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/g1AllocRegion.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/orderAccess.inline.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "utilities/globalDefinitions.hpp"
71 #include "utilities/stack.inline.hpp"
72
73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
74
75 // turn it on so that the contents of the young list (scan-only /
76 // to-be-collected) are printed at "strategic" points before / during
77 // / after the collection --- this is useful for debugging
78 #define YOUNG_LIST_VERBOSE 0
79 // CURRENT STATUS
80 // This file is under construction. Search for "FIXME".
81
82 // INVARIANTS/NOTES
83 //
84 // All allocation activity covered by the G1CollectedHeap interface is
85 // serialized by acquiring the HeapLock. This happens in mem_allocate
86 // and allocate_new_tlab, which are the "entry" points to the
87 // allocation code from the rest of the JVM. (Note that this does not
88 // apply to TLAB allocation, which is not part of this interface: it
89 // is done by clients of this interface.)
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 bool _concurrent;
95 public:
96 RefineCardTableEntryClosure() : _concurrent(true) { }
97
98 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
99 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
100 // This path is executed by the concurrent refine or mutator threads,
101 // concurrently, and so we do not care if card_ptr contains references
102 // that point into the collection set.
103 assert(!oops_into_cset, "should be");
104
105 if (_concurrent && SuspendibleThreadSet::should_yield()) {
106 // Caller will actually yield.
107 return false;
108 }
109 // Otherwise, we finished successfully; return true.
110 return true;
111 }
112
113 void set_concurrent(bool b) { _concurrent = b; }
114 };
115
116
117 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
118 private:
119 size_t _num_processed;
120
121 public:
122 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
123
124 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
125 *card_ptr = CardTableModRefBS::dirty_card_val();
126 _num_processed++;
127 return true;
128 }
129
130 size_t num_processed() const { return _num_processed; }
131 };
132
133 YoungList::YoungList(G1CollectedHeap* g1h) :
134 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
135 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
136 guarantee(check_list_empty(false), "just making sure...");
137 }
138
139 void YoungList::push_region(HeapRegion *hr) {
140 assert(!hr->is_young(), "should not already be young");
141 assert(hr->get_next_young_region() == NULL, "cause it should!");
142
143 hr->set_next_young_region(_head);
144 _head = hr;
145
146 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
147 ++_length;
148 }
149
150 void YoungList::add_survivor_region(HeapRegion* hr) {
151 assert(hr->is_survivor(), "should be flagged as survivor region");
152 assert(hr->get_next_young_region() == NULL, "cause it should!");
153
154 hr->set_next_young_region(_survivor_head);
155 if (_survivor_head == NULL) {
156 _survivor_tail = hr;
157 }
158 _survivor_head = hr;
159 ++_survivor_length;
160 }
161
162 void YoungList::empty_list(HeapRegion* list) {
163 while (list != NULL) {
164 HeapRegion* next = list->get_next_young_region();
165 list->set_next_young_region(NULL);
166 list->uninstall_surv_rate_group();
167 // This is called before a Full GC and all the non-empty /
168 // non-humongous regions at the end of the Full GC will end up as
169 // old anyway.
170 list->set_old();
171 list = next;
172 }
173 }
174
175 void YoungList::empty_list() {
176 assert(check_list_well_formed(), "young list should be well formed");
177
178 empty_list(_head);
179 _head = NULL;
180 _length = 0;
181
182 empty_list(_survivor_head);
183 _survivor_head = NULL;
184 _survivor_tail = NULL;
185 _survivor_length = 0;
186
187 _last_sampled_rs_lengths = 0;
188
189 assert(check_list_empty(false), "just making sure...");
190 }
191
192 bool YoungList::check_list_well_formed() {
193 bool ret = true;
194
195 uint length = 0;
196 HeapRegion* curr = _head;
197 HeapRegion* last = NULL;
198 while (curr != NULL) {
199 if (!curr->is_young()) {
200 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
201 "incorrectly tagged (y: %d, surv: %d)",
202 p2i(curr->bottom()), p2i(curr->end()),
203 curr->is_young(), curr->is_survivor());
204 ret = false;
205 }
206 ++length;
207 last = curr;
208 curr = curr->get_next_young_region();
209 }
210 ret = ret && (length == _length);
211
212 if (!ret) {
213 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
214 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
215 length, _length);
216 }
217
218 return ret;
219 }
220
221 bool YoungList::check_list_empty(bool check_sample) {
222 bool ret = true;
223
224 if (_length != 0) {
225 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
226 _length);
227 ret = false;
228 }
229 if (check_sample && _last_sampled_rs_lengths != 0) {
230 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
231 ret = false;
232 }
233 if (_head != NULL) {
234 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
235 ret = false;
236 }
237 if (!ret) {
238 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
239 }
240
241 return ret;
242 }
243
244 void
245 YoungList::rs_length_sampling_init() {
246 _sampled_rs_lengths = 0;
247 _curr = _head;
248 }
249
250 bool
251 YoungList::rs_length_sampling_more() {
252 return _curr != NULL;
253 }
254
255 void
256 YoungList::rs_length_sampling_next() {
257 assert( _curr != NULL, "invariant" );
258 size_t rs_length = _curr->rem_set()->occupied();
259
260 _sampled_rs_lengths += rs_length;
261
262 // The current region may not yet have been added to the
263 // incremental collection set (it gets added when it is
264 // retired as the current allocation region).
265 if (_curr->in_collection_set()) {
266 // Update the collection set policy information for this region
267 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
268 }
269
270 _curr = _curr->get_next_young_region();
271 if (_curr == NULL) {
272 _last_sampled_rs_lengths = _sampled_rs_lengths;
273 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
274 }
275 }
276
277 void
278 YoungList::reset_auxilary_lists() {
279 guarantee( is_empty(), "young list should be empty" );
280 assert(check_list_well_formed(), "young list should be well formed");
281
282 // Add survivor regions to SurvRateGroup.
283 _g1h->g1_policy()->note_start_adding_survivor_regions();
284 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
285
286 int young_index_in_cset = 0;
287 for (HeapRegion* curr = _survivor_head;
288 curr != NULL;
289 curr = curr->get_next_young_region()) {
290 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
291
292 // The region is a non-empty survivor so let's add it to
293 // the incremental collection set for the next evacuation
294 // pause.
295 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
296 young_index_in_cset += 1;
297 }
298 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
299 _g1h->g1_policy()->note_stop_adding_survivor_regions();
300
301 _head = _survivor_head;
302 _length = _survivor_length;
303 if (_survivor_head != NULL) {
304 assert(_survivor_tail != NULL, "cause it shouldn't be");
305 assert(_survivor_length > 0, "invariant");
306 _survivor_tail->set_next_young_region(NULL);
307 }
308
309 // Don't clear the survivor list handles until the start of
310 // the next evacuation pause - we need it in order to re-tag
311 // the survivor regions from this evacuation pause as 'young'
312 // at the start of the next.
313
314 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
315
316 assert(check_list_well_formed(), "young list should be well formed");
317 }
318
319 void YoungList::print() {
320 HeapRegion* lists[] = {_head, _survivor_head};
321 const char* names[] = {"YOUNG", "SURVIVOR"};
322
323 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
324 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
325 HeapRegion *curr = lists[list];
326 if (curr == NULL)
327 gclog_or_tty->print_cr(" empty");
328 while (curr != NULL) {
329 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
330 HR_FORMAT_PARAMS(curr),
331 p2i(curr->prev_top_at_mark_start()),
332 p2i(curr->next_top_at_mark_start()),
333 curr->age_in_surv_rate_group_cond());
334 curr = curr->get_next_young_region();
335 }
336 }
337
338 gclog_or_tty->cr();
339 }
340
341 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
342 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
343 }
344
345 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
346 // The from card cache is not the memory that is actually committed. So we cannot
347 // take advantage of the zero_filled parameter.
348 reset_from_card_cache(start_idx, num_regions);
349 }
350
351 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
352 {
353 // Claim the right to put the region on the dirty cards region list
354 // by installing a self pointer.
355 HeapRegion* next = hr->get_next_dirty_cards_region();
356 if (next == NULL) {
357 HeapRegion* res = (HeapRegion*)
358 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
359 NULL);
360 if (res == NULL) {
361 HeapRegion* head;
362 do {
363 // Put the region to the dirty cards region list.
364 head = _dirty_cards_region_list;
365 next = (HeapRegion*)
366 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
367 if (next == head) {
368 assert(hr->get_next_dirty_cards_region() == hr,
369 "hr->get_next_dirty_cards_region() != hr");
370 if (next == NULL) {
371 // The last region in the list points to itself.
372 hr->set_next_dirty_cards_region(hr);
373 } else {
374 hr->set_next_dirty_cards_region(next);
375 }
376 }
377 } while (next != head);
378 }
379 }
380 }
381
382 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
383 {
384 HeapRegion* head;
385 HeapRegion* hr;
386 do {
387 head = _dirty_cards_region_list;
388 if (head == NULL) {
389 return NULL;
390 }
391 HeapRegion* new_head = head->get_next_dirty_cards_region();
392 if (head == new_head) {
393 // The last region.
394 new_head = NULL;
395 }
396 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
397 head);
398 } while (hr != head);
399 assert(hr != NULL, "invariant");
400 hr->set_next_dirty_cards_region(NULL);
401 return hr;
402 }
403
404 // Returns true if the reference points to an object that
405 // can move in an incremental collection.
406 bool G1CollectedHeap::is_scavengable(const void* p) {
407 HeapRegion* hr = heap_region_containing(p);
408 return !hr->is_pinned();
409 }
410
411 // Private methods.
412
413 HeapRegion*
414 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
415 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
416 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
417 if (!_secondary_free_list.is_empty()) {
418 if (G1ConcRegionFreeingVerbose) {
419 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
420 "secondary_free_list has %u entries",
421 _secondary_free_list.length());
422 }
423 // It looks as if there are free regions available on the
424 // secondary_free_list. Let's move them to the free_list and try
425 // again to allocate from it.
426 append_secondary_free_list();
427
428 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
429 "empty we should have moved at least one entry to the free_list");
430 HeapRegion* res = _hrm.allocate_free_region(is_old);
431 if (G1ConcRegionFreeingVerbose) {
432 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
433 "allocated "HR_FORMAT" from secondary_free_list",
434 HR_FORMAT_PARAMS(res));
435 }
436 return res;
437 }
438
439 // Wait here until we get notified either when (a) there are no
440 // more free regions coming or (b) some regions have been moved on
441 // the secondary_free_list.
442 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
443 }
444
445 if (G1ConcRegionFreeingVerbose) {
446 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
447 "could not allocate from secondary_free_list");
448 }
449 return NULL;
450 }
451
452 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
453 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
454 "the only time we use this to allocate a humongous region is "
455 "when we are allocating a single humongous region");
456
457 HeapRegion* res;
458 if (G1StressConcRegionFreeing) {
459 if (!_secondary_free_list.is_empty()) {
460 if (G1ConcRegionFreeingVerbose) {
461 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
462 "forced to look at the secondary_free_list");
463 }
464 res = new_region_try_secondary_free_list(is_old);
465 if (res != NULL) {
466 return res;
467 }
468 }
469 }
470
471 res = _hrm.allocate_free_region(is_old);
472
473 if (res == NULL) {
474 if (G1ConcRegionFreeingVerbose) {
475 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
476 "res == NULL, trying the secondary_free_list");
477 }
478 res = new_region_try_secondary_free_list(is_old);
479 }
480 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
481 // Currently, only attempts to allocate GC alloc regions set
482 // do_expand to true. So, we should only reach here during a
483 // safepoint. If this assumption changes we might have to
484 // reconsider the use of _expand_heap_after_alloc_failure.
485 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
486
487 ergo_verbose1(ErgoHeapSizing,
488 "attempt heap expansion",
489 ergo_format_reason("region allocation request failed")
490 ergo_format_byte("allocation request"),
491 word_size * HeapWordSize);
492 if (expand(word_size * HeapWordSize)) {
493 // Given that expand() succeeded in expanding the heap, and we
494 // always expand the heap by an amount aligned to the heap
495 // region size, the free list should in theory not be empty.
496 // In either case allocate_free_region() will check for NULL.
497 res = _hrm.allocate_free_region(is_old);
498 } else {
499 _expand_heap_after_alloc_failure = false;
500 }
501 }
502 return res;
503 }
504
505 HeapWord*
506 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
507 uint num_regions,
508 size_t word_size,
509 AllocationContext_t context) {
510 assert(first != G1_NO_HRM_INDEX, "pre-condition");
511 assert(is_humongous(word_size), "word_size should be humongous");
512 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
513
514 // Index of last region in the series + 1.
515 uint last = first + num_regions;
516
517 // We need to initialize the region(s) we just discovered. This is
518 // a bit tricky given that it can happen concurrently with
519 // refinement threads refining cards on these regions and
520 // potentially wanting to refine the BOT as they are scanning
521 // those cards (this can happen shortly after a cleanup; see CR
522 // 6991377). So we have to set up the region(s) carefully and in
523 // a specific order.
524
525 // The word size sum of all the regions we will allocate.
526 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
527 assert(word_size <= word_size_sum, "sanity");
528
529 // This will be the "starts humongous" region.
530 HeapRegion* first_hr = region_at(first);
531 // The header of the new object will be placed at the bottom of
532 // the first region.
533 HeapWord* new_obj = first_hr->bottom();
534 // This will be the new end of the first region in the series that
535 // should also match the end of the last region in the series.
536 HeapWord* new_end = new_obj + word_size_sum;
537 // This will be the new top of the first region that will reflect
538 // this allocation.
539 HeapWord* new_top = new_obj + word_size;
540
541 // First, we need to zero the header of the space that we will be
542 // allocating. When we update top further down, some refinement
543 // threads might try to scan the region. By zeroing the header we
544 // ensure that any thread that will try to scan the region will
545 // come across the zero klass word and bail out.
546 //
547 // NOTE: It would not have been correct to have used
548 // CollectedHeap::fill_with_object() and make the space look like
549 // an int array. The thread that is doing the allocation will
550 // later update the object header to a potentially different array
551 // type and, for a very short period of time, the klass and length
552 // fields will be inconsistent. This could cause a refinement
553 // thread to calculate the object size incorrectly.
554 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
555
556 // We will set up the first region as "starts humongous". This
557 // will also update the BOT covering all the regions to reflect
558 // that there is a single object that starts at the bottom of the
559 // first region.
560 first_hr->set_starts_humongous(new_top, new_end);
561 first_hr->set_allocation_context(context);
562 // Then, if there are any, we will set up the "continues
563 // humongous" regions.
564 HeapRegion* hr = NULL;
565 for (uint i = first + 1; i < last; ++i) {
566 hr = region_at(i);
567 hr->set_continues_humongous(first_hr);
568 hr->set_allocation_context(context);
569 }
570 // If we have "continues humongous" regions (hr != NULL), then the
571 // end of the last one should match new_end.
572 assert(hr == NULL || hr->end() == new_end, "sanity");
573
574 // Up to this point no concurrent thread would have been able to
575 // do any scanning on any region in this series. All the top
576 // fields still point to bottom, so the intersection between
577 // [bottom,top] and [card_start,card_end] will be empty. Before we
578 // update the top fields, we'll do a storestore to make sure that
579 // no thread sees the update to top before the zeroing of the
580 // object header and the BOT initialization.
581 OrderAccess::storestore();
582
583 // Now that the BOT and the object header have been initialized,
584 // we can update top of the "starts humongous" region.
585 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
586 "new_top should be in this region");
587 first_hr->set_top(new_top);
588 if (_hr_printer.is_active()) {
589 HeapWord* bottom = first_hr->bottom();
590 HeapWord* end = first_hr->orig_end();
591 if ((first + 1) == last) {
592 // the series has a single humongous region
593 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
594 } else {
595 // the series has more than one humongous regions
596 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
597 }
598 }
599
600 // Now, we will update the top fields of the "continues humongous"
601 // regions. The reason we need to do this is that, otherwise,
602 // these regions would look empty and this will confuse parts of
603 // G1. For example, the code that looks for a consecutive number
604 // of empty regions will consider them empty and try to
605 // re-allocate them. We can extend is_empty() to also include
606 // !is_continues_humongous(), but it is easier to just update the top
607 // fields here. The way we set top for all regions (i.e., top ==
608 // end for all regions but the last one, top == new_top for the
609 // last one) is actually used when we will free up the humongous
610 // region in free_humongous_region().
611 hr = NULL;
612 for (uint i = first + 1; i < last; ++i) {
613 hr = region_at(i);
614 if ((i + 1) == last) {
615 // last continues humongous region
616 assert(hr->bottom() < new_top && new_top <= hr->end(),
617 "new_top should fall on this region");
618 hr->set_top(new_top);
619 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
620 } else {
621 // not last one
622 assert(new_top > hr->end(), "new_top should be above this region");
623 hr->set_top(hr->end());
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
625 }
626 }
627 // If we have continues humongous regions (hr != NULL), then the
628 // end of the last one should match new_end and its top should
629 // match new_top.
630 assert(hr == NULL ||
631 (hr->end() == new_end && hr->top() == new_top), "sanity");
632 check_bitmaps("Humongous Region Allocation", first_hr);
633
634 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
635 _allocator->increase_used(first_hr->used());
636 _humongous_set.add(first_hr);
637
638 return new_obj;
639 }
640
641 // If could fit into free regions w/o expansion, try.
642 // Otherwise, if can expand, do so.
643 // Otherwise, if using ex regions might help, try with ex given back.
644 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
645 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
646
647 verify_region_sets_optional();
648
649 uint first = G1_NO_HRM_INDEX;
650 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
651
652 if (obj_regions == 1) {
653 // Only one region to allocate, try to use a fast path by directly allocating
654 // from the free lists. Do not try to expand here, we will potentially do that
655 // later.
656 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
657 if (hr != NULL) {
658 first = hr->hrm_index();
659 }
660 } else {
661 // We can't allocate humongous regions spanning more than one region while
662 // cleanupComplete() is running, since some of the regions we find to be
663 // empty might not yet be added to the free list. It is not straightforward
664 // to know in which list they are on so that we can remove them. We only
665 // need to do this if we need to allocate more than one region to satisfy the
666 // current humongous allocation request. If we are only allocating one region
667 // we use the one-region region allocation code (see above), that already
668 // potentially waits for regions from the secondary free list.
669 wait_while_free_regions_coming();
670 append_secondary_free_list_if_not_empty_with_lock();
671
672 // Policy: Try only empty regions (i.e. already committed first). Maybe we
673 // are lucky enough to find some.
674 first = _hrm.find_contiguous_only_empty(obj_regions);
675 if (first != G1_NO_HRM_INDEX) {
676 _hrm.allocate_free_regions_starting_at(first, obj_regions);
677 }
678 }
679
680 if (first == G1_NO_HRM_INDEX) {
681 // Policy: We could not find enough regions for the humongous object in the
682 // free list. Look through the heap to find a mix of free and uncommitted regions.
683 // If so, try expansion.
684 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
685 if (first != G1_NO_HRM_INDEX) {
686 // We found something. Make sure these regions are committed, i.e. expand
687 // the heap. Alternatively we could do a defragmentation GC.
688 ergo_verbose1(ErgoHeapSizing,
689 "attempt heap expansion",
690 ergo_format_reason("humongous allocation request failed")
691 ergo_format_byte("allocation request"),
692 word_size * HeapWordSize);
693
694 _hrm.expand_at(first, obj_regions);
695 g1_policy()->record_new_heap_size(num_regions());
696
697 #ifdef ASSERT
698 for (uint i = first; i < first + obj_regions; ++i) {
699 HeapRegion* hr = region_at(i);
700 assert(hr->is_free(), "sanity");
701 assert(hr->is_empty(), "sanity");
702 assert(is_on_master_free_list(hr), "sanity");
703 }
704 #endif
705 _hrm.allocate_free_regions_starting_at(first, obj_regions);
706 } else {
707 // Policy: Potentially trigger a defragmentation GC.
708 }
709 }
710
711 HeapWord* result = NULL;
712 if (first != G1_NO_HRM_INDEX) {
713 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
714 word_size, context);
715 assert(result != NULL, "it should always return a valid result");
716
717 // A successful humongous object allocation changes the used space
718 // information of the old generation so we need to recalculate the
719 // sizes and update the jstat counters here.
720 g1mm()->update_sizes();
721 }
722
723 verify_region_sets_optional();
724
725 return result;
726 }
727
728 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
729 assert_heap_not_locked_and_not_at_safepoint();
730 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
731
732 uint dummy_gc_count_before;
733 uint dummy_gclocker_retry_count = 0;
734 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
735 }
736
737 HeapWord*
738 G1CollectedHeap::mem_allocate(size_t word_size,
739 bool* gc_overhead_limit_was_exceeded) {
740 assert_heap_not_locked_and_not_at_safepoint();
741
742 // Loop until the allocation is satisfied, or unsatisfied after GC.
743 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
744 uint gc_count_before;
745
746 HeapWord* result = NULL;
747 if (!is_humongous(word_size)) {
748 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
749 } else {
750 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
751 }
752 if (result != NULL) {
753 return result;
754 }
755
756 // Create the garbage collection operation...
757 VM_G1CollectForAllocation op(gc_count_before, word_size);
758 op.set_allocation_context(AllocationContext::current());
759
760 // ...and get the VM thread to execute it.
761 VMThread::execute(&op);
762
763 if (op.prologue_succeeded() && op.pause_succeeded()) {
764 // If the operation was successful we'll return the result even
765 // if it is NULL. If the allocation attempt failed immediately
766 // after a Full GC, it's unlikely we'll be able to allocate now.
767 HeapWord* result = op.result();
768 if (result != NULL && !is_humongous(word_size)) {
769 // Allocations that take place on VM operations do not do any
770 // card dirtying and we have to do it here. We only have to do
771 // this for non-humongous allocations, though.
772 dirty_young_block(result, word_size);
773 }
774 return result;
775 } else {
776 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
777 return NULL;
778 }
779 assert(op.result() == NULL,
780 "the result should be NULL if the VM op did not succeed");
781 }
782
783 // Give a warning if we seem to be looping forever.
784 if ((QueuedAllocationWarningCount > 0) &&
785 (try_count % QueuedAllocationWarningCount == 0)) {
786 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
787 }
788 }
789
790 ShouldNotReachHere();
791 return NULL;
792 }
793
794 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
795 AllocationContext_t context,
796 uint* gc_count_before_ret,
797 uint* gclocker_retry_count_ret) {
798 // Make sure you read the note in attempt_allocation_humongous().
799
800 assert_heap_not_locked_and_not_at_safepoint();
801 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
802 "be called for humongous allocation requests");
803
804 // We should only get here after the first-level allocation attempt
805 // (attempt_allocation()) failed to allocate.
806
807 // We will loop until a) we manage to successfully perform the
808 // allocation or b) we successfully schedule a collection which
809 // fails to perform the allocation. b) is the only case when we'll
810 // return NULL.
811 HeapWord* result = NULL;
812 for (int try_count = 1; /* we'll return */; try_count += 1) {
813 bool should_try_gc;
814 uint gc_count_before;
815
816 {
817 MutexLockerEx x(Heap_lock);
818 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
819 false /* bot_updates */);
820 if (result != NULL) {
821 return result;
822 }
823
824 // If we reach here, attempt_allocation_locked() above failed to
825 // allocate a new region. So the mutator alloc region should be NULL.
826 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
827
828 if (GC_locker::is_active_and_needs_gc()) {
829 if (g1_policy()->can_expand_young_list()) {
830 // No need for an ergo verbose message here,
831 // can_expand_young_list() does this when it returns true.
832 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
833 false /* bot_updates */);
834 if (result != NULL) {
835 return result;
836 }
837 }
838 should_try_gc = false;
839 } else {
840 // The GCLocker may not be active but the GCLocker initiated
841 // GC may not yet have been performed (GCLocker::needs_gc()
842 // returns true). In this case we do not try this GC and
843 // wait until the GCLocker initiated GC is performed, and
844 // then retry the allocation.
845 if (GC_locker::needs_gc()) {
846 should_try_gc = false;
847 } else {
848 // Read the GC count while still holding the Heap_lock.
849 gc_count_before = total_collections();
850 should_try_gc = true;
851 }
852 }
853 }
854
855 if (should_try_gc) {
856 bool succeeded;
857 result = do_collection_pause(word_size, gc_count_before, &succeeded,
858 GCCause::_g1_inc_collection_pause);
859 if (result != NULL) {
860 assert(succeeded, "only way to get back a non-NULL result");
861 return result;
862 }
863
864 if (succeeded) {
865 // If we get here we successfully scheduled a collection which
866 // failed to allocate. No point in trying to allocate
867 // further. We'll just return NULL.
868 MutexLockerEx x(Heap_lock);
869 *gc_count_before_ret = total_collections();
870 return NULL;
871 }
872 } else {
873 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
874 MutexLockerEx x(Heap_lock);
875 *gc_count_before_ret = total_collections();
876 return NULL;
877 }
878 // The GCLocker is either active or the GCLocker initiated
879 // GC has not yet been performed. Stall until it is and
880 // then retry the allocation.
