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 #if defined(COMPILER2) || INCLUDE_JVMCI
1440 DerivedPointerTable::clear();
1441 #endif
1442
1443 // Disable discovery and empty the discovered lists
1444 // for the CM ref processor.
1445 ref_processor_cm()->disable_discovery();
1446 ref_processor_cm()->abandon_partial_discovery();
1447 ref_processor_cm()->verify_no_references_recorded();
1448
1449 // Abandon current iterations of concurrent marking and concurrent
1450 // refinement, if any are in progress. We have to do this before
1451 // wait_until_scan_finished() below.
1452 concurrent_mark()->abort();
1453
1454 // Make sure we'll choose a new allocation region afterwards.
1455 _allocator->release_mutator_alloc_region();
1456 _allocator->abandon_gc_alloc_regions();
1457 g1_rem_set()->cleanupHRRS();
1458
1459 // We should call this after we retire any currently active alloc
1460 // regions so that all the ALLOC / RETIRE events are generated
1461 // before the start GC event.
1462 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1463
1464 // We may have added regions to the current incremental collection
1465 // set between the last GC or pause and now. We need to clear the
1466 // incremental collection set and then start rebuilding it afresh
1467 // after this full GC.
1468 abandon_collection_set(g1_policy()->inc_cset_head());
1469 g1_policy()->clear_incremental_cset();
1470 g1_policy()->stop_incremental_cset_building();
1471
1472 tear_down_region_sets(false /* free_list_only */);
1473 collector_state()->set_gcs_are_young(true);
1474
1475 // See the comments in g1CollectedHeap.hpp and
1476 // G1CollectedHeap::ref_processing_init() about
1477 // how reference processing currently works in G1.
1478
1479 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1480 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1481
1482 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1483 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1484
1485 ref_processor_stw()->enable_discovery();
1486 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1487
1488 // Do collection work
1489 {
1490 HandleMark hm; // Discard invalid handles created during gc
1491 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1492 }
1493
1494 assert(num_free_regions() == 0, "we should not have added any free regions");
1495 rebuild_region_sets(false /* free_list_only */);
1496
1497 // Enqueue any discovered reference objects that have
1498 // not been removed from the discovered lists.
1499 ref_processor_stw()->enqueue_discovered_references();
1500
1501 #if defined(COMPILER2) || INCLUDE_JVMCI
1502 DerivedPointerTable::update_pointers();
1503 #endif
1504
1505 MemoryService::track_memory_usage();
1506
1507 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1508 ref_processor_stw()->verify_no_references_recorded();
1509
1510 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1511 ClassLoaderDataGraph::purge();
1512 MetaspaceAux::verify_metrics();
1513
1514 // Note: since we've just done a full GC, concurrent
1515 // marking is no longer active. Therefore we need not
1516 // re-enable reference discovery for the CM ref processor.
1517 // That will be done at the start of the next marking cycle.
1518 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1519 ref_processor_cm()->verify_no_references_recorded();
1520
1521 reset_gc_time_stamp();
1522 // Since everything potentially moved, we will clear all remembered
1523 // sets, and clear all cards. Later we will rebuild remembered
1524 // sets. We will also reset the GC time stamps of the regions.
1525 clear_rsets_post_compaction();
1526 check_gc_time_stamps();
1527
1528 // Resize the heap if necessary.
1529 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1530
1531 if (_hr_printer.is_active()) {
1532 // We should do this after we potentially resize the heap so
1533 // that all the COMMIT / UNCOMMIT events are generated before
1534 // the end GC event.
1535
1536 print_hrm_post_compaction();
1537 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1538 }
1539
1540 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1541 if (hot_card_cache->use_cache()) {
1542 hot_card_cache->reset_card_counts();
1543 hot_card_cache->reset_hot_cache();
1544 }
1545
1546 // Rebuild remembered sets of all regions.
1547 uint n_workers =
1548 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1549 workers()->active_workers(),
1550 Threads::number_of_non_daemon_threads());
1551 workers()->set_active_workers(n_workers);
1552
1553 ParRebuildRSTask rebuild_rs_task(this);
1554 workers()->run_task(&rebuild_rs_task);
1555
1556 // Rebuild the strong code root lists for each region
1557 rebuild_strong_code_roots();
1558
1559 if (true) { // FIXME
1560 MetaspaceGC::compute_new_size();
1561 }
1562
1563 #ifdef TRACESPINNING
1564 ParallelTaskTerminator::print_termination_counts();
1565 #endif
1566
1567 // Discard all rset updates
1568 JavaThread::dirty_card_queue_set().abandon_logs();
1569 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1570
1571 _young_list->reset_sampled_info();
1572 // At this point there should be no regions in the
1573 // entire heap tagged as young.
1574 assert(check_young_list_empty(true /* check_heap */),
1575 "young list should be empty at this point");
1576
1577 // Update the number of full collections that have been completed.
1578 increment_old_marking_cycles_completed(false /* concurrent */);
1579
1580 _hrm.verify_optional();
1581 verify_region_sets_optional();
1582
1583 verify_after_gc();
1584
1585 // Clear the previous marking bitmap, if needed for bitmap verification.
1586 // Note we cannot do this when we clear the next marking bitmap in
1587 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1588 // objects marked during a full GC against the previous bitmap.
1589 // But we need to clear it before calling check_bitmaps below since
1590 // the full GC has compacted objects and updated TAMS but not updated
1591 // the prev bitmap.
1592 if (G1VerifyBitmaps) {
1593 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1594 }
1595 check_bitmaps("Full GC End");
1596
1597 // Start a new incremental collection set for the next pause
1598 assert(g1_policy()->collection_set() == NULL, "must be");
1599 g1_policy()->start_incremental_cset_building();
1600
1601 clear_cset_fast_test();
1602
1603 _allocator->init_mutator_alloc_region();
1604
1605 g1_policy()->record_full_collection_end();
1606
1607 if (G1Log::fine()) {
1608 g1_policy()->print_heap_transition();
1609 }
1610
1611 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1612 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1613 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1614 // before any GC notifications are raised.
1615 g1mm()->update_sizes();
1616
1617 gc_epilogue(true);
1618 }
1619
1620 if (G1Log::finer()) {
1621 g1_policy()->print_detailed_heap_transition(true /* full */);
1622 }
1623
1624 print_heap_after_gc();
1625 trace_heap_after_gc(gc_tracer);
1626
1627 post_full_gc_dump(gc_timer);
1628
1629 gc_timer->register_gc_end();
1630 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1631 }
1632
1633 return true;
1634 }
1635
1636 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1637 // do_collection() will return whether it succeeded in performing
1638 // the GC. Currently, there is no facility on the
1639 // do_full_collection() API to notify the caller than the collection
1640 // did not succeed (e.g., because it was locked out by the GC
1641 // locker). So, right now, we'll ignore the return value.
1642 bool dummy = do_collection(true, /* explicit_gc */
1643 clear_all_soft_refs,
1644 0 /* word_size */);
1645 }
1646
1647 // This code is mostly copied from TenuredGeneration.
1648 void
1649 G1CollectedHeap::
1650 resize_if_necessary_after_full_collection(size_t word_size) {
1651 // Include the current allocation, if any, and bytes that will be
1652 // pre-allocated to support collections, as "used".
1653 const size_t used_after_gc = used();
1654 const size_t capacity_after_gc = capacity();
1655 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1656
1657 // This is enforced in arguments.cpp.
1658 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1659 "otherwise the code below doesn't make sense");
1660
1661 // We don't have floating point command-line arguments
1662 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1663 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1664 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1665 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1666
1667 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1668 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1669
1670 // We have to be careful here as these two calculations can overflow
1671 // 32-bit size_t's.
1672 double used_after_gc_d = (double) used_after_gc;
1673 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1674 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1675
1676 // Let's make sure that they are both under the max heap size, which
1677 // by default will make them fit into a size_t.
1678 double desired_capacity_upper_bound = (double) max_heap_size;
1679 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1680 desired_capacity_upper_bound);
1681 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1682 desired_capacity_upper_bound);
1683
1684 // We can now safely turn them into size_t's.
1685 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1686 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1687
1688 // This assert only makes sense here, before we adjust them
1689 // with respect to the min and max heap size.
1690 assert(minimum_desired_capacity <= maximum_desired_capacity,
1691 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1692 "maximum_desired_capacity = " SIZE_FORMAT,
1693 minimum_desired_capacity, maximum_desired_capacity));
1694
1695 // Should not be greater than the heap max size. No need to adjust
1696 // it with respect to the heap min size as it's a lower bound (i.e.,
1697 // we'll try to make the capacity larger than it, not smaller).
1698 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1699 // Should not be less than the heap min size. No need to adjust it
1700 // with respect to the heap max size as it's an upper bound (i.e.,
1701 // we'll try to make the capacity smaller than it, not greater).
1702 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1703
1704 if (capacity_after_gc < minimum_desired_capacity) {
1705 // Don't expand unless it's significant
1706 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1707 ergo_verbose4(ErgoHeapSizing,
1708 "attempt heap expansion",
1709 ergo_format_reason("capacity lower than "
1710 "min desired capacity after Full GC")
1711 ergo_format_byte("capacity")
1712 ergo_format_byte("occupancy")
1713 ergo_format_byte_perc("min desired capacity"),
1714 capacity_after_gc, used_after_gc,
1715 minimum_desired_capacity, (double) MinHeapFreeRatio);
1716 expand(expand_bytes);
1717
1718 // No expansion, now see if we want to shrink
1719 } else if (capacity_after_gc > maximum_desired_capacity) {
1720 // Capacity too large, compute shrinking size
1721 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1722 ergo_verbose4(ErgoHeapSizing,
1723 "attempt heap shrinking",
1724 ergo_format_reason("capacity higher than "
1725 "max desired capacity after Full GC")
1726 ergo_format_byte("capacity")
1727 ergo_format_byte("occupancy")
1728 ergo_format_byte_perc("max desired capacity"),
1729 capacity_after_gc, used_after_gc,
1730 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1731 shrink(shrink_bytes);
1732 }
1733 }
1734
1735
1736 HeapWord*
1737 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1738 AllocationContext_t context,
1739 bool* succeeded) {
1740 assert_at_safepoint(true /* should_be_vm_thread */);
1741
1742 *succeeded = true;
1743 // Let's attempt the allocation first.
1744 HeapWord* result =
1745 attempt_allocation_at_safepoint(word_size,
1746 context,
1747 false /* expect_null_mutator_alloc_region */);
1748 if (result != NULL) {
1749 assert(*succeeded, "sanity");
1750 return result;
1751 }
1752
1753 // In a G1 heap, we're supposed to keep allocation from failing by
1754 // incremental pauses. Therefore, at least for now, we'll favor
1755 // expansion over collection. (This might change in the future if we can
1756 // do something smarter than full collection to satisfy a failed alloc.)
1757 result = expand_and_allocate(word_size, context);
1758 if (result != NULL) {
1759 assert(*succeeded, "sanity");
1760 return result;
1761 }
1762
1763 // Expansion didn't work, we'll try to do a Full GC.
1764 bool gc_succeeded = do_collection(false, /* explicit_gc */
1765 false, /* clear_all_soft_refs */
1766 word_size);
1767 if (!gc_succeeded) {
1768 *succeeded = false;
1769 return NULL;
1770 }
1771
1772 // Retry the allocation
1773 result = attempt_allocation_at_safepoint(word_size,
1774 context,
1775 true /* expect_null_mutator_alloc_region */);
1776 if (result != NULL) {
1777 assert(*succeeded, "sanity");
1778 return result;
1779 }
1780
1781 // Then, try a Full GC that will collect all soft references.
1782 gc_succeeded = do_collection(false, /* explicit_gc */
1783 true, /* clear_all_soft_refs */
1784 word_size);
1785 if (!gc_succeeded) {
1786 *succeeded = false;
1787 return NULL;
1788 }
1789
1790 // Retry the allocation once more
1791 result = attempt_allocation_at_safepoint(word_size,
1792 context,
1793 true /* expect_null_mutator_alloc_region */);
1794 if (result != NULL) {
1795 assert(*succeeded, "sanity");
1796 return result;
1797 }
1798
1799 assert(!collector_policy()->should_clear_all_soft_refs(),
1800 "Flag should have been handled and cleared prior to this point");
1801
1802 // What else? We might try synchronous finalization later. If the total
1803 // space available is large enough for the allocation, then a more
1804 // complete compaction phase than we've tried so far might be
1805 // appropriate.
1806 assert(*succeeded, "sanity");
1807 return NULL;
1808 }
1809
1810 // Attempting to expand the heap sufficiently
1811 // to support an allocation of the given "word_size". If
1812 // successful, perform the allocation and return the address of the
1813 // allocated block, or else "NULL".
1814
1815 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1816 assert_at_safepoint(true /* should_be_vm_thread */);
1817
1818 verify_region_sets_optional();
1819
1820 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1821 ergo_verbose1(ErgoHeapSizing,
1822 "attempt heap expansion",
1823 ergo_format_reason("allocation request failed")
1824 ergo_format_byte("allocation request"),
1825 word_size * HeapWordSize);
1826 if (expand(expand_bytes)) {
1827 _hrm.verify_optional();
1828 verify_region_sets_optional();
1829 return attempt_allocation_at_safepoint(word_size,
1830 context,
1831 false /* expect_null_mutator_alloc_region */);
1832 }
1833 return NULL;
1834 }
1835
1836 bool G1CollectedHeap::expand(size_t expand_bytes) {
1837 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1838 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1839 HeapRegion::GrainBytes);
1840 ergo_verbose2(ErgoHeapSizing,
1841 "expand the heap",
1842 ergo_format_byte("requested expansion amount")
1843 ergo_format_byte("attempted expansion amount"),
1844 expand_bytes, aligned_expand_bytes);
1845
1846 if (is_maximal_no_gc()) {
1847 ergo_verbose0(ErgoHeapSizing,
1848 "did not expand the heap",
1849 ergo_format_reason("heap already fully expanded"));
1850 return false;
1851 }
1852
1853 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1854 assert(regions_to_expand > 0, "Must expand by at least one region");
1855
1856 uint expanded_by = _hrm.expand_by(regions_to_expand);
1857
1858 if (expanded_by > 0) {
1859 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1860 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1861 g1_policy()->record_new_heap_size(num_regions());
1862 } else {
1863 ergo_verbose0(ErgoHeapSizing,
1864 "did not expand the heap",
1865 ergo_format_reason("heap expansion operation failed"));
1866 // The expansion of the virtual storage space was unsuccessful.
1867 // Let's see if it was because we ran out of swap.
1868 if (G1ExitOnExpansionFailure &&
1869 _hrm.available() >= regions_to_expand) {
1870 // We had head room...
1871 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1872 }
1873 }
1874 return regions_to_expand > 0;
1875 }
1876
1877 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1878 size_t aligned_shrink_bytes =
1879 ReservedSpace::page_align_size_down(shrink_bytes);
1880 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1881 HeapRegion::GrainBytes);
1882 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1883
1884 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1885 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1886
1887 ergo_verbose3(ErgoHeapSizing,
1888 "shrink the heap",
1889 ergo_format_byte("requested shrinking amount")
1890 ergo_format_byte("aligned shrinking amount")
1891 ergo_format_byte("attempted shrinking amount"),
1892 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1893 if (num_regions_removed > 0) {
1894 g1_policy()->record_new_heap_size(num_regions());
1895 } else {
1896 ergo_verbose0(ErgoHeapSizing,
1897 "did not shrink the heap",
1898 ergo_format_reason("heap shrinking operation failed"));
1899 }
1900 }
1901
1902 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1903 verify_region_sets_optional();
1904
1905 // We should only reach here at the end of a Full GC which means we
1906 // should not not be holding to any GC alloc regions. The method
1907 // below will make sure of that and do any remaining clean up.
1908 _allocator->abandon_gc_alloc_regions();
1909
1910 // Instead of tearing down / rebuilding the free lists here, we
1911 // could instead use the remove_all_pending() method on free_list to
1912 // remove only the ones that we need to remove.
1913 tear_down_region_sets(true /* free_list_only */);
1914 shrink_helper(shrink_bytes);
1915 rebuild_region_sets(true /* free_list_only */);
1916
1917 _hrm.verify_optional();
1918 verify_region_sets_optional();
1919 }
1920
1921 // Public methods.
1922
1923 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1924 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1925 #endif // _MSC_VER
1926
1927
1928 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1929 CollectedHeap(),
1930 _g1_policy(policy_),
1931 _dirty_card_queue_set(false),
1932 _into_cset_dirty_card_queue_set(false),
1933 _is_alive_closure_cm(this),
1934 _is_alive_closure_stw(this),
1935 _ref_processor_cm(NULL),
1936 _ref_processor_stw(NULL),
1937 _bot_shared(NULL),
1938 _cg1r(NULL),
1939 _g1mm(NULL),
1940 _refine_cte_cl(NULL),
1941 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1942 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1943 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1944 _humongous_reclaim_candidates(),
1945 _has_humongous_reclaim_candidates(false),
1946 _archive_allocator(NULL),
1947 _free_regions_coming(false),
1948 _young_list(new YoungList(this)),
1949 _gc_time_stamp(0),
1950 _summary_bytes_used(0),
1951 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1952 _old_evac_stats(OldPLABSize, PLABWeight),
1953 _expand_heap_after_alloc_failure(true),
1954 _surviving_young_words(NULL),
1955 _old_marking_cycles_started(0),
1956 _old_marking_cycles_completed(0),
1957 _heap_summary_sent(false),
1958 _in_cset_fast_test(),
1959 _dirty_cards_region_list(NULL),
1960 _worker_cset_start_region(NULL),
1961 _worker_cset_start_region_time_stamp(NULL),
1962 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1963 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1964 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1965 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1966
1967 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1968 /* are_GC_task_threads */true,
1969 /* are_ConcurrentGC_threads */false);
1970 _workers->initialize_workers();
1971
1972 _allocator = G1Allocator::create_allocator(this);
1973 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1974
1975 // Override the default _filler_array_max_size so that no humongous filler
1976 // objects are created.
1977 _filler_array_max_size = _humongous_object_threshold_in_words;
1978
1979 uint n_queues = ParallelGCThreads;
1980 _task_queues = new RefToScanQueueSet(n_queues);
1981
1982 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1983 assert(n_rem_sets > 0, "Invariant.");
1984
1985 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1986 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1987 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1988
1989 for (uint i = 0; i < n_queues; i++) {
1990 RefToScanQueue* q = new RefToScanQueue();
1991 q->initialize();
1992 _task_queues->register_queue(i, q);
1993 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1994 }
1995 clear_cset_start_regions();
1996
1997 // Initialize the G1EvacuationFailureALot counters and flags.
1998 NOT_PRODUCT(reset_evacuation_should_fail();)
1999
2000 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2001 }
2002
2003 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2004 size_t size,
2005 size_t translation_factor) {
2006 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2007 // Allocate a new reserved space, preferring to use large pages.
2008 ReservedSpace rs(size, preferred_page_size);
2009 G1RegionToSpaceMapper* result =
2010 G1RegionToSpaceMapper::create_mapper(rs,
2011 size,
2012 rs.alignment(),
2013 HeapRegion::GrainBytes,
2014 translation_factor,
2015 mtGC);
2016 if (TracePageSizes) {
2017 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2018 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2019 }
2020 return result;
2021 }
2022
2023 jint G1CollectedHeap::initialize() {
2024 CollectedHeap::pre_initialize();
2025 os::enable_vtime();
2026
2027 G1Log::init();
2028
2029 // Necessary to satisfy locking discipline assertions.
2030
2031 MutexLocker x(Heap_lock);
2032
2033 // We have to initialize the printer before committing the heap, as
2034 // it will be used then.
2035 _hr_printer.set_active(G1PrintHeapRegions);
2036
2037 // While there are no constraints in the GC code that HeapWordSize
2038 // be any particular value, there are multiple other areas in the
2039 // system which believe this to be true (e.g. oop->object_size in some
2040 // cases incorrectly returns the size in wordSize units rather than
2041 // HeapWordSize).
2042 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2043
2044 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2045 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2046 size_t heap_alignment = collector_policy()->heap_alignment();
2047
2048 // Ensure that the sizes are properly aligned.
2049 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2050 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2051 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2052
2053 _refine_cte_cl = new RefineCardTableEntryClosure();
2054
2055 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2056
2057 // Reserve the maximum.
2058
2059 // When compressed oops are enabled, the preferred heap base
2060 // is calculated by subtracting the requested size from the
2061 // 32Gb boundary and using the result as the base address for
2062 // heap reservation. If the requested size is not aligned to
2063 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2064 // into the ReservedHeapSpace constructor) then the actual
2065 // base of the reserved heap may end up differing from the
2066 // address that was requested (i.e. the preferred heap base).
2067 // If this happens then we could end up using a non-optimal
2068 // compressed oops mode.
