj)) {
4346 OopAndMarkOop elem(obj, m);
4347 _preserved_objs[worker_id].push(elem);
4348 }
4349 }
4350
4351 void G1ParCopyHelper::mark_object(oop obj) {
4352 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4353
4354 // We know that the object is not moving so it's safe to read its size.
4355 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4356 }
4357
4358 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4359 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4360 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4361 assert(from_obj != to_obj, "should not be self-forwarded");
4362
4363 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4364 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4365
4366 // The object might be in the process of being copied by another
4367 // worker so we cannot trust that its to-space image is
4368 // well-formed. So we have to read its size from its from-space
4369 // image which we know should not be changing.
4370 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4371 }
4372
4373 template <class T>
4374 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4375 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4376 _scanned_klass->record_modified_oops();
4377 }
4378 }
4379
4380 template <G1Barrier barrier, G1Mark do_mark_object>
4381 template <class T>
4382 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4383 T heap_oop = oopDesc::load_heap_oop(p);
4384
4385 if (oopDesc::is_null(heap_oop)) {
4386 return;
4387 }
4388
4389 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4390
4391 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4392
4393 const InCSetState state = _g1->in_cset_state(obj);
4394 if (state.is_in_cset()) {
4395 oop forwardee;
4396 markOop m = obj->mark();
4397 if (m->is_marked()) {
4398 forwardee = (oop) m->decode_pointer();
4399 } else {
4400 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4401 }
4402 assert(forwardee != NULL, "forwardee should not be NULL");
4403 oopDesc::encode_store_heap_oop(p, forwardee);
4404 if (do_mark_object != G1MarkNone && forwardee != obj) {
4405 // If the object is self-forwarded we don't need to explicitly
4406 // mark it, the evacuation failure protocol will do so.
4407 mark_forwarded_object(obj, forwardee);
4408 }
4409
4410 if (barrier == G1BarrierKlass) {
4411 do_klass_barrier(p, forwardee);
4412 }
4413 } else {
4414 if (state.is_humongous()) {
4415 _g1->set_humongous_is_live(obj);
4416 }
4417 // The object is not in collection set. If we're a root scanning
4418 // closure during an initial mark pause then attempt to mark the object.
4419 if (do_mark_object == G1MarkFromRoot) {
4420 mark_object(obj);
4421 }
4422 }
4423 }
4424
4425 class G1ParEvacuateFollowersClosure : public VoidClosure {
4426 private:
4427 double _start_term;
4428 double _term_time;
4429 size_t _term_attempts;
4430
4431 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4432 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4433 protected:
4434 G1CollectedHeap* _g1h;
4435 G1ParScanThreadState* _par_scan_state;
4436 RefToScanQueueSet* _queues;
4437 ParallelTaskTerminator* _terminator;
4438
4439 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4440 RefToScanQueueSet* queues() { return _queues; }
4441 ParallelTaskTerminator* terminator() { return _terminator; }
4442
4443 public:
4444 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4445 G1ParScanThreadState* par_scan_state,
4446 RefToScanQueueSet* queues,
4447 ParallelTaskTerminator* terminator)
4448 : _g1h(g1h), _par_scan_state(par_scan_state),
4449 _queues(queues), _terminator(terminator),
4450 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4451
4452 void do_void();
4453
4454 double term_time() const { return _term_time; }
4455 size_t term_attempts() const { return _term_attempts; }
4456
4457 private:
4458 inline bool offer_termination();
4459 };
4460
4461 bool G1ParEvacuateFollowersClosure::offer_termination() {
4462 G1ParScanThreadState* const pss = par_scan_state();
4463 start_term_time();
4464 const bool res = terminator()->offer_termination();
4465 end_term_time();
4466 return res;
4467 }
4468
4469 void G1ParEvacuateFollowersClosure::do_void() {
4470 G1ParScanThreadState* const pss = par_scan_state();
4471 pss->trim_queue();
4472 do {
4473 pss->steal_and_trim_queue(queues());
4474 } while (!offer_termination());
4475 }
4476
4477 class G1KlassScanClosure : public KlassClosure {
4478 G1ParCopyHelper* _closure;
4479 bool _process_only_dirty;
4480 int _count;
4481 public:
4482 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4483 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4484 void do_klass(Klass* klass) {
4485 // If the klass has not been dirtied we know that there's
4486 // no references into the young gen and we can skip it.
4487 if (!_process_only_dirty || klass->has_modified_oops()) {
4488 // Clean the klass since we're going to scavenge all the metadata.
4489 klass->clear_modified_oops();
4490
4491 // Tell the closure that this klass is the Klass to scavenge
4492 // and is the one to dirty if oops are left pointing into the young gen.
4493 _closure->set_scanned_klass(klass);
4494
4495 klass->oops_do(_closure);
4496
4497 _closure->set_scanned_klass(NULL);
4498 }
4499 _count++;
4500 }
4501 };
4502
4503 class G1ParTask : public AbstractGangTask {
4504 protected:
4505 G1CollectedHeap* _g1h;
4506 G1ParScanThreadStateSet* _pss;
4507 RefToScanQueueSet* _queues;
4508 G1RootProcessor* _root_processor;
4509 ParallelTaskTerminator _terminator;
4510 uint _n_workers;
4511
4512 public:
4513 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4514 : AbstractGangTask("G1 collection"),
4515 _g1h(g1h),
4516 _pss(per_thread_states),
4517 _queues(task_queues),
4518 _root_processor(root_processor),
4519 _terminator(n_workers, _queues),
4520 _n_workers(n_workers)
4521 {}
4522
4523 RefToScanQueueSet* queues() { return _queues; }
4524
4525 RefToScanQueue *work_queue(int i) {
4526 return queues()->queue(i);
4527 }
4528
4529 ParallelTaskTerminator* terminator() { return &_terminator; }
4530
4531 // Helps out with CLD processing.
4532 //
4533 // During InitialMark we need to:
4534 // 1) Scavenge all CLDs for the young GC.
4535 // 2) Mark all objects directly reachable from strong CLDs.
4536 template <G1Mark do_mark_object>
4537 class G1CLDClosure : public CLDClosure {
4538 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4539 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4540 G1KlassScanClosure _klass_in_cld_closure;
4541 bool _claim;
4542
4543 public:
4544 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4545 bool only_young, bool claim)
4546 : _oop_closure(oop_closure),
4547 _oop_in_klass_closure(oop_closure->g1(),
4548 oop_closure->pss()),
4549 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4550 _claim(claim) {
4551
4552 }
4553
4554 void do_cld(ClassLoaderData* cld) {
4555 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4556 }
4557 };
4558
4559 void work(uint worker_id) {
4560 if (worker_id >= _n_workers) return; // no work needed this round
4561
4562 double start_sec = os::elapsedTime();
4563 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4564
4565 {
4566 ResourceMark rm;
4567 HandleMark hm;
4568
4569 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4570
4571 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4572 pss->set_ref_processor(rp);
4573
4574 bool only_young = _g1h->collector_state()->gcs_are_young();
4575
4576 // Non-IM young GC.
4577 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss);
4578 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4579 only_young, // Only process dirty klasses.
4580 false); // No need to claim CLDs.
4581 // IM young GC.
4582 // Strong roots closures.
4583 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss);
4584 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4585 false, // Process all klasses.
4586 true); // Need to claim CLDs.
4587 // Weak roots closures.
4588 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4589 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4590 false, // Process all klasses.
4591 true); // Need to claim CLDs.
4592
4593 OopClosure* strong_root_cl;
4594 OopClosure* weak_root_cl;
4595 CLDClosure* strong_cld_cl;
4596 CLDClosure* weak_cld_cl;
4597
4598 bool trace_metadata = false;
4599
4600 if (_g1h->collector_state()->during_initial_mark_pause()) {
4601 // We also need to mark copied objects.
4602 strong_root_cl = &scan_mark_root_cl;
4603 strong_cld_cl = &scan_mark_cld_cl;
4604 if (ClassUnloadingWithConcurrentMark) {
4605 weak_root_cl = &scan_mark_weak_root_cl;
4606 weak_cld_cl = &scan_mark_weak_cld_cl;
4607 trace_metadata = true;
4608 } else {
4609 weak_root_cl = &scan_mark_root_cl;
4610 weak_cld_cl = &scan_mark_cld_cl;
4611 }
4612 } else {
4613 strong_root_cl = &scan_only_root_cl;
4614 weak_root_cl = &scan_only_root_cl;
4615 strong_cld_cl = &scan_only_cld_cl;
4616 weak_cld_cl = &scan_only_cld_cl;
4617 }
4618
4619 double start_strong_roots_sec = os::elapsedTime();
4620 _root_processor->evacuate_roots(strong_root_cl,
4621 weak_root_cl,
4622 strong_cld_cl,
4623 weak_cld_cl,
4624 trace_metadata,
4625 worker_id);
4626
4627 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4628 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4629 weak_root_cl,
4630 worker_id);
4631
4632 _pss->add_cards_scanned(worker_id, cards_scanned);
4633
4634 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4635
4636 double term_sec = 0.0;
4637 size_t evac_term_attempts = 0;
4638 {
4639 double start = os::elapsedTime();
4640 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4641 evac.do_void();
4642
4643 evac_term_attempts = evac.term_attempts();
4644 term_sec = evac.term_time();
4645 double elapsed_sec = os::elapsedTime() - start;
4646 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4647 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4648 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4649 }
4650
4651 assert(pss->queue_is_empty(), "should be empty");
4652
4653 if (PrintTerminationStats) {
4654 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4655 size_t lab_waste;
4656 size_t lab_undo_waste;
4657 pss->waste(lab_waste, lab_undo_waste);
4658 _g1h->print_termination_stats(gclog_or_tty,
4659 worker_id,
4660 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4661 strong_roots_sec * 1000.0, /* strong roots time */
4662 term_sec * 1000.0, /* evac term time */
4663 evac_term_attempts, /* evac term attempts */
4664 lab_waste, /* alloc buffer waste */
4665 lab_undo_waste /* undo waste */
4666 );
4667 }
4668
4669 // Close the inner scope so that the ResourceMark and HandleMark
4670 // destructors are executed here and are included as part of the
4671 // "GC Worker Time".
