1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1AllocRegion.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "memory/allocation.hpp"
65 #include "memory/iterator.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/orderAccess.inline.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "utilities/globalDefinitions.hpp"
71 #include "utilities/stack.inline.hpp"
72
73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
74
75 // turn it on so that the contents of the young list (scan-only /
76 // to-be-collected) are printed at "strategic" points before / during
77 // / after the collection --- this is useful for debugging
78 #define YOUNG_LIST_VERBOSE 0
79 // CURRENT STATUS
80 // This file is under construction. Search for "FIXME".
81
82 // INVARIANTS/NOTES
83 //
84 // All allocation activity covered by the G1CollectedHeap interface is
85 // serialized by acquiring the HeapLock. This happens in mem_allocate
86 // and allocate_new_tlab, which are the "entry" points to the
87 // allocation code from the rest of the JVM. (Note that this does not
88 // apply to TLAB allocation, which is not part of this interface: it
89 // is done by clients of this interface.)
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 bool _concurrent;
95 public:
96 RefineCardTableEntryClosure() : _concurrent(true) { }
97
98 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
99 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
100 // This path is executed by the concurrent refine or mutator threads,
101 // concurrently, and so we do not care if card_ptr contains references
102 // that point into the collection set.
103 assert(!oops_into_cset, "should be");
104
105 if (_concurrent && SuspendibleThreadSet::should_yield()) {
106 // Caller will actually yield.
107 return false;
108 }
109 // Otherwise, we finished successfully; return true.
110 return true;
111 }
112
113 void set_concurrent(bool b) { _concurrent = b; }
114 };
115
116
117 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
118 private:
119 size_t _num_processed;
120
121 public:
122 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
123
124 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
125 *card_ptr = CardTableModRefBS::dirty_card_val();
126 _num_processed++;
127 return true;
128 }
129
130 size_t num_processed() const { return _num_processed; }
131 };
132
133 YoungList::YoungList(G1CollectedHeap* g1h) :
134 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
135 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
136 guarantee(check_list_empty(false), "just making sure...");
137 }
138
139 void YoungList::push_region(HeapRegion *hr) {
140 assert(!hr->is_young(), "should not already be young");
141 assert(hr->get_next_young_region() == NULL, "cause it should!");
142
143 hr->set_next_young_region(_head);
144 _head = hr;
145
146 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
147 ++_length;
148 }
149
150 void YoungList::add_survivor_region(HeapRegion* hr) {
151 assert(hr->is_survivor(), "should be flagged as survivor region");
152 assert(hr->get_next_young_region() == NULL, "cause it should!");
153
154 hr->set_next_young_region(_survivor_head);
155 if (_survivor_head == NULL) {
156 _survivor_tail = hr;
157 }
158 _survivor_head = hr;
159 ++_survivor_length;
160 }
161
162 void YoungList::empty_list(HeapRegion* list) {
163 while (list != NULL) {
164 HeapRegion* next = list->get_next_young_region();
165 list->set_next_young_region(NULL);
166 list->uninstall_surv_rate_group();
167 // This is called before a Full GC and all the non-empty /
168 // non-humongous regions at the end of the Full GC will end up as
169 // old anyway.
170 list->set_old();
171 list = next;
172 }
173 }
174
175 void YoungList::empty_list() {
176 assert(check_list_well_formed(), "young list should be well formed");
177
178 empty_list(_head);
179 _head = NULL;
180 _length = 0;
181
182 empty_list(_survivor_head);
183 _survivor_head = NULL;
184 _survivor_tail = NULL;
185 _survivor_length = 0;
186
187 _last_sampled_rs_lengths = 0;
188
189 assert(check_list_empty(false), "just making sure...");
190 }
191
192 bool YoungList::check_list_well_formed() {
193 bool ret = true;
194
195 uint length = 0;
196 HeapRegion* curr = _head;
197 HeapRegion* last = NULL;
198 while (curr != NULL) {
199 if (!curr->is_young()) {
200 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
201 "incorrectly tagged (y: %d, surv: %d)",
202 p2i(curr->bottom()), p2i(curr->end()),
203 curr->is_young(), curr->is_survivor());
204 ret = false;
205 }
206 ++length;
207 last = curr;
208 curr = curr->get_next_young_region();
209 }
210 ret = ret && (length == _length);
211
212 if (!ret) {
213 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
214 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
215 length, _length);
216 }
217
218 return ret;
219 }
220
221 bool YoungList::check_list_empty(bool check_sample) {
222 bool ret = true;
223
224 if (_length != 0) {
225 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
226 _length);
227 ret = false;
228 }
229 if (check_sample && _last_sampled_rs_lengths != 0) {
230 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
231 ret = false;
232 }
233 if (_head != NULL) {
234 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
235 ret = false;
236 }
237 if (!ret) {
238 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
239 }
240
241 return ret;
242 }
243
244 void
245 YoungList::rs_length_sampling_init() {
246 _sampled_rs_lengths = 0;
247 _curr = _head;
248 }
249
250 bool
251 YoungList::rs_length_sampling_more() {
252 return _curr != NULL;
253 }
254
255 void
256 YoungList::rs_length_sampling_next() {
257 assert( _curr != NULL, "invariant" );
258 size_t rs_length = _curr->rem_set()->occupied();
259
260 _sampled_rs_lengths += rs_length;
261
262 // The current region may not yet have been added to the
263 // incremental collection set (it gets added when it is
264 // retired as the current allocation region).
265 if (_curr->in_collection_set()) {
266 // Update the collection set policy information for this region
267 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
268 }
269
270 _curr = _curr->get_next_young_region();
271 if (_curr == NULL) {
272 _last_sampled_rs_lengths = _sampled_rs_lengths;
273 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
274 }
275 }
276
277 void
278 YoungList::reset_auxilary_lists() {
279 guarantee( is_empty(), "young list should be empty" );
280 assert(check_list_well_formed(), "young list should be well formed");
281
282 // Add survivor regions to SurvRateGroup.
283 _g1h->g1_policy()->note_start_adding_survivor_regions();
284 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
285
286 int young_index_in_cset = 0;
287 for (HeapRegion* curr = _survivor_head;
288 curr != NULL;
289 curr = curr->get_next_young_region()) {
290 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
291
292 // The region is a non-empty survivor so let's add it to
293 // the incremental collection set for the next evacuation
294 // pause.
295 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
296 young_index_in_cset += 1;
297 }
298 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
299 _g1h->g1_policy()->note_stop_adding_survivor_regions();
300
301 _head = _survivor_head;
302 _length = _survivor_length;
303 if (_survivor_head != NULL) {
304 assert(_survivor_tail != NULL, "cause it shouldn't be");
305 assert(_survivor_length > 0, "invariant");
306 _survivor_tail->set_next_young_region(NULL);
307 }
308
309 // Don't clear the survivor list handles until the start of
310 // the next evacuation pause - we need it in order to re-tag
311 // the survivor regions from this evacuation pause as 'young'
312 // at the start of the next.
313
314 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
315
316 assert(check_list_well_formed(), "young list should be well formed");
317 }
318
319 void YoungList::print() {
320 HeapRegion* lists[] = {_head, _survivor_head};
321 const char* names[] = {"YOUNG", "SURVIVOR"};
322
323 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
324 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
325 HeapRegion *curr = lists[list];
326 if (curr == NULL)
327 gclog_or_tty->print_cr(" empty");
328 while (curr != NULL) {
329 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
330 HR_FORMAT_PARAMS(curr),
331 p2i(curr->prev_top_at_mark_start()),
332 p2i(curr->next_top_at_mark_start()),
333 curr->age_in_surv_rate_group_cond());
334 curr = curr->get_next_young_region();
335 }
336 }
337
338 gclog_or_tty->cr();
339 }
340
341 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
342 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
343 }
344
345 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
346 // The from card cache is not the memory that is actually committed. So we cannot
347 // take advantage of the zero_filled parameter.
348 reset_from_card_cache(start_idx, num_regions);
349 }
350
351 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
352 {
353 // Claim the right to put the region on the dirty cards region list
354 // by installing a self pointer.
355 HeapRegion* next = hr->get_next_dirty_cards_region();
356 if (next == NULL) {
357 HeapRegion* res = (HeapRegion*)
358 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
359 NULL);
360 if (res == NULL) {
361 HeapRegion* head;
362 do {
363 // Put the region to the dirty cards region list.
364 head = _dirty_cards_region_list;
365 next = (HeapRegion*)
366 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
367 if (next == head) {
368 assert(hr->get_next_dirty_cards_region() == hr,
369 "hr->get_next_dirty_cards_region() != hr");
370 if (next == NULL) {
371 // The last region in the list points to itself.
372 hr->set_next_dirty_cards_region(hr);
373 } else {
374 hr->set_next_dirty_cards_region(next);
375 }
376 }
377 } while (next != head);
378 }
379 }
380 }
381
382 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
383 {
384 HeapRegion* head;
385 HeapRegion* hr;
386 do {
387 head = _dirty_cards_region_list;
388 if (head == NULL) {
389 return NULL;
390 }
391 HeapRegion* new_head = head->get_next_dirty_cards_region();
392 if (head == new_head) {
393 // The last region.
394 new_head = NULL;
395 }
396 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
397 head);
398 } while (hr != head);
399 assert(hr != NULL, "invariant");
400 hr->set_next_dirty_cards_region(NULL);
401 return hr;
402 }
403
404 // Returns true if the reference points to an object that
405 // can move in an incremental collection.
406 bool G1CollectedHeap::is_scavengable(const void* p) {
407 HeapRegion* hr = heap_region_containing(p);
408 return !hr->is_pinned();
409 }
410
411 // Private methods.
412
413 HeapRegion*
414 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
415 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
416 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
417 if (!_secondary_free_list.is_empty()) {
418 if (G1ConcRegionFreeingVerbose) {
419 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
420 "secondary_free_list has %u entries",
421 _secondary_free_list.length());
422 }
423 // It looks as if there are free regions available on the
424 // secondary_free_list. Let's move them to the free_list and try
425 // again to allocate from it.
426 append_secondary_free_list();
427
428 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
429 "empty we should have moved at least one entry to the free_list");
430 HeapRegion* res = _hrm.allocate_free_region(is_old);
431 if (G1ConcRegionFreeingVerbose) {
432 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
433 "allocated " HR_FORMAT " from secondary_free_list",
434 HR_FORMAT_PARAMS(res));
435 }
436 return res;
437 }
438
439 // Wait here until we get notified either when (a) there are no
440 // more free regions coming or (b) some regions have been moved on
441 // the secondary_free_list.
442 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
443 }
444
445 if (G1ConcRegionFreeingVerbose) {
446 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
447 "could not allocate from secondary_free_list");
448 }
449 return NULL;
450 }
451
452 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
453 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
454 "the only time we use this to allocate a humongous region is "
455 "when we are allocating a single humongous region");
456
457 HeapRegion* res;
458 if (G1StressConcRegionFreeing) {
459 if (!_secondary_free_list.is_empty()) {
460 if (G1ConcRegionFreeingVerbose) {
461 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
462 "forced to look at the secondary_free_list");
463 }
464 res = new_region_try_secondary_free_list(is_old);
465 if (res != NULL) {
466 return res;
467 }
468 }
469 }
470
471 res = _hrm.allocate_free_region(is_old);
472
473 if (res == NULL) {
474 if (G1ConcRegionFreeingVerbose) {
475 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
476 "res == NULL, trying the secondary_free_list");
477 }
478 res = new_region_try_secondary_free_list(is_old);
479 }
480 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
481 // Currently, only attempts to allocate GC alloc regions set
482 // do_expand to true. So, we should only reach here during a
483 // safepoint. If this assumption changes we might have to
484 // reconsider the use of _expand_heap_after_alloc_failure.
