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/g1RootClosures.hpp"
48 #include "gc/g1/g1RootProcessor.hpp"
49 #include "gc/g1/g1StringDedup.hpp"
50 #include "gc/g1/g1YCTypes.hpp"
51 #include "gc/g1/heapRegion.inline.hpp"
52 #include "gc/g1/heapRegionRemSet.hpp"
53 #include "gc/g1/heapRegionSet.inline.hpp"
54 #include "gc/g1/suspendibleThreadSet.hpp"
55 #include "gc/g1/vm_operations_g1.hpp"
56 #include "gc/shared/gcHeapSummary.hpp"
57 #include "gc/shared/gcId.hpp"
58 #include "gc/shared/gcLocker.inline.hpp"
59 #include "gc/shared/gcTimer.hpp"
60 #include "gc/shared/gcTrace.hpp"
61 #include "gc/shared/gcTraceTime.hpp"
62 #include "gc/shared/generationSpec.hpp"
63 #include "gc/shared/isGCActiveMark.hpp"
64 #include "gc/shared/referenceProcessor.hpp"
65 #include "gc/shared/taskqueue.inline.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_processed;
116
117 public:
118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
119
120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
121 *card_ptr = CardTableModRefBS::dirty_card_val();
122 _num_processed++;
123 return true;
124 }
125
126 size_t num_processed() const { return _num_processed; }
127 };
128
129 YoungList::YoungList(G1CollectedHeap* g1h) :
130 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
131 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
132 guarantee(check_list_empty(false), "just making sure...");
133 }
134
135 void YoungList::push_region(HeapRegion *hr) {
136 assert(!hr->is_young(), "should not already be young");
137 assert(hr->get_next_young_region() == NULL, "cause it should!");
138
139 hr->set_next_young_region(_head);
140 _head = hr;
141
142 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
143 ++_length;
144 }
145
146 void YoungList::add_survivor_region(HeapRegion* hr) {
147 assert(hr->is_survivor(), "should be flagged as survivor region");
148 assert(hr->get_next_young_region() == NULL, "cause it should!");
149
150 hr->set_next_young_region(_survivor_head);
151 if (_survivor_head == NULL) {
152 _survivor_tail = hr;
153 }
154 _survivor_head = hr;
155 ++_survivor_length;
156 }
157
158 void YoungList::empty_list(HeapRegion* list) {
159 while (list != NULL) {
160 HeapRegion* next = list->get_next_young_region();
161 list->set_next_young_region(NULL);
162 list->uninstall_surv_rate_group();
163 // This is called before a Full GC and all the non-empty /
164 // non-humongous regions at the end of the Full GC will end up as
165 // old anyway.
166 list->set_old();
167 list = next;
168 }
169 }
170
171 void YoungList::empty_list() {
172 assert(check_list_well_formed(), "young list should be well formed");
173
174 empty_list(_head);
175 _head = NULL;
176 _length = 0;
177
178 empty_list(_survivor_head);
179 _survivor_head = NULL;
180 _survivor_tail = NULL;
181 _survivor_length = 0;
182
183 _last_sampled_rs_lengths = 0;
184
185 assert(check_list_empty(false), "just making sure...");
186 }
187
188 bool YoungList::check_list_well_formed() {
189 bool ret = true;
190
191 uint length = 0;
192 HeapRegion* curr = _head;
193 HeapRegion* last = NULL;
194 while (curr != NULL) {
195 if (!curr->is_young()) {
196 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
197 "incorrectly tagged (y: %d, surv: %d)",
198 p2i(curr->bottom()), p2i(curr->end()),
199 curr->is_young(), curr->is_survivor());
200 ret = false;
201 }
202 ++length;
203 last = curr;
204 curr = curr->get_next_young_region();
205 }
206 ret = ret && (length == _length);
207
208 if (!ret) {
209 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
210 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
211 length, _length);
212 }
213
214 return ret;
215 }
216
217 bool YoungList::check_list_empty(bool check_sample) {
218 bool ret = true;
219
220 if (_length != 0) {
221 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
222 _length);
223 ret = false;
224 }
225 if (check_sample && _last_sampled_rs_lengths != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
227 ret = false;
228 }
229 if (_head != NULL) {
230 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
231 ret = false;
232 }
233 if (!ret) {
234 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
235 }
236
237 return ret;
238 }
239
240 void
241 YoungList::rs_length_sampling_init() {
242 _sampled_rs_lengths = 0;
243 _curr = _head;
244 }
245
246 bool
247 YoungList::rs_length_sampling_more() {
248 return _curr != NULL;
249 }
250
251 void
252 YoungList::rs_length_sampling_next() {
253 assert( _curr != NULL, "invariant" );
254 size_t rs_length = _curr->rem_set()->occupied();
255
256 _sampled_rs_lengths += rs_length;
257
258 // The current region may not yet have been added to the
259 // incremental collection set (it gets added when it is
260 // retired as the current allocation region).
261 if (_curr->in_collection_set()) {
262 // Update the collection set policy information for this region
263 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
264 }
265
266 _curr = _curr->get_next_young_region();
267 if (_curr == NULL) {
268 _last_sampled_rs_lengths = _sampled_rs_lengths;
269 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
270 }
271 }
272
273 void
274 YoungList::reset_auxilary_lists() {
275 guarantee( is_empty(), "young list should be empty" );
276 assert(check_list_well_formed(), "young list should be well formed");
277
278 // Add survivor regions to SurvRateGroup.
279 _g1h->g1_policy()->note_start_adding_survivor_regions();
280 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
281
282 int young_index_in_cset = 0;
283 for (HeapRegion* curr = _survivor_head;
284 curr != NULL;
285 curr = curr->get_next_young_region()) {
286 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
287
288 // The region is a non-empty survivor so let's add it to
289 // the incremental collection set for the next evacuation
290 // pause.
291 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
292 young_index_in_cset += 1;
293 }
294 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
295 _g1h->g1_policy()->note_stop_adding_survivor_regions();
296
297 _head = _survivor_head;
298 _length = _survivor_length;
299 if (_survivor_head != NULL) {
300 assert(_survivor_tail != NULL, "cause it shouldn't be");
301 assert(_survivor_length > 0, "invariant");
302 _survivor_tail->set_next_young_region(NULL);
303 }
304
305 // Don't clear the survivor list handles until the start of
306 // the next evacuation pause - we need it in order to re-tag
307 // the survivor regions from this evacuation pause as 'young'
308 // at the start of the next.
309
310 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
311
312 assert(check_list_well_formed(), "young list should be well formed");
313 }
314
315 void YoungList::print() {
316 HeapRegion* lists[] = {_head, _survivor_head};
317 const char* names[] = {"YOUNG", "SURVIVOR"};
318
319 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
320 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
321 HeapRegion *curr = lists[list];
322 if (curr == NULL)
323 gclog_or_tty->print_cr(" empty");
324 while (curr != NULL) {
325 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
326 HR_FORMAT_PARAMS(curr),
327 p2i(curr->prev_top_at_mark_start()),
328 p2i(curr->next_top_at_mark_start()),
329 curr->age_in_surv_rate_group_cond());
330 curr = curr->get_next_young_region();
331 }
332 }
333
334 gclog_or_tty->cr();
335 }
336
337 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
338 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
339 }
340
341 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
342 // The from card cache is not the memory that is actually committed. So we cannot
343 // take advantage of the zero_filled parameter.
344 reset_from_card_cache(start_idx, num_regions);
345 }
346
347 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
348 {
349 // Claim the right to put the region on the dirty cards region list
350 // by installing a self pointer.
351 HeapRegion* next = hr->get_next_dirty_cards_region();
352 if (next == NULL) {
353 HeapRegion* res = (HeapRegion*)
354 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
355 NULL);
356 if (res == NULL) {
357 HeapRegion* head;
358 do {
359 // Put the region to the dirty cards region list.
360 head = _dirty_cards_region_list;
361 next = (HeapRegion*)
362 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
363 if (next == head) {
364 assert(hr->get_next_dirty_cards_region() == hr,
365 "hr->get_next_dirty_cards_region() != hr");
366 if (next == NULL) {
367 // The last region in the list points to itself.
368 hr->set_next_dirty_cards_region(hr);
369 } else {
370 hr->set_next_dirty_cards_region(next);
371 }
372 }
373 } while (next != head);
374 }
375 }
376 }
377
378 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
379 {
380 HeapRegion* head;
381 HeapRegion* hr;
382 do {
383 head = _dirty_cards_region_list;
384 if (head == NULL) {
385 return NULL;
386 }
387 HeapRegion* new_head = head->get_next_dirty_cards_region();
388 if (head == new_head) {
389 // The last region.
390 new_head = NULL;
391 }
392 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
393 head);
394 } while (hr != head);
395 assert(hr != NULL, "invariant");
396 hr->set_next_dirty_cards_region(NULL);
397 return hr;
398 }
399
400 // Returns true if the reference points to an object that
401 // can move in an incremental collection.
402 bool G1CollectedHeap::is_scavengable(const void* p) {
403 HeapRegion* hr = heap_region_containing(p);
404 return !hr->is_pinned();
405 }
406
407 // Private methods.
408
409 HeapRegion*
410 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
411 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
412 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
413 if (!_secondary_free_list.is_empty()) {
414 if (G1ConcRegionFreeingVerbose) {
415 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
416 "secondary_free_list has %u entries",
417 _secondary_free_list.length());
418 }
419 // It looks as if there are free regions available on the
420 // secondary_free_list. Let's move them to the free_list and try
421 // again to allocate from it.
422 append_secondary_free_list();
423
424 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
425 "empty we should have moved at least one entry to the free_list");
426 HeapRegion* res = _hrm.allocate_free_region(is_old);
427 if (G1ConcRegionFreeingVerbose) {
428 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
429 "allocated " HR_FORMAT " from secondary_free_list",
430 HR_FORMAT_PARAMS(res));
431 }
432 return res;
433 }
434
435 // Wait here until we get notified either when (a) there are no
436 // more free regions coming or (b) some regions have been moved on
437 // the secondary_free_list.
438 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
439 }
440
441 if (G1ConcRegionFreeingVerbose) {
442 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
443 "could not allocate from secondary_free_list");
444 }
445 return NULL;
446 }
447
448 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
449 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
450 "the only time we use this to allocate a humongous region is "
451 "when we are allocating a single humongous region");
452
453 HeapRegion* res;
454 if (G1StressConcRegionFreeing) {
455 if (!_secondary_free_list.is_empty()) {
456 if (G1ConcRegionFreeingVerbose) {
457 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
458 "forced to look at the secondary_free_list");
459 }
460 res = new_region_try_secondary_free_list(is_old);
461 if (res != NULL) {
462 return res;
463 }
464 }
465 }
466
467 res = _hrm.allocate_free_region(is_old);
468
469 if (res == NULL) {
470 if (G1ConcRegionFreeingVerbose) {
471 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
472 "res == NULL, trying the secondary_free_list");
473 }
474 res = new_region_try_secondary_free_list(is_old);
475 }
476 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
477 // Currently, only attempts to allocate GC alloc regions set
478 // do_expand to true. So, we should only reach here during a
479 // safepoint. If this assumption changes we might have to
480 // reconsider the use of _expand_heap_after_alloc_failure.
481 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
482
483 ergo_verbose1(ErgoHeapSizing,
484 "attempt heap expansion",
485 ergo_format_reason("region allocation request failed")
486 ergo_format_byte("allocation request"),
487 word_size * HeapWordSize);
488 if (expand(word_size * HeapWordSize)) {
489 // Given that expand() succeeded in expanding the heap, and we
490 // always expand the heap by an amount aligned to the heap
491 // region size, the free list should in theory not be empty.
492 // In either case allocate_free_region() will check for NULL.
493 res = _hrm.allocate_free_region(is_old);
494 } else {
495 _expand_heap_after_alloc_failure = false;
496 }
497 }
498 return res;
499 }
500
501 HeapWord*
502 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
503 uint num_regions,
504 size_t word_size,
505 AllocationContext_t context) {
506 assert(first != G1_NO_HRM_INDEX, "pre-condition");
507 assert(is_humongous(word_size), "word_size should be humongous");
508 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
509
510 // Index of last region in the series + 1.
511 uint last = first + num_regions;
512
513 // We need to initialize the region(s) we just discovered. This is
514 // a bit tricky given that it can happen concurrently with
515 // refinement threads refining cards on these regions and
516 // potentially wanting to refine the BOT as they are scanning
517 // those cards (this can happen shortly after a cleanup; see CR
518 // 6991377). So we have to set up the region(s) carefully and in
519 // a specific order.
520
521 // The word size sum of all the regions we will allocate.
522 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
523 assert(word_size <= word_size_sum, "sanity");
524
525 // This will be the "starts humongous" region.
526 HeapRegion* first_hr = region_at(first);
527 // The header of the new object will be placed at the bottom of
528 // the first region.
529 HeapWord* new_obj = first_hr->bottom();
530 // This will be the new end of the first region in the series that
531 // should also match the end of the last region in the series.
532 HeapWord* new_end = new_obj + word_size_sum;
533 // This will be the new top of the first region that will reflect
534 // this allocation.
535 HeapWord* new_top = new_obj + word_size;
536
537 // First, we need to zero the header of the space that we will be
538 // allocating. When we update top further down, some refinement
539 // threads might try to scan the region. By zeroing the header we
540 // ensure that any thread that will try to scan the region will
541 // come across the zero klass word and bail out.
542 //
543 // NOTE: It would not have been correct to have used
544 // CollectedHeap::fill_with_object() and make the space look like
545 // an int array. The thread that is doing the allocation will
546 // later update the object header to a potentially different array
547 // type and, for a very short period of time, the klass and length
548 // fields will be inconsistent. This could cause a refinement
549 // thread to calculate the object size incorrectly.
550 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
551
552 // We will set up the first region as "starts humongous". This
553 // will also update the BOT covering all the regions to reflect
554 // that there is a single object that starts at the bottom of the
555 // first region.
556 first_hr->set_starts_humongous(new_top, new_end);
557 first_hr->set_allocation_context(context);
558 // Then, if there are any, we will set up the "continues
559 // humongous" regions.
560 HeapRegion* hr = NULL;
561 for (uint i = first + 1; i < last; ++i) {
562 hr = region_at(i);
563 hr->set_continues_humongous(first_hr);
564 hr->set_allocation_context(context);
565 }
566 // If we have "continues humongous" regions (hr != NULL), then the
567 // end of the last one should match new_end.
568 assert(hr == NULL || hr->end() == new_end, "sanity");
569
570 // Up to this point no concurrent thread would have been able to
571 // do any scanning on any region in this series. All the top
572 // fields still point to bottom, so the intersection between
573 // [bottom,top] and [card_start,card_end] will be empty. Before we
574 // update the top fields, we'll do a storestore to make sure that
575 // no thread sees the update to top before the zeroing of the
576 // object header and the BOT initialization.
577 OrderAccess::storestore();
578
579 // Now that the BOT and the object header have been initialized,
580 // we can update top of the "starts humongous" region.
581 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
582 "new_top should be in this region");
583 first_hr->set_top(new_top);
584 if (_hr_printer.is_active()) {
585 HeapWord* bottom = first_hr->bottom();
586 HeapWord* end = first_hr->orig_end();
587 if ((first + 1) == last) {
588 // the series has a single humongous region
589 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
590 } else {
591 // the series has more than one humongous regions
592 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
593 }
594 }
595
596 // Now, we will update the top fields of the "continues humongous"
597 // regions. The reason we need to do this is that, otherwise,
598 // these regions would look empty and this will confuse parts of
599 // G1. For example, the code that looks for a consecutive number
600 // of empty regions will consider them empty and try to
601 // re-allocate them. We can extend is_empty() to also include
602 // !is_continues_humongous(), but it is easier to just update the top
603 // fields here. The way we set top for all regions (i.e., top ==
604 // end for all regions but the last one, top == new_top for the
605 // last one) is actually used when we will free up the humongous
606 // region in free_humongous_region().
607 hr = NULL;
608 for (uint i = first + 1; i < last; ++i) {
609 hr = region_at(i);
610 if ((i + 1) == last) {
611 // last continues humongous region
612 assert(hr->bottom() < new_top && new_top <= hr->end(),
613 "new_top should fall on this region");
614 hr->set_top(new_top);
615 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
616 } else {
617 // not last one
618 assert(new_top > hr->end(), "new_top should be above this region");
619 hr->set_top(hr->end());
620 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
621 }
622 }
623 // If we have continues humongous regions (hr != NULL), then the
624 // end of the last one should match new_end and its top should
625 // match new_top.
626 assert(hr == NULL ||
627 (hr->end() == new_end && hr->top() == new_top), "sanity");
628 check_bitmaps("Humongous Region Allocation", first_hr);
629
630 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
631 increase_used(first_hr->used());
632 _humongous_set.add(first_hr);
633
634 return new_obj;
635 }
636
637 // If could fit into free regions w/o expansion, try.
638 // Otherwise, if can expand, do so.
639 // Otherwise, if using ex regions might help, try with ex given back.
640 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
641 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
642
643 verify_region_sets_optional();
644
645 uint first = G1_NO_HRM_INDEX;
646 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
647
648 if (obj_regions == 1) {
649 // Only one region to allocate, try to use a fast path by directly allocating
650 // from the free lists. Do not try to expand here, we will potentially do that
651 // later.
652 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
653 if (hr != NULL) {
654 first = hr->hrm_index();
655 }
656 } else {
657 // We can't allocate humongous regions spanning more than one region while
658 // cleanupComplete() is running, since some of the regions we find to be
659 // empty might not yet be added to the free list. It is not straightforward
660 // to know in which list they are on so that we can remove them. We only
661 // need to do this if we need to allocate more than one region to satisfy the
662 // current humongous allocation request. If we are only allocating one region
663 // we use the one-region region allocation code (see above), that already
664 // potentially waits for regions from the secondary free list.
665 wait_while_free_regions_coming();
666 append_secondary_free_list_if_not_empty_with_lock();
667
668 // Policy: Try only empty regions (i.e. already committed first). Maybe we
669 // are lucky enough to find some.
670 first = _hrm.find_contiguous_only_empty(obj_regions);
671 if (first != G1_NO_HRM_INDEX) {
672 _hrm.allocate_free_regions_starting_at(first, obj_regions);
673 }
674 }
675
676 if (first == G1_NO_HRM_INDEX) {
677 // Policy: We could not find enough regions for the humongous object in the
678 // free list. Look through the heap to find a mix of free and uncommitted regions.
679 // If so, try expansion.
680 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
681 if (first != G1_NO_HRM_INDEX) {
682 // We found something. Make sure these regions are committed, i.e. expand
683 // the heap. Alternatively we could do a defragmentation GC.
684 ergo_verbose1(ErgoHeapSizing,
685 "attempt heap expansion",
686 ergo_format_reason("humongous allocation request failed")
687 ergo_format_byte("allocation request"),
688 word_size * HeapWordSize);
689
690 _hrm.expand_at(first, obj_regions);
691 g1_policy()->record_new_heap_size(num_regions());
692
693 #ifdef ASSERT
694 for (uint i = first; i < first + obj_regions; ++i) {
695 HeapRegion* hr = region_at(i);
696 assert(hr->is_free(), "sanity");
697 assert(hr->is_empty(), "sanity");
698 assert(is_on_master_free_list(hr), "sanity");
699 }
700 #endif
701 _hrm.allocate_free_regions_starting_at(first, obj_regions);
702 } else {
703 // Policy: Potentially trigger a defragmentation GC.
704 }
705 }
706
707 HeapWord* result = NULL;
708 if (first != G1_NO_HRM_INDEX) {
709 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
710 word_size, context);
711 assert(result != NULL, "it should always return a valid result");
712
713 // A successful humongous object allocation changes the used space
714 // information of the old generation so we need to recalculate the
715 // sizes and update the jstat counters here.
716 g1mm()->update_sizes();
717 }
718
719 verify_region_sets_optional();
720
721 return result;
722 }
723
724 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
725 assert_heap_not_locked_and_not_at_safepoint();
726 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
727
728 uint dummy_gc_count_before;
729 uint dummy_gclocker_retry_count = 0;
730 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
731 }
732
733 HeapWord*
734 G1CollectedHeap::mem_allocate(size_t word_size,
735 bool* gc_overhead_limit_was_exceeded) {
736 assert_heap_not_locked_and_not_at_safepoint();
737
738 // Loop until the allocation is satisfied, or unsatisfied after GC.
739 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
740 uint gc_count_before;
741
742 HeapWord* result = NULL;
743 if (!is_humongous(word_size)) {
744 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
745 } else {
746 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
747 }
748 if (result != NULL) {
749 return result;
750 }
751
752 // Create the garbage collection operation...
753 VM_G1CollectForAllocation op(gc_count_before, word_size);
754 op.set_allocation_context(AllocationContext::current());
755
756 // ...and get the VM thread to execute it.
757 VMThread::execute(&op);
758
759 if (op.prologue_succeeded() && op.pause_succeeded()) {
760 // If the operation was successful we'll return the result even
761 // if it is NULL. If the allocation attempt failed immediately
762 // after a Full GC, it's unlikely we'll be able to allocate now.
763 HeapWord* result = op.result();
764 if (result != NULL && !is_humongous(word_size)) {
765 // Allocations that take place on VM operations do not do any
766 // card dirtying and we have to do it here. We only have to do
767 // this for non-humongous allocations, though.
768 dirty_young_block(result, word_size);
769 }
770 return result;
771 } else {
772 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
773 return NULL;
774 }
775 assert(op.result() == NULL,
776 "the result should be NULL if the VM op did not succeed");
777 }
778
779 // Give a warning if we seem to be looping forever.
780 if ((QueuedAllocationWarningCount > 0) &&
781 (try_count % QueuedAllocationWarningCount == 0)) {
782 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
783 }
784 }
785
786 ShouldNotReachHere();
787 return NULL;
788 }
789
790 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
791 AllocationContext_t context,
792 uint* gc_count_before_ret,
793 uint* gclocker_retry_count_ret) {
794 // Make sure you read the note in attempt_allocation_humongous().
795
796 assert_heap_not_locked_and_not_at_safepoint();
797 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
798 "be called for humongous allocation requests");
799
800 // We should only get here after the first-level allocation attempt
801 // (attempt_allocation()) failed to allocate.
802
803 // We will loop until a) we manage to successfully perform the
804 // allocation or b) we successfully schedule a collection which
805 // fails to perform the allocation. b) is the only case when we'll
806 // return NULL.
807 HeapWord* result = NULL;
808 for (int try_count = 1; /* we'll return */; try_count += 1) {
809 bool should_try_gc;
810 uint gc_count_before;
811
812 {
813 MutexLockerEx x(Heap_lock);
814 result = _allocator->attempt_allocation_locked(word_size, context);
815 if (result != NULL) {
816 return result;
817 }
818
819 if (GC_locker::is_active_and_needs_gc()) {
820 if (g1_policy()->can_expand_young_list()) {
821 // No need for an ergo verbose message here,
822 // can_expand_young_list() does this when it returns true.
823 result = _allocator->attempt_allocation_force(word_size, context);
824 if (result != NULL) {
825 return result;
826 }
827 }
828 should_try_gc = false;
829 } else {
830 // The GCLocker may not be active but the GCLocker initiated
831 // GC may not yet have been performed (GCLocker::needs_gc()
832 // returns true). In this case we do not try this GC and
833 // wait until the GCLocker initiated GC is performed, and
834 // then retry the allocation.
835 if (GC_locker::needs_gc()) {
836 should_try_gc = false;
837 } else {
838 // Read the GC count while still holding the Heap_lock.
839 gc_count_before = total_collections();
840 should_try_gc = true;
841 }
842 }
843 }
844
845 if (should_try_gc) {
846 bool succeeded;
847 result = do_collection_pause(word_size, gc_count_before, &succeeded,
848 GCCause::_g1_inc_collection_pause);
849 if (result != NULL) {
850 assert(succeeded, "only way to get back a non-NULL result");
851 return result;
852 }
853
854 if (succeeded) {
855 // If we get here we successfully scheduled a collection which
856 // failed to allocate. No point in trying to allocate
857 // further. We'll just return NULL.
858 MutexLockerEx x(Heap_lock);
859 *gc_count_before_ret = total_collections();
860 return NULL;
861 }
862 } else {
863 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
864 MutexLockerEx x(Heap_lock);
865 *gc_count_before_ret = total_collections();
866 return NULL;
867 }
868 // The GCLocker is either active or the GCLocker initiated
869 // GC has not yet been performed. Stall until it is and
870 // then retry the allocation.
871 GC_locker::stall_until_clear();
872 (*gclocker_retry_count_ret) += 1;
873 }
874
875 // We can reach here if we were unsuccessful in scheduling a
876 // collection (because another thread beat us to it) or if we were
877 // stalled due to the GC locker. In either can we should retry the
878 // allocation attempt in case another thread successfully
879 // performed a collection and reclaimed enough space. We do the
880 // first attempt (without holding the Heap_lock) here and the
881 // follow-on attempt will be at the start of the next loop
882 // iteration (after taking the Heap_lock).
883 result = _allocator->attempt_allocation(word_size, context);
884 if (result != NULL) {
885 return result;
886 }
887
888 // Give a warning if we seem to be looping forever.