2069
2070 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2071 heap_alignment);
2072
2073 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2074
2075 // Create the barrier set for the entire reserved region.
2076 G1SATBCardTableLoggingModRefBS* bs
2077 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2078 bs->initialize();
2079 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2080 set_barrier_set(bs);
2081
2082 // Also create a G1 rem set.
2083 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2084
2085 // Carve out the G1 part of the heap.
2086
2087 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2088 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2089 G1RegionToSpaceMapper* heap_storage =
2090 G1RegionToSpaceMapper::create_mapper(g1_rs,
2091 g1_rs.size(),
2092 page_size,
2093 HeapRegion::GrainBytes,
2094 1,
2095 mtJavaHeap);
2096 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2097 max_byte_size, page_size,
2098 heap_rs.base(),
2099 heap_rs.size());
2100 heap_storage->set_mapping_changed_listener(&_listener);
2101
2102 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2103 G1RegionToSpaceMapper* bot_storage =
2104 create_aux_memory_mapper("Block offset table",
2105 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2106 G1BlockOffsetSharedArray::heap_map_factor());
2107
2108 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2109 G1RegionToSpaceMapper* cardtable_storage =
2110 create_aux_memory_mapper("Card table",
2111 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2112 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2113
2114 G1RegionToSpaceMapper* card_counts_storage =
2115 create_aux_memory_mapper("Card counts table",
2116 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2117 G1CardCounts::heap_map_factor());
2118
2119 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2120 G1RegionToSpaceMapper* prev_bitmap_storage =
2121 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2122 G1RegionToSpaceMapper* next_bitmap_storage =
2123 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2124
2125 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2126 g1_barrier_set()->initialize(cardtable_storage);
2127 // Do later initialization work for concurrent refinement.
2128 _cg1r->init(card_counts_storage);
2129
2130 // 6843694 - ensure that the maximum region index can fit
2131 // in the remembered set structures.
2132 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2133 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2134
2135 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2136 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2137 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2138 "too many cards per region");
2139
2140 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2141
2142 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2143
2144 {
2145 HeapWord* start = _hrm.reserved().start();
2146 HeapWord* end = _hrm.reserved().end();
2147 size_t granularity = HeapRegion::GrainBytes;
2148
2149 _in_cset_fast_test.initialize(start, end, granularity);
2150 _humongous_reclaim_candidates.initialize(start, end, granularity);
2151 }
2152
2153 // Create the ConcurrentMark data structure and thread.
2154 // (Must do this late, so that "max_regions" is defined.)
2155 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2156 if (_cm == NULL || !_cm->completed_initialization()) {
2157 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2158 return JNI_ENOMEM;
2159 }
2160 _cmThread = _cm->cmThread();
2161
2162 // Initialize the from_card cache structure of HeapRegionRemSet.
2163 HeapRegionRemSet::init_heap(max_regions());
2164
2165 // Now expand into the initial heap size.
2166 if (!expand(init_byte_size)) {
2167 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2168 return JNI_ENOMEM;
2169 }
2170
2171 // Perform any initialization actions delegated to the policy.
2172 g1_policy()->init();
2173
2174 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2175 SATB_Q_FL_lock,
2176 G1SATBProcessCompletedThreshold,
2177 Shared_SATB_Q_lock);
2178
2179 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2180 DirtyCardQ_CBL_mon,
2181 DirtyCardQ_FL_lock,
2182 concurrent_g1_refine()->yellow_zone(),
2183 concurrent_g1_refine()->red_zone(),
2184 Shared_DirtyCardQ_lock);
2185
2186 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2187 DirtyCardQ_CBL_mon,
2188 DirtyCardQ_FL_lock,
2189 -1, // never trigger processing
2190 -1, // no limit on length
2191 Shared_DirtyCardQ_lock,
2192 &JavaThread::dirty_card_queue_set());
2193
2194 // Initialize the card queue set used to hold cards containing
2195 // references into the collection set.
2196 _into_cset_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 // Here we allocate the dummy HeapRegion that is required by the
2205 // G1AllocRegion class.
2206 HeapRegion* dummy_region = _hrm.get_dummy_region();
2207
2208 // We'll re-use the same region whether the alloc region will
2209 // require BOT updates or not and, if it doesn't, then a non-young
2210 // region will complain that it cannot support allocations without
2211 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2212 dummy_region->set_eden();
2213 // Make sure it's full.
2214 dummy_region->set_top(dummy_region->end());
2215 G1AllocRegion::setup(this, dummy_region);
2216
2217 _allocator->init_mutator_alloc_region();
2218
2219 // Do create of the monitoring and management support so that
2220 // values in the heap have been properly initialized.
2221 _g1mm = new G1MonitoringSupport(this);
2222
2223 G1StringDedup::initialize();
2224
2225 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2226 for (uint i = 0; i < ParallelGCThreads; i++) {
2227 new (&_preserved_objs[i]) OopAndMarkOopStack();
2228 }
2229
2230 return JNI_OK;
2231 }
2232
2233 void G1CollectedHeap::stop() {
2234 // Stop all concurrent threads. We do this to make sure these threads
2235 // do not continue to execute and access resources (e.g. gclog_or_tty)
2236 // that are destroyed during shutdown.
2237 _cg1r->stop();
2238 _cmThread->stop();
2239 if (G1StringDedup::is_enabled()) {
2240 G1StringDedup::stop();
2241 }
2242 }
2243
2244 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2245 return HeapRegion::max_region_size();
2246 }
2247
2248 void G1CollectedHeap::post_initialize() {
2249 CollectedHeap::post_initialize();
2250 ref_processing_init();
2251 }
2252
2253 void G1CollectedHeap::ref_processing_init() {
2254 // Reference processing in G1 currently works as follows:
2255 //
2256 // * There are two reference processor instances. One is
2257 // used to record and process discovered references
2258 // during concurrent marking; the other is used to
2259 // record and process references during STW pauses
2260 // (both full and incremental).
2261 // * Both ref processors need to 'span' the entire heap as
2262 // the regions in the collection set may be dotted around.
2263 //
2264 // * For the concurrent marking ref processor:
2265 // * Reference discovery is enabled at initial marking.
2266 // * Reference discovery is disabled and the discovered
2267 // references processed etc during remarking.
2268 // * Reference discovery is MT (see below).
2269 // * Reference discovery requires a barrier (see below).
2270 // * Reference processing may or may not be MT
2271 // (depending on the value of ParallelRefProcEnabled
2272 // and ParallelGCThreads).
2273 // * A full GC disables reference discovery by the CM
2274 // ref processor and abandons any entries on it's
2275 // discovered lists.
2276 //
2277 // * For the STW processor:
2278 // * Non MT discovery is enabled at the start of a full GC.
2279 // * Processing and enqueueing during a full GC is non-MT.
2280 // * During a full GC, references are processed after marking.
2281 //
2282 // * Discovery (may or may not be MT) is enabled at the start
2283 // of an incremental evacuation pause.
2284 // * References are processed near the end of a STW evacuation pause.
2285 // * For both types of GC:
2286 // * Discovery is atomic - i.e. not concurrent.
2287 // * Reference discovery will not need a barrier.
2288
2289 MemRegion mr = reserved_region();
2290
2291 // Concurrent Mark ref processor
2292 _ref_processor_cm =
2293 new ReferenceProcessor(mr, // span
2294 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2295 // mt processing
2296 ParallelGCThreads,
2297 // degree of mt processing
2298 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2299 // mt discovery
2300 MAX2(ParallelGCThreads, ConcGCThreads),
2301 // degree of mt discovery
2302 false,
2303 // Reference discovery is not atomic
2304 &_is_alive_closure_cm);
2305 // is alive closure
2306 // (for efficiency/performance)
2307
2308 // STW ref processor
2309 _ref_processor_stw =
2310 new ReferenceProcessor(mr, // span
2311 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2312 // mt processing
2313 ParallelGCThreads,
2314 // degree of mt processing
2315 (ParallelGCThreads > 1),
2316 // mt discovery
2317 ParallelGCThreads,
2318 // degree of mt discovery
2319 true,
2320 // Reference discovery is atomic
2321 &_is_alive_closure_stw);
2322 // is alive closure
2323 // (for efficiency/performance)
2324 }
2325
2326 size_t G1CollectedHeap::capacity() const {
2327 return _hrm.length() * HeapRegion::GrainBytes;
2328 }
2329
2330 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2331 assert(!hr->is_continues_humongous(), "pre-condition");
2332 hr->reset_gc_time_stamp();
2333 if (hr->is_starts_humongous()) {
2334 uint first_index = hr->hrm_index() + 1;
2335 uint last_index = hr->last_hc_index();
2336 for (uint i = first_index; i < last_index; i += 1) {
2337 HeapRegion* chr = region_at(i);
2338 assert(chr->is_continues_humongous(), "sanity");
2339 chr->reset_gc_time_stamp();
2340 }
2341 }
2342 }
2343
2344 #ifndef PRODUCT
2345
2346 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2347 private:
2348 unsigned _gc_time_stamp;
2349 bool _failures;
2350
2351 public:
2352 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2353 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2354
2355 virtual bool doHeapRegion(HeapRegion* hr) {
2356 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2357 if (_gc_time_stamp != region_gc_time_stamp) {
2358 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2359 "expected %d", HR_FORMAT_PARAMS(hr),
2360 region_gc_time_stamp, _gc_time_stamp);
2361 _failures = true;
2362 }
2363 return false;
2364 }
2365
2366 bool failures() { return _failures; }
2367 };
2368
2369 void G1CollectedHeap::check_gc_time_stamps() {
2370 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2371 heap_region_iterate(&cl);
2372 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2373 }
2374 #endif // PRODUCT
2375
2376 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2377 DirtyCardQueue* into_cset_dcq,
2378 bool concurrent,
2379 uint worker_i) {
2380 // Clean cards in the hot card cache
2381 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2382 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2383
2384 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2385 size_t n_completed_buffers = 0;
2386 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2387 n_completed_buffers++;
2388 }
2389 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2390 dcqs.clear_n_completed_buffers();
2391 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2392 }
2393
2394 // Computes the sum of the storage used by the various regions.
2395 size_t G1CollectedHeap::used() const {
2396 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2397 if (_archive_allocator != NULL) {
2398 result += _archive_allocator->used();
2399 }
2400 return result;
2401 }
2402
2403 size_t G1CollectedHeap::used_unlocked() const {
2404 return _summary_bytes_used;
2405 }
2406
2407 class SumUsedClosure: public HeapRegionClosure {
2408 size_t _used;
2409 public:
2410 SumUsedClosure() : _used(0) {}
2411 bool doHeapRegion(HeapRegion* r) {
2412 if (!r->is_continues_humongous()) {
2413 _used += r->used();
2414 }
2415 return false;
2416 }
2417 size_t result() { return _used; }
2418 };
2419
2420 size_t G1CollectedHeap::recalculate_used() const {
2421 double recalculate_used_start = os::elapsedTime();
2422
2423 SumUsedClosure blk;
2424 heap_region_iterate(&blk);
2425
2426 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2427 return blk.result();
2428 }
2429
2430 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2431 switch (cause) {
2432 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2433 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2434 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2435 case GCCause::_g1_humongous_allocation: return true;
2436 case GCCause::_update_allocation_context_stats_inc: return true;
2437 case GCCause::_wb_conc_mark: return true;
2438 default: return false;
2439 }
2440 }
2441
2442 #ifndef PRODUCT
2443 void G1CollectedHeap::allocate_dummy_regions() {
2444 // Let's fill up most of the region
2445 size_t word_size = HeapRegion::GrainWords - 1024;
2446 // And as a result the region we'll allocate will be humongous.
2447 guarantee(is_humongous(word_size), "sanity");
2448
2449 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2450 // Let's use the existing mechanism for the allocation
2451 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2452 AllocationContext::system());
2453 if (dummy_obj != NULL) {
2454 MemRegion mr(dummy_obj, word_size);
2455 CollectedHeap::fill_with_object(mr);
2456 } else {
2457 // If we can't allocate once, we probably cannot allocate
2458 // again. Let's get out of the loop.
2459 break;
2460 }
2461 }
2462 }
2463 #endif // !PRODUCT
2464
2465 void G1CollectedHeap::increment_old_marking_cycles_started() {
2466 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2467 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2468 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2469 _old_marking_cycles_started, _old_marking_cycles_completed));
2470
2471 _old_marking_cycles_started++;
2472 }
2473
2474 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2475 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2476
2477 // We assume that if concurrent == true, then the caller is a
2478 // concurrent thread that was joined the Suspendible Thread
2479 // Set. If there's ever a cheap way to check this, we should add an
2480 // assert here.
2481
2482 // Given that this method is called at the end of a Full GC or of a
2483 // concurrent cycle, and those can be nested (i.e., a Full GC can
2484 // interrupt a concurrent cycle), the number of full collections
2485 // completed should be either one (in the case where there was no
2486 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2487 // behind the number of full collections started.
2488
2489 // This is the case for the inner caller, i.e. a Full GC.
2490 assert(concurrent ||
2491 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2492 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2493 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2494 "is inconsistent with _old_marking_cycles_completed = %u",
2495 _old_marking_cycles_started, _old_marking_cycles_completed));
2496
2497 // This is the case for the outer caller, i.e. the concurrent cycle.
2498 assert(!concurrent ||
2499 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2500 err_msg("for outer caller (concurrent cycle): "
2501 "_old_marking_cycles_started = %u "
2502 "is inconsistent with _old_marking_cycles_completed = %u",
2503 _old_marking_cycles_started, _old_marking_cycles_completed));
2504
2505 _old_marking_cycles_completed += 1;
2506
2507 // We need to clear the "in_progress" flag in the CM thread before
2508 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2509 // is set) so that if a waiter requests another System.gc() it doesn't
2510 // incorrectly see that a marking cycle is still in progress.
2511 if (concurrent) {
2512 _cmThread->set_idle();
2513 }
2514
2515 // This notify_all() will ensure that a thread that called
2516 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2517 // and it's waiting for a full GC to finish will be woken up. It is
2518 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2519 FullGCCount_lock->notify_all();
2520 }
2521
2522 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2523 collector_state()->set_concurrent_cycle_started(true);
2524 _gc_timer_cm->register_gc_start(start_time);
2525
2526 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2527 trace_heap_before_gc(_gc_tracer_cm);
2528 }
2529
2530 void G1CollectedHeap::register_concurrent_cycle_end() {
2531 if (collector_state()->concurrent_cycle_started()) {
2532 if (_cm->has_aborted()) {
2533 _gc_tracer_cm->report_concurrent_mode_failure();
2534 }
2535
2536 _gc_timer_cm->register_gc_end();
2537 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2538
2539 // Clear state variables to prepare for the next concurrent cycle.
2540 collector_state()->set_concurrent_cycle_started(false);
2541 _heap_summary_sent = false;
2542 }
2543 }
2544
2545 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2546 if (collector_state()->concurrent_cycle_started()) {
2547 // This function can be called when:
2548 // the cleanup pause is run
2549 // the concurrent cycle is aborted before the cleanup pause.
2550 // the concurrent cycle is aborted after the cleanup pause,
2551 // but before the concurrent cycle end has been registered.
2552 // Make sure that we only send the heap information once.
2553 if (!_heap_summary_sent) {
2554 trace_heap_after_gc(_gc_tracer_cm);
2555 _heap_summary_sent = true;
2556 }
2557 }
2558 }
2559
2560 void G1CollectedHeap::collect(GCCause::Cause cause) {
2561 assert_heap_not_locked();
2562
2563 uint gc_count_before;
2564 uint old_marking_count_before;
2565 uint full_gc_count_before;
2566 bool retry_gc;
2567
2568 do {
2569 retry_gc = false;
2570
2571 {
2572 MutexLocker ml(Heap_lock);
2573
2574 // Read the GC count while holding the Heap_lock
2575 gc_count_before = total_collections();
2576 full_gc_count_before = total_full_collections();
2577 old_marking_count_before = _old_marking_cycles_started;
2578 }
2579
2580 if (should_do_concurrent_full_gc(cause)) {
2581 // Schedule an initial-mark evacuation pause that will start a
2582 // concurrent cycle. We're setting word_size to 0 which means that
2583 // we are not requesting a post-GC allocation.
2584 VM_G1IncCollectionPause op(gc_count_before,
2585 0, /* word_size */
2586 true, /* should_initiate_conc_mark */
2587 g1_policy()->max_pause_time_ms(),
2588 cause);
2589 op.set_allocation_context(AllocationContext::current());
2590
2591 VMThread::execute(&op);
2592 if (!op.pause_succeeded()) {
2593 if (old_marking_count_before == _old_marking_cycles_started) {
2594 retry_gc = op.should_retry_gc();
2595 } else {
2596 // A Full GC happened while we were trying to schedule the
2597 // initial-mark GC. No point in starting a new cycle given
2598 // that the whole heap was collected anyway.
2599 }
2600
2601 if (retry_gc) {
2602 if (GC_locker::is_active_and_needs_gc()) {
2603 GC_locker::stall_until_clear();
2604 }
2605 }
2606 }
2607 } else {
2608 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2609 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2610
2611 // Schedule a standard evacuation pause. We're setting word_size
2612 // to 0 which means that we are not requesting a post-GC allocation.
2613 VM_G1IncCollectionPause op(gc_count_before,
2614 0, /* word_size */
2615 false, /* should_initiate_conc_mark */
2616 g1_policy()->max_pause_time_ms(),
2617 cause);
2618 VMThread::execute(&op);
2619 } else {
2620 // Schedule a Full GC.
2621 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2622 VMThread::execute(&op);
2623 }
2624 }
2625 } while (retry_gc);
2626 }
2627
2628 bool G1CollectedHeap::is_in(const void* p) const {
2629 if (_hrm.reserved().contains(p)) {
2630 // Given that we know that p is in the reserved space,
2631 // heap_region_containing_raw() should successfully
2632 // return the containing region.
2633 HeapRegion* hr = heap_region_containing_raw(p);
2634 return hr->is_in(p);
2635 } else {
2636 return false;
2637 }
2638 }
2639
2640 #ifdef ASSERT
2641 bool G1CollectedHeap::is_in_exact(const void* p) const {
2642 bool contains = reserved_region().contains(p);
2643 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2644 if (contains && available) {
2645 return true;
2646 } else {
2647 return false;
2648 }
2649 }
2650 #endif
2651
2652 bool G1CollectedHeap::obj_in_cs(oop obj) {
2653 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2654 return r != NULL && r->in_collection_set();
2655 }
2656
2657 // Iteration functions.
2658
2659 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2660
2661 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2662 ExtendedOopClosure* _cl;
2663 public:
2664 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2665 bool doHeapRegion(HeapRegion* r) {
2666 if (!r->is_continues_humongous()) {
2667 r->oop_iterate(_cl);
2668 }
2669 return false;
2670 }
2671 };
2672
2673 // Iterates an ObjectClosure over all objects within a HeapRegion.
2674
2675 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2676 ObjectClosure* _cl;
2677 public:
2678 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2679 bool doHeapRegion(HeapRegion* r) {
2680 if (!r->is_continues_humongous()) {
2681 r->object_iterate(_cl);
2682 }
2683 return false;
2684 }
2685 };
2686
2687 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2688 IterateObjectClosureRegionClosure blk(cl);
2689 heap_region_iterate(&blk);
2690 }
2691
2692 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2693 _hrm.iterate(cl);
2694 }
2695
2696 void
2697 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2698 uint worker_id,
2699 HeapRegionClaimer *hrclaimer,
2700 bool concurrent) const {
2701 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2702 }
2703
2704 // Clear the cached CSet starting regions and (more importantly)
2705 // the time stamps. Called when we reset the GC time stamp.
2706 void G1CollectedHeap::clear_cset_start_regions() {
2707 assert(_worker_cset_start_region != NULL, "sanity");
2708 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2709
2710 for (uint i = 0; i < ParallelGCThreads; i++) {
2711 _worker_cset_start_region[i] = NULL;
2712 _worker_cset_start_region_time_stamp[i] = 0;
2713 }
2714 }
2715
2716 // Given the id of a worker, obtain or calculate a suitable
2717 // starting region for iterating over the current collection set.
2718 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2719 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2720
2721 HeapRegion* result = NULL;
2722 unsigned gc_time_stamp = get_gc_time_stamp();
2723
2724 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2725 // Cached starting region for current worker was set
2726 // during the current pause - so it's valid.
2727 // Note: the cached starting heap region may be NULL
2728 // (when the collection set is empty).
2729 result = _worker_cset_start_region[worker_i];
2730 assert(result == NULL || result->in_collection_set(), "sanity");
2731 return result;
2732 }
2733
2734 // The cached entry was not valid so let's calculate
2735 // a suitable starting heap region for this worker.
2736
2737 // We want the parallel threads to start their collection
2738 // set iteration at different collection set regions to
2739 // avoid contention.