881 GC_locker::stall_until_clear();
882 (*gclocker_retry_count_ret) += 1;
883 }
884
885 // We can reach here if we were unsuccessful in scheduling a
886 // collection (because another thread beat us to it) or if we were
887 // stalled due to the GC locker. In either can we should retry the
888 // allocation attempt in case another thread successfully
889 // performed a collection and reclaimed enough space. We do the
890 // first attempt (without holding the Heap_lock) here and the
891 // follow-on attempt will be at the start of the next loop
892 // iteration (after taking the Heap_lock).
893 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
894 false /* bot_updates */);
895 if (result != NULL) {
896 return result;
897 }
898
899 // Give a warning if we seem to be looping forever.
900 if ((QueuedAllocationWarningCount > 0) &&
901 (try_count % QueuedAllocationWarningCount == 0)) {
902 warning("G1CollectedHeap::attempt_allocation_slow() "
903 "retries %d times", try_count);
904 }
905 }
906
907 ShouldNotReachHere();
908 return NULL;
909 }
910
911 void G1CollectedHeap::begin_archive_alloc_range() {
912 assert_at_safepoint(true /* should_be_vm_thread */);
913 if (_archive_allocator == NULL) {
914 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
915 }
916 }
917
918 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
919 // Allocations in archive regions cannot be of a size that would be considered
920 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
921 // may be different at archive-restore time.
922 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
923 }
924
925 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
926 assert_at_safepoint(true /* should_be_vm_thread */);
927 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
928 if (is_archive_alloc_too_large(word_size)) {
929 return NULL;
930 }
931 return _archive_allocator->archive_mem_allocate(word_size);
932 }
933
934 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
935 size_t end_alignment_in_bytes) {
936 assert_at_safepoint(true /* should_be_vm_thread */);
937 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
938
939 // Call complete_archive to do the real work, filling in the MemRegion
940 // array with the archive regions.
941 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
942 delete _archive_allocator;
943 _archive_allocator = NULL;
944 }
945
946 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
947 assert(ranges != NULL, "MemRegion array NULL");
948 assert(count != 0, "No MemRegions provided");
949 MemRegion reserved = _hrm.reserved();
950 for (size_t i = 0; i < count; i++) {
951 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
952 return false;
953 }
954 }
955 return true;
956 }
957
958 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
959 assert(ranges != NULL, "MemRegion array NULL");
960 assert(count != 0, "No MemRegions provided");
961 MutexLockerEx x(Heap_lock);
962
963 MemRegion reserved = _hrm.reserved();
964 HeapWord* prev_last_addr = NULL;
965 HeapRegion* prev_last_region = NULL;
966
967 // Temporarily disable pretouching of heap pages. This interface is used
968 // when mmap'ing archived heap data in, so pre-touching is wasted.
969 FlagSetting fs(AlwaysPreTouch, false);
970
971 // Enable archive object checking in G1MarkSweep. We have to let it know
972 // about each archive range, so that objects in those ranges aren't marked.
973 G1MarkSweep::enable_archive_object_check();
974
975 // For each specified MemRegion range, allocate the corresponding G1
976 // regions and mark them as archive regions. We expect the ranges in
977 // ascending starting address order, without overlap.
978 for (size_t i = 0; i < count; i++) {
979 MemRegion curr_range = ranges[i];
980 HeapWord* start_address = curr_range.start();
981 size_t word_size = curr_range.word_size();
982 HeapWord* last_address = curr_range.last();
983 size_t commits = 0;
984
985 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
986 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
987 p2i(start_address), p2i(last_address)));
988 guarantee(start_address > prev_last_addr,
989 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
990 p2i(start_address), p2i(prev_last_addr)));
991 prev_last_addr = last_address;
992
993 // Check for ranges that start in the same G1 region in which the previous
994 // range ended, and adjust the start address so we don't try to allocate
995 // the same region again. If the current range is entirely within that
996 // region, skip it, just adjusting the recorded top.
997 HeapRegion* start_region = _hrm.addr_to_region(start_address);
998 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
999 start_address = start_region->end();
1000 if (start_address > last_address) {
1001 _allocator->increase_used(word_size * HeapWordSize);
1002 start_region->set_top(last_address + 1);
1003 continue;
1004 }
1005 start_region->set_top(start_address);
1006 curr_range = MemRegion(start_address, last_address + 1);
1007 start_region = _hrm.addr_to_region(start_address);
1008 }
1009
1010 // Perform the actual region allocation, exiting if it fails.
1011 // Then note how much new space we have allocated.
1012 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1013 return false;
1014 }
1015 _allocator->increase_used(word_size * HeapWordSize);
1016 if (commits != 0) {
1017 ergo_verbose1(ErgoHeapSizing,
1018 "attempt heap expansion",
1019 ergo_format_reason("allocate archive regions")
1020 ergo_format_byte("total size"),
1021 HeapRegion::GrainWords * HeapWordSize * commits);
1022 }
1023
1024 // Mark each G1 region touched by the range as archive, add it to the old set,
1025 // and set the allocation context and top.
1026 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1027 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1028 prev_last_region = last_region;
1029
1030 while (curr_region != NULL) {
1031 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1032 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1033 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1034 curr_region->set_allocation_context(AllocationContext::system());
1035 curr_region->set_archive();
1036 _old_set.add(curr_region);
1037 if (curr_region != last_region) {
1038 curr_region->set_top(curr_region->end());
1039 curr_region = _hrm.next_region_in_heap(curr_region);
1040 } else {
1041 curr_region->set_top(last_address + 1);
1042 curr_region = NULL;
1043 }
1044 }
1045
1046 // Notify mark-sweep of the archive range.
1047 G1MarkSweep::mark_range_archive(curr_range);
1048 }
1049 return true;
1050 }
1051
1052 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1053 assert(ranges != NULL, "MemRegion array NULL");
1054 assert(count != 0, "No MemRegions provided");
1055 MemRegion reserved = _hrm.reserved();
1056 HeapWord *prev_last_addr = NULL;
1057 HeapRegion* prev_last_region = NULL;
1058
1059 // For each MemRegion, create filler objects, if needed, in the G1 regions
1060 // that contain the address range. The address range actually within the
1061 // MemRegion will not be modified. That is assumed to have been initialized
1062 // elsewhere, probably via an mmap of archived heap data.
1063 MutexLockerEx x(Heap_lock);
1064 for (size_t i = 0; i < count; i++) {
1065 HeapWord* start_address = ranges[i].start();
1066 HeapWord* last_address = ranges[i].last();
1067
1068 assert(reserved.contains(start_address) && reserved.contains(last_address),
1069 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1070 p2i(start_address), p2i(last_address)));
1071 assert(start_address > prev_last_addr,
1072 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1073 p2i(start_address), p2i(prev_last_addr)));
1074
1075 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1076 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1077 HeapWord* bottom_address = start_region->bottom();
1078
1079 // Check for a range beginning in the same region in which the
1080 // previous one ended.
1081 if (start_region == prev_last_region) {
1082 bottom_address = prev_last_addr + 1;
1083 }
1084
1085 // Verify that the regions were all marked as archive regions by
1086 // alloc_archive_regions.
1087 HeapRegion* curr_region = start_region;
1088 while (curr_region != NULL) {
1089 guarantee(curr_region->is_archive(),
1090 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1091 if (curr_region != last_region) {
1092 curr_region = _hrm.next_region_in_heap(curr_region);
1093 } else {
1094 curr_region = NULL;
1095 }
1096 }
1097
1098 prev_last_addr = last_address;
1099 prev_last_region = last_region;
1100
1101 // Fill the memory below the allocated range with dummy object(s),
1102 // if the region bottom does not match the range start, or if the previous
1103 // range ended within the same G1 region, and there is a gap.
1104 if (start_address != bottom_address) {
1105 size_t fill_size = pointer_delta(start_address, bottom_address);
1106 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1107 _allocator->increase_used(fill_size * HeapWordSize);
1108 }
1109 }
1110 }
1111
1112 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1113 uint* gc_count_before_ret,
1114 uint* gclocker_retry_count_ret) {
1115 // The structure of this method has a lot of similarities to
1116 // attempt_allocation_slow(). The reason these two were not merged
1117 // into a single one is that such a method would require several "if
1118 // allocation is not humongous do this, otherwise do that"
1119 // conditional paths which would obscure its flow. In fact, an early
1120 // version of this code did use a unified method which was harder to
1121 // follow and, as a result, it had subtle bugs that were hard to
1122 // track down. So keeping these two methods separate allows each to
1123 // be more readable. It will be good to keep these two in sync as
1124 // much as possible.
1125
1126 assert_heap_not_locked_and_not_at_safepoint();
1127 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1128 "should only be called for humongous allocations");
1129
1130 // Humongous objects can exhaust the heap quickly, so we should check if we
1131 // need to start a marking cycle at each humongous object allocation. We do
1132 // the check before we do the actual allocation. The reason for doing it
1133 // before the allocation is that we avoid having to keep track of the newly
1134 // allocated memory while we do a GC.
1135 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1136 word_size)) {
1137 collect(GCCause::_g1_humongous_allocation);
1138 }
1139
1140 // We will loop until a) we manage to successfully perform the
1141 // allocation or b) we successfully schedule a collection which
1142 // fails to perform the allocation. b) is the only case when we'll
1143 // return NULL.
1144 HeapWord* result = NULL;
1145 for (int try_count = 1; /* we'll return */; try_count += 1) {
1146 bool should_try_gc;
1147 uint gc_count_before;
1148
1149 {
1150 MutexLockerEx x(Heap_lock);
1151
1152 // Given that humongous objects are not allocated in young
1153 // regions, we'll first try to do the allocation without doing a
1154 // collection hoping that there's enough space in the heap.
1155 result = humongous_obj_allocate(word_size, AllocationContext::current());
1156 if (result != NULL) {
1157 return result;
1158 }
1159
1160 if (GC_locker::is_active_and_needs_gc()) {
1161 should_try_gc = false;
1162 } else {
1163 // The GCLocker may not be active but the GCLocker initiated
1164 // GC may not yet have been performed (GCLocker::needs_gc()
1165 // returns true). In this case we do not try this GC and
1166 // wait until the GCLocker initiated GC is performed, and
1167 // then retry the allocation.
1168 if (GC_locker::needs_gc()) {
1169 should_try_gc = false;
1170 } else {
1171 // Read the GC count while still holding the Heap_lock.
1172 gc_count_before = total_collections();
1173 should_try_gc = true;
1174 }
1175 }
1176 }
1177
1178 if (should_try_gc) {
1179 // If we failed to allocate the humongous object, we should try to
1180 // do a collection pause (if we're allowed) in case it reclaims
1181 // enough space for the allocation to succeed after the pause.
1182
1183 bool succeeded;
1184 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1185 GCCause::_g1_humongous_allocation);
1186 if (result != NULL) {
1187 assert(succeeded, "only way to get back a non-NULL result");
1188 return result;
1189 }
1190
1191 if (succeeded) {
1192 // If we get here we successfully scheduled a collection which
1193 // failed to allocate. No point in trying to allocate
1194 // further. We'll just return NULL.
1195 MutexLockerEx x(Heap_lock);
1196 *gc_count_before_ret = total_collections();
1197 return NULL;
1198 }
1199 } else {
1200 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1201 MutexLockerEx x(Heap_lock);
1202 *gc_count_before_ret = total_collections();
1203 return NULL;
1204 }
1205 // The GCLocker is either active or the GCLocker initiated
1206 // GC has not yet been performed. Stall until it is and
1207 // then retry the allocation.
1208 GC_locker::stall_until_clear();
1209 (*gclocker_retry_count_ret) += 1;
1210 }
1211
1212 // We can reach here if we were unsuccessful in scheduling a
1213 // collection (because another thread beat us to it) or if we were
1214 // stalled due to the GC locker. In either can we should retry the
1215 // allocation attempt in case another thread successfully
1216 // performed a collection and reclaimed enough space. Give a
1217 // warning if we seem to be looping forever.
1218
1219 if ((QueuedAllocationWarningCount > 0) &&
1220 (try_count % QueuedAllocationWarningCount == 0)) {
1221 warning("G1CollectedHeap::attempt_allocation_humongous() "
1222 "retries %d times", try_count);
1223 }
1224 }
1225
1226 ShouldNotReachHere();
1227 return NULL;
1228 }
1229
1230 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1231 AllocationContext_t context,
1232 bool expect_null_mutator_alloc_region) {
1233 assert_at_safepoint(true /* should_be_vm_thread */);
1234 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1235 !expect_null_mutator_alloc_region,
1236 "the current alloc region was unexpectedly found to be non-NULL");
1237
1238 if (!is_humongous(word_size)) {
1239 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1240 false /* bot_updates */);
1241 } else {
1242 HeapWord* result = humongous_obj_allocate(word_size, context);
1243 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1244 collector_state()->set_initiate_conc_mark_if_possible(true);
1245 }
1246 return result;
1247 }
1248
1249 ShouldNotReachHere();
1250 }
1251
1252 class PostMCRemSetClearClosure: public HeapRegionClosure {
1253 G1CollectedHeap* _g1h;
1254 ModRefBarrierSet* _mr_bs;
1255 public:
1256 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1257 _g1h(g1h), _mr_bs(mr_bs) {}
1258
1259 bool doHeapRegion(HeapRegion* r) {
1260 HeapRegionRemSet* hrrs = r->rem_set();
1261
1262 if (r->is_continues_humongous()) {
1263 // We'll assert that the strong code root list and RSet is empty
1264 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1265 assert(hrrs->occupied() == 0, "RSet should be empty");
1266 return false;
1267 }
1268
1269 _g1h->reset_gc_time_stamps(r);
1270 hrrs->clear();
1271 // You might think here that we could clear just the cards
1272 // corresponding to the used region. But no: if we leave a dirty card
1273 // in a region we might allocate into, then it would prevent that card
1274 // from being enqueued, and cause it to be missed.
1275 // Re: the performance cost: we shouldn't be doing full GC anyway!
1276 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1277
1278 return false;
1279 }
1280 };
1281
1282 void G1CollectedHeap::clear_rsets_post_compaction() {
1283 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1284 heap_region_iterate(&rs_clear);
1285 }
1286
1287 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1288 G1CollectedHeap* _g1h;
1289 UpdateRSOopClosure _cl;
1290 public:
1291 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1292 _cl(g1->g1_rem_set(), worker_i),
1293 _g1h(g1)
1294 { }
1295
1296 bool doHeapRegion(HeapRegion* r) {
1297 if (!r->is_continues_humongous()) {
1298 _cl.set_from(r);
1299 r->oop_iterate(&_cl);
1300 }
1301 return false;
1302 }
1303 };
1304
1305 class ParRebuildRSTask: public AbstractGangTask {
1306 G1CollectedHeap* _g1;
1307 HeapRegionClaimer _hrclaimer;
1308
1309 public:
1310 ParRebuildRSTask(G1CollectedHeap* g1) :
1311 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1312
1313 void work(uint worker_id) {
1314 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1315 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1316 }
1317 };
1318
1319 class PostCompactionPrinterClosure: public HeapRegionClosure {
1320 private:
1321 G1HRPrinter* _hr_printer;
1322 public:
1323 bool doHeapRegion(HeapRegion* hr) {
1324 assert(!hr->is_young(), "not expecting to find young regions");
1325 if (hr->is_free()) {
1326 // We only generate output for non-empty regions.
1327 } else if (hr->is_starts_humongous()) {
1328 if (hr->region_num() == 1) {
1329 // single humongous region
1330 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1331 } else {
1332 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1333 }
1334 } else if (hr->is_continues_humongous()) {
1335 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1336 } else if (hr->is_archive()) {
1337 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1338 } else if (hr->is_old()) {
1339 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1340 } else {
1341 ShouldNotReachHere();
1342 }
1343 return false;
1344 }
1345
1346 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1347 : _hr_printer(hr_printer) { }
1348 };
1349
1350 void G1CollectedHeap::print_hrm_post_compaction() {
1351 PostCompactionPrinterClosure cl(hr_printer());
1352 heap_region_iterate(&cl);
1353 }
1354
1355 bool G1CollectedHeap::do_collection(bool explicit_gc,
1356 bool clear_all_soft_refs,
1357 size_t word_size) {
1358 assert_at_safepoint(true /* should_be_vm_thread */);
1359
1360 if (GC_locker::check_active_before_gc()) {
1361 return false;
1362 }
1363
1364 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1365 gc_timer->register_gc_start();
1366
1367 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1368 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1369
1370 SvcGCMarker sgcm(SvcGCMarker::FULL);
1371 ResourceMark rm;
1372
1373 G1Log::update_level();
1374 print_heap_before_gc();
1375 trace_heap_before_gc(gc_tracer);
1376
1377 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1378
1379 verify_region_sets_optional();
1380
1381 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1382 collector_policy()->should_clear_all_soft_refs();
1383
1384 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1385
1386 {
1387 IsGCActiveMark x;
1388
1389 // Timing
1390 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1391 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1392
1393 {
1394 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1395 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1396 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1397
1398 g1_policy()->record_full_collection_start();
1399
1400 // Note: When we have a more flexible GC logging framework that
1401 // allows us to add optional attributes to a GC log record we
1402 // could consider timing and reporting how long we wait in the
1403 // following two methods.
1404 wait_while_free_regions_coming();
1405 // If we start the compaction before the CM threads finish
1406 // scanning the root regions we might trip them over as we'll
1407 // be moving objects / updating references. So let's wait until
1408 // they are done. By telling them to abort, they should complete
1409 // early.
1410 _cm->root_regions()->abort();
1411 _cm->root_regions()->wait_until_scan_finished();
1412 append_secondary_free_list_if_not_empty_with_lock();
1413
1414 gc_prologue(true);
1415 increment_total_collections(true /* full gc */);
1416 increment_old_marking_cycles_started();
1417
1418 assert(used() == recalculate_used(), "Should be equal");
1419
1420 verify_before_gc();
1421
1422 check_bitmaps("Full GC Start");
1423 pre_full_gc_dump(gc_timer);
1424
1425 COMPILER2_PRESENT(DerivedPointerTable::clear());
1426
1427 // Disable discovery and empty the discovered lists
1428 // for the CM ref processor.
1429 ref_processor_cm()->disable_discovery();
1430 ref_processor_cm()->abandon_partial_discovery();
1431 ref_processor_cm()->verify_no_references_recorded();
1432
1433 // Abandon current iterations of concurrent marking and concurrent
1434 // refinement, if any are in progress. We have to do this before
1435 // wait_until_scan_finished() below.
1436 concurrent_mark()->abort();
1437
1438 // Make sure we'll choose a new allocation region afterwards.
1439 _allocator->release_mutator_alloc_region();
1440 _allocator->abandon_gc_alloc_regions();
1441 g1_rem_set()->cleanupHRRS();
1442
1443 // We should call this after we retire any currently active alloc
1444 // regions so that all the ALLOC / RETIRE events are generated
1445 // before the start GC event.
1446 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1447
1448 // We may have added regions to the current incremental collection
1449 // set between the last GC or pause and now. We need to clear the
1450 // incremental collection set and then start rebuilding it afresh
1451 // after this full GC.
1452 abandon_collection_set(g1_policy()->inc_cset_head());
1453 g1_policy()->clear_incremental_cset();
1454 g1_policy()->stop_incremental_cset_building();
1455
1456 tear_down_region_sets(false /* free_list_only */);
1457 collector_state()->set_gcs_are_young(true);
1458
1459 // See the comments in g1CollectedHeap.hpp and
1460 // G1CollectedHeap::ref_processing_init() about
1461 // how reference processing currently works in G1.
1462
1463 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1464 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1465
1466 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1467 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1468
1469 ref_processor_stw()->enable_discovery();
1470 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1471
1472 // Do collection work
1473 {
1474 HandleMark hm; // Discard invalid handles created during gc
1475 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1476 }
1477
1478 assert(num_free_regions() == 0, "we should not have added any free regions");
1479 rebuild_region_sets(false /* free_list_only */);
1480
1481 // Enqueue any discovered reference objects that have
1482 // not been removed from the discovered lists.
1483 ref_processor_stw()->enqueue_discovered_references();
1484
1485 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1486
1487 MemoryService::track_memory_usage();
1488
1489 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1490 ref_processor_stw()->verify_no_references_recorded();
1491
1492 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1493 ClassLoaderDataGraph::purge();
1494 MetaspaceAux::verify_metrics();
1495
1496 // Note: since we've just done a full GC, concurrent
1497 // marking is no longer active. Therefore we need not
1498 // re-enable reference discovery for the CM ref processor.
1499 // That will be done at the start of the next marking cycle.
1500 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1501 ref_processor_cm()->verify_no_references_recorded();
1502
1503 reset_gc_time_stamp();
1504 // Since everything potentially moved, we will clear all remembered
1505 // sets, and clear all cards. Later we will rebuild remembered
1506 // sets. We will also reset the GC time stamps of the regions.
1507 clear_rsets_post_compaction();
1508 check_gc_time_stamps();
1509
1510 // Resize the heap if necessary.
1511 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1512
1513 if (_hr_printer.is_active()) {
1514 // We should do this after we potentially resize the heap so
1515 // that all the COMMIT / UNCOMMIT events are generated before
1516 // the end GC event.
1517
1518 print_hrm_post_compaction();
1519 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1520 }
1521
1522 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1523 if (hot_card_cache->use_cache()) {
1524 hot_card_cache->reset_card_counts();
1525 hot_card_cache->reset_hot_cache();
1526 }
1527
1528 // Rebuild remembered sets of all regions.
1529 uint n_workers =
1530 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1531 workers()->active_workers(),
1532 Threads::number_of_non_daemon_threads());
1533 workers()->set_active_workers(n_workers);
1534
1535 ParRebuildRSTask rebuild_rs_task(this);
1536 workers()->run_task(&rebuild_rs_task);
1537
1538 // Rebuild the strong code root lists for each region
1539 rebuild_strong_code_roots();
1540
1541 if (true) { // FIXME
1542 MetaspaceGC::compute_new_size();
1543 }
1544
1545 #ifdef TRACESPINNING
1546 ParallelTaskTerminator::print_termination_counts();
1547 #endif
1548
1549 // Discard all rset updates
1550 JavaThread::dirty_card_queue_set().abandon_logs();
1551 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1552
1553 _young_list->reset_sampled_info();
1554 // At this point there should be no regions in the
1555 // entire heap tagged as young.
1556 assert(check_young_list_empty(true /* check_heap */),
1557 "young list should be empty at this point");
1558
1559 // Update the number of full collections that have been completed.
1560 increment_old_marking_cycles_completed(false /* concurrent */);
1561
1562 _hrm.verify_optional();
1563 verify_region_sets_optional();
1564
1565 verify_after_gc();
1566
1567 // Clear the previous marking bitmap, if needed for bitmap verification.
1568 // Note we cannot do this when we clear the next marking bitmap in
1569 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1570 // objects marked during a full GC against the previous bitmap.
1571 // But we need to clear it before calling check_bitmaps below since
1572 // the full GC has compacted objects and updated TAMS but not updated
1573 // the prev bitmap.
1574 if (G1VerifyBitmaps) {
1575 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1576 }
1577 check_bitmaps("Full GC End");
1578
1579 // Start a new incremental collection set for the next pause
1580 assert(g1_policy()->collection_set() == NULL, "must be");
1581 g1_policy()->start_incremental_cset_building();
1582
1583 clear_cset_fast_test();
1584
1585 _allocator->init_mutator_alloc_region();
1586
1587 g1_policy()->record_full_collection_end();
1588
1589 if (G1Log::fine()) {
1590 g1_policy()->print_heap_transition();
1591 }
1592
1593 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1594 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1595 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1596 // before any GC notifications are raised.
1597 g1mm()->update_sizes();
1598
1599 gc_epilogue(true);
1600 }
1601
1602 if (G1Log::finer()) {
1603 g1_policy()->print_detailed_heap_transition(true /* full */);
1604 }
1605
1606 print_heap_after_gc();
1607 trace_heap_after_gc(gc_tracer);
1608
1609 post_full_gc_dump(gc_timer);
1610
1611 gc_timer->register_gc_end();
1612 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1613 }
1614
1615 return true;
1616 }
1617
1618 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1619 // do_collection() will return whether it succeeded in performing
1620 // the GC. Currently, there is no facility on the
1621 // do_full_collection() API to notify the caller than the collection
1622 // did not succeed (e.g., because it was locked out by the GC
1623 // locker). So, right now, we'll ignore the return value.
1624 bool dummy = do_collection(true, /* explicit_gc */
1625 clear_all_soft_refs,
1626 0 /* word_size */);
1627 }
1628
1629 // This code is mostly copied from TenuredGeneration.
1630 void
1631 G1CollectedHeap::
1632 resize_if_necessary_after_full_collection(size_t word_size) {
1633 // Include the current allocation, if any, and bytes that will be
1634 // pre-allocated to support collections, as "used".
1635 const size_t used_after_gc = used();
1636 const size_t capacity_after_gc = capacity();
1637 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1638
1639 // This is enforced in arguments.cpp.
1640 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1641 "otherwise the code below doesn't make sense");
1642
1643 // We don't have floating point command-line arguments
1644 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1645 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1646 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1647 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1648
1649 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1650 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1651
1652 // We have to be careful here as these two calculations can overflow
1653 // 32-bit size_t's.