4672 }
4673 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4674 }
4675 };
4676
4677 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4678 st->print_raw_cr("GC Termination Stats");
4679 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4680 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4681 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4682 }
4683
4684 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4685 uint worker_id,
4686 double elapsed_ms,
4687 double strong_roots_ms,
4688 double term_ms,
4689 size_t term_attempts,
4690 size_t alloc_buffer_waste,
4691 size_t undo_waste) const {
4692 st->print_cr("%3d %9.2f %9.2f %6.2f "
4693 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4694 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4695 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4696 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4697 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4698 alloc_buffer_waste * HeapWordSize / K,
4699 undo_waste * HeapWordSize / K);
4700 }
4701
4702 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4703 private:
4704 BoolObjectClosure* _is_alive;
4705 int _initial_string_table_size;
4706 int _initial_symbol_table_size;
4707
4708 bool _process_strings;
4709 int _strings_processed;
4710 int _strings_removed;
4711
4712 bool _process_symbols;
4713 int _symbols_processed;
4714 int _symbols_removed;
4715
4716 public:
4717 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4718 AbstractGangTask("String/Symbol Unlinking"),
4719 _is_alive(is_alive),
4720 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4721 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4722
4723 _initial_string_table_size = StringTable::the_table()->table_size();
4724 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4725 if (process_strings) {
4726 StringTable::clear_parallel_claimed_index();
4727 }
4728 if (process_symbols) {
4729 SymbolTable::clear_parallel_claimed_index();
4730 }
4731 }
4732
4733 ~G1StringSymbolTableUnlinkTask() {
4734 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4735 "claim value %d after unlink less than initial string table size %d",
4736 StringTable::parallel_claimed_index(), _initial_string_table_size);
4737 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4738 "claim value %d after unlink less than initial symbol table size %d",
4739 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4740
4741 if (G1TraceStringSymbolTableScrubbing) {
4742 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4743 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4744 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4745 strings_processed(), strings_removed(),
4746 symbols_processed(), symbols_removed());
4747 }
4748 }
4749
4750 void work(uint worker_id) {
4751 int strings_processed = 0;
4752 int strings_removed = 0;
4753 int symbols_processed = 0;
4754 int symbols_removed = 0;
4755 if (_process_strings) {
4756 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4757 Atomic::add(strings_processed, &_strings_processed);
4758 Atomic::add(strings_removed, &_strings_removed);
4759 }
4760 if (_process_symbols) {
4761 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4762 Atomic::add(symbols_processed, &_symbols_processed);
4763 Atomic::add(symbols_removed, &_symbols_removed);
4764 }
4765 }
4766
4767 size_t strings_processed() const { return (size_t)_strings_processed; }
4768 size_t strings_removed() const { return (size_t)_strings_removed; }
4769
4770 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4771 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4772 };
4773
4774 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4775 private:
4776 static Monitor* _lock;
4777
4778 BoolObjectClosure* const _is_alive;
4779 const bool _unloading_occurred;
4780 const uint _num_workers;
4781
4782 // Variables used to claim nmethods.
4783 nmethod* _first_nmethod;
4784 volatile nmethod* _claimed_nmethod;
4785
4786 // The list of nmethods that need to be processed by the second pass.
4787 volatile nmethod* _postponed_list;
4788 volatile uint _num_entered_barrier;
4789
4790 public:
4791 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4792 _is_alive(is_alive),
4793 _unloading_occurred(unloading_occurred),
4794 _num_workers(num_workers),
4795 _first_nmethod(NULL),
4796 _claimed_nmethod(NULL),
4797 _postponed_list(NULL),
4798 _num_entered_barrier(0)
4799 {
4800 nmethod::increase_unloading_clock();
4801 // Get first alive nmethod
4802 NMethodIterator iter = NMethodIterator();
4803 if(iter.next_alive()) {
4804 _first_nmethod = iter.method();
4805 }
4806 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4807 }
4808
4809 ~G1CodeCacheUnloadingTask() {
4810 CodeCache::verify_clean_inline_caches();
4811
4812 CodeCache::set_needs_cache_clean(false);
4813 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4814
4815 CodeCache::verify_icholder_relocations();
4816 }
4817
4818 private:
4819 void add_to_postponed_list(nmethod* nm) {
4820 nmethod* old;
4821 do {
4822 old = (nmethod*)_postponed_list;
4823 nm->set_unloading_next(old);
4824 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4825 }
4826
4827 void clean_nmethod(nmethod* nm) {
4828 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4829
4830 if (postponed) {
4831 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4832 add_to_postponed_list(nm);
4833 }
4834
4835 // Mark that this thread has been cleaned/unloaded.
4836 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4837 nm->set_unloading_clock(nmethod::global_unloading_clock());
4838 }
4839
4840 void clean_nmethod_postponed(nmethod* nm) {
4841 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4842 }
4843
4844 static const int MaxClaimNmethods = 16;
4845
4846 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4847 nmethod* first;
4848 NMethodIterator last;
4849
4850 do {
4851 *num_claimed_nmethods = 0;
4852
4853 first = (nmethod*)_claimed_nmethod;
4854 last = NMethodIterator(first);
4855
4856 if (first != NULL) {
4857
4858 for (int i = 0; i < MaxClaimNmethods; i++) {
4859 if (!last.next_alive()) {
4860 break;
4861 }
4862 claimed_nmethods[i] = last.method();
4863 (*num_claimed_nmethods)++;
4864 }
4865 }
4866
4867 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4868 }
4869
4870 nmethod* claim_postponed_nmethod() {
4871 nmethod* claim;
4872 nmethod* next;
4873
4874 do {
4875 claim = (nmethod*)_postponed_list;
4876 if (claim == NULL) {
4877 return NULL;
4878 }
4879
4880 next = claim->unloading_next();
4881
4882 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4883
4884 return claim;
4885 }
4886
4887 public:
4888 // Mark that we're done with the first pass of nmethod cleaning.
4889 void barrier_mark(uint worker_id) {
4890 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4891 _num_entered_barrier++;
4892 if (_num_entered_barrier == _num_workers) {
4893 ml.notify_all();
4894 }
4895 }
4896
4897 // See if we have to wait for the other workers to
4898 // finish their first-pass nmethod cleaning work.
4899 void barrier_wait(uint worker_id) {
4900 if (_num_entered_barrier < _num_workers) {
4901 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4902 while (_num_entered_barrier < _num_workers) {
4903 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4904 }
4905 }
4906 }
4907
4908 // Cleaning and unloading of nmethods. Some work has to be postponed
4909 // to the second pass, when we know which nmethods survive.
4910 void work_first_pass(uint worker_id) {
4911 // The first nmethods is claimed by the first worker.
4912 if (worker_id == 0 && _first_nmethod != NULL) {
4913 clean_nmethod(_first_nmethod);
4914 _first_nmethod = NULL;
4915 }
4916
4917 int num_claimed_nmethods;
4918 nmethod* claimed_nmethods[MaxClaimNmethods];
4919
4920 while (true) {
4921 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4922
4923 if (num_claimed_nmethods == 0) {
4924 break;
4925 }
4926
4927 for (int i = 0; i < num_claimed_nmethods; i++) {
4928 clean_nmethod(claimed_nmethods[i]);
4929 }
4930 }
4931 }
4932
4933 void work_second_pass(uint worker_id) {
4934 nmethod* nm;
4935 // Take care of postponed nmethods.
4936 while ((nm = claim_postponed_nmethod()) != NULL) {
4937 clean_nmethod_postponed(nm);
4938 }
4939 }
4940 };
4941
4942 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4943
4944 class G1KlassCleaningTask : public StackObj {
4945 BoolObjectClosure* _is_alive;
4946 volatile jint _clean_klass_tree_claimed;
4947 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4948
4949 public:
4950 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4951 _is_alive(is_alive),
4952 _clean_klass_tree_claimed(0),
4953 _klass_iterator() {
4954 }
4955
4956 private:
4957 bool claim_clean_klass_tree_task() {
4958 if (_clean_klass_tree_claimed) {
4959 return false;
4960 }
4961
4962 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4963 }
4964
4965 InstanceKlass* claim_next_klass() {
4966 Klass* klass;
4967 do {
4968 klass =_klass_iterator.next_klass();
4969 } while (klass != NULL && !klass->oop_is_instance());
4970
4971 return (InstanceKlass*)klass;
4972 }
4973
4974 public:
4975
4976 void clean_klass(InstanceKlass* ik) {
4977 ik->clean_weak_instanceklass_links(_is_alive);
4978 }
4979
4980 void work() {
4981 ResourceMark rm;
4982
4983 // One worker will clean the subklass/sibling klass tree.