485 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
486
487 ergo_verbose1(ErgoHeapSizing,
488 "attempt heap expansion",
489 ergo_format_reason("region allocation request failed")
490 ergo_format_byte("allocation request"),
491 word_size * HeapWordSize);
492 if (expand(word_size * HeapWordSize)) {
493 // Given that expand() succeeded in expanding the heap, and we
494 // always expand the heap by an amount aligned to the heap
495 // region size, the free list should in theory not be empty.
496 // In either case allocate_free_region() will check for NULL.
497 res = _hrm.allocate_free_region(is_old);
498 } else {
499 _expand_heap_after_alloc_failure = false;
500 }
501 }
502 return res;
503 }
504
505 HeapWord*
506 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
507 uint num_regions,
508 size_t word_size,
509 AllocationContext_t context) {
510 assert(first != G1_NO_HRM_INDEX, "pre-condition");
511 assert(is_humongous(word_size), "word_size should be humongous");
512 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
513
514 // Index of last region in the series + 1.
515 uint last = first + num_regions;
516
517 // We need to initialize the region(s) we just discovered. This is
518 // a bit tricky given that it can happen concurrently with
519 // refinement threads refining cards on these regions and
520 // potentially wanting to refine the BOT as they are scanning
521 // those cards (this can happen shortly after a cleanup; see CR
522 // 6991377). So we have to set up the region(s) carefully and in
523 // a specific order.
524
525 // The word size sum of all the regions we will allocate.
526 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
527 assert(word_size <= word_size_sum, "sanity");
528
529 // This will be the "starts humongous" region.
530 HeapRegion* first_hr = region_at(first);
531 // The header of the new object will be placed at the bottom of
532 // the first region.
533 HeapWord* new_obj = first_hr->bottom();
534 // This will be the new end of the first region in the series that
535 // should also match the end of the last region in the series.
536 HeapWord* new_end = new_obj + word_size_sum;
537 // This will be the new top of the first region that will reflect
538 // this allocation.
539 HeapWord* new_top = new_obj + word_size;
540
541 // First, we need to zero the header of the space that we will be
542 // allocating. When we update top further down, some refinement
543 // threads might try to scan the region. By zeroing the header we
544 // ensure that any thread that will try to scan the region will
545 // come across the zero klass word and bail out.
546 //
547 // NOTE: It would not have been correct to have used
548 // CollectedHeap::fill_with_object() and make the space look like
549 // an int array. The thread that is doing the allocation will
550 // later update the object header to a potentially different array
551 // type and, for a very short period of time, the klass and length
552 // fields will be inconsistent. This could cause a refinement
553 // thread to calculate the object size incorrectly.
554 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
555
556 // We will set up the first region as "starts humongous". This
557 // will also update the BOT covering all the regions to reflect
558 // that there is a single object that starts at the bottom of the
559 // first region.
560 first_hr->set_starts_humongous(new_top, new_end);
561 first_hr->set_allocation_context(context);
562 // Then, if there are any, we will set up the "continues
563 // humongous" regions.
564 HeapRegion* hr = NULL;
565 for (uint i = first + 1; i < last; ++i) {
566 hr = region_at(i);
567 hr->set_continues_humongous(first_hr);
568 hr->set_allocation_context(context);
569 }
570 // If we have "continues humongous" regions (hr != NULL), then the
571 // end of the last one should match new_end.
572 assert(hr == NULL || hr->end() == new_end, "sanity");
573
574 // Up to this point no concurrent thread would have been able to
575 // do any scanning on any region in this series. All the top
576 // fields still point to bottom, so the intersection between
577 // [bottom,top] and [card_start,card_end] will be empty. Before we
578 // update the top fields, we'll do a storestore to make sure that
579 // no thread sees the update to top before the zeroing of the
580 // object header and the BOT initialization.
581 OrderAccess::storestore();
582
583 // Now that the BOT and the object header have been initialized,
584 // we can update top of the "starts humongous" region.
585 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
586 "new_top should be in this region");
587 first_hr->set_top(new_top);
588 if (_hr_printer.is_active()) {
589 HeapWord* bottom = first_hr->bottom();
590 HeapWord* end = first_hr->orig_end();
591 if ((first + 1) == last) {
592 // the series has a single humongous region
593 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
594 } else {
595 // the series has more than one humongous regions
596 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
597 }
598 }
599
600 // Now, we will update the top fields of the "continues humongous"
601 // regions. The reason we need to do this is that, otherwise,
602 // these regions would look empty and this will confuse parts of
603 // G1. For example, the code that looks for a consecutive number
604 // of empty regions will consider them empty and try to
605 // re-allocate them. We can extend is_empty() to also include
606 // !is_continues_humongous(), but it is easier to just update the top
607 // fields here. The way we set top for all regions (i.e., top ==
608 // end for all regions but the last one, top == new_top for the
609 // last one) is actually used when we will free up the humongous
610 // region in free_humongous_region().
611 hr = NULL;
612 for (uint i = first + 1; i < last; ++i) {
613 hr = region_at(i);
614 if ((i + 1) == last) {
615 // last continues humongous region
616 assert(hr->bottom() < new_top && new_top <= hr->end(),
617 "new_top should fall on this region");
618 hr->set_top(new_top);
619 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
620 } else {
621 // not last one
622 assert(new_top > hr->end(), "new_top should be above this region");
623 hr->set_top(hr->end());
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
625 }
626 }
627 // If we have continues humongous regions (hr != NULL), then the
628 // end of the last one should match new_end and its top should
629 // match new_top.
630 assert(hr == NULL ||
631 (hr->end() == new_end && hr->top() == new_top), "sanity");
632 check_bitmaps("Humongous Region Allocation", first_hr);
633
634 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
635 _allocator->increase_used(first_hr->used());
636 _humongous_set.add(first_hr);
637
638 return new_obj;
639 }
640
641 // If could fit into free regions w/o expansion, try.
642 // Otherwise, if can expand, do so.
643 // Otherwise, if using ex regions might help, try with ex given back.
644 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
645 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
646
647 verify_region_sets_optional();
648
649 uint first = G1_NO_HRM_INDEX;
650 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
651
652 if (obj_regions == 1) {
653 // Only one region to allocate, try to use a fast path by directly allocating
654 // from the free lists. Do not try to expand here, we will potentially do that
655 // later.
656 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
657 if (hr != NULL) {
658 first = hr->hrm_index();
659 }
660 } else {
661 // We can't allocate humongous regions spanning more than one region while
662 // cleanupComplete() is running, since some of the regions we find to be
663 // empty might not yet be added to the free list. It is not straightforward
664 // to know in which list they are on so that we can remove them. We only
665 // need to do this if we need to allocate more than one region to satisfy the
666 // current humongous allocation request. If we are only allocating one region
667 // we use the one-region region allocation code (see above), that already
668 // potentially waits for regions from the secondary free list.
669 wait_while_free_regions_coming();
670 append_secondary_free_list_if_not_empty_with_lock();
671
672 // Policy: Try only empty regions (i.e. already committed first). Maybe we
673 // are lucky enough to find some.
674 first = _hrm.find_contiguous_only_empty(obj_regions);
675 if (first != G1_NO_HRM_INDEX) {
676 _hrm.allocate_free_regions_starting_at(first, obj_regions);
677 }
678 }
679
680 if (first == G1_NO_HRM_INDEX) {
681 // Policy: We could not find enough regions for the humongous object in the
682 // free list. Look through the heap to find a mix of free and uncommitted regions.
683 // If so, try expansion.
684 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
685 if (first != G1_NO_HRM_INDEX) {
686 // We found something. Make sure these regions are committed, i.e. expand
687 // the heap. Alternatively we could do a defragmentation GC.
688 ergo_verbose1(ErgoHeapSizing,
689 "attempt heap expansion",
690 ergo_format_reason("humongous allocation request failed")
691 ergo_format_byte("allocation request"),
692 word_size * HeapWordSize);
693
694 _hrm.expand_at(first, obj_regions);
695 g1_policy()->record_new_heap_size(num_regions());
696
697 #ifdef ASSERT
698 for (uint i = first; i < first + obj_regions; ++i) {
699 HeapRegion* hr = region_at(i);
700 assert(hr->is_free(), "sanity");
701 assert(hr->is_empty(), "sanity");
702 assert(is_on_master_free_list(hr), "sanity");
703 }
704 #endif
705 _hrm.allocate_free_regions_starting_at(first, obj_regions);
706 } else {
707 // Policy: Potentially trigger a defragmentation GC.
708 }
709 }
710
711 HeapWord* result = NULL;
712 if (first != G1_NO_HRM_INDEX) {
713 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
714 word_size, context);
715 assert(result != NULL, "it should always return a valid result");
716
717 // A successful humongous object allocation changes the used space
718 // information of the old generation so we need to recalculate the
719 // sizes and update the jstat counters here.
720 g1mm()->update_sizes();
721 }
722
723 verify_region_sets_optional();
724
725 return result;
726 }
727
728 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
729 assert_heap_not_locked_and_not_at_safepoint();
730 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
731
732 uint dummy_gc_count_before;
733 uint dummy_gclocker_retry_count = 0;
734 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
735 }
736
737 HeapWord*
738 G1CollectedHeap::mem_allocate(size_t word_size,
739 bool* gc_overhead_limit_was_exceeded) {
740 assert_heap_not_locked_and_not_at_safepoint();
741
742 // Loop until the allocation is satisfied, or unsatisfied after GC.
743 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
744 uint gc_count_before;
745
746 HeapWord* result = NULL;
747 if (!is_humongous(word_size)) {
748 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
749 } else {
750 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
751 }
752 if (result != NULL) {
753 return result;
754 }
755
756 // Create the garbage collection operation...
757 VM_G1CollectForAllocation op(gc_count_before, word_size);
758 op.set_allocation_context(AllocationContext::current());
759
760 // ...and get the VM thread to execute it.
761 VMThread::execute(&op);
762
763 if (op.prologue_succeeded() && op.pause_succeeded()) {
764 // If the operation was successful we'll return the result even
765 // if it is NULL. If the allocation attempt failed immediately
766 // after a Full GC, it's unlikely we'll be able to allocate now.
767 HeapWord* result = op.result();
768 if (result != NULL && !is_humongous(word_size)) {
769 // Allocations that take place on VM operations do not do any
770 // card dirtying and we have to do it here. We only have to do
771 // this for non-humongous allocations, though.
772 dirty_young_block(result, word_size);
773 }
774 return result;
775 } else {
776 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
777 return NULL;
778 }
779 assert(op.result() == NULL,
780 "the result should be NULL if the VM op did not succeed");
781 }
782
783 // Give a warning if we seem to be looping forever.
784 if ((QueuedAllocationWarningCount > 0) &&
785 (try_count % QueuedAllocationWarningCount == 0)) {
786 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
787 }
788 }
789
790 ShouldNotReachHere();
791 return NULL;
792 }
793
794 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
795 AllocationContext_t context,
796 uint* gc_count_before_ret,
797 uint* gclocker_retry_count_ret) {
798 // Make sure you read the note in attempt_allocation_humongous().
799
800 assert_heap_not_locked_and_not_at_safepoint();
801 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
802 "be called for humongous allocation requests");
803
804 // We should only get here after the first-level allocation attempt
805 // (attempt_allocation()) failed to allocate.
806
807 // We will loop until a) we manage to successfully perform the
808 // allocation or b) we successfully schedule a collection which
809 // fails to perform the allocation. b) is the only case when we'll
810 // return NULL.
811 HeapWord* result = NULL;
812 for (int try_count = 1; /* we'll return */; try_count += 1) {
813 bool should_try_gc;
814 uint gc_count_before;
815
816 {
817 MutexLockerEx x(Heap_lock);
818 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
819 false /* bot_updates */);
820 if (result != NULL) {
821 return result;
822 }
823
824 // If we reach here, attempt_allocation_locked() above failed to
825 // allocate a new region. So the mutator alloc region should be NULL.
