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