889 if ((QueuedAllocationWarningCount > 0) &&
890 (try_count % QueuedAllocationWarningCount == 0)) {
891 warning("G1CollectedHeap::attempt_allocation_slow() "
892 "retries %d times", try_count);
893 }
894 }
895
896 ShouldNotReachHere();
897 return NULL;
898 }
899
900 void G1CollectedHeap::begin_archive_alloc_range() {
901 assert_at_safepoint(true /* should_be_vm_thread */);
902 if (_archive_allocator == NULL) {
903 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
904 }
905 }
906
907 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
908 // Allocations in archive regions cannot be of a size that would be considered
909 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
910 // may be different at archive-restore time.
911 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
912 }
913
914 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
915 assert_at_safepoint(true /* should_be_vm_thread */);
916 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
917 if (is_archive_alloc_too_large(word_size)) {
918 return NULL;
919 }
920 return _archive_allocator->archive_mem_allocate(word_size);
921 }
922
923 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
924 size_t end_alignment_in_bytes) {
925 assert_at_safepoint(true /* should_be_vm_thread */);
926 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
927
928 // Call complete_archive to do the real work, filling in the MemRegion
929 // array with the archive regions.
930 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
931 delete _archive_allocator;
932 _archive_allocator = NULL;
933 }
934
935 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
936 assert(ranges != NULL, "MemRegion array NULL");
937 assert(count != 0, "No MemRegions provided");
938 MemRegion reserved = _hrm.reserved();
939 for (size_t i = 0; i < count; i++) {
940 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
941 return false;
942 }
943 }
944 return true;
945 }
946
947 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
948 assert(!is_init_completed(), "Expect to be called at JVM init time");
949 assert(ranges != NULL, "MemRegion array NULL");
950 assert(count != 0, "No MemRegions provided");
951 MutexLockerEx x(Heap_lock);
952
953 MemRegion reserved = _hrm.reserved();
954 HeapWord* prev_last_addr = NULL;
955 HeapRegion* prev_last_region = NULL;
956
957 // Temporarily disable pretouching of heap pages. This interface is used
958 // when mmap'ing archived heap data in, so pre-touching is wasted.
959 FlagSetting fs(AlwaysPreTouch, false);
960
961 // Enable archive object checking in G1MarkSweep. We have to let it know
962 // about each archive range, so that objects in those ranges aren't marked.
963 G1MarkSweep::enable_archive_object_check();
964
965 // For each specified MemRegion range, allocate the corresponding G1
966 // regions and mark them as archive regions. We expect the ranges in
967 // ascending starting address order, without overlap.
968 for (size_t i = 0; i < count; i++) {
969 MemRegion curr_range = ranges[i];
970 HeapWord* start_address = curr_range.start();
971 size_t word_size = curr_range.word_size();
972 HeapWord* last_address = curr_range.last();
973 size_t commits = 0;
974
975 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
976 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
977 p2i(start_address), p2i(last_address));
978 guarantee(start_address > prev_last_addr,
979 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
980 p2i(start_address), p2i(prev_last_addr));
981 prev_last_addr = last_address;
982
983 // Check for ranges that start in the same G1 region in which the previous
984 // range ended, and adjust the start address so we don't try to allocate
985 // the same region again. If the current range is entirely within that
986 // region, skip it, just adjusting the recorded top.
987 HeapRegion* start_region = _hrm.addr_to_region(start_address);
988 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
989 start_address = start_region->end();
990 if (start_address > last_address) {
991 increase_used(word_size * HeapWordSize);
992 start_region->set_top(last_address + 1);
993 continue;
994 }
995 start_region->set_top(start_address);
996 curr_range = MemRegion(start_address, last_address + 1);
997 start_region = _hrm.addr_to_region(start_address);
998 }
999
1000 // Perform the actual region allocation, exiting if it fails.
1001 // Then note how much new space we have allocated.
1002 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1003 return false;
1004 }
1005 increase_used(word_size * HeapWordSize);
1006 if (commits != 0) {
1007 ergo_verbose1(ErgoHeapSizing,
1008 "attempt heap expansion",
1009 ergo_format_reason("allocate archive regions")
1010 ergo_format_byte("total size"),
1011 HeapRegion::GrainWords * HeapWordSize * commits);
1012 }
1013
1014 // Mark each G1 region touched by the range as archive, add it to the old set,
1015 // and set the allocation context and top.
1016 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1017 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1018 prev_last_region = last_region;
1019
1020 while (curr_region != NULL) {
1021 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1022 "Region already in use (index %u)", curr_region->hrm_index());
1023 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1024 curr_region->set_allocation_context(AllocationContext::system());
1025 curr_region->set_archive();
1026 _old_set.add(curr_region);
1027 if (curr_region != last_region) {
1028 curr_region->set_top(curr_region->end());
1029 curr_region = _hrm.next_region_in_heap(curr_region);
1030 } else {
1031 curr_region->set_top(last_address + 1);
1032 curr_region = NULL;
1033 }
1034 }
1035
1036 // Notify mark-sweep of the archive range.
1037 G1MarkSweep::set_range_archive(curr_range, true);
1038 }
1039 return true;
1040 }
1041
1042 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1043 assert(!is_init_completed(), "Expect to be called at JVM init time");
1044 assert(ranges != NULL, "MemRegion array NULL");
1045 assert(count != 0, "No MemRegions provided");
1046 MemRegion reserved = _hrm.reserved();
1047 HeapWord *prev_last_addr = NULL;
1048 HeapRegion* prev_last_region = NULL;
1049
1050 // For each MemRegion, create filler objects, if needed, in the G1 regions
1051 // that contain the address range. The address range actually within the
1052 // MemRegion will not be modified. That is assumed to have been initialized
1053 // elsewhere, probably via an mmap of archived heap data.
1054 MutexLockerEx x(Heap_lock);
1055 for (size_t i = 0; i < count; i++) {
1056 HeapWord* start_address = ranges[i].start();
1057 HeapWord* last_address = ranges[i].last();
1058
1059 assert(reserved.contains(start_address) && reserved.contains(last_address),
1060 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1061 p2i(start_address), p2i(last_address));
1062 assert(start_address > prev_last_addr,
1063 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1064 p2i(start_address), p2i(prev_last_addr));
1065
1066 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1067 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1068 HeapWord* bottom_address = start_region->bottom();
1069
1070 // Check for a range beginning in the same region in which the
1071 // previous one ended.
1072 if (start_region == prev_last_region) {
1073 bottom_address = prev_last_addr + 1;
1074 }
1075
1076 // Verify that the regions were all marked as archive regions by
1077 // alloc_archive_regions.
1078 HeapRegion* curr_region = start_region;
1079 while (curr_region != NULL) {
1080 guarantee(curr_region->is_archive(),
1081 "Expected archive region at index %u", curr_region->hrm_index());
1082 if (curr_region != last_region) {
1083 curr_region = _hrm.next_region_in_heap(curr_region);
1084 } else {
1085 curr_region = NULL;
1086 }
1087 }
1088
1089 prev_last_addr = last_address;
1090 prev_last_region = last_region;
1091
1092 // Fill the memory below the allocated range with dummy object(s),
1093 // if the region bottom does not match the range start, or if the previous
1094 // range ended within the same G1 region, and there is a gap.
1095 if (start_address != bottom_address) {
1096 size_t fill_size = pointer_delta(start_address, bottom_address);
1097 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1098 increase_used(fill_size * HeapWordSize);
1099 }
1100 }
1101 }
1102
1103 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1104 uint* gc_count_before_ret,
1105 uint* gclocker_retry_count_ret) {
1106 assert_heap_not_locked_and_not_at_safepoint();
1107 assert(!is_humongous(word_size), "attempt_allocation() should not "
1108 "be called for humongous allocation requests");
1109
1110 AllocationContext_t context = AllocationContext::current();
1111 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1112
1113 if (result == NULL) {
1114 result = attempt_allocation_slow(word_size,
1115 context,
1116 gc_count_before_ret,
1117 gclocker_retry_count_ret);
1118 }
1119 assert_heap_not_locked();
1120 if (result != NULL) {
1121 dirty_young_block(result, word_size);
1122 }
1123 return result;
1124 }
1125
1126 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1127 assert(!is_init_completed(), "Expect to be called at JVM init time");
1128 assert(ranges != NULL, "MemRegion array NULL");
1129 assert(count != 0, "No MemRegions provided");
1130 MemRegion reserved = _hrm.reserved();
1131 HeapWord* prev_last_addr = NULL;
1132 HeapRegion* prev_last_region = NULL;
1133 size_t size_used = 0;
1134 size_t uncommitted_regions = 0;
1135
1136 // For each Memregion, free the G1 regions that constitute it, and
1137 // notify mark-sweep that the range is no longer to be considered 'archive.'
1138 MutexLockerEx x(Heap_lock);
1139 for (size_t i = 0; i < count; i++) {
1140 HeapWord* start_address = ranges[i].start();
1141 HeapWord* last_address = ranges[i].last();
1142
1143 assert(reserved.contains(start_address) && reserved.contains(last_address),
1144 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1145 p2i(start_address), p2i(last_address));
1146 assert(start_address > prev_last_addr,
1147 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1148 p2i(start_address), p2i(prev_last_addr));
1149 size_used += ranges[i].byte_size();
1150 prev_last_addr = last_address;
1151
1152 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1153 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1154
1155 // Check for ranges that start in the same G1 region in which the previous
1156 // range ended, and adjust the start address so we don't try to free
1157 // the same region again. If the current range is entirely within that
1158 // region, skip it.
1159 if (start_region == prev_last_region) {
1160 start_address = start_region->end();
1161 if (start_address > last_address) {
1162 continue;
1163 }
1164 start_region = _hrm.addr_to_region(start_address);
1165 }
1166 prev_last_region = last_region;
1167
1168 // After verifying that each region was marked as an archive region by
1169 // alloc_archive_regions, set it free and empty and uncommit it.
1170 HeapRegion* curr_region = start_region;
1171 while (curr_region != NULL) {
1172 guarantee(curr_region->is_archive(),
1173 "Expected archive region at index %u", curr_region->hrm_index());
1174 uint curr_index = curr_region->hrm_index();
1175 _old_set.remove(curr_region);
1176 curr_region->set_free();
1177 curr_region->set_top(curr_region->bottom());
1178 if (curr_region != last_region) {
1179 curr_region = _hrm.next_region_in_heap(curr_region);
1180 } else {
1181 curr_region = NULL;
1182 }
1183 _hrm.shrink_at(curr_index, 1);
1184 uncommitted_regions++;
1185 }
1186
1187 // Notify mark-sweep that this is no longer an archive range.
1188 G1MarkSweep::set_range_archive(ranges[i], false);
1189 }
1190
1191 if (uncommitted_regions != 0) {
1192 ergo_verbose1(ErgoHeapSizing,
1193 "attempt heap shrinking",
1194 ergo_format_reason("uncommitted archive regions")
1195 ergo_format_byte("total size"),
1196 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1197 }
1198 decrease_used(size_used);
1199 }
1200
1201 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1202 uint* gc_count_before_ret,
1203 uint* gclocker_retry_count_ret) {
1204 // The structure of this method has a lot of similarities to
1205 // attempt_allocation_slow(). The reason these two were not merged
1206 // into a single one is that such a method would require several "if
1207 // allocation is not humongous do this, otherwise do that"
1208 // conditional paths which would obscure its flow. In fact, an early
1209 // version of this code did use a unified method which was harder to
1210 // follow and, as a result, it had subtle bugs that were hard to
1211 // track down. So keeping these two methods separate allows each to
1212 // be more readable. It will be good to keep these two in sync as
1213 // much as possible.
1214
1215 assert_heap_not_locked_and_not_at_safepoint();
1216 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1217 "should only be called for humongous allocations");
1218
1219 // Humongous objects can exhaust the heap quickly, so we should check if we
1220 // need to start a marking cycle at each humongous object allocation. We do
1221 // the check before we do the actual allocation. The reason for doing it
1222 // before the allocation is that we avoid having to keep track of the newly
1223 // allocated memory while we do a GC.
1224 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1225 word_size)) {
1226 collect(GCCause::_g1_humongous_allocation);
1227 }
1228
1229 // We will loop until a) we manage to successfully perform the
1230 // allocation or b) we successfully schedule a collection which
1231 // fails to perform the allocation. b) is the only case when we'll
1232 // return NULL.
1233 HeapWord* result = NULL;
1234 for (int try_count = 1; /* we'll return */; try_count += 1) {
1235 bool should_try_gc;
1236 uint gc_count_before;
1237
1238 {
1239 MutexLockerEx x(Heap_lock);
1240
1241 // Given that humongous objects are not allocated in young
1242 // regions, we'll first try to do the allocation without doing a
1243 // collection hoping that there's enough space in the heap.
1244 result = humongous_obj_allocate(word_size, AllocationContext::current());
1245 if (result != NULL) {
1246 return result;
1247 }
1248
1249 if (GC_locker::is_active_and_needs_gc()) {
1250 should_try_gc = false;
1251 } else {
1252 // The GCLocker may not be active but the GCLocker initiated
1253 // GC may not yet have been performed (GCLocker::needs_gc()
1254 // returns true). In this case we do not try this GC and
1255 // wait until the GCLocker initiated GC is performed, and
1256 // then retry the allocation.
1257 if (GC_locker::needs_gc()) {
1258 should_try_gc = false;
1259 } else {
1260 // Read the GC count while still holding the Heap_lock.
1261 gc_count_before = total_collections();
1262 should_try_gc = true;
1263 }
1264 }
1265 }
1266
1267 if (should_try_gc) {
1268 // If we failed to allocate the humongous object, we should try to
1269 // do a collection pause (if we're allowed) in case it reclaims
1270 // enough space for the allocation to succeed after the pause.
1271
1272 bool succeeded;
1273 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1274 GCCause::_g1_humongous_allocation);
1275 if (result != NULL) {
1276 assert(succeeded, "only way to get back a non-NULL result");
1277 return result;
1278 }
1279
1280 if (succeeded) {
1281 // If we get here we successfully scheduled a collection which
1282 // failed to allocate. No point in trying to allocate
1283 // further. We'll just return NULL.
1284 MutexLockerEx x(Heap_lock);
1285 *gc_count_before_ret = total_collections();
1286 return NULL;
1287 }
1288 } else {
1289 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1290 MutexLockerEx x(Heap_lock);
1291 *gc_count_before_ret = total_collections();
1292 return NULL;
1293 }
1294 // The GCLocker is either active or the GCLocker initiated
1295 // GC has not yet been performed. Stall until it is and
1296 // then retry the allocation.
1297 GC_locker::stall_until_clear();
1298 (*gclocker_retry_count_ret) += 1;
1299 }
1300
1301 // We can reach here if we were unsuccessful in scheduling a
1302 // collection (because another thread beat us to it) or if we were
1303 // stalled due to the GC locker. In either can we should retry the
1304 // allocation attempt in case another thread successfully
1305 // performed a collection and reclaimed enough space. Give a
1306 // warning if we seem to be looping forever.
1307
1308 if ((QueuedAllocationWarningCount > 0) &&
1309 (try_count % QueuedAllocationWarningCount == 0)) {
1310 warning("G1CollectedHeap::attempt_allocation_humongous() "
1311 "retries %d times", try_count);
1312 }
1313 }
1314
1315 ShouldNotReachHere();
1316 return NULL;
1317 }
1318
1319 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1320 AllocationContext_t context,
1321 bool expect_null_mutator_alloc_region) {
1322 assert_at_safepoint(true /* should_be_vm_thread */);
1323 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1324 "the current alloc region was unexpectedly found to be non-NULL");
1325
1326 if (!is_humongous(word_size)) {
1327 return _allocator->attempt_allocation_locked(word_size, context);
1328 } else {
1329 HeapWord* result = humongous_obj_allocate(word_size, context);
1330 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1331 collector_state()->set_initiate_conc_mark_if_possible(true);
1332 }
1333 return result;
1334 }
1335
1336 ShouldNotReachHere();
1337 }
1338
1339 class PostMCRemSetClearClosure: public HeapRegionClosure {
1340 G1CollectedHeap* _g1h;
1341 ModRefBarrierSet* _mr_bs;
1342 public:
1343 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1344 _g1h(g1h), _mr_bs(mr_bs) {}
1345
1346 bool doHeapRegion(HeapRegion* r) {
1347 HeapRegionRemSet* hrrs = r->rem_set();
1348
1349 if (r->is_continues_humongous()) {
1350 // We'll assert that the strong code root list and RSet is empty
1351 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1352 assert(hrrs->occupied() == 0, "RSet should be empty");
1353 return false;
1354 }
1355
1356 _g1h->reset_gc_time_stamps(r);
1357 hrrs->clear();
1358 // You might think here that we could clear just the cards
1359 // corresponding to the used region. But no: if we leave a dirty card
1360 // in a region we might allocate into, then it would prevent that card
1361 // from being enqueued, and cause it to be missed.
1362 // Re: the performance cost: we shouldn't be doing full GC anyway!
1363 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1364
1365 return false;
1366 }
1367 };
1368
1369 void G1CollectedHeap::clear_rsets_post_compaction() {
1370 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1371 heap_region_iterate(&rs_clear);
1372 }
1373
1374 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1375 G1CollectedHeap* _g1h;
1376 UpdateRSOopClosure _cl;
1377 public:
1378 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1379 _cl(g1->g1_rem_set(), worker_i),
1380 _g1h(g1)
1381 { }
1382
1383 bool doHeapRegion(HeapRegion* r) {
1384 if (!r->is_continues_humongous()) {
1385 _cl.set_from(r);
1386 r->oop_iterate(&_cl);
1387 }
1388 return false;
1389 }
1390 };
1391
1392 class ParRebuildRSTask: public AbstractGangTask {
1393 G1CollectedHeap* _g1;
1394 HeapRegionClaimer _hrclaimer;
1395
1396 public:
1397 ParRebuildRSTask(G1CollectedHeap* g1) :
1398 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1399
1400 void work(uint worker_id) {
1401 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1402 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1403 }
1404 };
1405
1406 class PostCompactionPrinterClosure: public HeapRegionClosure {
1407 private:
1408 G1HRPrinter* _hr_printer;
1409 public:
1410 bool doHeapRegion(HeapRegion* hr) {
1411 assert(!hr->is_young(), "not expecting to find young regions");
1412 if (hr->is_free()) {
1413 // We only generate output for non-empty regions.
1414 } else if (hr->is_starts_humongous()) {
1415 if (hr->region_num() == 1) {
1416 // single humongous region
1417 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1418 } else {
1419 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1420 }
1421 } else if (hr->is_continues_humongous()) {
1422 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1423 } else if (hr->is_archive()) {
1424 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1425 } else if (hr->is_old()) {
1426 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1427 } else {
1428 ShouldNotReachHere();
1429 }
1430 return false;
1431 }
1432
1433 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1434 : _hr_printer(hr_printer) { }
1435 };
1436
1437 void G1CollectedHeap::print_hrm_post_compaction() {
1438 PostCompactionPrinterClosure cl(hr_printer());
1439 heap_region_iterate(&cl);
1440 }
1441
1442 bool G1CollectedHeap::do_collection(bool explicit_gc,
1443 bool clear_all_soft_refs,
1444 size_t word_size) {
1445 assert_at_safepoint(true /* should_be_vm_thread */);
1446
1447 if (GC_locker::check_active_before_gc()) {
1448 return false;
1449 }
1450
1451 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1452 gc_timer->register_gc_start();
1453
1454 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1455 GCIdMark gc_id_mark;
1456 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1457
1458 SvcGCMarker sgcm(SvcGCMarker::FULL);
1459 ResourceMark rm;
1460
1461 G1Log::update_level();
1462 print_heap_before_gc();
1463 trace_heap_before_gc(gc_tracer);
1464
1465 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1466
1467 verify_region_sets_optional();
1468
1469 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1470 collector_policy()->should_clear_all_soft_refs();
1471
1472 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1473
1474 {
1475 IsGCActiveMark x;
1476
1477 // Timing
1478 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1479 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1480
1481 {
1482 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1483 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1484 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1485
1486 g1_policy()->record_full_collection_start();
1487
1488 // Note: When we have a more flexible GC logging framework that
1489 // allows us to add optional attributes to a GC log record we
1490 // could consider timing and reporting how long we wait in the
1491 // following two methods.
1492 wait_while_free_regions_coming();
1493 // If we start the compaction before the CM threads finish
1494 // scanning the root regions we might trip them over as we'll
1495 // be moving objects / updating references. So let's wait until
1496 // they are done. By telling them to abort, they should complete
1497 // early.
1498 _cm->root_regions()->abort();
1499 _cm->root_regions()->wait_until_scan_finished();
1500 append_secondary_free_list_if_not_empty_with_lock();
1501
1502 gc_prologue(true);
1503 increment_total_collections(true /* full gc */);
1504 increment_old_marking_cycles_started();
1505
1506 assert(used() == recalculate_used(), "Should be equal");
1507
1508 verify_before_gc();
1509
1510 check_bitmaps("Full GC Start");
1511 pre_full_gc_dump(gc_timer);
1512
1513 COMPILER2_PRESENT(DerivedPointerTable::clear());
1514
1515 // Disable discovery and empty the discovered lists
1516 // for the CM ref processor.
1517 ref_processor_cm()->disable_discovery();
1518 ref_processor_cm()->abandon_partial_discovery();
1519 ref_processor_cm()->verify_no_references_recorded();
1520
1521 // Abandon current iterations of concurrent marking and concurrent
1522 // refinement, if any are in progress. We have to do this before
1523 // wait_until_scan_finished() below.
1524 concurrent_mark()->abort();
1525
1526 // Make sure we'll choose a new allocation region afterwards.
1527 _allocator->release_mutator_alloc_region();
1528 _allocator->abandon_gc_alloc_regions();
1529 g1_rem_set()->cleanupHRRS();
1530
1531 // We should call this after we retire any currently active alloc
1532 // regions so that all the ALLOC / RETIRE events are generated
1533 // before the start GC event.
1534 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1535
1536 // We may have added regions to the current incremental collection
1537 // set between the last GC or pause and now. We need to clear the
1538 // incremental collection set and then start rebuilding it afresh
1539 // after this full GC.
1540 abandon_collection_set(g1_policy()->inc_cset_head());
1541 g1_policy()->clear_incremental_cset();
1542 g1_policy()->stop_incremental_cset_building();
1543
1544 tear_down_region_sets(false /* free_list_only */);
1545 collector_state()->set_gcs_are_young(true);
1546
1547 // See the comments in g1CollectedHeap.hpp and
1548 // G1CollectedHeap::ref_processing_init() about
1549 // how reference processing currently works in G1.
1550
1551 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1552 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1553
1554 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1555 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1556
1557 ref_processor_stw()->enable_discovery();
1558 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1559
1560 // Do collection work
1561 {
1562 HandleMark hm; // Discard invalid handles created during gc
1563 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1564 }
1565
1566 assert(num_free_regions() == 0, "we should not have added any free regions");
1567 rebuild_region_sets(false /* free_list_only */);
1568
1569 // Enqueue any discovered reference objects that have
1570 // not been removed from the discovered lists.
1571 ref_processor_stw()->enqueue_discovered_references();
1572
1573 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1574
1575 MemoryService::track_memory_usage();
1576
1577 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1578 ref_processor_stw()->verify_no_references_recorded();
1579
1580 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1581 ClassLoaderDataGraph::purge();
1582 MetaspaceAux::verify_metrics();
1583
1584 // Note: since we've just done a full GC, concurrent
1585 // marking is no longer active. Therefore we need not
1586 // re-enable reference discovery for the CM ref processor.
1587 // That will be done at the start of the next marking cycle.
1588 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1589 ref_processor_cm()->verify_no_references_recorded();
1590
1591 reset_gc_time_stamp();
1592 // Since everything potentially moved, we will clear all remembered
1593 // sets, and clear all cards. Later we will rebuild remembered
1594 // sets. We will also reset the GC time stamps of the regions.
1595 clear_rsets_post_compaction();
1596 check_gc_time_stamps();
1597
1598 // Resize the heap if necessary.
1599 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1600
1601 if (_hr_printer.is_active()) {
1602 // We should do this after we potentially resize the heap so
1603 // that all the COMMIT / UNCOMMIT events are generated before
1604 // the end GC event.
1605
1606 print_hrm_post_compaction();
1607 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1608 }
1609
1610 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1611 if (hot_card_cache->use_cache()) {
1612 hot_card_cache->reset_card_counts();
1613 hot_card_cache->reset_hot_cache();
1614 }
1615
1616 // Rebuild remembered sets of all regions.
1617 uint n_workers =
1618 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1619 workers()->active_workers(),
1620 Threads::number_of_non_daemon_threads());
1621 workers()->set_active_workers(n_workers);
1622
1623 ParRebuildRSTask rebuild_rs_task(this);
1624 workers()->run_task(&rebuild_rs_task);
1625
1626 // Rebuild the strong code root lists for each region
1627 rebuild_strong_code_roots();
1628
1629 if (true) { // FIXME
1630 MetaspaceGC::compute_new_size();
1631 }
1632
1633 #ifdef TRACESPINNING
1634 ParallelTaskTerminator::print_termination_counts();
1635 #endif
1636
1637 // Discard all rset updates
1638 JavaThread::dirty_card_queue_set().abandon_logs();
1639 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1640
1641 _young_list->reset_sampled_info();
1642 // At this point there should be no regions in the
1643 // entire heap tagged as young.
1644 assert(check_young_list_empty(true /* check_heap */),
1645 "young list should be empty at this point");
1646
1647 // Update the number of full collections that have been completed.
