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