1654 double used_after_gc_d = (double) used_after_gc;
1655 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1656 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1657
1658 // Let's make sure that they are both under the max heap size, which
1659 // by default will make them fit into a size_t.
1660 double desired_capacity_upper_bound = (double) max_heap_size;
1661 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1662 desired_capacity_upper_bound);
1663 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1664 desired_capacity_upper_bound);
1665
1666 // We can now safely turn them into size_t's.
1667 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1668 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1669
1670 // This assert only makes sense here, before we adjust them
1671 // with respect to the min and max heap size.
1672 assert(minimum_desired_capacity <= maximum_desired_capacity,
1673 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1674 "maximum_desired_capacity = "SIZE_FORMAT,
1675 minimum_desired_capacity, maximum_desired_capacity));
1676
1677 // Should not be greater than the heap max size. No need to adjust
1678 // it with respect to the heap min size as it's a lower bound (i.e.,
1679 // we'll try to make the capacity larger than it, not smaller).
1680 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1681 // Should not be less than the heap min size. No need to adjust it
1682 // with respect to the heap max size as it's an upper bound (i.e.,
1683 // we'll try to make the capacity smaller than it, not greater).
1684 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1685
1686 if (capacity_after_gc < minimum_desired_capacity) {
1687 // Don't expand unless it's significant
1688 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1689 ergo_verbose4(ErgoHeapSizing,
1690 "attempt heap expansion",
1691 ergo_format_reason("capacity lower than "
1692 "min desired capacity after Full GC")
1693 ergo_format_byte("capacity")
1694 ergo_format_byte("occupancy")
1695 ergo_format_byte_perc("min desired capacity"),
1696 capacity_after_gc, used_after_gc,
1697 minimum_desired_capacity, (double) MinHeapFreeRatio);
1698 expand(expand_bytes);
1699
1700 // No expansion, now see if we want to shrink
1701 } else if (capacity_after_gc > maximum_desired_capacity) {
1702 // Capacity too large, compute shrinking size
1703 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1704 ergo_verbose4(ErgoHeapSizing,
1705 "attempt heap shrinking",
1706 ergo_format_reason("capacity higher than "
1707 "max desired capacity after Full GC")
1708 ergo_format_byte("capacity")
1709 ergo_format_byte("occupancy")
1710 ergo_format_byte_perc("max desired capacity"),
1711 capacity_after_gc, used_after_gc,
1712 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1713 shrink(shrink_bytes);
1714 }
1715 }
1716
1717
1718 HeapWord*
1719 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1720 AllocationContext_t context,
1721 bool* succeeded) {
1722 assert_at_safepoint(true /* should_be_vm_thread */);
1723
1724 *succeeded = true;
1725 // Let's attempt the allocation first.
1726 HeapWord* result =
1727 attempt_allocation_at_safepoint(word_size,
1728 context,
1729 false /* expect_null_mutator_alloc_region */);
1730 if (result != NULL) {
1731 assert(*succeeded, "sanity");
1732 return result;
1733 }
1734
1735 // In a G1 heap, we're supposed to keep allocation from failing by
1736 // incremental pauses. Therefore, at least for now, we'll favor
1737 // expansion over collection. (This might change in the future if we can
1738 // do something smarter than full collection to satisfy a failed alloc.)
1739 result = expand_and_allocate(word_size, context);
1740 if (result != NULL) {
1741 assert(*succeeded, "sanity");
1742 return result;
1743 }
1744
1745 // Expansion didn't work, we'll try to do a Full GC.
1746 bool gc_succeeded = do_collection(false, /* explicit_gc */
1747 false, /* clear_all_soft_refs */
1748 word_size);
1749 if (!gc_succeeded) {
1750 *succeeded = false;
1751 return NULL;
1752 }
1753
1754 // Retry the allocation
1755 result = attempt_allocation_at_safepoint(word_size,
1756 context,
1757 true /* expect_null_mutator_alloc_region */);
1758 if (result != NULL) {
1759 assert(*succeeded, "sanity");
1760 return result;
1761 }
1762
1763 // Then, try a Full GC that will collect all soft references.
1764 gc_succeeded = do_collection(false, /* explicit_gc */
1765 true, /* clear_all_soft_refs */
1766 word_size);
1767 if (!gc_succeeded) {
1768 *succeeded = false;
1769 return NULL;
1770 }
1771
1772 // Retry the allocation once more
1773 result = attempt_allocation_at_safepoint(word_size,
1774 context,
1775 true /* expect_null_mutator_alloc_region */);
1776 if (result != NULL) {
1777 assert(*succeeded, "sanity");
1778 return result;
1779 }
1780
1781 assert(!collector_policy()->should_clear_all_soft_refs(),
1782 "Flag should have been handled and cleared prior to this point");
1783
1784 // What else? We might try synchronous finalization later. If the total
1785 // space available is large enough for the allocation, then a more
1786 // complete compaction phase than we've tried so far might be
1787 // appropriate.
1788 assert(*succeeded, "sanity");
1789 return NULL;
1790 }
1791
1792 // Attempting to expand the heap sufficiently
1793 // to support an allocation of the given "word_size". If
1794 // successful, perform the allocation and return the address of the
1795 // allocated block, or else "NULL".
1796
1797 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1798 assert_at_safepoint(true /* should_be_vm_thread */);
1799
1800 verify_region_sets_optional();
1801
1802 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1803 ergo_verbose1(ErgoHeapSizing,
1804 "attempt heap expansion",
1805 ergo_format_reason("allocation request failed")
1806 ergo_format_byte("allocation request"),
1807 word_size * HeapWordSize);
1808 if (expand(expand_bytes)) {
1809 _hrm.verify_optional();
1810 verify_region_sets_optional();
1811 return attempt_allocation_at_safepoint(word_size,
1812 context,
1813 false /* expect_null_mutator_alloc_region */);
1814 }
1815 return NULL;
1816 }
1817
1818 bool G1CollectedHeap::expand(size_t expand_bytes) {
1819 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1820 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1821 HeapRegion::GrainBytes);
1822 ergo_verbose2(ErgoHeapSizing,
1823 "expand the heap",
1824 ergo_format_byte("requested expansion amount")
1825 ergo_format_byte("attempted expansion amount"),
1826 expand_bytes, aligned_expand_bytes);
1827
1828 if (is_maximal_no_gc()) {
1829 ergo_verbose0(ErgoHeapSizing,
1830 "did not expand the heap",
1831 ergo_format_reason("heap already fully expanded"));
1832 return false;
1833 }
1834
1835 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1836 assert(regions_to_expand > 0, "Must expand by at least one region");
1837
1838 uint expanded_by = _hrm.expand_by(regions_to_expand);
1839
1840 if (expanded_by > 0) {
1841 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1842 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1843 g1_policy()->record_new_heap_size(num_regions());
1844 } else {
1845 ergo_verbose0(ErgoHeapSizing,
1846 "did not expand the heap",
1847 ergo_format_reason("heap expansion operation failed"));
1848 // The expansion of the virtual storage space was unsuccessful.
1849 // Let's see if it was because we ran out of swap.
1850 if (G1ExitOnExpansionFailure &&
1851 _hrm.available() >= regions_to_expand) {
1852 // We had head room...
1853 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1854 }
1855 }
1856 return regions_to_expand > 0;
1857 }
1858
1859 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1860 size_t aligned_shrink_bytes =
1861 ReservedSpace::page_align_size_down(shrink_bytes);
1862 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863 HeapRegion::GrainBytes);
1864 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865
1866 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1867 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1868
1869 ergo_verbose3(ErgoHeapSizing,
1870 "shrink the heap",
1871 ergo_format_byte("requested shrinking amount")
1872 ergo_format_byte("aligned shrinking amount")
1873 ergo_format_byte("attempted shrinking amount"),
1874 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1875 if (num_regions_removed > 0) {
1876 g1_policy()->record_new_heap_size(num_regions());
1877 } else {
1878 ergo_verbose0(ErgoHeapSizing,
1879 "did not shrink the heap",
1880 ergo_format_reason("heap shrinking operation failed"));
1881 }
1882 }
1883
1884 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1885 verify_region_sets_optional();
1886
1887 // We should only reach here at the end of a Full GC which means we
1888 // should not not be holding to any GC alloc regions. The method
1889 // below will make sure of that and do any remaining clean up.
1890 _allocator->abandon_gc_alloc_regions();
1891
1892 // Instead of tearing down / rebuilding the free lists here, we
1893 // could instead use the remove_all_pending() method on free_list to
1894 // remove only the ones that we need to remove.
1895 tear_down_region_sets(true /* free_list_only */);
1896 shrink_helper(shrink_bytes);
1897 rebuild_region_sets(true /* free_list_only */);
1898
1899 _hrm.verify_optional();
1900 verify_region_sets_optional();
1901 }
1902
1903 // Public methods.
1904
1905 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1906 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1907 #endif // _MSC_VER
1908
1909
1910 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1911 CollectedHeap(),
1912 _g1_policy(policy_),
1913 _dirty_card_queue_set(false),
1914 _into_cset_dirty_card_queue_set(false),
1915 _is_alive_closure_cm(this),
1916 _is_alive_closure_stw(this),
1917 _ref_processor_cm(NULL),
1918 _ref_processor_stw(NULL),
1919 _bot_shared(NULL),
1920 _evac_failure_scan_stack(NULL),
1921 _cg1r(NULL),
1922 _g1mm(NULL),
1923 _refine_cte_cl(NULL),
1924 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1925 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1926 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1927 _humongous_reclaim_candidates(),
1928 _has_humongous_reclaim_candidates(false),
1929 _archive_allocator(NULL),
1930 _free_regions_coming(false),
1931 _young_list(new YoungList(this)),
1932 _gc_time_stamp(0),
1933 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1934 _old_plab_stats(OldPLABSize, PLABWeight),
1935 _expand_heap_after_alloc_failure(true),
1936 _surviving_young_words(NULL),
1937 _old_marking_cycles_started(0),
1938 _old_marking_cycles_completed(0),
1939 _heap_summary_sent(false),
1940 _in_cset_fast_test(),
1941 _dirty_cards_region_list(NULL),
1942 _worker_cset_start_region(NULL),
1943 _worker_cset_start_region_time_stamp(NULL),
1944 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1945 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1946 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1947 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1948
1949 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1950 /* are_GC_task_threads */true,
1951 /* are_ConcurrentGC_threads */false);
1952 _workers->initialize_workers();
1953
1954 _allocator = G1Allocator::create_allocator(this);
1955 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1956
1957 // Override the default _filler_array_max_size so that no humongous filler
1958 // objects are created.
1959 _filler_array_max_size = _humongous_object_threshold_in_words;
1960
1961 uint n_queues = ParallelGCThreads;
1962 _task_queues = new RefToScanQueueSet(n_queues);
1963
1964 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1965 assert(n_rem_sets > 0, "Invariant.");
1966
1967 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1968 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1969 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1970
1971 for (uint i = 0; i < n_queues; i++) {
1972 RefToScanQueue* q = new RefToScanQueue();
1973 q->initialize();
1974 _task_queues->register_queue(i, q);
1975 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1976 }
1977 clear_cset_start_regions();
1978
1979 // Initialize the G1EvacuationFailureALot counters and flags.
1980 NOT_PRODUCT(reset_evacuation_should_fail();)
1981
1982 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1983 }
1984
1985 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1986 size_t size,
1987 size_t translation_factor) {
1988 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1989 // Allocate a new reserved space, preferring to use large pages.
1990 ReservedSpace rs(size, preferred_page_size);
1991 G1RegionToSpaceMapper* result =
1992 G1RegionToSpaceMapper::create_mapper(rs,
1993 size,
1994 rs.alignment(),
1995 HeapRegion::GrainBytes,
1996 translation_factor,
1997 mtGC);
1998 if (TracePageSizes) {
1999 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2000 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2001 }
2002 return result;
2003 }
2004
2005 jint G1CollectedHeap::initialize() {
2006 CollectedHeap::pre_initialize();
2007 os::enable_vtime();
2008
2009 G1Log::init();
2010
2011 // Necessary to satisfy locking discipline assertions.
2012
2013 MutexLocker x(Heap_lock);
2014
2015 // We have to initialize the printer before committing the heap, as
2016 // it will be used then.
2017 _hr_printer.set_active(G1PrintHeapRegions);
2018
2019 // While there are no constraints in the GC code that HeapWordSize
2020 // be any particular value, there are multiple other areas in the
2021 // system which believe this to be true (e.g. oop->object_size in some
2022 // cases incorrectly returns the size in wordSize units rather than
2023 // HeapWordSize).
2024 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2025
2026 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2027 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2028 size_t heap_alignment = collector_policy()->heap_alignment();
2029
2030 // Ensure that the sizes are properly aligned.
2031 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2032 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2033 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2034
2035 _refine_cte_cl = new RefineCardTableEntryClosure();
2036
2037 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2038
2039 // Reserve the maximum.
2040
2041 // When compressed oops are enabled, the preferred heap base
2042 // is calculated by subtracting the requested size from the
2043 // 32Gb boundary and using the result as the base address for
2044 // heap reservation. If the requested size is not aligned to
2045 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2046 // into the ReservedHeapSpace constructor) then the actual
2047 // base of the reserved heap may end up differing from the
2048 // address that was requested (i.e. the preferred heap base).
2049 // If this happens then we could end up using a non-optimal
2050 // compressed oops mode.
2051
2052 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2053 heap_alignment);
2054
2055 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2056
2057 // Create the barrier set for the entire reserved region.
2058 G1SATBCardTableLoggingModRefBS* bs
2059 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2060 bs->initialize();
2061 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2062 set_barrier_set(bs);
2063
2064 // Also create a G1 rem set.
2065 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2066
2067 // Carve out the G1 part of the heap.
2068
2069 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2070 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2071 G1RegionToSpaceMapper* heap_storage =
2072 G1RegionToSpaceMapper::create_mapper(g1_rs,
2073 g1_rs.size(),
2074 page_size,
2075 HeapRegion::GrainBytes,
2076 1,
2077 mtJavaHeap);
2078 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2079 max_byte_size, page_size,
2080 heap_rs.base(),
2081 heap_rs.size());
2082 heap_storage->set_mapping_changed_listener(&_listener);
2083
2084 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2085 G1RegionToSpaceMapper* bot_storage =
2086 create_aux_memory_mapper("Block offset table",
2087 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2088 G1BlockOffsetSharedArray::heap_map_factor());
2089
2090 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2091 G1RegionToSpaceMapper* cardtable_storage =
2092 create_aux_memory_mapper("Card table",
2093 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2094 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2095
2096 G1RegionToSpaceMapper* card_counts_storage =
2097 create_aux_memory_mapper("Card counts table",
2098 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2099 G1CardCounts::heap_map_factor());
2100
2101 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2102 G1RegionToSpaceMapper* prev_bitmap_storage =
2103 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2104 G1RegionToSpaceMapper* next_bitmap_storage =
2105 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2106
2107 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2108 g1_barrier_set()->initialize(cardtable_storage);
2109 // Do later initialization work for concurrent refinement.
2110 _cg1r->init(card_counts_storage);
2111
2112 // 6843694 - ensure that the maximum region index can fit
2113 // in the remembered set structures.
2114 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2115 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2116
2117 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2118 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2119 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2120 "too many cards per region");
2121
2122 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2123
2124 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2125
2126 {
2127 HeapWord* start = _hrm.reserved().start();
2128 HeapWord* end = _hrm.reserved().end();
2129 size_t granularity = HeapRegion::GrainBytes;
2130
2131 _in_cset_fast_test.initialize(start, end, granularity);
2132 _humongous_reclaim_candidates.initialize(start, end, granularity);
2133 }
2134
2135 // Create the ConcurrentMark data structure and thread.
2136 // (Must do this late, so that "max_regions" is defined.)
2137 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2138 if (_cm == NULL || !_cm->completed_initialization()) {
2139 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2140 return JNI_ENOMEM;
2141 }
2142 _cmThread = _cm->cmThread();
2143
2144 // Initialize the from_card cache structure of HeapRegionRemSet.
2145 HeapRegionRemSet::init_heap(max_regions());
2146
2147 // Now expand into the initial heap size.
2148 if (!expand(init_byte_size)) {
2149 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2150 return JNI_ENOMEM;
2151 }
2152
2153 // Perform any initialization actions delegated to the policy.
2154 g1_policy()->init();
2155
2156 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2157 SATB_Q_FL_lock,
2158 G1SATBProcessCompletedThreshold,
2159 Shared_SATB_Q_lock);
2160
2161 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2162 DirtyCardQ_CBL_mon,
2163 DirtyCardQ_FL_lock,
2164 concurrent_g1_refine()->yellow_zone(),
2165 concurrent_g1_refine()->red_zone(),
2166 Shared_DirtyCardQ_lock);
2167
2168 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2169 DirtyCardQ_CBL_mon,
2170 DirtyCardQ_FL_lock,
2171 -1, // never trigger processing
2172 -1, // no limit on length
2173 Shared_DirtyCardQ_lock,
2174 &JavaThread::dirty_card_queue_set());
2175
2176 // Initialize the card queue set used to hold cards containing
2177 // references into the collection set.
2178 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2179 DirtyCardQ_CBL_mon,
2180 DirtyCardQ_FL_lock,
2181 -1, // never trigger processing
2182 -1, // no limit on length
2183 Shared_DirtyCardQ_lock,
2184 &JavaThread::dirty_card_queue_set());
2185
2186 // Here we allocate the dummy HeapRegion that is required by the
2187 // G1AllocRegion class.
2188 HeapRegion* dummy_region = _hrm.get_dummy_region();
2189
2190 // We'll re-use the same region whether the alloc region will
2191 // require BOT updates or not and, if it doesn't, then a non-young
2192 // region will complain that it cannot support allocations without
2193 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2194 dummy_region->set_eden();
2195 // Make sure it's full.
2196 dummy_region->set_top(dummy_region->end());
2197 G1AllocRegion::setup(this, dummy_region);
2198
2199 _allocator->init_mutator_alloc_region();
2200
2201 // Do create of the monitoring and management support so that
2202 // values in the heap have been properly initialized.
2203 _g1mm = new G1MonitoringSupport(this);
2204
2205 G1StringDedup::initialize();
2206
2207 return JNI_OK;
2208 }
2209
2210 void G1CollectedHeap::stop() {
2211 // Stop all concurrent threads. We do this to make sure these threads
2212 // do not continue to execute and access resources (e.g. gclog_or_tty)
2213 // that are destroyed during shutdown.
2214 _cg1r->stop();
2215 _cmThread->stop();
2216 if (G1StringDedup::is_enabled()) {
2217 G1StringDedup::stop();
2218 }
2219 }
2220
2221 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2222 return HeapRegion::max_region_size();
2223 }
2224
2225 void G1CollectedHeap::post_initialize() {
2226 CollectedHeap::post_initialize();
2227 ref_processing_init();
2228 }
2229
2230 void G1CollectedHeap::ref_processing_init() {
2231 // Reference processing in G1 currently works as follows:
2232 //
2233 // * There are two reference processor instances. One is
2234 // used to record and process discovered references
2235 // during concurrent marking; the other is used to
2236 // record and process references during STW pauses
2237 // (both full and incremental).
2238 // * Both ref processors need to 'span' the entire heap as
2239 // the regions in the collection set may be dotted around.
2240 //
2241 // * For the concurrent marking ref processor:
2242 // * Reference discovery is enabled at initial marking.
2243 // * Reference discovery is disabled and the discovered
2244 // references processed etc during remarking.
2245 // * Reference discovery is MT (see below).
2246 // * Reference discovery requires a barrier (see below).
2247 // * Reference processing may or may not be MT
2248 // (depending on the value of ParallelRefProcEnabled
2249 // and ParallelGCThreads).
2250 // * A full GC disables reference discovery by the CM
2251 // ref processor and abandons any entries on it's
2252 // discovered lists.
2253 //
2254 // * For the STW processor:
2255 // * Non MT discovery is enabled at the start of a full GC.
2256 // * Processing and enqueueing during a full GC is non-MT.
2257 // * During a full GC, references are processed after marking.
2258 //
2259 // * Discovery (may or may not be MT) is enabled at the start
2260 // of an incremental evacuation pause.
2261 // * References are processed near the end of a STW evacuation pause.
2262 // * For both types of GC:
2263 // * Discovery is atomic - i.e. not concurrent.
2264 // * Reference discovery will not need a barrier.
2265
2266 MemRegion mr = reserved_region();
2267
2268 // Concurrent Mark ref processor
2269 _ref_processor_cm =
2270 new ReferenceProcessor(mr, // span
2271 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2272 // mt processing
2273 ParallelGCThreads,
2274 // degree of mt processing
2275 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2276 // mt discovery
2277 MAX2(ParallelGCThreads, ConcGCThreads),
2278 // degree of mt discovery
2279 false,
2280 // Reference discovery is not atomic
2281 &_is_alive_closure_cm);
2282 // is alive closure
2283 // (for efficiency/performance)
2284
2285 // STW ref processor
2286 _ref_processor_stw =
2287 new ReferenceProcessor(mr, // span
2288 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2289 // mt processing
2290 ParallelGCThreads,
2291 // degree of mt processing
2292 (ParallelGCThreads > 1),
2293 // mt discovery
2294 ParallelGCThreads,
2295 // degree of mt discovery
2296 true,
2297 // Reference discovery is atomic
2298 &_is_alive_closure_stw);
2299 // is alive closure
2300 // (for efficiency/performance)
2301 }
2302
2303 size_t G1CollectedHeap::capacity() const {
2304 return _hrm.length() * HeapRegion::GrainBytes;
2305 }
2306
2307 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2308 assert(!hr->is_continues_humongous(), "pre-condition");
2309 hr->reset_gc_time_stamp();
2310 if (hr->is_starts_humongous()) {
2311 uint first_index = hr->hrm_index() + 1;
2312 uint last_index = hr->last_hc_index();
2313 for (uint i = first_index; i < last_index; i += 1) {
2314 HeapRegion* chr = region_at(i);
2315 assert(chr->is_continues_humongous(), "sanity");
2316 chr->reset_gc_time_stamp();
2317 }
2318 }
2319 }
2320
2321 #ifndef PRODUCT
2322
2323 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2324 private:
2325 unsigned _gc_time_stamp;
2326 bool _failures;
2327
2328 public:
2329 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2330 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2331
2332 virtual bool doHeapRegion(HeapRegion* hr) {
2333 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2334 if (_gc_time_stamp != region_gc_time_stamp) {
2335 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2336 "expected %d", HR_FORMAT_PARAMS(hr),
2337 region_gc_time_stamp, _gc_time_stamp);
2338 _failures = true;
2339 }
2340 return false;
2341 }
2342
2343 bool failures() { return _failures; }
2344 };
2345
2346 void G1CollectedHeap::check_gc_time_stamps() {
2347 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2348 heap_region_iterate(&cl);
2349 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2350 }
2351 #endif // PRODUCT
2352
2353 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2354 DirtyCardQueue* into_cset_dcq,
2355 bool concurrent,
2356 uint worker_i) {
2357 // Clean cards in the hot card cache
2358 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2359 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2360
2361 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2362 size_t n_completed_buffers = 0;
2363 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2364 n_completed_buffers++;
2365 }
2366 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2367 dcqs.clear_n_completed_buffers();
2368 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2369 }
2370
2371
2372 // Computes the sum of the storage used by the various regions.
2373 size_t G1CollectedHeap::used() const {
2374 size_t result = _allocator->used();
2375 if (_archive_allocator != NULL) {
2376 result += _archive_allocator->used();
2377 }
2378 return result;
2379 }
2380
2381 size_t G1CollectedHeap::used_unlocked() const {
2382 return _allocator->used_unlocked();
2383 }
2384
2385 class SumUsedClosure: public HeapRegionClosure {
2386 size_t _used;
2387 public:
2388 SumUsedClosure() : _used(0) {}
2389 bool doHeapRegion(HeapRegion* r) {
2390 if (!r->is_continues_humongous()) {
2391 _used += r->used();
2392 }
2393 return false;
2394 }
2395 size_t result() { return _used; }
2396 };
2397
2398 size_t G1CollectedHeap::recalculate_used() const {
2399 double recalculate_used_start = os::elapsedTime();
2400
2401 SumUsedClosure blk;
2402 heap_region_iterate(&blk);
2403
2404 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2405 return blk.result();
2406 }
2407
2408 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2409 switch (cause) {
2410 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2411 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2412 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2413 case GCCause::_g1_humongous_allocation: return true;
2414 case GCCause::_update_allocation_context_stats_inc: return true;
2415 case GCCause::_wb_conc_mark: return true;
2416 default: return false;
2417 }
2418 }
2419
2420 #ifndef PRODUCT
2421 void G1CollectedHeap::allocate_dummy_regions() {
2422 // Let's fill up most of the region
2423 size_t word_size = HeapRegion::GrainWords - 1024;
2424 // And as a result the region we'll allocate will be humongous.