1648 increment_old_marking_cycles_completed(false /* concurrent */);
1649
1650 _hrm.verify_optional();
1651 verify_region_sets_optional();
1652
1653 verify_after_gc();
1654
1655 // Clear the previous marking bitmap, if needed for bitmap verification.
1656 // Note we cannot do this when we clear the next marking bitmap in
1657 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1658 // objects marked during a full GC against the previous bitmap.
1659 // But we need to clear it before calling check_bitmaps below since
1660 // the full GC has compacted objects and updated TAMS but not updated
1661 // the prev bitmap.
1662 if (G1VerifyBitmaps) {
1663 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1664 }
1665 check_bitmaps("Full GC End");
1666
1667 // Start a new incremental collection set for the next pause
1668 assert(g1_policy()->collection_set() == NULL, "must be");
1669 g1_policy()->start_incremental_cset_building();
1670
1671 clear_cset_fast_test();
1672
1673 _allocator->init_mutator_alloc_region();
1674
1675 g1_policy()->record_full_collection_end();
1676
1677 if (G1Log::fine()) {
1678 g1_policy()->print_heap_transition();
1679 }
1680
1681 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1682 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1683 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1684 // before any GC notifications are raised.
1685 g1mm()->update_sizes();
1686
1687 gc_epilogue(true);
1688 }
1689
1690 if (G1Log::finer()) {
1691 g1_policy()->print_detailed_heap_transition(true /* full */);
1692 }
1693
1694 print_heap_after_gc();
1695 trace_heap_after_gc(gc_tracer);
1696
1697 post_full_gc_dump(gc_timer);
1698
1699 gc_timer->register_gc_end();
1700 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1701 }
1702
1703 return true;
1704 }
1705
1706 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1707 // do_collection() will return whether it succeeded in performing
1708 // the GC. Currently, there is no facility on the
1709 // do_full_collection() API to notify the caller than the collection
1710 // did not succeed (e.g., because it was locked out by the GC
1711 // locker). So, right now, we'll ignore the return value.
1712 bool dummy = do_collection(true, /* explicit_gc */
1713 clear_all_soft_refs,
1714 0 /* word_size */);
1715 }
1716
1717 // This code is mostly copied from TenuredGeneration.
1718 void
1719 G1CollectedHeap::
1720 resize_if_necessary_after_full_collection(size_t word_size) {
1721 // Include the current allocation, if any, and bytes that will be
1722 // pre-allocated to support collections, as "used".
1723 const size_t used_after_gc = used();
1724 const size_t capacity_after_gc = capacity();
1725 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1726
1727 // This is enforced in arguments.cpp.
1728 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1729 "otherwise the code below doesn't make sense");
1730
1731 // We don't have floating point command-line arguments
1732 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1733 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1734 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1735 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1736
1737 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1738 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1739
1740 // We have to be careful here as these two calculations can overflow
1741 // 32-bit size_t's.
1742 double used_after_gc_d = (double) used_after_gc;
1743 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1744 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1745
1746 // Let's make sure that they are both under the max heap size, which
1747 // by default will make them fit into a size_t.
1748 double desired_capacity_upper_bound = (double) max_heap_size;
1749 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1750 desired_capacity_upper_bound);
1751 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1752 desired_capacity_upper_bound);
1753
1754 // We can now safely turn them into size_t's.
1755 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1756 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1757
1758 // This assert only makes sense here, before we adjust them
1759 // with respect to the min and max heap size.
1760 assert(minimum_desired_capacity <= maximum_desired_capacity,
1761 "minimum_desired_capacity = " SIZE_FORMAT ", "
1762 "maximum_desired_capacity = " SIZE_FORMAT,
1763 minimum_desired_capacity, maximum_desired_capacity);
1764
1765 // Should not be greater than the heap max size. No need to adjust
1766 // it with respect to the heap min size as it's a lower bound (i.e.,
1767 // we'll try to make the capacity larger than it, not smaller).
1768 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1769 // Should not be less than the heap min size. No need to adjust it
1770 // with respect to the heap max size as it's an upper bound (i.e.,
1771 // we'll try to make the capacity smaller than it, not greater).
1772 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1773
1774 if (capacity_after_gc < minimum_desired_capacity) {
1775 // Don't expand unless it's significant
1776 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1777 ergo_verbose4(ErgoHeapSizing,
1778 "attempt heap expansion",
1779 ergo_format_reason("capacity lower than "
1780 "min desired capacity after Full GC")
1781 ergo_format_byte("capacity")
1782 ergo_format_byte("occupancy")
1783 ergo_format_byte_perc("min desired capacity"),
1784 capacity_after_gc, used_after_gc,
1785 minimum_desired_capacity, (double) MinHeapFreeRatio);
1786 expand(expand_bytes);
1787
1788 // No expansion, now see if we want to shrink
1789 } else if (capacity_after_gc > maximum_desired_capacity) {
1790 // Capacity too large, compute shrinking size
1791 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1792 ergo_verbose4(ErgoHeapSizing,
1793 "attempt heap shrinking",
1794 ergo_format_reason("capacity higher than "
1795 "max desired capacity after Full GC")
1796 ergo_format_byte("capacity")
1797 ergo_format_byte("occupancy")
1798 ergo_format_byte_perc("max desired capacity"),
1799 capacity_after_gc, used_after_gc,
1800 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1801 shrink(shrink_bytes);
1802 }
1803 }
1804
1805 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1806 AllocationContext_t context,
1807 bool do_gc,
1808 bool clear_all_soft_refs,
1809 bool expect_null_mutator_alloc_region,
1810 bool* gc_succeeded) {
1811 *gc_succeeded = true;
1812 // Let's attempt the allocation first.
1813 HeapWord* result =
1814 attempt_allocation_at_safepoint(word_size,
1815 context,
1816 expect_null_mutator_alloc_region);
1817 if (result != NULL) {
1818 assert(*gc_succeeded, "sanity");
1819 return result;
1820 }
1821
1822 // In a G1 heap, we're supposed to keep allocation from failing by
1823 // incremental pauses. Therefore, at least for now, we'll favor
1824 // expansion over collection. (This might change in the future if we can
1825 // do something smarter than full collection to satisfy a failed alloc.)
1826 result = expand_and_allocate(word_size, context);
1827 if (result != NULL) {
1828 assert(*gc_succeeded, "sanity");
1829 return result;
1830 }
1831
1832 if (do_gc) {
1833 // Expansion didn't work, we'll try to do a Full GC.
1834 *gc_succeeded = do_collection(false, /* explicit_gc */
1835 clear_all_soft_refs,
1836 word_size);
1837 }
1838
1839 return NULL;
1840 }
1841
1842 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1843 AllocationContext_t context,
1844 bool* succeeded) {
1845 assert_at_safepoint(true /* should_be_vm_thread */);
1846
1847 // Attempts to allocate followed by Full GC.
1848 HeapWord* result =
1849 satisfy_failed_allocation_helper(word_size,
1850 context,
1851 true, /* do_gc */
1852 false, /* clear_all_soft_refs */
1853 false, /* expect_null_mutator_alloc_region */
1854 succeeded);
1855
1856 if (result != NULL || !*succeeded) {
1857 return result;
1858 }
1859
1860 // Attempts to allocate followed by Full GC that will collect all soft references.
1861 result = satisfy_failed_allocation_helper(word_size,
1862 context,
1863 true, /* do_gc */
1864 true, /* clear_all_soft_refs */
1865 true, /* expect_null_mutator_alloc_region */
1866 succeeded);
1867
1868 if (result != NULL || !*succeeded) {
1869 return result;
1870 }
1871
1872 // Attempts to allocate, no GC
1873 result = satisfy_failed_allocation_helper(word_size,
1874 context,
1875 false, /* do_gc */
1876 false, /* clear_all_soft_refs */
1877 true, /* expect_null_mutator_alloc_region */
1878 succeeded);
1879
1880 if (result != NULL) {
1881 assert(*succeeded, "sanity");
1882 return result;
1883 }
1884
1885 assert(!collector_policy()->should_clear_all_soft_refs(),
1886 "Flag should have been handled and cleared prior to this point");
1887
1888 // What else? We might try synchronous finalization later. If the total
1889 // space available is large enough for the allocation, then a more
1890 // complete compaction phase than we've tried so far might be
1891 // appropriate.
1892 assert(*succeeded, "sanity");
1893 return NULL;
1894 }
1895
1896 // Attempting to expand the heap sufficiently
1897 // to support an allocation of the given "word_size". If
1898 // successful, perform the allocation and return the address of the
1899 // allocated block, or else "NULL".
1900
1901 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1902 assert_at_safepoint(true /* should_be_vm_thread */);
1903
1904 verify_region_sets_optional();
1905
1906 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1907 ergo_verbose1(ErgoHeapSizing,
1908 "attempt heap expansion",
1909 ergo_format_reason("allocation request failed")
1910 ergo_format_byte("allocation request"),
1911 word_size * HeapWordSize);
1912 if (expand(expand_bytes)) {
1913 _hrm.verify_optional();
1914 verify_region_sets_optional();
1915 return attempt_allocation_at_safepoint(word_size,
1916 context,
1917 false /* expect_null_mutator_alloc_region */);
1918 }
1919 return NULL;
1920 }
1921
1922 bool G1CollectedHeap::expand(size_t expand_bytes) {
1923 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1924 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1925 HeapRegion::GrainBytes);
1926 ergo_verbose2(ErgoHeapSizing,
1927 "expand the heap",
1928 ergo_format_byte("requested expansion amount")
1929 ergo_format_byte("attempted expansion amount"),
1930 expand_bytes, aligned_expand_bytes);
1931
1932 if (is_maximal_no_gc()) {
1933 ergo_verbose0(ErgoHeapSizing,
1934 "did not expand the heap",
1935 ergo_format_reason("heap already fully expanded"));
1936 return false;
1937 }
1938
1939 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1940 assert(regions_to_expand > 0, "Must expand by at least one region");
1941
1942 uint expanded_by = _hrm.expand_by(regions_to_expand);
1943
1944 if (expanded_by > 0) {
1945 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1946 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1947 g1_policy()->record_new_heap_size(num_regions());
1948 } else {
1949 ergo_verbose0(ErgoHeapSizing,
1950 "did not expand the heap",
1951 ergo_format_reason("heap expansion operation failed"));
1952 // The expansion of the virtual storage space was unsuccessful.
1953 // Let's see if it was because we ran out of swap.
1954 if (G1ExitOnExpansionFailure &&
1955 _hrm.available() >= regions_to_expand) {
1956 // We had head room...
1957 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1958 }
1959 }
1960 return regions_to_expand > 0;
1961 }
1962
1963 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1964 size_t aligned_shrink_bytes =
1965 ReservedSpace::page_align_size_down(shrink_bytes);
1966 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1967 HeapRegion::GrainBytes);
1968 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1969
1970 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1971 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1972
1973 ergo_verbose3(ErgoHeapSizing,
1974 "shrink the heap",
1975 ergo_format_byte("requested shrinking amount")
1976 ergo_format_byte("aligned shrinking amount")
1977 ergo_format_byte("attempted shrinking amount"),
1978 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1979 if (num_regions_removed > 0) {
1980 g1_policy()->record_new_heap_size(num_regions());
1981 } else {
1982 ergo_verbose0(ErgoHeapSizing,
1983 "did not shrink the heap",
1984 ergo_format_reason("heap shrinking operation failed"));
1985 }
1986 }
1987
1988 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1989 verify_region_sets_optional();
1990
1991 // We should only reach here at the end of a Full GC which means we
1992 // should not not be holding to any GC alloc regions. The method
1993 // below will make sure of that and do any remaining clean up.
1994 _allocator->abandon_gc_alloc_regions();
1995
1996 // Instead of tearing down / rebuilding the free lists here, we
1997 // could instead use the remove_all_pending() method on free_list to
1998 // remove only the ones that we need to remove.
1999 tear_down_region_sets(true /* free_list_only */);
2000 shrink_helper(shrink_bytes);
2001 rebuild_region_sets(true /* free_list_only */);
2002
2003 _hrm.verify_optional();
2004 verify_region_sets_optional();
2005 }
2006
2007 // Public methods.
2008
2009 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
2010 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
2011 #endif // _MSC_VER
2012
2013
2014 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2015 CollectedHeap(),
2016 _g1_policy(policy_),
2017 _dirty_card_queue_set(false),
2018 _into_cset_dirty_card_queue_set(false),
2019 _is_alive_closure_cm(this),
2020 _is_alive_closure_stw(this),
2021 _ref_processor_cm(NULL),
2022 _ref_processor_stw(NULL),
2023 _bot_shared(NULL),
2024 _cg1r(NULL),
2025 _g1mm(NULL),
2026 _refine_cte_cl(NULL),
2027 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2028 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2029 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2030 _humongous_reclaim_candidates(),
2031 _has_humongous_reclaim_candidates(false),
2032 _archive_allocator(NULL),
2033 _free_regions_coming(false),
2034 _young_list(new YoungList(this)),
2035 _gc_time_stamp(0),
2036 _summary_bytes_used(0),
2037 _survivor_evac_stats(YoungPLABSize, PLABWeight),
2038 _old_evac_stats(OldPLABSize, PLABWeight),
2039 _expand_heap_after_alloc_failure(true),
2040 _old_marking_cycles_started(0),
2041 _old_marking_cycles_completed(0),
2042 _heap_summary_sent(false),
2043 _in_cset_fast_test(),
2044 _dirty_cards_region_list(NULL),
2045 _worker_cset_start_region(NULL),
2046 _worker_cset_start_region_time_stamp(NULL),
2047 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2048 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2049 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2050 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2051
2052 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2053 /* are_GC_task_threads */true,
2054 /* are_ConcurrentGC_threads */false);
2055 _workers->initialize_workers();
2056
2057 _allocator = G1Allocator::create_allocator(this);
2058 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2059
2060 // Override the default _filler_array_max_size so that no humongous filler
2061 // objects are created.
2062 _filler_array_max_size = _humongous_object_threshold_in_words;
2063
2064 uint n_queues = ParallelGCThreads;
2065 _task_queues = new RefToScanQueueSet(n_queues);
2066
2067 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2068 assert(n_rem_sets > 0, "Invariant.");
2069
2070 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2071 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2072 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2073
2074 for (uint i = 0; i < n_queues; i++) {
2075 RefToScanQueue* q = new RefToScanQueue();
2076 q->initialize();
2077 _task_queues->register_queue(i, q);
2078 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2079 }
2080 clear_cset_start_regions();
2081
2082 // Initialize the G1EvacuationFailureALot counters and flags.
2083 NOT_PRODUCT(reset_evacuation_should_fail();)
2084
2085 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2086 }
2087
2088 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2089 size_t size,
2090 size_t translation_factor) {
2091 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2092 // Allocate a new reserved space, preferring to use large pages.
2093 ReservedSpace rs(size, preferred_page_size);
2094 G1RegionToSpaceMapper* result =
2095 G1RegionToSpaceMapper::create_mapper(rs,
2096 size,
2097 rs.alignment(),
2098 HeapRegion::GrainBytes,
2099 translation_factor,
2100 mtGC);
2101 if (TracePageSizes) {
2102 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2103 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2104 }
2105 return result;
2106 }
2107
2108 jint G1CollectedHeap::initialize() {
2109 CollectedHeap::pre_initialize();
2110 os::enable_vtime();
2111
2112 G1Log::init();
2113
2114 // Necessary to satisfy locking discipline assertions.
2115
2116 MutexLocker x(Heap_lock);
2117
2118 // We have to initialize the printer before committing the heap, as
2119 // it will be used then.
2120 _hr_printer.set_active(G1PrintHeapRegions);
2121
2122 // While there are no constraints in the GC code that HeapWordSize
2123 // be any particular value, there are multiple other areas in the
2124 // system which believe this to be true (e.g. oop->object_size in some
2125 // cases incorrectly returns the size in wordSize units rather than
2126 // HeapWordSize).
2127 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2128
2129 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2130 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2131 size_t heap_alignment = collector_policy()->heap_alignment();
2132
2133 // Ensure that the sizes are properly aligned.
2134 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2135 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2136 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2137
2138 _refine_cte_cl = new RefineCardTableEntryClosure();
2139
2140 jint ecode = JNI_OK;
2141 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
2142 if (_cg1r == NULL) {
2143 return ecode;
2144 }
2145
2146 // Reserve the maximum.
2147
2148 // When compressed oops are enabled, the preferred heap base
2149 // is calculated by subtracting the requested size from the
2150 // 32Gb boundary and using the result as the base address for
2151 // heap reservation. If the requested size is not aligned to
2152 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2153 // into the ReservedHeapSpace constructor) then the actual
2154 // base of the reserved heap may end up differing from the
2155 // address that was requested (i.e. the preferred heap base).
2156 // If this happens then we could end up using a non-optimal
2157 // compressed oops mode.
2158
2159 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2160 heap_alignment);
2161
2162 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2163
2164 // Create the barrier set for the entire reserved region.
2165 G1SATBCardTableLoggingModRefBS* bs
2166 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2167 bs->initialize();
2168 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2169 set_barrier_set(bs);
2170
2171 // Also create a G1 rem set.
2172 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2173
2174 // Carve out the G1 part of the heap.
2175
2176 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2177 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2178 G1RegionToSpaceMapper* heap_storage =
2179 G1RegionToSpaceMapper::create_mapper(g1_rs,
2180 g1_rs.size(),
2181 page_size,
2182 HeapRegion::GrainBytes,
2183 1,
2184 mtJavaHeap);
2185 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2186 max_byte_size, page_size,
2187 heap_rs.base(),
2188 heap_rs.size());
2189 heap_storage->set_mapping_changed_listener(&_listener);
2190
2191 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2192 G1RegionToSpaceMapper* bot_storage =
2193 create_aux_memory_mapper("Block offset table",
2194 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2195 G1BlockOffsetSharedArray::heap_map_factor());
2196
2197 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2198 G1RegionToSpaceMapper* cardtable_storage =
2199 create_aux_memory_mapper("Card table",
2200 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2201 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2202
2203 G1RegionToSpaceMapper* card_counts_storage =
2204 create_aux_memory_mapper("Card counts table",
2205 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2206 G1CardCounts::heap_map_factor());
2207
2208 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2209 G1RegionToSpaceMapper* prev_bitmap_storage =
2210 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2211 G1RegionToSpaceMapper* next_bitmap_storage =
2212 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2213
2214 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2215 g1_barrier_set()->initialize(cardtable_storage);
2216 // Do later initialization work for concurrent refinement.
2217 _cg1r->init(card_counts_storage);
2218
2219 // 6843694 - ensure that the maximum region index can fit
2220 // in the remembered set structures.
2221 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2222 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2223
2224 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2225 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2226 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2227 "too many cards per region");
2228
2229 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2230
2231 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2232
2233 {
2234 HeapWord* start = _hrm.reserved().start();
2235 HeapWord* end = _hrm.reserved().end();
2236 size_t granularity = HeapRegion::GrainBytes;
2237
2238 _in_cset_fast_test.initialize(start, end, granularity);
2239 _humongous_reclaim_candidates.initialize(start, end, granularity);
2240 }
2241
2242 // Create the ConcurrentMark data structure and thread.
2243 // (Must do this late, so that "max_regions" is defined.)
2244 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2245 if (_cm == NULL || !_cm->completed_initialization()) {
2246 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2247 return JNI_ENOMEM;
2248 }
2249 _cmThread = _cm->cmThread();
2250
2251 // Initialize the from_card cache structure of HeapRegionRemSet.
2252 HeapRegionRemSet::init_heap(max_regions());
2253
2254 // Now expand into the initial heap size.
2255 if (!expand(init_byte_size)) {
2256 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2257 return JNI_ENOMEM;
2258 }
2259
2260 // Perform any initialization actions delegated to the policy.
2261 g1_policy()->init();
2262
2263 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2264 SATB_Q_FL_lock,
2265 G1SATBProcessCompletedThreshold,
2266 Shared_SATB_Q_lock);
2267
2268 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2269 DirtyCardQ_CBL_mon,
2270 DirtyCardQ_FL_lock,
2271 concurrent_g1_refine()->yellow_zone(),
2272 concurrent_g1_refine()->red_zone(),
2273 Shared_DirtyCardQ_lock);
2274
2275 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2276 DirtyCardQ_CBL_mon,
2277 DirtyCardQ_FL_lock,
2278 -1, // never trigger processing
2279 -1, // no limit on length
2280 Shared_DirtyCardQ_lock,
2281 &JavaThread::dirty_card_queue_set());
2282
2283 // Initialize the card queue set used to hold cards containing
2284 // references into the collection set.
2285 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2286 DirtyCardQ_CBL_mon,
2287 DirtyCardQ_FL_lock,
2288 -1, // never trigger processing
2289 -1, // no limit on length
2290 Shared_DirtyCardQ_lock,
2291 &JavaThread::dirty_card_queue_set());
2292
2293 // Here we allocate the dummy HeapRegion that is required by the
2294 // G1AllocRegion class.
2295 HeapRegion* dummy_region = _hrm.get_dummy_region();
2296
2297 // We'll re-use the same region whether the alloc region will
2298 // require BOT updates or not and, if it doesn't, then a non-young
2299 // region will complain that it cannot support allocations without
2300 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2301 dummy_region->set_eden();
2302 // Make sure it's full.
2303 dummy_region->set_top(dummy_region->end());
2304 G1AllocRegion::setup(this, dummy_region);
2305
2306 _allocator->init_mutator_alloc_region();
2307
2308 // Do create of the monitoring and management support so that
2309 // values in the heap have been properly initialized.
2310 _g1mm = new G1MonitoringSupport(this);
2311
2312 G1StringDedup::initialize();
2313
2314 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2315 for (uint i = 0; i < ParallelGCThreads; i++) {
2316 new (&_preserved_objs[i]) OopAndMarkOopStack();
2317 }
2318
2319 return JNI_OK;
2320 }
2321
2322 void G1CollectedHeap::stop() {
2323 // Stop all concurrent threads. We do this to make sure these threads
2324 // do not continue to execute and access resources (e.g. gclog_or_tty)
2325 // that are destroyed during shutdown.
2326 _cg1r->stop();
2327 _cmThread->stop();
2328 if (G1StringDedup::is_enabled()) {
2329 G1StringDedup::stop();
2330 }
2331 }
2332
2333 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2334 return HeapRegion::max_region_size();
2335 }
2336
2337 void G1CollectedHeap::post_initialize() {
2338 CollectedHeap::post_initialize();
2339 ref_processing_init();
2340 }
2341
2342 void G1CollectedHeap::ref_processing_init() {
2343 // Reference processing in G1 currently works as follows:
2344 //
2345 // * There are two reference processor instances. One is
2346 // used to record and process discovered references
2347 // during concurrent marking; the other is used to
2348 // record and process references during STW pauses
2349 // (both full and incremental).
2350 // * Both ref processors need to 'span' the entire heap as
2351 // the regions in the collection set may be dotted around.
2352 //
2353 // * For the concurrent marking ref processor:
2354 // * Reference discovery is enabled at initial marking.
2355 // * Reference discovery is disabled and the discovered
2356 // references processed etc during remarking.
2357 // * Reference discovery is MT (see below).
2358 // * Reference discovery requires a barrier (see below).
2359 // * Reference processing may or may not be MT
2360 // (depending on the value of ParallelRefProcEnabled
2361 // and ParallelGCThreads).
2362 // * A full GC disables reference discovery by the CM
2363 // ref processor and abandons any entries on it's
2364 // discovered lists.
2365 //
2366 // * For the STW processor:
2367 // * Non MT discovery is enabled at the start of a full GC.
2368 // * Processing and enqueueing during a full GC is non-MT.
2369 // * During a full GC, references are processed after marking.
2370 //
2371 // * Discovery (may or may not be MT) is enabled at the start
2372 // of an incremental evacuation pause.
2373 // * References are processed near the end of a STW evacuation pause.
2374 // * For both types of GC:
2375 // * Discovery is atomic - i.e. not concurrent.
2376 // * Reference discovery will not need a barrier.
