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