826 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
827
828 if (GC_locker::is_active_and_needs_gc()) {
829 if (g1_policy()->can_expand_young_list()) {
830 // No need for an ergo verbose message here,
831 // can_expand_young_list() does this when it returns true.
832 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
833 false /* bot_updates */);
834 if (result != NULL) {
835 return result;
836 }
837 }
838 should_try_gc = false;
839 } else {
840 // The GCLocker may not be active but the GCLocker initiated
841 // GC may not yet have been performed (GCLocker::needs_gc()
842 // returns true). In this case we do not try this GC and
843 // wait until the GCLocker initiated GC is performed, and
844 // then retry the allocation.
845 if (GC_locker::needs_gc()) {
846 should_try_gc = false;
847 } else {
848 // Read the GC count while still holding the Heap_lock.
849 gc_count_before = total_collections();
850 should_try_gc = true;
851 }
852 }
853 }
854
855 if (should_try_gc) {
856 bool succeeded;
857 result = do_collection_pause(word_size, gc_count_before, &succeeded,
858 GCCause::_g1_inc_collection_pause);
859 if (result != NULL) {
860 assert(succeeded, "only way to get back a non-NULL result");
861 return result;
862 }
863
864 if (succeeded) {
865 // If we get here we successfully scheduled a collection which
866 // failed to allocate. No point in trying to allocate
867 // further. We'll just return NULL.
868 MutexLockerEx x(Heap_lock);
869 *gc_count_before_ret = total_collections();
870 return NULL;
871 }
872 } else {
873 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
874 MutexLockerEx x(Heap_lock);
875 *gc_count_before_ret = total_collections();
876 return NULL;
877 }
878 // The GCLocker is either active or the GCLocker initiated
879 // GC has not yet been performed. Stall until it is and
880 // then retry the allocation.
881 GC_locker::stall_until_clear();
882 (*gclocker_retry_count_ret) += 1;
883 }
884
885 // We can reach here if we were unsuccessful in scheduling a
886 // collection (because another thread beat us to it) or if we were
887 // stalled due to the GC locker. In either can we should retry the
888 // allocation attempt in case another thread successfully
889 // performed a collection and reclaimed enough space. We do the
890 // first attempt (without holding the Heap_lock) here and the
891 // follow-on attempt will be at the start of the next loop
892 // iteration (after taking the Heap_lock).
893 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
894 false /* bot_updates */);
895 if (result != NULL) {
896 return result;
897 }
898
899 // Give a warning if we seem to be looping forever.
900 if ((QueuedAllocationWarningCount > 0) &&
901 (try_count % QueuedAllocationWarningCount == 0)) {
902 warning("G1CollectedHeap::attempt_allocation_slow() "
903 "retries %d times", try_count);
904 }
905 }
906
907 ShouldNotReachHere();
908 return NULL;
909 }
910
911 void G1CollectedHeap::begin_archive_alloc_range() {
912 assert_at_safepoint(true /* should_be_vm_thread */);
913 if (_archive_allocator == NULL) {
914 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
915 }
916 }
917
918 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
919 // Allocations in archive regions cannot be of a size that would be considered
920 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
921 // may be different at archive-restore time.
922 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
923 }
924
925 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
926 assert_at_safepoint(true /* should_be_vm_thread */);
927 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
928 if (is_archive_alloc_too_large(word_size)) {
929 return NULL;
930 }
931 return _archive_allocator->archive_mem_allocate(word_size);
932 }
933
934 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
935 size_t end_alignment_in_bytes) {
936 assert_at_safepoint(true /* should_be_vm_thread */);
937 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
938
939 // Call complete_archive to do the real work, filling in the MemRegion
940 // array with the archive regions.
941 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
942 delete _archive_allocator;
943 _archive_allocator = NULL;
944 }
945
946 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
947 assert(ranges != NULL, "MemRegion array NULL");
948 assert(count != 0, "No MemRegions provided");
949 MemRegion reserved = _hrm.reserved();
950 for (size_t i = 0; i < count; i++) {
951 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
952 return false;
953 }
954 }
955 return true;
956 }
957
958 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
959 assert(ranges != NULL, "MemRegion array NULL");
960 assert(count != 0, "No MemRegions provided");
961 MutexLockerEx x(Heap_lock);
962
963 MemRegion reserved = _hrm.reserved();
964 HeapWord* prev_last_addr = NULL;
965 HeapRegion* prev_last_region = NULL;
966
967 // Temporarily disable pretouching of heap pages. This interface is used
968 // when mmap'ing archived heap data in, so pre-touching is wasted.
969 FlagSetting fs(AlwaysPreTouch, false);
970
971 // Enable archive object checking in G1MarkSweep. We have to let it know
972 // about each archive range, so that objects in those ranges aren't marked.
973 G1MarkSweep::enable_archive_object_check();
974
975 // For each specified MemRegion range, allocate the corresponding G1
976 // regions and mark them as archive regions. We expect the ranges in
977 // ascending starting address order, without overlap.
978 for (size_t i = 0; i < count; i++) {
979 MemRegion curr_range = ranges[i];
980 HeapWord* start_address = curr_range.start();
981 size_t word_size = curr_range.word_size();
982 HeapWord* last_address = curr_range.last();
983 size_t commits = 0;
984
985 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
986 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
987 p2i(start_address), p2i(last_address)));
988 guarantee(start_address > prev_last_addr,
989 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
990 p2i(start_address), p2i(prev_last_addr)));
991 prev_last_addr = last_address;
992
993 // Check for ranges that start in the same G1 region in which the previous
994 // range ended, and adjust the start address so we don't try to allocate
995 // the same region again. If the current range is entirely within that
996 // region, skip it, just adjusting the recorded top.
997 HeapRegion* start_region = _hrm.addr_to_region(start_address);
998 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
999 start_address = start_region->end();
1000 if (start_address > last_address) {
1001 _allocator->increase_used(word_size * HeapWordSize);
1002 start_region->set_top(last_address + 1);
1003 continue;
1004 }
1005 start_region->set_top(start_address);
1006 curr_range = MemRegion(start_address, last_address + 1);
1007 start_region = _hrm.addr_to_region(start_address);
1008 }
1009
1010 // Perform the actual region allocation, exiting if it fails.
1011 // Then note how much new space we have allocated.
1012 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1013 return false;
1014 }
1015 _allocator->increase_used(word_size * HeapWordSize);
1016 if (commits != 0) {
1017 ergo_verbose1(ErgoHeapSizing,
1018 "attempt heap expansion",
1019 ergo_format_reason("allocate archive regions")
1020 ergo_format_byte("total size"),
1021 HeapRegion::GrainWords * HeapWordSize * commits);
1022 }
1023
1024 // Mark each G1 region touched by the range as archive, add it to the old set,
1025 // and set the allocation context and top.
1026 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1027 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1028 prev_last_region = last_region;
1029
1030 while (curr_region != NULL) {
1031 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1032 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1033 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1034 curr_region->set_allocation_context(AllocationContext::system());
1035 curr_region->set_archive();
1036 _old_set.add(curr_region);
1037 if (curr_region != last_region) {
1038 curr_region->set_top(curr_region->end());
1039 curr_region = _hrm.next_region_in_heap(curr_region);
1040 } else {
1041 curr_region->set_top(last_address + 1);
1042 curr_region = NULL;
1043 }
1044 }
1045
1046 // Notify mark-sweep of the archive range.
1047 G1MarkSweep::mark_range_archive(curr_range);
1048 }
1049 return true;
1050 }
1051
1052 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1053 assert(ranges != NULL, "MemRegion array NULL");
1054 assert(count != 0, "No MemRegions provided");
1055 MemRegion reserved = _hrm.reserved();
1056 HeapWord *prev_last_addr = NULL;
1057 HeapRegion* prev_last_region = NULL;
1058
1059 // For each MemRegion, create filler objects, if needed, in the G1 regions
1060 // that contain the address range. The address range actually within the
1061 // MemRegion will not be modified. That is assumed to have been initialized
1062 // elsewhere, probably via an mmap of archived heap data.
1063 MutexLockerEx x(Heap_lock);
1064 for (size_t i = 0; i < count; i++) {
1065 HeapWord* start_address = ranges[i].start();
1066 HeapWord* last_address = ranges[i].last();
1067
1068 assert(reserved.contains(start_address) && reserved.contains(last_address),
1069 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1070 p2i(start_address), p2i(last_address)));
1071 assert(start_address > prev_last_addr,
1072 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1073 p2i(start_address), p2i(prev_last_addr)));
1074
1075 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1076 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1077 HeapWord* bottom_address = start_region->bottom();
1078
1079 // Check for a range beginning in the same region in which the
1080 // previous one ended.
1081 if (start_region == prev_last_region) {
1082 bottom_address = prev_last_addr + 1;
1083 }
1084
1085 // Verify that the regions were all marked as archive regions by
1086 // alloc_archive_regions.
1087 HeapRegion* curr_region = start_region;
1088 while (curr_region != NULL) {
1089 guarantee(curr_region->is_archive(),
1090 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1091 if (curr_region != last_region) {
1092 curr_region = _hrm.next_region_in_heap(curr_region);
1093 } else {
1094 curr_region = NULL;
1095 }
1096 }
1097
1098 prev_last_addr = last_address;
1099 prev_last_region = last_region;
1100
1101 // Fill the memory below the allocated range with dummy object(s),
1102 // if the region bottom does not match the range start, or if the previous
1103 // range ended within the same G1 region, and there is a gap.
1104 if (start_address != bottom_address) {
1105 size_t fill_size = pointer_delta(start_address, bottom_address);
1106 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1107 _allocator->increase_used(fill_size * HeapWordSize);
1108 }
1109 }
1110 }
1111
1112 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1113 uint* gc_count_before_ret,
1114 uint* gclocker_retry_count_ret) {
1115 // The structure of this method has a lot of similarities to
1116 // attempt_allocation_slow(). The reason these two were not merged
1117 // into a single one is that such a method would require several "if
1118 // allocation is not humongous do this, otherwise do that"
1119 // conditional paths which would obscure its flow. In fact, an early
1120 // version of this code did use a unified method which was harder to
1121 // follow and, as a result, it had subtle bugs that were hard to
1122 // track down. So keeping these two methods separate allows each to
1123 // be more readable. It will be good to keep these two in sync as
1124 // much as possible.
1125
1126 assert_heap_not_locked_and_not_at_safepoint();
1127 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1128 "should only be called for humongous allocations");
1129
1130 // Humongous objects can exhaust the heap quickly, so we should check if we
1131 // need to start a marking cycle at each humongous object allocation. We do
1132 // the check before we do the actual allocation. The reason for doing it
1133 // before the allocation is that we avoid having to keep track of the newly
1134 // allocated memory while we do a GC.
1135 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1136 word_size)) {
1137 collect(GCCause::_g1_humongous_allocation);
1138 }
1139
1140 // We will loop until a) we manage to successfully perform the
1141 // allocation or b) we successfully schedule a collection which
1142 // fails to perform the allocation. b) is the only case when we'll
1143 // return NULL.
1144 HeapWord* result = NULL;
1145 for (int try_count = 1; /* we'll return */; try_count += 1) {
1146 bool should_try_gc;
1147 uint gc_count_before;
1148
1149 {
1150 MutexLockerEx x(Heap_lock);
1151
1152 // Given that humongous objects are not allocated in young
1153 // regions, we'll first try to do the allocation without doing a
1154 // collection hoping that there's enough space in the heap.