2377
2378 MemRegion mr = reserved_region();
2379
2380 // Concurrent Mark ref processor
2381 _ref_processor_cm =
2382 new ReferenceProcessor(mr, // span
2383 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2384 // mt processing
2385 ParallelGCThreads,
2386 // degree of mt processing
2387 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2388 // mt discovery
2389 MAX2(ParallelGCThreads, ConcGCThreads),
2390 // degree of mt discovery
2391 false,
2392 // Reference discovery is not atomic
2393 &_is_alive_closure_cm);
2394 // is alive closure
2395 // (for efficiency/performance)
2396
2397 // STW ref processor
2398 _ref_processor_stw =
2399 new ReferenceProcessor(mr, // span
2400 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2401 // mt processing
2402 ParallelGCThreads,
2403 // degree of mt processing
2404 (ParallelGCThreads > 1),
2405 // mt discovery
2406 ParallelGCThreads,
2407 // degree of mt discovery
2408 true,
2409 // Reference discovery is atomic
2410 &_is_alive_closure_stw);
2411 // is alive closure
2412 // (for efficiency/performance)
2413 }
2414
2415 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2416 return g1_policy();
2417 }
2418
2419 size_t G1CollectedHeap::capacity() const {
2420 return _hrm.length() * HeapRegion::GrainBytes;
2421 }
2422
2423 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2424 assert(!hr->is_continues_humongous(), "pre-condition");
2425 hr->reset_gc_time_stamp();
2426 if (hr->is_starts_humongous()) {
2427 uint first_index = hr->hrm_index() + 1;
2428 uint last_index = hr->last_hc_index();
2429 for (uint i = first_index; i < last_index; i += 1) {
2430 HeapRegion* chr = region_at(i);
2431 assert(chr->is_continues_humongous(), "sanity");
2432 chr->reset_gc_time_stamp();
2433 }
2434 }
2435 }
2436
2437 #ifndef PRODUCT
2438
2439 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2440 private:
2441 unsigned _gc_time_stamp;
2442 bool _failures;
2443
2444 public:
2445 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2446 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2447
2448 virtual bool doHeapRegion(HeapRegion* hr) {
2449 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2450 if (_gc_time_stamp != region_gc_time_stamp) {
2451 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2452 "expected %d", HR_FORMAT_PARAMS(hr),
2453 region_gc_time_stamp, _gc_time_stamp);
2454 _failures = true;
2455 }
2456 return false;
2457 }
2458
2459 bool failures() { return _failures; }
2460 };
2461
2462 void G1CollectedHeap::check_gc_time_stamps() {
2463 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2464 heap_region_iterate(&cl);
2465 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2466 }
2467 #endif // PRODUCT
2468
2469 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2470 DirtyCardQueue* into_cset_dcq,
2471 bool concurrent,
2472 uint worker_i) {
2473 // Clean cards in the hot card cache
2474 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2475 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2476
2477 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2478 size_t n_completed_buffers = 0;
2479 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2480 n_completed_buffers++;
2481 }
2482 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2483 dcqs.clear_n_completed_buffers();
2484 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2485 }
2486
2487 // Computes the sum of the storage used by the various regions.
2488 size_t G1CollectedHeap::used() const {
2489 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2490 if (_archive_allocator != NULL) {
2491 result += _archive_allocator->used();
2492 }
2493 return result;
2494 }
2495
2496 size_t G1CollectedHeap::used_unlocked() const {
2497 return _summary_bytes_used;
2498 }
2499
2500 class SumUsedClosure: public HeapRegionClosure {
2501 size_t _used;
2502 public:
2503 SumUsedClosure() : _used(0) {}
2504 bool doHeapRegion(HeapRegion* r) {
2505 if (!r->is_continues_humongous()) {
2506 _used += r->used();
2507 }
2508 return false;
2509 }
2510 size_t result() { return _used; }
2511 };
2512
2513 size_t G1CollectedHeap::recalculate_used() const {
2514 double recalculate_used_start = os::elapsedTime();
2515
2516 SumUsedClosure blk;
2517 heap_region_iterate(&blk);
2518
2519 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2520 return blk.result();
2521 }
2522
2523 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2524 switch (cause) {
2525 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2526 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2527 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2528 case GCCause::_g1_humongous_allocation: return true;
2529 case GCCause::_update_allocation_context_stats_inc: return true;
2530 case GCCause::_wb_conc_mark: return true;
2531 default: return false;
2532 }
2533 }
2534
2535 #ifndef PRODUCT
2536 void G1CollectedHeap::allocate_dummy_regions() {
2537 // Let's fill up most of the region
2538 size_t word_size = HeapRegion::GrainWords - 1024;
2539 // And as a result the region we'll allocate will be humongous.
2540 guarantee(is_humongous(word_size), "sanity");
2541
2542 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2543 // Let's use the existing mechanism for the allocation
2544 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2545 AllocationContext::system());
2546 if (dummy_obj != NULL) {
2547 MemRegion mr(dummy_obj, word_size);
2548 CollectedHeap::fill_with_object(mr);
2549 } else {
2550 // If we can't allocate once, we probably cannot allocate
2551 // again. Let's get out of the loop.
2552 break;
2553 }
2554 }
2555 }
2556 #endif // !PRODUCT
2557
2558 void G1CollectedHeap::increment_old_marking_cycles_started() {
2559 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2560 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2561 "Wrong marking cycle count (started: %d, completed: %d)",
2562 _old_marking_cycles_started, _old_marking_cycles_completed);
2563
2564 _old_marking_cycles_started++;
2565 }
2566
2567 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2568 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2569
2570 // We assume that if concurrent == true, then the caller is a
2571 // concurrent thread that was joined the Suspendible Thread
2572 // Set. If there's ever a cheap way to check this, we should add an
2573 // assert here.
2574
2575 // Given that this method is called at the end of a Full GC or of a
2576 // concurrent cycle, and those can be nested (i.e., a Full GC can
2577 // interrupt a concurrent cycle), the number of full collections
2578 // completed should be either one (in the case where there was no
2579 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2580 // behind the number of full collections started.
2581
2582 // This is the case for the inner caller, i.e. a Full GC.
2583 assert(concurrent ||
2584 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2585 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2586 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2587 "is inconsistent with _old_marking_cycles_completed = %u",
2588 _old_marking_cycles_started, _old_marking_cycles_completed);
2589
2590 // This is the case for the outer caller, i.e. the concurrent cycle.
2591 assert(!concurrent ||
2592 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2593 "for outer caller (concurrent cycle): "
2594 "_old_marking_cycles_started = %u "
2595 "is inconsistent with _old_marking_cycles_completed = %u",
2596 _old_marking_cycles_started, _old_marking_cycles_completed);
2597
2598 _old_marking_cycles_completed += 1;
2599
2600 // We need to clear the "in_progress" flag in the CM thread before
2601 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2602 // is set) so that if a waiter requests another System.gc() it doesn't
2603 // incorrectly see that a marking cycle is still in progress.
2604 if (concurrent) {
2605 _cmThread->set_idle();
2606 }
2607
2608 // This notify_all() will ensure that a thread that called
2609 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2610 // and it's waiting for a full GC to finish will be woken up. It is
2611 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2612 FullGCCount_lock->notify_all();
2613 }
2614
2615 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
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 }
2622
2623 void G1CollectedHeap::register_concurrent_cycle_end() {
2624 if (collector_state()->concurrent_cycle_started()) {
2625 if (_cm->has_aborted()) {
2626 _gc_tracer_cm->report_concurrent_mode_failure();
2627 }
2628
2629 _gc_timer_cm->register_gc_end();
2630 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2631
2632 // Clear state variables to prepare for the next concurrent cycle.
2633 collector_state()->set_concurrent_cycle_started(false);
2634 _heap_summary_sent = false;
2635 }
2636 }
2637
2638 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2639 if (collector_state()->concurrent_cycle_started()) {
2640 // This function can be called when:
2641 // the cleanup pause is run
2642 // the concurrent cycle is aborted before the cleanup pause.
2643 // the concurrent cycle is aborted after the cleanup pause,
2644 // but before the concurrent cycle end has been registered.
2645 // Make sure that we only send the heap information once.
2646 if (!_heap_summary_sent) {
2647 trace_heap_after_gc(_gc_tracer_cm);
2648 _heap_summary_sent = true;
2649 }
2650 }
2651 }
2652
2653 void G1CollectedHeap::collect(GCCause::Cause cause) {
2654 assert_heap_not_locked();
2655
2656 uint gc_count_before;
2657 uint old_marking_count_before;
2658 uint full_gc_count_before;
2659 bool retry_gc;
2660
2661 do {
2662 retry_gc = false;
2663
2664 {
2665 MutexLocker ml(Heap_lock);
2666
2667 // Read the GC count while holding the Heap_lock
2668 gc_count_before = total_collections();
2669 full_gc_count_before = total_full_collections();
2670 old_marking_count_before = _old_marking_cycles_started;
2671 }
2672
2673 if (should_do_concurrent_full_gc(cause)) {
2674 // Schedule an initial-mark evacuation pause that will start a
2675 // concurrent cycle. We're setting word_size to 0 which means that
2676 // we are not requesting a post-GC allocation.
2677 VM_G1IncCollectionPause op(gc_count_before,
2678 0, /* word_size */
2679 true, /* should_initiate_conc_mark */
2680 g1_policy()->max_pause_time_ms(),
2681 cause);
2682 op.set_allocation_context(AllocationContext::current());
2683
2684 VMThread::execute(&op);
2685 if (!op.pause_succeeded()) {
2686 if (old_marking_count_before == _old_marking_cycles_started) {
2687 retry_gc = op.should_retry_gc();
2688 } else {
2689 // A Full GC happened while we were trying to schedule the
2690 // initial-mark GC. No point in starting a new cycle given
2691 // that the whole heap was collected anyway.
2692 }
2693
2694 if (retry_gc) {
2695 if (GC_locker::is_active_and_needs_gc()) {
2696 GC_locker::stall_until_clear();
2697 }
2698 }
2699 }
2700 } else {
2701 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2702 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2703
2704 // Schedule a standard evacuation pause. We're setting word_size
2705 // to 0 which means that we are not requesting a post-GC allocation.
2706 VM_G1IncCollectionPause op(gc_count_before,
2707 0, /* word_size */
2708 false, /* should_initiate_conc_mark */
2709 g1_policy()->max_pause_time_ms(),
2710 cause);
2711 VMThread::execute(&op);
2712 } else {
2713 // Schedule a Full GC.
2714 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2715 VMThread::execute(&op);
2716 }
2717 }
2718 } while (retry_gc);
2719 }
2720
2721 bool G1CollectedHeap::is_in(const void* p) const {
2722 if (_hrm.reserved().contains(p)) {
2723 // Given that we know that p is in the reserved space,
2724 // heap_region_containing_raw() should successfully
2725 // return the containing region.
2726 HeapRegion* hr = heap_region_containing_raw(p);
2727 return hr->is_in(p);
2728 } else {
2729 return false;
2730 }
2731 }
2732
2733 #ifdef ASSERT
2734 bool G1CollectedHeap::is_in_exact(const void* p) const {
2735 bool contains = reserved_region().contains(p);
2736 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2737 if (contains && available) {
2738 return true;
2739 } else {
2740 return false;
2741 }
2742 }
2743 #endif
2744
2745 bool G1CollectedHeap::obj_in_cs(oop obj) {
2746 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2747 return r != NULL && r->in_collection_set();
2748 }
2749
2750 // Iteration functions.
2751
2752 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2753
2754 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2755 ExtendedOopClosure* _cl;
2756 public:
2757 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2758 bool doHeapRegion(HeapRegion* r) {
2759 if (!r->is_continues_humongous()) {
2760 r->oop_iterate(_cl);
2761 }
2762 return false;
2763 }
2764 };
2765
2766 // Iterates an ObjectClosure over all objects within a HeapRegion.
2767
2768 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2769 ObjectClosure* _cl;
2770 public:
2771 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2772 bool doHeapRegion(HeapRegion* r) {
2773 if (!r->is_continues_humongous()) {
2774 r->object_iterate(_cl);
2775 }
2776 return false;
2777 }
2778 };
2779
2780 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2781 IterateObjectClosureRegionClosure blk(cl);
2782 heap_region_iterate(&blk);
2783 }
2784
2785 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2786 _hrm.iterate(cl);
2787 }
2788
2789 void
2790 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2791 uint worker_id,
2792 HeapRegionClaimer *hrclaimer,
2793 bool concurrent) const {
2794 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2795 }
2796
2797 // Clear the cached CSet starting regions and (more importantly)
2798 // the time stamps. Called when we reset the GC time stamp.
2799 void G1CollectedHeap::clear_cset_start_regions() {
2800 assert(_worker_cset_start_region != NULL, "sanity");
2801 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2802
2803 for (uint i = 0; i < ParallelGCThreads; i++) {
2804 _worker_cset_start_region[i] = NULL;
2805 _worker_cset_start_region_time_stamp[i] = 0;
2806 }
2807 }
2808
2809 // Given the id of a worker, obtain or calculate a suitable
2810 // starting region for iterating over the current collection set.
2811 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2812 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2813
2814 HeapRegion* result = NULL;
2815 unsigned gc_time_stamp = get_gc_time_stamp();
2816
2817 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2818 // Cached starting region for current worker was set
2819 // during the current pause - so it's valid.
2820 // Note: the cached starting heap region may be NULL
2821 // (when the collection set is empty).
2822 result = _worker_cset_start_region[worker_i];
2823 assert(result == NULL || result->in_collection_set(), "sanity");
2824 return result;
2825 }
2826
2827 // The cached entry was not valid so let's calculate
2828 // a suitable starting heap region for this worker.
2829
2830 // We want the parallel threads to start their collection
2831 // set iteration at different collection set regions to
2832 // avoid contention.
2833 // If we have:
2834 // n collection set regions
2835 // p threads
2836 // Then thread t will start at region floor ((t * n) / p)
2837
2838 result = g1_policy()->collection_set();
2839 uint cs_size = g1_policy()->cset_region_length();
2840 uint active_workers = workers()->active_workers();
2841
2842 uint end_ind = (cs_size * worker_i) / active_workers;
2843 uint start_ind = 0;
2844
2845 if (worker_i > 0 &&
2846 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2847 // Previous workers starting region is valid
2848 // so let's iterate from there
2849 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2850 result = _worker_cset_start_region[worker_i - 1];
2851 }
2852
2853 for (uint i = start_ind; i < end_ind; i++) {
2854 result = result->next_in_collection_set();
2855 }
2856
2857 // Note: the calculated starting heap region may be NULL
2858 // (when the collection set is empty).
2859 assert(result == NULL || result->in_collection_set(), "sanity");
2860 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2861 "should be updated only once per pause");
2862 _worker_cset_start_region[worker_i] = result;
2863 OrderAccess::storestore();
2864 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2865 return result;
2866 }
2867
2868 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2869 HeapRegion* r = g1_policy()->collection_set();
2870 while (r != NULL) {
2871 HeapRegion* next = r->next_in_collection_set();
2872 if (cl->doHeapRegion(r)) {
2873 cl->incomplete();
2874 return;
2875 }
2876 r = next;
2877 }
2878 }
2879
2880 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2881 HeapRegionClosure *cl) {
2882 if (r == NULL) {
2883 // The CSet is empty so there's nothing to do.
2884 return;
2885 }
2886
2887 assert(r->in_collection_set(),
2888 "Start region must be a member of the collection set.");
2889 HeapRegion* cur = r;
2890 while (cur != NULL) {
2891 HeapRegion* next = cur->next_in_collection_set();
2892 if (cl->doHeapRegion(cur) && false) {
2893 cl->incomplete();
2894 return;
2895 }
2896 cur = next;
2897 }
2898 cur = g1_policy()->collection_set();
2899 while (cur != r) {
2900 HeapRegion* next = cur->next_in_collection_set();
2901 if (cl->doHeapRegion(cur) && false) {
2902 cl->incomplete();
2903 return;
2904 }
2905 cur = next;
2906 }
2907 }
2908
2909 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2910 HeapRegion* result = _hrm.next_region_in_heap(from);
2911 while (result != NULL && result->is_pinned()) {
2912 result = _hrm.next_region_in_heap(result);
2913 }
2914 return result;
2915 }
2916
2917 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2918 HeapRegion* hr = heap_region_containing(addr);
2919 return hr->block_start(addr);
2920 }
2921
2922 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2923 HeapRegion* hr = heap_region_containing(addr);
2924 return hr->block_size(addr);
2925 }
2926
2927 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2928 HeapRegion* hr = heap_region_containing(addr);
2929 return hr->block_is_obj(addr);
2930 }
2931
2932 bool G1CollectedHeap::supports_tlab_allocation() const {
2933 return true;
2934 }
2935
2936 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2937 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2938 }
2939
2940 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2941 return young_list()->eden_used_bytes();
2942 }
2943
2944 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2945 // must be equal to the humongous object limit.
2946 size_t G1CollectedHeap::max_tlab_size() const {
2947 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2948 }
2949
2950 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2951 AllocationContext_t context = AllocationContext::current();
2952 return _allocator->unsafe_max_tlab_alloc(context);
2953 }
2954
2955 size_t G1CollectedHeap::max_capacity() const {
2956 return _hrm.reserved().byte_size();
2957 }
2958
2959 jlong G1CollectedHeap::millis_since_last_gc() {
2960 // assert(false, "NYI");
2961 return 0;
2962 }
2963
2964 void G1CollectedHeap::prepare_for_verify() {
2965 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2966 ensure_parsability(false);
2967 }
2968 g1_rem_set()->prepare_for_verify();
2969 }
2970
2971 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2972 VerifyOption vo) {
2973 switch (vo) {
2974 case VerifyOption_G1UsePrevMarking:
2975 return hr->obj_allocated_since_prev_marking(obj);
2976 case VerifyOption_G1UseNextMarking:
2977 return hr->obj_allocated_since_next_marking(obj);
2978 case VerifyOption_G1UseMarkWord:
2979 return false;
2980 default:
2981 ShouldNotReachHere();
2982 }
2983 return false; // keep some compilers happy
2984 }
2985
2986 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2987 switch (vo) {
2988 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2989 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2990 case VerifyOption_G1UseMarkWord: return NULL;
2991 default: ShouldNotReachHere();
2992 }
2993 return NULL; // keep some compilers happy
2994 }
2995
2996 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2997 switch (vo) {
2998 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2999 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3000 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3001 default: ShouldNotReachHere();
3002 }
3003 return false; // keep some compilers happy
3004 }
3005
3006 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3007 switch (vo) {
3008 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3009 case VerifyOption_G1UseNextMarking: return "NTAMS";
3010 case VerifyOption_G1UseMarkWord: return "NONE";
3011 default: ShouldNotReachHere();
3012 }
3013 return NULL; // keep some compilers happy
3014 }
3015
3016 class VerifyRootsClosure: public OopClosure {
3017 private:
3018 G1CollectedHeap* _g1h;
3019 VerifyOption _vo;
3020 bool _failures;
3021 public:
3022 // _vo == UsePrevMarking -> use "prev" marking information,
3023 // _vo == UseNextMarking -> use "next" marking information,
3024 // _vo == UseMarkWord -> use mark word from object header.
3025 VerifyRootsClosure(VerifyOption vo) :
3026 _g1h(G1CollectedHeap::heap()),
3027 _vo(vo),
3028 _failures(false) { }
3029
3030 bool failures() { return _failures; }
3031
3032 template <class T> void do_oop_nv(T* p) {
3033 T heap_oop = oopDesc::load_heap_oop(p);
3034 if (!oopDesc::is_null(heap_oop)) {
3035 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3036 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3037 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3038 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3039 if (_vo == VerifyOption_G1UseMarkWord) {
3040 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3041 }
3042 obj->print_on(gclog_or_tty);
3043 _failures = true;
3044 }
3045 }
3046 }
3047
3048 void do_oop(oop* p) { do_oop_nv(p); }
3049 void do_oop(narrowOop* p) { do_oop_nv(p); }
3050 };
3051
3052 class G1VerifyCodeRootOopClosure: public OopClosure {
3053 G1CollectedHeap* _g1h;
3054 OopClosure* _root_cl;
3055 nmethod* _nm;
3056 VerifyOption _vo;
3057 bool _failures;
3058
3059 template <class T> void do_oop_work(T* p) {
3060 // First verify that this root is live
3061 _root_cl->do_oop(p);
3062
3063 if (!G1VerifyHeapRegionCodeRoots) {
3064 // We're not verifying the code roots attached to heap region.
3065 return;
3066 }
3067
3068 // Don't check the code roots during marking verification in a full GC
3069 if (_vo == VerifyOption_G1UseMarkWord) {
3070 return;
3071 }
3072
3073 // Now verify that the current nmethod (which contains p) is
3074 // in the code root list of the heap region containing the
3075 // object referenced by p.
3076
3077 T heap_oop = oopDesc::load_heap_oop(p);
3078 if (!oopDesc::is_null(heap_oop)) {
3079 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3080
3081 // Now fetch the region containing the object
3082 HeapRegion* hr = _g1h->heap_region_containing(obj);
3083 HeapRegionRemSet* hrrs = hr->rem_set();
3084 // Verify that the strong code root list for this region
3085 // contains the nmethod
3086 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3087 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3088 "from nmethod " PTR_FORMAT " not in strong "
3089 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3090 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3091 _failures = true;
3092 }
3093 }
3094 }
3095
3096 public:
3097 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3098 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3099
3100 void do_oop(oop* p) { do_oop_work(p); }
3101 void do_oop(narrowOop* p) { do_oop_work(p); }
3102
3103 void set_nmethod(nmethod* nm) { _nm = nm; }
3104 bool failures() { return _failures; }
3105 };
3106
3107 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3108 G1VerifyCodeRootOopClosure* _oop_cl;
3109
3110 public:
3111 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3112 _oop_cl(oop_cl) {}
3113
3114 void do_code_blob(CodeBlob* cb) {
3115 nmethod* nm = cb->as_nmethod_or_null();
3116 if (nm != NULL) {
3117 _oop_cl->set_nmethod(nm);
3118 nm->oops_do(_oop_cl);
3119 }
3120 }
3121 };
3122
3123 class YoungRefCounterClosure : public OopClosure {
3124 G1CollectedHeap* _g1h;
3125 int _count;
3126 public:
3127 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3128 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3129 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3130
3131 int count() { return _count; }
3132 void reset_count() { _count = 0; };
3133 };
3134
3135 class VerifyKlassClosure: public KlassClosure {
3136 YoungRefCounterClosure _young_ref_counter_closure;
3137 OopClosure *_oop_closure;
3138 public:
3139 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3140 void do_klass(Klass* k) {
3141 k->oops_do(_oop_closure);
3142
3143 _young_ref_counter_closure.reset_count();
3144 k->oops_do(&_young_ref_counter_closure);
3145 if (_young_ref_counter_closure.count() > 0) {
3146 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
3147 }
3148 }
3149 };
3150
3151 class VerifyLivenessOopClosure: public OopClosure {
3152 G1CollectedHeap* _g1h;
3153 VerifyOption _vo;
3154 public:
3155 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3156 _g1h(g1h), _vo(vo)
3157 { }
3158 void do_oop(narrowOop *p) { do_oop_work(p); }
3159 void do_oop( oop *p) { do_oop_work(p); }
3160
3161 template <class T> void do_oop_work(T *p) {
3162 oop obj = oopDesc::load_decode_heap_oop(p);
3163 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3164 "Dead object referenced by a not dead object");
3165 }
3166 };
3167
3168 class VerifyObjsInRegionClosure: public ObjectClosure {
3169 private:
3170 G1CollectedHeap* _g1h;
3171 size_t _live_bytes;
3172 HeapRegion *_hr;
3173 VerifyOption _vo;
3174 public:
3175 // _vo == UsePrevMarking -> use "prev" marking information,
3176 // _vo == UseNextMarking -> use "next" marking information,
3177 // _vo == UseMarkWord -> use mark word from object header.
3178 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3179 : _live_bytes(0), _hr(hr), _vo(vo) {
3180 _g1h = G1CollectedHeap::heap();
3181 }
3182 void do_object(oop o) {
3183 VerifyLivenessOopClosure isLive(_g1h, _vo);
3184 assert(o != NULL, "Huh?");
3185 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3186 // If the object is alive according to the mark word,
3187 // then verify that the marking information agrees.
3188 // Note we can't verify the contra-positive of the
3189 // above: if the object is dead (according to the mark
3190 // word), it may not be marked, or may have been marked
3191 // but has since became dead, or may have been allocated
3192 // since the last marking.
3193 if (_vo == VerifyOption_G1UseMarkWord) {
3194 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3195 }
3196
3197 o->oop_iterate_no_header(&isLive);
3198 if (!_hr->obj_allocated_since_prev_marking(o)) {
3199 size_t obj_size = o->size(); // Make sure we don't overflow
3200 _live_bytes += (obj_size * HeapWordSize);
3201 }
3202 }
3203 }
3204 size_t live_bytes() { return _live_bytes; }
3205 };
3206
3207 class VerifyArchiveOopClosure: public OopClosure {
3208 public:
3209 VerifyArchiveOopClosure(HeapRegion *hr) { }
3210 void do_oop(narrowOop *p) { do_oop_work(p); }
3211 void do_oop( oop *p) { do_oop_work(p); }
3212
3213 template <class T> void do_oop_work(T *p) {
3214 oop obj = oopDesc::load_decode_heap_oop(p);
3215 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3216 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3217 p2i(p), p2i(obj));
3218 }
3219 };
3220
3221 class VerifyArchiveRegionClosure: public ObjectClosure {
3222 public:
3223 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3224 // Verify that all object pointers are to archive regions.
3225 void do_object(oop o) {
3226 VerifyArchiveOopClosure checkOop(NULL);
3227 assert(o != NULL, "Should not be here for NULL oops");
3228 o->oop_iterate_no_header(&checkOop);
3229 }
3230 };
3231
3232 class VerifyRegionClosure: public HeapRegionClosure {
3233 private:
3234 bool _par;
3235 VerifyOption _vo;
3236 bool _failures;
3237 public:
3238 // _vo == UsePrevMarking -> use "prev" marking information,
3239 // _vo == UseNextMarking -> use "next" marking information,
3240 // _vo == UseMarkWord -> use mark word from object header.
3241 VerifyRegionClosure(bool par, VerifyOption vo)
3242 : _par(par),
3243 _vo(vo),
3244 _failures(false) {}
3245
3246 bool failures() {
3247 return _failures;
3248 }
3249
3250 bool doHeapRegion(HeapRegion* r) {
3251 // For archive regions, verify there are no heap pointers to
3252 // non-pinned regions. For all others, verify liveness info.