4984 if (claim_clean_klass_tree_task()) {
4985 Klass::clean_subklass_tree(_is_alive);
4986 }
4987
4988 // All workers will help cleaning the classes,
4989 InstanceKlass* klass;
4990 while ((klass = claim_next_klass()) != NULL) {
4991 clean_klass(klass);
4992 }
4993 }
4994 };
4995
4996 // To minimize the remark pause times, the tasks below are done in parallel.
4997 class G1ParallelCleaningTask : public AbstractGangTask {
4998 private:
4999 G1StringSymbolTableUnlinkTask _string_symbol_task;
5000 G1CodeCacheUnloadingTask _code_cache_task;
5001 G1KlassCleaningTask _klass_cleaning_task;
5002
5003 public:
5004 // The constructor is run in the VMThread.
5005 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5006 AbstractGangTask("Parallel Cleaning"),
5007 _string_symbol_task(is_alive, process_strings, process_symbols),
5008 _code_cache_task(num_workers, is_alive, unloading_occurred),
5009 _klass_cleaning_task(is_alive) {
5010 }
5011
5012 // The parallel work done by all worker threads.
5013 void work(uint worker_id) {
5014 // Do first pass of code cache cleaning.
5015 _code_cache_task.work_first_pass(worker_id);
5016
5017 // Let the threads mark that the first pass is done.
5018 _code_cache_task.barrier_mark(worker_id);
5019
5020 // Clean the Strings and Symbols.
5021 _string_symbol_task.work(worker_id);
5022
5023 // Wait for all workers to finish the first code cache cleaning pass.
5024 _code_cache_task.barrier_wait(worker_id);
5025
5026 // Do the second code cache cleaning work, which realize on
5027 // the liveness information gathered during the first pass.
5028 _code_cache_task.work_second_pass(worker_id);
5029
5030 // Clean all klasses that were not unloaded.
5031 _klass_cleaning_task.work();
5032 }
5033 };
5034
5035
5036 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5037 bool process_strings,
5038 bool process_symbols,
5039 bool class_unloading_occurred) {
5040 uint n_workers = workers()->active_workers();
5041
5042 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5043 n_workers, class_unloading_occurred);
5044 workers()->run_task(&g1_unlink_task);
5045 }
5046
5047 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5048 bool process_strings, bool process_symbols) {
5049 {
5050 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5051 workers()->run_task(&g1_unlink_task);
5052 }
5053
5054 if (G1StringDedup::is_enabled()) {
5055 G1StringDedup::unlink(is_alive);
5056 }
5057 }
5058
5059 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5060 private:
5061 DirtyCardQueueSet* _queue;
5062 public:
5063 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5064
5065 virtual void work(uint worker_id) {
5066 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5067 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5068
5069 RedirtyLoggedCardTableEntryClosure cl;
5070 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5071
5072 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5073 }
5074 };
5075
5076 void G1CollectedHeap::redirty_logged_cards() {
5077 double redirty_logged_cards_start = os::elapsedTime();
5078
5079 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5080 dirty_card_queue_set().reset_for_par_iteration();
5081 workers()->run_task(&redirty_task);
5082
5083 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5084 dcq.merge_bufferlists(&dirty_card_queue_set());
5085 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5086
5087 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5088 }
5089
5090 // Weak Reference Processing support
5091
5092 // An always "is_alive" closure that is used to preserve referents.
5093 // If the object is non-null then it's alive. Used in the preservation
5094 // of referent objects that are pointed to by reference objects
5095 // discovered by the CM ref processor.
5096 class G1AlwaysAliveClosure: public BoolObjectClosure {
5097 G1CollectedHeap* _g1;
5098 public:
5099 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5100 bool do_object_b(oop p) {
5101 if (p != NULL) {
5102 return true;
5103 }
5104 return false;
5105 }
5106 };
5107
5108 bool G1STWIsAliveClosure::do_object_b(oop p) {
5109 // An object is reachable if it is outside the collection set,
5110 // or is inside and copied.
5111 return !_g1->is_in_cset(p) || p->is_forwarded();
5112 }
5113
5114 // Non Copying Keep Alive closure
5115 class G1KeepAliveClosure: public OopClosure {
5116 G1CollectedHeap* _g1;
5117 public:
5118 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5119 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5120 void do_oop(oop* p) {
5121 oop obj = *p;
5122 assert(obj != NULL, "the caller should have filtered out NULL values");
5123
5124 const InCSetState cset_state = _g1->in_cset_state(obj);
5125 if (!cset_state.is_in_cset_or_humongous()) {
5126 return;
5127 }
5128 if (cset_state.is_in_cset()) {
5129 assert( obj->is_forwarded(), "invariant" );
5130 *p = obj->forwardee();
5131 } else {
5132 assert(!obj->is_forwarded(), "invariant" );
5133 assert(cset_state.is_humongous(),
5134 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
5135 _g1->set_humongous_is_live(obj);
5136 }
5137 }
5138 };
5139
5140 // Copying Keep Alive closure - can be called from both
5141 // serial and parallel code as long as different worker
5142 // threads utilize different G1ParScanThreadState instances
5143 // and different queues.
5144
5145 class G1CopyingKeepAliveClosure: public OopClosure {
5146 G1CollectedHeap* _g1h;
5147 OopClosure* _copy_non_heap_obj_cl;
5148 G1ParScanThreadState* _par_scan_state;
5149
5150 public:
5151 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5152 OopClosure* non_heap_obj_cl,
5153 G1ParScanThreadState* pss):
5154 _g1h(g1h),
5155 _copy_non_heap_obj_cl(non_heap_obj_cl),
5156 _par_scan_state(pss)
5157 {}
5158
5159 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5160 virtual void do_oop( oop* p) { do_oop_work(p); }
5161
5162 template <class T> void do_oop_work(T* p) {
5163 oop obj = oopDesc::load_decode_heap_oop(p);
5164
5165 if (_g1h->is_in_cset_or_humongous(obj)) {
5166 // If the referent object has been forwarded (either copied
5167 // to a new location or to itself in the event of an
5168 // evacuation failure) then we need to update the reference
5169 // field and, if both reference and referent are in the G1
5170 // heap, update the RSet for the referent.
5171 //
5172 // If the referent has not been forwarded then we have to keep
5173 // it alive by policy. Therefore we have copy the referent.
5174 //
5175 // If the reference field is in the G1 heap then we can push
5176 // on the PSS queue. When the queue is drained (after each
5177 // phase of reference processing) the object and it's followers
5178 // will be copied, the reference field set to point to the
5179 // new location, and the RSet updated. Otherwise we need to
5180 // use the the non-heap or metadata closures directly to copy
5181 // the referent object and update the pointer, while avoiding
5182 // updating the RSet.
5183
5184 if (_g1h->is_in_g1_reserved(p)) {
5185 _par_scan_state->push_on_queue(p);
5186 } else {
5187 assert(!Metaspace::contains((const void*)p),
5188 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
5189 _copy_non_heap_obj_cl->do_oop(p);
5190 }
5191 }
5192 }
5193 };
5194
5195 // Serial drain queue closure. Called as the 'complete_gc'
5196 // closure for each discovered list in some of the
5197 // reference processing phases.
5198
5199 class G1STWDrainQueueClosure: public VoidClosure {
5200 protected:
5201 G1CollectedHeap* _g1h;
5202 G1ParScanThreadState* _par_scan_state;
5203
5204 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5205
5206 public:
5207 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5208 _g1h(g1h),
5209 _par_scan_state(pss)
5210 { }
5211
5212 void do_void() {
5213 G1ParScanThreadState* const pss = par_scan_state();
5214 pss->trim_queue();
5215 }
5216 };
5217
5218 // Parallel Reference Processing closures
5219
5220 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5221 // processing during G1 evacuation pauses.
5222
5223 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5224 private:
5225 G1CollectedHeap* _g1h;
5226 G1ParScanThreadStateSet* _pss;
5227 RefToScanQueueSet* _queues;
5228 WorkGang* _workers;
5229 uint _active_workers;
5230
5231 public:
5232 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5233 G1ParScanThreadStateSet* per_thread_states,
5234 WorkGang* workers,
5235 RefToScanQueueSet *task_queues,
5236 uint n_workers) :
5237 _g1h(g1h),
5238 _pss(per_thread_states),
5239 _queues(task_queues),
5240 _workers(workers),
5241 _active_workers(n_workers)
5242 {
5243 assert(n_workers > 0, "shouldn't call this otherwise");
5244 }
5245
5246 // Executes the given task using concurrent marking worker threads.
5247 virtual void execute(ProcessTask& task);
5248 virtual void execute(EnqueueTask& task);
5249 };
5250
5251 // Gang task for possibly parallel reference processing
5252
5253 class G1STWRefProcTaskProxy: public AbstractGangTask {
5254 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5255 ProcessTask& _proc_task;
5256 G1CollectedHeap* _g1h;
5257 G1ParScanThreadStateSet* _pss;
5258 RefToScanQueueSet* _task_queues;
5259 ParallelTaskTerminator* _terminator;
5260
5261 public:
5262 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5263 G1CollectedHeap* g1h,
5264 G1ParScanThreadStateSet* per_thread_states,
5265 RefToScanQueueSet *task_queues,
5266 ParallelTaskTerminator* terminator) :
5267 AbstractGangTask("Process reference objects in parallel"),
5268 _proc_task(proc_task),
5269 _g1h(g1h),
5270 _pss(per_thread_states),
5271 _task_queues(task_queues),
5272 _terminator(terminator)
5273 {}
5274
5275 virtual void work(uint worker_id) {
5276 // The reference processing task executed by a single worker.