1155 result = humongous_obj_allocate(word_size, AllocationContext::current());
1156 if (result != NULL) {
1157 return result;
1158 }
1159
1160 if (GC_locker::is_active_and_needs_gc()) {
1161 should_try_gc = false;
1162 } else {
1163 // The GCLocker may not be active but the GCLocker initiated
1164 // GC may not yet have been performed (GCLocker::needs_gc()
1165 // returns true). In this case we do not try this GC and
1166 // wait until the GCLocker initiated GC is performed, and
1167 // then retry the allocation.
1168 if (GC_locker::needs_gc()) {
1169 should_try_gc = false;
1170 } else {
1171 // Read the GC count while still holding the Heap_lock.
1172 gc_count_before = total_collections();
1173 should_try_gc = true;
1174 }
1175 }
1176 }
1177
1178 if (should_try_gc) {
1179 // If we failed to allocate the humongous object, we should try to
1180 // do a collection pause (if we're allowed) in case it reclaims
1181 // enough space for the allocation to succeed after the pause.
1182
1183 bool succeeded;
1184 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1185 GCCause::_g1_humongous_allocation);
1186 if (result != NULL) {
1187 assert(succeeded, "only way to get back a non-NULL result");
1188 return result;
1189 }
1190
1191 if (succeeded) {
1192 // If we get here we successfully scheduled a collection which
1193 // failed to allocate. No point in trying to allocate
1194 // further. We'll just return NULL.
1195 MutexLockerEx x(Heap_lock);
1196 *gc_count_before_ret = total_collections();
1197 return NULL;
1198 }
1199 } else {
1200 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1201 MutexLockerEx x(Heap_lock);
1202 *gc_count_before_ret = total_collections();
1203 return NULL;
1204 }
1205 // The GCLocker is either active or the GCLocker initiated
1206 // GC has not yet been performed. Stall until it is and
1207 // then retry the allocation.
1208 GC_locker::stall_until_clear();
1209 (*gclocker_retry_count_ret) += 1;
1210 }
1211
1212 // We can reach here if we were unsuccessful in scheduling a
1213 // collection (because another thread beat us to it) or if we were
1214 // stalled due to the GC locker. In either can we should retry the
1215 // allocation attempt in case another thread successfully
1216 // performed a collection and reclaimed enough space. Give a
1217 // warning if we seem to be looping forever.
1218
1219 if ((QueuedAllocationWarningCount > 0) &&
1220 (try_count % QueuedAllocationWarningCount == 0)) {
1221 warning("G1CollectedHeap::attempt_allocation_humongous() "
1222 "retries %d times", try_count);
1223 }
1224 }
1225
1226 ShouldNotReachHere();
1227 return NULL;
1228 }
1229
1230 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1231 AllocationContext_t context,
1232 bool expect_null_mutator_alloc_region) {
1233 assert_at_safepoint(true /* should_be_vm_thread */);
1234 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1235 !expect_null_mutator_alloc_region,
1236 "the current alloc region was unexpectedly found to be non-NULL");
1237
1238 if (!is_humongous(word_size)) {
1239 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1240 false /* bot_updates */);
1241 } else {
1242 HeapWord* result = humongous_obj_allocate(word_size, context);
1243 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1244 collector_state()->set_initiate_conc_mark_if_possible(true);
1245 }
1246 return result;
1247 }
1248
1249 ShouldNotReachHere();
1250 }
1251
1252 class PostMCRemSetClearClosure: public HeapRegionClosure {
1253 G1CollectedHeap* _g1h;
1254 ModRefBarrierSet* _mr_bs;
1255 public:
1256 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1257 _g1h(g1h), _mr_bs(mr_bs) {}
1258
1259 bool doHeapRegion(HeapRegion* r) {
1260 HeapRegionRemSet* hrrs = r->rem_set();
1261
1262 if (r->is_continues_humongous()) {
1263 // We'll assert that the strong code root list and RSet is empty
1264 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1265 assert(hrrs->occupied() == 0, "RSet should be empty");
1266 return false;
1267 }
1268
1269 _g1h->reset_gc_time_stamps(r);
1270 hrrs->clear();
1271 // You might think here that we could clear just the cards
1272 // corresponding to the used region. But no: if we leave a dirty card
1273 // in a region we might allocate into, then it would prevent that card
1274 // from being enqueued, and cause it to be missed.
1275 // Re: the performance cost: we shouldn't be doing full GC anyway!
1276 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1277
1278 return false;
1279 }
1280 };
1281
1282 void G1CollectedHeap::clear_rsets_post_compaction() {
1283 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1284 heap_region_iterate(&rs_clear);
1285 }
1286
1287 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1288 G1CollectedHeap* _g1h;
1289 UpdateRSOopClosure _cl;
1290 public:
1291 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1292 _cl(g1->g1_rem_set(), worker_i),
1293 _g1h(g1)
1294 { }
1295
1296 bool doHeapRegion(HeapRegion* r) {
1297 if (!r->is_continues_humongous()) {
1298 _cl.set_from(r);
1299 r->oop_iterate(&_cl);
1300 }
1301 return false;
1302 }
1303 };
1304
1305 class ParRebuildRSTask: public AbstractGangTask {
1306 G1CollectedHeap* _g1;
1307 HeapRegionClaimer _hrclaimer;
1308
1309 public:
1310 ParRebuildRSTask(G1CollectedHeap* g1) :
1311 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1312
1313 void work(uint worker_id) {
1314 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1315 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1316 }
1317 };
1318
1319 class PostCompactionPrinterClosure: public HeapRegionClosure {
1320 private:
1321 G1HRPrinter* _hr_printer;
1322 public:
1323 bool doHeapRegion(HeapRegion* hr) {
1324 assert(!hr->is_young(), "not expecting to find young regions");
1325 if (hr->is_free()) {
1326 // We only generate output for non-empty regions.
1327 } else if (hr->is_starts_humongous()) {
1328 if (hr->region_num() == 1) {
1329 // single humongous region
1330 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1331 } else {
1332 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1333 }
1334 } else if (hr->is_continues_humongous()) {
1335 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1336 } else if (hr->is_archive()) {
1337 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1338 } else if (hr->is_old()) {
1339 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1340 } else {
1341 ShouldNotReachHere();
1342 }
1343 return false;
1344 }
1345
1346 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1347 : _hr_printer(hr_printer) { }
1348 };
1349
1350 void G1CollectedHeap::print_hrm_post_compaction() {
1351 PostCompactionPrinterClosure cl(hr_printer());
1352 heap_region_iterate(&cl);
1353 }
1354
1355 bool G1CollectedHeap::do_collection(bool explicit_gc,
1356 bool clear_all_soft_refs,
1357 size_t word_size) {
1358 assert_at_safepoint(true /* should_be_vm_thread */);
1359
1360 if (GC_locker::check_active_before_gc()) {
1361 return false;
1362 }
1363
1364 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1365 gc_timer->register_gc_start();
1366
1367 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1368 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1369
1370 SvcGCMarker sgcm(SvcGCMarker::FULL);
1371 ResourceMark rm;
1372
1373 G1Log::update_level();
1374 print_heap_before_gc();
1375 trace_heap_before_gc(gc_tracer);
1376
1377 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1378
1379 verify_region_sets_optional();
1380
1381 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1382 collector_policy()->should_clear_all_soft_refs();
1383
1384 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1385
1386 {
1387 IsGCActiveMark x;
1388
1389 // Timing
1390 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1391 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1392
1393 {
1394 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1395 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1396 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1397
1398 g1_policy()->record_full_collection_start();
1399
1400 // Note: When we have a more flexible GC logging framework that
1401 // allows us to add optional attributes to a GC log record we
1402 // could consider timing and reporting how long we wait in the
1403 // following two methods.
1404 wait_while_free_regions_coming();
1405 // If we start the compaction before the CM threads finish
1406 // scanning the root regions we might trip them over as we'll
1407 // be moving objects / updating references. So let's wait until
1408 // they are done. By telling them to abort, they should complete
1409 // early.
1410 _cm->root_regions()->abort();
1411 _cm->root_regions()->wait_until_scan_finished();
1412 append_secondary_free_list_if_not_empty_with_lock();
1413
1414 gc_prologue(true);
1415 increment_total_collections(true /* full gc */);
1416 increment_old_marking_cycles_started();
1417
1418 assert(used() == recalculate_used(), "Should be equal");
1419
1420 verify_before_gc();
1421
1422 check_bitmaps("Full GC Start");
1423 pre_full_gc_dump(gc_timer);
1424
1425 COMPILER2_PRESENT(DerivedPointerTable::clear());
1426
1427 // Disable discovery and empty the discovered lists
1428 // for the CM ref processor.
1429 ref_processor_cm()->disable_discovery();
1430 ref_processor_cm()->abandon_partial_discovery();
1431 ref_processor_cm()->verify_no_references_recorded();
1432
1433 // Abandon current iterations of concurrent marking and concurrent
1434 // refinement, if any are in progress. We have to do this before
1435 // wait_until_scan_finished() below.
1436 concurrent_mark()->abort();
1437
1438 // Make sure we'll choose a new allocation region afterwards.
1439 _allocator->release_mutator_alloc_region();
1440 _allocator->abandon_gc_alloc_regions();
1441 g1_rem_set()->cleanupHRRS();
1442
1443 // We should call this after we retire any currently active alloc
1444 // regions so that all the ALLOC / RETIRE events are generated
1445 // before the start GC event.
1446 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1447
1448 // We may have added regions to the current incremental collection
1449 // set between the last GC or pause and now. We need to clear the
1450 // incremental collection set and then start rebuilding it afresh
1451 // after this full GC.
1452 abandon_collection_set(g1_policy()->inc_cset_head());
1453 g1_policy()->clear_incremental_cset();
1454 g1_policy()->stop_incremental_cset_building();
1455
1456 tear_down_region_sets(false /* free_list_only */);
1457 collector_state()->set_gcs_are_young(true);
1458
1459 // See the comments in g1CollectedHeap.hpp and
1460 // G1CollectedHeap::ref_processing_init() about
1461 // how reference processing currently works in G1.
1462
1463 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1464 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1465
1466 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1467 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1468
1469 ref_processor_stw()->enable_discovery();
1470 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1471
1472 // Do collection work
1473 {
1474 HandleMark hm; // Discard invalid handles created during gc
1475 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1476 }
1477
1478 assert(num_free_regions() == 0, "we should not have added any free regions");
1479 rebuild_region_sets(false /* free_list_only */);
1480
1481 // Enqueue any discovered reference objects that have
1482 // not been removed from the discovered lists.
1483 ref_processor_stw()->enqueue_discovered_references();
1484
1485 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1486
1487 MemoryService::track_memory_usage();
1488
1489 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1490 ref_processor_stw()->verify_no_references_recorded();
1491
1492 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1493 ClassLoaderDataGraph::purge();
1494 MetaspaceAux::verify_metrics();
1495
1496 // Note: since we've just done a full GC, concurrent
1497 // marking is no longer active. Therefore we need not
1498 // re-enable reference discovery for the CM ref processor.
1499 // That will be done at the start of the next marking cycle.
1500 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1501 ref_processor_cm()->verify_no_references_recorded();
1502
1503 reset_gc_time_stamp();
1504 // Since everything potentially moved, we will clear all remembered
1505 // sets, and clear all cards. Later we will rebuild remembered
1506 // sets. We will also reset the GC time stamps of the regions.
1507 clear_rsets_post_compaction();
1508 check_gc_time_stamps();
1509
1510 // Resize the heap if necessary.
1511 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1512
1513 if (_hr_printer.is_active()) {
1514 // We should do this after we potentially resize the heap so
1515 // that all the COMMIT / UNCOMMIT events are generated before
1516 // the end GC event.
1517
1518 print_hrm_post_compaction();
1519 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1520 }
1521
1522 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1523 if (hot_card_cache->use_cache()) {
1524 hot_card_cache->reset_card_counts();
1525 hot_card_cache->reset_hot_cache();
1526 }
1527
1528 // Rebuild remembered sets of all regions.