3253 if (r->is_archive()) {
3254 VerifyArchiveRegionClosure verify_oop_pointers(r);
3255 r->object_iterate(&verify_oop_pointers);
3256 return true;
3257 }
3258 if (!r->is_continues_humongous()) {
3259 bool failures = false;
3260 r->verify(_vo, &failures);
3261 if (failures) {
3262 _failures = true;
3263 } else {
3264 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3265 r->object_iterate(¬_dead_yet_cl);
3266 if (_vo != VerifyOption_G1UseNextMarking) {
3267 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3268 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3269 "max_live_bytes " SIZE_FORMAT " "
3270 "< calculated " SIZE_FORMAT,
3271 p2i(r->bottom()), p2i(r->end()),
3272 r->max_live_bytes(),
3273 not_dead_yet_cl.live_bytes());
3274 _failures = true;
3275 }
3276 } else {
3277 // When vo == UseNextMarking we cannot currently do a sanity
3278 // check on the live bytes as the calculation has not been
3279 // finalized yet.
3280 }
3281 }
3282 }
3283 return false; // stop the region iteration if we hit a failure
3284 }
3285 };
3286
3287 // This is the task used for parallel verification of the heap regions
3288
3289 class G1ParVerifyTask: public AbstractGangTask {
3290 private:
3291 G1CollectedHeap* _g1h;
3292 VerifyOption _vo;
3293 bool _failures;
3294 HeapRegionClaimer _hrclaimer;
3295
3296 public:
3297 // _vo == UsePrevMarking -> use "prev" marking information,
3298 // _vo == UseNextMarking -> use "next" marking information,
3299 // _vo == UseMarkWord -> use mark word from object header.
3300 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3301 AbstractGangTask("Parallel verify task"),
3302 _g1h(g1h),
3303 _vo(vo),
3304 _failures(false),
3305 _hrclaimer(g1h->workers()->active_workers()) {}
3306
3307 bool failures() {
3308 return _failures;
3309 }
3310
3311 void work(uint worker_id) {
3312 HandleMark hm;
3313 VerifyRegionClosure blk(true, _vo);
3314 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3315 if (blk.failures()) {
3316 _failures = true;
3317 }
3318 }
3319 };
3320
3321 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3322 if (SafepointSynchronize::is_at_safepoint()) {
3323 assert(Thread::current()->is_VM_thread(),
3324 "Expected to be executed serially by the VM thread at this point");
3325
3326 if (!silent) { gclog_or_tty->print("Roots "); }
3327 VerifyRootsClosure rootsCl(vo);
3328 VerifyKlassClosure klassCl(this, &rootsCl);
3329 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3330
3331 // We apply the relevant closures to all the oops in the
3332 // system dictionary, class loader data graph, the string table
3333 // and the nmethods in the code cache.
3334 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3335 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3336
3337 {
3338 G1RootProcessor root_processor(this, 1);
3339 root_processor.process_all_roots(&rootsCl,
3340 &cldCl,
3341 &blobsCl);
3342 }
3343
3344 bool failures = rootsCl.failures() || codeRootsCl.failures();
3345
3346 if (vo != VerifyOption_G1UseMarkWord) {
3347 // If we're verifying during a full GC then the region sets
3348 // will have been torn down at the start of the GC. Therefore
3349 // verifying the region sets will fail. So we only verify
3350 // the region sets when not in a full GC.
3351 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3352 verify_region_sets();
3353 }
3354
3355 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3356 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3357
3358 G1ParVerifyTask task(this, vo);
3359 workers()->run_task(&task);
3360 if (task.failures()) {
3361 failures = true;
3362 }
3363
3364 } else {
3365 VerifyRegionClosure blk(false, vo);
3366 heap_region_iterate(&blk);
3367 if (blk.failures()) {
3368 failures = true;
3369 }
3370 }
3371
3372 if (G1StringDedup::is_enabled()) {
3373 if (!silent) gclog_or_tty->print("StrDedup ");
3374 G1StringDedup::verify();
3375 }
3376
3377 if (failures) {
3378 gclog_or_tty->print_cr("Heap:");
3379 // It helps to have the per-region information in the output to
3380 // help us track down what went wrong. This is why we call
3381 // print_extended_on() instead of print_on().
3382 print_extended_on(gclog_or_tty);
3383 gclog_or_tty->cr();
3384 gclog_or_tty->flush();
3385 }
3386 guarantee(!failures, "there should not have been any failures");
3387 } else {
3388 if (!silent) {
3389 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3390 if (G1StringDedup::is_enabled()) {
3391 gclog_or_tty->print(", StrDedup");
3392 }
3393 gclog_or_tty->print(") ");
3394 }
3395 }
3396 }
3397
3398 void G1CollectedHeap::verify(bool silent) {
3399 verify(silent, VerifyOption_G1UsePrevMarking);
3400 }
3401
3402 double G1CollectedHeap::verify(bool guard, const char* msg) {
3403 double verify_time_ms = 0.0;
3404
3405 if (guard && total_collections() >= VerifyGCStartAt) {
3406 double verify_start = os::elapsedTime();
3407 HandleMark hm; // Discard invalid handles created during verification
3408 prepare_for_verify();
3409 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3410 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3411 }
3412
3413 return verify_time_ms;
3414 }
3415
3416 void G1CollectedHeap::verify_before_gc() {
3417 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3418 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3419 }
3420
3421 void G1CollectedHeap::verify_after_gc() {
3422 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3423 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3424 }
3425
3426 class PrintRegionClosure: public HeapRegionClosure {
3427 outputStream* _st;
3428 public:
3429 PrintRegionClosure(outputStream* st) : _st(st) {}
3430 bool doHeapRegion(HeapRegion* r) {
3431 r->print_on(_st);
3432 return false;
3433 }
3434 };
3435
3436 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3437 const HeapRegion* hr,
3438 const VerifyOption vo) const {
3439 switch (vo) {
3440 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3441 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3442 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3443 default: ShouldNotReachHere();
3444 }
3445 return false; // keep some compilers happy
3446 }
3447
3448 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3449 const VerifyOption vo) const {
3450 switch (vo) {
3451 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3452 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3453 case VerifyOption_G1UseMarkWord: {
3454 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3455 return !obj->is_gc_marked() && !hr->is_archive();
3456 }
3457 default: ShouldNotReachHere();
3458 }
3459 return false; // keep some compilers happy
3460 }
3461
3462 void G1CollectedHeap::print_on(outputStream* st) const {
3463 st->print(" %-20s", "garbage-first heap");
3464 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3465 capacity()/K, used_unlocked()/K);
3466 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3467 p2i(_hrm.reserved().start()),
3468 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3469 p2i(_hrm.reserved().end()));
3470 st->cr();
3471 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3472 uint young_regions = _young_list->length();
3473 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3474 (size_t) young_regions * HeapRegion::GrainBytes / K);
3475 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3476 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3477 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3478 st->cr();
3479 MetaspaceAux::print_on(st);
3480 }
3481
3482 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3483 print_on(st);
3484
3485 // Print the per-region information.
3486 st->cr();
3487 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3488 "HS=humongous(starts), HC=humongous(continues), "
3489 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3490 "PTAMS=previous top-at-mark-start, "
3491 "NTAMS=next top-at-mark-start)");
3492 PrintRegionClosure blk(st);
3493 heap_region_iterate(&blk);
3494 }
3495
3496 void G1CollectedHeap::print_on_error(outputStream* st) const {
3497 this->CollectedHeap::print_on_error(st);
3498
3499 if (_cm != NULL) {
3500 st->cr();
3501 _cm->print_on_error(st);
3502 }
3503 }
3504
3505 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3506 workers()->print_worker_threads_on(st);
3507 _cmThread->print_on(st);
3508 st->cr();
3509 _cm->print_worker_threads_on(st);
3510 _cg1r->print_worker_threads_on(st);
3511 if (G1StringDedup::is_enabled()) {
3512 G1StringDedup::print_worker_threads_on(st);
3513 }
3514 }
3515
3516 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3517 workers()->threads_do(tc);
3518 tc->do_thread(_cmThread);
3519 _cg1r->threads_do(tc);
3520 if (G1StringDedup::is_enabled()) {
3521 G1StringDedup::threads_do(tc);
3522 }
3523 }
3524
3525 void G1CollectedHeap::print_tracing_info() const {
3526 // We'll overload this to mean "trace GC pause statistics."
3527 if (TraceYoungGenTime || TraceOldGenTime) {
3528 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3529 // to that.
3530 g1_policy()->print_tracing_info();
3531 }
3532 if (G1SummarizeRSetStats) {
3533 g1_rem_set()->print_summary_info();
3534 }
3535 if (G1SummarizeConcMark) {
3536 concurrent_mark()->print_summary_info();
3537 }
3538 g1_policy()->print_yg_surv_rate_info();
3539 }
3540
3541 #ifndef PRODUCT
3542 // Helpful for debugging RSet issues.
3543
3544 class PrintRSetsClosure : public HeapRegionClosure {
3545 private:
3546 const char* _msg;
3547 size_t _occupied_sum;
3548
3549 public:
3550 bool doHeapRegion(HeapRegion* r) {
3551 HeapRegionRemSet* hrrs = r->rem_set();
3552 size_t occupied = hrrs->occupied();
3553 _occupied_sum += occupied;
3554
3555 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3556 HR_FORMAT_PARAMS(r));
3557 if (occupied == 0) {
3558 gclog_or_tty->print_cr(" RSet is empty");
3559 } else {
3560 hrrs->print();
3561 }
3562 gclog_or_tty->print_cr("----------");
3563 return false;
3564 }
3565
3566 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3567 gclog_or_tty->cr();
3568 gclog_or_tty->print_cr("========================================");
3569 gclog_or_tty->print_cr("%s", msg);
3570 gclog_or_tty->cr();
3571 }
3572
3573 ~PrintRSetsClosure() {
3574 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3575 gclog_or_tty->print_cr("========================================");
3576 gclog_or_tty->cr();
3577 }
3578 };
3579
3580 void G1CollectedHeap::print_cset_rsets() {
3581 PrintRSetsClosure cl("Printing CSet RSets");
3582 collection_set_iterate(&cl);
3583 }
3584
3585 void G1CollectedHeap::print_all_rsets() {
3586 PrintRSetsClosure cl("Printing All RSets");;
3587 heap_region_iterate(&cl);
3588 }
3589 #endif // PRODUCT
3590
3591 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3592 YoungList* young_list = heap()->young_list();
3593
3594 size_t eden_used_bytes = young_list->eden_used_bytes();
3595 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3596
3597 size_t eden_capacity_bytes =
3598 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3599
3600 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3601 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3602 }
3603
3604 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3605 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3606 stats->unused(), stats->used(), stats->region_end_waste(),
3607 stats->regions_filled(), stats->direct_allocated(),
3608 stats->failure_used(), stats->failure_waste());
3609 }
3610
3611 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3612 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3613 gc_tracer->report_gc_heap_summary(when, heap_summary);
3614
3615 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3616 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3617 }
3618
3619
3620 G1CollectedHeap* G1CollectedHeap::heap() {
3621 CollectedHeap* heap = Universe::heap();
3622 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3623 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3624 return (G1CollectedHeap*)heap;
3625 }
3626
3627 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3628 // always_do_update_barrier = false;
3629 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3630 // Fill TLAB's and such
3631 accumulate_statistics_all_tlabs();
3632 ensure_parsability(true);
3633
3634 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3635 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3636 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3637 }
3638 }
3639
3640 void G1CollectedHeap::gc_epilogue(bool full) {
3641
3642 if (G1SummarizeRSetStats &&
3643 (G1SummarizeRSetStatsPeriod > 0) &&
3644 // we are at the end of the GC. Total collections has already been increased.
3645 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3646 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3647 }
3648
3649 // FIXME: what is this about?
3650 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3651 // is set.
3652 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3653 "derived pointer present"));
3654 // always_do_update_barrier = true;
3655
3656 resize_all_tlabs();
3657 allocation_context_stats().update(full);
3658
3659 // We have just completed a GC. Update the soft reference
3660 // policy with the new heap occupancy
3661 Universe::update_heap_info_at_gc();
3662 }
3663
3664 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3665 uint gc_count_before,
3666 bool* succeeded,
3667 GCCause::Cause gc_cause) {
3668 assert_heap_not_locked_and_not_at_safepoint();
3669 g1_policy()->record_stop_world_start();
3670 VM_G1IncCollectionPause op(gc_count_before,
3671 word_size,
3672 false, /* should_initiate_conc_mark */
3673 g1_policy()->max_pause_time_ms(),
3674 gc_cause);
3675
3676 op.set_allocation_context(AllocationContext::current());
3677 VMThread::execute(&op);
3678
3679 HeapWord* result = op.result();
3680 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3681 assert(result == NULL || ret_succeeded,
3682 "the result should be NULL if the VM did not succeed");
3683 *succeeded = ret_succeeded;
3684
3685 assert_heap_not_locked();
3686 return result;
3687 }
3688
3689 void
3690 G1CollectedHeap::doConcurrentMark() {
3691 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3692 if (!_cmThread->in_progress()) {
3693 _cmThread->set_started();
3694 CGC_lock->notify();
3695 }
3696 }
3697
3698 size_t G1CollectedHeap::pending_card_num() {
3699 size_t extra_cards = 0;
3700 JavaThread *curr = Threads::first();
3701 while (curr != NULL) {
3702 DirtyCardQueue& dcq = curr->dirty_card_queue();
3703 extra_cards += dcq.size();
3704 curr = curr->next();
3705 }
3706 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3707 size_t buffer_size = dcqs.buffer_size();
3708 size_t buffer_num = dcqs.completed_buffers_num();
3709
3710 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3711 // in bytes - not the number of 'entries'. We need to convert
3712 // into a number of cards.
3713 return (buffer_size * buffer_num + extra_cards) / oopSize;
3714 }
3715
3716 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3717 private:
3718 size_t _total_humongous;
3719 size_t _candidate_humongous;
3720
3721 DirtyCardQueue _dcq;
3722
3723 // We don't nominate objects with many remembered set entries, on
3724 // the assumption that such objects are likely still live.
3725 bool is_remset_small(HeapRegion* region) const {
3726 HeapRegionRemSet* const rset = region->rem_set();
3727 return G1EagerReclaimHumongousObjectsWithStaleRefs
3728 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3729 : rset->is_empty();
3730 }
3731
3732 bool is_typeArray_region(HeapRegion* region) const {
3733 return oop(region->bottom())->is_typeArray();
3734 }
3735
3736 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3737 assert(region->is_starts_humongous(), "Must start a humongous object");
3738
3739 // Candidate selection must satisfy the following constraints
3740 // while concurrent marking is in progress:
3741 //
3742 // * In order to maintain SATB invariants, an object must not be
3743 // reclaimed if it was allocated before the start of marking and
3744 // has not had its references scanned. Such an object must have
3745 // its references (including type metadata) scanned to ensure no
3746 // live objects are missed by the marking process. Objects
3747 // allocated after the start of concurrent marking don't need to
3748 // be scanned.
3749 //
3750 // * An object must not be reclaimed if it is on the concurrent
3751 // mark stack. Objects allocated after the start of concurrent
3752 // marking are never pushed on the mark stack.
3753 //
3754 // Nominating only objects allocated after the start of concurrent
3755 // marking is sufficient to meet both constraints. This may miss
3756 // some objects that satisfy the constraints, but the marking data
3757 // structures don't support efficiently performing the needed
3758 // additional tests or scrubbing of the mark stack.
3759 //
3760 // However, we presently only nominate is_typeArray() objects.
3761 // A humongous object containing references induces remembered
3762 // set entries on other regions. In order to reclaim such an
3763 // object, those remembered sets would need to be cleaned up.
3764 //
3765 // We also treat is_typeArray() objects specially, allowing them
3766 // to be reclaimed even if allocated before the start of
3767 // concurrent mark. For this we rely on mark stack insertion to
3768 // exclude is_typeArray() objects, preventing reclaiming an object
3769 // that is in the mark stack. We also rely on the metadata for
3770 // such objects to be built-in and so ensured to be kept live.
3771 // Frequent allocation and drop of large binary blobs is an
3772 // important use case for eager reclaim, and this special handling
3773 // may reduce needed headroom.
3774
3775 return is_typeArray_region(region) && is_remset_small(region);
3776 }
3777
3778 public:
3779 RegisterHumongousWithInCSetFastTestClosure()
3780 : _total_humongous(0),
3781 _candidate_humongous(0),
3782 _dcq(&JavaThread::dirty_card_queue_set()) {
3783 }
3784
3785 virtual bool doHeapRegion(HeapRegion* r) {
3786 if (!r->is_starts_humongous()) {
3787 return false;
3788 }
3789 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3790
3791 bool is_candidate = humongous_region_is_candidate(g1h, r);
3792 uint rindex = r->hrm_index();
3793 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3794 if (is_candidate) {
3795 _candidate_humongous++;
3796 g1h->register_humongous_region_with_cset(rindex);
3797 // Is_candidate already filters out humongous object with large remembered sets.
3798 // If we have a humongous object with a few remembered sets, we simply flush these
3799 // remembered set entries into the DCQS. That will result in automatic
3800 // re-evaluation of their remembered set entries during the following evacuation
3801 // phase.
3802 if (!r->rem_set()->is_empty()) {
3803 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3804 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3805 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3806 HeapRegionRemSetIterator hrrs(r->rem_set());
3807 size_t card_index;
3808 while (hrrs.has_next(card_index)) {
3809 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3810 // The remembered set might contain references to already freed
3811 // regions. Filter out such entries to avoid failing card table
3812 // verification.
3813 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3814 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3815 *card_ptr = CardTableModRefBS::dirty_card_val();
3816 _dcq.enqueue(card_ptr);
3817 }
3818 }
3819 }
3820 r->rem_set()->clear_locked();
3821 }
3822 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3823 }
3824 _total_humongous++;
3825
3826 return false;
3827 }
3828
3829 size_t total_humongous() const { return _total_humongous; }
3830 size_t candidate_humongous() const { return _candidate_humongous; }
3831
3832 void flush_rem_set_entries() { _dcq.flush(); }
3833 };
3834
3835 void G1CollectedHeap::register_humongous_regions_with_cset() {
3836 if (!G1EagerReclaimHumongousObjects) {
3837 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3838 return;
3839 }
3840 double time = os::elapsed_counter();
3841
3842 // Collect reclaim candidate information and register candidates with cset.
3843 RegisterHumongousWithInCSetFastTestClosure cl;
3844 heap_region_iterate(&cl);
3845
3846 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3847 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3848 cl.total_humongous(),
3849 cl.candidate_humongous());
3850 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3851
3852 // Finally flush all remembered set entries to re-check into the global DCQS.
3853 cl.flush_rem_set_entries();
3854 }
3855
3856 #ifdef ASSERT
3857 class VerifyCSetClosure: public HeapRegionClosure {
3858 public:
3859 bool doHeapRegion(HeapRegion* hr) {
3860 // Here we check that the CSet region's RSet is ready for parallel
3861 // iteration. The fields that we'll verify are only manipulated
3862 // when the region is part of a CSet and is collected. Afterwards,
3863 // we reset these fields when we clear the region's RSet (when the
3864 // region is freed) so they are ready when the region is
3865 // re-allocated. The only exception to this is if there's an
3866 // evacuation failure and instead of freeing the region we leave
3867 // it in the heap. In that case, we reset these fields during
3868 // evacuation failure handling.
3869 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3870
3871 // Here's a good place to add any other checks we'd like to
3872 // perform on CSet regions.
3873 return false;
3874 }
3875 };
3876 #endif // ASSERT
3877
3878 uint G1CollectedHeap::num_task_queues() const {
3879 return _task_queues->size();
3880 }
3881
3882 #if TASKQUEUE_STATS
3883 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3884 st->print_raw_cr("GC Task Stats");
3885 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3886 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3887 }
3888
3889 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3890 print_taskqueue_stats_hdr(st);
3891
3892 TaskQueueStats totals;
3893 const uint n = num_task_queues();
3894 for (uint i = 0; i < n; ++i) {
3895 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3896 totals += task_queue(i)->stats;
3897 }
3898 st->print_raw("tot "); totals.print(st); st->cr();
3899
3900 DEBUG_ONLY(totals.verify());
3901 }
3902
3903 void G1CollectedHeap::reset_taskqueue_stats() {
3904 const uint n = num_task_queues();
3905 for (uint i = 0; i < n; ++i) {
3906 task_queue(i)->stats.reset();
3907 }
3908 }
3909 #endif // TASKQUEUE_STATS
3910
3911 void G1CollectedHeap::log_gc_header() {
3912 if (!G1Log::fine()) {
3913 return;
3914 }
3915
3916 gclog_or_tty->gclog_stamp();
3917
3918 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3919 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3920 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3921
3922 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3923 }
3924
3925 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3926 if (!G1Log::fine()) {
3927 return;
3928 }
3929
3930 if (G1Log::finer()) {
3931 if (evacuation_failed()) {
3932 gclog_or_tty->print(" (to-space exhausted)");
3933 }
3934 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3935 g1_policy()->phase_times()->note_gc_end();
3936 g1_policy()->phase_times()->print(pause_time_sec);
3937 g1_policy()->print_detailed_heap_transition();
3938 } else {
3939 if (evacuation_failed()) {
3940 gclog_or_tty->print("--");
3941 }
3942 g1_policy()->print_heap_transition();
3943 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3944 }
3945 gclog_or_tty->flush();
3946 }
3947
3948 void G1CollectedHeap::wait_for_root_region_scanning() {
3949 double scan_wait_start = os::elapsedTime();
3950 // We have to wait until the CM threads finish scanning the
3951 // root regions as it's the only way to ensure that all the
3952 // objects on them have been correctly scanned before we start
3953 // moving them during the GC.
3954 bool waited = _cm->root_regions()->wait_until_scan_finished();
3955 double wait_time_ms = 0.0;
3956 if (waited) {
3957 double scan_wait_end = os::elapsedTime();
3958 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3959 }
3960 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3961 }
3962
3963 bool
3964 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3965 assert_at_safepoint(true /* should_be_vm_thread */);
3966 guarantee(!is_gc_active(), "collection is not reentrant");
3967
3968 if (GC_locker::check_active_before_gc()) {
3969 return false;
3970 }
3971
3972 _gc_timer_stw->register_gc_start();
3973
3974 GCIdMark gc_id_mark;
3975 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3976
3977 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3978 ResourceMark rm;
3979
3980 wait_for_root_region_scanning();
3981
3982 G1Log::update_level();
3983 print_heap_before_gc();
3984 trace_heap_before_gc(_gc_tracer_stw);
3985
3986 verify_region_sets_optional();
3987 verify_dirty_young_regions();
3988
3989 // This call will decide whether this pause is an initial-mark
3990 // pause. If it is, during_initial_mark_pause() will return true
3991 // for the duration of this pause.
3992 g1_policy()->decide_on_conc_mark_initiation();
3993
3994 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3995 assert(!collector_state()->during_initial_mark_pause() ||
3996 collector_state()->gcs_are_young(), "sanity");
3997
3998 // We also do not allow mixed GCs during marking.
3999 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4000
4001 // Record whether this pause is an initial mark. When the current
4002 // thread has completed its logging output and it's safe to signal
4003 // the CM thread, the flag's value in the policy has been reset.
4004 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4005
4006 // Inner scope for scope based logging, timers, and stats collection
4007 {
4008 EvacuationInfo evacuation_info;
4009
4010 if (collector_state()->during_initial_mark_pause()) {
4011 // We are about to start a marking cycle, so we increment the
4012 // full collection counter.
4013 increment_old_marking_cycles_started();
4014 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4015 }
4016
4017 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4018
4019 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4020
4021 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4022 workers()->active_workers(),
4023 Threads::number_of_non_daemon_threads());
4024 workers()->set_active_workers(active_workers);
4025
4026 double pause_start_sec = os::elapsedTime();
4027 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4028 log_gc_header();
4029
4030 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4031 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4032
4033 // If the secondary_free_list is not empty, append it to the
4034 // free_list. No need to wait for the cleanup operation to finish;
4035 // the region allocation code will check the secondary_free_list
4036 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4037 // set, skip this step so that the region allocation code has to
4038 // get entries from the secondary_free_list.
4039 if (!G1StressConcRegionFreeing) {
4040 append_secondary_free_list_if_not_empty_with_lock();
4041 }
4042
4043 assert(check_young_list_well_formed(), "young list should be well formed");
4044
4045 // Don't dynamically change the number of GC threads this early. A value of
4046 // 0 is used to indicate serial work. When parallel work is done,
4047 // it will be set.
4048
4049 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4050 IsGCActiveMark x;
4051
4052 gc_prologue(false);
4053 increment_total_collections(false /* full gc */);
4054 increment_gc_time_stamp();
4055
4056 verify_before_gc();
4057
4058 check_bitmaps("GC Start");
4059
4060 COMPILER2_PRESENT(DerivedPointerTable::clear());
4061
4062 // Please see comment in g1CollectedHeap.hpp and
4063 // G1CollectedHeap::ref_processing_init() to see how
4064 // reference processing currently works in G1.
4065
4066 // Enable discovery in the STW reference processor
4067 ref_processor_stw()->enable_discovery();
4068
4069 {
4070 // We want to temporarily turn off discovery by the
4071 // CM ref processor, if necessary, and turn it back on
4072 // on again later if we do. Using a scoped
4073 // NoRefDiscovery object will do this.
4074 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4075
4076 // Forget the current alloc region (we might even choose it to be part
4077 // of the collection set!).
4078 _allocator->release_mutator_alloc_region();
4079
4080 // We should call this after we retire the mutator alloc
4081 // region(s) so that all the ALLOC / RETIRE events are generated
4082 // before the start GC event.