2425 guarantee(is_humongous(word_size), "sanity");
2426
2427 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2428 // Let's use the existing mechanism for the allocation
2429 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2430 AllocationContext::system());
2431 if (dummy_obj != NULL) {
2432 MemRegion mr(dummy_obj, word_size);
2433 CollectedHeap::fill_with_object(mr);
2434 } else {
2435 // If we can't allocate once, we probably cannot allocate
2436 // again. Let's get out of the loop.
2437 break;
2438 }
2439 }
2440 }
2441 #endif // !PRODUCT
2442
2443 void G1CollectedHeap::increment_old_marking_cycles_started() {
2444 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2445 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2446 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2447 _old_marking_cycles_started, _old_marking_cycles_completed));
2448
2449 _old_marking_cycles_started++;
2450 }
2451
2452 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2453 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2454
2455 // We assume that if concurrent == true, then the caller is a
2456 // concurrent thread that was joined the Suspendible Thread
2457 // Set. If there's ever a cheap way to check this, we should add an
2458 // assert here.
2459
2460 // Given that this method is called at the end of a Full GC or of a
2461 // concurrent cycle, and those can be nested (i.e., a Full GC can
2462 // interrupt a concurrent cycle), the number of full collections
2463 // completed should be either one (in the case where there was no
2464 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2465 // behind the number of full collections started.
2466
2467 // This is the case for the inner caller, i.e. a Full GC.
2468 assert(concurrent ||
2469 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2470 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2471 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2472 "is inconsistent with _old_marking_cycles_completed = %u",
2473 _old_marking_cycles_started, _old_marking_cycles_completed));
2474
2475 // This is the case for the outer caller, i.e. the concurrent cycle.
2476 assert(!concurrent ||
2477 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2478 err_msg("for outer caller (concurrent cycle): "
2479 "_old_marking_cycles_started = %u "
2480 "is inconsistent with _old_marking_cycles_completed = %u",
2481 _old_marking_cycles_started, _old_marking_cycles_completed));
2482
2483 _old_marking_cycles_completed += 1;
2484
2485 // We need to clear the "in_progress" flag in the CM thread before
2486 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2487 // is set) so that if a waiter requests another System.gc() it doesn't
2488 // incorrectly see that a marking cycle is still in progress.
2489 if (concurrent) {
2490 _cmThread->clear_in_progress();
2491 }
2492
2493 // This notify_all() will ensure that a thread that called
2494 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2495 // and it's waiting for a full GC to finish will be woken up. It is
2496 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2497 FullGCCount_lock->notify_all();
2498 }
2499
2500 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2501 collector_state()->set_concurrent_cycle_started(true);
2502 _gc_timer_cm->register_gc_start(start_time);
2503
2504 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2505 trace_heap_before_gc(_gc_tracer_cm);
2506 }
2507
2508 void G1CollectedHeap::register_concurrent_cycle_end() {
2509 if (collector_state()->concurrent_cycle_started()) {
2510 if (_cm->has_aborted()) {
2511 _gc_tracer_cm->report_concurrent_mode_failure();
2512 }
2513
2514 _gc_timer_cm->register_gc_end();
2515 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2516
2517 // Clear state variables to prepare for the next concurrent cycle.
2518 collector_state()->set_concurrent_cycle_started(false);
2519 _heap_summary_sent = false;
2520 }
2521 }
2522
2523 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2524 if (collector_state()->concurrent_cycle_started()) {
2525 // This function can be called when:
2526 // the cleanup pause is run
2527 // the concurrent cycle is aborted before the cleanup pause.
2528 // the concurrent cycle is aborted after the cleanup pause,
2529 // but before the concurrent cycle end has been registered.
2530 // Make sure that we only send the heap information once.
2531 if (!_heap_summary_sent) {
2532 trace_heap_after_gc(_gc_tracer_cm);
2533 _heap_summary_sent = true;
2534 }
2535 }
2536 }
2537
2538 void G1CollectedHeap::collect(GCCause::Cause cause) {
2539 assert_heap_not_locked();
2540
2541 uint gc_count_before;
2542 uint old_marking_count_before;
2543 uint full_gc_count_before;
2544 bool retry_gc;
2545
2546 do {
2547 retry_gc = false;
2548
2549 {
2550 MutexLocker ml(Heap_lock);
2551
2552 // Read the GC count while holding the Heap_lock
2553 gc_count_before = total_collections();
2554 full_gc_count_before = total_full_collections();
2555 old_marking_count_before = _old_marking_cycles_started;
2556 }
2557
2558 if (should_do_concurrent_full_gc(cause)) {
2559 // Schedule an initial-mark evacuation pause that will start a
2560 // concurrent cycle. We're setting word_size to 0 which means that
2561 // we are not requesting a post-GC allocation.
2562 VM_G1IncCollectionPause op(gc_count_before,
2563 0, /* word_size */
2564 true, /* should_initiate_conc_mark */
2565 g1_policy()->max_pause_time_ms(),
2566 cause);
2567 op.set_allocation_context(AllocationContext::current());
2568
2569 VMThread::execute(&op);
2570 if (!op.pause_succeeded()) {
2571 if (old_marking_count_before == _old_marking_cycles_started) {
2572 retry_gc = op.should_retry_gc();
2573 } else {
2574 // A Full GC happened while we were trying to schedule the
2575 // initial-mark GC. No point in starting a new cycle given
2576 // that the whole heap was collected anyway.
2577 }
2578
2579 if (retry_gc) {
2580 if (GC_locker::is_active_and_needs_gc()) {
2581 GC_locker::stall_until_clear();
2582 }
2583 }
2584 }
2585 } else {
2586 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2587 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2588
2589 // Schedule a standard evacuation pause. We're setting word_size
2590 // to 0 which means that we are not requesting a post-GC allocation.
2591 VM_G1IncCollectionPause op(gc_count_before,
2592 0, /* word_size */
2593 false, /* should_initiate_conc_mark */
2594 g1_policy()->max_pause_time_ms(),
2595 cause);
2596 VMThread::execute(&op);
2597 } else {
2598 // Schedule a Full GC.
2599 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2600 VMThread::execute(&op);
2601 }
2602 }
2603 } while (retry_gc);
2604 }
2605
2606 bool G1CollectedHeap::is_in(const void* p) const {
2607 if (_hrm.reserved().contains(p)) {
2608 // Given that we know that p is in the reserved space,
2609 // heap_region_containing_raw() should successfully
2610 // return the containing region.
2611 HeapRegion* hr = heap_region_containing_raw(p);
2612 return hr->is_in(p);
2613 } else {
2614 return false;
2615 }
2616 }
2617
2618 #ifdef ASSERT
2619 bool G1CollectedHeap::is_in_exact(const void* p) const {
2620 bool contains = reserved_region().contains(p);
2621 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2622 if (contains && available) {
2623 return true;
2624 } else {
2625 return false;
2626 }
2627 }
2628 #endif
2629
2630 // Iteration functions.
2631
2632 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2633
2634 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2635 ExtendedOopClosure* _cl;
2636 public:
2637 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2638 bool doHeapRegion(HeapRegion* r) {
2639 if (!r->is_continues_humongous()) {
2640 r->oop_iterate(_cl);
2641 }
2642 return false;
2643 }
2644 };
2645
2646 // Iterates an ObjectClosure over all objects within a HeapRegion.
2647
2648 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2649 ObjectClosure* _cl;
2650 public:
2651 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2652 bool doHeapRegion(HeapRegion* r) {
2653 if (!r->is_continues_humongous()) {
2654 r->object_iterate(_cl);
2655 }
2656 return false;
2657 }
2658 };
2659
2660 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2661 IterateObjectClosureRegionClosure blk(cl);
2662 heap_region_iterate(&blk);
2663 }
2664
2665 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2666 _hrm.iterate(cl);
2667 }
2668
2669 void
2670 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2671 uint worker_id,
2672 HeapRegionClaimer *hrclaimer,
2673 bool concurrent) const {
2674 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2675 }
2676
2677 // Clear the cached CSet starting regions and (more importantly)
2678 // the time stamps. Called when we reset the GC time stamp.
2679 void G1CollectedHeap::clear_cset_start_regions() {
2680 assert(_worker_cset_start_region != NULL, "sanity");
2681 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2682
2683 for (uint i = 0; i < ParallelGCThreads; i++) {
2684 _worker_cset_start_region[i] = NULL;
2685 _worker_cset_start_region_time_stamp[i] = 0;
2686 }
2687 }
2688
2689 // Given the id of a worker, obtain or calculate a suitable
2690 // starting region for iterating over the current collection set.
2691 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2692 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2693
2694 HeapRegion* result = NULL;
2695 unsigned gc_time_stamp = get_gc_time_stamp();
2696
2697 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2698 // Cached starting region for current worker was set
2699 // during the current pause - so it's valid.
2700 // Note: the cached starting heap region may be NULL
2701 // (when the collection set is empty).
2702 result = _worker_cset_start_region[worker_i];
2703 assert(result == NULL || result->in_collection_set(), "sanity");
2704 return result;
2705 }
2706
2707 // The cached entry was not valid so let's calculate
2708 // a suitable starting heap region for this worker.
2709
2710 // We want the parallel threads to start their collection
2711 // set iteration at different collection set regions to
2712 // avoid contention.
2713 // If we have:
2714 // n collection set regions
2715 // p threads
2716 // Then thread t will start at region floor ((t * n) / p)
2717
2718 result = g1_policy()->collection_set();
2719 uint cs_size = g1_policy()->cset_region_length();
2720 uint active_workers = workers()->active_workers();
2721
2722 uint end_ind = (cs_size * worker_i) / active_workers;
2723 uint start_ind = 0;
2724
2725 if (worker_i > 0 &&
2726 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2727 // Previous workers starting region is valid
2728 // so let's iterate from there
2729 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2730 result = _worker_cset_start_region[worker_i - 1];
2731 }
2732
2733 for (uint i = start_ind; i < end_ind; i++) {
2734 result = result->next_in_collection_set();
2735 }
2736
2737 // Note: the calculated starting heap region may be NULL
2738 // (when the collection set is empty).
2739 assert(result == NULL || result->in_collection_set(), "sanity");
2740 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2741 "should be updated only once per pause");
2742 _worker_cset_start_region[worker_i] = result;
2743 OrderAccess::storestore();
2744 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2745 return result;
2746 }
2747
2748 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2749 HeapRegion* r = g1_policy()->collection_set();
2750 while (r != NULL) {
2751 HeapRegion* next = r->next_in_collection_set();
2752 if (cl->doHeapRegion(r)) {
2753 cl->incomplete();
2754 return;
2755 }
2756 r = next;
2757 }
2758 }
2759
2760 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2761 HeapRegionClosure *cl) {
2762 if (r == NULL) {
2763 // The CSet is empty so there's nothing to do.
2764 return;
2765 }
2766
2767 assert(r->in_collection_set(),
2768 "Start region must be a member of the collection set.");
2769 HeapRegion* cur = r;
2770 while (cur != NULL) {
2771 HeapRegion* next = cur->next_in_collection_set();
2772 if (cl->doHeapRegion(cur) && false) {
2773 cl->incomplete();
2774 return;
2775 }
2776 cur = next;
2777 }
2778 cur = g1_policy()->collection_set();
2779 while (cur != r) {
2780 HeapRegion* next = cur->next_in_collection_set();
2781 if (cl->doHeapRegion(cur) && false) {
2782 cl->incomplete();
2783 return;
2784 }
2785 cur = next;
2786 }
2787 }
2788
2789 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2790 HeapRegion* result = _hrm.next_region_in_heap(from);
2791 while (result != NULL && result->is_pinned()) {
2792 result = _hrm.next_region_in_heap(result);
2793 }
2794 return result;
2795 }
2796
2797 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2798 HeapRegion* hr = heap_region_containing(addr);
2799 return hr->block_start(addr);
2800 }
2801
2802 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2803 HeapRegion* hr = heap_region_containing(addr);
2804 return hr->block_size(addr);
2805 }
2806
2807 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2808 HeapRegion* hr = heap_region_containing(addr);
2809 return hr->block_is_obj(addr);
2810 }
2811
2812 bool G1CollectedHeap::supports_tlab_allocation() const {
2813 return true;
2814 }
2815
2816 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2817 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2818 }
2819
2820 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2821 return young_list()->eden_used_bytes();
2822 }
2823
2824 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2825 // must be smaller than the humongous object limit.
2826 size_t G1CollectedHeap::max_tlab_size() const {
2827 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2828 }
2829
2830 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2831 // Return the remaining space in the cur alloc region, but not less than
2832 // the min TLAB size.
2833
2834 // Also, this value can be at most the humongous object threshold,
2835 // since we can't allow tlabs to grow big enough to accommodate
2836 // humongous objects.
2837
2838 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2839 size_t max_tlab = max_tlab_size() * wordSize;
2840 if (hr == NULL) {
2841 return max_tlab;
2842 } else {
2843 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2844 }
2845 }
2846
2847 size_t G1CollectedHeap::max_capacity() const {
2848 return _hrm.reserved().byte_size();
2849 }
2850
2851 jlong G1CollectedHeap::millis_since_last_gc() {
2852 // assert(false, "NYI");
2853 return 0;
2854 }
2855
2856 void G1CollectedHeap::prepare_for_verify() {
2857 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2858 ensure_parsability(false);
2859 }
2860 g1_rem_set()->prepare_for_verify();
2861 }
2862
2863 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2864 VerifyOption vo) {
2865 switch (vo) {
2866 case VerifyOption_G1UsePrevMarking:
2867 return hr->obj_allocated_since_prev_marking(obj);
2868 case VerifyOption_G1UseNextMarking:
2869 return hr->obj_allocated_since_next_marking(obj);
2870 case VerifyOption_G1UseMarkWord:
2871 return false;
2872 default:
2873 ShouldNotReachHere();
2874 }
2875 return false; // keep some compilers happy
2876 }
2877
2878 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2879 switch (vo) {
2880 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2881 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2882 case VerifyOption_G1UseMarkWord: return NULL;
2883 default: ShouldNotReachHere();
2884 }
2885 return NULL; // keep some compilers happy
2886 }
2887
2888 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2889 switch (vo) {
2890 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2891 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2892 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2893 default: ShouldNotReachHere();
2894 }
2895 return false; // keep some compilers happy
2896 }
2897
2898 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2899 switch (vo) {
2900 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2901 case VerifyOption_G1UseNextMarking: return "NTAMS";
2902 case VerifyOption_G1UseMarkWord: return "NONE";
2903 default: ShouldNotReachHere();
2904 }
2905 return NULL; // keep some compilers happy
2906 }
2907
2908 class VerifyRootsClosure: public OopClosure {
2909 private:
2910 G1CollectedHeap* _g1h;
2911 VerifyOption _vo;
2912 bool _failures;
2913 public:
2914 // _vo == UsePrevMarking -> use "prev" marking information,
2915 // _vo == UseNextMarking -> use "next" marking information,
2916 // _vo == UseMarkWord -> use mark word from object header.
2917 VerifyRootsClosure(VerifyOption vo) :
2918 _g1h(G1CollectedHeap::heap()),
2919 _vo(vo),
2920 _failures(false) { }
2921
2922 bool failures() { return _failures; }
2923
2924 template <class T> void do_oop_nv(T* p) {
2925 T heap_oop = oopDesc::load_heap_oop(p);
2926 if (!oopDesc::is_null(heap_oop)) {
2927 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2928 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2929 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2930 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2931 if (_vo == VerifyOption_G1UseMarkWord) {
2932 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2933 }
2934 obj->print_on(gclog_or_tty);
2935 _failures = true;
2936 }
2937 }
2938 }
2939
2940 void do_oop(oop* p) { do_oop_nv(p); }
2941 void do_oop(narrowOop* p) { do_oop_nv(p); }
2942 };
2943
2944 class G1VerifyCodeRootOopClosure: public OopClosure {
2945 G1CollectedHeap* _g1h;
2946 OopClosure* _root_cl;
2947 nmethod* _nm;
2948 VerifyOption _vo;
2949 bool _failures;
2950
2951 template <class T> void do_oop_work(T* p) {
2952 // First verify that this root is live
2953 _root_cl->do_oop(p);
2954
2955 if (!G1VerifyHeapRegionCodeRoots) {
2956 // We're not verifying the code roots attached to heap region.
2957 return;
2958 }
2959
2960 // Don't check the code roots during marking verification in a full GC
2961 if (_vo == VerifyOption_G1UseMarkWord) {
2962 return;
2963 }
2964
2965 // Now verify that the current nmethod (which contains p) is
2966 // in the code root list of the heap region containing the
2967 // object referenced by p.
2968
2969 T heap_oop = oopDesc::load_heap_oop(p);
2970 if (!oopDesc::is_null(heap_oop)) {
2971 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2972
2973 // Now fetch the region containing the object
2974 HeapRegion* hr = _g1h->heap_region_containing(obj);
2975 HeapRegionRemSet* hrrs = hr->rem_set();
2976 // Verify that the strong code root list for this region
2977 // contains the nmethod
2978 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2979 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2980 "from nmethod "PTR_FORMAT" not in strong "
2981 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2982 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2983 _failures = true;
2984 }
2985 }
2986 }
2987
2988 public:
2989 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2990 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2991
2992 void do_oop(oop* p) { do_oop_work(p); }
2993 void do_oop(narrowOop* p) { do_oop_work(p); }
2994
2995 void set_nmethod(nmethod* nm) { _nm = nm; }
2996 bool failures() { return _failures; }
2997 };
2998
2999 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3000 G1VerifyCodeRootOopClosure* _oop_cl;
3001
3002 public:
3003 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3004 _oop_cl(oop_cl) {}
3005
3006 void do_code_blob(CodeBlob* cb) {
3007 nmethod* nm = cb->as_nmethod_or_null();
3008 if (nm != NULL) {
3009 _oop_cl->set_nmethod(nm);
3010 nm->oops_do(_oop_cl);
3011 }
3012 }
3013 };
3014
3015 class YoungRefCounterClosure : public OopClosure {
3016 G1CollectedHeap* _g1h;
3017 int _count;
3018 public:
3019 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3020 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3021 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3022
3023 int count() { return _count; }
3024 void reset_count() { _count = 0; };
3025 };
3026
3027 class VerifyKlassClosure: public KlassClosure {
3028 YoungRefCounterClosure _young_ref_counter_closure;
3029 OopClosure *_oop_closure;
3030 public:
3031 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3032 void do_klass(Klass* k) {
3033 k->oops_do(_oop_closure);
3034
3035 _young_ref_counter_closure.reset_count();
3036 k->oops_do(&_young_ref_counter_closure);
3037 if (_young_ref_counter_closure.count() > 0) {
3038 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3039 }
3040 }
3041 };
3042
3043 class VerifyLivenessOopClosure: public OopClosure {
3044 G1CollectedHeap* _g1h;
3045 VerifyOption _vo;
3046 public:
3047 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3048 _g1h(g1h), _vo(vo)
3049 { }
3050 void do_oop(narrowOop *p) { do_oop_work(p); }
3051 void do_oop( oop *p) { do_oop_work(p); }
3052
3053 template <class T> void do_oop_work(T *p) {
3054 oop obj = oopDesc::load_decode_heap_oop(p);
3055 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3056 "Dead object referenced by a not dead object");
3057 }
3058 };
3059
3060 class VerifyObjsInRegionClosure: public ObjectClosure {
3061 private:
3062 G1CollectedHeap* _g1h;
3063 size_t _live_bytes;
3064 HeapRegion *_hr;
3065 VerifyOption _vo;
3066 public:
3067 // _vo == UsePrevMarking -> use "prev" marking information,
3068 // _vo == UseNextMarking -> use "next" marking information,
3069 // _vo == UseMarkWord -> use mark word from object header.
3070 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3071 : _live_bytes(0), _hr(hr), _vo(vo) {
3072 _g1h = G1CollectedHeap::heap();
3073 }
3074 void do_object(oop o) {
3075 VerifyLivenessOopClosure isLive(_g1h, _vo);
3076 assert(o != NULL, "Huh?");
3077 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3078 // If the object is alive according to the mark word,
3079 // then verify that the marking information agrees.
3080 // Note we can't verify the contra-positive of the
3081 // above: if the object is dead (according to the mark
3082 // word), it may not be marked, or may have been marked
3083 // but has since became dead, or may have been allocated
3084 // since the last marking.
3085 if (_vo == VerifyOption_G1UseMarkWord) {
3086 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3087 }
3088
3089 o->oop_iterate_no_header(&isLive);
3090 if (!_hr->obj_allocated_since_prev_marking(o)) {
3091 size_t obj_size = o->size(); // Make sure we don't overflow
3092 _live_bytes += (obj_size * HeapWordSize);
3093 }
3094 }
3095 }
3096 size_t live_bytes() { return _live_bytes; }
3097 };
3098
3099 class VerifyArchiveOopClosure: public OopClosure {
3100 public:
3101 VerifyArchiveOopClosure(HeapRegion *hr) { }
3102 void do_oop(narrowOop *p) { do_oop_work(p); }
3103 void do_oop( oop *p) { do_oop_work(p); }
3104
3105 template <class T> void do_oop_work(T *p) {
3106 oop obj = oopDesc::load_decode_heap_oop(p);
3107 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3108 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3109 p2i(p), p2i(obj)));
3110 }
3111 };
3112
3113 class VerifyArchiveRegionClosure: public ObjectClosure {
3114 public:
3115 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3116 // Verify that all object pointers are to archive regions.
3117 void do_object(oop o) {
3118 VerifyArchiveOopClosure checkOop(NULL);
3119 assert(o != NULL, "Should not be here for NULL oops");
3120 o->oop_iterate_no_header(&checkOop);
3121 }
3122 };
3123
3124 class VerifyRegionClosure: public HeapRegionClosure {
3125 private:
3126 bool _par;
3127 VerifyOption _vo;
3128 bool _failures;
3129 public:
3130 // _vo == UsePrevMarking -> use "prev" marking information,
3131 // _vo == UseNextMarking -> use "next" marking information,
3132 // _vo == UseMarkWord -> use mark word from object header.
3133 VerifyRegionClosure(bool par, VerifyOption vo)
3134 : _par(par),
3135 _vo(vo),
3136 _failures(false) {}
3137
3138 bool failures() {
3139 return _failures;
3140 }
3141
3142 bool doHeapRegion(HeapRegion* r) {
3143 // For archive regions, verify there are no heap pointers to
3144 // non-pinned regions. For all others, verify liveness info.
3145 if (r->is_archive()) {
3146 VerifyArchiveRegionClosure verify_oop_pointers(r);
3147 r->object_iterate(&verify_oop_pointers);
3148 return true;
3149 }
3150 if (!r->is_continues_humongous()) {
3151 bool failures = false;
3152 r->verify(_vo, &failures);
3153 if (failures) {
3154 _failures = true;
3155 } else {
3156 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3157 r->object_iterate(¬_dead_yet_cl);
3158 if (_vo != VerifyOption_G1UseNextMarking) {
3159 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3160 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3161 "max_live_bytes "SIZE_FORMAT" "
3162 "< calculated "SIZE_FORMAT,
3163 p2i(r->bottom()), p2i(r->end()),
3164 r->max_live_bytes(),
3165 not_dead_yet_cl.live_bytes());
3166 _failures = true;
3167 }
3168 } else {
3169 // When vo == UseNextMarking we cannot currently do a sanity
3170 // check on the live bytes as the calculation has not been
3171 // finalized yet.
3172 }
3173 }
3174 }
3175 return false; // stop the region iteration if we hit a failure
3176 }
3177 };
3178
3179 // This is the task used for parallel verification of the heap regions
3180
3181 class G1ParVerifyTask: public AbstractGangTask {
3182 private:
3183 G1CollectedHeap* _g1h;
3184 VerifyOption _vo;
3185 bool _failures;
3186 HeapRegionClaimer _hrclaimer;
3187
3188 public:
3189 // _vo == UsePrevMarking -> use "prev" marking information,
3190 // _vo == UseNextMarking -> use "next" marking information,
3191 // _vo == UseMarkWord -> use mark word from object header.
3192 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3193 AbstractGangTask("Parallel verify task"),
3194 _g1h(g1h),
3195 _vo(vo),
3196 _failures(false),
3197 _hrclaimer(g1h->workers()->active_workers()) {}
3198
3199 bool failures() {
3200 return _failures;
3201 }
3202
3203 void work(uint worker_id) {
3204 HandleMark hm;
3205 VerifyRegionClosure blk(true, _vo);
3206 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3207 if (blk.failures()) {
3208 _failures = true;
3209 }
3210 }
3211 };
3212
3213 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3214 if (SafepointSynchronize::is_at_safepoint()) {
3215 assert(Thread::current()->is_VM_thread(),
3216 "Expected to be executed serially by the VM thread at this point");
3217
3218 if (!silent) { gclog_or_tty->print("Roots "); }
3219 VerifyRootsClosure rootsCl(vo);
3220 VerifyKlassClosure klassCl(this, &rootsCl);
3221 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3222
3223 // We apply the relevant closures to all the oops in the
3224 // system dictionary, class loader data graph, the string table
3225 // and the nmethods in the code cache.