2740 // If we have:
2741 // n collection set regions
2742 // p threads
2743 // Then thread t will start at region floor ((t * n) / p)
2744
2745 result = g1_policy()->collection_set();
2746 uint cs_size = g1_policy()->cset_region_length();
2747 uint active_workers = workers()->active_workers();
2748
2749 uint end_ind = (cs_size * worker_i) / active_workers;
2750 uint start_ind = 0;
2751
2752 if (worker_i > 0 &&
2753 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2754 // Previous workers starting region is valid
2755 // so let's iterate from there
2756 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2757 result = _worker_cset_start_region[worker_i - 1];
2758 }
2759
2760 for (uint i = start_ind; i < end_ind; i++) {
2761 result = result->next_in_collection_set();
2762 }
2763
2764 // Note: the calculated starting heap region may be NULL
2765 // (when the collection set is empty).
2766 assert(result == NULL || result->in_collection_set(), "sanity");
2767 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2768 "should be updated only once per pause");
2769 _worker_cset_start_region[worker_i] = result;
2770 OrderAccess::storestore();
2771 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2772 return result;
2773 }
2774
2775 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2776 HeapRegion* r = g1_policy()->collection_set();
2777 while (r != NULL) {
2778 HeapRegion* next = r->next_in_collection_set();
2779 if (cl->doHeapRegion(r)) {
2780 cl->incomplete();
2781 return;
2782 }
2783 r = next;
2784 }
2785 }
2786
2787 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2788 HeapRegionClosure *cl) {
2789 if (r == NULL) {
2790 // The CSet is empty so there's nothing to do.
2791 return;
2792 }
2793
2794 assert(r->in_collection_set(),
2795 "Start region must be a member of the collection set.");
2796 HeapRegion* cur = r;
2797 while (cur != NULL) {
2798 HeapRegion* next = cur->next_in_collection_set();
2799 if (cl->doHeapRegion(cur) && false) {
2800 cl->incomplete();
2801 return;
2802 }
2803 cur = next;
2804 }
2805 cur = g1_policy()->collection_set();
2806 while (cur != r) {
2807 HeapRegion* next = cur->next_in_collection_set();
2808 if (cl->doHeapRegion(cur) && false) {
2809 cl->incomplete();
2810 return;
2811 }
2812 cur = next;
2813 }
2814 }
2815
2816 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2817 HeapRegion* result = _hrm.next_region_in_heap(from);
2818 while (result != NULL && result->is_pinned()) {
2819 result = _hrm.next_region_in_heap(result);
2820 }
2821 return result;
2822 }
2823
2824 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2825 HeapRegion* hr = heap_region_containing(addr);
2826 return hr->block_start(addr);
2827 }
2828
2829 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2830 HeapRegion* hr = heap_region_containing(addr);
2831 return hr->block_size(addr);
2832 }
2833
2834 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2835 HeapRegion* hr = heap_region_containing(addr);
2836 return hr->block_is_obj(addr);
2837 }
2838
2839 bool G1CollectedHeap::supports_tlab_allocation() const {
2840 return true;
2841 }
2842
2843 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2844 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2845 }
2846
2847 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2848 return young_list()->eden_used_bytes();
2849 }
2850
2851 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2852 // must be smaller than the humongous object limit.
2853 size_t G1CollectedHeap::max_tlab_size() const {
2854 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2855 }
2856
2857 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2858 AllocationContext_t context = AllocationContext::current();
2859 return _allocator->unsafe_max_tlab_alloc(context);
2860 }
2861
2862 size_t G1CollectedHeap::max_capacity() const {
2863 return _hrm.reserved().byte_size();
2864 }
2865
2866 jlong G1CollectedHeap::millis_since_last_gc() {
2867 // assert(false, "NYI");
2868 return 0;
2869 }
2870
2871 void G1CollectedHeap::prepare_for_verify() {
2872 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2873 ensure_parsability(false);
2874 }
2875 g1_rem_set()->prepare_for_verify();
2876 }
2877
2878 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2879 VerifyOption vo) {
2880 switch (vo) {
2881 case VerifyOption_G1UsePrevMarking:
2882 return hr->obj_allocated_since_prev_marking(obj);
2883 case VerifyOption_G1UseNextMarking:
2884 return hr->obj_allocated_since_next_marking(obj);
2885 case VerifyOption_G1UseMarkWord:
2886 return false;
2887 default:
2888 ShouldNotReachHere();
2889 }
2890 return false; // keep some compilers happy
2891 }
2892
2893 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2894 switch (vo) {
2895 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2896 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2897 case VerifyOption_G1UseMarkWord: return NULL;
2898 default: ShouldNotReachHere();
2899 }
2900 return NULL; // keep some compilers happy
2901 }
2902
2903 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2904 switch (vo) {
2905 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2906 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2907 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2908 default: ShouldNotReachHere();
2909 }
2910 return false; // keep some compilers happy
2911 }
2912
2913 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2914 switch (vo) {
2915 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2916 case VerifyOption_G1UseNextMarking: return "NTAMS";
2917 case VerifyOption_G1UseMarkWord: return "NONE";
2918 default: ShouldNotReachHere();
2919 }
2920 return NULL; // keep some compilers happy
2921 }
2922
2923 class VerifyRootsClosure: public OopClosure {
2924 private:
2925 G1CollectedHeap* _g1h;
2926 VerifyOption _vo;
2927 bool _failures;
2928 public:
2929 // _vo == UsePrevMarking -> use "prev" marking information,
2930 // _vo == UseNextMarking -> use "next" marking information,
2931 // _vo == UseMarkWord -> use mark word from object header.
2932 VerifyRootsClosure(VerifyOption vo) :
2933 _g1h(G1CollectedHeap::heap()),
2934 _vo(vo),
2935 _failures(false) { }
2936
2937 bool failures() { return _failures; }
2938
2939 template <class T> void do_oop_nv(T* p) {
2940 T heap_oop = oopDesc::load_heap_oop(p);
2941 if (!oopDesc::is_null(heap_oop)) {
2942 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2943 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2944 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2945 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2946 if (_vo == VerifyOption_G1UseMarkWord) {
2947 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2948 }
2949 obj->print_on(gclog_or_tty);
2950 _failures = true;
2951 }
2952 }
2953 }
2954
2955 void do_oop(oop* p) { do_oop_nv(p); }
2956 void do_oop(narrowOop* p) { do_oop_nv(p); }
2957 };
2958
2959 class G1VerifyCodeRootOopClosure: public OopClosure {
2960 G1CollectedHeap* _g1h;
2961 OopClosure* _root_cl;
2962 nmethod* _nm;
2963 VerifyOption _vo;
2964 bool _failures;
2965
2966 template <class T> void do_oop_work(T* p) {
2967 // First verify that this root is live
2968 _root_cl->do_oop(p);
2969
2970 if (!G1VerifyHeapRegionCodeRoots) {
2971 // We're not verifying the code roots attached to heap region.
2972 return;
2973 }
2974
2975 // Don't check the code roots during marking verification in a full GC
2976 if (_vo == VerifyOption_G1UseMarkWord) {
2977 return;
2978 }
2979
2980 // Now verify that the current nmethod (which contains p) is
2981 // in the code root list of the heap region containing the
2982 // object referenced by p.
2983
2984 T heap_oop = oopDesc::load_heap_oop(p);
2985 if (!oopDesc::is_null(heap_oop)) {
2986 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2987
2988 // Now fetch the region containing the object
2989 HeapRegion* hr = _g1h->heap_region_containing(obj);
2990 HeapRegionRemSet* hrrs = hr->rem_set();
2991 // Verify that the strong code root list for this region
2992 // contains the nmethod
2993 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2994 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2995 "from nmethod " PTR_FORMAT " not in strong "
2996 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2997 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2998 _failures = true;
2999 }
3000 }
3001 }
3002
3003 public:
3004 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3005 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3006
3007 void do_oop(oop* p) { do_oop_work(p); }
3008 void do_oop(narrowOop* p) { do_oop_work(p); }
3009
3010 void set_nmethod(nmethod* nm) { _nm = nm; }
3011 bool failures() { return _failures; }
3012 };
3013
3014 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3015 G1VerifyCodeRootOopClosure* _oop_cl;
3016
3017 public:
3018 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3019 _oop_cl(oop_cl) {}
3020
3021 void do_code_blob(CodeBlob* cb) {
3022 nmethod* nm = cb->as_nmethod_or_null();
3023 if (nm != NULL) {
3024 _oop_cl->set_nmethod(nm);
3025 nm->oops_do(_oop_cl);
3026 }
3027 }
3028 };
3029
3030 class YoungRefCounterClosure : public OopClosure {
3031 G1CollectedHeap* _g1h;
3032 int _count;
3033 public:
3034 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3035 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3036 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3037
3038 int count() { return _count; }
3039 void reset_count() { _count = 0; };
3040 };
3041
3042 class VerifyKlassClosure: public KlassClosure {
3043 YoungRefCounterClosure _young_ref_counter_closure;
3044 OopClosure *_oop_closure;
3045 public:
3046 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3047 void do_klass(Klass* k) {
3048 k->oops_do(_oop_closure);
3049
3050 _young_ref_counter_closure.reset_count();
3051 k->oops_do(&_young_ref_counter_closure);
3052 if (_young_ref_counter_closure.count() > 0) {
3053 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3054 }
3055 }
3056 };
3057
3058 class VerifyLivenessOopClosure: public OopClosure {
3059 G1CollectedHeap* _g1h;
3060 VerifyOption _vo;
3061 public:
3062 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3063 _g1h(g1h), _vo(vo)
3064 { }
3065 void do_oop(narrowOop *p) { do_oop_work(p); }
3066 void do_oop( oop *p) { do_oop_work(p); }
3067
3068 template <class T> void do_oop_work(T *p) {
3069 oop obj = oopDesc::load_decode_heap_oop(p);
3070 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3071 "Dead object referenced by a not dead object");
3072 }
3073 };
3074
3075 class VerifyObjsInRegionClosure: public ObjectClosure {
3076 private:
3077 G1CollectedHeap* _g1h;
3078 size_t _live_bytes;
3079 HeapRegion *_hr;
3080 VerifyOption _vo;
3081 public:
3082 // _vo == UsePrevMarking -> use "prev" marking information,
3083 // _vo == UseNextMarking -> use "next" marking information,
3084 // _vo == UseMarkWord -> use mark word from object header.
3085 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3086 : _live_bytes(0), _hr(hr), _vo(vo) {
3087 _g1h = G1CollectedHeap::heap();
3088 }
3089 void do_object(oop o) {
3090 VerifyLivenessOopClosure isLive(_g1h, _vo);
3091 assert(o != NULL, "Huh?");
3092 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3093 // If the object is alive according to the mark word,
3094 // then verify that the marking information agrees.
3095 // Note we can't verify the contra-positive of the
3096 // above: if the object is dead (according to the mark
3097 // word), it may not be marked, or may have been marked
3098 // but has since became dead, or may have been allocated
3099 // since the last marking.
3100 if (_vo == VerifyOption_G1UseMarkWord) {
3101 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3102 }
3103
3104 o->oop_iterate_no_header(&isLive);
3105 if (!_hr->obj_allocated_since_prev_marking(o)) {
3106 size_t obj_size = o->size(); // Make sure we don't overflow
3107 _live_bytes += (obj_size * HeapWordSize);
3108 }
3109 }
3110 }
3111 size_t live_bytes() { return _live_bytes; }
3112 };
3113
3114 class VerifyArchiveOopClosure: public OopClosure {
3115 public:
3116 VerifyArchiveOopClosure(HeapRegion *hr) { }
3117 void do_oop(narrowOop *p) { do_oop_work(p); }
3118 void do_oop( oop *p) { do_oop_work(p); }
3119
3120 template <class T> void do_oop_work(T *p) {
3121 oop obj = oopDesc::load_decode_heap_oop(p);
3122 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3123 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3124 p2i(p), p2i(obj)));
3125 }
3126 };
3127
3128 class VerifyArchiveRegionClosure: public ObjectClosure {
3129 public:
3130 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3131 // Verify that all object pointers are to archive regions.
3132 void do_object(oop o) {
3133 VerifyArchiveOopClosure checkOop(NULL);
3134 assert(o != NULL, "Should not be here for NULL oops");
3135 o->oop_iterate_no_header(&checkOop);
3136 }
3137 };
3138
3139 class VerifyRegionClosure: public HeapRegionClosure {
3140 private:
3141 bool _par;
3142 VerifyOption _vo;
3143 bool _failures;
3144 public:
3145 // _vo == UsePrevMarking -> use "prev" marking information,
3146 // _vo == UseNextMarking -> use "next" marking information,
3147 // _vo == UseMarkWord -> use mark word from object header.
3148 VerifyRegionClosure(bool par, VerifyOption vo)
3149 : _par(par),
3150 _vo(vo),
3151 _failures(false) {}
3152
3153 bool failures() {
3154 return _failures;
3155 }
3156
3157 bool doHeapRegion(HeapRegion* r) {
3158 // For archive regions, verify there are no heap pointers to
3159 // non-pinned regions. For all others, verify liveness info.
3160 if (r->is_archive()) {
3161 VerifyArchiveRegionClosure verify_oop_pointers(r);
3162 r->object_iterate(&verify_oop_pointers);
3163 return true;
3164 }
3165 if (!r->is_continues_humongous()) {
3166 bool failures = false;
3167 r->verify(_vo, &failures);
3168 if (failures) {
3169 _failures = true;
3170 } else {
3171 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3172 r->object_iterate(¬_dead_yet_cl);
3173 if (_vo != VerifyOption_G1UseNextMarking) {
3174 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3175 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3176 "max_live_bytes " SIZE_FORMAT " "
3177 "< calculated " SIZE_FORMAT,
3178 p2i(r->bottom()), p2i(r->end()),
3179 r->max_live_bytes(),
3180 not_dead_yet_cl.live_bytes());
3181 _failures = true;
3182 }
3183 } else {
3184 // When vo == UseNextMarking we cannot currently do a sanity
3185 // check on the live bytes as the calculation has not been
3186 // finalized yet.
3187 }
3188 }
3189 }
3190 return false; // stop the region iteration if we hit a failure
3191 }
3192 };
3193
3194 // This is the task used for parallel verification of the heap regions
3195
3196 class G1ParVerifyTask: public AbstractGangTask {
3197 private:
3198 G1CollectedHeap* _g1h;
3199 VerifyOption _vo;
3200 bool _failures;
3201 HeapRegionClaimer _hrclaimer;
3202
3203 public:
3204 // _vo == UsePrevMarking -> use "prev" marking information,
3205 // _vo == UseNextMarking -> use "next" marking information,
3206 // _vo == UseMarkWord -> use mark word from object header.
3207 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3208 AbstractGangTask("Parallel verify task"),
3209 _g1h(g1h),
3210 _vo(vo),
3211 _failures(false),
3212 _hrclaimer(g1h->workers()->active_workers()) {}
3213
3214 bool failures() {
3215 return _failures;
3216 }
3217
3218 void work(uint worker_id) {
3219 HandleMark hm;
3220 VerifyRegionClosure blk(true, _vo);
3221 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3222 if (blk.failures()) {
3223 _failures = true;
3224 }
3225 }
3226 };
3227
3228 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3229 if (SafepointSynchronize::is_at_safepoint()) {
3230 assert(Thread::current()->is_VM_thread(),
3231 "Expected to be executed serially by the VM thread at this point");
3232
3233 if (!silent) { gclog_or_tty->print("Roots "); }
3234 VerifyRootsClosure rootsCl(vo);
3235 VerifyKlassClosure klassCl(this, &rootsCl);
3236 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3237
3238 // We apply the relevant closures to all the oops in the
3239 // system dictionary, class loader data graph, the string table
3240 // and the nmethods in the code cache.
3241 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3242 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3243
3244 {
3245 G1RootProcessor root_processor(this, 1);
3246 root_processor.process_all_roots(&rootsCl,
3247 &cldCl,
3248 &blobsCl);
3249 }
3250
3251 bool failures = rootsCl.failures() || codeRootsCl.failures();
3252
3253 if (vo != VerifyOption_G1UseMarkWord) {
3254 // If we're verifying during a full GC then the region sets
3255 // will have been torn down at the start of the GC. Therefore
3256 // verifying the region sets will fail. So we only verify
3257 // the region sets when not in a full GC.
3258 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3259 verify_region_sets();
3260 }
3261
3262 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3263 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3264
3265 G1ParVerifyTask task(this, vo);
3266 workers()->run_task(&task);
3267 if (task.failures()) {
3268 failures = true;
3269 }
3270
3271 } else {
3272 VerifyRegionClosure blk(false, vo);
3273 heap_region_iterate(&blk);
3274 if (blk.failures()) {
3275 failures = true;
3276 }
3277 }
3278
3279 if (G1StringDedup::is_enabled()) {
3280 if (!silent) gclog_or_tty->print("StrDedup ");
3281 G1StringDedup::verify();
3282 }
3283
3284 if (failures) {
3285 gclog_or_tty->print_cr("Heap:");
3286 // It helps to have the per-region information in the output to
3287 // help us track down what went wrong. This is why we call
3288 // print_extended_on() instead of print_on().
3289 print_extended_on(gclog_or_tty);
3290 gclog_or_tty->cr();
3291 gclog_or_tty->flush();
3292 }
3293 guarantee(!failures, "there should not have been any failures");
3294 } else {
3295 if (!silent) {
3296 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3297 if (G1StringDedup::is_enabled()) {
3298 gclog_or_tty->print(", StrDedup");
3299 }
3300 gclog_or_tty->print(") ");
3301 }
3302 }
3303 }
3304
3305 void G1CollectedHeap::verify(bool silent) {
3306 verify(silent, VerifyOption_G1UsePrevMarking);
3307 }
3308
3309 double G1CollectedHeap::verify(bool guard, const char* msg) {
3310 double verify_time_ms = 0.0;
3311
3312 if (guard && total_collections() >= VerifyGCStartAt) {
3313 double verify_start = os::elapsedTime();
3314 HandleMark hm; // Discard invalid handles created during verification
3315 prepare_for_verify();
3316 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3317 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3318 }
3319
3320 return verify_time_ms;
3321 }
3322
3323 void G1CollectedHeap::verify_before_gc() {
3324 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3325 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3326 }
3327
3328 void G1CollectedHeap::verify_after_gc() {
3329 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3330 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3331 }
3332
3333 class PrintRegionClosure: public HeapRegionClosure {
3334 outputStream* _st;
3335 public:
3336 PrintRegionClosure(outputStream* st) : _st(st) {}
3337 bool doHeapRegion(HeapRegion* r) {
3338 r->print_on(_st);
3339 return false;
3340 }
3341 };
3342
3343 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3344 const HeapRegion* hr,
3345 const VerifyOption vo) const {
3346 switch (vo) {
3347 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3348 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3349 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3350 default: ShouldNotReachHere();
3351 }
3352 return false; // keep some compilers happy
3353 }
3354
3355 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3356 const VerifyOption vo) const {
3357 switch (vo) {
3358 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3359 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3360 case VerifyOption_G1UseMarkWord: {
3361 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3362 return !obj->is_gc_marked() && !hr->is_archive();
3363 }
3364 default: ShouldNotReachHere();
3365 }
3366 return false; // keep some compilers happy
3367 }
3368
3369 void G1CollectedHeap::print_on(outputStream* st) const {
3370 st->print(" %-20s", "garbage-first heap");
3371 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3372 capacity()/K, used_unlocked()/K);
3373 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3374 p2i(_hrm.reserved().start()),
3375 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3376 p2i(_hrm.reserved().end()));
3377 st->cr();
3378 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3379 uint young_regions = _young_list->length();
3380 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3381 (size_t) young_regions * HeapRegion::GrainBytes / K);
3382 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3383 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3384 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3385 st->cr();
3386 MetaspaceAux::print_on(st);
3387 }
3388
3389 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3390 print_on(st);
3391
3392 // Print the per-region information.
3393 st->cr();
3394 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3395 "HS=humongous(starts), HC=humongous(continues), "
3396 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3397 "PTAMS=previous top-at-mark-start, "
3398 "NTAMS=next top-at-mark-start)");
3399 PrintRegionClosure blk(st);
3400 heap_region_iterate(&blk);
3401 }
3402
3403 void G1CollectedHeap::print_on_error(outputStream* st) const {
3404 this->CollectedHeap::print_on_error(st);
3405
3406 if (_cm != NULL) {
3407 st->cr();
3408 _cm->print_on_error(st);
3409 }
3410 }
3411
3412 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3413 workers()->print_worker_threads_on(st);
3414 _cmThread->print_on(st);
3415 st->cr();
3416 _cm->print_worker_threads_on(st);
3417 _cg1r->print_worker_threads_on(st);
3418 if (G1StringDedup::is_enabled()) {
3419 G1StringDedup::print_worker_threads_on(st);
3420 }
3421 }
3422
3423 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3424 workers()->threads_do(tc);
3425 tc->do_thread(_cmThread);
3426 _cg1r->threads_do(tc);
3427 if (G1StringDedup::is_enabled()) {
3428 G1StringDedup::threads_do(tc);
3429 }
3430 }
3431
3432 void G1CollectedHeap::print_tracing_info() const {
3433 // We'll overload this to mean "trace GC pause statistics."