4083 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4084
4085 // This timing is only used by the ergonomics to handle our pause target.
4086 // It is unclear why this should not include the full pause. We will
4087 // investigate this in CR 7178365.
4088 //
4089 // Preserving the old comment here if that helps the investigation:
4090 //
4091 // The elapsed time induced by the start time below deliberately elides
4092 // the possible verification above.
4093 double sample_start_time_sec = os::elapsedTime();
4094
4095 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4096
4097 if (collector_state()->during_initial_mark_pause()) {
4098 concurrent_mark()->checkpointRootsInitialPre();
4099 }
4100
4101 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
4102 g1_policy()->finalize_old_cset_part(time_remaining_ms);
4103
4104 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4105
4106 register_humongous_regions_with_cset();
4107
4108 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4109
4110 _cm->note_start_of_gc();
4111 // We call this after finalize_cset() to
4112 // ensure that the CSet has been finalized.
4113 _cm->verify_no_cset_oops();
4114
4115 if (_hr_printer.is_active()) {
4116 HeapRegion* hr = g1_policy()->collection_set();
4117 while (hr != NULL) {
4118 _hr_printer.cset(hr);
4119 hr = hr->next_in_collection_set();
4120 }
4121 }
4122
4123 #ifdef ASSERT
4124 VerifyCSetClosure cl;
4125 collection_set_iterate(&cl);
4126 #endif // ASSERT
4127
4128 // Initialize the GC alloc regions.
4129 _allocator->init_gc_alloc_regions(evacuation_info);
4130
4131 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
4132 // Actually do the work...
4133 evacuate_collection_set(evacuation_info, &per_thread_states);
4134
4135 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
4136 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
4137
4138 eagerly_reclaim_humongous_regions();
4139
4140 g1_policy()->clear_collection_set();
4141
4142 // Start a new incremental collection set for the next pause.
4143 g1_policy()->start_incremental_cset_building();
4144
4145 clear_cset_fast_test();
4146
4147 _young_list->reset_sampled_info();
4148
4149 // Don't check the whole heap at this point as the
4150 // GC alloc regions from this pause have been tagged
4151 // as survivors and moved on to the survivor list.
4152 // Survivor regions will fail the !is_young() check.
4153 assert(check_young_list_empty(false /* check_heap */),
4154 "young list should be empty");
4155
4156 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4157 _young_list->first_survivor_region(),
4158 _young_list->last_survivor_region());
4159
4160 _young_list->reset_auxilary_lists();
4161
4162 if (evacuation_failed()) {
4163 set_used(recalculate_used());
4164 if (_archive_allocator != NULL) {
4165 _archive_allocator->clear_used();
4166 }
4167 for (uint i = 0; i < ParallelGCThreads; i++) {
4168 if (_evacuation_failed_info_array[i].has_failed()) {
4169 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4170 }
4171 }
4172 } else {
4173 // The "used" of the the collection set have already been subtracted
4174 // when they were freed. Add in the bytes evacuated.
4175 increase_used(g1_policy()->bytes_copied_during_gc());
4176 }
4177
4178 if (collector_state()->during_initial_mark_pause()) {
4179 // We have to do this before we notify the CM threads that
4180 // they can start working to make sure that all the
4181 // appropriate initialization is done on the CM object.
4182 concurrent_mark()->checkpointRootsInitialPost();
4183 collector_state()->set_mark_in_progress(true);
4184 // Note that we don't actually trigger the CM thread at
4185 // this point. We do that later when we're sure that
4186 // the current thread has completed its logging output.
4187 }
4188
4189 allocate_dummy_regions();
4190
4191 _allocator->init_mutator_alloc_region();
4192
4193 {
4194 size_t expand_bytes = g1_policy()->expansion_amount();
4195 if (expand_bytes > 0) {
4196 size_t bytes_before = capacity();
4197 // No need for an ergo verbose message here,
4198 // expansion_amount() does this when it returns a value > 0.
4199 if (!expand(expand_bytes)) {
4200 // We failed to expand the heap. Cannot do anything about it.
4201 }
4202 }
4203 }
4204
4205 // We redo the verification but now wrt to the new CSet which
4206 // has just got initialized after the previous CSet was freed.
4207 _cm->verify_no_cset_oops();
4208 _cm->note_end_of_gc();
4209
4210 // This timing is only used by the ergonomics to handle our pause target.
4211 // It is unclear why this should not include the full pause. We will
4212 // investigate this in CR 7178365.
4213 double sample_end_time_sec = os::elapsedTime();
4214 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4215 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4216 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4217
4218 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4219 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4220
4221 MemoryService::track_memory_usage();
4222
4223 // In prepare_for_verify() below we'll need to scan the deferred
4224 // update buffers to bring the RSets up-to-date if
4225 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4226 // the update buffers we'll probably need to scan cards on the
4227 // regions we just allocated to (i.e., the GC alloc
4228 // regions). However, during the last GC we called
4229 // set_saved_mark() on all the GC alloc regions, so card
4230 // scanning might skip the [saved_mark_word()...top()] area of
4231 // those regions (i.e., the area we allocated objects into
4232 // during the last GC). But it shouldn't. Given that
4233 // saved_mark_word() is conditional on whether the GC time stamp
4234 // on the region is current or not, by incrementing the GC time
4235 // stamp here we invalidate all the GC time stamps on all the
4236 // regions and saved_mark_word() will simply return top() for
4237 // all the regions. This is a nicer way of ensuring this rather
4238 // than iterating over the regions and fixing them. In fact, the
4239 // GC time stamp increment here also ensures that
4240 // saved_mark_word() will return top() between pauses, i.e.,
4241 // during concurrent refinement. So we don't need the
4242 // is_gc_active() check to decided which top to use when
4243 // scanning cards (see CR 7039627).
4244 increment_gc_time_stamp();
4245
4246 verify_after_gc();
4247 check_bitmaps("GC End");
4248
4249 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4250 ref_processor_stw()->verify_no_references_recorded();
4251
4252 // CM reference discovery will be re-enabled if necessary.
4253 }
4254
4255 // We should do this after we potentially expand the heap so
4256 // that all the COMMIT events are generated before the end GC
4257 // event, and after we retire the GC alloc regions so that all
4258 // RETIRE events are generated before the end GC event.
4259 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4260
4261 #ifdef TRACESPINNING
4262 ParallelTaskTerminator::print_termination_counts();
4263 #endif
4264
4265 gc_epilogue(false);
4266 }
4267
4268 // Print the remainder of the GC log output.
4269 log_gc_footer(os::elapsedTime() - pause_start_sec);
4270
4271 // It is not yet to safe to tell the concurrent mark to
4272 // start as we have some optional output below. We don't want the
4273 // output from the concurrent mark thread interfering with this
4274 // logging output either.
4275
4276 _hrm.verify_optional();
4277 verify_region_sets_optional();
4278
4279 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4280 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4281
4282 print_heap_after_gc();
4283 trace_heap_after_gc(_gc_tracer_stw);
4284
4285 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4286 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4287 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4288 // before any GC notifications are raised.
4289 g1mm()->update_sizes();
4290
4291 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4292 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4293 _gc_timer_stw->register_gc_end();
4294 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4295 }
4296 // It should now be safe to tell the concurrent mark thread to start
4297 // without its logging output interfering with the logging output
4298 // that came from the pause.
4299
4300 if (should_start_conc_mark) {
4301 // CAUTION: after the doConcurrentMark() call below,
4302 // the concurrent marking thread(s) could be running
4303 // concurrently with us. Make sure that anything after
4304 // this point does not assume that we are the only GC thread
4305 // running. Note: of course, the actual marking work will
4306 // not start until the safepoint itself is released in
4307 // SuspendibleThreadSet::desynchronize().
4308 doConcurrentMark();
4309 }
4310
4311 return true;
4312 }
4313
4314 void G1CollectedHeap::remove_self_forwarding_pointers() {
4315 double remove_self_forwards_start = os::elapsedTime();
4316
4317 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4318 workers()->run_task(&rsfp_task);
4319
4320 // Now restore saved marks, if any.
4321 for (uint i = 0; i < ParallelGCThreads; i++) {
4322 OopAndMarkOopStack& cur = _preserved_objs[i];
4323 while (!cur.is_empty()) {
4324 OopAndMarkOop elem = cur.pop();
4325 elem.set_mark();
4326 }
4327 cur.clear(true);
4328 }
4329
4330 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4331 }
4332
4333 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4334 if (!_evacuation_failed) {
4335 _evacuation_failed = true;
4336 }
4337
4338 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4339
4340 // We want to call the "for_promotion_failure" version only in the
4341 // case of a promotion failure.
4342 if (m->must_be_preserved_for_promotion_failure(obj)) {
4343 OopAndMarkOop elem(obj, m);
4344 _preserved_objs[worker_id].push(elem);
4345 }
4346 }
4347
4348 class G1ParEvacuateFollowersClosure : public VoidClosure {
4349 private:
4350 double _start_term;
4351 double _term_time;
4352 size_t _term_attempts;
4353
4354 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4355 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4356 protected:
4357 G1CollectedHeap* _g1h;
4358 G1ParScanThreadState* _par_scan_state;
4359 RefToScanQueueSet* _queues;
4360 ParallelTaskTerminator* _terminator;
4361
4362 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4363 RefToScanQueueSet* queues() { return _queues; }
4364 ParallelTaskTerminator* terminator() { return _terminator; }
4365
4366 public:
4367 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4368 G1ParScanThreadState* par_scan_state,
4369 RefToScanQueueSet* queues,
4370 ParallelTaskTerminator* terminator)
4371 : _g1h(g1h), _par_scan_state(par_scan_state),
4372 _queues(queues), _terminator(terminator),
4373 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4374
4375 void do_void();
4376
4377 double term_time() const { return _term_time; }
4378 size_t term_attempts() const { return _term_attempts; }
4379
4380 private:
4381 inline bool offer_termination();
4382 };
4383
4384 bool G1ParEvacuateFollowersClosure::offer_termination() {
4385 G1ParScanThreadState* const pss = par_scan_state();
4386 start_term_time();
4387 const bool res = terminator()->offer_termination();
4388 end_term_time();
4389 return res;
4390 }
4391
4392 void G1ParEvacuateFollowersClosure::do_void() {
4393 G1ParScanThreadState* const pss = par_scan_state();
4394 pss->trim_queue();
4395 do {
4396 pss->steal_and_trim_queue(queues());
4397 } while (!offer_termination());
4398 }
4399
4400 class G1ParTask : public AbstractGangTask {
4401 protected:
4402 G1CollectedHeap* _g1h;
4403 G1ParScanThreadStateSet* _pss;
4404 RefToScanQueueSet* _queues;
4405 G1RootProcessor* _root_processor;
4406 ParallelTaskTerminator _terminator;
4407 uint _n_workers;
4408
4409 public:
4410 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4411 : AbstractGangTask("G1 collection"),
4412 _g1h(g1h),
4413 _pss(per_thread_states),
4414 _queues(task_queues),
4415 _root_processor(root_processor),
4416 _terminator(n_workers, _queues),
4417 _n_workers(n_workers)
4418 {}
4419
4420 void work(uint worker_id) {
4421 if (worker_id >= _n_workers) return; // no work needed this round
4422
4423 double start_sec = os::elapsedTime();
4424 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4425
4426 {
4427 ResourceMark rm;
4428 HandleMark hm;
4429
4430 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4431
4432 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4433 pss->set_ref_processor(rp);
4434
4435 double start_strong_roots_sec = os::elapsedTime();
4436
4437 _root_processor->evacuate_roots(pss->closures(), worker_id);
4438
4439 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(pss->closures(), worker_id);
4440
4441 _pss->add_cards_scanned(worker_id, cards_scanned);
4442
4443 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4444
4445 double term_sec = 0.0;
4446 size_t evac_term_attempts = 0;
4447 {
4448 double start = os::elapsedTime();
4449 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4450 evac.do_void();
4451
4452 evac_term_attempts = evac.term_attempts();
4453 term_sec = evac.term_time();
4454 double elapsed_sec = os::elapsedTime() - start;
4455 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4456 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4457 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4458 }
4459
4460 assert(pss->queue_is_empty(), "should be empty");
4461
4462 if (PrintTerminationStats) {
4463 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4464 size_t lab_waste;
4465 size_t lab_undo_waste;
4466 pss->waste(lab_waste, lab_undo_waste);
4467 _g1h->print_termination_stats(gclog_or_tty,
4468 worker_id,
4469 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4470 strong_roots_sec * 1000.0, /* strong roots time */
4471 term_sec * 1000.0, /* evac term time */
4472 evac_term_attempts, /* evac term attempts */
4473 lab_waste, /* alloc buffer waste */
4474 lab_undo_waste /* undo waste */
4475 );
4476 }
4477
4478 // Close the inner scope so that the ResourceMark and HandleMark
4479 // destructors are executed here and are included as part of the
4480 // "GC Worker Time".
4481 }
4482 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4483 }
4484 };
4485
4486 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4487 st->print_raw_cr("GC Termination Stats");
4488 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4489 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4490 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4491 }
4492
4493 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4494 uint worker_id,
4495 double elapsed_ms,
4496 double strong_roots_ms,
4497 double term_ms,
4498 size_t term_attempts,
4499 size_t alloc_buffer_waste,
4500 size_t undo_waste) const {
4501 st->print_cr("%3d %9.2f %9.2f %6.2f "
4502 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4503 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4504 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4505 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4506 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4507 alloc_buffer_waste * HeapWordSize / K,
4508 undo_waste * HeapWordSize / K);
4509 }
4510
4511 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4512 private:
4513 BoolObjectClosure* _is_alive;
4514 int _initial_string_table_size;
4515 int _initial_symbol_table_size;
4516
4517 bool _process_strings;
4518 int _strings_processed;
4519 int _strings_removed;
4520
4521 bool _process_symbols;
4522 int _symbols_processed;
4523 int _symbols_removed;
4524
4525 public:
4526 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4527 AbstractGangTask("String/Symbol Unlinking"),
4528 _is_alive(is_alive),
4529 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4530 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4531
4532 _initial_string_table_size = StringTable::the_table()->table_size();
4533 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4534 if (process_strings) {
4535 StringTable::clear_parallel_claimed_index();
4536 }
4537 if (process_symbols) {
4538 SymbolTable::clear_parallel_claimed_index();
4539 }
4540 }
4541
4542 ~G1StringSymbolTableUnlinkTask() {
4543 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4544 "claim value %d after unlink less than initial string table size %d",
4545 StringTable::parallel_claimed_index(), _initial_string_table_size);
4546 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4547 "claim value %d after unlink less than initial symbol table size %d",
4548 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4549
4550 if (G1TraceStringSymbolTableScrubbing) {
4551 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4552 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4553 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4554 strings_processed(), strings_removed(),
4555 symbols_processed(), symbols_removed());
4556 }
4557 }
4558
4559 void work(uint worker_id) {
4560 int strings_processed = 0;
4561 int strings_removed = 0;
4562 int symbols_processed = 0;
4563 int symbols_removed = 0;
4564 if (_process_strings) {
4565 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4566 Atomic::add(strings_processed, &_strings_processed);
4567 Atomic::add(strings_removed, &_strings_removed);
4568 }
4569 if (_process_symbols) {
4570 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4571 Atomic::add(symbols_processed, &_symbols_processed);
4572 Atomic::add(symbols_removed, &_symbols_removed);
4573 }
4574 }
4575
4576 size_t strings_processed() const { return (size_t)_strings_processed; }
4577 size_t strings_removed() const { return (size_t)_strings_removed; }
4578
4579 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4580 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4581 };
4582
4583 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4584 private:
4585 static Monitor* _lock;
4586
4587 BoolObjectClosure* const _is_alive;
4588 const bool _unloading_occurred;
4589 const uint _num_workers;
4590
4591 // Variables used to claim nmethods.
4592 nmethod* _first_nmethod;
4593 volatile nmethod* _claimed_nmethod;
4594
4595 // The list of nmethods that need to be processed by the second pass.
4596 volatile nmethod* _postponed_list;
4597 volatile uint _num_entered_barrier;
4598
4599 public:
4600 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4601 _is_alive(is_alive),
4602 _unloading_occurred(unloading_occurred),
4603 _num_workers(num_workers),
4604 _first_nmethod(NULL),
4605 _claimed_nmethod(NULL),
4606 _postponed_list(NULL),
4607 _num_entered_barrier(0)
4608 {
4609 nmethod::increase_unloading_clock();
4610 // Get first alive nmethod
4611 NMethodIterator iter = NMethodIterator();
4612 if(iter.next_alive()) {
4613 _first_nmethod = iter.method();
4614 }
4615 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4616 }
4617
4618 ~G1CodeCacheUnloadingTask() {
4619 CodeCache::verify_clean_inline_caches();
4620
4621 CodeCache::set_needs_cache_clean(false);
4622 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4623
4624 CodeCache::verify_icholder_relocations();
4625 }
4626
4627 private:
4628 void add_to_postponed_list(nmethod* nm) {
4629 nmethod* old;
4630 do {
4631 old = (nmethod*)_postponed_list;
4632 nm->set_unloading_next(old);
4633 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4634 }
4635
4636 void clean_nmethod(nmethod* nm) {
4637 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4638
4639 if (postponed) {
4640 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4641 add_to_postponed_list(nm);
4642 }
4643
4644 // Mark that this thread has been cleaned/unloaded.
4645 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4646 nm->set_unloading_clock(nmethod::global_unloading_clock());
4647 }
4648
4649 void clean_nmethod_postponed(nmethod* nm) {
4650 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4651 }
4652
4653 static const int MaxClaimNmethods = 16;
4654
4655 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4656 nmethod* first;
4657 NMethodIterator last;
4658
4659 do {
4660 *num_claimed_nmethods = 0;
4661
4662 first = (nmethod*)_claimed_nmethod;
4663 last = NMethodIterator(first);
4664
4665 if (first != NULL) {
4666
4667 for (int i = 0; i < MaxClaimNmethods; i++) {
4668 if (!last.next_alive()) {
4669 break;
4670 }
4671 claimed_nmethods[i] = last.method();
4672 (*num_claimed_nmethods)++;
4673 }
4674 }
4675
4676 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4677 }
4678
4679 nmethod* claim_postponed_nmethod() {
4680 nmethod* claim;
4681 nmethod* next;
4682
4683 do {
4684 claim = (nmethod*)_postponed_list;
4685 if (claim == NULL) {
4686 return NULL;
4687 }
4688
4689 next = claim->unloading_next();
4690
4691 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4692
4693 return claim;
4694 }
4695
4696 public:
4697 // Mark that we're done with the first pass of nmethod cleaning.
4698 void barrier_mark(uint worker_id) {
4699 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4700 _num_entered_barrier++;
4701 if (_num_entered_barrier == _num_workers) {
4702 ml.notify_all();
4703 }
4704 }
4705
4706 // See if we have to wait for the other workers to
4707 // finish their first-pass nmethod cleaning work.
4708 void barrier_wait(uint worker_id) {
4709 if (_num_entered_barrier < _num_workers) {
4710 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4711 while (_num_entered_barrier < _num_workers) {
4712 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4713 }
4714 }
4715 }
4716
4717 // Cleaning and unloading of nmethods. Some work has to be postponed
4718 // to the second pass, when we know which nmethods survive.
4719 void work_first_pass(uint worker_id) {
4720 // The first nmethods is claimed by the first worker.
4721 if (worker_id == 0 && _first_nmethod != NULL) {
4722 clean_nmethod(_first_nmethod);
4723 _first_nmethod = NULL;
4724 }
4725
4726 int num_claimed_nmethods;
4727 nmethod* claimed_nmethods[MaxClaimNmethods];
4728
4729 while (true) {
4730 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4731
4732 if (num_claimed_nmethods == 0) {
4733 break;
4734 }
4735
4736 for (int i = 0; i < num_claimed_nmethods; i++) {
4737 clean_nmethod(claimed_nmethods[i]);
4738 }
4739 }
4740 }
4741
4742 void work_second_pass(uint worker_id) {
4743 nmethod* nm;
4744 // Take care of postponed nmethods.
4745 while ((nm = claim_postponed_nmethod()) != NULL) {
4746 clean_nmethod_postponed(nm);
4747 }
4748 }
4749 };
4750
4751 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4752
4753 class G1KlassCleaningTask : public StackObj {
4754 BoolObjectClosure* _is_alive;
4755 volatile jint _clean_klass_tree_claimed;
4756 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4757
4758 public:
4759 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4760 _is_alive(is_alive),
4761 _clean_klass_tree_claimed(0),
4762 _klass_iterator() {
4763 }
4764
4765 private:
4766 bool claim_clean_klass_tree_task() {
4767 if (_clean_klass_tree_claimed) {
4768 return false;
4769 }
4770
4771 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4772 }
4773
4774 InstanceKlass* claim_next_klass() {
4775 Klass* klass;
4776 do {
4777 klass =_klass_iterator.next_klass();
4778 } while (klass != NULL && !klass->oop_is_instance());
4779
4780 return (InstanceKlass*)klass;
4781 }
4782
4783 public:
4784
4785 void clean_klass(InstanceKlass* ik) {
4786 ik->clean_implementors_list(_is_alive);
4787 ik->clean_method_data(_is_alive);
4788
4789 // G1 specific cleanup work that has
4790 // been moved here to be done in parallel.
4791 ik->clean_dependent_nmethods();
4792 }
4793
4794 void work() {
4795 ResourceMark rm;
4796
4797 // One worker will clean the subklass/sibling klass tree.
4798 if (claim_clean_klass_tree_task()) {
4799 Klass::clean_subklass_tree(_is_alive);
4800 }
4801
4802 // All workers will help cleaning the classes,
4803 InstanceKlass* klass;
4804 while ((klass = claim_next_klass()) != NULL) {
4805 clean_klass(klass);
4806 }
4807 }
4808 };
4809
4810 // To minimize the remark pause times, the tasks below are done in parallel.
4811 class G1ParallelCleaningTask : public AbstractGangTask {
4812 private:
4813 G1StringSymbolTableUnlinkTask _string_symbol_task;
4814 G1CodeCacheUnloadingTask _code_cache_task;
4815 G1KlassCleaningTask _klass_cleaning_task;
4816
4817 public:
4818 // The constructor is run in the VMThread.
4819 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4820 AbstractGangTask("Parallel Cleaning"),
4821 _string_symbol_task(is_alive, process_strings, process_symbols),
4822 _code_cache_task(num_workers, is_alive, unloading_occurred),
4823 _klass_cleaning_task(is_alive) {
4824 }
4825
4826 // The parallel work done by all worker threads.
4827 void work(uint worker_id) {
4828 // Do first pass of code cache cleaning.
4829 _code_cache_task.work_first_pass(worker_id);
4830
4831 // Let the threads mark that the first pass is done.
4832 _code_cache_task.barrier_mark(worker_id);
4833
4834 // Clean the Strings and Symbols.
4835 _string_symbol_task.work(worker_id);
4836
4837 // Wait for all workers to finish the first code cache cleaning pass.
4838 _code_cache_task.barrier_wait(worker_id);
4839
4840 // Do the second code cache cleaning work, which realize on
4841 // the liveness information gathered during the first pass.
4842 _code_cache_task.work_second_pass(worker_id);
4843
4844 // Clean all klasses that were not unloaded.
4845 _klass_cleaning_task.work();
4846 }
4847 };
4848
4849
4850 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4851 bool process_strings,
4852 bool process_symbols,
4853 bool class_unloading_occurred) {
4854 uint n_workers = workers()->active_workers();
4855
4856 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4857 n_workers, class_unloading_occurred);
4858 workers()->run_task(&g1_unlink_task);
4859 }
4860
4861 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4862 bool process_strings, bool process_symbols) {
4863 {
4864 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4865 workers()->run_task(&g1_unlink_task);
4866 }
4867
4868 if (G1StringDedup::is_enabled()) {
4869 G1StringDedup::unlink(is_alive);
4870 }
4871 }
4872
4873 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4874 private:
4875 DirtyCardQueueSet* _queue;
4876 public:
4877 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4878
4879 virtual void work(uint worker_id) {
4880 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4881 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4882
4883 RedirtyLoggedCardTableEntryClosure cl;
4884 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4885
4886 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4887 }
4888 };
4889
4890 void G1CollectedHeap::redirty_logged_cards() {
4891 double redirty_logged_cards_start = os::elapsedTime();
4892
4893 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4894 dirty_card_queue_set().reset_for_par_iteration();
4895 workers()->run_task(&redirty_task);
4896
4897 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4898 dcq.merge_bufferlists(&dirty_card_queue_set());
4899 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4900
4901 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4902 }
4903
4904 // Weak Reference Processing support
4905
4906 // An always "is_alive" closure that is used to preserve referents.
4907 // If the object is non-null then it's alive. Used in the preservation
4908 // of referent objects that are pointed to by reference objects
4909 // discovered by the CM ref processor.
4910 class G1AlwaysAliveClosure: public BoolObjectClosure {
4911 G1CollectedHeap* _g1;
4912 public:
4913 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4914 bool do_object_b(oop p) {
4915 if (p != NULL) {
4916 return true;
4917 }
4918 return false;
4919 }
4920 };
4921
4922 bool G1STWIsAliveClosure::do_object_b(oop p) {
4923 // An object is reachable if it is outside the collection set,
4924 // or is inside and copied.