1529 uint n_workers =
1530 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1531 workers()->active_workers(),
1532 Threads::number_of_non_daemon_threads());
1533 workers()->set_active_workers(n_workers);
1534
1535 ParRebuildRSTask rebuild_rs_task(this);
1536 workers()->run_task(&rebuild_rs_task);
1537
1538 // Rebuild the strong code root lists for each region
1539 rebuild_strong_code_roots();
1540
1541 if (true) { // FIXME
1542 MetaspaceGC::compute_new_size();
1543 }
1544
1545 #ifdef TRACESPINNING
1546 ParallelTaskTerminator::print_termination_counts();
1547 #endif
1548
1549 // Discard all rset updates
1550 JavaThread::dirty_card_queue_set().abandon_logs();
1551 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1552
1553 _young_list->reset_sampled_info();
1554 // At this point there should be no regions in the
1555 // entire heap tagged as young.
1556 assert(check_young_list_empty(true /* check_heap */),
1557 "young list should be empty at this point");
1558
1559 // Update the number of full collections that have been completed.
1560 increment_old_marking_cycles_completed(false /* concurrent */);
1561
1562 _hrm.verify_optional();
1563 verify_region_sets_optional();
1564
1565 verify_after_gc();
1566
1567 // Clear the previous marking bitmap, if needed for bitmap verification.
1568 // Note we cannot do this when we clear the next marking bitmap in
1569 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1570 // objects marked during a full GC against the previous bitmap.
1571 // But we need to clear it before calling check_bitmaps below since
1572 // the full GC has compacted objects and updated TAMS but not updated
1573 // the prev bitmap.
1574 if (G1VerifyBitmaps) {
1575 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1576 }
1577 check_bitmaps("Full GC End");
1578
1579 // Start a new incremental collection set for the next pause
1580 assert(g1_policy()->collection_set() == NULL, "must be");
1581 g1_policy()->start_incremental_cset_building();
1582
1583 clear_cset_fast_test();
1584
1585 _allocator->init_mutator_alloc_region();
1586
1587 g1_policy()->record_full_collection_end();
1588
1589 if (G1Log::fine()) {
1590 g1_policy()->print_heap_transition();
1591 }
1592
1593 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1594 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1595 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1596 // before any GC notifications are raised.
1597 g1mm()->update_sizes();
1598
1599 gc_epilogue(true);
1600 }
1601
1602 if (G1Log::finer()) {
1603 g1_policy()->print_detailed_heap_transition(true /* full */);
1604 }
1605
1606 print_heap_after_gc();
1607 trace_heap_after_gc(gc_tracer);
1608
1609 post_full_gc_dump(gc_timer);
1610
1611 gc_timer->register_gc_end();
1612 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1613 }
1614
1615 return true;
1616 }
1617
1618 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1619 // do_collection() will return whether it succeeded in performing
1620 // the GC. Currently, there is no facility on the
1621 // do_full_collection() API to notify the caller than the collection
1622 // did not succeed (e.g., because it was locked out by the GC
1623 // locker). So, right now, we'll ignore the return value.
1624 bool dummy = do_collection(true, /* explicit_gc */
1625 clear_all_soft_refs,
1626 0 /* word_size */);
1627 }
1628
1629 // This code is mostly copied from TenuredGeneration.
1630 void
1631 G1CollectedHeap::
1632 resize_if_necessary_after_full_collection(size_t word_size) {
1633 // Include the current allocation, if any, and bytes that will be
1634 // pre-allocated to support collections, as "used".
1635 const size_t used_after_gc = used();
1636 const size_t capacity_after_gc = capacity();
1637 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1638
1639 // This is enforced in arguments.cpp.
1640 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1641 "otherwise the code below doesn't make sense");
1642
1643 // We don't have floating point command-line arguments
1644 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1645 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1646 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1647 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1648
1649 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1650 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1651
1652 // We have to be careful here as these two calculations can overflow
1653 // 32-bit size_t's.
1654 double used_after_gc_d = (double) used_after_gc;
1655 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1656 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1657
1658 // Let's make sure that they are both under the max heap size, which
1659 // by default will make them fit into a size_t.
1660 double desired_capacity_upper_bound = (double) max_heap_size;
1661 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1662 desired_capacity_upper_bound);
1663 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1664 desired_capacity_upper_bound);
1665
1666 // We can now safely turn them into size_t's.
1667 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1668 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1669
1670 // This assert only makes sense here, before we adjust them
1671 // with respect to the min and max heap size.
1672 assert(minimum_desired_capacity <= maximum_desired_capacity,
1673 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1674 "maximum_desired_capacity = " SIZE_FORMAT,
1675 minimum_desired_capacity, maximum_desired_capacity));
1676
1677 // Should not be greater than the heap max size. No need to adjust
1678 // it with respect to the heap min size as it's a lower bound (i.e.,
1679 // we'll try to make the capacity larger than it, not smaller).
1680 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1681 // Should not be less than the heap min size. No need to adjust it
1682 // with respect to the heap max size as it's an upper bound (i.e.,
1683 // we'll try to make the capacity smaller than it, not greater).
1684 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1685
1686 if (capacity_after_gc < minimum_desired_capacity) {
1687 // Don't expand unless it's significant
1688 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1689 ergo_verbose4(ErgoHeapSizing,
1690 "attempt heap expansion",
1691 ergo_format_reason("capacity lower than "
1692 "min desired capacity after Full GC")
1693 ergo_format_byte("capacity")
1694 ergo_format_byte("occupancy")
1695 ergo_format_byte_perc("min desired capacity"),
1696 capacity_after_gc, used_after_gc,
1697 minimum_desired_capacity, (double) MinHeapFreeRatio);
1698 expand(expand_bytes);
1699
1700 // No expansion, now see if we want to shrink
1701 } else if (capacity_after_gc > maximum_desired_capacity) {
1702 // Capacity too large, compute shrinking size
1703 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1704 ergo_verbose4(ErgoHeapSizing,
1705 "attempt heap shrinking",
1706 ergo_format_reason("capacity higher than "
1707 "max desired capacity after Full GC")
1708 ergo_format_byte("capacity")
1709 ergo_format_byte("occupancy")
1710 ergo_format_byte_perc("max desired capacity"),
1711 capacity_after_gc, used_after_gc,
1712 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1713 shrink(shrink_bytes);
1714 }
1715 }
1716
1717
1718 HeapWord*
1719 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1720 AllocationContext_t context,
1721 bool* succeeded) {
1722 assert_at_safepoint(true /* should_be_vm_thread */);
1723
1724 *succeeded = true;
1725 // Let's attempt the allocation first.
1726 HeapWord* result =
1727 attempt_allocation_at_safepoint(word_size,
1728 context,
1729 false /* expect_null_mutator_alloc_region */);
1730 if (result != NULL) {
1731 assert(*succeeded, "sanity");
1732 return result;
1733 }
1734
1735 // In a G1 heap, we're supposed to keep allocation from failing by
1736 // incremental pauses. Therefore, at least for now, we'll favor
1737 // expansion over collection. (This might change in the future if we can
1738 // do something smarter than full collection to satisfy a failed alloc.)
1739 result = expand_and_allocate(word_size, context);
1740 if (result != NULL) {
1741 assert(*succeeded, "sanity");
1742 return result;
1743 }
1744
1745 // Expansion didn't work, we'll try to do a Full GC.
1746 bool gc_succeeded = do_collection(false, /* explicit_gc */
1747 false, /* clear_all_soft_refs */
1748 word_size);
1749 if (!gc_succeeded) {
1750 *succeeded = false;
1751 return NULL;
1752 }
1753
1754 // Retry the allocation
1755 result = attempt_allocation_at_safepoint(word_size,
1756 context,
1757 true /* expect_null_mutator_alloc_region */);
1758 if (result != NULL) {
1759 assert(*succeeded, "sanity");
1760 return result;
1761 }
1762
1763 // Then, try a Full GC that will collect all soft references.
1764 gc_succeeded = do_collection(false, /* explicit_gc */
1765 true, /* clear_all_soft_refs */
1766 word_size);
1767 if (!gc_succeeded) {
1768 *succeeded = false;
1769 return NULL;
1770 }
1771
1772 // Retry the allocation once more
1773 result = attempt_allocation_at_safepoint(word_size,
1774 context,
1775 true /* expect_null_mutator_alloc_region */);
1776 if (result != NULL) {
1777 assert(*succeeded, "sanity");
1778 return result;
1779 }
1780
1781 assert(!collector_policy()->should_clear_all_soft_refs(),
1782 "Flag should have been handled and cleared prior to this point");
1783
1784 // What else? We might try synchronous finalization later. If the total
1785 // space available is large enough for the allocation, then a more
1786 // complete compaction phase than we've tried so far might be
1787 // appropriate.
1788 assert(*succeeded, "sanity");
1789 return NULL;
1790 }
1791
1792 // Attempting to expand the heap sufficiently
1793 // to support an allocation of the given "word_size". If
1794 // successful, perform the allocation and return the address of the
1795 // allocated block, or else "NULL".
1796
1797 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1798 assert_at_safepoint(true /* should_be_vm_thread */);
1799
1800 verify_region_sets_optional();
1801
1802 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1803 ergo_verbose1(ErgoHeapSizing,
1804 "attempt heap expansion",
1805 ergo_format_reason("allocation request failed")
1806 ergo_format_byte("allocation request"),
1807 word_size * HeapWordSize);
1808 if (expand(expand_bytes)) {
1809 _hrm.verify_optional();
1810 verify_region_sets_optional();
1811 return attempt_allocation_at_safepoint(word_size,
1812 context,
1813 false /* expect_null_mutator_alloc_region */);
1814 }
1815 return NULL;
1816 }
1817
1818 bool G1CollectedHeap::expand(size_t expand_bytes) {
1819 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1820 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1821 HeapRegion::GrainBytes);
1822 ergo_verbose2(ErgoHeapSizing,
1823 "expand the heap",
1824 ergo_format_byte("requested expansion amount")
1825 ergo_format_byte("attempted expansion amount"),
1826 expand_bytes, aligned_expand_bytes);
1827
1828 if (is_maximal_no_gc()) {
1829 ergo_verbose0(ErgoHeapSizing,
1830 "did not expand the heap",
1831 ergo_format_reason("heap already fully expanded"));
1832 return false;
1833 }
1834
1835 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1836 assert(regions_to_expand > 0, "Must expand by at least one region");
1837
1838 uint expanded_by = _hrm.expand_by(regions_to_expand);
1839
1840 if (expanded_by > 0) {
1841 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1842 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1843 g1_policy()->record_new_heap_size(num_regions());
1844 } else {
1845 ergo_verbose0(ErgoHeapSizing,
1846 "did not expand the heap",
1847 ergo_format_reason("heap expansion operation failed"));
1848 // The expansion of the virtual storage space was unsuccessful.
1849 // Let's see if it was because we ran out of swap.
1850 if (G1ExitOnExpansionFailure &&
1851 _hrm.available() >= regions_to_expand) {
1852 // We had head room...
1853 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1854 }
1855 }
1856 return regions_to_expand > 0;
1857 }
1858
1859 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1860 size_t aligned_shrink_bytes =
1861 ReservedSpace::page_align_size_down(shrink_bytes);
1862 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863 HeapRegion::GrainBytes);
1864 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865
1866 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1867 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1868
1869 ergo_verbose3(ErgoHeapSizing,
1870 "shrink the heap",
1871 ergo_format_byte("requested shrinking amount")
1872 ergo_format_byte("aligned shrinking amount")
1873 ergo_format_byte("attempted shrinking amount"),
1874 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1875 if (num_regions_removed > 0) {
1876 g1_policy()->record_new_heap_size(num_regions());
1877 } else {
1878 ergo_verbose0(ErgoHeapSizing,
1879 "did not shrink the heap",
1880 ergo_format_reason("heap shrinking operation failed"));
1881 }
1882 }
1883
1884 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1885 verify_region_sets_optional();
1886
1887 // We should only reach here at the end of a Full GC which means we
1888 // should not not be holding to any GC alloc regions. The method
1889 // below will make sure of that and do any remaining clean up.