3434 if (TraceYoungGenTime || TraceOldGenTime) {
3435 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3436 // to that.
3437 g1_policy()->print_tracing_info();
3438 }
3439 if (G1SummarizeRSetStats) {
3440 g1_rem_set()->print_summary_info();
3441 }
3442 if (G1SummarizeConcMark) {
3443 concurrent_mark()->print_summary_info();
3444 }
3445 g1_policy()->print_yg_surv_rate_info();
3446 }
3447
3448 #ifndef PRODUCT
3449 // Helpful for debugging RSet issues.
3450
3451 class PrintRSetsClosure : public HeapRegionClosure {
3452 private:
3453 const char* _msg;
3454 size_t _occupied_sum;
3455
3456 public:
3457 bool doHeapRegion(HeapRegion* r) {
3458 HeapRegionRemSet* hrrs = r->rem_set();
3459 size_t occupied = hrrs->occupied();
3460 _occupied_sum += occupied;
3461
3462 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3463 HR_FORMAT_PARAMS(r));
3464 if (occupied == 0) {
3465 gclog_or_tty->print_cr(" RSet is empty");
3466 } else {
3467 hrrs->print();
3468 }
3469 gclog_or_tty->print_cr("----------");
3470 return false;
3471 }
3472
3473 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3474 gclog_or_tty->cr();
3475 gclog_or_tty->print_cr("========================================");
3476 gclog_or_tty->print_cr("%s", msg);
3477 gclog_or_tty->cr();
3478 }
3479
3480 ~PrintRSetsClosure() {
3481 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3482 gclog_or_tty->print_cr("========================================");
3483 gclog_or_tty->cr();
3484 }
3485 };
3486
3487 void G1CollectedHeap::print_cset_rsets() {
3488 PrintRSetsClosure cl("Printing CSet RSets");
3489 collection_set_iterate(&cl);
3490 }
3491
3492 void G1CollectedHeap::print_all_rsets() {
3493 PrintRSetsClosure cl("Printing All RSets");;
3494 heap_region_iterate(&cl);
3495 }
3496 #endif // PRODUCT
3497
3498 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3499 YoungList* young_list = heap()->young_list();
3500
3501 size_t eden_used_bytes = young_list->eden_used_bytes();
3502 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3503
3504 size_t eden_capacity_bytes =
3505 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3506
3507 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3508 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3509 }
3510
3511 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3512 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3513 stats->unused(), stats->used(), stats->region_end_waste(),
3514 stats->regions_filled(), stats->direct_allocated(),
3515 stats->failure_used(), stats->failure_waste());
3516 }
3517
3518 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3519 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3520 gc_tracer->report_gc_heap_summary(when, heap_summary);
3521
3522 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3523 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3524 }
3525
3526
3527 G1CollectedHeap* G1CollectedHeap::heap() {
3528 CollectedHeap* heap = Universe::heap();
3529 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3530 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3531 return (G1CollectedHeap*)heap;
3532 }
3533
3534 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3535 // always_do_update_barrier = false;
3536 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3537 // Fill TLAB's and such
3538 accumulate_statistics_all_tlabs();
3539 ensure_parsability(true);
3540
3541 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3542 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3543 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3544 }
3545 }
3546
3547 void G1CollectedHeap::gc_epilogue(bool full) {
3548
3549 if (G1SummarizeRSetStats &&
3550 (G1SummarizeRSetStatsPeriod > 0) &&
3551 // we are at the end of the GC. Total collections has already been increased.
3552 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3553 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3554 }
3555
3556 // FIXME: what is this about?
3557 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3558 // is set.
3559 #if defined(COMPILER2) || INCLUDE_JVMCI
3560 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3561 #endif
3562 // always_do_update_barrier = true;
3563
3564 resize_all_tlabs();
3565 allocation_context_stats().update(full);
3566
3567 // We have just completed a GC. Update the soft reference
3568 // policy with the new heap occupancy
3569 Universe::update_heap_info_at_gc();
3570 }
3571
3572 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3573 uint gc_count_before,
3574 bool* succeeded,
3575 GCCause::Cause gc_cause) {
3576 assert_heap_not_locked_and_not_at_safepoint();
3577 g1_policy()->record_stop_world_start();
3578 VM_G1IncCollectionPause op(gc_count_before,
3579 word_size,
3580 false, /* should_initiate_conc_mark */
3581 g1_policy()->max_pause_time_ms(),
3582 gc_cause);
3583
3584 op.set_allocation_context(AllocationContext::current());
3585 VMThread::execute(&op);
3586
3587 HeapWord* result = op.result();
3588 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3589 assert(result == NULL || ret_succeeded,
3590 "the result should be NULL if the VM did not succeed");
3591 *succeeded = ret_succeeded;
3592
3593 assert_heap_not_locked();
3594 return result;
3595 }
3596
3597 void
3598 G1CollectedHeap::doConcurrentMark() {
3599 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3600 if (!_cmThread->in_progress()) {
3601 _cmThread->set_started();
3602 CGC_lock->notify();
3603 }
3604 }
3605
3606 size_t G1CollectedHeap::pending_card_num() {
3607 size_t extra_cards = 0;
3608 JavaThread *curr = Threads::first();
3609 while (curr != NULL) {
3610 DirtyCardQueue& dcq = curr->dirty_card_queue();
3611 extra_cards += dcq.size();
3612 curr = curr->next();
3613 }
3614 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3615 size_t buffer_size = dcqs.buffer_size();
3616 size_t buffer_num = dcqs.completed_buffers_num();
3617
3618 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3619 // in bytes - not the number of 'entries'. We need to convert
3620 // into a number of cards.
3621 return (buffer_size * buffer_num + extra_cards) / oopSize;
3622 }
3623
3624 size_t G1CollectedHeap::cards_scanned() {
3625 return g1_rem_set()->cardsScanned();
3626 }
3627
3628 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3629 private:
3630 size_t _total_humongous;
3631 size_t _candidate_humongous;
3632
3633 DirtyCardQueue _dcq;
3634
3635 // We don't nominate objects with many remembered set entries, on
3636 // the assumption that such objects are likely still live.
3637 bool is_remset_small(HeapRegion* region) const {
3638 HeapRegionRemSet* const rset = region->rem_set();
3639 return G1EagerReclaimHumongousObjectsWithStaleRefs
3640 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3641 : rset->is_empty();
3642 }
3643
3644 bool is_typeArray_region(HeapRegion* region) const {
3645 return oop(region->bottom())->is_typeArray();
3646 }
3647
3648 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3649 assert(region->is_starts_humongous(), "Must start a humongous object");
3650
3651 // Candidate selection must satisfy the following constraints
3652 // while concurrent marking is in progress:
3653 //
3654 // * In order to maintain SATB invariants, an object must not be
3655 // reclaimed if it was allocated before the start of marking and
3656 // has not had its references scanned. Such an object must have
3657 // its references (including type metadata) scanned to ensure no
3658 // live objects are missed by the marking process. Objects
3659 // allocated after the start of concurrent marking don't need to
3660 // be scanned.
3661 //
3662 // * An object must not be reclaimed if it is on the concurrent
3663 // mark stack. Objects allocated after the start of concurrent
3664 // marking are never pushed on the mark stack.
3665 //
3666 // Nominating only objects allocated after the start of concurrent
3667 // marking is sufficient to meet both constraints. This may miss
3668 // some objects that satisfy the constraints, but the marking data
3669 // structures don't support efficiently performing the needed
3670 // additional tests or scrubbing of the mark stack.
3671 //
3672 // However, we presently only nominate is_typeArray() objects.
3673 // A humongous object containing references induces remembered
3674 // set entries on other regions. In order to reclaim such an
3675 // object, those remembered sets would need to be cleaned up.
3676 //
3677 // We also treat is_typeArray() objects specially, allowing them
3678 // to be reclaimed even if allocated before the start of
3679 // concurrent mark. For this we rely on mark stack insertion to
3680 // exclude is_typeArray() objects, preventing reclaiming an object
3681 // that is in the mark stack. We also rely on the metadata for
3682 // such objects to be built-in and so ensured to be kept live.
3683 // Frequent allocation and drop of large binary blobs is an
3684 // important use case for eager reclaim, and this special handling
3685 // may reduce needed headroom.
3686
3687 return is_typeArray_region(region) && is_remset_small(region);
3688 }
3689
3690 public:
3691 RegisterHumongousWithInCSetFastTestClosure()
3692 : _total_humongous(0),
3693 _candidate_humongous(0),
3694 _dcq(&JavaThread::dirty_card_queue_set()) {
3695 }
3696
3697 virtual bool doHeapRegion(HeapRegion* r) {
3698 if (!r->is_starts_humongous()) {
3699 return false;
3700 }
3701 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3702
3703 bool is_candidate = humongous_region_is_candidate(g1h, r);
3704 uint rindex = r->hrm_index();
3705 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3706 if (is_candidate) {
3707 _candidate_humongous++;
3708 g1h->register_humongous_region_with_cset(rindex);
3709 // Is_candidate already filters out humongous object with large remembered sets.
3710 // If we have a humongous object with a few remembered sets, we simply flush these
3711 // remembered set entries into the DCQS. That will result in automatic
3712 // re-evaluation of their remembered set entries during the following evacuation
3713 // phase.
3714 if (!r->rem_set()->is_empty()) {
3715 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3716 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3717 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3718 HeapRegionRemSetIterator hrrs(r->rem_set());
3719 size_t card_index;
3720 while (hrrs.has_next(card_index)) {
3721 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3722 // The remembered set might contain references to already freed
3723 // regions. Filter out such entries to avoid failing card table
3724 // verification.
3725 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3726 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3727 *card_ptr = CardTableModRefBS::dirty_card_val();
3728 _dcq.enqueue(card_ptr);
3729 }
3730 }
3731 }
3732 r->rem_set()->clear_locked();
3733 }
3734 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3735 }
3736 _total_humongous++;
3737
3738 return false;
3739 }
3740
3741 size_t total_humongous() const { return _total_humongous; }
3742 size_t candidate_humongous() const { return _candidate_humongous; }
3743
3744 void flush_rem_set_entries() { _dcq.flush(); }
3745 };
3746
3747 void G1CollectedHeap::register_humongous_regions_with_cset() {
3748 if (!G1EagerReclaimHumongousObjects) {
3749 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3750 return;
3751 }
3752 double time = os::elapsed_counter();
3753
3754 // Collect reclaim candidate information and register candidates with cset.
3755 RegisterHumongousWithInCSetFastTestClosure cl;
3756 heap_region_iterate(&cl);
3757
3758 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3759 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3760 cl.total_humongous(),
3761 cl.candidate_humongous());
3762 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3763
3764 // Finally flush all remembered set entries to re-check into the global DCQS.
3765 cl.flush_rem_set_entries();
3766 }
3767
3768 void G1CollectedHeap::setup_surviving_young_words() {
3769 assert(_surviving_young_words == NULL, "pre-condition");
3770 uint array_length = g1_policy()->young_cset_region_length();
3771 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3772 if (_surviving_young_words == NULL) {
3773 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3774 "Not enough space for young surv words summary.");
3775 }
3776 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3777 #ifdef ASSERT
3778 for (uint i = 0; i < array_length; ++i) {
3779 assert( _surviving_young_words[i] == 0, "memset above" );
3780 }
3781 #endif // !ASSERT
3782 }
3783
3784 void G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3785 assert_at_safepoint(true);
3786 uint array_length = g1_policy()->young_cset_region_length();
3787 for (uint i = 0; i < array_length; ++i) {
3788 _surviving_young_words[i] += surv_young_words[i];
3789 }
3790 }
3791
3792 void G1CollectedHeap::cleanup_surviving_young_words() {
3793 guarantee( _surviving_young_words != NULL, "pre-condition" );
3794 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3795 _surviving_young_words = NULL;
3796 }
3797
3798 #ifdef ASSERT
3799 class VerifyCSetClosure: public HeapRegionClosure {
3800 public:
3801 bool doHeapRegion(HeapRegion* hr) {
3802 // Here we check that the CSet region's RSet is ready for parallel
3803 // iteration. The fields that we'll verify are only manipulated
3804 // when the region is part of a CSet and is collected. Afterwards,
3805 // we reset these fields when we clear the region's RSet (when the
3806 // region is freed) so they are ready when the region is
3807 // re-allocated. The only exception to this is if there's an
3808 // evacuation failure and instead of freeing the region we leave
3809 // it in the heap. In that case, we reset these fields during
3810 // evacuation failure handling.
3811 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3812
3813 // Here's a good place to add any other checks we'd like to
3814 // perform on CSet regions.
3815 return false;
3816 }
3817 };
3818 #endif // ASSERT
3819
3820 uint G1CollectedHeap::num_task_queues() const {
3821 return _task_queues->size();
3822 }
3823
3824 #if TASKQUEUE_STATS
3825 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3826 st->print_raw_cr("GC Task Stats");
3827 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3828 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3829 }
3830
3831 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3832 print_taskqueue_stats_hdr(st);
3833
3834 TaskQueueStats totals;
3835 const uint n = num_task_queues();
3836 for (uint i = 0; i < n; ++i) {
3837 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3838 totals += task_queue(i)->stats;
3839 }
3840 st->print_raw("tot "); totals.print(st); st->cr();
3841
3842 DEBUG_ONLY(totals.verify());
3843 }
3844
3845 void G1CollectedHeap::reset_taskqueue_stats() {
3846 const uint n = num_task_queues();
3847 for (uint i = 0; i < n; ++i) {
3848 task_queue(i)->stats.reset();
3849 }
3850 }
3851 #endif // TASKQUEUE_STATS
3852
3853 void G1CollectedHeap::log_gc_header() {
3854 if (!G1Log::fine()) {
3855 return;
3856 }
3857
3858 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3859
3860 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3861 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3862 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3863
3864 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3865 }
3866
3867 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3868 if (!G1Log::fine()) {
3869 return;
3870 }
3871
3872 if (G1Log::finer()) {
3873 if (evacuation_failed()) {
3874 gclog_or_tty->print(" (to-space exhausted)");
3875 }
3876 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3877 g1_policy()->phase_times()->note_gc_end();
3878 g1_policy()->phase_times()->print(pause_time_sec);
3879 g1_policy()->print_detailed_heap_transition();
3880 } else {
3881 if (evacuation_failed()) {
3882 gclog_or_tty->print("--");
3883 }
3884 g1_policy()->print_heap_transition();
3885 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3886 }
3887 gclog_or_tty->flush();
3888 }
3889
3890 void G1CollectedHeap::wait_for_root_region_scanning() {
3891 double scan_wait_start = os::elapsedTime();
3892 // We have to wait until the CM threads finish scanning the
3893 // root regions as it's the only way to ensure that all the
3894 // objects on them have been correctly scanned before we start
3895 // moving them during the GC.
3896 bool waited = _cm->root_regions()->wait_until_scan_finished();
3897 double wait_time_ms = 0.0;
3898 if (waited) {
3899 double scan_wait_end = os::elapsedTime();
3900 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3901 }
3902 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3903 }
3904
3905 bool
3906 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3907 assert_at_safepoint(true /* should_be_vm_thread */);
3908 guarantee(!is_gc_active(), "collection is not reentrant");
3909
3910 if (GC_locker::check_active_before_gc()) {
3911 return false;
3912 }
3913
3914 _gc_timer_stw->register_gc_start();
3915
3916 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3917
3918 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3919 ResourceMark rm;
3920
3921 wait_for_root_region_scanning();
3922
3923 G1Log::update_level();
3924 print_heap_before_gc();
3925 trace_heap_before_gc(_gc_tracer_stw);
3926
3927 verify_region_sets_optional();
3928 verify_dirty_young_regions();
3929
3930 // This call will decide whether this pause is an initial-mark
3931 // pause. If it is, during_initial_mark_pause() will return true
3932 // for the duration of this pause.
3933 g1_policy()->decide_on_conc_mark_initiation();
3934
3935 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3936 assert(!collector_state()->during_initial_mark_pause() ||
3937 collector_state()->gcs_are_young(), "sanity");
3938
3939 // We also do not allow mixed GCs during marking.
3940 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3941
3942 // Record whether this pause is an initial mark. When the current
3943 // thread has completed its logging output and it's safe to signal
3944 // the CM thread, the flag's value in the policy has been reset.
3945 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3946
3947 // Inner scope for scope based logging, timers, and stats collection
3948 {
3949 EvacuationInfo evacuation_info;
3950
3951 if (collector_state()->during_initial_mark_pause()) {
3952 // We are about to start a marking cycle, so we increment the
3953 // full collection counter.
3954 increment_old_marking_cycles_started();
3955 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3956 }
3957
3958 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3959
3960 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3961
3962 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3963 workers()->active_workers(),
3964 Threads::number_of_non_daemon_threads());
3965 workers()->set_active_workers(active_workers);
3966
3967 double pause_start_sec = os::elapsedTime();
3968 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
3969 log_gc_header();
3970
3971 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3972 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3973
3974 // If the secondary_free_list is not empty, append it to the
3975 // free_list. No need to wait for the cleanup operation to finish;
3976 // the region allocation code will check the secondary_free_list
3977 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3978 // set, skip this step so that the region allocation code has to
3979 // get entries from the secondary_free_list.
3980 if (!G1StressConcRegionFreeing) {
3981 append_secondary_free_list_if_not_empty_with_lock();
3982 }
3983
3984 assert(check_young_list_well_formed(), "young list should be well formed");
3985
3986 // Don't dynamically change the number of GC threads this early. A value of
3987 // 0 is used to indicate serial work. When parallel work is done,
3988 // it will be set.
3989
3990 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3991 IsGCActiveMark x;
3992
3993 gc_prologue(false);
3994 increment_total_collections(false /* full gc */);
3995 increment_gc_time_stamp();
3996
3997 verify_before_gc();
3998
3999 check_bitmaps("GC Start");
4000
4001 #if defined(COMPILER2) || INCLUDE_JVMCI
4002 DerivedPointerTable::clear();
4003 #endif
4004
4005 // Please see comment in g1CollectedHeap.hpp and
4006 // G1CollectedHeap::ref_processing_init() to see how
4007 // reference processing currently works in G1.
4008
4009 // Enable discovery in the STW reference processor
4010 ref_processor_stw()->enable_discovery();
4011
4012 {
4013 // We want to temporarily turn off discovery by the
4014 // CM ref processor, if necessary, and turn it back on
4015 // on again later if we do. Using a scoped
4016 // NoRefDiscovery object will do this.
4017 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4018
4019 // Forget the current alloc region (we might even choose it to be part
4020 // of the collection set!).
4021 _allocator->release_mutator_alloc_region();
4022
4023 // We should call this after we retire the mutator alloc
4024 // region(s) so that all the ALLOC / RETIRE events are generated
4025 // before the start GC event.
4026 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4027
4028 // This timing is only used by the ergonomics to handle our pause target.
4029 // It is unclear why this should not include the full pause. We will
4030 // investigate this in CR 7178365.
4031 //
4032 // Preserving the old comment here if that helps the investigation:
4033 //
4034 // The elapsed time induced by the start time below deliberately elides
4035 // the possible verification above.
4036 double sample_start_time_sec = os::elapsedTime();
4037
4038 #if YOUNG_LIST_VERBOSE
4039 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4040 _young_list->print();
4041 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4042 #endif // YOUNG_LIST_VERBOSE
4043
4044 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4045
4046 #if YOUNG_LIST_VERBOSE
4047 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4048 _young_list->print();
4049 #endif // YOUNG_LIST_VERBOSE
4050
4051 if (collector_state()->during_initial_mark_pause()) {
4052 concurrent_mark()->checkpointRootsInitialPre();
4053 }
4054
4055 #if YOUNG_LIST_VERBOSE
4056 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4057 _young_list->print();
4058 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4059 #endif // YOUNG_LIST_VERBOSE
4060
4061 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4062
4063 register_humongous_regions_with_cset();
4064
4065 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4066
4067 _cm->note_start_of_gc();
4068 // We call this after finalize_cset() to
4069 // ensure that the CSet has been finalized.
4070 _cm->verify_no_cset_oops();
4071
4072 if (_hr_printer.is_active()) {
4073 HeapRegion* hr = g1_policy()->collection_set();
4074 while (hr != NULL) {
4075 _hr_printer.cset(hr);
4076 hr = hr->next_in_collection_set();
4077 }
4078 }
4079
4080 #ifdef ASSERT
4081 VerifyCSetClosure cl;
4082 collection_set_iterate(&cl);
4083 #endif // ASSERT
4084
4085 setup_surviving_young_words();
4086
4087 // Initialize the GC alloc regions.