3226 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3227 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3228
3229 {
3230 G1RootProcessor root_processor(this, 1);
3231 root_processor.process_all_roots(&rootsCl,
3232 &cldCl,
3233 &blobsCl);
3234 }
3235
3236 bool failures = rootsCl.failures() || codeRootsCl.failures();
3237
3238 if (vo != VerifyOption_G1UseMarkWord) {
3239 // If we're verifying during a full GC then the region sets
3240 // will have been torn down at the start of the GC. Therefore
3241 // verifying the region sets will fail. So we only verify
3242 // the region sets when not in a full GC.
3243 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3244 verify_region_sets();
3245 }
3246
3247 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3248 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3249
3250 G1ParVerifyTask task(this, vo);
3251 workers()->run_task(&task);
3252 if (task.failures()) {
3253 failures = true;
3254 }
3255
3256 } else {
3257 VerifyRegionClosure blk(false, vo);
3258 heap_region_iterate(&blk);
3259 if (blk.failures()) {
3260 failures = true;
3261 }
3262 }
3263
3264 if (G1StringDedup::is_enabled()) {
3265 if (!silent) gclog_or_tty->print("StrDedup ");
3266 G1StringDedup::verify();
3267 }
3268
3269 if (failures) {
3270 gclog_or_tty->print_cr("Heap:");
3271 // It helps to have the per-region information in the output to
3272 // help us track down what went wrong. This is why we call
3273 // print_extended_on() instead of print_on().
3274 print_extended_on(gclog_or_tty);
3275 gclog_or_tty->cr();
3276 gclog_or_tty->flush();
3277 }
3278 guarantee(!failures, "there should not have been any failures");
3279 } else {
3280 if (!silent) {
3281 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3282 if (G1StringDedup::is_enabled()) {
3283 gclog_or_tty->print(", StrDedup");
3284 }
3285 gclog_or_tty->print(") ");
3286 }
3287 }
3288 }
3289
3290 void G1CollectedHeap::verify(bool silent) {
3291 verify(silent, VerifyOption_G1UsePrevMarking);
3292 }
3293
3294 double G1CollectedHeap::verify(bool guard, const char* msg) {
3295 double verify_time_ms = 0.0;
3296
3297 if (guard && total_collections() >= VerifyGCStartAt) {
3298 double verify_start = os::elapsedTime();
3299 HandleMark hm; // Discard invalid handles created during verification
3300 prepare_for_verify();
3301 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3302 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3303 }
3304
3305 return verify_time_ms;
3306 }
3307
3308 void G1CollectedHeap::verify_before_gc() {
3309 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3310 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3311 }
3312
3313 void G1CollectedHeap::verify_after_gc() {
3314 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3315 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3316 }
3317
3318 class PrintRegionClosure: public HeapRegionClosure {
3319 outputStream* _st;
3320 public:
3321 PrintRegionClosure(outputStream* st) : _st(st) {}
3322 bool doHeapRegion(HeapRegion* r) {
3323 r->print_on(_st);
3324 return false;
3325 }
3326 };
3327
3328 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3329 const HeapRegion* hr,
3330 const VerifyOption vo) const {
3331 switch (vo) {
3332 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3333 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3334 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3335 default: ShouldNotReachHere();
3336 }
3337 return false; // keep some compilers happy
3338 }
3339
3340 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3341 const VerifyOption vo) const {
3342 switch (vo) {
3343 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3344 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3345 case VerifyOption_G1UseMarkWord: {
3346 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3347 return !obj->is_gc_marked() && !hr->is_archive();
3348 }
3349 default: ShouldNotReachHere();
3350 }
3351 return false; // keep some compilers happy
3352 }
3353
3354 void G1CollectedHeap::print_on(outputStream* st) const {
3355 st->print(" %-20s", "garbage-first heap");
3356 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3357 capacity()/K, used_unlocked()/K);
3358 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3359 p2i(_hrm.reserved().start()),
3360 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3361 p2i(_hrm.reserved().end()));
3362 st->cr();
3363 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3364 uint young_regions = _young_list->length();
3365 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3366 (size_t) young_regions * HeapRegion::GrainBytes / K);
3367 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3368 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3369 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3370 st->cr();
3371 MetaspaceAux::print_on(st);
3372 }
3373
3374 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3375 print_on(st);
3376
3377 // Print the per-region information.
3378 st->cr();
3379 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3380 "HS=humongous(starts), HC=humongous(continues), "
3381 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3382 "PTAMS=previous top-at-mark-start, "
3383 "NTAMS=next top-at-mark-start)");
3384 PrintRegionClosure blk(st);
3385 heap_region_iterate(&blk);
3386 }
3387
3388 void G1CollectedHeap::print_on_error(outputStream* st) const {
3389 this->CollectedHeap::print_on_error(st);
3390
3391 if (_cm != NULL) {
3392 st->cr();
3393 _cm->print_on_error(st);
3394 }
3395 }
3396
3397 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3398 workers()->print_worker_threads_on(st);
3399 _cmThread->print_on(st);
3400 st->cr();
3401 _cm->print_worker_threads_on(st);
3402 _cg1r->print_worker_threads_on(st);
3403 if (G1StringDedup::is_enabled()) {
3404 G1StringDedup::print_worker_threads_on(st);
3405 }
3406 }
3407
3408 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3409 workers()->threads_do(tc);
3410 tc->do_thread(_cmThread);
3411 _cg1r->threads_do(tc);
3412 if (G1StringDedup::is_enabled()) {
3413 G1StringDedup::threads_do(tc);
3414 }
3415 }
3416
3417 void G1CollectedHeap::print_tracing_info() const {
3418 // We'll overload this to mean "trace GC pause statistics."
3419 if (TraceYoungGenTime || TraceOldGenTime) {
3420 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3421 // to that.
3422 g1_policy()->print_tracing_info();
3423 }
3424 if (G1SummarizeRSetStats) {
3425 g1_rem_set()->print_summary_info();
3426 }
3427 if (G1SummarizeConcMark) {
3428 concurrent_mark()->print_summary_info();
3429 }
3430 g1_policy()->print_yg_surv_rate_info();
3431 }
3432
3433 #ifndef PRODUCT
3434 // Helpful for debugging RSet issues.
3435
3436 class PrintRSetsClosure : public HeapRegionClosure {
3437 private:
3438 const char* _msg;
3439 size_t _occupied_sum;
3440
3441 public:
3442 bool doHeapRegion(HeapRegion* r) {
3443 HeapRegionRemSet* hrrs = r->rem_set();
3444 size_t occupied = hrrs->occupied();
3445 _occupied_sum += occupied;
3446
3447 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3448 HR_FORMAT_PARAMS(r));
3449 if (occupied == 0) {
3450 gclog_or_tty->print_cr(" RSet is empty");
3451 } else {
3452 hrrs->print();
3453 }
3454 gclog_or_tty->print_cr("----------");
3455 return false;
3456 }
3457
3458 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3459 gclog_or_tty->cr();
3460 gclog_or_tty->print_cr("========================================");
3461 gclog_or_tty->print_cr("%s", msg);
3462 gclog_or_tty->cr();
3463 }
3464
3465 ~PrintRSetsClosure() {
3466 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3467 gclog_or_tty->print_cr("========================================");
3468 gclog_or_tty->cr();
3469 }
3470 };
3471
3472 void G1CollectedHeap::print_cset_rsets() {
3473 PrintRSetsClosure cl("Printing CSet RSets");
3474 collection_set_iterate(&cl);
3475 }
3476
3477 void G1CollectedHeap::print_all_rsets() {
3478 PrintRSetsClosure cl("Printing All RSets");;
3479 heap_region_iterate(&cl);
3480 }
3481 #endif // PRODUCT
3482
3483 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3484 YoungList* young_list = heap()->young_list();
3485
3486 size_t eden_used_bytes = young_list->eden_used_bytes();
3487 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3488
3489 size_t eden_capacity_bytes =
3490 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3491
3492 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3493 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3494 }
3495
3496 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3497 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3498 gc_tracer->report_gc_heap_summary(when, heap_summary);
3499
3500 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3501 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3502 }
3503
3504
3505 G1CollectedHeap* G1CollectedHeap::heap() {
3506 CollectedHeap* heap = Universe::heap();
3507 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3508 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3509 return (G1CollectedHeap*)heap;
3510 }
3511
3512 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3513 // always_do_update_barrier = false;
3514 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3515 // Fill TLAB's and such
3516 accumulate_statistics_all_tlabs();
3517 ensure_parsability(true);
3518
3519 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3520 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3521 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3522 }
3523 }
3524
3525 void G1CollectedHeap::gc_epilogue(bool full) {
3526
3527 if (G1SummarizeRSetStats &&
3528 (G1SummarizeRSetStatsPeriod > 0) &&
3529 // we are at the end of the GC. Total collections has already been increased.
3530 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3531 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3532 }
3533
3534 // FIXME: what is this about?
3535 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3536 // is set.
3537 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3538 "derived pointer present"));
3539 // always_do_update_barrier = true;
3540
3541 resize_all_tlabs();
3542 allocation_context_stats().update(full);
3543
3544 // We have just completed a GC. Update the soft reference
3545 // policy with the new heap occupancy
3546 Universe::update_heap_info_at_gc();
3547 }
3548
3549 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3550 uint gc_count_before,
3551 bool* succeeded,
3552 GCCause::Cause gc_cause) {
3553 assert_heap_not_locked_and_not_at_safepoint();
3554 g1_policy()->record_stop_world_start();
3555 VM_G1IncCollectionPause op(gc_count_before,
3556 word_size,
3557 false, /* should_initiate_conc_mark */
3558 g1_policy()->max_pause_time_ms(),
3559 gc_cause);
3560
3561 op.set_allocation_context(AllocationContext::current());
3562 VMThread::execute(&op);
3563
3564 HeapWord* result = op.result();
3565 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3566 assert(result == NULL || ret_succeeded,
3567 "the result should be NULL if the VM did not succeed");
3568 *succeeded = ret_succeeded;
3569
3570 assert_heap_not_locked();
3571 return result;
3572 }
3573
3574 void
3575 G1CollectedHeap::doConcurrentMark() {
3576 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3577 if (!_cmThread->in_progress()) {
3578 _cmThread->set_started();
3579 CGC_lock->notify();
3580 }
3581 }
3582
3583 size_t G1CollectedHeap::pending_card_num() {
3584 size_t extra_cards = 0;
3585 JavaThread *curr = Threads::first();
3586 while (curr != NULL) {
3587 DirtyCardQueue& dcq = curr->dirty_card_queue();
3588 extra_cards += dcq.size();
3589 curr = curr->next();
3590 }
3591 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3592 size_t buffer_size = dcqs.buffer_size();
3593 size_t buffer_num = dcqs.completed_buffers_num();
3594
3595 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3596 // in bytes - not the number of 'entries'. We need to convert
3597 // into a number of cards.
3598 return (buffer_size * buffer_num + extra_cards) / oopSize;
3599 }
3600
3601 size_t G1CollectedHeap::cards_scanned() {
3602 return g1_rem_set()->cardsScanned();
3603 }
3604
3605 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3606 private:
3607 size_t _total_humongous;
3608 size_t _candidate_humongous;
3609
3610 DirtyCardQueue _dcq;
3611
3612 // We don't nominate objects with many remembered set entries, on
3613 // the assumption that such objects are likely still live.
3614 bool is_remset_small(HeapRegion* region) const {
3615 HeapRegionRemSet* const rset = region->rem_set();
3616 return G1EagerReclaimHumongousObjectsWithStaleRefs
3617 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3618 : rset->is_empty();
3619 }
3620
3621 bool is_typeArray_region(HeapRegion* region) const {
3622 return oop(region->bottom())->is_typeArray();
3623 }
3624
3625 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3626 assert(region->is_starts_humongous(), "Must start a humongous object");
3627
3628 // Candidate selection must satisfy the following constraints
3629 // while concurrent marking is in progress:
3630 //
3631 // * In order to maintain SATB invariants, an object must not be
3632 // reclaimed if it was allocated before the start of marking and
3633 // has not had its references scanned. Such an object must have
3634 // its references (including type metadata) scanned to ensure no
3635 // live objects are missed by the marking process. Objects
3636 // allocated after the start of concurrent marking don't need to
3637 // be scanned.
3638 //
3639 // * An object must not be reclaimed if it is on the concurrent
3640 // mark stack. Objects allocated after the start of concurrent
3641 // marking are never pushed on the mark stack.
3642 //
3643 // Nominating only objects allocated after the start of concurrent
3644 // marking is sufficient to meet both constraints. This may miss
3645 // some objects that satisfy the constraints, but the marking data
3646 // structures don't support efficiently performing the needed
3647 // additional tests or scrubbing of the mark stack.
3648 //
3649 // However, we presently only nominate is_typeArray() objects.
3650 // A humongous object containing references induces remembered
3651 // set entries on other regions. In order to reclaim such an
3652 // object, those remembered sets would need to be cleaned up.
3653 //
3654 // We also treat is_typeArray() objects specially, allowing them
3655 // to be reclaimed even if allocated before the start of
3656 // concurrent mark. For this we rely on mark stack insertion to
3657 // exclude is_typeArray() objects, preventing reclaiming an object
3658 // that is in the mark stack. We also rely on the metadata for
3659 // such objects to be built-in and so ensured to be kept live.
3660 // Frequent allocation and drop of large binary blobs is an
3661 // important use case for eager reclaim, and this special handling
3662 // may reduce needed headroom.
3663
3664 return is_typeArray_region(region) && is_remset_small(region);
3665 }
3666
3667 public:
3668 RegisterHumongousWithInCSetFastTestClosure()
3669 : _total_humongous(0),
3670 _candidate_humongous(0),
3671 _dcq(&JavaThread::dirty_card_queue_set()) {
3672 }
3673
3674 virtual bool doHeapRegion(HeapRegion* r) {
3675 if (!r->is_starts_humongous()) {
3676 return false;
3677 }
3678 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3679
3680 bool is_candidate = humongous_region_is_candidate(g1h, r);
3681 uint rindex = r->hrm_index();
3682 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3683 if (is_candidate) {
3684 _candidate_humongous++;
3685 g1h->register_humongous_region_with_cset(rindex);
3686 // Is_candidate already filters out humongous object with large remembered sets.
3687 // If we have a humongous object with a few remembered sets, we simply flush these
3688 // remembered set entries into the DCQS. That will result in automatic
3689 // re-evaluation of their remembered set entries during the following evacuation
3690 // phase.
3691 if (!r->rem_set()->is_empty()) {
3692 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3693 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3694 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3695 HeapRegionRemSetIterator hrrs(r->rem_set());
3696 size_t card_index;
3697 while (hrrs.has_next(card_index)) {
3698 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3699 // The remembered set might contain references to already freed
3700 // regions. Filter out such entries to avoid failing card table
3701 // verification.
3702 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3703 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3704 *card_ptr = CardTableModRefBS::dirty_card_val();
3705 _dcq.enqueue(card_ptr);
3706 }
3707 }
3708 }
3709 r->rem_set()->clear_locked();
3710 }
3711 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3712 }
3713 _total_humongous++;
3714
3715 return false;
3716 }
3717
3718 size_t total_humongous() const { return _total_humongous; }
3719 size_t candidate_humongous() const { return _candidate_humongous; }
3720
3721 void flush_rem_set_entries() { _dcq.flush(); }
3722 };
3723
3724 void G1CollectedHeap::register_humongous_regions_with_cset() {
3725 if (!G1EagerReclaimHumongousObjects) {
3726 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3727 return;
3728 }
3729 double time = os::elapsed_counter();
3730
3731 // Collect reclaim candidate information and register candidates with cset.
3732 RegisterHumongousWithInCSetFastTestClosure cl;
3733 heap_region_iterate(&cl);
3734
3735 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3736 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3737 cl.total_humongous(),
3738 cl.candidate_humongous());
3739 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3740
3741 // Finally flush all remembered set entries to re-check into the global DCQS.
3742 cl.flush_rem_set_entries();
3743 }
3744
3745 void
3746 G1CollectedHeap::setup_surviving_young_words() {
3747 assert(_surviving_young_words == NULL, "pre-condition");
3748 uint array_length = g1_policy()->young_cset_region_length();
3749 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3750 if (_surviving_young_words == NULL) {
3751 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3752 "Not enough space for young surv words summary.");
3753 }
3754 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3755 #ifdef ASSERT
3756 for (uint i = 0; i < array_length; ++i) {
3757 assert( _surviving_young_words[i] == 0, "memset above" );
3758 }
3759 #endif // !ASSERT
3760 }
3761
3762 void
3763 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3764 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3765 uint array_length = g1_policy()->young_cset_region_length();
3766 for (uint i = 0; i < array_length; ++i) {
3767 _surviving_young_words[i] += surv_young_words[i];
3768 }
3769 }
3770
3771 void
3772 G1CollectedHeap::cleanup_surviving_young_words() {
3773 guarantee( _surviving_young_words != NULL, "pre-condition" );
3774 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3775 _surviving_young_words = NULL;
3776 }
3777
3778 #ifdef ASSERT
3779 class VerifyCSetClosure: public HeapRegionClosure {
3780 public:
3781 bool doHeapRegion(HeapRegion* hr) {
3782 // Here we check that the CSet region's RSet is ready for parallel
3783 // iteration. The fields that we'll verify are only manipulated
3784 // when the region is part of a CSet and is collected. Afterwards,
3785 // we reset these fields when we clear the region's RSet (when the
3786 // region is freed) so they are ready when the region is
3787 // re-allocated. The only exception to this is if there's an
3788 // evacuation failure and instead of freeing the region we leave
3789 // it in the heap. In that case, we reset these fields during
3790 // evacuation failure handling.
3791 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3792
3793 // Here's a good place to add any other checks we'd like to
3794 // perform on CSet regions.
3795 return false;
3796 }
3797 };
3798 #endif // ASSERT
3799
3800 uint G1CollectedHeap::num_task_queues() const {
3801 return _task_queues->size();
3802 }
3803
3804 #if TASKQUEUE_STATS
3805 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3806 st->print_raw_cr("GC Task Stats");
3807 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3808 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3809 }
3810
3811 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3812 print_taskqueue_stats_hdr(st);
3813
3814 TaskQueueStats totals;
3815 const uint n = num_task_queues();
3816 for (uint i = 0; i < n; ++i) {
3817 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3818 totals += task_queue(i)->stats;
3819 }
3820 st->print_raw("tot "); totals.print(st); st->cr();
3821
3822 DEBUG_ONLY(totals.verify());
3823 }
3824
3825 void G1CollectedHeap::reset_taskqueue_stats() {
3826 const uint n = num_task_queues();
3827 for (uint i = 0; i < n; ++i) {
3828 task_queue(i)->stats.reset();
3829 }
3830 }
3831 #endif // TASKQUEUE_STATS
3832
3833 void G1CollectedHeap::log_gc_header() {
3834 if (!G1Log::fine()) {
3835 return;
3836 }
3837
3838 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3839
3840 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3841 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3842 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3843
3844 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3845 }
3846
3847 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3848 if (!G1Log::fine()) {
3849 return;
3850 }
3851
3852 if (G1Log::finer()) {
3853 if (evacuation_failed()) {
3854 gclog_or_tty->print(" (to-space exhausted)");
3855 }
3856 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3857 g1_policy()->phase_times()->note_gc_end();
3858 g1_policy()->phase_times()->print(pause_time_sec);
3859 g1_policy()->print_detailed_heap_transition();
3860 } else {
3861 if (evacuation_failed()) {
3862 gclog_or_tty->print("--");
3863 }
3864 g1_policy()->print_heap_transition();
3865 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3866 }
3867 gclog_or_tty->flush();
3868 }
3869
3870 void G1CollectedHeap::wait_for_root_region_scanning() {
3871 double scan_wait_start = os::elapsedTime();
3872 // We have to wait until the CM threads finish scanning the
3873 // root regions as it's the only way to ensure that all the
3874 // objects on them have been correctly scanned before we start
3875 // moving them during the GC.
3876 bool waited = _cm->root_regions()->wait_until_scan_finished();
3877 double wait_time_ms = 0.0;
3878 if (waited) {
3879 double scan_wait_end = os::elapsedTime();
3880 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3881 }
3882 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3883 }
3884
3885 bool
3886 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3887 assert_at_safepoint(true /* should_be_vm_thread */);
3888 guarantee(!is_gc_active(), "collection is not reentrant");
3889
3890 if (GC_locker::check_active_before_gc()) {
3891 return false;
3892 }
3893
3894 _gc_timer_stw->register_gc_start();
3895
3896 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3897
3898 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3899 ResourceMark rm;
3900
3901 wait_for_root_region_scanning();
3902
3903 G1Log::update_level();
3904 print_heap_before_gc();
3905 trace_heap_before_gc(_gc_tracer_stw);
3906
3907 verify_region_sets_optional();
3908 verify_dirty_young_regions();
3909
3910 // This call will decide whether this pause is an initial-mark
3911 // pause. If it is, during_initial_mark_pause() will return true
3912 // for the duration of this pause.
3913 g1_policy()->decide_on_conc_mark_initiation();
3914
3915 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3916 assert(!collector_state()->during_initial_mark_pause() ||
3917 collector_state()->gcs_are_young(), "sanity");
3918
3919 // We also do not allow mixed GCs during marking.
3920 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3921
3922 // Record whether this pause is an initial mark. When the current
3923 // thread has completed its logging output and it's safe to signal
3924 // the CM thread, the flag's value in the policy has been reset.
3925 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3926
3927 // Inner scope for scope based logging, timers, and stats collection
3928 {
3929 EvacuationInfo evacuation_info;
3930
3931 if (collector_state()->during_initial_mark_pause()) {
3932 // We are about to start a marking cycle, so we increment the
3933 // full collection counter.
3934 increment_old_marking_cycles_started();
3935 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3936 }
3937
3938 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3939
3940 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3941
3942 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3943 workers()->active_workers(),
3944 Threads::number_of_non_daemon_threads());
3945 workers()->set_active_workers(active_workers);
3946
3947 double pause_start_sec = os::elapsedTime();
3948 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
3949 log_gc_header();
3950
3951 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3952 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3953
3954 // If the secondary_free_list is not empty, append it to the
3955 // free_list. No need to wait for the cleanup operation to finish;
3956 // the region allocation code will check the secondary_free_list
3957 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3958 // set, skip this step so that the region allocation code has to
3959 // get entries from the secondary_free_list.
3960 if (!G1StressConcRegionFreeing) {
3961 append_secondary_free_list_if_not_empty_with_lock();
3962 }
3963
3964 assert(check_young_list_well_formed(), "young list should be well formed");
3965
3966 // Don't dynamically change the number of GC threads this early. A value of
3967 // 0 is used to indicate serial work. When parallel work is done,
3968 // it will be set.
3969
3970 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3971 IsGCActiveMark x;
3972
3973 gc_prologue(false);
3974 increment_total_collections(false /* full gc */);
3975 increment_gc_time_stamp();
3976
3977 verify_before_gc();
3978
3979 check_bitmaps("GC Start");
3980
3981 COMPILER2_PRESENT(DerivedPointerTable::clear());
3982
3983 // Please see comment in g1CollectedHeap.hpp and
3984 // G1CollectedHeap::ref_processing_init() to see how
3985 // reference processing currently works in G1.
3986
3987 // Enable discovery in the STW reference processor
3988 ref_processor_stw()->enable_discovery();
3989
3990 {
3991 // We want to temporarily turn off discovery by the
3992 // CM ref processor, if necessary, and turn it back on
3993 // on again later if we do. Using a scoped
3994 // NoRefDiscovery object will do this.
3995 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3996
3997 // Forget the current alloc region (we might even choose it to be part
3998 // of the collection set!).
3999 _allocator->release_mutator_alloc_region();
4000
4001 // We should call this after we retire the mutator alloc
4002 // region(s) so that all the ALLOC / RETIRE events are generated
4003 // before the start GC event.
4004 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4005
4006 // This timing is only used by the ergonomics to handle our pause target.
4007 // It is unclear why this should not include the full pause. We will
4008 // investigate this in CR 7178365.
4009 //
4010 // Preserving the old comment here if that helps the investigation:
4011 //
4012 // The elapsed time induced by the start time below deliberately elides
4013 // the possible verification above.
4014 double sample_start_time_sec = os::elapsedTime();
4015
4016 #if YOUNG_LIST_VERBOSE
4017 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4018 _young_list->print();
4019 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4020 #endif // YOUNG_LIST_VERBOSE
4021
4022 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4023
4024 #if YOUNG_LIST_VERBOSE
4025 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4026 _young_list->print();
4027 #endif // YOUNG_LIST_VERBOSE
4028
4029 if (collector_state()->during_initial_mark_pause()) {
4030 concurrent_mark()->checkpointRootsInitialPre();
4031 }
4032
4033 #if YOUNG_LIST_VERBOSE
4034 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4035 _young_list->print();
4036 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4037 #endif // YOUNG_LIST_VERBOSE
4038
4039 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4040
4041 register_humongous_regions_with_cset();
4042
4043 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4044
4045 _cm->note_start_of_gc();
4046 // We call this after finalize_cset() to
4047 // ensure that the CSet has been finalized.