4925 return !_g1->is_in_cset(p) || p->is_forwarded();
4926 }
4927
4928 // Non Copying Keep Alive closure
4929 class G1KeepAliveClosure: public OopClosure {
4930 G1CollectedHeap* _g1;
4931 public:
4932 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4933 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4934 void do_oop(oop* p) {
4935 oop obj = *p;
4936 assert(obj != NULL, "the caller should have filtered out NULL values");
4937
4938 const InCSetState cset_state = _g1->in_cset_state(obj);
4939 if (!cset_state.is_in_cset_or_humongous()) {
4940 return;
4941 }
4942 if (cset_state.is_in_cset()) {
4943 assert( obj->is_forwarded(), "invariant" );
4944 *p = obj->forwardee();
4945 } else {
4946 assert(!obj->is_forwarded(), "invariant" );
4947 assert(cset_state.is_humongous(),
4948 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4949 _g1->set_humongous_is_live(obj);
4950 }
4951 }
4952 };
4953
4954 // Copying Keep Alive closure - can be called from both
4955 // serial and parallel code as long as different worker
4956 // threads utilize different G1ParScanThreadState instances
4957 // and different queues.
4958
4959 class G1CopyingKeepAliveClosure: public OopClosure {
4960 G1CollectedHeap* _g1h;
4961 OopClosure* _copy_non_heap_obj_cl;
4962 G1ParScanThreadState* _par_scan_state;
4963
4964 public:
4965 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4966 OopClosure* non_heap_obj_cl,
4967 G1ParScanThreadState* pss):
4968 _g1h(g1h),
4969 _copy_non_heap_obj_cl(non_heap_obj_cl),
4970 _par_scan_state(pss)
4971 {}
4972
4973 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4974 virtual void do_oop( oop* p) { do_oop_work(p); }
4975
4976 template <class T> void do_oop_work(T* p) {
4977 oop obj = oopDesc::load_decode_heap_oop(p);
4978
4979 if (_g1h->is_in_cset_or_humongous(obj)) {
4980 // If the referent object has been forwarded (either copied
4981 // to a new location or to itself in the event of an
4982 // evacuation failure) then we need to update the reference
4983 // field and, if both reference and referent are in the G1
4984 // heap, update the RSet for the referent.
4985 //
4986 // If the referent has not been forwarded then we have to keep
4987 // it alive by policy. Therefore we have copy the referent.
4988 //
4989 // If the reference field is in the G1 heap then we can push
4990 // on the PSS queue. When the queue is drained (after each
4991 // phase of reference processing) the object and it's followers
4992 // will be copied, the reference field set to point to the
4993 // new location, and the RSet updated. Otherwise we need to
4994 // use the the non-heap or metadata closures directly to copy
4995 // the referent object and update the pointer, while avoiding
4996 // updating the RSet.
4997
4998 if (_g1h->is_in_g1_reserved(p)) {
4999 _par_scan_state->push_on_queue(p);
5000 } else {
5001 assert(!Metaspace::contains((const void*)p),
5002 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
5003 _copy_non_heap_obj_cl->do_oop(p);
5004 }
5005 }
5006 }
5007 };
5008
5009 // Serial drain queue closure. Called as the 'complete_gc'
5010 // closure for each discovered list in some of the
5011 // reference processing phases.
5012
5013 class G1STWDrainQueueClosure: public VoidClosure {
5014 protected:
5015 G1CollectedHeap* _g1h;
5016 G1ParScanThreadState* _par_scan_state;
5017
5018 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5019
5020 public:
5021 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5022 _g1h(g1h),
5023 _par_scan_state(pss)
5024 { }
5025
5026 void do_void() {
5027 G1ParScanThreadState* const pss = par_scan_state();
5028 pss->trim_queue();
5029 }
5030 };
5031
5032 // Parallel Reference Processing closures
5033
5034 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5035 // processing during G1 evacuation pauses.
5036
5037 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5038 private:
5039 G1CollectedHeap* _g1h;
5040 G1ParScanThreadStateSet* _pss;
5041 RefToScanQueueSet* _queues;
5042 WorkGang* _workers;
5043 uint _active_workers;
5044
5045 public:
5046 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5047 G1ParScanThreadStateSet* per_thread_states,
5048 WorkGang* workers,
5049 RefToScanQueueSet *task_queues,
5050 uint n_workers) :
5051 _g1h(g1h),
5052 _pss(per_thread_states),
5053 _queues(task_queues),
5054 _workers(workers),
5055 _active_workers(n_workers)
5056 {
5057 assert(n_workers > 0, "shouldn't call this otherwise");
5058 }
5059
5060 // Executes the given task using concurrent marking worker threads.
5061 virtual void execute(ProcessTask& task);
5062 virtual void execute(EnqueueTask& task);
5063 };
5064
5065 // Gang task for possibly parallel reference processing
5066
5067 class G1STWRefProcTaskProxy: public AbstractGangTask {
5068 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5069 ProcessTask& _proc_task;
5070 G1CollectedHeap* _g1h;
5071 G1ParScanThreadStateSet* _pss;
5072 RefToScanQueueSet* _task_queues;
5073 ParallelTaskTerminator* _terminator;
5074
5075 public:
5076 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5077 G1CollectedHeap* g1h,
5078 G1ParScanThreadStateSet* per_thread_states,
5079 RefToScanQueueSet *task_queues,
5080 ParallelTaskTerminator* terminator) :
5081 AbstractGangTask("Process reference objects in parallel"),
5082 _proc_task(proc_task),
5083 _g1h(g1h),
5084 _pss(per_thread_states),
5085 _task_queues(task_queues),
5086 _terminator(terminator)
5087 {}
5088
5089 virtual void work(uint worker_id) {
5090 // The reference processing task executed by a single worker.
5091 ResourceMark rm;
5092 HandleMark hm;
5093
5094 G1STWIsAliveClosure is_alive(_g1h);
5095
5096 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5097 pss->set_ref_processor(NULL);
5098
5099 // Keep alive closure.
5100 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
5101
5102 // Complete GC closure
5103 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5104
5105 // Call the reference processing task's work routine.
5106 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5107
5108 // Note we cannot assert that the refs array is empty here as not all
5109 // of the processing tasks (specifically phase2 - pp2_work) execute
5110 // the complete_gc closure (which ordinarily would drain the queue) so
5111 // the queue may not be empty.
5112 }
5113 };
5114
5115 // Driver routine for parallel reference processing.
5116 // Creates an instance of the ref processing gang
5117 // task and has the worker threads execute it.
5118 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5119 assert(_workers != NULL, "Need parallel worker threads.");
5120
5121 ParallelTaskTerminator terminator(_active_workers, _queues);
5122 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5123
5124 _workers->run_task(&proc_task_proxy);
5125 }
5126
5127 // Gang task for parallel reference enqueueing.
5128
5129 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5130 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5131 EnqueueTask& _enq_task;
5132
5133 public:
5134 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5135 AbstractGangTask("Enqueue reference objects in parallel"),
5136 _enq_task(enq_task)
5137 { }
5138
5139 virtual void work(uint worker_id) {
5140 _enq_task.work(worker_id);
5141 }
5142 };
5143
5144 // Driver routine for parallel reference enqueueing.
5145 // Creates an instance of the ref enqueueing gang
5146 // task and has the worker threads execute it.
5147
5148 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5149 assert(_workers != NULL, "Need parallel worker threads.");
5150
5151 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5152
5153 _workers->run_task(&enq_task_proxy);
5154 }
5155
5156 // End of weak reference support closures
5157
5158 // Abstract task used to preserve (i.e. copy) any referent objects
5159 // that are in the collection set and are pointed to by reference
5160 // objects discovered by the CM ref processor.
5161
5162 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5163 protected:
5164 G1CollectedHeap* _g1h;
5165 G1ParScanThreadStateSet* _pss;
5166 RefToScanQueueSet* _queues;
5167 ParallelTaskTerminator _terminator;
5168 uint _n_workers;
5169
5170 public:
5171 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5172 AbstractGangTask("ParPreserveCMReferents"),
5173 _g1h(g1h),
5174 _pss(per_thread_states),
5175 _queues(task_queues),
5176 _terminator(workers, _queues),
5177 _n_workers(workers)
5178 { }
5179
5180 void work(uint worker_id) {
5181 ResourceMark rm;
5182 HandleMark hm;
5183
5184 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5185 pss->set_ref_processor(NULL);
5186 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5187
5188 // Is alive closure
5189 G1AlwaysAliveClosure always_alive(_g1h);
5190
5191 // Copying keep alive closure. Applied to referent objects that need
5192 // to be copied.
5193 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
5194
5195 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5196
5197 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5198 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5199
5200 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5201 // So this must be true - but assert just in case someone decides to
5202 // change the worker ids.
5203 assert(worker_id < limit, "sanity");
5204 assert(!rp->discovery_is_atomic(), "check this code");
5205
5206 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5207 for (uint idx = worker_id; idx < limit; idx += stride) {
5208 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5209
5210 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5211 while (iter.has_next()) {
5212 // Since discovery is not atomic for the CM ref processor, we
5213 // can see some null referent objects.
5214 iter.load_ptrs(DEBUG_ONLY(true));
5215 oop ref = iter.obj();
5216
5217 // This will filter nulls.
5218 if (iter.is_referent_alive()) {
5219 iter.make_referent_alive();
5220 }
5221 iter.move_to_next();
5222 }
5223 }
5224
5225 // Drain the queue - which may cause stealing
5226 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5227 drain_queue.do_void();
5228 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5229 assert(pss->queue_is_empty(), "should be");
5230 }
5231 };
5232
5233 // Weak Reference processing during an evacuation pause (part 1).
5234 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5235 double ref_proc_start = os::elapsedTime();
5236
5237 ReferenceProcessor* rp = _ref_processor_stw;
5238 assert(rp->discovery_enabled(), "should have been enabled");
5239
5240 // Any reference objects, in the collection set, that were 'discovered'
5241 // by the CM ref processor should have already been copied (either by
5242 // applying the external root copy closure to the discovered lists, or
5243 // by following an RSet entry).
5244 //
5245 // But some of the referents, that are in the collection set, that these
5246 // reference objects point to may not have been copied: the STW ref
5247 // processor would have seen that the reference object had already
5248 // been 'discovered' and would have skipped discovering the reference,
5249 // but would not have treated the reference object as a regular oop.
5250 // As a result the copy closure would not have been applied to the
5251 // referent object.
5252 //
5253 // We need to explicitly copy these referent objects - the references
5254 // will be processed at the end of remarking.
5255 //
5256 // We also need to do this copying before we process the reference
5257 // objects discovered by the STW ref processor in case one of these
5258 // referents points to another object which is also referenced by an
5259 // object discovered by the STW ref processor.
5260
5261 uint no_of_gc_workers = workers()->active_workers();
5262
5263 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5264 per_thread_states,
5265 no_of_gc_workers,
5266 _task_queues);
5267
5268 workers()->run_task(&keep_cm_referents);
5269
5270 // Closure to test whether a referent is alive.
5271 G1STWIsAliveClosure is_alive(this);
5272
5273 // Even when parallel reference processing is enabled, the processing
5274 // of JNI refs is serial and performed serially by the current thread
5275 // rather than by a worker. The following PSS will be used for processing
5276 // JNI refs.
5277
5278 // Use only a single queue for this PSS.
5279 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5280 pss->set_ref_processor(NULL);
5281 assert(pss->queue_is_empty(), "pre-condition");
5282
5283 // Keep alive closure.
5284 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5285
5286 // Serial Complete GC closure
5287 G1STWDrainQueueClosure drain_queue(this, pss);
5288
5289 // Setup the soft refs policy...
5290 rp->setup_policy(false);
5291
5292 ReferenceProcessorStats stats;
5293 if (!rp->processing_is_mt()) {
5294 // Serial reference processing...
5295 stats = rp->process_discovered_references(&is_alive,
5296 &keep_alive,
5297 &drain_queue,
5298 NULL,
5299 _gc_timer_stw);
5300 } else {
5301 // Parallel reference processing
5302 assert(rp->num_q() == no_of_gc_workers, "sanity");
5303 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5304
5305 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5306 stats = rp->process_discovered_references(&is_alive,
5307 &keep_alive,
5308 &drain_queue,
5309 &par_task_executor,
5310 _gc_timer_stw);
5311 }
5312
5313 _gc_tracer_stw->report_gc_reference_stats(stats);
5314
5315 // We have completed copying any necessary live referent objects.
5316 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5317
5318 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5319 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5320 }
5321
5322 // Weak Reference processing during an evacuation pause (part 2).
5323 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5324 double ref_enq_start = os::elapsedTime();
5325
5326 ReferenceProcessor* rp = _ref_processor_stw;
5327 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5328
5329 // Now enqueue any remaining on the discovered lists on to
5330 // the pending list.
5331 if (!rp->processing_is_mt()) {
5332 // Serial reference processing...
5333 rp->enqueue_discovered_references();
5334 } else {
5335 // Parallel reference enqueueing
5336
5337 uint n_workers = workers()->active_workers();
5338
5339 assert(rp->num_q() == n_workers, "sanity");
5340 assert(n_workers <= rp->max_num_q(), "sanity");
5341
5342 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5343 rp->enqueue_discovered_references(&par_task_executor);
5344 }
5345
5346 rp->verify_no_references_recorded();
5347 assert(!rp->discovery_enabled(), "should have been disabled");
5348
5349 // FIXME
5350 // CM's reference processing also cleans up the string and symbol tables.
5351 // Should we do that here also? We could, but it is a serial operation
5352 // and could significantly increase the pause time.
5353
5354 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5355 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5356 }
5357
5358 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5359 _expand_heap_after_alloc_failure = true;
5360 _evacuation_failed = false;
5361
5362 // Should G1EvacuationFailureALot be in effect for this GC?
5363 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5364
5365 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5366
5367 // Disable the hot card cache.
5368 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5369 hot_card_cache->reset_hot_cache_claimed_index();
5370 hot_card_cache->set_use_cache(false);
5371
5372 const uint n_workers = workers()->active_workers();
5373
5374 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5375 double start_par_time_sec = os::elapsedTime();
5376 double end_par_time_sec;
5377
5378 {
5379 G1RootProcessor root_processor(this, n_workers);
5380 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5381 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5382 if (collector_state()->during_initial_mark_pause()) {
5383 ClassLoaderDataGraph::clear_claimed_marks();
5384 }
5385
5386 // The individual threads will set their evac-failure closures.
5387 if (PrintTerminationStats) {
5388 print_termination_stats_hdr(gclog_or_tty);
5389 }
5390
5391 workers()->run_task(&g1_par_task);
5392 end_par_time_sec = os::elapsedTime();
5393
5394 // Closing the inner scope will execute the destructor
5395 // for the G1RootProcessor object. We record the current
5396 // elapsed time before closing the scope so that time
5397 // taken for the destructor is NOT included in the
5398 // reported parallel time.
5399 }
5400
5401 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5402
5403 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5404 phase_times->record_par_time(par_time_ms);
5405
5406 double code_root_fixup_time_ms =
5407 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5408 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5409
5410 // Process any discovered reference objects - we have
5411 // to do this _before_ we retire the GC alloc regions
5412 // as we may have to copy some 'reachable' referent
5413 // objects (and their reachable sub-graphs) that were
5414 // not copied during the pause.
5415 process_discovered_references(per_thread_states);
5416
5417 if (G1StringDedup::is_enabled()) {
5418 double fixup_start = os::elapsedTime();
5419
5420 G1STWIsAliveClosure is_alive(this);
5421 G1KeepAliveClosure keep_alive(this);
5422 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5423
5424 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5425 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5426 }
5427
5428 _allocator->release_gc_alloc_regions(evacuation_info);
5429 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5430
5431 per_thread_states->flush();
5432
5433 record_obj_copy_mem_stats();
5434
5435 // Reset and re-enable the hot card cache.
5436 // Note the counts for the cards in the regions in the
5437 // collection set are reset when the collection set is freed.
5438 hot_card_cache->reset_hot_cache();
5439 hot_card_cache->set_use_cache(true);
5440
5441 purge_code_root_memory();
5442
5443 if (evacuation_failed()) {
5444 remove_self_forwarding_pointers();
5445
5446 // Reset the G1EvacuationFailureALot counters and flags
5447 // Note: the values are reset only when an actual
5448 // evacuation failure occurs.
5449 NOT_PRODUCT(reset_evacuation_should_fail();)
5450 }
5451
5452 // Enqueue any remaining references remaining on the STW
5453 // reference processor's discovered lists. We need to do
5454 // this after the card table is cleaned (and verified) as
5455 // the act of enqueueing entries on to the pending list
5456 // will log these updates (and dirty their associated
5457 // cards). We need these updates logged to update any
5458 // RSets.
5459 enqueue_discovered_references(per_thread_states);
5460
5461 redirty_logged_cards();
5462 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5463 }
5464
5465 void G1CollectedHeap::record_obj_copy_mem_stats() {
5466 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5467 create_g1_evac_summary(&_old_evac_stats));
5468 }
5469
5470 void G1CollectedHeap::free_region(HeapRegion* hr,
5471 FreeRegionList* free_list,
5472 bool par,
5473 bool locked) {
5474 assert(!hr->is_free(), "the region should not be free");
5475 assert(!hr->is_empty(), "the region should not be empty");
5476 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5477 assert(free_list != NULL, "pre-condition");
5478
5479 if (G1VerifyBitmaps) {
5480 MemRegion mr(hr->bottom(), hr->end());
5481 concurrent_mark()->clearRangePrevBitmap(mr);
5482 }
5483
5484 // Clear the card counts for this region.
5485 // Note: we only need to do this if the region is not young
5486 // (since we don't refine cards in young regions).
5487 if (!hr->is_young()) {
5488 _cg1r->hot_card_cache()->reset_card_counts(hr);
5489 }
5490 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5491 free_list->add_ordered(hr);
5492 }
5493
5494 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5495 FreeRegionList* free_list,
5496 bool par) {
5497 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5498 assert(free_list != NULL, "pre-condition");
5499
5500 size_t hr_capacity = hr->capacity();
5501 // We need to read this before we make the region non-humongous,
5502 // otherwise the information will be gone.
5503 uint last_index = hr->last_hc_index();
5504 hr->clear_humongous();
5505 free_region(hr, free_list, par);
5506
5507 uint i = hr->hrm_index() + 1;
5508 while (i < last_index) {
5509 HeapRegion* curr_hr = region_at(i);
5510 assert(curr_hr->is_continues_humongous(), "invariant");
5511 curr_hr->clear_humongous();
5512 free_region(curr_hr, free_list, par);
5513 i += 1;
5514 }
5515 }
5516
5517 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5518 const HeapRegionSetCount& humongous_regions_removed) {
5519 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5520 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5521 _old_set.bulk_remove(old_regions_removed);
5522 _humongous_set.bulk_remove(humongous_regions_removed);
5523 }
5524
5525 }
5526
5527 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5528 assert(list != NULL, "list can't be null");
5529 if (!list->is_empty()) {
5530 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5531 _hrm.insert_list_into_free_list(list);
5532 }
5533 }
5534
5535 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5536 decrease_used(bytes);
5537 }
5538
5539 class G1ParCleanupCTTask : public AbstractGangTask {
5540 G1SATBCardTableModRefBS* _ct_bs;
5541 G1CollectedHeap* _g1h;
5542 HeapRegion* volatile _su_head;
5543 public:
5544 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5545 G1CollectedHeap* g1h) :
5546 AbstractGangTask("G1 Par Cleanup CT Task"),
5547 _ct_bs(ct_bs), _g1h(g1h) { }
5548
5549 void work(uint worker_id) {
5550 HeapRegion* r;
5551 while (r = _g1h->pop_dirty_cards_region()) {
5552 clear_cards(r);
5553 }
5554 }
5555
5556 void clear_cards(HeapRegion* r) {
5557 // Cards of the survivors should have already been dirtied.
5558 if (!r->is_survivor()) {
5559 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5560 }
5561 }
5562 };
5563
5564 #ifndef PRODUCT
5565 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5566 G1CollectedHeap* _g1h;
5567 G1SATBCardTableModRefBS* _ct_bs;
5568 public:
5569 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5570 : _g1h(g1h), _ct_bs(ct_bs) { }
5571 virtual bool doHeapRegion(HeapRegion* r) {
5572 if (r->is_survivor()) {
5573 _g1h->verify_dirty_region(r);
5574 } else {
5575 _g1h->verify_not_dirty_region(r);
5576 }
5577 return false;
5578 }
5579 };
5580
5581 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5582 // All of the region should be clean.
5583 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5584 MemRegion mr(hr->bottom(), hr->end());
5585 ct_bs->verify_not_dirty_region(mr);
5586 }
5587
5588 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5589 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5590 // dirty allocated blocks as they allocate them. The thread that
5591 // retires each region and replaces it with a new one will do a
5592 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5593 // not dirty that area (one less thing to have to do while holding
5594 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5595 // is dirty.
5596 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5597 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5598 if (hr->is_young()) {
5599 ct_bs->verify_g1_young_region(mr);
5600 } else {
5601 ct_bs->verify_dirty_region(mr);
5602 }
5603 }
5604
5605 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5606 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5607 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5608 verify_dirty_region(hr);
5609 }
5610 }
5611
5612 void G1CollectedHeap::verify_dirty_young_regions() {
5613 verify_dirty_young_list(_young_list->first_region());
5614 }
5615
5616 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5617 HeapWord* tams, HeapWord* end) {
5618 guarantee(tams <= end,
5619 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5620 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5621 if (result < end) {
5622 gclog_or_tty->cr();
5623 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5624 bitmap_name, p2i(result));
5625 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5626 bitmap_name, p2i(tams), p2i(end));
5627 return false;
5628 }
5629 return true;
5630 }
5631
5632 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5633 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5634 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5635
5636 HeapWord* bottom = hr->bottom();
5637 HeapWord* ptams = hr->prev_top_at_mark_start();
5638 HeapWord* ntams = hr->next_top_at_mark_start();
5639 HeapWord* end = hr->end();
5640
5641 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5642
5643 bool res_n = true;
5644 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5645 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5646 // if we happen to be in that state.
5647 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5648 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5649 }
5650 if (!res_p || !res_n) {
5651 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5652 HR_FORMAT_PARAMS(hr));
5653 gclog_or_tty->print_cr("#### Caller: %s", caller);
5654 return false;
5655 }
5656 return true;
5657 }
5658
5659 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5660 if (!G1VerifyBitmaps) return;
5661
5662 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5663 }
5664
5665 class G1VerifyBitmapClosure : public HeapRegionClosure {
5666 private:
5667 const char* _caller;
5668 G1CollectedHeap* _g1h;
5669 bool _failures;
5670
5671 public:
5672 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5673 _caller(caller), _g1h(g1h), _failures(false) { }
5674
5675 bool failures() { return _failures; }
5676
5677 virtual bool doHeapRegion(HeapRegion* hr) {
5678 if (hr->is_continues_humongous()) return false;
5679
5680 bool result = _g1h->verify_bitmaps(_caller, hr);
5681 if (!result) {
5682 _failures = true;
5683 }
5684 return false;
5685 }
5686 };
5687
5688 void G1CollectedHeap::check_bitmaps(const char* caller) {
5689 if (!G1VerifyBitmaps) return;
5690
5691 G1VerifyBitmapClosure cl(caller, this);
5692 heap_region_iterate(&cl);
5693 guarantee(!cl.failures(), "bitmap verification");
5694 }
5695
5696 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5697 private:
5698 bool _failures;
5699 public:
5700 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5701
5702 virtual bool doHeapRegion(HeapRegion* hr) {
5703 uint i = hr->hrm_index();
5704 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5705 if (hr->is_humongous()) {
5706 if (hr->in_collection_set()) {
5707 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5708 _failures = true;
5709 return true;
5710 }
5711 if (cset_state.is_in_cset()) {
5712 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5713 _failures = true;
5714 return true;
5715 }
5716 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5717 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5718 _failures = true;
5719 return true;
5720 }
5721 } else {
5722 if (cset_state.is_humongous()) {
5723 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5724 _failures = true;
5725 return true;
5726 }
5727 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5728 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5729 hr->in_collection_set(), cset_state.value(), i);
5730 _failures = true;
5731 return true;
5732 }
5733 if (cset_state.is_in_cset()) {
5734 if (hr->is_young() != (cset_state.is_young())) {
5735 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5736 hr->is_young(), cset_state.value(), i);
5737 _failures = true;
5738 return true;
5739 }
5740 if (hr->is_old() != (cset_state.is_old())) {
5741 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5742 hr->is_old(), cset_state.value(), i);
5743 _failures = true;
5744 return true;
5745 }
5746 }
5747 }
5748 return false;
5749 }
5750
5751 bool failures() const { return _failures; }
5752 };
5753
5754 bool G1CollectedHeap::check_cset_fast_test() {
5755 G1CheckCSetFastTableClosure cl;
5756 _hrm.iterate(&cl);
5757 return !cl.failures();
5758 }
5759 #endif // PRODUCT
5760
5761 void G1CollectedHeap::cleanUpCardTable() {
5762 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5763 double start = os::elapsedTime();
5764
5765 {
5766 // Iterate over the dirty cards region list.