5277 ResourceMark rm;
5278 HandleMark hm;
5279
5280 G1STWIsAliveClosure is_alive(_g1h);
5281
5282 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5283 pss->set_ref_processor(NULL);
5284
5285 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5286
5287 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5288
5289 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5290
5291 if (_g1h->collector_state()->during_initial_mark_pause()) {
5292 // We also need to mark copied objects.
5293 copy_non_heap_cl = ©_mark_non_heap_cl;
5294 }
5295
5296 // Keep alive closure.
5297 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5298
5299 // Complete GC closure
5300 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5301
5302 // Call the reference processing task's work routine.
5303 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5304
5305 // Note we cannot assert that the refs array is empty here as not all
5306 // of the processing tasks (specifically phase2 - pp2_work) execute
5307 // the complete_gc closure (which ordinarily would drain the queue) so
5308 // the queue may not be empty.
5309 }
5310 };
5311
5312 // Driver routine for parallel reference processing.
5313 // Creates an instance of the ref processing gang
5314 // task and has the worker threads execute it.
5315 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5316 assert(_workers != NULL, "Need parallel worker threads.");
5317
5318 ParallelTaskTerminator terminator(_active_workers, _queues);
5319 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5320
5321 _workers->run_task(&proc_task_proxy);
5322 }
5323
5324 // Gang task for parallel reference enqueueing.
5325
5326 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5327 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5328 EnqueueTask& _enq_task;
5329
5330 public:
5331 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5332 AbstractGangTask("Enqueue reference objects in parallel"),
5333 _enq_task(enq_task)
5334 { }
5335
5336 virtual void work(uint worker_id) {
5337 _enq_task.work(worker_id);
5338 }
5339 };
5340
5341 // Driver routine for parallel reference enqueueing.
5342 // Creates an instance of the ref enqueueing gang
5343 // task and has the worker threads execute it.
5344
5345 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5346 assert(_workers != NULL, "Need parallel worker threads.");
5347
5348 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5349
5350 _workers->run_task(&enq_task_proxy);
5351 }
5352
5353 // End of weak reference support closures
5354
5355 // Abstract task used to preserve (i.e. copy) any referent objects
5356 // that are in the collection set and are pointed to by reference
5357 // objects discovered by the CM ref processor.
5358
5359 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5360 protected:
5361 G1CollectedHeap* _g1h;
5362 G1ParScanThreadStateSet* _pss;
5363 RefToScanQueueSet* _queues;
5364 ParallelTaskTerminator _terminator;
5365 uint _n_workers;
5366
5367 public:
5368 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5369 AbstractGangTask("ParPreserveCMReferents"),
5370 _g1h(g1h),
5371 _pss(per_thread_states),
5372 _queues(task_queues),
5373 _terminator(workers, _queues),
5374 _n_workers(workers)
5375 { }
5376
5377 void work(uint worker_id) {
5378 ResourceMark rm;
5379 HandleMark hm;
5380
5381 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5382 pss->set_ref_processor(NULL);
5383 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5384
5385 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5386
5387 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5388
5389 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5390
5391 if (_g1h->collector_state()->during_initial_mark_pause()) {
5392 // We also need to mark copied objects.
5393 copy_non_heap_cl = ©_mark_non_heap_cl;
5394 }
5395
5396 // Is alive closure
5397 G1AlwaysAliveClosure always_alive(_g1h);
5398
5399 // Copying keep alive closure. Applied to referent objects that need
5400 // to be copied.
5401 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5402
5403 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5404
5405 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5406 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5407
5408 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5409 // So this must be true - but assert just in case someone decides to
5410 // change the worker ids.
5411 assert(worker_id < limit, "sanity");
5412 assert(!rp->discovery_is_atomic(), "check this code");
5413
5414 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5415 for (uint idx = worker_id; idx < limit; idx += stride) {
5416 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5417
5418 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5419 while (iter.has_next()) {
5420 // Since discovery is not atomic for the CM ref processor, we
5421 // can see some null referent objects.
5422 iter.load_ptrs(DEBUG_ONLY(true));
5423 oop ref = iter.obj();
5424
5425 // This will filter nulls.
5426 if (iter.is_referent_alive()) {
5427 iter.make_referent_alive();
5428 }
5429 iter.move_to_next();
5430 }
5431 }
5432
5433 // Drain the queue - which may cause stealing
5434 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5435 drain_queue.do_void();
5436 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5437 assert(pss->queue_is_empty(), "should be");
5438 }
5439 };
5440
5441 // Weak Reference processing during an evacuation pause (part 1).
5442 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5443 double ref_proc_start = os::elapsedTime();
5444
5445 ReferenceProcessor* rp = _ref_processor_stw;
5446 assert(rp->discovery_enabled(), "should have been enabled");
5447
5448 // Any reference objects, in the collection set, that were 'discovered'
5449 // by the CM ref processor should have already been copied (either by
5450 // applying the external root copy closure to the discovered lists, or
5451 // by following an RSet entry).
5452 //
5453 // But some of the referents, that are in the collection set, that these
5454 // reference objects point to may not have been copied: the STW ref
5455 // processor would have seen that the reference object had already
5456 // been 'discovered' and would have skipped discovering the reference,
5457 // but would not have treated the reference object as a regular oop.
5458 // As a result the copy closure would not have been applied to the
5459 // referent object.
5460 //
5461 // We need to explicitly copy these referent objects - the references
5462 // will be processed at the end of remarking.
5463 //
5464 // We also need to do this copying before we process the reference
5465 // objects discovered by the STW ref processor in case one of these
5466 // referents points to another object which is also referenced by an
5467 // object discovered by the STW ref processor.
5468
5469 uint no_of_gc_workers = workers()->active_workers();
5470
5471 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5472 per_thread_states,
5473 no_of_gc_workers,
5474 _task_queues);
5475
5476 workers()->run_task(&keep_cm_referents);
5477
5478 // Closure to test whether a referent is alive.
5479 G1STWIsAliveClosure is_alive(this);
5480
5481 // Even when parallel reference processing is enabled, the processing
5482 // of JNI refs is serial and performed serially by the current thread
5483 // rather than by a worker. The following PSS will be used for processing
5484 // JNI refs.
5485
5486 // Use only a single queue for this PSS.
5487 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5488 pss->set_ref_processor(NULL);
5489 assert(pss->queue_is_empty(), "pre-condition");
5490
5491 // We do not embed a reference processor in the copying/scanning
5492 // closures while we're actually processing the discovered
5493 // reference objects.
5494
5495 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss);
5496
5497 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5498
5499 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5500
5501 if (collector_state()->during_initial_mark_pause()) {
5502 // We also need to mark copied objects.
5503 copy_non_heap_cl = ©_mark_non_heap_cl;
5504 }
5505
5506 // Keep alive closure.
5507 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5508
5509 // Serial Complete GC closure
5510 G1STWDrainQueueClosure drain_queue(this, pss);
5511
5512 // Setup the soft refs policy...
5513 rp->setup_policy(false);
5514
5515 ReferenceProcessorStats stats;
5516 if (!rp->processing_is_mt()) {
5517 // Serial reference processing...
5518 stats = rp->process_discovered_references(&is_alive,
5519 &keep_alive,
5520 &drain_queue,
5521 NULL,
5522 _gc_timer_stw);
5523 } else {
5524 // Parallel reference processing
5525 assert(rp->num_q() == no_of_gc_workers, "sanity");
5526 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5527
5528 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5529 stats = rp->process_discovered_references(&is_alive,
5530 &keep_alive,
5531 &drain_queue,
5532 &par_task_executor,
5533 _gc_timer_stw);
5534 }
5535
5536 _gc_tracer_stw->report_gc_reference_stats(stats);
5537
5538 // We have completed copying any necessary live referent objects.
5539 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5540
5541 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5542 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5543 }
5544
5545 // Weak Reference processing during an evacuation pause (part 2).
5546 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5547 double ref_enq_start = os::elapsedTime();
5548
5549 ReferenceProcessor* rp = _ref_processor_stw;
5550 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5551
5552 // Now enqueue any remaining on the discovered lists on to
5553 // the pending list.
5554 if (!rp->processing_is_mt()) {
5555 // Serial reference processing...
5556 rp->enqueue_discovered_references();
5557 } else {
5558 // Parallel reference enqueueing
5559
5560 uint n_workers = workers()->active_workers();
5561
5562 assert(rp->num_q() == n_workers, "sanity");
5563 assert(n_workers <= rp->max_num_q(), "sanity");
5564
5565 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5566 rp->enqueue_discovered_references(&par_task_executor);
5567 }
5568
5569 rp->verify_no_references_recorded();
5570 assert(!rp->discovery_enabled(), "should have been disabled");
5571
5572 // FIXME
5573 // CM's reference processing also cleans up the string and symbol tables.
5574 // Should we do that here also? We could, but it is a serial operation
5575 // and could significantly increase the pause time.
5576
5577 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5578 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5579 }
5580
5581 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5582 _expand_heap_after_alloc_failure = true;
5583 _evacuation_failed = false;
5584
5585 // Should G1EvacuationFailureALot be in effect for this GC?
5586 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5587
5588 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5589
5590 // Disable the hot card cache.