4048 _cm->verify_no_cset_oops();
4049
4050 if (_hr_printer.is_active()) {
4051 HeapRegion* hr = g1_policy()->collection_set();
4052 while (hr != NULL) {
4053 _hr_printer.cset(hr);
4054 hr = hr->next_in_collection_set();
4055 }
4056 }
4057
4058 #ifdef ASSERT
4059 VerifyCSetClosure cl;
4060 collection_set_iterate(&cl);
4061 #endif // ASSERT
4062
4063 setup_surviving_young_words();
4064
4065 // Initialize the GC alloc regions.
4066 _allocator->init_gc_alloc_regions(evacuation_info);
4067
4068 // Actually do the work...
4069 evacuate_collection_set(evacuation_info);
4070
4071 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4072
4073 eagerly_reclaim_humongous_regions();
4074
4075 g1_policy()->clear_collection_set();
4076
4077 cleanup_surviving_young_words();
4078
4079 // Start a new incremental collection set for the next pause.
4080 g1_policy()->start_incremental_cset_building();
4081
4082 clear_cset_fast_test();
4083
4084 _young_list->reset_sampled_info();
4085
4086 // Don't check the whole heap at this point as the
4087 // GC alloc regions from this pause have been tagged
4088 // as survivors and moved on to the survivor list.
4089 // Survivor regions will fail the !is_young() check.
4090 assert(check_young_list_empty(false /* check_heap */),
4091 "young list should be empty");
4092
4093 #if YOUNG_LIST_VERBOSE
4094 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4095 _young_list->print();
4096 #endif // YOUNG_LIST_VERBOSE
4097
4098 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4099 _young_list->first_survivor_region(),
4100 _young_list->last_survivor_region());
4101
4102 _young_list->reset_auxilary_lists();
4103
4104 if (evacuation_failed()) {
4105 _allocator->set_used(recalculate_used());
4106 if (_archive_allocator != NULL) {
4107 _archive_allocator->clear_used();
4108 }
4109 for (uint i = 0; i < ParallelGCThreads; i++) {
4110 if (_evacuation_failed_info_array[i].has_failed()) {
4111 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4112 }
4113 }
4114 } else {
4115 // The "used" of the the collection set have already been subtracted
4116 // when they were freed. Add in the bytes evacuated.
4117 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4118 }
4119
4120 if (collector_state()->during_initial_mark_pause()) {
4121 // We have to do this before we notify the CM threads that
4122 // they can start working to make sure that all the
4123 // appropriate initialization is done on the CM object.
4124 concurrent_mark()->checkpointRootsInitialPost();
4125 collector_state()->set_mark_in_progress(true);
4126 // Note that we don't actually trigger the CM thread at
4127 // this point. We do that later when we're sure that
4128 // the current thread has completed its logging output.
4129 }
4130
4131 allocate_dummy_regions();
4132
4133 #if YOUNG_LIST_VERBOSE
4134 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4135 _young_list->print();
4136 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4137 #endif // YOUNG_LIST_VERBOSE
4138
4139 _allocator->init_mutator_alloc_region();
4140
4141 {
4142 size_t expand_bytes = g1_policy()->expansion_amount();
4143 if (expand_bytes > 0) {
4144 size_t bytes_before = capacity();
4145 // No need for an ergo verbose message here,
4146 // expansion_amount() does this when it returns a value > 0.
4147 if (!expand(expand_bytes)) {
4148 // We failed to expand the heap. Cannot do anything about it.
4149 }
4150 }
4151 }
4152
4153 // We redo the verification but now wrt to the new CSet which
4154 // has just got initialized after the previous CSet was freed.
4155 _cm->verify_no_cset_oops();
4156 _cm->note_end_of_gc();
4157
4158 // This timing is only used by the ergonomics to handle our pause target.
4159 // It is unclear why this should not include the full pause. We will
4160 // investigate this in CR 7178365.
4161 double sample_end_time_sec = os::elapsedTime();
4162 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4163 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4164
4165 MemoryService::track_memory_usage();
4166
4167 // In prepare_for_verify() below we'll need to scan the deferred
4168 // update buffers to bring the RSets up-to-date if
4169 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4170 // the update buffers we'll probably need to scan cards on the
4171 // regions we just allocated to (i.e., the GC alloc
4172 // regions). However, during the last GC we called
4173 // set_saved_mark() on all the GC alloc regions, so card
4174 // scanning might skip the [saved_mark_word()...top()] area of
4175 // those regions (i.e., the area we allocated objects into
4176 // during the last GC). But it shouldn't. Given that
4177 // saved_mark_word() is conditional on whether the GC time stamp
4178 // on the region is current or not, by incrementing the GC time
4179 // stamp here we invalidate all the GC time stamps on all the
4180 // regions and saved_mark_word() will simply return top() for
4181 // all the regions. This is a nicer way of ensuring this rather
4182 // than iterating over the regions and fixing them. In fact, the
4183 // GC time stamp increment here also ensures that
4184 // saved_mark_word() will return top() between pauses, i.e.,
4185 // during concurrent refinement. So we don't need the
4186 // is_gc_active() check to decided which top to use when
4187 // scanning cards (see CR 7039627).
4188 increment_gc_time_stamp();
4189
4190 verify_after_gc();
4191 check_bitmaps("GC End");
4192
4193 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4194 ref_processor_stw()->verify_no_references_recorded();
4195
4196 // CM reference discovery will be re-enabled if necessary.
4197 }
4198
4199 // We should do this after we potentially expand the heap so
4200 // that all the COMMIT events are generated before the end GC
4201 // event, and after we retire the GC alloc regions so that all
4202 // RETIRE events are generated before the end GC event.
4203 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4204
4205 #ifdef TRACESPINNING
4206 ParallelTaskTerminator::print_termination_counts();
4207 #endif
4208
4209 gc_epilogue(false);
4210 }
4211
4212 // Print the remainder of the GC log output.
4213 log_gc_footer(os::elapsedTime() - pause_start_sec);
4214
4215 // It is not yet to safe to tell the concurrent mark to
4216 // start as we have some optional output below. We don't want the
4217 // output from the concurrent mark thread interfering with this
4218 // logging output either.
4219
4220 _hrm.verify_optional();
4221 verify_region_sets_optional();
4222
4223 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4224 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4225
4226 print_heap_after_gc();
4227 trace_heap_after_gc(_gc_tracer_stw);
4228
4229 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4230 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4231 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4232 // before any GC notifications are raised.
4233 g1mm()->update_sizes();
4234
4235 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4236 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4237 _gc_timer_stw->register_gc_end();
4238 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4239 }
4240 // It should now be safe to tell the concurrent mark thread to start
4241 // without its logging output interfering with the logging output
4242 // that came from the pause.
4243
4244 if (should_start_conc_mark) {
4245 // CAUTION: after the doConcurrentMark() call below,
4246 // the concurrent marking thread(s) could be running
4247 // concurrently with us. Make sure that anything after
4248 // this point does not assume that we are the only GC thread
4249 // running. Note: of course, the actual marking work will
4250 // not start until the safepoint itself is released in
4251 // SuspendibleThreadSet::desynchronize().
4252 doConcurrentMark();
4253 }
4254
4255 return true;
4256 }
4257
4258 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4259 _drain_in_progress = false;
4260 set_evac_failure_closure(cl);
4261 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4262 }
4263
4264 void G1CollectedHeap::finalize_for_evac_failure() {
4265 assert(_evac_failure_scan_stack != NULL &&
4266 _evac_failure_scan_stack->length() == 0,
4267 "Postcondition");
4268 assert(!_drain_in_progress, "Postcondition");
4269 delete _evac_failure_scan_stack;
4270 _evac_failure_scan_stack = NULL;
4271 }
4272
4273 void G1CollectedHeap::remove_self_forwarding_pointers() {
4274 double remove_self_forwards_start = os::elapsedTime();
4275
4276 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4277 workers()->run_task(&rsfp_task);
4278
4279 // Now restore saved marks, if any.
4280 assert(_objs_with_preserved_marks.size() ==
4281 _preserved_marks_of_objs.size(), "Both or none.");
4282 while (!_objs_with_preserved_marks.is_empty()) {
4283 oop obj = _objs_with_preserved_marks.pop();
4284 markOop m = _preserved_marks_of_objs.pop();
4285 obj->set_mark(m);
4286 }
4287 _objs_with_preserved_marks.clear(true);
4288 _preserved_marks_of_objs.clear(true);
4289
4290 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4291 }
4292
4293 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4294 _evac_failure_scan_stack->push(obj);
4295 }
4296
4297 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4298 assert(_evac_failure_scan_stack != NULL, "precondition");
4299
4300 while (_evac_failure_scan_stack->length() > 0) {
4301 oop obj = _evac_failure_scan_stack->pop();
4302 _evac_failure_closure->set_region(heap_region_containing(obj));
4303 obj->oop_iterate_backwards(_evac_failure_closure);
4304 }
4305 }
4306
4307 oop
4308 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4309 oop old) {
4310 assert(obj_in_cs(old),
4311 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4312 p2i(old)));
4313 markOop m = old->mark();
4314 oop forward_ptr = old->forward_to_atomic(old);
4315 if (forward_ptr == NULL) {
4316 // Forward-to-self succeeded.
4317 assert(_par_scan_state != NULL, "par scan state");
4318 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4319 uint queue_num = _par_scan_state->queue_num();
4320
4321 _evacuation_failed = true;
4322 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4323 if (_evac_failure_closure != cl) {
4324 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4325 assert(!_drain_in_progress,
4326 "Should only be true while someone holds the lock.");
4327 // Set the global evac-failure closure to the current thread's.
4328 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4329 set_evac_failure_closure(cl);
4330 // Now do the common part.
4331 handle_evacuation_failure_common(old, m);
4332 // Reset to NULL.
4333 set_evac_failure_closure(NULL);
4334 } else {
4335 // The lock is already held, and this is recursive.
4336 assert(_drain_in_progress, "This should only be the recursive case.");
4337 handle_evacuation_failure_common(old, m);
4338 }
4339 return old;
4340 } else {
4341 // Forward-to-self failed. Either someone else managed to allocate
4342 // space for this object (old != forward_ptr) or they beat us in
4343 // self-forwarding it (old == forward_ptr).
4344 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4345 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4346 "should not be in the CSet",
4347 p2i(old), p2i(forward_ptr)));
4348 return forward_ptr;
4349 }
4350 }
4351
4352 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4353 preserve_mark_if_necessary(old, m);
4354
4355 HeapRegion* r = heap_region_containing(old);
4356 if (!r->evacuation_failed()) {
4357 r->set_evacuation_failed(true);
4358 _hr_printer.evac_failure(r);
4359 }
4360
4361 push_on_evac_failure_scan_stack(old);
4362
4363 if (!_drain_in_progress) {
4364 // prevent recursion in copy_to_survivor_space()
4365 _drain_in_progress = true;
4366 drain_evac_failure_scan_stack();
4367 _drain_in_progress = false;
4368 }
4369 }
4370
4371 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4372 assert(evacuation_failed(), "Oversaving!");
4373 // We want to call the "for_promotion_failure" version only in the
4374 // case of a promotion failure.
4375 if (m->must_be_preserved_for_promotion_failure(obj)) {
4376 _objs_with_preserved_marks.push(obj);
4377 _preserved_marks_of_objs.push(m);
4378 }
4379 }
4380
4381 void G1ParCopyHelper::mark_object(oop obj) {
4382 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4383
4384 // We know that the object is not moving so it's safe to read its size.
4385 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4386 }
4387
4388 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4389 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4390 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4391 assert(from_obj != to_obj, "should not be self-forwarded");
4392
4393 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4394 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4395
4396 // The object might be in the process of being copied by another
4397 // worker so we cannot trust that its to-space image is
4398 // well-formed. So we have to read its size from its from-space
4399 // image which we know should not be changing.
4400 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4401 }
4402
4403 template <class T>
4404 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4405 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4406 _scanned_klass->record_modified_oops();
4407 }
4408 }
4409
4410 template <G1Barrier barrier, G1Mark do_mark_object>
4411 template <class T>
4412 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4413 T heap_oop = oopDesc::load_heap_oop(p);
4414
4415 if (oopDesc::is_null(heap_oop)) {
4416 return;
4417 }
4418
4419 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4420
4421 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4422
4423 const InCSetState state = _g1->in_cset_state(obj);
4424 if (state.is_in_cset()) {
4425 oop forwardee;
4426 markOop m = obj->mark();
4427 if (m->is_marked()) {
4428 forwardee = (oop) m->decode_pointer();
4429 } else {
4430 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4431 }
4432 assert(forwardee != NULL, "forwardee should not be NULL");
4433 oopDesc::encode_store_heap_oop(p, forwardee);
4434 if (do_mark_object != G1MarkNone && forwardee != obj) {
4435 // If the object is self-forwarded we don't need to explicitly
4436 // mark it, the evacuation failure protocol will do so.
4437 mark_forwarded_object(obj, forwardee);
4438 }
4439
4440 if (barrier == G1BarrierKlass) {
4441 do_klass_barrier(p, forwardee);
4442 }
4443 } else {
4444 if (state.is_humongous()) {
4445 _g1->set_humongous_is_live(obj);
4446 }
4447 // The object is not in collection set. If we're a root scanning
4448 // closure during an initial mark pause then attempt to mark the object.
4449 if (do_mark_object == G1MarkFromRoot) {
4450 mark_object(obj);
4451 }
4452 }
4453
4454 if (barrier == G1BarrierEvac) {
4455 _par_scan_state->update_rs(_from, p, _worker_id);
4456 }
4457 }
4458
4459 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4460 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4461
4462 class G1ParEvacuateFollowersClosure : public VoidClosure {
4463 protected:
4464 G1CollectedHeap* _g1h;
4465 G1ParScanThreadState* _par_scan_state;
4466 RefToScanQueueSet* _queues;
4467 ParallelTaskTerminator* _terminator;
4468
4469 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4470 RefToScanQueueSet* queues() { return _queues; }
4471 ParallelTaskTerminator* terminator() { return _terminator; }
4472
4473 public:
4474 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4475 G1ParScanThreadState* par_scan_state,
4476 RefToScanQueueSet* queues,
4477 ParallelTaskTerminator* terminator)
4478 : _g1h(g1h), _par_scan_state(par_scan_state),
4479 _queues(queues), _terminator(terminator) {}
4480
4481 void do_void();
4482
4483 private:
4484 inline bool offer_termination();
4485 };
4486
4487 bool G1ParEvacuateFollowersClosure::offer_termination() {
4488 G1ParScanThreadState* const pss = par_scan_state();
4489 pss->start_term_time();
4490 const bool res = terminator()->offer_termination();
4491 pss->end_term_time();
4492 return res;
4493 }
4494
4495 void G1ParEvacuateFollowersClosure::do_void() {
4496 G1ParScanThreadState* const pss = par_scan_state();
4497 pss->trim_queue();
4498 do {
4499 pss->steal_and_trim_queue(queues());
4500 } while (!offer_termination());
4501 }
4502
4503 class G1KlassScanClosure : public KlassClosure {
4504 G1ParCopyHelper* _closure;
4505 bool _process_only_dirty;
4506 int _count;
4507 public:
4508 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4509 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4510 void do_klass(Klass* klass) {
4511 // If the klass has not been dirtied we know that there's
4512 // no references into the young gen and we can skip it.
4513 if (!_process_only_dirty || klass->has_modified_oops()) {
4514 // Clean the klass since we're going to scavenge all the metadata.
4515 klass->clear_modified_oops();
4516
4517 // Tell the closure that this klass is the Klass to scavenge
4518 // and is the one to dirty if oops are left pointing into the young gen.
4519 _closure->set_scanned_klass(klass);
4520
4521 klass->oops_do(_closure);
4522
4523 _closure->set_scanned_klass(NULL);
4524 }
4525 _count++;
4526 }
4527 };
4528
4529 class G1ParTask : public AbstractGangTask {
4530 protected:
4531 G1CollectedHeap* _g1h;
4532 RefToScanQueueSet *_queues;
4533 G1RootProcessor* _root_processor;
4534 ParallelTaskTerminator _terminator;
4535 uint _n_workers;
4536
4537 Mutex _stats_lock;
4538 Mutex* stats_lock() { return &_stats_lock; }
4539
4540 public:
4541 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4542 : AbstractGangTask("G1 collection"),
4543 _g1h(g1h),
4544 _queues(task_queues),
4545 _root_processor(root_processor),
4546 _terminator(n_workers, _queues),
4547 _n_workers(n_workers),
4548 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4549 {}
4550
4551 RefToScanQueueSet* queues() { return _queues; }
4552
4553 RefToScanQueue *work_queue(int i) {
4554 return queues()->queue(i);
4555 }
4556
4557 ParallelTaskTerminator* terminator() { return &_terminator; }
4558
4559 // Helps out with CLD processing.
4560 //
4561 // During InitialMark we need to:
4562 // 1) Scavenge all CLDs for the young GC.
4563 // 2) Mark all objects directly reachable from strong CLDs.
4564 template <G1Mark do_mark_object>
4565 class G1CLDClosure : public CLDClosure {
4566 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4567 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4568 G1KlassScanClosure _klass_in_cld_closure;
4569 bool _claim;
4570
4571 public:
4572 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4573 bool only_young, bool claim)
4574 : _oop_closure(oop_closure),
4575 _oop_in_klass_closure(oop_closure->g1(),
4576 oop_closure->pss(),
4577 oop_closure->rp()),
4578 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4579 _claim(claim) {
4580
4581 }
4582
4583 void do_cld(ClassLoaderData* cld) {
4584 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4585 }
4586 };
4587
4588 void work(uint worker_id) {
4589 if (worker_id >= _n_workers) return; // no work needed this round
4590
4591 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4592
4593 {
4594 ResourceMark rm;
4595 HandleMark hm;
4596
4597 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4598
4599 G1ParScanThreadState pss(_g1h, worker_id, rp);
4600 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4601
4602 pss.set_evac_failure_closure(&evac_failure_cl);
4603
4604 bool only_young = _g1h->collector_state()->gcs_are_young();
4605
4606 // Non-IM young GC.
4607 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4608 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4609 only_young, // Only process dirty klasses.
4610 false); // No need to claim CLDs.
4611 // IM young GC.
4612 // Strong roots closures.
4613 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4614 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4615 false, // Process all klasses.
4616 true); // Need to claim CLDs.
4617 // Weak roots closures.
4618 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4619 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4620 false, // Process all klasses.
4621 true); // Need to claim CLDs.
4622
4623 OopClosure* strong_root_cl;
4624 OopClosure* weak_root_cl;
4625 CLDClosure* strong_cld_cl;
4626 CLDClosure* weak_cld_cl;
4627
4628 bool trace_metadata = false;
4629
4630 if (_g1h->collector_state()->during_initial_mark_pause()) {
4631 // We also need to mark copied objects.
4632 strong_root_cl = &scan_mark_root_cl;
4633 strong_cld_cl = &scan_mark_cld_cl;
4634 if (ClassUnloadingWithConcurrentMark) {
4635 weak_root_cl = &scan_mark_weak_root_cl;
4636 weak_cld_cl = &scan_mark_weak_cld_cl;
4637 trace_metadata = true;
4638 } else {
4639 weak_root_cl = &scan_mark_root_cl;
4640 weak_cld_cl = &scan_mark_cld_cl;
4641 }
4642 } else {
4643 strong_root_cl = &scan_only_root_cl;
4644 weak_root_cl = &scan_only_root_cl;
4645 strong_cld_cl = &scan_only_cld_cl;
4646 weak_cld_cl = &scan_only_cld_cl;
4647 }
4648
4649 pss.start_strong_roots();
4650
4651 _root_processor->evacuate_roots(strong_root_cl,
4652 weak_root_cl,
4653 strong_cld_cl,
4654 weak_cld_cl,
4655 trace_metadata,
4656 worker_id);
4657
4658 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4659 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4660 weak_root_cl,
4661 worker_id);
4662 pss.end_strong_roots();
4663
4664 {
4665 double start = os::elapsedTime();
4666 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4667 evac.do_void();
4668 double elapsed_sec = os::elapsedTime() - start;
4669 double term_sec = pss.term_time();
4670 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4671 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4672 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4673 }
4674 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4675 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4676
4677 if (PrintTerminationStats) {
4678 MutexLocker x(stats_lock());
4679 pss.print_termination_stats(worker_id);
4680 }
4681
4682 assert(pss.queue_is_empty(), "should be empty");
4683
4684 // Close the inner scope so that the ResourceMark and HandleMark
4685 // destructors are executed here and are included as part of the
4686 // "GC Worker Time".
4687 }
4688 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4689 }
4690 };
4691
4692 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4693 private:
4694 BoolObjectClosure* _is_alive;
4695 int _initial_string_table_size;
4696 int _initial_symbol_table_size;
4697
4698 bool _process_strings;
4699 int _strings_processed;
4700 int _strings_removed;
4701
4702 bool _process_symbols;
4703 int _symbols_processed;
4704 int _symbols_removed;
4705
4706 public:
4707 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4708 AbstractGangTask("String/Symbol Unlinking"),
4709 _is_alive(is_alive),
4710 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4711 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4712
4713 _initial_string_table_size = StringTable::the_table()->table_size();
4714 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4715 if (process_strings) {
4716 StringTable::clear_parallel_claimed_index();
4717 }
4718 if (process_symbols) {
4719 SymbolTable::clear_parallel_claimed_index();
4720 }
4721 }
4722
4723 ~G1StringSymbolTableUnlinkTask() {
4724 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4725 err_msg("claim value %d after unlink less than initial string table size %d",
4726 StringTable::parallel_claimed_index(), _initial_string_table_size));
4727 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4728 err_msg("claim value %d after unlink less than initial symbol table size %d",
4729 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4730
4731 if (G1TraceStringSymbolTableScrubbing) {
4732 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4733 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4734 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4735 strings_processed(), strings_removed(),
4736 symbols_processed(), symbols_removed());
4737 }
4738 }
4739
4740 void work(uint worker_id) {
4741 int strings_processed = 0;
4742 int strings_removed = 0;
4743 int symbols_processed = 0;
4744 int symbols_removed = 0;
4745 if (_process_strings) {
4746 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4747 Atomic::add(strings_processed, &_strings_processed);
4748 Atomic::add(strings_removed, &_strings_removed);
4749 }
4750 if (_process_symbols) {
4751 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4752 Atomic::add(symbols_processed, &_symbols_processed);
4753 Atomic::add(symbols_removed, &_symbols_removed);
4754 }
4755 }
4756
4757 size_t strings_processed() const { return (size_t)_strings_processed; }
4758 size_t strings_removed() const { return (size_t)_strings_removed; }
4759
4760 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4761 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4762 };
4763
4764 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4765 private:
4766 static Monitor* _lock;
4767
4768 BoolObjectClosure* const _is_alive;
4769 const bool _unloading_occurred;
4770 const uint _num_workers;
4771
4772 // Variables used to claim nmethods.
4773 nmethod* _first_nmethod;
4774 volatile nmethod* _claimed_nmethod;
4775
4776 // The list of nmethods that need to be processed by the second pass.
4777 volatile nmethod* _postponed_list;
4778 volatile uint _num_entered_barrier;
4779
4780 public:
4781 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4782 _is_alive(is_alive),
4783 _unloading_occurred(unloading_occurred),
4784 _num_workers(num_workers),
4785 _first_nmethod(NULL),
4786 _claimed_nmethod(NULL),
4787 _postponed_list(NULL),
4788 _num_entered_barrier(0)
4789 {
4790 nmethod::increase_unloading_clock();
4791 // Get first alive nmethod
4792 NMethodIterator iter = NMethodIterator();
4793 if(iter.next_alive()) {
4794 _first_nmethod = iter.method();
4795 }
4796 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4797 }
4798
4799 ~G1CodeCacheUnloadingTask() {
4800 CodeCache::verify_clean_inline_caches();
4801
4802 CodeCache::set_needs_cache_clean(false);
4803 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4804
4805 CodeCache::verify_icholder_relocations();
4806 }
4807
4808 private:
4809 void add_to_postponed_list(nmethod* nm) {
4810 nmethod* old;
4811 do {
4812 old = (nmethod*)_postponed_list;
4813 nm->set_unloading_next(old);
4814 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4815 }
4816
4817 void clean_nmethod(nmethod* nm) {
4818 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4819
4820 if (postponed) {
4821 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4822 add_to_postponed_list(nm);
4823 }
4824
4825 // Mark that this thread has been cleaned/unloaded.
4826 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4827 nm->set_unloading_clock(nmethod::global_unloading_clock());
4828 }
4829
4830 void clean_nmethod_postponed(nmethod* nm) {
4831 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4832 }
4833
4834 static const int MaxClaimNmethods = 16;
4835
4836 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4837 nmethod* first;
4838 NMethodIterator last;
4839
4840 do {
4841 *num_claimed_nmethods = 0;
4842
4843 first = (nmethod*)_claimed_nmethod;
4844 last = NMethodIterator(first);
4845
4846 if (first != NULL) {
4847
4848 for (int i = 0; i < MaxClaimNmethods; i++) {
4849 if (!last.next_alive()) {
4850 break;
4851 }
4852 claimed_nmethods[i] = last.method();
4853 (*num_claimed_nmethods)++;
4854 }
4855 }
4856
4857 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4858 }
4859
4860 nmethod* claim_postponed_nmethod() {
4861 nmethod* claim;
4862 nmethod* next;
4863
4864 do {
4865 claim = (nmethod*)_postponed_list;
4866 if (claim == NULL) {
4867 return NULL;
4868 }
4869
4870 next = claim->unloading_next();
4871
4872 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4873
4874 return claim;
4875 }
4876
4877 public:
4878 // Mark that we're done with the first pass of nmethod cleaning.