5767 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5768
5769 workers()->run_task(&cleanup_task);
5770 #ifndef PRODUCT
5771 if (G1VerifyCTCleanup || VerifyAfterGC) {
5772 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5773 heap_region_iterate(&cleanup_verifier);
5774 }
5775 #endif
5776 }
5777
5778 double elapsed = os::elapsedTime() - start;
5779 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5780 }
5781
5782 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5783 size_t pre_used = 0;
5784 FreeRegionList local_free_list("Local List for CSet Freeing");
5785
5786 double young_time_ms = 0.0;
5787 double non_young_time_ms = 0.0;
5788
5789 // Since the collection set is a superset of the the young list,
5790 // all we need to do to clear the young list is clear its
5791 // head and length, and unlink any young regions in the code below
5792 _young_list->clear();
5793
5794 G1CollectorPolicy* policy = g1_policy();
5795
5796 double start_sec = os::elapsedTime();
5797 bool non_young = true;
5798
5799 HeapRegion* cur = cs_head;
5800 int age_bound = -1;
5801 size_t rs_lengths = 0;
5802
5803 while (cur != NULL) {
5804 assert(!is_on_master_free_list(cur), "sanity");
5805 if (non_young) {
5806 if (cur->is_young()) {
5807 double end_sec = os::elapsedTime();
5808 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5809 non_young_time_ms += elapsed_ms;
5810
5811 start_sec = os::elapsedTime();
5812 non_young = false;
5813 }
5814 } else {
5815 if (!cur->is_young()) {
5816 double end_sec = os::elapsedTime();
5817 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5818 young_time_ms += elapsed_ms;
5819
5820 start_sec = os::elapsedTime();
5821 non_young = true;
5822 }
5823 }
5824
5825 rs_lengths += cur->rem_set()->occupied_locked();
5826
5827 HeapRegion* next = cur->next_in_collection_set();
5828 assert(cur->in_collection_set(), "bad CS");
5829 cur->set_next_in_collection_set(NULL);
5830 clear_in_cset(cur);
5831
5832 if (cur->is_young()) {
5833 int index = cur->young_index_in_cset();
5834 assert(index != -1, "invariant");
5835 assert((uint) index < policy->young_cset_region_length(), "invariant");
5836 size_t words_survived = surviving_young_words[index];
5837 cur->record_surv_words_in_group(words_survived);
5838
5839 // At this point the we have 'popped' cur from the collection set
5840 // (linked via next_in_collection_set()) but it is still in the
5841 // young list (linked via next_young_region()). Clear the
5842 // _next_young_region field.
5843 cur->set_next_young_region(NULL);
5844 } else {
5845 int index = cur->young_index_in_cset();
5846 assert(index == -1, "invariant");
5847 }
5848
5849 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5850 (!cur->is_young() && cur->young_index_in_cset() == -1),
5851 "invariant" );
5852
5853 if (!cur->evacuation_failed()) {
5854 MemRegion used_mr = cur->used_region();
5855
5856 // And the region is empty.
5857 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5858 pre_used += cur->used();
5859 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5860 } else {
5861 cur->uninstall_surv_rate_group();
5862 if (cur->is_young()) {
5863 cur->set_young_index_in_cset(-1);
5864 }
5865 cur->set_evacuation_failed(false);
5866 // The region is now considered to be old.
5867 cur->set_old();
5868 // Do some allocation statistics accounting. Regions that failed evacuation
5869 // are always made old, so there is no need to update anything in the young
5870 // gen statistics, but we need to update old gen statistics.
5871 size_t used_words = cur->marked_bytes() / HeapWordSize;
5872 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5873 _old_set.add(cur);
5874 evacuation_info.increment_collectionset_used_after(cur->used());
5875 }
5876 cur = next;
5877 }
5878
5879 evacuation_info.set_regions_freed(local_free_list.length());
5880 policy->record_max_rs_lengths(rs_lengths);
5881 policy->cset_regions_freed();
5882
5883 double end_sec = os::elapsedTime();
5884 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5885
5886 if (non_young) {
5887 non_young_time_ms += elapsed_ms;
5888 } else {
5889 young_time_ms += elapsed_ms;
5890 }
5891
5892 prepend_to_freelist(&local_free_list);
5893 decrement_summary_bytes(pre_used);
5894 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5895 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5896 }
5897
5898 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5899 private:
5900 FreeRegionList* _free_region_list;
5901 HeapRegionSet* _proxy_set;
5902 HeapRegionSetCount _humongous_regions_removed;
5903 size_t _freed_bytes;
5904 public:
5905
5906 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5907 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5908 }
5909
5910 virtual bool doHeapRegion(HeapRegion* r) {
5911 if (!r->is_starts_humongous()) {
5912 return false;
5913 }
5914
5915 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5916
5917 oop obj = (oop)r->bottom();
5918 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5919
5920 // The following checks whether the humongous object is live are sufficient.
5921 // The main additional check (in addition to having a reference from the roots
5922 // or the young gen) is whether the humongous object has a remembered set entry.
5923 //
5924 // A humongous object cannot be live if there is no remembered set for it
5925 // because:
5926 // - there can be no references from within humongous starts regions referencing
5927 // the object because we never allocate other objects into them.
5928 // (I.e. there are no intra-region references that may be missed by the
5929 // remembered set)
5930 // - as soon there is a remembered set entry to the humongous starts region
5931 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5932 // until the end of a concurrent mark.
5933 //
5934 // It is not required to check whether the object has been found dead by marking
5935 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5936 // all objects allocated during that time are considered live.
5937 // SATB marking is even more conservative than the remembered set.
5938 // So if at this point in the collection there is no remembered set entry,
5939 // nobody has a reference to it.
5940 // At the start of collection we flush all refinement logs, and remembered sets
5941 // are completely up-to-date wrt to references to the humongous object.
5942 //
5943 // Other implementation considerations:
5944 // - never consider object arrays at this time because they would pose
5945 // considerable effort for cleaning up the the remembered sets. This is
5946 // required because stale remembered sets might reference locations that
5947 // are currently allocated into.
5948 uint region_idx = r->hrm_index();
5949 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5950 !r->rem_set()->is_empty()) {
5951
5952 if (G1TraceEagerReclaimHumongousObjects) {
5953 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",
5954 region_idx,
5955 (size_t)obj->size() * HeapWordSize,
5956 p2i(r->bottom()),
5957 r->region_num(),
5958 r->rem_set()->occupied(),
5959 r->rem_set()->strong_code_roots_list_length(),
5960 next_bitmap->isMarked(r->bottom()),
5961 g1h->is_humongous_reclaim_candidate(region_idx),
5962 obj->is_typeArray()
5963 );
5964 }
5965
5966 return false;
5967 }
5968
5969 guarantee(obj->is_typeArray(),
5970 "Only eagerly reclaiming type arrays is supported, but the object "
5971 PTR_FORMAT " is not.", p2i(r->bottom()));
5972
5973 if (G1TraceEagerReclaimHumongousObjects) {
5974 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",
5975 region_idx,
5976 (size_t)obj->size() * HeapWordSize,
5977 p2i(r->bottom()),
5978 r->region_num(),
5979 r->rem_set()->occupied(),
5980 r->rem_set()->strong_code_roots_list_length(),
5981 next_bitmap->isMarked(r->bottom()),
5982 g1h->is_humongous_reclaim_candidate(region_idx),
5983 obj->is_typeArray()
5984 );
5985 }
5986 // Need to clear mark bit of the humongous object if already set.
5987 if (next_bitmap->isMarked(r->bottom())) {
5988 next_bitmap->clear(r->bottom());
5989 }
5990 _freed_bytes += r->used();
5991 r->set_containing_set(NULL);
5992 _humongous_regions_removed.increment(1u, r->capacity());
5993 g1h->free_humongous_region(r, _free_region_list, false);
5994
5995 return false;
5996 }
5997
5998 HeapRegionSetCount& humongous_free_count() {
5999 return _humongous_regions_removed;
6000 }
6001
6002 size_t bytes_freed() const {
6003 return _freed_bytes;
6004 }
6005
6006 size_t humongous_reclaimed() const {
6007 return _humongous_regions_removed.length();
6008 }
6009 };
6010
6011 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6012 assert_at_safepoint(true);
6013
6014 if (!G1EagerReclaimHumongousObjects ||
6015 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6016 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6017 return;
6018 }
6019
6020 double start_time = os::elapsedTime();
6021
6022 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6023
6024 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6025 heap_region_iterate(&cl);
6026
6027 HeapRegionSetCount empty_set;
6028 remove_from_old_sets(empty_set, cl.humongous_free_count());
6029
6030 G1HRPrinter* hrp = hr_printer();
6031 if (hrp->is_active()) {
6032 FreeRegionListIterator iter(&local_cleanup_list);
6033 while (iter.more_available()) {
6034 HeapRegion* hr = iter.get_next();
6035 hrp->cleanup(hr);
6036 }
6037 }
6038
6039 prepend_to_freelist(&local_cleanup_list);
6040 decrement_summary_bytes(cl.bytes_freed());
6041
6042 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6043 cl.humongous_reclaimed());
6044 }
6045
6046 // This routine is similar to the above but does not record
6047 // any policy statistics or update free lists; we are abandoning
6048 // the current incremental collection set in preparation of a
6049 // full collection. After the full GC we will start to build up
6050 // the incremental collection set again.
6051 // This is only called when we're doing a full collection
6052 // and is immediately followed by the tearing down of the young list.
6053
6054 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6055 HeapRegion* cur = cs_head;
6056
6057 while (cur != NULL) {
6058 HeapRegion* next = cur->next_in_collection_set();
6059 assert(cur->in_collection_set(), "bad CS");
6060 cur->set_next_in_collection_set(NULL);
6061 clear_in_cset(cur);
6062 cur->set_young_index_in_cset(-1);
6063 cur = next;
6064 }
6065 }
6066
6067 void G1CollectedHeap::set_free_regions_coming() {
6068 if (G1ConcRegionFreeingVerbose) {
6069 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6070 "setting free regions coming");
6071 }
6072
6073 assert(!free_regions_coming(), "pre-condition");
6074 _free_regions_coming = true;
6075 }
6076
6077 void G1CollectedHeap::reset_free_regions_coming() {
6078 assert(free_regions_coming(), "pre-condition");
6079
6080 {
6081 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6082 _free_regions_coming = false;
6083 SecondaryFreeList_lock->notify_all();
6084 }
6085
6086 if (G1ConcRegionFreeingVerbose) {
6087 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6088 "reset free regions coming");
6089 }
6090 }
6091
6092 void G1CollectedHeap::wait_while_free_regions_coming() {
6093 // Most of the time we won't have to wait, so let's do a quick test
6094 // first before we take the lock.
6095 if (!free_regions_coming()) {
6096 return;
6097 }
6098
6099 if (G1ConcRegionFreeingVerbose) {
6100 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6101 "waiting for free regions");
6102 }
6103
6104 {
6105 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6106 while (free_regions_coming()) {
6107 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6108 }
6109 }
6110
6111 if (G1ConcRegionFreeingVerbose) {
6112 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6113 "done waiting for free regions");
6114 }
6115 }
6116
6117 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6118 return _allocator->is_retained_old_region(hr);
6119 }
6120
6121 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6122 _young_list->push_region(hr);
6123 }
6124
6125 class NoYoungRegionsClosure: public HeapRegionClosure {
6126 private:
6127 bool _success;
6128 public:
6129 NoYoungRegionsClosure() : _success(true) { }
6130 bool doHeapRegion(HeapRegion* r) {
6131 if (r->is_young()) {
6132 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6133 p2i(r->bottom()), p2i(r->end()));
6134 _success = false;
6135 }
6136 return false;
6137 }
6138 bool success() { return _success; }
6139 };
6140
6141 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6142 bool ret = _young_list->check_list_empty(check_sample);
6143
6144 if (check_heap) {
6145 NoYoungRegionsClosure closure;
6146 heap_region_iterate(&closure);
6147 ret = ret && closure.success();
6148 }
6149
6150 return ret;
6151 }
6152
6153 class TearDownRegionSetsClosure : public HeapRegionClosure {
6154 private:
6155 HeapRegionSet *_old_set;
6156
6157 public:
6158 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6159
6160 bool doHeapRegion(HeapRegion* r) {
6161 if (r->is_old()) {
6162 _old_set->remove(r);
6163 } else {
6164 // We ignore free regions, we'll empty the free list afterwards.
6165 // We ignore young regions, we'll empty the young list afterwards.
6166 // We ignore humongous regions, we're not tearing down the
6167 // humongous regions set.
6168 assert(r->is_free() || r->is_young() || r->is_humongous(),
6169 "it cannot be another type");
6170 }
6171 return false;
6172 }
6173
6174 ~TearDownRegionSetsClosure() {
6175 assert(_old_set->is_empty(), "post-condition");
6176 }
6177 };
6178
6179 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6180 assert_at_safepoint(true /* should_be_vm_thread */);
6181
6182 if (!free_list_only) {
6183 TearDownRegionSetsClosure cl(&_old_set);
6184 heap_region_iterate(&cl);
6185
6186 // Note that emptying the _young_list is postponed and instead done as
6187 // the first step when rebuilding the regions sets again. The reason for
6188 // this is that during a full GC string deduplication needs to know if
6189 // a collected region was young or old when the full GC was initiated.
6190 }
6191 _hrm.remove_all_free_regions();
6192 }
6193
6194 void G1CollectedHeap::increase_used(size_t bytes) {
6195 _summary_bytes_used += bytes;
6196 }
6197
6198 void G1CollectedHeap::decrease_used(size_t bytes) {
6199 assert(_summary_bytes_used >= bytes,
6200 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6201 _summary_bytes_used, bytes);
6202 _summary_bytes_used -= bytes;
6203 }
6204
6205 void G1CollectedHeap::set_used(size_t bytes) {
6206 _summary_bytes_used = bytes;
6207 }
6208
6209 class RebuildRegionSetsClosure : public HeapRegionClosure {
6210 private:
6211 bool _free_list_only;
6212 HeapRegionSet* _old_set;
6213 HeapRegionManager* _hrm;
6214 size_t _total_used;
6215
6216 public:
6217 RebuildRegionSetsClosure(bool free_list_only,
6218 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6219 _free_list_only(free_list_only),
6220 _old_set(old_set), _hrm(hrm), _total_used(0) {
6221 assert(_hrm->num_free_regions() == 0, "pre-condition");
6222 if (!free_list_only) {
6223 assert(_old_set->is_empty(), "pre-condition");
6224 }
6225 }
6226
6227 bool doHeapRegion(HeapRegion* r) {
6228 if (r->is_continues_humongous()) {
6229 return false;
6230 }
6231
6232 if (r->is_empty()) {
6233 // Add free regions to the free list
6234 r->set_free();
6235 r->set_allocation_context(AllocationContext::system());
6236 _hrm->insert_into_free_list(r);
6237 } else if (!_free_list_only) {
6238 assert(!r->is_young(), "we should not come across young regions");
6239
6240 if (r->is_humongous()) {
6241 // We ignore humongous regions. We left the humongous set unchanged.
6242 } else {
6243 // Objects that were compacted would have ended up on regions
6244 // that were previously old or free. Archive regions (which are
6245 // old) will not have been touched.
6246 assert(r->is_free() || r->is_old(), "invariant");
6247 // We now consider them old, so register as such. Leave
6248 // archive regions set that way, however, while still adding
6249 // them to the old set.
6250 if (!r->is_archive()) {
6251 r->set_old();
6252 }
6253 _old_set->add(r);
6254 }
6255 _total_used += r->used();
6256 }
6257
6258 return false;
6259 }
6260
6261 size_t total_used() {
6262 return _total_used;
6263 }
6264 };
6265
6266 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6267 assert_at_safepoint(true /* should_be_vm_thread */);
6268
6269 if (!free_list_only) {
6270 _young_list->empty_list();
6271 }
6272
6273 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6274 heap_region_iterate(&cl);
6275
6276 if (!free_list_only) {
6277 set_used(cl.total_used());
6278 if (_archive_allocator != NULL) {
6279 _archive_allocator->clear_used();
6280 }
6281 }
6282 assert(used_unlocked() == recalculate_used(),
6283 "inconsistent used_unlocked(), "
6284 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6285 used_unlocked(), recalculate_used());
6286 }
6287
6288 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6289 _refine_cte_cl->set_concurrent(concurrent);
6290 }
6291
6292 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6293 HeapRegion* hr = heap_region_containing(p);
6294 return hr->is_in(p);
6295 }
6296
6297 // Methods for the mutator alloc region
6298
6299 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6300 bool force) {
6301 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6302 assert(!force || g1_policy()->can_expand_young_list(),
6303 "if force is true we should be able to expand the young list");
6304 bool young_list_full = g1_policy()->is_young_list_full();
6305 if (force || !young_list_full) {
6306 HeapRegion* new_alloc_region = new_region(word_size,
6307 false /* is_old */,
6308 false /* do_expand */);
6309 if (new_alloc_region != NULL) {
6310 set_region_short_lived_locked(new_alloc_region);
6311 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6312 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6313 return new_alloc_region;
6314 }
6315 }
6316 return NULL;
6317 }
6318
6319 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6320 size_t allocated_bytes) {
6321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6322 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6323
6324 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6325 increase_used(allocated_bytes);
6326 _hr_printer.retire(alloc_region);
6327 // We update the eden sizes here, when the region is retired,
6328 // instead of when it's allocated, since this is the point that its
6329 // used space has been recored in _summary_bytes_used.
6330 g1mm()->update_eden_size();
6331 }
6332
6333 // Methods for the GC alloc regions
6334
6335 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6336 uint count,
6337 InCSetState dest) {
6338 assert(FreeList_lock->owned_by_self(), "pre-condition");
6339
6340 if (count < g1_policy()->max_regions(dest)) {
6341 const bool is_survivor = (dest.is_young());
6342 HeapRegion* new_alloc_region = new_region(word_size,
6343 !is_survivor,
6344 true /* do_expand */);
6345 if (new_alloc_region != NULL) {
6346 // We really only need to do this for old regions given that we
6347 // should never scan survivors. But it doesn't hurt to do it
6348 // for survivors too.
6349 new_alloc_region->record_timestamp();
6350 if (is_survivor) {
6351 new_alloc_region->set_survivor();
6352 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6353 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6354 } else {
6355 new_alloc_region->set_old();
6356 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6357 check_bitmaps("Old Region Allocation", new_alloc_region);
6358 }
6359 bool during_im = collector_state()->during_initial_mark_pause();
6360 new_alloc_region->note_start_of_copying(during_im);
6361 return new_alloc_region;
6362 }
6363 }
6364 return NULL;
6365 }
6366
6367 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6368 size_t allocated_bytes,
6369 InCSetState dest) {
6370 bool during_im = collector_state()->during_initial_mark_pause();
6371 alloc_region->note_end_of_copying(during_im);
6372 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6373 if (dest.is_young()) {
6374 young_list()->add_survivor_region(alloc_region);
6375 } else {
6376 _old_set.add(alloc_region);
6377 }
6378 _hr_printer.retire(alloc_region);
6379 }
6380
6381 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6382 bool expanded = false;
6383 uint index = _hrm.find_highest_free(&expanded);
6384
6385 if (index != G1_NO_HRM_INDEX) {
6386 if (expanded) {
6387 ergo_verbose1(ErgoHeapSizing,
6388 "attempt heap expansion",
6389 ergo_format_reason("requested address range outside heap bounds")
6390 ergo_format_byte("region size"),
6391 HeapRegion::GrainWords * HeapWordSize);
6392 }
6393 _hrm.allocate_free_regions_starting_at(index, 1);
6394 return region_at(index);
6395 }
6396 return NULL;
6397 }
6398
6399 // Heap region set verification
6400
6401 class VerifyRegionListsClosure : public HeapRegionClosure {
6402 private:
6403 HeapRegionSet* _old_set;
6404 HeapRegionSet* _humongous_set;
6405 HeapRegionManager* _hrm;
6406
6407 public:
6408 HeapRegionSetCount _old_count;
6409 HeapRegionSetCount _humongous_count;
6410 HeapRegionSetCount _free_count;
6411
6412 VerifyRegionListsClosure(HeapRegionSet* old_set,
6413 HeapRegionSet* humongous_set,
6414 HeapRegionManager* hrm) :
6415 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6416 _old_count(), _humongous_count(), _free_count(){ }
6417
6418 bool doHeapRegion(HeapRegion* hr) {
6419 if (hr->is_continues_humongous()) {
6420 return false;
6421 }
6422
6423 if (hr->is_young()) {
6424 // TODO
6425 } else if (hr->is_starts_humongous()) {
6426 assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index());
6427 _humongous_count.increment(1u, hr->capacity());
6428 } else if (hr->is_empty()) {
6429 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6430 _free_count.increment(1u, hr->capacity());
6431 } else if (hr->is_old()) {
6432 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6433 _old_count.increment(1u, hr->capacity());
6434 } else {
6435 // There are no other valid region types. Check for one invalid
6436 // one we can identify: pinned without old or humongous set.
6437 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6438 ShouldNotReachHere();
6439 }
6440 return false;
6441 }
6442
6443 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6444 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6445 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6446 old_set->total_capacity_bytes(), _old_count.capacity());
6447
6448 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6449 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6450 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6451
6452 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());
6453 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6454 free_list->total_capacity_bytes(), _free_count.capacity());
6455 }
6456 };
6457
6458 void G1CollectedHeap::verify_region_sets() {
6459 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6460
6461 // First, check the explicit lists.
6462 _hrm.verify();
6463 {
6464 // Given that a concurrent operation might be adding regions to
6465 // the secondary free list we have to take the lock before
6466 // verifying it.
6467 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6468 _secondary_free_list.verify_list();
6469 }
6470
6471 // If a concurrent region freeing operation is in progress it will
6472 // be difficult to correctly attributed any free regions we come
6473 // across to the correct free list given that they might belong to
6474 // one of several (free_list, secondary_free_list, any local lists,
6475 // etc.). So, if that's the case we will skip the rest of the
6476 // verification operation. Alternatively, waiting for the concurrent
6477 // operation to complete will have a non-trivial effect on the GC's
6478 // operation (no concurrent operation will last longer than the
6479 // interval between two calls to verification) and it might hide
6480 // any issues that we would like to catch during testing.
6481 if (free_regions_coming()) {
6482 return;
6483 }
6484
6485 // Make sure we append the secondary_free_list on the free_list so
6486 // that all free regions we will come across can be safely
6487 // attributed to the free_list.
6488 append_secondary_free_list_if_not_empty_with_lock();
6489
6490 // Finally, make sure that the region accounting in the lists is
6491 // consistent with what we see in the heap.
6492
6493 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6494 heap_region_iterate(&cl);
6495 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6496 }
6497
6498 // Optimized nmethod scanning
6499
6500 class RegisterNMethodOopClosure: public OopClosure {
6501 G1CollectedHeap* _g1h;
6502 nmethod* _nm;
6503
6504 template <class T> void do_oop_work(T* p) {
6505 T heap_oop = oopDesc::load_heap_oop(p);
6506 if (!oopDesc::is_null(heap_oop)) {
6507 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6508 HeapRegion* hr = _g1h->heap_region_containing(obj);
6509 assert(!hr->is_continues_humongous(),
6510 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6511 " starting at " HR_FORMAT,
6512 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6513
6514 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6515 hr->add_strong_code_root_locked(_nm);
6516 }
6517 }
6518
6519 public:
6520 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6521 _g1h(g1h), _nm(nm) {}
6522
6523 void do_oop(oop* p) { do_oop_work(p); }
6524 void do_oop(narrowOop* p) { do_oop_work(p); }
6525 };
6526
6527 class UnregisterNMethodOopClosure: public OopClosure {
6528 G1CollectedHeap* _g1h;
6529 nmethod* _nm;
6530
6531 template <class T> void do_oop_work(T* p) {
6532 T heap_oop = oopDesc::load_heap_oop(p);
6533 if (!oopDesc::is_null(heap_oop)) {
6534 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6535 HeapRegion* hr = _g1h->heap_region_containing(obj);
6536 assert(!hr->is_continues_humongous(),
6537 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6538 " starting at " HR_FORMAT,
6539 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6540
6541 hr->remove_strong_code_root(_nm);
6542 }
6543 }
6544
6545 public:
6546 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6547 _g1h(g1h), _nm(nm) {}
6548
6549 void do_oop(oop* p) { do_oop_work(p); }
6550 void do_oop(narrowOop* p) { do_oop_work(p); }
6551 };
6552
6553 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6554 CollectedHeap::register_nmethod(nm);
6555
6556 guarantee(nm != NULL, "sanity");
6557 RegisterNMethodOopClosure reg_cl(this, nm);
6558 nm->oops_do(®_cl);
6559 }
6560
6561 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6562 CollectedHeap::unregister_nmethod(nm);
6563
6564 guarantee(nm != NULL, "sanity");
6565 UnregisterNMethodOopClosure reg_cl(this, nm);
6566 nm->oops_do(®_cl, true);
6567 }
6568
6569 void G1CollectedHeap::purge_code_root_memory() {
6570 double purge_start = os::elapsedTime();
6571 G1CodeRootSet::purge();
6572 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6573 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6574 }
6575
6576 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6577 G1CollectedHeap* _g1h;
6578
6579 public:
6580 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6581 _g1h(g1h) {}
6582
6583 void do_code_blob(CodeBlob* cb) {
6584 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6585 if (nm == NULL) {
6586 return;
6587 }
6588
6589 if (ScavengeRootsInCode) {
6590 _g1h->register_nmethod(nm);
6591 }
6592 }
6593 };
6594
6595 void G1CollectedHeap::rebuild_strong_code_roots() {
6596 RebuildStrongCodeRootClosure blob_cl(this);
6597 CodeCache::blobs_do(&blob_cl);
6598 }