5591 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5592 hot_card_cache->reset_hot_cache_claimed_index();
5593 hot_card_cache->set_use_cache(false);
5594
5595 const uint n_workers = workers()->active_workers();
5596
5597 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5598 double start_par_time_sec = os::elapsedTime();
5599 double end_par_time_sec;
5600
5601 {
5602 G1RootProcessor root_processor(this, n_workers);
5603 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5604 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5605 if (collector_state()->during_initial_mark_pause()) {
5606 ClassLoaderDataGraph::clear_claimed_marks();
5607 }
5608
5609 // The individual threads will set their evac-failure closures.
5610 if (PrintTerminationStats) {
5611 print_termination_stats_hdr(gclog_or_tty);
5612 }
5613
5614 workers()->run_task(&g1_par_task);
5615 end_par_time_sec = os::elapsedTime();
5616
5617 // Closing the inner scope will execute the destructor
5618 // for the G1RootProcessor object. We record the current
5619 // elapsed time before closing the scope so that time
5620 // taken for the destructor is NOT included in the
5621 // reported parallel time.
5622 }
5623
5624 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5625
5626 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5627 phase_times->record_par_time(par_time_ms);
5628
5629 double code_root_fixup_time_ms =
5630 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5631 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5632
5633 // Process any discovered reference objects - we have
5634 // to do this _before_ we retire the GC alloc regions
5635 // as we may have to copy some 'reachable' referent
5636 // objects (and their reachable sub-graphs) that were
5637 // not copied during the pause.
5638 process_discovered_references(per_thread_states);
5639
5640 if (G1StringDedup::is_enabled()) {
5641 double fixup_start = os::elapsedTime();
5642
5643 G1STWIsAliveClosure is_alive(this);
5644 G1KeepAliveClosure keep_alive(this);
5645 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5646
5647 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5648 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5649 }
5650
5651 _allocator->release_gc_alloc_regions(evacuation_info);
5652 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5653
5654 per_thread_states->flush();
5655
5656 record_obj_copy_mem_stats();
5657
5658 // Reset and re-enable the hot card cache.
5659 // Note the counts for the cards in the regions in the
5660 // collection set are reset when the collection set is freed.
5661 hot_card_cache->reset_hot_cache();
5662 hot_card_cache->set_use_cache(true);
5663
5664 purge_code_root_memory();
5665
5666 if (evacuation_failed()) {
5667 remove_self_forwarding_pointers();
5668
5669 // Reset the G1EvacuationFailureALot counters and flags
5670 // Note: the values are reset only when an actual
5671 // evacuation failure occurs.
5672 NOT_PRODUCT(reset_evacuation_should_fail();)
5673 }
5674
5675 // Enqueue any remaining references remaining on the STW
5676 // reference processor's discovered lists. We need to do
5677 // this after the card table is cleaned (and verified) as
5678 // the act of enqueueing entries on to the pending list
5679 // will log these updates (and dirty their associated
5680 // cards). We need these updates logged to update any
5681 // RSets.
5682 enqueue_discovered_references(per_thread_states);
5683
5684 redirty_logged_cards();
5685 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5686 }
5687
5688 void G1CollectedHeap::record_obj_copy_mem_stats() {
5689 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5690 create_g1_evac_summary(&_old_evac_stats));
5691 }
5692
5693 void G1CollectedHeap::free_region(HeapRegion* hr,
5694 FreeRegionList* free_list,
5695 bool par,
5696 bool locked) {
5697 assert(!hr->is_free(), "the region should not be free");
5698 assert(!hr->is_empty(), "the region should not be empty");
5699 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5700 assert(free_list != NULL, "pre-condition");
5701
5702 if (G1VerifyBitmaps) {
5703 MemRegion mr(hr->bottom(), hr->end());
5704 concurrent_mark()->clearRangePrevBitmap(mr);
5705 }
5706
5707 // Clear the card counts for this region.
5708 // Note: we only need to do this if the region is not young
5709 // (since we don't refine cards in young regions).
5710 if (!hr->is_young()) {
5711 _cg1r->hot_card_cache()->reset_card_counts(hr);
5712 }
5713 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5714 free_list->add_ordered(hr);
5715 }
5716
5717 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5718 FreeRegionList* free_list,
5719 bool par) {
5720 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5721 assert(free_list != NULL, "pre-condition");
5722
5723 size_t hr_capacity = hr->capacity();
5724 // We need to read this before we make the region non-humongous,
5725 // otherwise the information will be gone.
5726 uint last_index = hr->last_hc_index();
5727 hr->clear_humongous();
5728 free_region(hr, free_list, par);
5729
5730 uint i = hr->hrm_index() + 1;
5731 while (i < last_index) {
5732 HeapRegion* curr_hr = region_at(i);
5733 assert(curr_hr->is_continues_humongous(), "invariant");
5734 curr_hr->clear_humongous();
5735 free_region(curr_hr, free_list, par);
5736 i += 1;
5737 }
5738 }
5739
5740 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5741 const HeapRegionSetCount& humongous_regions_removed) {
5742 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5743 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5744 _old_set.bulk_remove(old_regions_removed);
5745 _humongous_set.bulk_remove(humongous_regions_removed);
5746 }
5747
5748 }
5749
5750 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5751 assert(list != NULL, "list can't be null");
5752 if (!list->is_empty()) {
5753 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5754 _hrm.insert_list_into_free_list(list);
5755 }
5756 }
5757
5758 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5759 decrease_used(bytes);
5760 }
5761
5762 class G1ParCleanupCTTask : public AbstractGangTask {
5763 G1SATBCardTableModRefBS* _ct_bs;
5764 G1CollectedHeap* _g1h;
5765 HeapRegion* volatile _su_head;
5766 public:
5767 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5768 G1CollectedHeap* g1h) :
5769 AbstractGangTask("G1 Par Cleanup CT Task"),
5770 _ct_bs(ct_bs), _g1h(g1h) { }
5771
5772 void work(uint worker_id) {
5773 HeapRegion* r;
5774 while (r = _g1h->pop_dirty_cards_region()) {
5775 clear_cards(r);
5776 }
5777 }
5778
5779 void clear_cards(HeapRegion* r) {
5780 // Cards of the survivors should have already been dirtied.
5781 if (!r->is_survivor()) {
5782 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5783 }
5784 }
5785 };
5786
5787 #ifndef PRODUCT
5788 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5789 G1CollectedHeap* _g1h;
5790 G1SATBCardTableModRefBS* _ct_bs;
5791 public:
5792 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5793 : _g1h(g1h), _ct_bs(ct_bs) { }
5794 virtual bool doHeapRegion(HeapRegion* r) {
5795 if (r->is_survivor()) {
5796 _g1h->verify_dirty_region(r);
5797 } else {
5798 _g1h->verify_not_dirty_region(r);
5799 }
5800 return false;
5801 }
5802 };
5803
5804 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5805 // All of the region should be clean.
5806 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5807 MemRegion mr(hr->bottom(), hr->end());
5808 ct_bs->verify_not_dirty_region(mr);
5809 }
5810
5811 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5812 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5813 // dirty allocated blocks as they allocate them. The thread that
5814 // retires each region and replaces it with a new one will do a
5815 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5816 // not dirty that area (one less thing to have to do while holding
5817 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5818 // is dirty.
5819 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5820 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5821 if (hr->is_young()) {
5822 ct_bs->verify_g1_young_region(mr);
5823 } else {
5824 ct_bs->verify_dirty_region(mr);
5825 }
5826 }
5827
5828 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5829 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5830 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5831 verify_dirty_region(hr);
5832 }
5833 }
5834
5835 void G1CollectedHeap::verify_dirty_young_regions() {
5836 verify_dirty_young_list(_young_list->first_region());
5837 }
5838
5839 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5840 HeapWord* tams, HeapWord* end) {
5841 guarantee(tams <= end,
5842 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5843 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5844 if (result < end) {
5845 gclog_or_tty->cr();
5846 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5847 bitmap_name, p2i(result));
5848 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5849 bitmap_name, p2i(tams), p2i(end));
5850 return false;
5851 }
5852 return true;
5853 }
5854
5855 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5856 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5857 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5858
5859 HeapWord* bottom = hr->bottom();
5860 HeapWord* ptams = hr->prev_top_at_mark_start();
5861 HeapWord* ntams = hr->next_top_at_mark_start();
5862 HeapWord* end = hr->end();
5863
5864 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5865
5866 bool res_n = true;
5867 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5868 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5869 // if we happen to be in that state.