4879 void barrier_mark(uint worker_id) {
4880 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4881 _num_entered_barrier++;
4882 if (_num_entered_barrier == _num_workers) {
4883 ml.notify_all();
4884 }
4885 }
4886
4887 // See if we have to wait for the other workers to
4888 // finish their first-pass nmethod cleaning work.
4889 void barrier_wait(uint worker_id) {
4890 if (_num_entered_barrier < _num_workers) {
4891 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4892 while (_num_entered_barrier < _num_workers) {
4893 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4894 }
4895 }
4896 }
4897
4898 // Cleaning and unloading of nmethods. Some work has to be postponed
4899 // to the second pass, when we know which nmethods survive.
4900 void work_first_pass(uint worker_id) {
4901 // The first nmethods is claimed by the first worker.
4902 if (worker_id == 0 && _first_nmethod != NULL) {
4903 clean_nmethod(_first_nmethod);
4904 _first_nmethod = NULL;
4905 }
4906
4907 int num_claimed_nmethods;
4908 nmethod* claimed_nmethods[MaxClaimNmethods];
4909
4910 while (true) {
4911 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4912
4913 if (num_claimed_nmethods == 0) {
4914 break;
4915 }
4916
4917 for (int i = 0; i < num_claimed_nmethods; i++) {
4918 clean_nmethod(claimed_nmethods[i]);
4919 }
4920 }
4921 }
4922
4923 void work_second_pass(uint worker_id) {
4924 nmethod* nm;
4925 // Take care of postponed nmethods.
4926 while ((nm = claim_postponed_nmethod()) != NULL) {
4927 clean_nmethod_postponed(nm);
4928 }
4929 }
4930 };
4931
4932 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4933
4934 class G1KlassCleaningTask : public StackObj {
4935 BoolObjectClosure* _is_alive;
4936 volatile jint _clean_klass_tree_claimed;
4937 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4938
4939 public:
4940 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4941 _is_alive(is_alive),
4942 _clean_klass_tree_claimed(0),
4943 _klass_iterator() {
4944 }
4945
4946 private:
4947 bool claim_clean_klass_tree_task() {
4948 if (_clean_klass_tree_claimed) {
4949 return false;
4950 }
4951
4952 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4953 }
4954
4955 InstanceKlass* claim_next_klass() {
4956 Klass* klass;
4957 do {
4958 klass =_klass_iterator.next_klass();
4959 } while (klass != NULL && !klass->oop_is_instance());
4960
4961 return (InstanceKlass*)klass;
4962 }
4963
4964 public:
4965
4966 void clean_klass(InstanceKlass* ik) {
4967 ik->clean_implementors_list(_is_alive);
4968 ik->clean_method_data(_is_alive);
4969
4970 // G1 specific cleanup work that has
4971 // been moved here to be done in parallel.
4972 ik->clean_dependent_nmethods();
4973 }
4974
4975 void work() {
4976 ResourceMark rm;
4977
4978 // One worker will clean the subklass/sibling klass tree.
4979 if (claim_clean_klass_tree_task()) {
4980 Klass::clean_subklass_tree(_is_alive);
4981 }
4982
4983 // All workers will help cleaning the classes,
4984 InstanceKlass* klass;
4985 while ((klass = claim_next_klass()) != NULL) {
4986 clean_klass(klass);
4987 }
4988 }
4989 };
4990
4991 // To minimize the remark pause times, the tasks below are done in parallel.
4992 class G1ParallelCleaningTask : public AbstractGangTask {
4993 private:
4994 G1StringSymbolTableUnlinkTask _string_symbol_task;
4995 G1CodeCacheUnloadingTask _code_cache_task;
4996 G1KlassCleaningTask _klass_cleaning_task;
4997
4998 public:
4999 // The constructor is run in the VMThread.
5000 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5001 AbstractGangTask("Parallel Cleaning"),
5002 _string_symbol_task(is_alive, process_strings, process_symbols),
5003 _code_cache_task(num_workers, is_alive, unloading_occurred),
5004 _klass_cleaning_task(is_alive) {
5005 }
5006
5007 // The parallel work done by all worker threads.
5008 void work(uint worker_id) {
5009 // Do first pass of code cache cleaning.
5010 _code_cache_task.work_first_pass(worker_id);
5011
5012 // Let the threads mark that the first pass is done.
5013 _code_cache_task.barrier_mark(worker_id);
5014
5015 // Clean the Strings and Symbols.
5016 _string_symbol_task.work(worker_id);
5017
5018 // Wait for all workers to finish the first code cache cleaning pass.
5019 _code_cache_task.barrier_wait(worker_id);
5020
5021 // Do the second code cache cleaning work, which realize on
5022 // the liveness information gathered during the first pass.
5023 _code_cache_task.work_second_pass(worker_id);
5024
5025 // Clean all klasses that were not unloaded.
5026 _klass_cleaning_task.work();
5027 }
5028 };
5029
5030
5031 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5032 bool process_strings,
5033 bool process_symbols,
5034 bool class_unloading_occurred) {
5035 uint n_workers = workers()->active_workers();
5036
5037 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5038 n_workers, class_unloading_occurred);
5039 workers()->run_task(&g1_unlink_task);
5040 }
5041
5042 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5043 bool process_strings, bool process_symbols) {
5044 {
5045 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5046 workers()->run_task(&g1_unlink_task);
5047 }
5048
5049 if (G1StringDedup::is_enabled()) {
5050 G1StringDedup::unlink(is_alive);
5051 }
5052 }
5053
5054 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5055 private:
5056 DirtyCardQueueSet* _queue;
5057 public:
5058 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5059
5060 virtual void work(uint worker_id) {
5061 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5062 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5063
5064 RedirtyLoggedCardTableEntryClosure cl;
5065 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5066
5067 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5068 }
5069 };
5070
5071 void G1CollectedHeap::redirty_logged_cards() {
5072 double redirty_logged_cards_start = os::elapsedTime();
5073
5074 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5075 dirty_card_queue_set().reset_for_par_iteration();
5076 workers()->run_task(&redirty_task);
5077
5078 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5079 dcq.merge_bufferlists(&dirty_card_queue_set());
5080 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5081
5082 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5083 }
5084
5085 // Weak Reference Processing support
5086
5087 // An always "is_alive" closure that is used to preserve referents.
5088 // If the object is non-null then it's alive. Used in the preservation
5089 // of referent objects that are pointed to by reference objects
5090 // discovered by the CM ref processor.
5091 class G1AlwaysAliveClosure: public BoolObjectClosure {
5092 G1CollectedHeap* _g1;
5093 public:
5094 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5095 bool do_object_b(oop p) {
5096 if (p != NULL) {
5097 return true;
5098 }
5099 return false;
5100 }
5101 };
5102
5103 bool G1STWIsAliveClosure::do_object_b(oop p) {
5104 // An object is reachable if it is outside the collection set,
5105 // or is inside and copied.
5106 return !_g1->obj_in_cs(p) || p->is_forwarded();
5107 }
5108
5109 // Non Copying Keep Alive closure
5110 class G1KeepAliveClosure: public OopClosure {
5111 G1CollectedHeap* _g1;
5112 public:
5113 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5114 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5115 void do_oop(oop* p) {
5116 oop obj = *p;
5117 assert(obj != NULL, "the caller should have filtered out NULL values");
5118
5119 const InCSetState cset_state = _g1->in_cset_state(obj);
5120 if (!cset_state.is_in_cset_or_humongous()) {
5121 return;
5122 }
5123 if (cset_state.is_in_cset()) {
5124 assert( obj->is_forwarded(), "invariant" );
5125 *p = obj->forwardee();
5126 } else {
5127 assert(!obj->is_forwarded(), "invariant" );
5128 assert(cset_state.is_humongous(),
5129 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5130 _g1->set_humongous_is_live(obj);
5131 }
5132 }
5133 };
5134
5135 // Copying Keep Alive closure - can be called from both
5136 // serial and parallel code as long as different worker
5137 // threads utilize different G1ParScanThreadState instances
5138 // and different queues.
5139
5140 class G1CopyingKeepAliveClosure: public OopClosure {
5141 G1CollectedHeap* _g1h;
5142 OopClosure* _copy_non_heap_obj_cl;
5143 G1ParScanThreadState* _par_scan_state;
5144
5145 public:
5146 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5147 OopClosure* non_heap_obj_cl,
5148 G1ParScanThreadState* pss):
5149 _g1h(g1h),
5150 _copy_non_heap_obj_cl(non_heap_obj_cl),
5151 _par_scan_state(pss)
5152 {}
5153
5154 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5155 virtual void do_oop( oop* p) { do_oop_work(p); }
5156
5157 template <class T> void do_oop_work(T* p) {
5158 oop obj = oopDesc::load_decode_heap_oop(p);
5159
5160 if (_g1h->is_in_cset_or_humongous(obj)) {
5161 // If the referent object has been forwarded (either copied
5162 // to a new location or to itself in the event of an
5163 // evacuation failure) then we need to update the reference
5164 // field and, if both reference and referent are in the G1
5165 // heap, update the RSet for the referent.
5166 //
5167 // If the referent has not been forwarded then we have to keep
5168 // it alive by policy. Therefore we have copy the referent.
5169 //
5170 // If the reference field is in the G1 heap then we can push
5171 // on the PSS queue. When the queue is drained (after each
5172 // phase of reference processing) the object and it's followers
5173 // will be copied, the reference field set to point to the
5174 // new location, and the RSet updated. Otherwise we need to
5175 // use the the non-heap or metadata closures directly to copy
5176 // the referent object and update the pointer, while avoiding
5177 // updating the RSet.
5178
5179 if (_g1h->is_in_g1_reserved(p)) {
5180 _par_scan_state->push_on_queue(p);
5181 } else {
5182 assert(!Metaspace::contains((const void*)p),
5183 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5184 _copy_non_heap_obj_cl->do_oop(p);
5185 }
5186 }
5187 }
5188 };
5189
5190 // Serial drain queue closure. Called as the 'complete_gc'
5191 // closure for each discovered list in some of the
5192 // reference processing phases.
5193
5194 class G1STWDrainQueueClosure: public VoidClosure {
5195 protected:
5196 G1CollectedHeap* _g1h;
5197 G1ParScanThreadState* _par_scan_state;
5198
5199 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5200
5201 public:
5202 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5203 _g1h(g1h),
5204 _par_scan_state(pss)
5205 { }
5206
5207 void do_void() {
5208 G1ParScanThreadState* const pss = par_scan_state();
5209 pss->trim_queue();
5210 }
5211 };
5212
5213 // Parallel Reference Processing closures
5214
5215 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5216 // processing during G1 evacuation pauses.
5217
5218 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5219 private:
5220 G1CollectedHeap* _g1h;
5221 RefToScanQueueSet* _queues;
5222 FlexibleWorkGang* _workers;
5223 uint _active_workers;
5224
5225 public:
5226 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5227 FlexibleWorkGang* workers,
5228 RefToScanQueueSet *task_queues,
5229 uint n_workers) :
5230 _g1h(g1h),
5231 _queues(task_queues),
5232 _workers(workers),
5233 _active_workers(n_workers)
5234 {
5235 assert(n_workers > 0, "shouldn't call this otherwise");
5236 }
5237
5238 // Executes the given task using concurrent marking worker threads.
5239 virtual void execute(ProcessTask& task);
5240 virtual void execute(EnqueueTask& task);
5241 };
5242
5243 // Gang task for possibly parallel reference processing
5244
5245 class G1STWRefProcTaskProxy: public AbstractGangTask {
5246 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5247 ProcessTask& _proc_task;
5248 G1CollectedHeap* _g1h;
5249 RefToScanQueueSet *_task_queues;
5250 ParallelTaskTerminator* _terminator;
5251
5252 public:
5253 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5254 G1CollectedHeap* g1h,
5255 RefToScanQueueSet *task_queues,
5256 ParallelTaskTerminator* terminator) :
5257 AbstractGangTask("Process reference objects in parallel"),
5258 _proc_task(proc_task),
5259 _g1h(g1h),
5260 _task_queues(task_queues),
5261 _terminator(terminator)
5262 {}
5263
5264 virtual void work(uint worker_id) {
5265 // The reference processing task executed by a single worker.
5266 ResourceMark rm;
5267 HandleMark hm;
5268
5269 G1STWIsAliveClosure is_alive(_g1h);
5270
5271 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5272 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5273
5274 pss.set_evac_failure_closure(&evac_failure_cl);
5275
5276 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5277
5278 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5279
5280 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5281
5282 if (_g1h->collector_state()->during_initial_mark_pause()) {
5283 // We also need to mark copied objects.
5284 copy_non_heap_cl = ©_mark_non_heap_cl;
5285 }
5286
5287 // Keep alive closure.
5288 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5289
5290 // Complete GC closure
5291 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5292
5293 // Call the reference processing task's work routine.
5294 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5295
5296 // Note we cannot assert that the refs array is empty here as not all
5297 // of the processing tasks (specifically phase2 - pp2_work) execute
5298 // the complete_gc closure (which ordinarily would drain the queue) so
5299 // the queue may not be empty.
5300 }
5301 };
5302
5303 // Driver routine for parallel reference processing.
5304 // Creates an instance of the ref processing gang
5305 // task and has the worker threads execute it.
5306 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5307 assert(_workers != NULL, "Need parallel worker threads.");
5308
5309 ParallelTaskTerminator terminator(_active_workers, _queues);
5310 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5311
5312 _workers->run_task(&proc_task_proxy);
5313 }
5314
5315 // Gang task for parallel reference enqueueing.
5316
5317 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5318 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5319 EnqueueTask& _enq_task;
5320
5321 public:
5322 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5323 AbstractGangTask("Enqueue reference objects in parallel"),
5324 _enq_task(enq_task)
5325 { }
5326
5327 virtual void work(uint worker_id) {
5328 _enq_task.work(worker_id);
5329 }
5330 };
5331
5332 // Driver routine for parallel reference enqueueing.
5333 // Creates an instance of the ref enqueueing gang
5334 // task and has the worker threads execute it.
5335
5336 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5337 assert(_workers != NULL, "Need parallel worker threads.");
5338
5339 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5340
5341 _workers->run_task(&enq_task_proxy);
5342 }
5343
5344 // End of weak reference support closures
5345
5346 // Abstract task used to preserve (i.e. copy) any referent objects
5347 // that are in the collection set and are pointed to by reference
5348 // objects discovered by the CM ref processor.
5349
5350 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5351 protected:
5352 G1CollectedHeap* _g1h;
5353 RefToScanQueueSet *_queues;
5354 ParallelTaskTerminator _terminator;
5355 uint _n_workers;
5356
5357 public:
5358 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5359 AbstractGangTask("ParPreserveCMReferents"),
5360 _g1h(g1h),
5361 _queues(task_queues),
5362 _terminator(workers, _queues),
5363 _n_workers(workers)
5364 { }
5365
5366 void work(uint worker_id) {
5367 ResourceMark rm;
5368 HandleMark hm;
5369
5370 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5371 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5372
5373 pss.set_evac_failure_closure(&evac_failure_cl);
5374
5375 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5376
5377 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5378
5379 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5380
5381 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5382
5383 if (_g1h->collector_state()->during_initial_mark_pause()) {
5384 // We also need to mark copied objects.
5385 copy_non_heap_cl = ©_mark_non_heap_cl;
5386 }
5387
5388 // Is alive closure
5389 G1AlwaysAliveClosure always_alive(_g1h);
5390
5391 // Copying keep alive closure. Applied to referent objects that need
5392 // to be copied.
5393 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5394
5395 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5396
5397 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5398 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5399
5400 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5401 // So this must be true - but assert just in case someone decides to
5402 // change the worker ids.
5403 assert(worker_id < limit, "sanity");
5404 assert(!rp->discovery_is_atomic(), "check this code");
5405
5406 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5407 for (uint idx = worker_id; idx < limit; idx += stride) {
5408 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5409
5410 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5411 while (iter.has_next()) {
5412 // Since discovery is not atomic for the CM ref processor, we
5413 // can see some null referent objects.
5414 iter.load_ptrs(DEBUG_ONLY(true));
5415 oop ref = iter.obj();
5416
5417 // This will filter nulls.
5418 if (iter.is_referent_alive()) {
5419 iter.make_referent_alive();
5420 }
5421 iter.move_to_next();
5422 }
5423 }
5424
5425 // Drain the queue - which may cause stealing
5426 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5427 drain_queue.do_void();
5428 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5429 assert(pss.queue_is_empty(), "should be");
5430 }
5431 };
5432
5433 // Weak Reference processing during an evacuation pause (part 1).
5434 void G1CollectedHeap::process_discovered_references() {
5435 double ref_proc_start = os::elapsedTime();
5436
5437 ReferenceProcessor* rp = _ref_processor_stw;
5438 assert(rp->discovery_enabled(), "should have been enabled");
5439
5440 // Any reference objects, in the collection set, that were 'discovered'
5441 // by the CM ref processor should have already been copied (either by
5442 // applying the external root copy closure to the discovered lists, or
5443 // by following an RSet entry).
5444 //
5445 // But some of the referents, that are in the collection set, that these
5446 // reference objects point to may not have been copied: the STW ref
5447 // processor would have seen that the reference object had already
5448 // been 'discovered' and would have skipped discovering the reference,
5449 // but would not have treated the reference object as a regular oop.
5450 // As a result the copy closure would not have been applied to the
5451 // referent object.
5452 //
5453 // We need to explicitly copy these referent objects - the references
5454 // will be processed at the end of remarking.
5455 //
5456 // We also need to do this copying before we process the reference
5457 // objects discovered by the STW ref processor in case one of these
5458 // referents points to another object which is also referenced by an
5459 // object discovered by the STW ref processor.
5460
5461 uint no_of_gc_workers = workers()->active_workers();
5462
5463 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5464 no_of_gc_workers,
5465 _task_queues);
5466
5467 workers()->run_task(&keep_cm_referents);
5468
5469 // Closure to test whether a referent is alive.
5470 G1STWIsAliveClosure is_alive(this);
5471
5472 // Even when parallel reference processing is enabled, the processing
5473 // of JNI refs is serial and performed serially by the current thread
5474 // rather than by a worker. The following PSS will be used for processing
5475 // JNI refs.
5476
5477 // Use only a single queue for this PSS.
5478 G1ParScanThreadState pss(this, 0, NULL);
5479
5480 // We do not embed a reference processor in the copying/scanning
5481 // closures while we're actually processing the discovered
5482 // reference objects.
5483 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5484
5485 pss.set_evac_failure_closure(&evac_failure_cl);
5486
5487 assert(pss.queue_is_empty(), "pre-condition");
5488
5489 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5490
5491 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5492
5493 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5494
5495 if (collector_state()->during_initial_mark_pause()) {
5496 // We also need to mark copied objects.
5497 copy_non_heap_cl = ©_mark_non_heap_cl;
5498 }
5499
5500 // Keep alive closure.
5501 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5502
5503 // Serial Complete GC closure
5504 G1STWDrainQueueClosure drain_queue(this, &pss);
5505
5506 // Setup the soft refs policy...
5507 rp->setup_policy(false);
5508
5509 ReferenceProcessorStats stats;
5510 if (!rp->processing_is_mt()) {
5511 // Serial reference processing...
5512 stats = rp->process_discovered_references(&is_alive,
5513 &keep_alive,
5514 &drain_queue,
5515 NULL,
5516 _gc_timer_stw,
5517 _gc_tracer_stw->gc_id());
5518 } else {
5519 // Parallel reference processing
5520 assert(rp->num_q() == no_of_gc_workers, "sanity");
5521 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5522
5523 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5524 stats = rp->process_discovered_references(&is_alive,
5525 &keep_alive,
5526 &drain_queue,
5527 &par_task_executor,
5528 _gc_timer_stw,
5529 _gc_tracer_stw->gc_id());
5530 }
5531
5532 _gc_tracer_stw->report_gc_reference_stats(stats);
5533
5534 // We have completed copying any necessary live referent objects.
5535 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5536
5537 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5538 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5539 }
5540
5541 // Weak Reference processing during an evacuation pause (part 2).
5542 void G1CollectedHeap::enqueue_discovered_references() {
5543 double ref_enq_start = os::elapsedTime();
5544
5545 ReferenceProcessor* rp = _ref_processor_stw;
5546 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5547
5548 // Now enqueue any remaining on the discovered lists on to
5549 // the pending list.
5550 if (!rp->processing_is_mt()) {
5551 // Serial reference processing...
5552 rp->enqueue_discovered_references();
5553 } else {
5554 // Parallel reference enqueueing
5555
5556 uint n_workers = workers()->active_workers();
5557
5558 assert(rp->num_q() == n_workers, "sanity");
5559 assert(n_workers <= rp->max_num_q(), "sanity");
5560
5561 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5562 rp->enqueue_discovered_references(&par_task_executor);
5563 }
5564
5565 rp->verify_no_references_recorded();
5566 assert(!rp->discovery_enabled(), "should have been disabled");
5567
5568 // FIXME
5569 // CM's reference processing also cleans up the string and symbol tables.
5570 // Should we do that here also? We could, but it is a serial operation
5571 // and could significantly increase the pause time.
5572
5573 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5574 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5575 }
5576
5577 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5578 _expand_heap_after_alloc_failure = true;
5579 _evacuation_failed = false;
5580
5581 // Should G1EvacuationFailureALot be in effect for this GC?
5582 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5583
5584 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5585
5586 // Disable the hot card cache.
5587 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5588 hot_card_cache->reset_hot_cache_claimed_index();
5589 hot_card_cache->set_use_cache(false);
5590
5591 const uint n_workers = workers()->active_workers();
5592
5593 init_for_evac_failure(NULL);
5594
5595 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5596 double start_par_time_sec = os::elapsedTime();
5597 double end_par_time_sec;
5598
5599 {
5600 G1RootProcessor root_processor(this, n_workers);
5601 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5602 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5603 if (collector_state()->during_initial_mark_pause()) {
5604 ClassLoaderDataGraph::clear_claimed_marks();
5605 }
5606
5607 // The individual threads will set their evac-failure closures.
5608 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5609
5610 workers()->run_task(&g1_par_task);
5611 end_par_time_sec = os::elapsedTime();
5612
5613 // Closing the inner scope will execute the destructor
5614 // for the G1RootProcessor object. We record the current
5615 // elapsed time before closing the scope so that time
5616 // taken for the destructor is NOT included in the
5617 // reported parallel time.
5618 }
5619
5620 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5621
5622 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5623 phase_times->record_par_time(par_time_ms);
5624
5625 double code_root_fixup_time_ms =
5626 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5627 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5628
5629 // Process any discovered reference objects - we have
5630 // to do this _before_ we retire the GC alloc regions
5631 // as we may have to copy some 'reachable' referent
5632 // objects (and their reachable sub-graphs) that were
5633 // not copied during the pause.
5634 process_discovered_references();
5635
5636 if (G1StringDedup::is_enabled()) {
5637 double fixup_start = os::elapsedTime();
5638
5639 G1STWIsAliveClosure is_alive(this);
5640 G1KeepAliveClosure keep_alive(this);
5641 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5642
5643 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5644 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5645 }
5646
5647 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5648 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5649
5650 // Reset and re-enable the hot card cache.
5651 // Note the counts for the cards in the regions in the
5652 // collection set are reset when the collection set is freed.
5653 hot_card_cache->reset_hot_cache();
5654 hot_card_cache->set_use_cache(true);
5655
5656 purge_code_root_memory();
5657
5658 finalize_for_evac_failure();
5659
5660 if (evacuation_failed()) {
5661 remove_self_forwarding_pointers();
5662
5663 // Reset the G1EvacuationFailureALot counters and flags
5664 // Note: the values are reset only when an actual
5665 // evacuation failure occurs.
5666 NOT_PRODUCT(reset_evacuation_should_fail();)
5667 }
5668
5669 // Enqueue any remaining references remaining on the STW
5670 // reference processor's discovered lists. We need to do
5671 // this after the card table is cleaned (and verified) as
5672 // the act of enqueueing entries on to the pending list
5673 // will log these updates (and dirty their associated
5674 // cards). We need these updates logged to update any
5675 // RSets.
5676 enqueue_discovered_references();
5677
5678 redirty_logged_cards();
5679 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5680 }
5681
5682 void G1CollectedHeap::free_region(HeapRegion* hr,
5683 FreeRegionList* free_list,
5684 bool par,
5685 bool locked) {
5686 assert(!hr->is_free(), "the region should not be free");
5687 assert(!hr->is_empty(), "the region should not be empty");
5688 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5689 assert(free_list != NULL, "pre-condition");
5690
5691 if (G1VerifyBitmaps) {
5692 MemRegion mr(hr->bottom(), hr->end());
5693 concurrent_mark()->clearRangePrevBitmap(mr);
5694 }
5695
5696 // Clear the card counts for this region.
