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