5870 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5871 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5872 }
5873 if (!res_p || !res_n) {
5874 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5875 HR_FORMAT_PARAMS(hr));
5876 gclog_or_tty->print_cr("#### Caller: %s", caller);
5877 return false;
5878 }
5879 return true;
5880 }
5881
5882 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5883 if (!G1VerifyBitmaps) return;
5884
5885 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5886 }
5887
5888 class G1VerifyBitmapClosure : public HeapRegionClosure {
5889 private:
5890 const char* _caller;
5891 G1CollectedHeap* _g1h;
5892 bool _failures;
5893
5894 public:
5895 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5896 _caller(caller), _g1h(g1h), _failures(false) { }
5897
5898 bool failures() { return _failures; }
5899
5900 virtual bool doHeapRegion(HeapRegion* hr) {
5901 if (hr->is_continues_humongous()) return false;
5902
5903 bool result = _g1h->verify_bitmaps(_caller, hr);
5904 if (!result) {
5905 _failures = true;
5906 }
5907 return false;
5908 }
5909 };
5910
5911 void G1CollectedHeap::check_bitmaps(const char* caller) {
5912 if (!G1VerifyBitmaps) return;
5913
5914 G1VerifyBitmapClosure cl(caller, this);
5915 heap_region_iterate(&cl);
5916 guarantee(!cl.failures(), "bitmap verification");
5917 }
5918
5919 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5920 private:
5921 bool _failures;
5922 public:
5923 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5924
5925 virtual bool doHeapRegion(HeapRegion* hr) {
5926 uint i = hr->hrm_index();
5927 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5928 if (hr->is_humongous()) {
5929 if (hr->in_collection_set()) {
5930 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5931 _failures = true;
5932 return true;
5933 }
5934 if (cset_state.is_in_cset()) {
5935 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5936 _failures = true;
5937 return true;
5938 }
5939 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5940 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5941 _failures = true;
5942 return true;
5943 }
5944 } else {
5945 if (cset_state.is_humongous()) {
5946 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5947 _failures = true;
5948 return true;
5949 }
5950 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5951 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5952 hr->in_collection_set(), cset_state.value(), i);
5953 _failures = true;
5954 return true;
5955 }
5956 if (cset_state.is_in_cset()) {
5957 if (hr->is_young() != (cset_state.is_young())) {
5958 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5959 hr->is_young(), cset_state.value(), i);
5960 _failures = true;
5961 return true;
5962 }
5963 if (hr->is_old() != (cset_state.is_old())) {
5964 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5965 hr->is_old(), cset_state.value(), i);
5966 _failures = true;
5967 return true;
5968 }
5969 }
5970 }
5971 return false;
5972 }
5973
5974 bool failures() const { return _failures; }
5975 };
5976
5977 bool G1CollectedHeap::check_cset_fast_test() {
5978 G1CheckCSetFastTableClosure cl;
5979 _hrm.iterate(&cl);
5980 return !cl.failures();
5981 }
5982 #endif // PRODUCT
5983
5984 void G1CollectedHeap::cleanUpCardTable() {
5985 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5986 double start = os::elapsedTime();
5987
5988 {
5989 // Iterate over the dirty cards region list.
5990 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5991
5992 workers()->run_task(&cleanup_task);
5993 #ifndef PRODUCT
5994 if (G1VerifyCTCleanup || VerifyAfterGC) {
5995 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5996 heap_region_iterate(&cleanup_verifier);
5997 }
5998 #endif
5999 }
6000
6001 double elapsed = os::elapsedTime() - start;
6002 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6003 }
6004
6005 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
6006 size_t pre_used = 0;
6007 FreeRegionList local_free_list("Local List for CSet Freeing");
6008
6009 double young_time_ms = 0.0;
6010 double non_young_time_ms = 0.0;
6011
6012 // Since the collection set is a superset of the the young list,
6013 // all we need to do to clear the young list is clear its
6014 // head and length, and unlink any young regions in the code below
6015 _young_list->clear();
6016
6017 G1CollectorPolicy* policy = g1_policy();
6018
6019 double start_sec = os::elapsedTime();
6020 bool non_young = true;
6021
6022 HeapRegion* cur = cs_head;
6023 int age_bound = -1;
6024 size_t rs_lengths = 0;
6025
6026 while (cur != NULL) {
6027 assert(!is_on_master_free_list(cur), "sanity");
6028 if (non_young) {
6029 if (cur->is_young()) {
6030 double end_sec = os::elapsedTime();
6031 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6032 non_young_time_ms += elapsed_ms;
6033
6034 start_sec = os::elapsedTime();
6035 non_young = false;
6036 }
6037 } else {
6038 if (!cur->is_young()) {
6039 double end_sec = os::elapsedTime();
6040 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6041 young_time_ms += elapsed_ms;
6042
6043 start_sec = os::elapsedTime();
6044 non_young = true;
6045 }
6046 }
6047
6048 rs_lengths += cur->rem_set()->occupied_locked();
6049
6050 HeapRegion* next = cur->next_in_collection_set();
6051 assert(cur->in_collection_set(), "bad CS");
6052 cur->set_next_in_collection_set(NULL);
6053 clear_in_cset(cur);
6054
6055 if (cur->is_young()) {
6056 int index = cur->young_index_in_cset();
6057 assert(index != -1, "invariant");
6058 assert((uint) index < policy->young_cset_region_length(), "invariant");
6059 size_t words_survived = surviving_young_words[index];
6060 cur->record_surv_words_in_group(words_survived);
6061
6062 // At this point the we have 'popped' cur from the collection set
6063 // (linked via next_in_collection_set()) but it is still in the
6064 // young list (linked via next_young_region()). Clear the
6065 // _next_young_region field.
6066 cur->set_next_young_region(NULL);
6067 } else {
6068 int index = cur->young_index_in_cset();
6069 assert(index == -1, "invariant");
6070 }
6071
6072 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6073 (!cur->is_young() && cur->young_index_in_cset() == -1),
6074 "invariant" );
6075
6076 if (!cur->evacuation_failed()) {
6077 MemRegion used_mr = cur->used_region();
6078
6079 // And the region is empty.
6080 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6081 pre_used += cur->used();
6082 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6083 } else {
6084 cur->uninstall_surv_rate_group();
6085 if (cur->is_young()) {
6086 cur->set_young_index_in_cset(-1);
6087 }
6088 cur->set_evacuation_failed(false);
6089 // The region is now considered to be old.
6090 cur->set_old();
6091 // Do some allocation statistics accounting. Regions that failed evacuation
6092 // are always made old, so there is no need to update anything in the young
6093 // gen statistics, but we need to update old gen statistics.
6094 size_t used_words = cur->marked_bytes() / HeapWordSize;
6095 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6096 _old_set.add(cur);
6097 evacuation_info.increment_collectionset_used_after(cur->used());
6098 }
6099 cur = next;
6100 }
6101
6102 evacuation_info.set_regions_freed(local_free_list.length());
6103 policy->record_max_rs_lengths(rs_lengths);
6104 policy->cset_regions_freed();
6105
6106 double end_sec = os::elapsedTime();
6107 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6108
6109 if (non_young) {
6110 non_young_time_ms += elapsed_ms;
6111 } else {
6112 young_time_ms += elapsed_ms;
6113 }
6114
6115 prepend_to_freelist(&local_free_list);
6116 decrement_summary_bytes(pre_used);
6117 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6118 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6119 }
6120
6121 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6122 private:
6123 FreeRegionList* _free_region_list;
6124 HeapRegionSet* _proxy_set;
6125 HeapRegionSetCount _humongous_regions_removed;
6126 size_t _freed_bytes;
6127 public:
6128
6129 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6130 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6131 }
6132
6133 virtual bool doHeapRegion(HeapRegion* r) {
6134 if (!r->is_starts_humongous()) {
6135 return false;
6136 }
6137
6138 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6139
6140 oop obj = (oop)r->bottom();
6141 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6142
6143 // The following checks whether the humongous object is live are sufficient.
6144 // The main additional check (in addition to having a reference from the roots
6145 // or the young gen) is whether the humongous object has a remembered set entry.
6146 //
6147 // A humongous object cannot be live if there is no remembered set for it
6148 // because:
6149 // - there can be no references from within humongous starts regions referencing
6150 // the object because we never allocate other objects into them.
6151 // (I.e. there are no intra-region references that may be missed by the
6152 // remembered set)
6153 // - as soon there is a remembered set entry to the humongous starts region
6154 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6155 // until the end of a concurrent mark.
6156 //
6157 // It is not required to check whether the object has been found dead by marking
6158 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6159 // all objects allocated during that time are considered live.
6160 // SATB marking is even more conservative than the remembered set.
6161 // So if at this point in the collection there is no remembered set entry,
6162 // nobody has a reference to it.
6163 // At the start of collection we flush all refinement logs, and remembered sets
6164 // are completely up-to-date wrt to references to the humongous object.
6165 //
6166 // Other implementation considerations:
6167 // - never consider object arrays at this time because they would pose
6168 // considerable effort for cleaning up the the remembered sets. This is
6169 // required because stale remembered sets might reference locations that
6170 // are currently allocated into.
6171 uint region_idx = r->hrm_index();
6172 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6173 !r->rem_set()->is_empty()) {
6174
6175 if (G1TraceEagerReclaimHumongousObjects) {
6176 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",
6177 region_idx,
6178 (size_t)obj->size() * HeapWordSize,
6179 p2i(r->bottom()),
6180 r->region_num(),
6181 r->rem_set()->occupied(),
6182 r->rem_set()->strong_code_roots_list_length(),
6183 next_bitmap->isMarked(r->bottom()),
6184 g1h->is_humongous_reclaim_candidate(region_idx),
6185 obj->is_typeArray()
6186 );
6187 }
6188
6189 return false;
6190 }
6191
6192 guarantee(obj->is_typeArray(),
6193 "Only eagerly reclaiming type arrays is supported, but the object "
6194 PTR_FORMAT " is not.", p2i(r->bottom()));
6195
6196 if (G1TraceEagerReclaimHumongousObjects) {
6197 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",
6198 region_idx,
6199 (size_t)obj->size() * HeapWordSize,
6200 p2i(r->bottom()),
6201 r->region_num(),
6202 r->rem_set()->occupied(),
6203 r->rem_set()->strong_code_roots_list_length(),
6204 next_bitmap->isMarked(r->bottom()),
6205 g1h->is_humongous_reclaim_candidate(region_idx),
6206 obj->is_typeArray()
6207 );
6208 }
6209 // Need to clear mark bit of the humongous object if already set.