5697 // Note: we only need to do this if the region is not young
5698 // (since we don't refine cards in young regions).
5699 if (!hr->is_young()) {
5700 _cg1r->hot_card_cache()->reset_card_counts(hr);
5701 }
5702 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5703 free_list->add_ordered(hr);
5704 }
5705
5706 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5707 FreeRegionList* free_list,
5708 bool par) {
5709 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5710 assert(free_list != NULL, "pre-condition");
5711
5712 size_t hr_capacity = hr->capacity();
5713 // We need to read this before we make the region non-humongous,
5714 // otherwise the information will be gone.
5715 uint last_index = hr->last_hc_index();
5716 hr->clear_humongous();
5717 free_region(hr, free_list, par);
5718
5719 uint i = hr->hrm_index() + 1;
5720 while (i < last_index) {
5721 HeapRegion* curr_hr = region_at(i);
5722 assert(curr_hr->is_continues_humongous(), "invariant");
5723 curr_hr->clear_humongous();
5724 free_region(curr_hr, free_list, par);
5725 i += 1;
5726 }
5727 }
5728
5729 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5730 const HeapRegionSetCount& humongous_regions_removed) {
5731 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5732 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5733 _old_set.bulk_remove(old_regions_removed);
5734 _humongous_set.bulk_remove(humongous_regions_removed);
5735 }
5736
5737 }
5738
5739 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5740 assert(list != NULL, "list can't be null");
5741 if (!list->is_empty()) {
5742 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5743 _hrm.insert_list_into_free_list(list);
5744 }
5745 }
5746
5747 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5748 _allocator->decrease_used(bytes);
5749 }
5750
5751 class G1ParCleanupCTTask : public AbstractGangTask {
5752 G1SATBCardTableModRefBS* _ct_bs;
5753 G1CollectedHeap* _g1h;
5754 HeapRegion* volatile _su_head;
5755 public:
5756 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5757 G1CollectedHeap* g1h) :
5758 AbstractGangTask("G1 Par Cleanup CT Task"),
5759 _ct_bs(ct_bs), _g1h(g1h) { }
5760
5761 void work(uint worker_id) {
5762 HeapRegion* r;
5763 while (r = _g1h->pop_dirty_cards_region()) {
5764 clear_cards(r);
5765 }
5766 }
5767
5768 void clear_cards(HeapRegion* r) {
5769 // Cards of the survivors should have already been dirtied.
5770 if (!r->is_survivor()) {
5771 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5772 }
5773 }
5774 };
5775
5776 #ifndef PRODUCT
5777 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5778 G1CollectedHeap* _g1h;
5779 G1SATBCardTableModRefBS* _ct_bs;
5780 public:
5781 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5782 : _g1h(g1h), _ct_bs(ct_bs) { }
5783 virtual bool doHeapRegion(HeapRegion* r) {
5784 if (r->is_survivor()) {
5785 _g1h->verify_dirty_region(r);
5786 } else {
5787 _g1h->verify_not_dirty_region(r);
5788 }
5789 return false;
5790 }
5791 };
5792
5793 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5794 // All of the region should be clean.
5795 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5796 MemRegion mr(hr->bottom(), hr->end());
5797 ct_bs->verify_not_dirty_region(mr);
5798 }
5799
5800 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5801 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5802 // dirty allocated blocks as they allocate them. The thread that
5803 // retires each region and replaces it with a new one will do a
5804 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5805 // not dirty that area (one less thing to have to do while holding
5806 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5807 // is dirty.
5808 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5809 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5810 if (hr->is_young()) {
5811 ct_bs->verify_g1_young_region(mr);
5812 } else {
5813 ct_bs->verify_dirty_region(mr);
5814 }
5815 }
5816
5817 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5818 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5819 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5820 verify_dirty_region(hr);
5821 }
5822 }
5823
5824 void G1CollectedHeap::verify_dirty_young_regions() {
5825 verify_dirty_young_list(_young_list->first_region());
5826 }
5827
5828 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5829 HeapWord* tams, HeapWord* end) {
5830 guarantee(tams <= end,
5831 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5832 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5833 if (result < end) {
5834 gclog_or_tty->cr();
5835 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5836 bitmap_name, p2i(result));
5837 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5838 bitmap_name, p2i(tams), p2i(end));
5839 return false;
5840 }
5841 return true;
5842 }
5843
5844 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5845 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5846 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5847
5848 HeapWord* bottom = hr->bottom();
5849 HeapWord* ptams = hr->prev_top_at_mark_start();
5850 HeapWord* ntams = hr->next_top_at_mark_start();
5851 HeapWord* end = hr->end();
5852
5853 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5854
5855 bool res_n = true;
5856 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5857 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5858 // if we happen to be in that state.
5859 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5860 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5861 }
5862 if (!res_p || !res_n) {
5863 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5864 HR_FORMAT_PARAMS(hr));
5865 gclog_or_tty->print_cr("#### Caller: %s", caller);
5866 return false;
5867 }
5868 return true;
5869 }
5870
5871 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5872 if (!G1VerifyBitmaps) return;
5873
5874 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5875 }
5876
5877 class G1VerifyBitmapClosure : public HeapRegionClosure {
5878 private:
5879 const char* _caller;
5880 G1CollectedHeap* _g1h;
5881 bool _failures;
5882
5883 public:
5884 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5885 _caller(caller), _g1h(g1h), _failures(false) { }
5886
5887 bool failures() { return _failures; }
5888
5889 virtual bool doHeapRegion(HeapRegion* hr) {
5890 if (hr->is_continues_humongous()) return false;
5891
5892 bool result = _g1h->verify_bitmaps(_caller, hr);
5893 if (!result) {
5894 _failures = true;
5895 }
5896 return false;
5897 }
5898 };
5899
5900 void G1CollectedHeap::check_bitmaps(const char* caller) {
5901 if (!G1VerifyBitmaps) return;
5902
5903 G1VerifyBitmapClosure cl(caller, this);
5904 heap_region_iterate(&cl);
5905 guarantee(!cl.failures(), "bitmap verification");
5906 }
5907
5908 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5909 private:
5910 bool _failures;
5911 public:
5912 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5913
5914 virtual bool doHeapRegion(HeapRegion* hr) {
5915 uint i = hr->hrm_index();
5916 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5917 if (hr->is_humongous()) {
5918 if (hr->in_collection_set()) {
5919 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5920 _failures = true;
5921 return true;
5922 }
5923 if (cset_state.is_in_cset()) {
5924 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5925 _failures = true;
5926 return true;
5927 }
5928 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5929 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5930 _failures = true;
5931 return true;
5932 }
5933 } else {
5934 if (cset_state.is_humongous()) {
5935 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5936 _failures = true;
5937 return true;
5938 }
5939 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5940 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5941 hr->in_collection_set(), cset_state.value(), i);
5942 _failures = true;
5943 return true;
5944 }
5945 if (cset_state.is_in_cset()) {
5946 if (hr->is_young() != (cset_state.is_young())) {
5947 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5948 hr->is_young(), cset_state.value(), i);
5949 _failures = true;
5950 return true;
5951 }
5952 if (hr->is_old() != (cset_state.is_old())) {
5953 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5954 hr->is_old(), cset_state.value(), i);
5955 _failures = true;
5956 return true;
5957 }
5958 }
5959 }
5960 return false;
5961 }
5962
5963 bool failures() const { return _failures; }
5964 };
5965
5966 bool G1CollectedHeap::check_cset_fast_test() {
5967 G1CheckCSetFastTableClosure cl;
5968 _hrm.iterate(&cl);
5969 return !cl.failures();
5970 }
5971 #endif // PRODUCT
5972
5973 void G1CollectedHeap::cleanUpCardTable() {
5974 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5975 double start = os::elapsedTime();
5976
5977 {
5978 // Iterate over the dirty cards region list.
5979 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5980
5981 workers()->run_task(&cleanup_task);
5982 #ifndef PRODUCT
5983 if (G1VerifyCTCleanup || VerifyAfterGC) {
5984 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5985 heap_region_iterate(&cleanup_verifier);
5986 }
5987 #endif
5988 }
5989
5990 double elapsed = os::elapsedTime() - start;
5991 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5992 }
5993
5994 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5995 size_t pre_used = 0;
5996 FreeRegionList local_free_list("Local List for CSet Freeing");
5997
5998 double young_time_ms = 0.0;
5999 double non_young_time_ms = 0.0;
6000
6001 // Since the collection set is a superset of the the young list,
6002 // all we need to do to clear the young list is clear its
6003 // head and length, and unlink any young regions in the code below
6004 _young_list->clear();
6005
6006 G1CollectorPolicy* policy = g1_policy();
6007
6008 double start_sec = os::elapsedTime();
6009 bool non_young = true;
6010
6011 HeapRegion* cur = cs_head;
6012 int age_bound = -1;
6013 size_t rs_lengths = 0;
6014
6015 while (cur != NULL) {
6016 assert(!is_on_master_free_list(cur), "sanity");
6017 if (non_young) {
6018 if (cur->is_young()) {
6019 double end_sec = os::elapsedTime();
6020 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6021 non_young_time_ms += elapsed_ms;
6022
6023 start_sec = os::elapsedTime();
6024 non_young = false;
6025 }
6026 } else {
6027 if (!cur->is_young()) {
6028 double end_sec = os::elapsedTime();
6029 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6030 young_time_ms += elapsed_ms;
6031
6032 start_sec = os::elapsedTime();
6033 non_young = true;
6034 }
6035 }
6036
6037 rs_lengths += cur->rem_set()->occupied_locked();
6038
6039 HeapRegion* next = cur->next_in_collection_set();
6040 assert(cur->in_collection_set(), "bad CS");
6041 cur->set_next_in_collection_set(NULL);
6042 clear_in_cset(cur);
6043
6044 if (cur->is_young()) {
6045 int index = cur->young_index_in_cset();
6046 assert(index != -1, "invariant");
6047 assert((uint) index < policy->young_cset_region_length(), "invariant");
6048 size_t words_survived = _surviving_young_words[index];
6049 cur->record_surv_words_in_group(words_survived);
6050
6051 // At this point the we have 'popped' cur from the collection set
6052 // (linked via next_in_collection_set()) but it is still in the
6053 // young list (linked via next_young_region()). Clear the
6054 // _next_young_region field.
6055 cur->set_next_young_region(NULL);
6056 } else {
6057 int index = cur->young_index_in_cset();
6058 assert(index == -1, "invariant");
6059 }
6060
6061 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6062 (!cur->is_young() && cur->young_index_in_cset() == -1),
6063 "invariant" );
6064
6065 if (!cur->evacuation_failed()) {
6066 MemRegion used_mr = cur->used_region();
6067
6068 // And the region is empty.
6069 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6070 pre_used += cur->used();
6071 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6072 } else {
6073 cur->uninstall_surv_rate_group();
6074 if (cur->is_young()) {
6075 cur->set_young_index_in_cset(-1);
6076 }
6077 cur->set_evacuation_failed(false);
6078 // The region is now considered to be old.
6079 cur->set_old();
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 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6326 _young_list->push_region(hr);
6327 }
6328
6329 class NoYoungRegionsClosure: public HeapRegionClosure {
6330 private:
6331 bool _success;
6332 public:
6333 NoYoungRegionsClosure() : _success(true) { }
6334 bool doHeapRegion(HeapRegion* r) {
6335 if (r->is_young()) {
6336 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6337 p2i(r->bottom()), p2i(r->end()));
6338 _success = false;
6339 }
6340 return false;
6341 }
6342 bool success() { return _success; }
6343 };
6344
6345 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6346 bool ret = _young_list->check_list_empty(check_sample);
6347
6348 if (check_heap) {
6349 NoYoungRegionsClosure closure;
6350 heap_region_iterate(&closure);
6351 ret = ret && closure.success();
6352 }
6353
6354 return ret;
6355 }
6356
6357 class TearDownRegionSetsClosure : public HeapRegionClosure {
6358 private:
6359 HeapRegionSet *_old_set;
6360
6361 public:
6362 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6363
6364 bool doHeapRegion(HeapRegion* r) {
6365 if (r->is_old()) {
6366 _old_set->remove(r);
6367 } else {
6368 // We ignore free regions, we'll empty the free list afterwards.
6369 // We ignore young regions, we'll empty the young list afterwards.
6370 // We ignore humongous regions, we're not tearing down the
6371 // humongous regions set.
6372 assert(r->is_free() || r->is_young() || r->is_humongous(),
6373 "it cannot be another type");
6374 }
6375 return false;
6376 }
6377
6378 ~TearDownRegionSetsClosure() {
6379 assert(_old_set->is_empty(), "post-condition");
6380 }
6381 };
6382
6383 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6384 assert_at_safepoint(true /* should_be_vm_thread */);
6385
6386 if (!free_list_only) {
6387 TearDownRegionSetsClosure cl(&_old_set);
6388 heap_region_iterate(&cl);
6389
6390 // Note that emptying the _young_list is postponed and instead done as
6391 // the first step when rebuilding the regions sets again. The reason for
6392 // this is that during a full GC string deduplication needs to know if
6393 // a collected region was young or old when the full GC was initiated.
6394 }
6395 _hrm.remove_all_free_regions();
6396 }
6397
6398 class RebuildRegionSetsClosure : public HeapRegionClosure {
6399 private:
6400 bool _free_list_only;
6401 HeapRegionSet* _old_set;
6402 HeapRegionManager* _hrm;
6403 size_t _total_used;
6404
6405 public:
6406 RebuildRegionSetsClosure(bool free_list_only,
6407 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6408 _free_list_only(free_list_only),
6409 _old_set(old_set), _hrm(hrm), _total_used(0) {
6410 assert(_hrm->num_free_regions() == 0, "pre-condition");
6411 if (!free_list_only) {
6412 assert(_old_set->is_empty(), "pre-condition");
6413 }
6414 }
6415
6416 bool doHeapRegion(HeapRegion* r) {
6417 if (r->is_continues_humongous()) {
6418 return false;
6419 }
6420
6421 if (r->is_empty()) {
6422 // Add free regions to the free list
6423 r->set_free();
6424 r->set_allocation_context(AllocationContext::system());
6425 _hrm->insert_into_free_list(r);
6426 } else if (!_free_list_only) {
6427 assert(!r->is_young(), "we should not come across young regions");
6428
6429 if (r->is_humongous()) {
6430 // We ignore humongous regions. We left the humongous set unchanged.
6431 } else {
6432 // Objects that were compacted would have ended up on regions
6433 // that were previously old or free. Archive regions (which are
6434 // old) will not have been touched.
6435 assert(r->is_free() || r->is_old(), "invariant");
6436 // We now consider them old, so register as such. Leave
6437 // archive regions set that way, however, while still adding
6438 // them to the old set.
6439 if (!r->is_archive()) {
6440 r->set_old();
6441 }
6442 _old_set->add(r);
6443 }
6444 _total_used += r->used();
6445 }
6446
6447 return false;
6448 }
6449
6450 size_t total_used() {
6451 return _total_used;
6452 }
6453 };
6454
6455 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6456 assert_at_safepoint(true /* should_be_vm_thread */);
6457
6458 if (!free_list_only) {
6459 _young_list->empty_list();
6460 }
6461
6462 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6463 heap_region_iterate(&cl);
6464
6465 if (!free_list_only) {
6466 _allocator->set_used(cl.total_used());
6467 if (_archive_allocator != NULL) {
6468 _archive_allocator->clear_used();
6469 }
6470 }
6471 assert(_allocator->used_unlocked() == recalculate_used(),
6472 err_msg("inconsistent _allocator->used_unlocked(), "
6473 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6474 _allocator->used_unlocked(), recalculate_used()));
6475 }
6476
6477 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6478 _refine_cte_cl->set_concurrent(concurrent);
6479 }
6480
6481 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6482 HeapRegion* hr = heap_region_containing(p);
6483 return hr->is_in(p);
6484 }
6485
6486 // Methods for the mutator alloc region
6487
6488 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6489 bool force) {
6490 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6491 assert(!force || g1_policy()->can_expand_young_list(),
6492 "if force is true we should be able to expand the young list");
6493 bool young_list_full = g1_policy()->is_young_list_full();
6494 if (force || !young_list_full) {
6495 HeapRegion* new_alloc_region = new_region(word_size,
6496 false /* is_old */,
6497 false /* do_expand */);
6498 if (new_alloc_region != NULL) {
6499 set_region_short_lived_locked(new_alloc_region);
6500 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6501 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6502 return new_alloc_region;
6503 }
6504 }
6505 return NULL;
6506 }
6507
6508 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6509 size_t allocated_bytes) {
6510 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6511 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6512
6513 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6514 _allocator->increase_used(allocated_bytes);
6515 _hr_printer.retire(alloc_region);
6516 // We update the eden sizes here, when the region is retired,
6517 // instead of when it's allocated, since this is the point that its
6518 // used space has been recored in _summary_bytes_used.
6519 g1mm()->update_eden_size();
6520 }
6521
6522 // Methods for the GC alloc regions
6523
6524 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6525 uint count,
6526 InCSetState dest) {
6527 assert(FreeList_lock->owned_by_self(), "pre-condition");
6528
6529 if (count < g1_policy()->max_regions(dest)) {
6530 const bool is_survivor = (dest.is_young());
6531 HeapRegion* new_alloc_region = new_region(word_size,
6532 !is_survivor,
6533 true /* do_expand */);
6534 if (new_alloc_region != NULL) {
6535 // We really only need to do this for old regions given that we
6536 // should never scan survivors. But it doesn't hurt to do it
6537 // for survivors too.
6538 new_alloc_region->record_timestamp();
6539 if (is_survivor) {
6540 new_alloc_region->set_survivor();
6541 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6542 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6543 } else {
6544 new_alloc_region->set_old();
6545 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6546 check_bitmaps("Old Region Allocation", new_alloc_region);
6547 }
6548 bool during_im = collector_state()->during_initial_mark_pause();
6549 new_alloc_region->note_start_of_copying(during_im);
6550 return new_alloc_region;
6551 }
6552 }
6553 return NULL;
6554 }
6555
6556 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6557 size_t allocated_bytes,
6558 InCSetState dest) {
6559 bool during_im = collector_state()->during_initial_mark_pause();
6560 alloc_region->note_end_of_copying(during_im);
6561 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6562 if (dest.is_young()) {
6563 young_list()->add_survivor_region(alloc_region);
6564 } else {
6565 _old_set.add(alloc_region);
6566 }
6567 _hr_printer.retire(alloc_region);
6568 }
6569
6570 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6571 bool expanded = false;
6572 uint index = _hrm.find_highest_free(&expanded);
6573
6574 if (index != G1_NO_HRM_INDEX) {
6575 if (expanded) {
6576 ergo_verbose1(ErgoHeapSizing,
6577 "attempt heap expansion",
6578 ergo_format_reason("requested address range outside heap bounds")
6579 ergo_format_byte("region size"),
6580 HeapRegion::GrainWords * HeapWordSize);
6581 }
6582 _hrm.allocate_free_regions_starting_at(index, 1);
6583 return region_at(index);
6584 }
6585 return NULL;
6586 }
6587
6588
6589 // Heap region set verification
6590
6591 class VerifyRegionListsClosure : public HeapRegionClosure {
6592 private:
6593 HeapRegionSet* _old_set;
6594 HeapRegionSet* _humongous_set;
6595 HeapRegionManager* _hrm;
6596
6597 public:
6598 HeapRegionSetCount _old_count;
6599 HeapRegionSetCount _humongous_count;
6600 HeapRegionSetCount _free_count;
6601
6602 VerifyRegionListsClosure(HeapRegionSet* old_set,
6603 HeapRegionSet* humongous_set,
6604 HeapRegionManager* hrm) :
6605 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6606 _old_count(), _humongous_count(), _free_count(){ }
6607
6608 bool doHeapRegion(HeapRegion* hr) {
6609 if (hr->is_continues_humongous()) {
6610 return false;
6611 }
6612
6613 if (hr->is_young()) {
6614 // TODO
6615 } else if (hr->is_starts_humongous()) {
6616 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6617 _humongous_count.increment(1u, hr->capacity());
6618 } else if (hr->is_empty()) {
6619 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6620 _free_count.increment(1u, hr->capacity());
6621 } else if (hr->is_old()) {
6622 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6623 _old_count.increment(1u, hr->capacity());
6624 } else {
6625 // There are no other valid region types. Check for one invalid
6626 // one we can identify: pinned without old or humongous set.
6627 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6628 ShouldNotReachHere();
6629 }
6630 return false;
6631 }
6632
6633 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6634 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6635 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6636 old_set->total_capacity_bytes(), _old_count.capacity()));
6637
6638 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6639 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6640 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6641
6642 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()));
6643 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6644 free_list->total_capacity_bytes(), _free_count.capacity()));
6645 }
6646 };
6647
6648 void G1CollectedHeap::verify_region_sets() {
6649 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6650
6651 // First, check the explicit lists.
6652 _hrm.verify();
6653 {
6654 // Given that a concurrent operation might be adding regions to
6655 // the secondary free list we have to take the lock before
6656 // verifying it.
6657 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6658 _secondary_free_list.verify_list();
6659 }
6660
6661 // If a concurrent region freeing operation is in progress it will
6662 // be difficult to correctly attributed any free regions we come
6663 // across to the correct free list given that they might belong to
6664 // one of several (free_list, secondary_free_list, any local lists,
6665 // etc.). So, if that's the case we will skip the rest of the
6666 // verification operation. Alternatively, waiting for the concurrent
6667 // operation to complete will have a non-trivial effect on the GC's
6668 // operation (no concurrent operation will last longer than the
6669 // interval between two calls to verification) and it might hide
6670 // any issues that we would like to catch during testing.
6671 if (free_regions_coming()) {
6672 return;
6673 }
6674
6675 // Make sure we append the secondary_free_list on the free_list so
6676 // that all free regions we will come across can be safely
6677 // attributed to the free_list.
6678 append_secondary_free_list_if_not_empty_with_lock();
6679
6680 // Finally, make sure that the region accounting in the lists is
6681 // consistent with what we see in the heap.
6682
6683 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6684 heap_region_iterate(&cl);
6685 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6686 }
6687
6688 // Optimized nmethod scanning
6689
6690 class RegisterNMethodOopClosure: public OopClosure {
6691 G1CollectedHeap* _g1h;
6692 nmethod* _nm;
6693
6694 template <class T> void do_oop_work(T* p) {
6695 T heap_oop = oopDesc::load_heap_oop(p);
6696 if (!oopDesc::is_null(heap_oop)) {
6697 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6698 HeapRegion* hr = _g1h->heap_region_containing(obj);
6699 assert(!hr->is_continues_humongous(),
6700 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6701 " starting at "HR_FORMAT,
6702 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6703
6704 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6705 hr->add_strong_code_root_locked(_nm);
6706 }
6707 }
6708
6709 public:
6710 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6711 _g1h(g1h), _nm(nm) {}
6712
6713 void do_oop(oop* p) { do_oop_work(p); }
6714 void do_oop(narrowOop* p) { do_oop_work(p); }
6715 };
6716
6717 class UnregisterNMethodOopClosure: public OopClosure {
6718 G1CollectedHeap* _g1h;
6719 nmethod* _nm;
6720
6721 template <class T> void do_oop_work(T* p) {
6722 T heap_oop = oopDesc::load_heap_oop(p);
6723 if (!oopDesc::is_null(heap_oop)) {
6724 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6725 HeapRegion* hr = _g1h->heap_region_containing(obj);
6726 assert(!hr->is_continues_humongous(),
6727 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6728 " starting at "HR_FORMAT,
6729 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6730
6731 hr->remove_strong_code_root(_nm);
6732 }
6733 }
6734
6735 public:
6736 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6737 _g1h(g1h), _nm(nm) {}
6738
6739 void do_oop(oop* p) { do_oop_work(p); }
6740 void do_oop(narrowOop* p) { do_oop_work(p); }
6741 };
6742
6743 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6744 CollectedHeap::register_nmethod(nm);
6745
6746 guarantee(nm != NULL, "sanity");
6747 RegisterNMethodOopClosure reg_cl(this, nm);
6748 nm->oops_do(®_cl);
6749 }
6750
6751 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6752 CollectedHeap::unregister_nmethod(nm);
6753
6754 guarantee(nm != NULL, "sanity");
6755 UnregisterNMethodOopClosure reg_cl(this, nm);
6756 nm->oops_do(®_cl, true);
6757 }
6758
6759 void G1CollectedHeap::purge_code_root_memory() {
6760 double purge_start = os::elapsedTime();
6761 G1CodeRootSet::purge();
6762 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6763 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6764 }
6765
6766 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6767 G1CollectedHeap* _g1h;
6768
6769 public:
6770 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6771 _g1h(g1h) {}
6772
6773 void do_code_blob(CodeBlob* cb) {
6774 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6775 if (nm == NULL) {
6776 return;
6777 }
6778
6779 if (ScavengeRootsInCode) {
6780 _g1h->register_nmethod(nm);
6781 }
6782 }
6783 };
6784
6785 void G1CollectedHeap::rebuild_strong_code_roots() {
6786 RebuildStrongCodeRootClosure blob_cl(this);
6787 CodeCache::blobs_do(&blob_cl);
6788 }