1890 _allocator->abandon_gc_alloc_regions();
1891
1892 // Instead of tearing down / rebuilding the free lists here, we
1893 // could instead use the remove_all_pending() method on free_list to
1894 // remove only the ones that we need to remove.
1895 tear_down_region_sets(true /* free_list_only */);
1896 shrink_helper(shrink_bytes);
1897 rebuild_region_sets(true /* free_list_only */);
1898
1899 _hrm.verify_optional();
1900 verify_region_sets_optional();
1901 }
1902
1903 // Public methods.
1904
1905 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1906 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1907 #endif // _MSC_VER
1908
1909
1910 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1911 CollectedHeap(),
1912 _g1_policy(policy_),
1913 _dirty_card_queue_set(false),
1914 _into_cset_dirty_card_queue_set(false),
1915 _is_alive_closure_cm(this),
1916 _is_alive_closure_stw(this),
1917 _ref_processor_cm(NULL),
1918 _ref_processor_stw(NULL),
1919 _bot_shared(NULL),
1920 _cg1r(NULL),
1921 _g1mm(NULL),
1922 _refine_cte_cl(NULL),
1923 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1924 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1925 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1926 _humongous_reclaim_candidates(),
1927 _has_humongous_reclaim_candidates(false),
1928 _archive_allocator(NULL),
1929 _free_regions_coming(false),
1930 _young_list(new YoungList(this)),
1931 _gc_time_stamp(0),
1932 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1933 _old_plab_stats(OldPLABSize, PLABWeight),
1934 _expand_heap_after_alloc_failure(true),
1935 _surviving_young_words(NULL),
1936 _old_marking_cycles_started(0),
1937 _old_marking_cycles_completed(0),
1938 _heap_summary_sent(false),
1939 _in_cset_fast_test(),
1940 _dirty_cards_region_list(NULL),
1941 _worker_cset_start_region(NULL),
1942 _worker_cset_start_region_time_stamp(NULL),
1943 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1944 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1945 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1946 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1947
1948 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1949 /* are_GC_task_threads */true,
1950 /* are_ConcurrentGC_threads */false);
1951 _workers->initialize_workers();
1952
1953 _allocator = G1Allocator::create_allocator(this);
1954 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1955
1956 // Override the default _filler_array_max_size so that no humongous filler
1957 // objects are created.
1958 _filler_array_max_size = _humongous_object_threshold_in_words;
1959
1960 uint n_queues = ParallelGCThreads;
1961 _task_queues = new RefToScanQueueSet(n_queues);
1962
1963 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1964 assert(n_rem_sets > 0, "Invariant.");
1965
1966 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1967 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1968 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1969
1970 for (uint i = 0; i < n_queues; i++) {
1971 RefToScanQueue* q = new RefToScanQueue();
1972 q->initialize();
1973 _task_queues->register_queue(i, q);
1974 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1975 }
1976 clear_cset_start_regions();
1977
1978 // Initialize the G1EvacuationFailureALot counters and flags.
1979 NOT_PRODUCT(reset_evacuation_should_fail();)
1980
1981 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1982 }
1983
1984 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1985 size_t size,
1986 size_t translation_factor) {
1987 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1988 // Allocate a new reserved space, preferring to use large pages.
1989 ReservedSpace rs(size, preferred_page_size);
1990 G1RegionToSpaceMapper* result =
1991 G1RegionToSpaceMapper::create_mapper(rs,
1992 size,
1993 rs.alignment(),
1994 HeapRegion::GrainBytes,
1995 translation_factor,
1996 mtGC);
1997 if (TracePageSizes) {
1998 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1999 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2000 }
2001 return result;
2002 }
2003
2004 jint G1CollectedHeap::initialize() {
2005 CollectedHeap::pre_initialize();
2006 os::enable_vtime();
2007
2008 G1Log::init();
2009
2010 // Necessary to satisfy locking discipline assertions.
2011
2012 MutexLocker x(Heap_lock);
2013
2014 // We have to initialize the printer before committing the heap, as
2015 // it will be used then.
2016 _hr_printer.set_active(G1PrintHeapRegions);
2017
2018 // While there are no constraints in the GC code that HeapWordSize
2019 // be any particular value, there are multiple other areas in the
2020 // system which believe this to be true (e.g. oop->object_size in some
2021 // cases incorrectly returns the size in wordSize units rather than
2022 // HeapWordSize).
2023 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2024
2025 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2026 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2027 size_t heap_alignment = collector_policy()->heap_alignment();
2028
2029 // Ensure that the sizes are properly aligned.
2030 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2031 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2032 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2033
2034 _refine_cte_cl = new RefineCardTableEntryClosure();
2035
2036 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2037
2038 // Reserve the maximum.
2039
2040 // When compressed oops are enabled, the preferred heap base
2041 // is calculated by subtracting the requested size from the
2042 // 32Gb boundary and using the result as the base address for
2043 // heap reservation. If the requested size is not aligned to
2044 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2045 // into the ReservedHeapSpace constructor) then the actual
2046 // base of the reserved heap may end up differing from the
2047 // address that was requested (i.e. the preferred heap base).
2048 // If this happens then we could end up using a non-optimal
2049 // compressed oops mode.
2050
2051 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2052 heap_alignment);
2053
2054 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2055
2056 // Create the barrier set for the entire reserved region.
2057 G1SATBCardTableLoggingModRefBS* bs
2058 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2059 bs->initialize();
2060 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2061 set_barrier_set(bs);
2062
2063 // Also create a G1 rem set.
2064 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2065
2066 // Carve out the G1 part of the heap.
2067
2068 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2069 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2070 G1RegionToSpaceMapper* heap_storage =
2071 G1RegionToSpaceMapper::create_mapper(g1_rs,
2072 g1_rs.size(),
2073 page_size,
2074 HeapRegion::GrainBytes,
2075 1,
2076 mtJavaHeap);
2077 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2078 max_byte_size, page_size,
2079 heap_rs.base(),
2080 heap_rs.size());
2081 heap_storage->set_mapping_changed_listener(&_listener);
2082
2083 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2084 G1RegionToSpaceMapper* bot_storage =
2085 create_aux_memory_mapper("Block offset table",
2086 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2087 G1BlockOffsetSharedArray::heap_map_factor());
2088
2089 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2090 G1RegionToSpaceMapper* cardtable_storage =
2091 create_aux_memory_mapper("Card table",
2092 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2093 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2094
2095 G1RegionToSpaceMapper* card_counts_storage =
2096 create_aux_memory_mapper("Card counts table",
2097 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2098 G1CardCounts::heap_map_factor());
2099
2100 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2101 G1RegionToSpaceMapper* prev_bitmap_storage =
2102 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2103 G1RegionToSpaceMapper* next_bitmap_storage =
2104 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2105
2106 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2107 g1_barrier_set()->initialize(cardtable_storage);
2108 // Do later initialization work for concurrent refinement.
2109 _cg1r->init(card_counts_storage);
2110
2111 // 6843694 - ensure that the maximum region index can fit
2112 // in the remembered set structures.
2113 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2114 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2115
2116 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2117 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2118 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2119 "too many cards per region");
2120
2121 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2122
2123 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2124
2125 {
2126 HeapWord* start = _hrm.reserved().start();
2127 HeapWord* end = _hrm.reserved().end();
2128 size_t granularity = HeapRegion::GrainBytes;
2129
2130 _in_cset_fast_test.initialize(start, end, granularity);
2131 _humongous_reclaim_candidates.initialize(start, end, granularity);
2132 }
2133
2134 // Create the ConcurrentMark data structure and thread.
2135 // (Must do this late, so that "max_regions" is defined.)
2136 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2137 if (_cm == NULL || !_cm->completed_initialization()) {
2138 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2139 return JNI_ENOMEM;
2140 }
2141 _cmThread = _cm->cmThread();
2142
2143 // Initialize the from_card cache structure of HeapRegionRemSet.
2144 HeapRegionRemSet::init_heap(max_regions());
2145
2146 // Now expand into the initial heap size.
2147 if (!expand(init_byte_size)) {
2148 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2149 return JNI_ENOMEM;
2150 }
2151
2152 // Perform any initialization actions delegated to the policy.
2153 g1_policy()->init();
2154
2155 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2156 SATB_Q_FL_lock,
2157 G1SATBProcessCompletedThreshold,
2158 Shared_SATB_Q_lock);
2159
2160 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2161 DirtyCardQ_CBL_mon,
2162 DirtyCardQ_FL_lock,
2163 concurrent_g1_refine()->yellow_zone(),
2164 concurrent_g1_refine()->red_zone(),
2165 Shared_DirtyCardQ_lock);
2166
2167 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2168 DirtyCardQ_CBL_mon,
2169 DirtyCardQ_FL_lock,
2170 -1, // never trigger processing
2171 -1, // no limit on length
2172 Shared_DirtyCardQ_lock,
2173 &JavaThread::dirty_card_queue_set());
2174
2175 // Initialize the card queue set used to hold cards containing
2176 // references into the collection set.
2177 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2178 DirtyCardQ_CBL_mon,
2179 DirtyCardQ_FL_lock,
2180 -1, // never trigger processing
2181 -1, // no limit on length
2182 Shared_DirtyCardQ_lock,
2183 &JavaThread::dirty_card_queue_set());
2184
2185 // Here we allocate the dummy HeapRegion that is required by the
2186 // G1AllocRegion class.
2187 HeapRegion* dummy_region = _hrm.get_dummy_region();
2188
2189 // We'll re-use the same region whether the alloc region will
2190 // require BOT updates or not and, if it doesn't, then a non-young
2191 // region will complain that it cannot support allocations without
2192 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2193 dummy_region->set_eden();
2194 // Make sure it's full.
2195 dummy_region->set_top(dummy_region->end());
2196 G1AllocRegion::setup(this, dummy_region);
2197
2198 _allocator->init_mutator_alloc_region();
2199
2200 // Do create of the monitoring and management support so that
2201 // values in the heap have been properly initialized.
2202 _g1mm = new G1MonitoringSupport(this);
2203
2204 G1StringDedup::initialize();
2205
2206 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2207 for (uint i = 0; i < ParallelGCThreads; i++) {
2208 new (&_preserved_objs[i]) OopAndMarkOopStack();
2209 }
2210
2211 return JNI_OK;
2212 }
2213
2214 void G1CollectedHeap::stop() {
2215 // Stop all concurrent threads. We do this to make sure these threads
2216 // do not continue to execute and access resources (e.g. gclog_or_tty)
2217 // that are destroyed during shutdown.
2218 _cg1r->stop();
2219 _cmThread->stop();
2220 if (G1StringDedup::is_enabled()) {
2221 G1StringDedup::stop();
2222 }
2223 }
2224
2225 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2226 return HeapRegion::max_region_size();
2227 }
2228
2229 void G1CollectedHeap::post_initialize() {
2230 CollectedHeap::post_initialize();
2231 ref_processing_init();
2232 }
2233
2234 void G1CollectedHeap::ref_processing_init() {
2235 // Reference processing in G1 currently works as follows:
2236 //
2237 // * There are two reference processor instances. One is
2238 // used to record and process discovered references
2239 // during concurrent marking; the other is used to
2240 // record and process references during STW pauses
2241 // (both full and incremental).
2242 // * Both ref processors need to 'span' the entire heap as
2243 // the regions in the collection set may be dotted around.