6210 if (next_bitmap->isMarked(r->bottom())) {
6211 next_bitmap->clear(r->bottom());
6212 }
6213 _freed_bytes += r->used();
6214 r->set_containing_set(NULL);
6215 _humongous_regions_removed.increment(1u, r->capacity());
6216 g1h->free_humongous_region(r, _free_region_list, false);
6217
6218 return false;
6219 }
6220
6221 HeapRegionSetCount& humongous_free_count() {
6222 return _humongous_regions_removed;
6223 }
6224
6225 size_t bytes_freed() const {
6226 return _freed_bytes;
6227 }
6228
6229 size_t humongous_reclaimed() const {
6230 return _humongous_regions_removed.length();
6231 }
6232 };
6233
6234 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6235 assert_at_safepoint(true);
6236
6237 if (!G1EagerReclaimHumongousObjects ||
6238 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6239 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6240 return;
6241 }
6242
6243 double start_time = os::elapsedTime();
6244
6245 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6246
6247 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6248 heap_region_iterate(&cl);
6249
6250 HeapRegionSetCount empty_set;
6251 remove_from_old_sets(empty_set, cl.humongous_free_count());
6252
6253 G1HRPrinter* hrp = hr_printer();
6254 if (hrp->is_active()) {
6255 FreeRegionListIterator iter(&local_cleanup_list);
6256 while (iter.more_available()) {
6257 HeapRegion* hr = iter.get_next();
6258 hrp->cleanup(hr);
6259 }
6260 }
6261
6262 prepend_to_freelist(&local_cleanup_list);
6263 decrement_summary_bytes(cl.bytes_freed());
6264
6265 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6266 cl.humongous_reclaimed());
6267 }
6268
6269 // This routine is similar to the above but does not record
6270 // any policy statistics or update free lists; we are abandoning
6271 // the current incremental collection set in preparation of a
6272 // full collection. After the full GC we will start to build up
6273 // the incremental collection set again.
6274 // This is only called when we're doing a full collection
6275 // and is immediately followed by the tearing down of the young list.
6276
6277 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6278 HeapRegion* cur = cs_head;
6279
6280 while (cur != NULL) {
6281 HeapRegion* next = cur->next_in_collection_set();
6282 assert(cur->in_collection_set(), "bad CS");
6283 cur->set_next_in_collection_set(NULL);
6284 clear_in_cset(cur);
6285 cur->set_young_index_in_cset(-1);
6286 cur = next;
6287 }
6288 }
6289
6290 void G1CollectedHeap::set_free_regions_coming() {
6291 if (G1ConcRegionFreeingVerbose) {
6292 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6293 "setting free regions coming");
6294 }
6295
6296 assert(!free_regions_coming(), "pre-condition");
6297 _free_regions_coming = true;
6298 }
6299
6300 void G1CollectedHeap::reset_free_regions_coming() {
6301 assert(free_regions_coming(), "pre-condition");
6302
6303 {
6304 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6305 _free_regions_coming = false;
6306 SecondaryFreeList_lock->notify_all();
6307 }
6308
6309 if (G1ConcRegionFreeingVerbose) {
6310 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6311 "reset free regions coming");
6312 }
6313 }
6314
6315 void G1CollectedHeap::wait_while_free_regions_coming() {
6316 // Most of the time we won't have to wait, so let's do a quick test
6317 // first before we take the lock.
6318 if (!free_regions_coming()) {
6319 return;
6320 }
6321
6322 if (G1ConcRegionFreeingVerbose) {
6323 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6324 "waiting for free regions");
6325 }
6326
6327 {
6328 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6329 while (free_regions_coming()) {
6330 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6331 }
6332 }
6333
6334 if (G1ConcRegionFreeingVerbose) {
6335 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6336 "done waiting for free regions");
6337 }
6338 }
6339
6340 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6341 return _allocator->is_retained_old_region(hr);
6342 }
6343
6344 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6345 _young_list->push_region(hr);
6346 }
6347
6348 class NoYoungRegionsClosure: public HeapRegionClosure {
6349 private:
6350 bool _success;
6351 public:
6352 NoYoungRegionsClosure() : _success(true) { }
6353 bool doHeapRegion(HeapRegion* r) {
6354 if (r->is_young()) {
6355 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6356 p2i(r->bottom()), p2i(r->end()));
6357 _success = false;
6358 }
6359 return false;
6360 }
6361 bool success() { return _success; }
6362 };
6363
6364 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6365 bool ret = _young_list->check_list_empty(check_sample);
6366
6367 if (check_heap) {
6368 NoYoungRegionsClosure closure;
6369 heap_region_iterate(&closure);
6370 ret = ret && closure.success();
6371 }
6372
6373 return ret;
6374 }
6375
6376 class TearDownRegionSetsClosure : public HeapRegionClosure {
6377 private:
6378 HeapRegionSet *_old_set;
6379
6380 public:
6381 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6382
6383 bool doHeapRegion(HeapRegion* r) {
6384 if (r->is_old()) {
6385 _old_set->remove(r);
6386 } else {
6387 // We ignore free regions, we'll empty the free list afterwards.
6388 // We ignore young regions, we'll empty the young list afterwards.
6389 // We ignore humongous regions, we're not tearing down the
6390 // humongous regions set.
6391 assert(r->is_free() || r->is_young() || r->is_humongous(),
6392 "it cannot be another type");
6393 }
6394 return false;
6395 }
6396
6397 ~TearDownRegionSetsClosure() {
6398 assert(_old_set->is_empty(), "post-condition");
6399 }
6400 };
6401
6402 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6403 assert_at_safepoint(true /* should_be_vm_thread */);
6404
6405 if (!free_list_only) {
6406 TearDownRegionSetsClosure cl(&_old_set);
6407 heap_region_iterate(&cl);
6408
6409 // Note that emptying the _young_list is postponed and instead done as
6410 // the first step when rebuilding the regions sets again. The reason for
6411 // this is that during a full GC string deduplication needs to know if
6412 // a collected region was young or old when the full GC was initiated.
6413 }
6414 _hrm.remove_all_free_regions();
6415 }
6416
6417 void G1CollectedHeap::increase_used(size_t bytes) {
6418 _summary_bytes_used += bytes;
6419 }
6420
6421 void G1CollectedHeap::decrease_used(size_t bytes) {
6422 assert(_summary_bytes_used >= bytes,
6423 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6424 _summary_bytes_used, bytes);
6425 _summary_bytes_used -= bytes;
6426 }
6427
6428 void G1CollectedHeap::set_used(size_t bytes) {
6429 _summary_bytes_used = bytes;
6430 }
6431
6432 class RebuildRegionSetsClosure : public HeapRegionClosure {
6433 private:
6434 bool _free_list_only;
6435 HeapRegionSet* _old_set;
6436 HeapRegionManager* _hrm;
6437 size_t _total_used;
6438
6439 public:
6440 RebuildRegionSetsClosure(bool free_list_only,
6441 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6442 _free_list_only(free_list_only),
6443 _old_set(old_set), _hrm(hrm), _total_used(0) {
6444 assert(_hrm->num_free_regions() == 0, "pre-condition");
6445 if (!free_list_only) {
6446 assert(_old_set->is_empty(), "pre-condition");
6447 }
6448 }
6449
6450 bool doHeapRegion(HeapRegion* r) {
6451 if (r->is_continues_humongous()) {
6452 return false;
6453 }
6454
6455 if (r->is_empty()) {
6456 // Add free regions to the free list
6457 r->set_free();
6458 r->set_allocation_context(AllocationContext::system());
6459 _hrm->insert_into_free_list(r);
6460 } else if (!_free_list_only) {
6461 assert(!r->is_young(), "we should not come across young regions");
6462
6463 if (r->is_humongous()) {
6464 // We ignore humongous regions. We left the humongous set unchanged.
6465 } else {
6466 // Objects that were compacted would have ended up on regions
6467 // that were previously old or free. Archive regions (which are
6468 // old) will not have been touched.
6469 assert(r->is_free() || r->is_old(), "invariant");
6470 // We now consider them old, so register as such. Leave
6471 // archive regions set that way, however, while still adding
6472 // them to the old set.
6473 if (!r->is_archive()) {
6474 r->set_old();
6475 }
6476 _old_set->add(r);
6477 }
6478 _total_used += r->used();
6479 }
6480
6481 return false;
6482 }
6483
6484 size_t total_used() {
6485 return _total_used;
6486 }
6487 };
6488
6489 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6490 assert_at_safepoint(true /* should_be_vm_thread */);
6491
6492 if (!free_list_only) {
6493 _young_list->empty_list();
6494 }
6495
6496 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6497 heap_region_iterate(&cl);
6498
6499 if (!free_list_only) {
6500 set_used(cl.total_used());
6501 if (_archive_allocator != NULL) {
6502 _archive_allocator->clear_used();
6503 }
6504 }
6505 assert(used_unlocked() == recalculate_used(),
6506 "inconsistent used_unlocked(), "
6507 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6508 used_unlocked(), recalculate_used());
6509 }
6510
6511 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6512 _refine_cte_cl->set_concurrent(concurrent);
6513 }
6514
6515 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6516 HeapRegion* hr = heap_region_containing(p);
6517 return hr->is_in(p);
6518 }
6519
6520 // Methods for the mutator alloc region
6521
6522 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6523 bool force) {
6524 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6525 assert(!force || g1_policy()->can_expand_young_list(),
6526 "if force is true we should be able to expand the young list");
6527 bool young_list_full = g1_policy()->is_young_list_full();
6528 if (force || !young_list_full) {
6529 HeapRegion* new_alloc_region = new_region(word_size,
6530 false /* is_old */,
6531 false /* do_expand */);
6532 if (new_alloc_region != NULL) {
6533 set_region_short_lived_locked(new_alloc_region);
6534 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6535 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6536 return new_alloc_region;
6537 }
6538 }
6539 return NULL;
6540 }
6541
6542 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6543 size_t allocated_bytes) {
6544 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6545 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6546
6547 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6548 increase_used(allocated_bytes);
6549 _hr_printer.retire(alloc_region);
6550 // We update the eden sizes here, when the region is retired,
6551 // instead of when it's allocated, since this is the point that its
6552 // used space has been recored in _summary_bytes_used.