4088 _allocator->init_gc_alloc_regions(evacuation_info);
4089
4090 // Actually do the work...
4091 evacuate_collection_set(evacuation_info);
4092
4093 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4094
4095 eagerly_reclaim_humongous_regions();
4096
4097 g1_policy()->clear_collection_set();
4098
4099 cleanup_surviving_young_words();
4100
4101 // Start a new incremental collection set for the next pause.
4102 g1_policy()->start_incremental_cset_building();
4103
4104 clear_cset_fast_test();
4105
4106 _young_list->reset_sampled_info();
4107
4108 // Don't check the whole heap at this point as the
4109 // GC alloc regions from this pause have been tagged
4110 // as survivors and moved on to the survivor list.
4111 // Survivor regions will fail the !is_young() check.
4112 assert(check_young_list_empty(false /* check_heap */),
4113 "young list should be empty");
4114
4115 #if YOUNG_LIST_VERBOSE
4116 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4117 _young_list->print();
4118 #endif // YOUNG_LIST_VERBOSE
4119
4120 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4121 _young_list->first_survivor_region(),
4122 _young_list->last_survivor_region());
4123
4124 _young_list->reset_auxilary_lists();
4125
4126 if (evacuation_failed()) {
4127 set_used(recalculate_used());
4128 if (_archive_allocator != NULL) {
4129 _archive_allocator->clear_used();
4130 }
4131 for (uint i = 0; i < ParallelGCThreads; i++) {
4132 if (_evacuation_failed_info_array[i].has_failed()) {
4133 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4134 }
4135 }
4136 } else {
4137 // The "used" of the the collection set have already been subtracted
4138 // when they were freed. Add in the bytes evacuated.
4139 increase_used(g1_policy()->bytes_copied_during_gc());
4140 }
4141
4142 if (collector_state()->during_initial_mark_pause()) {
4143 // We have to do this before we notify the CM threads that
4144 // they can start working to make sure that all the
4145 // appropriate initialization is done on the CM object.
4146 concurrent_mark()->checkpointRootsInitialPost();
4147 collector_state()->set_mark_in_progress(true);
4148 // Note that we don't actually trigger the CM thread at
4149 // this point. We do that later when we're sure that
4150 // the current thread has completed its logging output.
4151 }
4152
4153 allocate_dummy_regions();
4154
4155 #if YOUNG_LIST_VERBOSE
4156 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4157 _young_list->print();
4158 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4159 #endif // YOUNG_LIST_VERBOSE
4160
4161 _allocator->init_mutator_alloc_region();
4162
4163 {
4164 size_t expand_bytes = g1_policy()->expansion_amount();
4165 if (expand_bytes > 0) {
4166 size_t bytes_before = capacity();
4167 // No need for an ergo verbose message here,
4168 // expansion_amount() does this when it returns a value > 0.
4169 if (!expand(expand_bytes)) {
4170 // We failed to expand the heap. Cannot do anything about it.
4171 }
4172 }
4173 }
4174
4175 // We redo the verification but now wrt to the new CSet which
4176 // has just got initialized after the previous CSet was freed.
4177 _cm->verify_no_cset_oops();
4178 _cm->note_end_of_gc();
4179
4180 // This timing is only used by the ergonomics to handle our pause target.
4181 // It is unclear why this should not include the full pause. We will
4182 // investigate this in CR 7178365.
4183 double sample_end_time_sec = os::elapsedTime();
4184 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4185 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4186
4187 MemoryService::track_memory_usage();
4188
4189 // In prepare_for_verify() below we'll need to scan the deferred
4190 // update buffers to bring the RSets up-to-date if
4191 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4192 // the update buffers we'll probably need to scan cards on the
4193 // regions we just allocated to (i.e., the GC alloc
4194 // regions). However, during the last GC we called
4195 // set_saved_mark() on all the GC alloc regions, so card
4196 // scanning might skip the [saved_mark_word()...top()] area of
4197 // those regions (i.e., the area we allocated objects into
4198 // during the last GC). But it shouldn't. Given that
4199 // saved_mark_word() is conditional on whether the GC time stamp
4200 // on the region is current or not, by incrementing the GC time
4201 // stamp here we invalidate all the GC time stamps on all the
4202 // regions and saved_mark_word() will simply return top() for
4203 // all the regions. This is a nicer way of ensuring this rather
4204 // than iterating over the regions and fixing them. In fact, the
4205 // GC time stamp increment here also ensures that
4206 // saved_mark_word() will return top() between pauses, i.e.,
4207 // during concurrent refinement. So we don't need the
4208 // is_gc_active() check to decided which top to use when
4209 // scanning cards (see CR 7039627).
4210 increment_gc_time_stamp();
4211
4212 verify_after_gc();
4213 check_bitmaps("GC End");
4214
4215 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4216 ref_processor_stw()->verify_no_references_recorded();
4217
4218 // CM reference discovery will be re-enabled if necessary.
4219 }
4220
4221 // We should do this after we potentially expand the heap so
4222 // that all the COMMIT events are generated before the end GC
4223 // event, and after we retire the GC alloc regions so that all
4224 // RETIRE events are generated before the end GC event.
4225 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4226
4227 #ifdef TRACESPINNING
4228 ParallelTaskTerminator::print_termination_counts();
4229 #endif
4230
4231 gc_epilogue(false);
4232 }
4233
4234 // Print the remainder of the GC log output.
4235 log_gc_footer(os::elapsedTime() - pause_start_sec);
4236
4237 // It is not yet to safe to tell the concurrent mark to
4238 // start as we have some optional output below. We don't want the
4239 // output from the concurrent mark thread interfering with this
4240 // logging output either.
4241
4242 _hrm.verify_optional();
4243 verify_region_sets_optional();
4244
4245 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4246 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4247
4248 print_heap_after_gc();
4249 trace_heap_after_gc(_gc_tracer_stw);
4250
4251 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4252 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4253 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4254 // before any GC notifications are raised.
4255 g1mm()->update_sizes();
4256
4257 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4258 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4259 _gc_timer_stw->register_gc_end();
4260 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4261 }
4262 // It should now be safe to tell the concurrent mark thread to start
4263 // without its logging output interfering with the logging output
4264 // that came from the pause.
4265
4266 if (should_start_conc_mark) {
4267 // CAUTION: after the doConcurrentMark() call below,
4268 // the concurrent marking thread(s) could be running
4269 // concurrently with us. Make sure that anything after
4270 // this point does not assume that we are the only GC thread
4271 // running. Note: of course, the actual marking work will
4272 // not start until the safepoint itself is released in
4273 // SuspendibleThreadSet::desynchronize().
4274 doConcurrentMark();
4275 }
4276
4277 return true;
4278 }
4279
4280 void G1CollectedHeap::remove_self_forwarding_pointers() {
4281 double remove_self_forwards_start = os::elapsedTime();
4282
4283 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4284 workers()->run_task(&rsfp_task);
4285
4286 // Now restore saved marks, if any.
4287 for (uint i = 0; i < ParallelGCThreads; i++) {
4288 OopAndMarkOopStack& cur = _preserved_objs[i];
4289 while (!cur.is_empty()) {
4290 OopAndMarkOop elem = cur.pop();
4291 elem.set_mark();
4292 }
4293 cur.clear(true);
4294 }
4295
4296 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4297 }
4298
4299 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4300 if (!_evacuation_failed) {
4301 _evacuation_failed = true;
4302 }
4303
4304 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4305
4306 // We want to call the "for_promotion_failure" version only in the
4307 // case of a promotion failure.
4308 if (m->must_be_preserved_for_promotion_failure(obj)) {
4309 OopAndMarkOop elem(obj, m);
4310 _preserved_objs[worker_id].push(elem);
4311 }
4312 }
4313
4314 void G1ParCopyHelper::mark_object(oop obj) {
4315 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4316
4317 // We know that the object is not moving so it's safe to read its size.
4318 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4319 }
4320
4321 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4322 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4323 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4324 assert(from_obj != to_obj, "should not be self-forwarded");
4325
4326 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4327 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4328
4329 // The object might be in the process of being copied by another
4330 // worker so we cannot trust that its to-space image is
4331 // well-formed. So we have to read its size from its from-space
4332 // image which we know should not be changing.
4333 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4334 }
4335
4336 template <class T>
4337 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4338 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4339 _scanned_klass->record_modified_oops();
4340 }
4341 }
4342
4343 template <G1Barrier barrier, G1Mark do_mark_object>
4344 template <class T>
4345 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4346 T heap_oop = oopDesc::load_heap_oop(p);
4347
4348 if (oopDesc::is_null(heap_oop)) {
4349 return;
4350 }
4351
4352 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4353
4354 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4355
4356 const InCSetState state = _g1->in_cset_state(obj);
4357 if (state.is_in_cset()) {
4358 oop forwardee;
4359 markOop m = obj->mark();
4360 if (m->is_marked()) {
4361 forwardee = (oop) m->decode_pointer();
4362 } else {
4363 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4364 }
4365 assert(forwardee != NULL, "forwardee should not be NULL");
4366 oopDesc::encode_store_heap_oop(p, forwardee);
4367 if (do_mark_object != G1MarkNone && forwardee != obj) {
4368 // If the object is self-forwarded we don't need to explicitly
4369 // mark it, the evacuation failure protocol will do so.
4370 mark_forwarded_object(obj, forwardee);
4371 }
4372
4373 if (barrier == G1BarrierKlass) {
4374 do_klass_barrier(p, forwardee);
4375 }
4376 } else {
4377 if (state.is_humongous()) {
4378 _g1->set_humongous_is_live(obj);
4379 }
4380 // The object is not in collection set. If we're a root scanning
4381 // closure during an initial mark pause then attempt to mark the object.
4382 if (do_mark_object == G1MarkFromRoot) {
4383 mark_object(obj);
4384 }
4385 }
4386 }
4387
4388 class G1ParEvacuateFollowersClosure : public VoidClosure {
4389 private:
4390 double _start_term;
4391 double _term_time;
4392 size_t _term_attempts;
4393
4394 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4395 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4396 protected:
4397 G1CollectedHeap* _g1h;
4398 G1ParScanThreadState* _par_scan_state;
4399 RefToScanQueueSet* _queues;
4400 ParallelTaskTerminator* _terminator;
4401
4402 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4403 RefToScanQueueSet* queues() { return _queues; }
4404 ParallelTaskTerminator* terminator() { return _terminator; }
4405
4406 public:
4407 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4408 G1ParScanThreadState* par_scan_state,
4409 RefToScanQueueSet* queues,
4410 ParallelTaskTerminator* terminator)
4411 : _g1h(g1h), _par_scan_state(par_scan_state),
4412 _queues(queues), _terminator(terminator),
4413 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4414
4415 void do_void();
4416
4417 double term_time() const { return _term_time; }
4418 size_t term_attempts() const { return _term_attempts; }
4419
4420 private:
4421 inline bool offer_termination();
4422 };
4423
4424 bool G1ParEvacuateFollowersClosure::offer_termination() {
4425 G1ParScanThreadState* const pss = par_scan_state();
4426 start_term_time();
4427 const bool res = terminator()->offer_termination();
4428 end_term_time();
4429 return res;
4430 }
4431
4432 void G1ParEvacuateFollowersClosure::do_void() {
4433 G1ParScanThreadState* const pss = par_scan_state();
4434 pss->trim_queue();
4435 do {
4436 pss->steal_and_trim_queue(queues());
4437 } while (!offer_termination());
4438 }
4439
4440 class G1KlassScanClosure : public KlassClosure {
4441 G1ParCopyHelper* _closure;
4442 bool _process_only_dirty;
4443 int _count;
4444 public:
4445 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4446 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4447 void do_klass(Klass* klass) {
4448 // If the klass has not been dirtied we know that there's
4449 // no references into the young gen and we can skip it.
4450 if (!_process_only_dirty || klass->has_modified_oops()) {
4451 // Clean the klass since we're going to scavenge all the metadata.
4452 klass->clear_modified_oops();
4453
4454 // Tell the closure that this klass is the Klass to scavenge
4455 // and is the one to dirty if oops are left pointing into the young gen.
4456 _closure->set_scanned_klass(klass);
4457
4458 klass->oops_do(_closure);
4459
4460 _closure->set_scanned_klass(NULL);
4461 }
4462 _count++;
4463 }
4464 };
4465
4466 class G1ParTask : public AbstractGangTask {
4467 protected:
4468 G1CollectedHeap* _g1h;
4469 G1ParScanThreadState** _pss;
4470 RefToScanQueueSet* _queues;
4471 G1RootProcessor* _root_processor;
4472 ParallelTaskTerminator _terminator;
4473 uint _n_workers;
4474
4475 public:
4476 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadState** per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4477 : AbstractGangTask("G1 collection"),
4478 _g1h(g1h),
4479 _pss(per_thread_states),
4480 _queues(task_queues),
4481 _root_processor(root_processor),
4482 _terminator(n_workers, _queues),
4483 _n_workers(n_workers)
4484 {}
4485
4486 RefToScanQueueSet* queues() { return _queues; }
4487
4488 RefToScanQueue *work_queue(int i) {
4489 return queues()->queue(i);
4490 }
4491
4492 ParallelTaskTerminator* terminator() { return &_terminator; }
4493
4494 // Helps out with CLD processing.
4495 //
4496 // During InitialMark we need to:
4497 // 1) Scavenge all CLDs for the young GC.
4498 // 2) Mark all objects directly reachable from strong CLDs.
4499 template <G1Mark do_mark_object>
4500 class G1CLDClosure : public CLDClosure {
4501 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4502 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4503 G1KlassScanClosure _klass_in_cld_closure;
4504 bool _claim;
4505
4506 public:
4507 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4508 bool only_young, bool claim)
4509 : _oop_closure(oop_closure),
4510 _oop_in_klass_closure(oop_closure->g1(),
4511 oop_closure->pss(),
4512 oop_closure->rp()),
4513 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4514 _claim(claim) {
4515
4516 }
4517
4518 void do_cld(ClassLoaderData* cld) {
4519 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4520 }
4521 };
4522
4523 void work(uint worker_id) {
4524 if (worker_id >= _n_workers) return; // no work needed this round
4525
4526 double start_sec = os::elapsedTime();
4527 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4528
4529 {
4530 ResourceMark rm;
4531 HandleMark hm;
4532
4533 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4534
4535 G1ParScanThreadState* pss = _pss[worker_id];
4536 pss->set_ref_processor(rp);
4537
4538 bool only_young = _g1h->collector_state()->gcs_are_young();
4539
4540 // Non-IM young GC.
4541 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss, rp);
4542 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4543 only_young, // Only process dirty klasses.
4544 false); // No need to claim CLDs.
4545 // IM young GC.
4546 // Strong roots closures.
4547 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss, rp);
4548 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4549 false, // Process all klasses.
4550 true); // Need to claim CLDs.
4551 // Weak roots closures.
4552 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss, rp);
4553 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4554 false, // Process all klasses.
4555 true); // Need to claim CLDs.
4556
4557 OopClosure* strong_root_cl;
4558 OopClosure* weak_root_cl;
4559 CLDClosure* strong_cld_cl;
4560 CLDClosure* weak_cld_cl;
4561
4562 bool trace_metadata = false;
4563
4564 if (_g1h->collector_state()->during_initial_mark_pause()) {
4565 // We also need to mark copied objects.
4566 strong_root_cl = &scan_mark_root_cl;
4567 strong_cld_cl = &scan_mark_cld_cl;
4568 if (ClassUnloadingWithConcurrentMark) {
4569 weak_root_cl = &scan_mark_weak_root_cl;
4570 weak_cld_cl = &scan_mark_weak_cld_cl;
4571 trace_metadata = true;
4572 } else {
4573 weak_root_cl = &scan_mark_root_cl;
4574 weak_cld_cl = &scan_mark_cld_cl;
4575 }
4576 } else {
4577 strong_root_cl = &scan_only_root_cl;
4578 weak_root_cl = &scan_only_root_cl;
4579 strong_cld_cl = &scan_only_cld_cl;
4580 weak_cld_cl = &scan_only_cld_cl;
4581 }
4582
4583 double start_strong_roots_sec = os::elapsedTime();
4584 _root_processor->evacuate_roots(strong_root_cl,
4585 weak_root_cl,
4586 strong_cld_cl,
4587 weak_cld_cl,
4588 trace_metadata,
4589 worker_id);
4590
4591 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4592 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4593 weak_root_cl,
4594 worker_id);
4595 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4596
4597 double term_sec = 0.0;
4598 size_t evac_term_attempts = 0;
4599 {
4600 double start = os::elapsedTime();
4601 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4602 evac.do_void();
4603
4604 evac_term_attempts = evac.term_attempts();
4605 term_sec = evac.term_time();
4606 double elapsed_sec = os::elapsedTime() - start;
4607 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4608 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4609 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4610 }
4611
4612 assert(pss->queue_is_empty(), "should be empty");
4613
4614 if (PrintTerminationStats) {
4615 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4616 size_t lab_waste;
4617 size_t lab_undo_waste;
4618 pss->waste(lab_waste, lab_undo_waste);
4619 _g1h->print_termination_stats(gclog_or_tty,
4620 worker_id,
4621 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4622 strong_roots_sec * 1000.0, /* strong roots time */
4623 term_sec * 1000.0, /* evac term time */
4624 evac_term_attempts, /* evac term attempts */
4625 lab_waste, /* alloc buffer waste */
4626 lab_undo_waste /* undo waste */
4627 );
4628 }
4629
4630 // Close the inner scope so that the ResourceMark and HandleMark
4631 // destructors are executed here and are included as part of the
4632 // "GC Worker Time".
4633 }
4634 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4635 }
4636 };
4637
4638 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4639 st->print_raw_cr("GC Termination Stats");
4640 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4641 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4642 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4643 }
4644
4645 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4646 uint worker_id,
4647 double elapsed_ms,
4648 double strong_roots_ms,
4649 double term_ms,
4650 size_t term_attempts,
4651 size_t alloc_buffer_waste,
4652 size_t undo_waste) const {
4653 st->print_cr("%3d %9.2f %9.2f %6.2f "
4654 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4655 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4656 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4657 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4658 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4659 alloc_buffer_waste * HeapWordSize / K,
4660 undo_waste * HeapWordSize / K);
4661 }
4662
4663 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4664 private:
4665 BoolObjectClosure* _is_alive;
4666 int _initial_string_table_size;
4667 int _initial_symbol_table_size;
4668
4669 bool _process_strings;
4670 int _strings_processed;
4671 int _strings_removed;
4672
4673 bool _process_symbols;
4674 int _symbols_processed;
4675 int _symbols_removed;
4676
4677 public:
4678 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4679 AbstractGangTask("String/Symbol Unlinking"),
4680 _is_alive(is_alive),
4681 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4682 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4683
4684 _initial_string_table_size = StringTable::the_table()->table_size();
4685 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4686 if (process_strings) {
4687 StringTable::clear_parallel_claimed_index();
4688 }
4689 if (process_symbols) {
4690 SymbolTable::clear_parallel_claimed_index();
4691 }
4692 }
4693
4694 ~G1StringSymbolTableUnlinkTask() {
4695 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4696 err_msg("claim value %d after unlink less than initial string table size %d",
4697 StringTable::parallel_claimed_index(), _initial_string_table_size));
4698 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4699 err_msg("claim value %d after unlink less than initial symbol table size %d",
4700 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4701
4702 if (G1TraceStringSymbolTableScrubbing) {
4703 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4704 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4705 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4706 strings_processed(), strings_removed(),
4707 symbols_processed(), symbols_removed());
4708 }
4709 }
4710
4711 void work(uint worker_id) {
4712 int strings_processed = 0;
4713 int strings_removed = 0;
4714 int symbols_processed = 0;
4715 int symbols_removed = 0;
4716 if (_process_strings) {
4717 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4718 Atomic::add(strings_processed, &_strings_processed);
4719 Atomic::add(strings_removed, &_strings_removed);
4720 }
4721 if (_process_symbols) {
4722 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4723 Atomic::add(symbols_processed, &_symbols_processed);
4724 Atomic::add(symbols_removed, &_symbols_removed);
4725 }
4726 }
4727
4728 size_t strings_processed() const { return (size_t)_strings_processed; }
4729 size_t strings_removed() const { return (size_t)_strings_removed; }
4730
4731 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4732 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4733 };
4734
4735 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4736 private:
4737 static Monitor* _lock;
4738
4739 BoolObjectClosure* const _is_alive;
4740 const bool _unloading_occurred;
4741 const uint _num_workers;
4742
4743 // Variables used to claim nmethods.