2244 //
2245 // * For the concurrent marking ref processor:
2246 // * Reference discovery is enabled at initial marking.
2247 // * Reference discovery is disabled and the discovered
2248 // references processed etc during remarking.
2249 // * Reference discovery is MT (see below).
2250 // * Reference discovery requires a barrier (see below).
2251 // * Reference processing may or may not be MT
2252 // (depending on the value of ParallelRefProcEnabled
2253 // and ParallelGCThreads).
2254 // * A full GC disables reference discovery by the CM
2255 // ref processor and abandons any entries on it's
2256 // discovered lists.
2257 //
2258 // * For the STW processor:
2259 // * Non MT discovery is enabled at the start of a full GC.
2260 // * Processing and enqueueing during a full GC is non-MT.
2261 // * During a full GC, references are processed after marking.
2262 //
2263 // * Discovery (may or may not be MT) is enabled at the start
2264 // of an incremental evacuation pause.
2265 // * References are processed near the end of a STW evacuation pause.
2266 // * For both types of GC:
2267 // * Discovery is atomic - i.e. not concurrent.
2268 // * Reference discovery will not need a barrier.
2269
2270 MemRegion mr = reserved_region();
2271
2272 // Concurrent Mark ref processor
2273 _ref_processor_cm =
2274 new ReferenceProcessor(mr, // span
2275 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2276 // mt processing
2277 ParallelGCThreads,
2278 // degree of mt processing
2279 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2280 // mt discovery
2281 MAX2(ParallelGCThreads, ConcGCThreads),
2282 // degree of mt discovery
2283 false,
2284 // Reference discovery is not atomic
2285 &_is_alive_closure_cm);
2286 // is alive closure
2287 // (for efficiency/performance)
2288
2289 // STW ref processor
2290 _ref_processor_stw =
2291 new ReferenceProcessor(mr, // span
2292 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2293 // mt processing
2294 ParallelGCThreads,
2295 // degree of mt processing
2296 (ParallelGCThreads > 1),
2297 // mt discovery
2298 ParallelGCThreads,
2299 // degree of mt discovery
2300 true,
2301 // Reference discovery is atomic
2302 &_is_alive_closure_stw);
2303 // is alive closure
2304 // (for efficiency/performance)
2305 }
2306
2307 size_t G1CollectedHeap::capacity() const {
2308 return _hrm.length() * HeapRegion::GrainBytes;
2309 }
2310
2311 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2312 assert(!hr->is_continues_humongous(), "pre-condition");
2313 hr->reset_gc_time_stamp();
2314 if (hr->is_starts_humongous()) {
2315 uint first_index = hr->hrm_index() + 1;
2316 uint last_index = hr->last_hc_index();
2317 for (uint i = first_index; i < last_index; i += 1) {
2318 HeapRegion* chr = region_at(i);
2319 assert(chr->is_continues_humongous(), "sanity");
2320 chr->reset_gc_time_stamp();
2321 }
2322 }
2323 }
2324
2325 #ifndef PRODUCT
2326
2327 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2328 private:
2329 unsigned _gc_time_stamp;
2330 bool _failures;
2331
2332 public:
2333 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2334 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2335
2336 virtual bool doHeapRegion(HeapRegion* hr) {
2337 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2338 if (_gc_time_stamp != region_gc_time_stamp) {
2339 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2340 "expected %d", HR_FORMAT_PARAMS(hr),
2341 region_gc_time_stamp, _gc_time_stamp);
2342 _failures = true;
2343 }
2344 return false;
2345 }
2346
2347 bool failures() { return _failures; }
2348 };
2349
2350 void G1CollectedHeap::check_gc_time_stamps() {
2351 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2352 heap_region_iterate(&cl);
2353 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2354 }
2355 #endif // PRODUCT
2356
2357 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2358 DirtyCardQueue* into_cset_dcq,
2359 bool concurrent,
2360 uint worker_i) {
2361 // Clean cards in the hot card cache
2362 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2363 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2364
2365 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2366 size_t n_completed_buffers = 0;
2367 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2368 n_completed_buffers++;
2369 }
2370 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2371 dcqs.clear_n_completed_buffers();
2372 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2373 }
2374
2375
2376 // Computes the sum of the storage used by the various regions.
2377 size_t G1CollectedHeap::used() const {
2378 size_t result = _allocator->used();
2379 if (_archive_allocator != NULL) {
2380 result += _archive_allocator->used();
2381 }
2382 return result;
2383 }
2384
2385 size_t G1CollectedHeap::used_unlocked() const {
2386 return _allocator->used_unlocked();
2387 }
2388
2389 class SumUsedClosure: public HeapRegionClosure {
2390 size_t _used;
2391 public:
2392 SumUsedClosure() : _used(0) {}
2393 bool doHeapRegion(HeapRegion* r) {
2394 if (!r->is_continues_humongous()) {
2395 _used += r->used();
2396 }
2397 return false;
2398 }
2399 size_t result() { return _used; }
2400 };
2401
2402 size_t G1CollectedHeap::recalculate_used() const {
2403 double recalculate_used_start = os::elapsedTime();
2404
2405 SumUsedClosure blk;
2406 heap_region_iterate(&blk);
2407
2408 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2409 return blk.result();
2410 }
2411
2412 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2413 switch (cause) {
2414 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2415 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2416 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2417 case GCCause::_g1_humongous_allocation: return true;
2418 case GCCause::_update_allocation_context_stats_inc: return true;
2419 case GCCause::_wb_conc_mark: return true;
2420 default: return false;
2421 }
2422 }
2423
2424 #ifndef PRODUCT
2425 void G1CollectedHeap::allocate_dummy_regions() {
2426 // Let's fill up most of the region
2427 size_t word_size = HeapRegion::GrainWords - 1024;
2428 // And as a result the region we'll allocate will be humongous.
2429 guarantee(is_humongous(word_size), "sanity");
2430
2431 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2432 // Let's use the existing mechanism for the allocation
2433 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2434 AllocationContext::system());
2435 if (dummy_obj != NULL) {
2436 MemRegion mr(dummy_obj, word_size);
2437 CollectedHeap::fill_with_object(mr);
2438 } else {
2439 // If we can't allocate once, we probably cannot allocate
2440 // again. Let's get out of the loop.
2441 break;
2442 }
2443 }
2444 }
2445 #endif // !PRODUCT
2446
2447 void G1CollectedHeap::increment_old_marking_cycles_started() {
2448 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2449 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2450 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2451 _old_marking_cycles_started, _old_marking_cycles_completed));
2452
2453 _old_marking_cycles_started++;
2454 }
2455
2456 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2457 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2458
2459 // We assume that if concurrent == true, then the caller is a
2460 // concurrent thread that was joined the Suspendible Thread
2461 // Set. If there's ever a cheap way to check this, we should add an
2462 // assert here.
2463
2464 // Given that this method is called at the end of a Full GC or of a
2465 // concurrent cycle, and those can be nested (i.e., a Full GC can
2466 // interrupt a concurrent cycle), the number of full collections
2467 // completed should be either one (in the case where there was no
2468 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2469 // behind the number of full collections started.
2470
2471 // This is the case for the inner caller, i.e. a Full GC.
2472 assert(concurrent ||
2473 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2474 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2475 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2476 "is inconsistent with _old_marking_cycles_completed = %u",
2477 _old_marking_cycles_started, _old_marking_cycles_completed));
2478
2479 // This is the case for the outer caller, i.e. the concurrent cycle.
2480 assert(!concurrent ||
2481 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2482 err_msg("for outer caller (concurrent cycle): "
2483 "_old_marking_cycles_started = %u "
2484 "is inconsistent with _old_marking_cycles_completed = %u",
2485 _old_marking_cycles_started, _old_marking_cycles_completed));
2486
2487 _old_marking_cycles_completed += 1;
2488
2489 // We need to clear the "in_progress" flag in the CM thread before
2490 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2491 // is set) so that if a waiter requests another System.gc() it doesn't
2492 // incorrectly see that a marking cycle is still in progress.
2493 if (concurrent) {
2494 _cmThread->set_idle();
2495 }
2496
2497 // This notify_all() will ensure that a thread that called
2498 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2499 // and it's waiting for a full GC to finish will be woken up. It is
2500 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2501 FullGCCount_lock->notify_all();
2502 }
2503
2504 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2505 collector_state()->set_concurrent_cycle_started(true);
2506 _gc_timer_cm->register_gc_start(start_time);
2507
2508 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2509 trace_heap_before_gc(_gc_tracer_cm);
2510 }
2511
2512 void G1CollectedHeap::register_concurrent_cycle_end() {
2513 if (collector_state()->concurrent_cycle_started()) {
2514 if (_cm->has_aborted()) {
2515 _gc_tracer_cm->report_concurrent_mode_failure();
2516 }
2517
2518 _gc_timer_cm->register_gc_end();
2519 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2520
2521 // Clear state variables to prepare for the next concurrent cycle.
2522 collector_state()->set_concurrent_cycle_started(false);
2523 _heap_summary_sent = false;
2524 }
2525 }
2526
2527 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2528 if (collector_state()->concurrent_cycle_started()) {
2529 // This function can be called when:
2530 // the cleanup pause is run
2531 // the concurrent cycle is aborted before the cleanup pause.
2532 // the concurrent cycle is aborted after the cleanup pause,
2533 // but before the concurrent cycle end has been registered.
2534 // Make sure that we only send the heap information once.
2535 if (!_heap_summary_sent) {
2536 trace_heap_after_gc(_gc_tracer_cm);
2537 _heap_summary_sent = true;
2538 }
2539 }
2540 }
2541
2542 void G1CollectedHeap::collect(GCCause::Cause cause) {
2543 assert_heap_not_locked();
2544
2545 uint gc_count_before;
2546 uint old_marking_count_before;
2547 uint full_gc_count_before;
2548 bool retry_gc;
2549
2550 do {
2551 retry_gc = false;
2552
2553 {
2554 MutexLocker ml(Heap_lock);
2555
2556 // Read the GC count while holding the Heap_lock
2557 gc_count_before = total_collections();
2558 full_gc_count_before = total_full_collections();
2559 old_marking_count_before = _old_marking_cycles_started;
2560 }
2561
2562 if (should_do_concurrent_full_gc(cause)) {
2563 // Schedule an initial-mark evacuation pause that will start a
2564 // concurrent cycle. We're setting word_size to 0 which means that
2565 // we are not requesting a post-GC allocation.
2566 VM_G1IncCollectionPause op(gc_count_before,
2567 0, /* word_size */
2568 true, /* should_initiate_conc_mark */
2569 g1_policy()->max_pause_time_ms(),
2570 cause);
2571 op.set_allocation_context(AllocationContext::current());
2572
2573 VMThread::execute(&op);
2574 if (!op.pause_succeeded()) {
2575 if (old_marking_count_before == _old_marking_cycles_started) {
2576 retry_gc = op.should_retry_gc();
2577 } else {
2578 // A Full GC happened while we were trying to schedule the
2579 // initial-mark GC. No point in starting a new cycle given
2580 // that the whole heap was collected anyway.
2581 }
2582
2583 if (retry_gc) {
2584 if (GC_locker::is_active_and_needs_gc()) {
2585 GC_locker::stall_until_clear();
2586 }
2587 }
2588 }
2589 } else {
2590 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2591 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2592
2593 // Schedule a standard evacuation pause. We're setting word_size
2594 // to 0 which means that we are not requesting a post-GC allocation.
2595 VM_G1IncCollectionPause op(gc_count_before,
2596 0, /* word_size */
2597 false, /* should_initiate_conc_mark */
2598 g1_policy()->max_pause_time_ms(),
2599 cause);
2600 VMThread::execute(&op);
2601 } else {
2602 // Schedule a Full GC.