6553 g1mm()->update_eden_size();
6554 }
6555
6556 // Methods for the GC alloc regions
6557
6558 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6559 uint count,
6560 InCSetState dest) {
6561 assert(FreeList_lock->owned_by_self(), "pre-condition");
6562
6563 if (count < g1_policy()->max_regions(dest)) {
6564 const bool is_survivor = (dest.is_young());
6565 HeapRegion* new_alloc_region = new_region(word_size,
6566 !is_survivor,
6567 true /* do_expand */);
6568 if (new_alloc_region != NULL) {
6569 // We really only need to do this for old regions given that we
6570 // should never scan survivors. But it doesn't hurt to do it
6571 // for survivors too.
6572 new_alloc_region->record_timestamp();
6573 if (is_survivor) {
6574 new_alloc_region->set_survivor();
6575 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6576 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6577 } else {
6578 new_alloc_region->set_old();
6579 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6580 check_bitmaps("Old Region Allocation", new_alloc_region);
6581 }
6582 bool during_im = collector_state()->during_initial_mark_pause();
6583 new_alloc_region->note_start_of_copying(during_im);
6584 return new_alloc_region;
6585 }
6586 }
6587 return NULL;
6588 }
6589
6590 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6591 size_t allocated_bytes,
6592 InCSetState dest) {
6593 bool during_im = collector_state()->during_initial_mark_pause();
6594 alloc_region->note_end_of_copying(during_im);
6595 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6596 if (dest.is_young()) {
6597 young_list()->add_survivor_region(alloc_region);
6598 } else {
6599 _old_set.add(alloc_region);
6600 }
6601 _hr_printer.retire(alloc_region);
6602 }
6603
6604 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6605 bool expanded = false;
6606 uint index = _hrm.find_highest_free(&expanded);
6607
6608 if (index != G1_NO_HRM_INDEX) {
6609 if (expanded) {
6610 ergo_verbose1(ErgoHeapSizing,
6611 "attempt heap expansion",
6612 ergo_format_reason("requested address range outside heap bounds")
6613 ergo_format_byte("region size"),
6614 HeapRegion::GrainWords * HeapWordSize);
6615 }
6616 _hrm.allocate_free_regions_starting_at(index, 1);
6617 return region_at(index);
6618 }
6619 return NULL;
6620 }
6621
6622 // Heap region set verification
6623
6624 class VerifyRegionListsClosure : public HeapRegionClosure {
6625 private:
6626 HeapRegionSet* _old_set;
6627 HeapRegionSet* _humongous_set;
6628 HeapRegionManager* _hrm;
6629
6630 public:
6631 HeapRegionSetCount _old_count;
6632 HeapRegionSetCount _humongous_count;
6633 HeapRegionSetCount _free_count;
6634
6635 VerifyRegionListsClosure(HeapRegionSet* old_set,
6636 HeapRegionSet* humongous_set,
6637 HeapRegionManager* hrm) :
6638 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6639 _old_count(), _humongous_count(), _free_count(){ }
6640
6641 bool doHeapRegion(HeapRegion* hr) {
6642 if (hr->is_continues_humongous()) {
6643 return false;
6644 }
6645
6646 if (hr->is_young()) {
6647 // TODO
6648 } else if (hr->is_starts_humongous()) {
6649 assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index());
6650 _humongous_count.increment(1u, hr->capacity());
6651 } else if (hr->is_empty()) {
6652 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6653 _free_count.increment(1u, hr->capacity());
6654 } else if (hr->is_old()) {
6655 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6656 _old_count.increment(1u, hr->capacity());
6657 } else {
6658 // There are no other valid region types. Check for one invalid
6659 // one we can identify: pinned without old or humongous set.
6660 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6661 ShouldNotReachHere();
6662 }
6663 return false;
6664 }
6665
6666 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6667 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6668 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6669 old_set->total_capacity_bytes(), _old_count.capacity());
6670
6671 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6672 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6673 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6674
6675 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6676 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6677 free_list->total_capacity_bytes(), _free_count.capacity());
6678 }
6679 };
6680
6681 void G1CollectedHeap::verify_region_sets() {
6682 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6683
6684 // First, check the explicit lists.
6685 _hrm.verify();
6686 {
6687 // Given that a concurrent operation might be adding regions to
6688 // the secondary free list we have to take the lock before
6689 // verifying it.
6690 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6691 _secondary_free_list.verify_list();
6692 }
6693
6694 // If a concurrent region freeing operation is in progress it will
6695 // be difficult to correctly attributed any free regions we come
6696 // across to the correct free list given that they might belong to
6697 // one of several (free_list, secondary_free_list, any local lists,
6698 // etc.). So, if that's the case we will skip the rest of the
6699 // verification operation. Alternatively, waiting for the concurrent
6700 // operation to complete will have a non-trivial effect on the GC's
6701 // operation (no concurrent operation will last longer than the
6702 // interval between two calls to verification) and it might hide
6703 // any issues that we would like to catch during testing.
6704 if (free_regions_coming()) {
6705 return;
6706 }
6707
6708 // Make sure we append the secondary_free_list on the free_list so
6709 // that all free regions we will come across can be safely
6710 // attributed to the free_list.
6711 append_secondary_free_list_if_not_empty_with_lock();
6712
6713 // Finally, make sure that the region accounting in the lists is
6714 // consistent with what we see in the heap.
6715
6716 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6717 heap_region_iterate(&cl);
6718 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6719 }
6720
6721 // Optimized nmethod scanning
6722
6723 class RegisterNMethodOopClosure: public OopClosure {
6724 G1CollectedHeap* _g1h;
6725 nmethod* _nm;
6726
6727 template <class T> void do_oop_work(T* p) {
6728 T heap_oop = oopDesc::load_heap_oop(p);
6729 if (!oopDesc::is_null(heap_oop)) {
6730 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6731 HeapRegion* hr = _g1h->heap_region_containing(obj);
6732 assert(!hr->is_continues_humongous(),
6733 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6734 " starting at " HR_FORMAT,
6735 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6736
6737 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6738 hr->add_strong_code_root_locked(_nm);
6739 }
6740 }
6741
6742 public:
6743 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6744 _g1h(g1h), _nm(nm) {}
6745
6746 void do_oop(oop* p) { do_oop_work(p); }
6747 void do_oop(narrowOop* p) { do_oop_work(p); }
6748 };
6749
6750 class UnregisterNMethodOopClosure: public OopClosure {
6751 G1CollectedHeap* _g1h;
6752 nmethod* _nm;
6753
6754 template <class T> void do_oop_work(T* p) {
6755 T heap_oop = oopDesc::load_heap_oop(p);
6756 if (!oopDesc::is_null(heap_oop)) {
6757 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6758 HeapRegion* hr = _g1h->heap_region_containing(obj);
6759 assert(!hr->is_continues_humongous(),
6760 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6761 " starting at " HR_FORMAT,
6762 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6763
6764 hr->remove_strong_code_root(_nm);
6765 }
6766 }
6767
6768 public:
6769 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6770 _g1h(g1h), _nm(nm) {}
6771
6772 void do_oop(oop* p) { do_oop_work(p); }
6773 void do_oop(narrowOop* p) { do_oop_work(p); }
6774 };
6775
6776 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6777 CollectedHeap::register_nmethod(nm);
6778
6779 guarantee(nm != NULL, "sanity");
6780 RegisterNMethodOopClosure reg_cl(this, nm);
6781 nm->oops_do(®_cl);
6782 }
6783
6784 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6785 CollectedHeap::unregister_nmethod(nm);
6786
6787 guarantee(nm != NULL, "sanity");
6788 UnregisterNMethodOopClosure reg_cl(this, nm);
6789 nm->oops_do(®_cl, true);
6790 }
6791
6792 void G1CollectedHeap::purge_code_root_memory() {
6793 double purge_start = os::elapsedTime();
6794 G1CodeRootSet::purge();
6795 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6796 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6797 }
6798
6799 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6800 G1CollectedHeap* _g1h;
6801
6802 public:
6803 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6804 _g1h(g1h) {}
6805
6806 void do_code_blob(CodeBlob* cb) {
6807 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6808 if (nm == NULL) {
6809 return;
6810 }
6811
6812 if (ScavengeRootsInCode) {
6813 _g1h->register_nmethod(nm);
6814 }
6815 }
6816 };
6817
6818 void G1CollectedHeap::rebuild_strong_code_roots() {
6819 RebuildStrongCodeRootClosure blob_cl(this);
6820 CodeCache::blobs_do(&blob_cl);
6821 }