4744 nmethod* _first_nmethod;
4745 volatile nmethod* _claimed_nmethod;
4746
4747 // The list of nmethods that need to be processed by the second pass.
4748 volatile nmethod* _postponed_list;
4749 volatile uint _num_entered_barrier;
4750
4751 public:
4752 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4753 _is_alive(is_alive),
4754 _unloading_occurred(unloading_occurred),
4755 _num_workers(num_workers),
4756 _first_nmethod(NULL),
4757 _claimed_nmethod(NULL),
4758 _postponed_list(NULL),
4759 _num_entered_barrier(0)
4760 {
4761 nmethod::increase_unloading_clock();
4762 // Get first alive nmethod
4763 NMethodIterator iter = NMethodIterator();
4764 if(iter.next_alive()) {
4765 _first_nmethod = iter.method();
4766 }
4767 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4768 }
4769
4770 ~G1CodeCacheUnloadingTask() {
4771 CodeCache::verify_clean_inline_caches();
4772
4773 CodeCache::set_needs_cache_clean(false);
4774 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4775
4776 CodeCache::verify_icholder_relocations();
4777 }
4778
4779 private:
4780 void add_to_postponed_list(nmethod* nm) {
4781 nmethod* old;
4782 do {
4783 old = (nmethod*)_postponed_list;
4784 nm->set_unloading_next(old);
4785 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4786 }
4787
4788 void clean_nmethod(nmethod* nm) {
4789 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4790
4791 if (postponed) {
4792 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4793 add_to_postponed_list(nm);
4794 }
4795
4796 // Mark that this thread has been cleaned/unloaded.
4797 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4798 nm->set_unloading_clock(nmethod::global_unloading_clock());
4799 }
4800
4801 void clean_nmethod_postponed(nmethod* nm) {
4802 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4803 }
4804
4805 static const int MaxClaimNmethods = 16;
4806
4807 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4808 nmethod* first;
4809 NMethodIterator last;
4810
4811 do {
4812 *num_claimed_nmethods = 0;
4813
4814 first = (nmethod*)_claimed_nmethod;
4815 last = NMethodIterator(first);
4816
4817 if (first != NULL) {
4818
4819 for (int i = 0; i < MaxClaimNmethods; i++) {
4820 if (!last.next_alive()) {
4821 break;
4822 }
4823 claimed_nmethods[i] = last.method();
4824 (*num_claimed_nmethods)++;
4825 }
4826 }
4827
4828 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4829 }
4830
4831 nmethod* claim_postponed_nmethod() {
4832 nmethod* claim;
4833 nmethod* next;
4834
4835 do {
4836 claim = (nmethod*)_postponed_list;
4837 if (claim == NULL) {
4838 return NULL;
4839 }
4840
4841 next = claim->unloading_next();
4842
4843 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4844
4845 return claim;
4846 }
4847
4848 public:
4849 // Mark that we're done with the first pass of nmethod cleaning.
4850 void barrier_mark(uint worker_id) {
4851 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4852 _num_entered_barrier++;
4853 if (_num_entered_barrier == _num_workers) {
4854 ml.notify_all();
4855 }
4856 }
4857
4858 // See if we have to wait for the other workers to
4859 // finish their first-pass nmethod cleaning work.
4860 void barrier_wait(uint worker_id) {
4861 if (_num_entered_barrier < _num_workers) {
4862 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4863 while (_num_entered_barrier < _num_workers) {
4864 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4865 }
4866 }
4867 }
4868
4869 // Cleaning and unloading of nmethods. Some work has to be postponed
4870 // to the second pass, when we know which nmethods survive.
4871 void work_first_pass(uint worker_id) {
4872 // The first nmethods is claimed by the first worker.
4873 if (worker_id == 0 && _first_nmethod != NULL) {
4874 clean_nmethod(_first_nmethod);
4875 _first_nmethod = NULL;
4876 }
4877
4878 int num_claimed_nmethods;
4879 nmethod* claimed_nmethods[MaxClaimNmethods];
4880
4881 while (true) {
4882 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4883
4884 if (num_claimed_nmethods == 0) {
4885 break;
4886 }
4887
4888 for (int i = 0; i < num_claimed_nmethods; i++) {
4889 clean_nmethod(claimed_nmethods[i]);
4890 }
4891 }
4892 }
4893
4894 void work_second_pass(uint worker_id) {
4895 nmethod* nm;
4896 // Take care of postponed nmethods.
4897 while ((nm = claim_postponed_nmethod()) != NULL) {
4898 clean_nmethod_postponed(nm);
4899 }
4900 }
4901 };
4902
4903 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4904
4905 class G1KlassCleaningTask : public StackObj {
4906 BoolObjectClosure* _is_alive;
4907 volatile jint _clean_klass_tree_claimed;
4908 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4909
4910 public:
4911 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4912 _is_alive(is_alive),
4913 _clean_klass_tree_claimed(0),
4914 _klass_iterator() {
4915 }
4916
4917 private:
4918 bool claim_clean_klass_tree_task() {
4919 if (_clean_klass_tree_claimed) {
4920 return false;
4921 }
4922
4923 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4924 }
4925
4926 InstanceKlass* claim_next_klass() {
4927 Klass* klass;
4928 do {
4929 klass =_klass_iterator.next_klass();
4930 } while (klass != NULL && !klass->oop_is_instance());
4931
4932 return (InstanceKlass*)klass;
4933 }
4934
4935 public:
4936
4937 void clean_klass(InstanceKlass* ik) {
4938 ik->clean_implementors_list(_is_alive);
4939 ik->clean_method_data(_is_alive);
4940
4941 // G1 specific cleanup work that has
4942 // been moved here to be done in parallel.
4943 ik->clean_dependent_nmethods();
4944 }
4945
4946 void work() {
4947 ResourceMark rm;
4948
4949 // One worker will clean the subklass/sibling klass tree.
4950 if (claim_clean_klass_tree_task()) {
4951 Klass::clean_subklass_tree(_is_alive);
4952 }
4953
4954 // All workers will help cleaning the classes,
4955 InstanceKlass* klass;
4956 while ((klass = claim_next_klass()) != NULL) {
4957 clean_klass(klass);
4958 }
4959 }
4960 };
4961
4962 // To minimize the remark pause times, the tasks below are done in parallel.
4963 class G1ParallelCleaningTask : public AbstractGangTask {
4964 private:
4965 G1StringSymbolTableUnlinkTask _string_symbol_task;
4966 G1CodeCacheUnloadingTask _code_cache_task;
4967 G1KlassCleaningTask _klass_cleaning_task;
4968
4969 public:
4970 // The constructor is run in the VMThread.
4971 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4972 AbstractGangTask("Parallel Cleaning"),
4973 _string_symbol_task(is_alive, process_strings, process_symbols),
4974 _code_cache_task(num_workers, is_alive, unloading_occurred),
4975 _klass_cleaning_task(is_alive) {
4976 }
4977
4978 // The parallel work done by all worker threads.
4979 void work(uint worker_id) {
4980 // Do first pass of code cache cleaning.
4981 _code_cache_task.work_first_pass(worker_id);
4982
4983 // Let the threads mark that the first pass is done.
4984 _code_cache_task.barrier_mark(worker_id);
4985
4986 // Clean the Strings and Symbols.
4987 _string_symbol_task.work(worker_id);
4988
4989 // Wait for all workers to finish the first code cache cleaning pass.
4990 _code_cache_task.barrier_wait(worker_id);
4991
4992 // Do the second code cache cleaning work, which realize on
4993 // the liveness information gathered during the first pass.
4994 _code_cache_task.work_second_pass(worker_id);
4995
4996 // Clean all klasses that were not unloaded.
4997 _klass_cleaning_task.work();
4998 }
4999 };
5000
5001
5002 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5003 bool process_strings,
5004 bool process_symbols,
5005 bool class_unloading_occurred) {
5006 uint n_workers = workers()->active_workers();
5007
5008 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5009 n_workers, class_unloading_occurred);
5010 workers()->run_task(&g1_unlink_task);
5011 }
5012
5013 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5014 bool process_strings, bool process_symbols) {
5015 {
5016 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5017 workers()->run_task(&g1_unlink_task);
5018 }
5019
5020 if (G1StringDedup::is_enabled()) {
5021 G1StringDedup::unlink(is_alive);
5022 }
5023 }
5024
5025 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5026 private:
5027 DirtyCardQueueSet* _queue;
5028 public:
5029 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5030
5031 virtual void work(uint worker_id) {
5032 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5033 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5034
5035 RedirtyLoggedCardTableEntryClosure cl;
5036 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5037
5038 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5039 }
5040 };
5041
5042 void G1CollectedHeap::redirty_logged_cards() {
5043 double redirty_logged_cards_start = os::elapsedTime();
5044
5045 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5046 dirty_card_queue_set().reset_for_par_iteration();
5047 workers()->run_task(&redirty_task);
5048
5049 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5050 dcq.merge_bufferlists(&dirty_card_queue_set());
5051 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5052
5053 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5054 }
5055
5056 // Weak Reference Processing support
5057
5058 // An always "is_alive" closure that is used to preserve referents.
5059 // If the object is non-null then it's alive. Used in the preservation
5060 // of referent objects that are pointed to by reference objects
5061 // discovered by the CM ref processor.
5062 class G1AlwaysAliveClosure: public BoolObjectClosure {
5063 G1CollectedHeap* _g1;
5064 public:
5065 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5066 bool do_object_b(oop p) {
5067 if (p != NULL) {
5068 return true;
5069 }
5070 return false;
5071 }
5072 };
5073
5074 bool G1STWIsAliveClosure::do_object_b(oop p) {
5075 // An object is reachable if it is outside the collection set,
5076 // or is inside and copied.
5077 return !_g1->is_in_cset(p) || p->is_forwarded();
5078 }
5079
5080 // Non Copying Keep Alive closure
5081 class G1KeepAliveClosure: public OopClosure {
5082 G1CollectedHeap* _g1;
5083 public:
5084 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5085 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5086 void do_oop(oop* p) {
5087 oop obj = *p;
5088 assert(obj != NULL, "the caller should have filtered out NULL values");
5089
5090 const InCSetState cset_state = _g1->in_cset_state(obj);
5091 if (!cset_state.is_in_cset_or_humongous()) {
5092 return;
5093 }
5094 if (cset_state.is_in_cset()) {
5095 assert( obj->is_forwarded(), "invariant" );
5096 *p = obj->forwardee();
5097 } else {
5098 assert(!obj->is_forwarded(), "invariant" );
5099 assert(cset_state.is_humongous(),
5100 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5101 _g1->set_humongous_is_live(obj);
5102 }
5103 }
5104 };
5105
5106 // Copying Keep Alive closure - can be called from both
5107 // serial and parallel code as long as different worker
5108 // threads utilize different G1ParScanThreadState instances
5109 // and different queues.
5110
5111 class G1CopyingKeepAliveClosure: public OopClosure {
5112 G1CollectedHeap* _g1h;
5113 OopClosure* _copy_non_heap_obj_cl;
5114 G1ParScanThreadState* _par_scan_state;
5115
5116 public:
5117 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5118 OopClosure* non_heap_obj_cl,
5119 G1ParScanThreadState* pss):
5120 _g1h(g1h),
5121 _copy_non_heap_obj_cl(non_heap_obj_cl),
5122 _par_scan_state(pss)
5123 {}
5124
5125 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5126 virtual void do_oop( oop* p) { do_oop_work(p); }
5127
5128 template <class T> void do_oop_work(T* p) {
5129 oop obj = oopDesc::load_decode_heap_oop(p);
5130
5131 if (_g1h->is_in_cset_or_humongous(obj)) {
5132 // If the referent object has been forwarded (either copied
5133 // to a new location or to itself in the event of an
5134 // evacuation failure) then we need to update the reference
5135 // field and, if both reference and referent are in the G1
5136 // heap, update the RSet for the referent.
5137 //
5138 // If the referent has not been forwarded then we have to keep
5139 // it alive by policy. Therefore we have copy the referent.
5140 //
5141 // If the reference field is in the G1 heap then we can push
5142 // on the PSS queue. When the queue is drained (after each
5143 // phase of reference processing) the object and it's followers
5144 // will be copied, the reference field set to point to the
5145 // new location, and the RSet updated. Otherwise we need to
5146 // use the the non-heap or metadata closures directly to copy
5147 // the referent object and update the pointer, while avoiding
5148 // updating the RSet.
5149
5150 if (_g1h->is_in_g1_reserved(p)) {
5151 _par_scan_state->push_on_queue(p);
5152 } else {
5153 assert(!Metaspace::contains((const void*)p),
5154 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5155 _copy_non_heap_obj_cl->do_oop(p);
5156 }
5157 }
5158 }
5159 };
5160
5161 // Serial drain queue closure. Called as the 'complete_gc'
5162 // closure for each discovered list in some of the
5163 // reference processing phases.
5164
5165 class G1STWDrainQueueClosure: public VoidClosure {
5166 protected:
5167 G1CollectedHeap* _g1h;
5168 G1ParScanThreadState* _par_scan_state;
5169
5170 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5171
5172 public:
5173 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5174 _g1h(g1h),
5175 _par_scan_state(pss)
5176 { }
5177
5178 void do_void() {
5179 G1ParScanThreadState* const pss = par_scan_state();
5180 pss->trim_queue();
5181 }
5182 };
5183
5184 // Parallel Reference Processing closures
5185
5186 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5187 // processing during G1 evacuation pauses.
5188
5189 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5190 private:
5191 G1CollectedHeap* _g1h;
5192 G1ParScanThreadState** _pss;
5193 RefToScanQueueSet* _queues;
5194 WorkGang* _workers;
5195 uint _active_workers;
5196
5197 public:
5198 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5199 G1ParScanThreadState** per_thread_states,
5200 WorkGang* workers,
5201 RefToScanQueueSet *task_queues,
5202 uint n_workers) :
5203 _g1h(g1h),
5204 _pss(per_thread_states),
5205 _queues(task_queues),
5206 _workers(workers),
5207 _active_workers(n_workers)
5208 {
5209 assert(n_workers > 0, "shouldn't call this otherwise");
5210 }
5211
5212 // Executes the given task using concurrent marking worker threads.
5213 virtual void execute(ProcessTask& task);
5214 virtual void execute(EnqueueTask& task);
5215 };
5216
5217 // Gang task for possibly parallel reference processing
5218
5219 class G1STWRefProcTaskProxy: public AbstractGangTask {
5220 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5221 ProcessTask& _proc_task;
5222 G1CollectedHeap* _g1h;
5223 G1ParScanThreadState** _pss;
5224 RefToScanQueueSet* _task_queues;
5225 ParallelTaskTerminator* _terminator;
5226
5227 public:
5228 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5229 G1CollectedHeap* g1h,
5230 G1ParScanThreadState** per_thread_states,
5231 RefToScanQueueSet *task_queues,
5232 ParallelTaskTerminator* terminator) :
5233 AbstractGangTask("Process reference objects in parallel"),
5234 _proc_task(proc_task),
5235 _g1h(g1h),
5236 _pss(per_thread_states),
5237 _task_queues(task_queues),
5238 _terminator(terminator)
5239 {}
5240
5241 virtual void work(uint worker_id) {
5242 // The reference processing task executed by a single worker.
5243 ResourceMark rm;
5244 HandleMark hm;
5245
5246 G1STWIsAliveClosure is_alive(_g1h);
5247
5248 G1ParScanThreadState* pss = _pss[worker_id];
5249 pss->set_ref_processor(NULL);
5250
5251 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss, NULL);
5252
5253 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss, NULL);
5254
5255 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5256
5257 if (_g1h->collector_state()->during_initial_mark_pause()) {
5258 // We also need to mark copied objects.
5259 copy_non_heap_cl = ©_mark_non_heap_cl;
5260 }
5261
5262 // Keep alive closure.
5263 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5264
5265 // Complete GC closure
5266 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5267
5268 // Call the reference processing task's work routine.
5269 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5270
5271 // Note we cannot assert that the refs array is empty here as not all
5272 // of the processing tasks (specifically phase2 - pp2_work) execute
5273 // the complete_gc closure (which ordinarily would drain the queue) so
5274 // the queue may not be empty.
5275 }
5276 };
5277
5278 // Driver routine for parallel reference processing.
5279 // Creates an instance of the ref processing gang
5280 // task and has the worker threads execute it.
5281 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5282 assert(_workers != NULL, "Need parallel worker threads.");
5283
5284 ParallelTaskTerminator terminator(_active_workers, _queues);
5285 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5286
5287 _workers->run_task(&proc_task_proxy);
5288 }
5289
5290 // Gang task for parallel reference enqueueing.
5291
5292 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5293 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5294 EnqueueTask& _enq_task;
5295
5296 public:
5297 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5298 AbstractGangTask("Enqueue reference objects in parallel"),
5299 _enq_task(enq_task)
5300 { }
5301
5302 virtual void work(uint worker_id) {
5303 _enq_task.work(worker_id);
5304 }
5305 };
5306
5307 // Driver routine for parallel reference enqueueing.
5308 // Creates an instance of the ref enqueueing gang
5309 // task and has the worker threads execute it.
5310
5311 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5312 assert(_workers != NULL, "Need parallel worker threads.");
5313
5314 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5315
5316 _workers->run_task(&enq_task_proxy);
5317 }
5318
5319 // End of weak reference support closures
5320
5321 // Abstract task used to preserve (i.e. copy) any referent objects
5322 // that are in the collection set and are pointed to by reference
5323 // objects discovered by the CM ref processor.
5324
5325 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5326 protected:
5327 G1CollectedHeap* _g1h;
5328 G1ParScanThreadState** _pss;
5329 RefToScanQueueSet* _queues;
5330 ParallelTaskTerminator _terminator;
5331 uint _n_workers;
5332
5333 public:
5334 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadState** per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5335 AbstractGangTask("ParPreserveCMReferents"),
5336 _g1h(g1h),
5337 _pss(per_thread_states),
5338 _queues(task_queues),
5339 _terminator(workers, _queues),
5340 _n_workers(workers)
5341 { }
5342
5343 void work(uint worker_id) {
5344 ResourceMark rm;
5345 HandleMark hm;
5346
5347 G1ParScanThreadState* pss = _pss[worker_id];
5348 pss->set_ref_processor(NULL);
5349 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5350
5351 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss, NULL);
5352
5353 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss, NULL);
5354
5355 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5356
5357 if (_g1h->collector_state()->during_initial_mark_pause()) {
5358 // We also need to mark copied objects.
5359 copy_non_heap_cl = ©_mark_non_heap_cl;
5360 }
5361
5362 // Is alive closure
5363 G1AlwaysAliveClosure always_alive(_g1h);
5364
5365 // Copying keep alive closure. Applied to referent objects that need
5366 // to be copied.
5367 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5368
5369 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5370
5371 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5372 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5373
5374 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5375 // So this must be true - but assert just in case someone decides to
5376 // change the worker ids.
5377 assert(worker_id < limit, "sanity");
5378 assert(!rp->discovery_is_atomic(), "check this code");
5379
5380 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5381 for (uint idx = worker_id; idx < limit; idx += stride) {
5382 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5383
5384 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5385 while (iter.has_next()) {
5386 // Since discovery is not atomic for the CM ref processor, we
5387 // can see some null referent objects.
5388 iter.load_ptrs(DEBUG_ONLY(true));
5389 oop ref = iter.obj();
5390
5391 // This will filter nulls.
5392 if (iter.is_referent_alive()) {
5393 iter.make_referent_alive();
5394 }
5395 iter.move_to_next();
5396 }
5397 }
5398
5399 // Drain the queue - which may cause stealing
5400 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5401 drain_queue.do_void();
5402 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5403 assert(pss->queue_is_empty(), "should be");
5404 }
5405 };
5406
5407 // Weak Reference processing during an evacuation pause (part 1).
5408 void G1CollectedHeap::process_discovered_references(G1ParScanThreadState** per_thread_states) {
5409 double ref_proc_start = os::elapsedTime();
5410
5411 ReferenceProcessor* rp = _ref_processor_stw;
5412 assert(rp->discovery_enabled(), "should have been enabled");
5413
5414 // Any reference objects, in the collection set, that were 'discovered'
5415 // by the CM ref processor should have already been copied (either by
5416 // applying the external root copy closure to the discovered lists, or
5417 // by following an RSet entry).
5418 //
5419 // But some of the referents, that are in the collection set, that these
5420 // reference objects point to may not have been copied: the STW ref
5421 // processor would have seen that the reference object had already
5422 // been 'discovered' and would have skipped discovering the reference,
5423 // but would not have treated the reference object as a regular oop.
5424 // As a result the copy closure would not have been applied to the
5425 // referent object.
5426 //
5427 // We need to explicitly copy these referent objects - the references
5428 // will be processed at the end of remarking.
5429 //
5430 // We also need to do this copying before we process the reference
5431 // objects discovered by the STW ref processor in case one of these
5432 // referents points to another object which is also referenced by an
5433 // object discovered by the STW ref processor.
5434
5435 uint no_of_gc_workers = workers()->active_workers();
5436
5437 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5438 per_thread_states,
5439 no_of_gc_workers,
5440 _task_queues);
5441
5442 workers()->run_task(&keep_cm_referents);
5443
5444 // Closure to test whether a referent is alive.
5445 G1STWIsAliveClosure is_alive(this);
5446
5447 // Even when parallel reference processing is enabled, the processing
5448 // of JNI refs is serial and performed serially by the current thread
5449 // rather than by a worker. The following PSS will be used for processing
5450 // JNI refs.
5451
5452 // Use only a single queue for this PSS.
5453 G1ParScanThreadState* pss = per_thread_states[0];
5454 pss->set_ref_processor(NULL);
5455 assert(pss->queue_is_empty(), "pre-condition");
5456
5457 // We do not embed a reference processor in the copying/scanning
5458 // closures while we're actually processing the discovered
5459 // reference objects.
5460
5461 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss, NULL);
5462
5463 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss, NULL);
5464
5465 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5466
5467 if (collector_state()->during_initial_mark_pause()) {
5468 // We also need to mark copied objects.
5469 copy_non_heap_cl = ©_mark_non_heap_cl;
5470 }
5471
5472 // Keep alive closure.
5473 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5474
5475 // Serial Complete GC closure
5476 G1STWDrainQueueClosure drain_queue(this, pss);
5477
5478 // Setup the soft refs policy...
5479 rp->setup_policy(false);
5480
5481 ReferenceProcessorStats stats;
5482 if (!rp->processing_is_mt()) {
5483 // Serial reference processing...
5484 stats = rp->process_discovered_references(&is_alive,
5485 &keep_alive,
5486 &drain_queue,
5487 NULL,
5488 _gc_timer_stw,
5489 _gc_tracer_stw->gc_id());
5490 } else {
5491 // Parallel reference processing
5492 assert(rp->num_q() == no_of_gc_workers, "sanity");
5493 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5494
5495 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5496 stats = rp->process_discovered_references(&is_alive,
5497 &keep_alive,
5498 &drain_queue,
5499 &par_task_executor,
5500 _gc_timer_stw,
5501 _gc_tracer_stw->gc_id());
5502 }
5503
5504 _gc_tracer_stw->report_gc_reference_stats(stats);
5505
5506 // We have completed copying any necessary live referent objects.
5507 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5508
5509 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5510 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5511 }
5512
5513 // Weak Reference processing during an evacuation pause (part 2).
5514 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadState** per_thread_states) {
5515 double ref_enq_start = os::elapsedTime();
5516
5517 ReferenceProcessor* rp = _ref_processor_stw;
5518 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5519
5520 // Now enqueue any remaining on the discovered lists on to
5521 // the pending list.
5522 if (!rp->processing_is_mt()) {
5523 // Serial reference processing...
5524 rp->enqueue_discovered_references();
5525 } else {
5526 // Parallel reference enqueueing
5527
5528 uint n_workers = workers()->active_workers();
5529
5530 assert(rp->num_q() == n_workers, "sanity");
5531 assert(n_workers <= rp->max_num_q(), "sanity");
5532
5533 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5534 rp->enqueue_discovered_references(&par_task_executor);
5535 }
5536
5537 rp->verify_no_references_recorded();
5538 assert(!rp->discovery_enabled(), "should have been disabled");
5539
5540 // FIXME
5541 // CM's reference processing also cleans up the string and symbol tables.
5542 // Should we do that here also? We could, but it is a serial operation
5543 // and could significantly increase the pause time.
5544
5545 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5546 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5547 }
5548
5549 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5550 _expand_heap_after_alloc_failure = true;
5551 _evacuation_failed = false;
5552
5553 // Should G1EvacuationFailureALot be in effect for this GC?
5554 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5555
5556 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5557
5558 // Disable the hot card cache.
5559 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5560 hot_card_cache->reset_hot_cache_claimed_index();
5561 hot_card_cache->set_use_cache(false);
5562
5563 const uint n_workers = workers()->active_workers();
5564
5565 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5566 double start_par_time_sec = os::elapsedTime();
5567 double end_par_time_sec;
5568
5569 G1ParScanThreadState** per_thread_states = NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC);
5570 for (uint i = 0; i < n_workers; i++) {
5571 per_thread_states[i] = new_par_scan_state(i);
5572 }
5573
5574 {
5575 G1RootProcessor root_processor(this, n_workers);
5576 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5577 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5578 if (collector_state()->during_initial_mark_pause()) {
5579 ClassLoaderDataGraph::clear_claimed_marks();
5580 }
5581
5582 // The individual threads will set their evac-failure closures.
5583 if (PrintTerminationStats) {
5584 print_termination_stats_hdr(gclog_or_tty);
5585 }
5586
5587 workers()->run_task(&g1_par_task);
5588 end_par_time_sec = os::elapsedTime();
5589
5590 // Closing the inner scope will execute the destructor
5591 // for the G1RootProcessor object. We record the current
5592 // elapsed time before closing the scope so that time
5593 // taken for the destructor is NOT included in the
5594 // reported parallel time.
5595 }
5596
5597 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5598
5599 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5600 phase_times->record_par_time(par_time_ms);
5601
5602 double code_root_fixup_time_ms =
5603 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5604 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5605
5606 // Process any discovered reference objects - we have
5607 // to do this _before_ we retire the GC alloc regions
5608 // as we may have to copy some 'reachable' referent
5609 // objects (and their reachable sub-graphs) that were
5610 // not copied during the pause.
5611 process_discovered_references(per_thread_states);
5612
5613 if (G1StringDedup::is_enabled()) {
5614 double fixup_start = os::elapsedTime();
5615
5616 G1STWIsAliveClosure is_alive(this);
5617 G1KeepAliveClosure keep_alive(this);
5618 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5619
5620 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5621 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5622 }
5623
5624 _allocator->release_gc_alloc_regions(evacuation_info);
5625 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5626
5627 for (uint i = 0; i < n_workers; i++) {
5628 G1ParScanThreadState* pss = per_thread_states[i];
5629 delete pss;
5630 }
5631 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, per_thread_states);
5632
5633 record_obj_copy_mem_stats();
5634
5635 // Reset and re-enable the hot card cache.
5636 // Note the counts for the cards in the regions in the
5637 // collection set are reset when the collection set is freed.
5638 hot_card_cache->reset_hot_cache();
5639 hot_card_cache->set_use_cache(true);
5640
5641 purge_code_root_memory();
5642
5643 if (evacuation_failed()) {
5644 remove_self_forwarding_pointers();
5645
5646 // Reset the G1EvacuationFailureALot counters and flags
5647 // Note: the values are reset only when an actual
5648 // evacuation failure occurs.
5649 NOT_PRODUCT(reset_evacuation_should_fail();)
5650 }
5651
5652 // Enqueue any remaining references remaining on the STW
5653 // reference processor's discovered lists. We need to do
5654 // this after the card table is cleaned (and verified) as
5655 // the act of enqueueing entries on to the pending list
5656 // will log these updates (and dirty their associated
5657 // cards). We need these updates logged to update any
5658 // RSets.
5659 enqueue_discovered_references(per_thread_states);
5660
5661 redirty_logged_cards();
5662 #if defined(COMPILER2) || INCLUDE_JVMCI
5663 DerivedPointerTable::update_pointers();
5664 #endif
5665 }
5666
5667 void G1CollectedHeap::record_obj_copy_mem_stats() {
5668 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5669 create_g1_evac_summary(&_old_evac_stats));
5670 }
5671
5672 void G1CollectedHeap::free_region(HeapRegion* hr,
5673 FreeRegionList* free_list,
5674 bool par,
5675 bool locked) {
5676 assert(!hr->is_free(), "the region should not be free");
5677 assert(!hr->is_empty(), "the region should not be empty");
5678 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5679 assert(free_list != NULL, "pre-condition");
5680
5681 if (G1VerifyBitmaps) {
5682 MemRegion mr(hr->bottom(), hr->end());
5683 concurrent_mark()->clearRangePrevBitmap(mr);
5684 }
5685
5686 // Clear the card counts for this region.
5687 // Note: we only need to do this if the region is not young
5688 // (since we don't refine cards in young regions).
5689 if (!hr->is_young()) {
5690 _cg1r->hot_card_cache()->reset_card_counts(hr);
5691 }
5692 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5693 free_list->add_ordered(hr);
5694 }
5695
5696 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5697 FreeRegionList* free_list,
5698 bool par) {
5699 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5700 assert(free_list != NULL, "pre-condition");
5701
5702 size_t hr_capacity = hr->capacity();
5703 // We need to read this before we make the region non-humongous,
5704 // otherwise the information will be gone.
5705 uint last_index = hr->last_hc_index();
5706 hr->clear_humongous();
5707 free_region(hr, free_list, par);
5708
5709 uint i = hr->hrm_index() + 1;
5710 while (i < last_index) {
5711 HeapRegion* curr_hr = region_at(i);
5712 assert(curr_hr->is_continues_humongous(), "invariant");
5713 curr_hr->clear_humongous();
5714 free_region(curr_hr, free_list, par);
5715 i += 1;
5716 }
5717 }
5718
5719 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5720 const HeapRegionSetCount& humongous_regions_removed) {
5721 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5722 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5723 _old_set.bulk_remove(old_regions_removed);
5724 _humongous_set.bulk_remove(humongous_regions_removed);
5725 }
5726
5727 }
5728
5729 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5730 assert(list != NULL, "list can't be null");
5731 if (!list->is_empty()) {
5732 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5733 _hrm.insert_list_into_free_list(list);
5734 }
5735 }
5736
5737 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5738 decrease_used(bytes);
5739 }
5740
5741 class G1ParCleanupCTTask : public AbstractGangTask {
5742 G1SATBCardTableModRefBS* _ct_bs;
5743 G1CollectedHeap* _g1h;
5744 HeapRegion* volatile _su_head;
5745 public:
5746 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5747 G1CollectedHeap* g1h) :
5748 AbstractGangTask("G1 Par Cleanup CT Task"),
5749 _ct_bs(ct_bs), _g1h(g1h) { }
5750
5751 void work(uint worker_id) {
5752 HeapRegion* r;
5753 while (r = _g1h->pop_dirty_cards_region()) {
5754 clear_cards(r);
5755 }
5756 }
5757
5758 void clear_cards(HeapRegion* r) {
5759 // Cards of the survivors should have already been dirtied.
5760 if (!r->is_survivor()) {
5761 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5762 }
5763 }
5764 };
5765
5766 #ifndef PRODUCT
5767 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5768 G1CollectedHeap* _g1h;
5769 G1SATBCardTableModRefBS* _ct_bs;
5770 public:
5771 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5772 : _g1h(g1h), _ct_bs(ct_bs) { }
5773 virtual bool doHeapRegion(HeapRegion* r) {
5774 if (r->is_survivor()) {
5775 _g1h->verify_dirty_region(r);
5776 } else {
5777 _g1h->verify_not_dirty_region(r);
5778 }
5779 return false;
5780 }
5781 };
5782
5783 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5784 // All of the region should be clean.
5785 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5786 MemRegion mr(hr->bottom(), hr->end());
5787 ct_bs->verify_not_dirty_region(mr);
5788 }
5789
5790 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5791 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5792 // dirty allocated blocks as they allocate them. The thread that
5793 // retires each region and replaces it with a new one will do a
5794 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5795 // not dirty that area (one less thing to have to do while holding
5796 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5797 // is dirty.
5798 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5799 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5800 if (hr->is_young()) {
5801 ct_bs->verify_g1_young_region(mr);
5802 } else {
5803 ct_bs->verify_dirty_region(mr);
5804 }
5805 }
5806
5807 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5808 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5809 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5810 verify_dirty_region(hr);
5811 }
5812 }
5813
5814 void G1CollectedHeap::verify_dirty_young_regions() {
5815 verify_dirty_young_list(_young_list->first_region());
5816 }
5817
5818 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5819 HeapWord* tams, HeapWord* end) {
5820 guarantee(tams <= end,
5821 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5822 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5823 if (result < end) {
5824 gclog_or_tty->cr();
5825 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5826 bitmap_name, p2i(result));
5827 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5828 bitmap_name, p2i(tams), p2i(end));
5829 return false;
5830 }
5831 return true;
5832 }
5833
5834 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5835 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5836 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5837
5838 HeapWord* bottom = hr->bottom();
5839 HeapWord* ptams = hr->prev_top_at_mark_start();
5840 HeapWord* ntams = hr->next_top_at_mark_start();
5841 HeapWord* end = hr->end();
5842
5843 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5844
5845 bool res_n = true;
5846 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5847 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5848 // if we happen to be in that state.
5849 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5850 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5851 }
5852 if (!res_p || !res_n) {
5853 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5854 HR_FORMAT_PARAMS(hr));
5855 gclog_or_tty->print_cr("#### Caller: %s", caller);
5856 return false;
5857 }
5858 return true;
5859 }
5860
5861 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5862 if (!G1VerifyBitmaps) return;
5863
5864 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5865 }
5866
5867 class G1VerifyBitmapClosure : public HeapRegionClosure {
5868 private:
5869 const char* _caller;
5870 G1CollectedHeap* _g1h;
5871 bool _failures;
5872
5873 public:
5874 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5875 _caller(caller), _g1h(g1h), _failures(false) { }
5876
5877 bool failures() { return _failures; }
5878
5879 virtual bool doHeapRegion(HeapRegion* hr) {
5880 if (hr->is_continues_humongous()) return false;
5881
5882 bool result = _g1h->verify_bitmaps(_caller, hr);
5883 if (!result) {
5884 _failures = true;
5885 }
5886 return false;
5887 }
5888 };
5889
5890 void G1CollectedHeap::check_bitmaps(const char* caller) {
5891 if (!G1VerifyBitmaps) return;
5892
5893 G1VerifyBitmapClosure cl(caller, this);
5894 heap_region_iterate(&cl);
5895 guarantee(!cl.failures(), "bitmap verification");
5896 }
5897
5898 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5899 private:
5900 bool _failures;
5901 public:
5902 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5903
5904 virtual bool doHeapRegion(HeapRegion* hr) {
5905 uint i = hr->hrm_index();
5906 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5907 if (hr->is_humongous()) {
5908 if (hr->in_collection_set()) {
5909 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5910 _failures = true;
5911 return true;
5912 }
5913 if (cset_state.is_in_cset()) {
5914 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5915 _failures = true;
5916 return true;
5917 }
5918 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5919 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5920 _failures = true;
5921 return true;
5922 }
5923 } else {
5924 if (cset_state.is_humongous()) {
5925 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5926 _failures = true;
5927 return true;
5928 }
5929 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5930 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5931 hr->in_collection_set(), cset_state.value(), i);
5932 _failures = true;
5933 return true;
5934 }
5935 if (cset_state.is_in_cset()) {
5936 if (hr->is_young() != (cset_state.is_young())) {
5937 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5938 hr->is_young(), cset_state.value(), i);
5939 _failures = true;
5940 return true;
5941 }
5942 if (hr->is_old() != (cset_state.is_old())) {
5943 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5944 hr->is_old(), cset_state.value(), i);
5945 _failures = true;
5946 return true;
5947 }
5948 }
5949 }
5950 return false;
5951 }
5952
5953 bool failures() const { return _failures; }
5954 };
5955
5956 bool G1CollectedHeap::check_cset_fast_test() {
5957 G1CheckCSetFastTableClosure cl;
5958 _hrm.iterate(&cl);
5959 return !cl.failures();
5960 }
5961 #endif // PRODUCT
5962
5963 void G1CollectedHeap::cleanUpCardTable() {
5964 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5965 double start = os::elapsedTime();
5966
5967 {
5968 // Iterate over the dirty cards region list.
5969 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5970
5971 workers()->run_task(&cleanup_task);
5972 #ifndef PRODUCT
5973 if (G1VerifyCTCleanup || VerifyAfterGC) {
5974 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5975 heap_region_iterate(&cleanup_verifier);
5976 }
5977 #endif
5978 }
5979
5980 double elapsed = os::elapsedTime() - start;
5981 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5982 }
5983
5984 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5985 size_t pre_used = 0;
5986 FreeRegionList local_free_list("Local List for CSet Freeing");
5987
5988 double young_time_ms = 0.0;
5989 double non_young_time_ms = 0.0;
5990
5991 // Since the collection set is a superset of the the young list,
5992 // all we need to do to clear the young list is clear its
5993 // head and length, and unlink any young regions in the code below
5994 _young_list->clear();
5995
5996 G1CollectorPolicy* policy = g1_policy();
5997
5998 double start_sec = os::elapsedTime();
5999 bool non_young = true;
6000
6001 HeapRegion* cur = cs_head;
6002 int age_bound = -1;
6003 size_t rs_lengths = 0;
6004
6005 while (cur != NULL) {
6006 assert(!is_on_master_free_list(cur), "sanity");
6007 if (non_young) {
6008 if (cur->is_young()) {
6009 double end_sec = os::elapsedTime();
6010 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6011 non_young_time_ms += elapsed_ms;
6012
6013 start_sec = os::elapsedTime();
6014 non_young = false;
6015 }
6016 } else {
6017 if (!cur->is_young()) {
6018 double end_sec = os::elapsedTime();
6019 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6020 young_time_ms += elapsed_ms;
6021
6022 start_sec = os::elapsedTime();
6023 non_young = true;
6024 }
6025 }
6026
6027 rs_lengths += cur->rem_set()->occupied_locked();
6028
6029 HeapRegion* next = cur->next_in_collection_set();
6030 assert(cur->in_collection_set(), "bad CS");
6031 cur->set_next_in_collection_set(NULL);
6032 clear_in_cset(cur);
6033
6034 if (cur->is_young()) {
6035 int index = cur->young_index_in_cset();
6036 assert(index != -1, "invariant");
6037 assert((uint) index < policy->young_cset_region_length(), "invariant");
6038 size_t words_survived = _surviving_young_words[index];
6039 cur->record_surv_words_in_group(words_survived);
6040
6041 // At this point the we have 'popped' cur from the collection set
6042 // (linked via next_in_collection_set()) but it is still in the
6043 // young list (linked via next_young_region()). Clear the
6044 // _next_young_region field.
6045 cur->set_next_young_region(NULL);
6046 } else {
6047 int index = cur->young_index_in_cset();
6048 assert(index == -1, "invariant");
6049 }
6050
6051 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6052 (!cur->is_young() && cur->young_index_in_cset() == -1),
6053 "invariant" );
6054
6055 if (!cur->evacuation_failed()) {
6056 MemRegion used_mr = cur->used_region();
6057
6058 // And the region is empty.
6059 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6060 pre_used += cur->used();
6061 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6062 } else {
6063 cur->uninstall_surv_rate_group();
6064 if (cur->is_young()) {
6065 cur->set_young_index_in_cset(-1);
6066 }
6067 cur->set_evacuation_failed(false);
6068 // The region is now considered to be old.
6069 cur->set_old();
6070 // Do some allocation statistics accounting. Regions that failed evacuation
6071 // are always made old, so there is no need to update anything in the young
6072 // gen statistics, but we need to update old gen statistics.
6073 size_t used_words = cur->marked_bytes() / HeapWordSize;
6074 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6075 _old_set.add(cur);
6076 evacuation_info.increment_collectionset_used_after(cur->used());
6077 }
6078 cur = next;
6079 }
6080
6081 evacuation_info.set_regions_freed(local_free_list.length());
6082 policy->record_max_rs_lengths(rs_lengths);
6083 policy->cset_regions_freed();
6084
6085 double end_sec = os::elapsedTime();
6086 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6087
6088 if (non_young) {
6089 non_young_time_ms += elapsed_ms;
6090 } else {
6091 young_time_ms += elapsed_ms;
6092 }
6093
6094 prepend_to_freelist(&local_free_list);
6095 decrement_summary_bytes(pre_used);
6096 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6097 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6098 }
6099
6100 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6101 private:
6102 FreeRegionList* _free_region_list;
6103 HeapRegionSet* _proxy_set;
6104 HeapRegionSetCount _humongous_regions_removed;
6105 size_t _freed_bytes;
6106 public:
6107
6108 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6109 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6110 }
6111
6112 virtual bool doHeapRegion(HeapRegion* r) {
6113 if (!r->is_starts_humongous()) {
6114 return false;
6115 }
6116
6117 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6118
6119 oop obj = (oop)r->bottom();
6120 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6121
6122 // The following checks whether the humongous object is live are sufficient.
6123 // The main additional check (in addition to having a reference from the roots
6124 // or the young gen) is whether the humongous object has a remembered set entry.
6125 //
6126 // A humongous object cannot be live if there is no remembered set for it
6127 // because:
6128 // - there can be no references from within humongous starts regions referencing
6129 // the object because we never allocate other objects into them.
6130 // (I.e. there are no intra-region references that may be missed by the
6131 // remembered set)
6132 // - as soon there is a remembered set entry to the humongous starts region
6133 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6134 // until the end of a concurrent mark.
6135 //
6136 // It is not required to check whether the object has been found dead by marking
6137 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6138 // all objects allocated during that time are considered live.
6139 // SATB marking is even more conservative than the remembered set.
6140 // So if at this point in the collection there is no remembered set entry,
6141 // nobody has a reference to it.
6142 // At the start of collection we flush all refinement logs, and remembered sets
6143 // are completely up-to-date wrt to references to the humongous object.
6144 //
6145 // Other implementation considerations:
6146 // - never consider object arrays at this time because they would pose
6147 // considerable effort for cleaning up the the remembered sets. This is
6148 // required because stale remembered sets might reference locations that
6149 // are currently allocated into.
6150 uint region_idx = r->hrm_index();
6151 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6152 !r->rem_set()->is_empty()) {
6153
6154 if (G1TraceEagerReclaimHumongousObjects) {
6155 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",
6156 region_idx,
6157 (size_t)obj->size() * HeapWordSize,
6158 p2i(r->bottom()),
6159 r->region_num(),
6160 r->rem_set()->occupied(),
6161 r->rem_set()->strong_code_roots_list_length(),
6162 next_bitmap->isMarked(r->bottom()),
6163 g1h->is_humongous_reclaim_candidate(region_idx),
6164 obj->is_typeArray()
6165 );
6166 }
6167
6168 return false;
6169 }
6170
6171 guarantee(obj->is_typeArray(),
6172 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6173 PTR_FORMAT " is not.",
6174 p2i(r->bottom())));
6175
6176 if (G1TraceEagerReclaimHumongousObjects) {
6177 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",
6178 region_idx,
6179 (size_t)obj->size() * HeapWordSize,
6180 p2i(r->bottom()),
6181 r->region_num(),
6182 r->rem_set()->occupied(),
6183 r->rem_set()->strong_code_roots_list_length(),
6184 next_bitmap->isMarked(r->bottom()),
6185 g1h->is_humongous_reclaim_candidate(region_idx),
6186 obj->is_typeArray()
6187 );
6188 }
6189 // Need to clear mark bit of the humongous object if already set.
6190 if (next_bitmap->isMarked(r->bottom())) {
6191 next_bitmap->clear(r->bottom());
6192 }
6193 _freed_bytes += r->used();
6194 r->set_containing_set(NULL);
6195 _humongous_regions_removed.increment(1u, r->capacity());
6196 g1h->free_humongous_region(r, _free_region_list, false);
6197
6198 return false;
6199 }
6200
6201 HeapRegionSetCount& humongous_free_count() {
6202 return _humongous_regions_removed;
6203 }
6204
6205 size_t bytes_freed() const {
6206 return _freed_bytes;
6207 }
6208
6209 size_t humongous_reclaimed() const {
6210 return _humongous_regions_removed.length();
6211 }
6212 };
6213
6214 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6215 assert_at_safepoint(true);
6216
6217 if (!G1EagerReclaimHumongousObjects ||
6218 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6219 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6220 return;
6221 }
6222
6223 double start_time = os::elapsedTime();
6224
6225 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6226
6227 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6228 heap_region_iterate(&cl);
6229
6230 HeapRegionSetCount empty_set;
6231 remove_from_old_sets(empty_set, cl.humongous_free_count());
6232
6233 G1HRPrinter* hrp = hr_printer();
6234 if (hrp->is_active()) {
6235 FreeRegionListIterator iter(&local_cleanup_list);
6236 while (iter.more_available()) {
6237 HeapRegion* hr = iter.get_next();
6238 hrp->cleanup(hr);
6239 }
6240 }
6241
6242 prepend_to_freelist(&local_cleanup_list);
6243 decrement_summary_bytes(cl.bytes_freed());
6244
6245 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6246 cl.humongous_reclaimed());
6247 }
6248
6249 // This routine is similar to the above but does not record
6250 // any policy statistics or update free lists; we are abandoning
6251 // the current incremental collection set in preparation of a
6252 // full collection. After the full GC we will start to build up
6253 // the incremental collection set again.
6254 // This is only called when we're doing a full collection
6255 // and is immediately followed by the tearing down of the young list.
6256
6257 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6258 HeapRegion* cur = cs_head;
6259
6260 while (cur != NULL) {
6261 HeapRegion* next = cur->next_in_collection_set();
6262 assert(cur->in_collection_set(), "bad CS");
6263 cur->set_next_in_collection_set(NULL);
6264 clear_in_cset(cur);
6265 cur->set_young_index_in_cset(-1);
6266 cur = next;
6267 }
6268 }
6269
6270 void G1CollectedHeap::set_free_regions_coming() {
6271 if (G1ConcRegionFreeingVerbose) {
6272 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6273 "setting free regions coming");
6274 }
6275
6276 assert(!free_regions_coming(), "pre-condition");
6277 _free_regions_coming = true;
6278 }
6279
6280 void G1CollectedHeap::reset_free_regions_coming() {
6281 assert(free_regions_coming(), "pre-condition");
6282
6283 {
6284 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6285 _free_regions_coming = false;
6286 SecondaryFreeList_lock->notify_all();
6287 }
6288
6289 if (G1ConcRegionFreeingVerbose) {
6290 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6291 "reset free regions coming");
6292 }
6293 }
6294
6295 void G1CollectedHeap::wait_while_free_regions_coming() {
6296 // Most of the time we won't have to wait, so let's do a quick test
6297 // first before we take the lock.
6298 if (!free_regions_coming()) {
6299 return;
6300 }
6301
6302 if (G1ConcRegionFreeingVerbose) {
6303 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6304 "waiting for free regions");
6305 }
6306
6307 {
6308 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6309 while (free_regions_coming()) {
6310 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6311 }
6312 }
6313
6314 if (G1ConcRegionFreeingVerbose) {
6315 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6316 "done waiting for free regions");
6317 }
6318 }
6319
6320 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6321 return _allocator->is_retained_old_region(hr);
6322 }
6323
6324 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6325 _young_list->push_region(hr);
6326 }
6327
6328 class NoYoungRegionsClosure: public HeapRegionClosure {
6329 private:
6330 bool _success;
6331 public:
6332 NoYoungRegionsClosure() : _success(true) { }
6333 bool doHeapRegion(HeapRegion* r) {
6334 if (r->is_young()) {
6335 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6336 p2i(r->bottom()), p2i(r->end()));
6337 _success = false;
6338 }
6339 return false;
6340 }
6341 bool success() { return _success; }
6342 };
6343
6344 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6345 bool ret = _young_list->check_list_empty(check_sample);
6346
6347 if (check_heap) {
6348 NoYoungRegionsClosure closure;
6349 heap_region_iterate(&closure);
6350 ret = ret && closure.success();
6351 }
6352
6353 return ret;
6354 }
6355
6356 class TearDownRegionSetsClosure : public HeapRegionClosure {
6357 private:
6358 HeapRegionSet *_old_set;
6359
6360 public:
6361 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6362
6363 bool doHeapRegion(HeapRegion* r) {
6364 if (r->is_old()) {
6365 _old_set->remove(r);
6366 } else {
6367 // We ignore free regions, we'll empty the free list afterwards.
6368 // We ignore young regions, we'll empty the young list afterwards.
6369 // We ignore humongous regions, we're not tearing down the
6370 // humongous regions set.
6371 assert(r->is_free() || r->is_young() || r->is_humongous(),
6372 "it cannot be another type");
6373 }
6374 return false;
6375 }
6376
6377 ~TearDownRegionSetsClosure() {
6378 assert(_old_set->is_empty(), "post-condition");
6379 }
6380 };
6381
6382 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6383 assert_at_safepoint(true /* should_be_vm_thread */);
6384
6385 if (!free_list_only) {
6386 TearDownRegionSetsClosure cl(&_old_set);
6387 heap_region_iterate(&cl);
6388
6389 // Note that emptying the _young_list is postponed and instead done as
6390 // the first step when rebuilding the regions sets again. The reason for
6391 // this is that during a full GC string deduplication needs to know if
6392 // a collected region was young or old when the full GC was initiated.
6393 }
6394 _hrm.remove_all_free_regions();
6395 }
6396
6397 void G1CollectedHeap::increase_used(size_t bytes) {
6398 _summary_bytes_used += bytes;
6399 }
6400
6401 void G1CollectedHeap::decrease_used(size_t bytes) {
6402 assert(_summary_bytes_used >= bytes,
6403 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6404 _summary_bytes_used, bytes));
6405 _summary_bytes_used -= bytes;
6406 }
6407
6408 void G1CollectedHeap::set_used(size_t bytes) {
6409 _summary_bytes_used = bytes;
6410 }
6411
6412 class RebuildRegionSetsClosure : public HeapRegionClosure {
6413 private:
6414 bool _free_list_only;
6415 HeapRegionSet* _old_set;
6416 HeapRegionManager* _hrm;
6417 size_t _total_used;
6418
6419 public:
6420 RebuildRegionSetsClosure(bool free_list_only,
6421 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6422 _free_list_only(free_list_only),
6423 _old_set(old_set), _hrm(hrm), _total_used(0) {
6424 assert(_hrm->num_free_regions() == 0, "pre-condition");
6425 if (!free_list_only) {
6426 assert(_old_set->is_empty(), "pre-condition");
6427 }
6428 }
6429
6430 bool doHeapRegion(HeapRegion* r) {
6431 if (r->is_continues_humongous()) {
6432 return false;
6433 }
6434
6435 if (r->is_empty()) {
6436 // Add free regions to the free list
6437 r->set_free();
6438 r->set_allocation_context(AllocationContext::system());
6439 _hrm->insert_into_free_list(r);
6440 } else if (!_free_list_only) {
6441 assert(!r->is_young(), "we should not come across young regions");
6442
6443 if (r->is_humongous()) {
6444 // We ignore humongous regions. We left the humongous set unchanged.
6445 } else {
6446 // Objects that were compacted would have ended up on regions
6447 // that were previously old or free. Archive regions (which are
6448 // old) will not have been touched.
6449 assert(r->is_free() || r->is_old(), "invariant");
6450 // We now consider them old, so register as such. Leave
6451 // archive regions set that way, however, while still adding
6452 // them to the old set.
6453 if (!r->is_archive()) {
6454 r->set_old();
6455 }
6456 _old_set->add(r);
6457 }
6458 _total_used += r->used();
6459 }
6460
6461 return false;
6462 }
6463
6464 size_t total_used() {
6465 return _total_used;
6466 }
6467 };
6468
6469 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6470 assert_at_safepoint(true /* should_be_vm_thread */);
6471
6472 if (!free_list_only) {
6473 _young_list->empty_list();
6474 }
6475
6476 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6477 heap_region_iterate(&cl);
6478
6479 if (!free_list_only) {
6480 set_used(cl.total_used());
6481 if (_archive_allocator != NULL) {
6482 _archive_allocator->clear_used();
6483 }
6484 }
6485 assert(used_unlocked() == recalculate_used(),
6486 err_msg("inconsistent used_unlocked(), "
6487 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6488 used_unlocked(), recalculate_used()));
6489 }
6490
6491 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6492 _refine_cte_cl->set_concurrent(concurrent);
6493 }
6494
6495 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6496 HeapRegion* hr = heap_region_containing(p);
6497 return hr->is_in(p);
6498 }
6499
6500 // Methods for the mutator alloc region
6501
6502 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6503 bool force) {
6504 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6505 assert(!force || g1_policy()->can_expand_young_list(),
6506 "if force is true we should be able to expand the young list");
6507 bool young_list_full = g1_policy()->is_young_list_full();
6508 if (force || !young_list_full) {
6509 HeapRegion* new_alloc_region = new_region(word_size,
6510 false /* is_old */,
6511 false /* do_expand */);
6512 if (new_alloc_region != NULL) {
6513 set_region_short_lived_locked(new_alloc_region);
6514 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6515 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6516 return new_alloc_region;
6517 }
6518 }
6519 return NULL;
6520 }
6521
6522 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6523 size_t allocated_bytes) {
6524 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6525 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6526
6527 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6528 increase_used(allocated_bytes);
6529 _hr_printer.retire(alloc_region);
6530 // We update the eden sizes here, when the region is retired,
6531 // instead of when it's allocated, since this is the point that its
6532 // used space has been recored in _summary_bytes_used.
6533 g1mm()->update_eden_size();
6534 }
6535
6536 // Methods for the GC alloc regions
6537
6538 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6539 uint count,
6540 InCSetState dest) {
6541 assert(FreeList_lock->owned_by_self(), "pre-condition");
6542
6543 if (count < g1_policy()->max_regions(dest)) {
6544 const bool is_survivor = (dest.is_young());
6545 HeapRegion* new_alloc_region = new_region(word_size,
6546 !is_survivor,
6547 true /* do_expand */);
6548 if (new_alloc_region != NULL) {
6549 // We really only need to do this for old regions given that we
6550 // should never scan survivors. But it doesn't hurt to do it
6551 // for survivors too.
6552 new_alloc_region->record_timestamp();
6553 if (is_survivor) {
6554 new_alloc_region->set_survivor();
6555 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6556 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6557 } else {
6558 new_alloc_region->set_old();
6559 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6560 check_bitmaps("Old Region Allocation", new_alloc_region);
6561 }
6562 bool during_im = collector_state()->during_initial_mark_pause();
6563 new_alloc_region->note_start_of_copying(during_im);
6564 return new_alloc_region;
6565 }
6566 }
6567 return NULL;
6568 }
6569
6570 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6571 size_t allocated_bytes,
6572 InCSetState dest) {
6573 bool during_im = collector_state()->during_initial_mark_pause();
6574 alloc_region->note_end_of_copying(during_im);
6575 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6576 if (dest.is_young()) {
6577 young_list()->add_survivor_region(alloc_region);
6578 } else {
6579 _old_set.add(alloc_region);
6580 }
6581 _hr_printer.retire(alloc_region);
6582 }
6583
6584 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6585 bool expanded = false;
6586 uint index = _hrm.find_highest_free(&expanded);
6587
6588 if (index != G1_NO_HRM_INDEX) {
6589 if (expanded) {
6590 ergo_verbose1(ErgoHeapSizing,
6591 "attempt heap expansion",
6592 ergo_format_reason("requested address range outside heap bounds")
6593 ergo_format_byte("region size"),
6594 HeapRegion::GrainWords * HeapWordSize);
6595 }
6596 _hrm.allocate_free_regions_starting_at(index, 1);
6597 return region_at(index);
6598 }
6599 return NULL;
6600 }
6601
6602 // Heap region set verification
6603
6604 class VerifyRegionListsClosure : public HeapRegionClosure {
6605 private:
6606 HeapRegionSet* _old_set;
6607 HeapRegionSet* _humongous_set;
6608 HeapRegionManager* _hrm;
6609
6610 public:
6611 HeapRegionSetCount _old_count;
6612 HeapRegionSetCount _humongous_count;
6613 HeapRegionSetCount _free_count;
6614
6615 VerifyRegionListsClosure(HeapRegionSet* old_set,
6616 HeapRegionSet* humongous_set,
6617 HeapRegionManager* hrm) :
6618 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6619 _old_count(), _humongous_count(), _free_count(){ }
6620
6621 bool doHeapRegion(HeapRegion* hr) {
6622 if (hr->is_continues_humongous()) {
6623 return false;
6624 }
6625
6626 if (hr->is_young()) {
6627 // TODO
6628 } else if (hr->is_starts_humongous()) {
6629 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6630 _humongous_count.increment(1u, hr->capacity());
6631 } else if (hr->is_empty()) {
6632 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6633 _free_count.increment(1u, hr->capacity());
6634 } else if (hr->is_old()) {
6635 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6636 _old_count.increment(1u, hr->capacity());
6637 } else {
6638 // There are no other valid region types. Check for one invalid
6639 // one we can identify: pinned without old or humongous set.
6640 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6641 ShouldNotReachHere();
6642 }
6643 return false;
6644 }
6645
6646 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6647 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6648 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6649 old_set->total_capacity_bytes(), _old_count.capacity()));
6650
6651 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6652 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6653 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6654
6655 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()));
6656 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6657 free_list->total_capacity_bytes(), _free_count.capacity()));
6658 }
6659 };
6660
6661 void G1CollectedHeap::verify_region_sets() {
6662 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6663
6664 // First, check the explicit lists.
6665 _hrm.verify();
6666 {
6667 // Given that a concurrent operation might be adding regions to
6668 // the secondary free list we have to take the lock before
6669 // verifying it.
6670 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6671 _secondary_free_list.verify_list();
6672 }
6673
6674 // If a concurrent region freeing operation is in progress it will
6675 // be difficult to correctly attributed any free regions we come
6676 // across to the correct free list given that they might belong to
6677 // one of several (free_list, secondary_free_list, any local lists,
6678 // etc.). So, if that's the case we will skip the rest of the
6679 // verification operation. Alternatively, waiting for the concurrent
6680 // operation to complete will have a non-trivial effect on the GC's
6681 // operation (no concurrent operation will last longer than the
6682 // interval between two calls to verification) and it might hide
6683 // any issues that we would like to catch during testing.
6684 if (free_regions_coming()) {
6685 return;
6686 }
6687
6688 // Make sure we append the secondary_free_list on the free_list so
6689 // that all free regions we will come across can be safely
6690 // attributed to the free_list.
6691 append_secondary_free_list_if_not_empty_with_lock();
6692
6693 // Finally, make sure that the region accounting in the lists is
6694 // consistent with what we see in the heap.
6695
6696 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6697 heap_region_iterate(&cl);
6698 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6699 }
6700
6701 // Optimized nmethod scanning
6702
6703 class RegisterNMethodOopClosure: public OopClosure {
6704 G1CollectedHeap* _g1h;
6705 nmethod* _nm;
6706
6707 template <class T> void do_oop_work(T* p) {
6708 T heap_oop = oopDesc::load_heap_oop(p);
6709 if (!oopDesc::is_null(heap_oop)) {
6710 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6711 HeapRegion* hr = _g1h->heap_region_containing(obj);
6712 assert(!hr->is_continues_humongous(),
6713 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6714 " starting at " HR_FORMAT,
6715 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6716
6717 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6718 hr->add_strong_code_root_locked(_nm);
6719 }
6720 }
6721
6722 public:
6723 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6724 _g1h(g1h), _nm(nm) {}
6725
6726 void do_oop(oop* p) { do_oop_work(p); }
6727 void do_oop(narrowOop* p) { do_oop_work(p); }
6728 };
6729
6730 class UnregisterNMethodOopClosure: public OopClosure {
6731 G1CollectedHeap* _g1h;
6732 nmethod* _nm;
6733
6734 template <class T> void do_oop_work(T* p) {
6735 T heap_oop = oopDesc::load_heap_oop(p);
6736 if (!oopDesc::is_null(heap_oop)) {
6737 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6738 HeapRegion* hr = _g1h->heap_region_containing(obj);
6739 assert(!hr->is_continues_humongous(),
6740 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6741 " starting at " HR_FORMAT,
6742 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6743
6744 hr->remove_strong_code_root(_nm);
6745 }
6746 }
6747
6748 public:
6749 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6750 _g1h(g1h), _nm(nm) {}
6751
6752 void do_oop(oop* p) { do_oop_work(p); }
6753 void do_oop(narrowOop* p) { do_oop_work(p); }
6754 };
6755
6756 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6757 CollectedHeap::register_nmethod(nm);
6758
6759 guarantee(nm != NULL, "sanity");
6760 RegisterNMethodOopClosure reg_cl(this, nm);
6761 nm->oops_do(®_cl);
6762 }
6763
6764 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6765 CollectedHeap::unregister_nmethod(nm);
6766
6767 guarantee(nm != NULL, "sanity");
6768 UnregisterNMethodOopClosure reg_cl(this, nm);
6769 nm->oops_do(®_cl, true);
6770 }
6771
6772 void G1CollectedHeap::purge_code_root_memory() {
6773 double purge_start = os::elapsedTime();
6774 G1CodeRootSet::purge();
6775 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6776 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6777 }
6778
6779 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6780 G1CollectedHeap* _g1h;
6781
6782 public:
6783 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6784 _g1h(g1h) {}
6785
6786 void do_code_blob(CodeBlob* cb) {
6787 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6788 if (nm == NULL) {
6789 return;
6790 }
6791
6792 if (ScavengeRootsInCode) {
6793 _g1h->register_nmethod(nm);
6794 }
6795 }
6796 };
6797
6798 void G1CollectedHeap::rebuild_strong_code_roots() {
6799 RebuildStrongCodeRootClosure blob_cl(this);
6800 CodeCache::blobs_do(&blob_cl);
6801 }