2603 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2604 VMThread::execute(&op);
2605 }
2606 }
2607 } while (retry_gc);
2608 }
2609
2610 bool G1CollectedHeap::is_in(const void* p) const {
2611 if (_hrm.reserved().contains(p)) {
2612 // Given that we know that p is in the reserved space,
2613 // heap_region_containing_raw() should successfully
2614 // return the containing region.
2615 HeapRegion* hr = heap_region_containing_raw(p);
2616 return hr->is_in(p);
2617 } else {
2618 return false;
2619 }
2620 }
2621
2622 #ifdef ASSERT
2623 bool G1CollectedHeap::is_in_exact(const void* p) const {
2624 bool contains = reserved_region().contains(p);
2625 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2626 if (contains && available) {
2627 return true;
2628 } else {
2629 return false;
2630 }
2631 }
2632 #endif
2633
2634 // Iteration functions.
2635
2636 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2637
2638 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2639 ExtendedOopClosure* _cl;
2640 public:
2641 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2642 bool doHeapRegion(HeapRegion* r) {
2643 if (!r->is_continues_humongous()) {
2644 r->oop_iterate(_cl);
2645 }
2646 return false;
2647 }
2648 };
2649
2650 // Iterates an ObjectClosure over all objects within a HeapRegion.
2651
2652 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2653 ObjectClosure* _cl;
2654 public:
2655 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2656 bool doHeapRegion(HeapRegion* r) {
2657 if (!r->is_continues_humongous()) {
2658 r->object_iterate(_cl);
2659 }
2660 return false;
2661 }
2662 };
2663
2664 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2665 IterateObjectClosureRegionClosure blk(cl);
2666 heap_region_iterate(&blk);
2667 }
2668
2669 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2670 _hrm.iterate(cl);
2671 }
2672
2673 void
2674 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2675 uint worker_id,
2676 HeapRegionClaimer *hrclaimer,
2677 bool concurrent) const {
2678 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2679 }
2680
2681 // Clear the cached CSet starting regions and (more importantly)
2682 // the time stamps. Called when we reset the GC time stamp.
2683 void G1CollectedHeap::clear_cset_start_regions() {
2684 assert(_worker_cset_start_region != NULL, "sanity");
2685 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2686
2687 for (uint i = 0; i < ParallelGCThreads; i++) {
2688 _worker_cset_start_region[i] = NULL;
2689 _worker_cset_start_region_time_stamp[i] = 0;
2690 }
2691 }
2692
2693 // Given the id of a worker, obtain or calculate a suitable
2694 // starting region for iterating over the current collection set.
2695 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2696 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2697
2698 HeapRegion* result = NULL;
2699 unsigned gc_time_stamp = get_gc_time_stamp();
2700
2701 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2702 // Cached starting region for current worker was set
2703 // during the current pause - so it's valid.
2704 // Note: the cached starting heap region may be NULL
2705 // (when the collection set is empty).
2706 result = _worker_cset_start_region[worker_i];
2707 assert(result == NULL || result->in_collection_set(), "sanity");
2708 return result;
2709 }
2710
2711 // The cached entry was not valid so let's calculate
2712 // a suitable starting heap region for this worker.
2713
2714 // We want the parallel threads to start their collection
2715 // set iteration at different collection set regions to
2716 // avoid contention.
2717 // If we have:
2718 // n collection set regions
2719 // p threads
2720 // Then thread t will start at region floor ((t * n) / p)
2721
2722 result = g1_policy()->collection_set();
2723 uint cs_size = g1_policy()->cset_region_length();
2724 uint active_workers = workers()->active_workers();
2725
2726 uint end_ind = (cs_size * worker_i) / active_workers;
2727 uint start_ind = 0;
2728
2729 if (worker_i > 0 &&
2730 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2731 // Previous workers starting region is valid
2732 // so let's iterate from there
2733 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2734 result = _worker_cset_start_region[worker_i - 1];
2735 }
2736
2737 for (uint i = start_ind; i < end_ind; i++) {
2738 result = result->next_in_collection_set();
2739 }
2740
2741 // Note: the calculated starting heap region may be NULL
2742 // (when the collection set is empty).
2743 assert(result == NULL || result->in_collection_set(), "sanity");
2744 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2745 "should be updated only once per pause");
2746 _worker_cset_start_region[worker_i] = result;
2747 OrderAccess::storestore();
2748 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2749 return result;
2750 }
2751
2752 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2753 HeapRegion* r = g1_policy()->collection_set();
2754 while (r != NULL) {
2755 HeapRegion* next = r->next_in_collection_set();
2756 if (cl->doHeapRegion(r)) {
2757 cl->incomplete();
2758 return;
2759 }
2760 r = next;
2761 }
2762 }
2763
2764 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2765 HeapRegionClosure *cl) {
2766 if (r == NULL) {
2767 // The CSet is empty so there's nothing to do.
2768 return;
2769 }
2770
2771 assert(r->in_collection_set(),
2772 "Start region must be a member of the collection set.");
2773 HeapRegion* cur = r;
2774 while (cur != NULL) {
2775 HeapRegion* next = cur->next_in_collection_set();
2776 if (cl->doHeapRegion(cur) && false) {
2777 cl->incomplete();
2778 return;
2779 }
2780 cur = next;
2781 }
2782 cur = g1_policy()->collection_set();
2783 while (cur != r) {
2784 HeapRegion* next = cur->next_in_collection_set();
2785 if (cl->doHeapRegion(cur) && false) {
2786 cl->incomplete();
2787 return;
2788 }
2789 cur = next;
2790 }
2791 }
2792
2793 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2794 HeapRegion* result = _hrm.next_region_in_heap(from);
2795 while (result != NULL && result->is_pinned()) {
2796 result = _hrm.next_region_in_heap(result);
2797 }
2798 return result;
2799 }
2800
2801 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2802 HeapRegion* hr = heap_region_containing(addr);
2803 return hr->block_start(addr);
2804 }
2805
2806 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2807 HeapRegion* hr = heap_region_containing(addr);
2808 return hr->block_size(addr);
2809 }
2810
2811 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2812 HeapRegion* hr = heap_region_containing(addr);
2813 return hr->block_is_obj(addr);
2814 }
2815
2816 bool G1CollectedHeap::supports_tlab_allocation() const {
2817 return true;
2818 }
2819
2820 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2821 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2822 }
2823
2824 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2825 return young_list()->eden_used_bytes();
2826 }
2827
2828 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2829 // must be smaller than the humongous object limit.
2830 size_t G1CollectedHeap::max_tlab_size() const {
2831 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2832 }
2833
2834 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2835 // Return the remaining space in the cur alloc region, but not less than
2836 // the min TLAB size.
2837
2838 // Also, this value can be at most the humongous object threshold,
2839 // since we can't allow tlabs to grow big enough to accommodate
2840 // humongous objects.
2841
2842 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2843 size_t max_tlab = max_tlab_size() * wordSize;
2844 if (hr == NULL) {
2845 return max_tlab;
2846 } else {
2847 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2848 }
2849 }
2850
2851 size_t G1CollectedHeap::max_capacity() const {
2852 return _hrm.reserved().byte_size();
2853 }
2854
2855 jlong G1CollectedHeap::millis_since_last_gc() {
2856 // assert(false, "NYI");
2857 return 0;
2858 }
2859
2860 void G1CollectedHeap::prepare_for_verify() {
2861 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2862 ensure_parsability(false);
2863 }
2864 g1_rem_set()->prepare_for_verify();
2865 }
2866
2867 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2868 VerifyOption vo) {
2869 switch (vo) {
2870 case VerifyOption_G1UsePrevMarking:
2871 return hr->obj_allocated_since_prev_marking(obj);
2872 case VerifyOption_G1UseNextMarking:
2873 return hr->obj_allocated_since_next_marking(obj);
2874 case VerifyOption_G1UseMarkWord:
2875 return false;
2876 default:
2877 ShouldNotReachHere();
2878 }
2879 return false; // keep some compilers happy
2880 }
2881
2882 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2883 switch (vo) {
2884 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2885 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2886 case VerifyOption_G1UseMarkWord: return NULL;
2887 default: ShouldNotReachHere();
2888 }
2889 return NULL; // keep some compilers happy
2890 }
2891
2892 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2893 switch (vo) {
2894 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2895 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2896 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2897 default: ShouldNotReachHere();
2898 }
2899 return false; // keep some compilers happy
2900 }
2901
2902 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2903 switch (vo) {
2904 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2905 case VerifyOption_G1UseNextMarking: return "NTAMS";
2906 case VerifyOption_G1UseMarkWord: return "NONE";
2907 default: ShouldNotReachHere();
2908 }
2909 return NULL; // keep some compilers happy
2910 }
2911
2912 class VerifyRootsClosure: public OopClosure {
2913 private:
2914 G1CollectedHeap* _g1h;
2915 VerifyOption _vo;
2916 bool _failures;
2917 public:
2918 // _vo == UsePrevMarking -> use "prev" marking information,
2919 // _vo == UseNextMarking -> use "next" marking information,
2920 // _vo == UseMarkWord -> use mark word from object header.
2921 VerifyRootsClosure(VerifyOption vo) :
2922 _g1h(G1CollectedHeap::heap()),
2923 _vo(vo),
2924 _failures(false) { }
2925
2926 bool failures() { return _failures; }
2927
2928 template <class T> void do_oop_nv(T* p) {
2929 T heap_oop = oopDesc::load_heap_oop(p);
2930 if (!oopDesc::is_null(heap_oop)) {
2931 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2932 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2933 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2934 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2935 if (_vo == VerifyOption_G1UseMarkWord) {
2936 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2937 }
2938 obj->print_on(gclog_or_tty);
2939 _failures = true;
2940 }
2941 }
2942 }
2943
2944 void do_oop(oop* p) { do_oop_nv(p); }
2945 void do_oop(narrowOop* p) { do_oop_nv(p); }
2946 };
2947
2948 class G1VerifyCodeRootOopClosure: public OopClosure {
2949 G1CollectedHeap* _g1h;
2950 OopClosure* _root_cl;
2951 nmethod* _nm;
2952 VerifyOption _vo;
2953 bool _failures;
2954
2955 template <class T> void do_oop_work(T* p) {
2956 // First verify that this root is live
2957 _root_cl->do_oop(p);
2958
2959 if (!G1VerifyHeapRegionCodeRoots) {
2960 // We're not verifying the code roots attached to heap region.
2961 return;
2962 }
2963
2964 // Don't check the code roots during marking verification in a full GC
2965 if (_vo == VerifyOption_G1UseMarkWord) {
2966 return;
2967 }
2968
2969 // Now verify that the current nmethod (which contains p) is
2970 // in the code root list of the heap region containing the
2971 // object referenced by p.
2972
2973 T heap_oop = oopDesc::load_heap_oop(p);
2974 if (!oopDesc::is_null(heap_oop)) {
2975 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2976
2977 // Now fetch the region containing the object
2978 HeapRegion* hr = _g1h->heap_region_containing(obj);
2979 HeapRegionRemSet* hrrs = hr->rem_set();
2980 // Verify that the strong code root list for this region
2981 // contains the nmethod
2982 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2983 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2984 "from nmethod " PTR_FORMAT " not in strong "
2985 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2986 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2987 _failures = true;
2988 }
2989 }
2990 }
2991
2992 public:
2993 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2994 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2995
2996 void do_oop(oop* p) { do_oop_work(p); }
2997 void do_oop(narrowOop* p) { do_oop_work(p); }
2998
2999 void set_nmethod(nmethod* nm) { _nm = nm; }
3000 bool failures() { return _failures; }
3001 };
3002
3003 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3004 G1VerifyCodeRootOopClosure* _oop_cl;
3005
3006 public:
3007 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3008 _oop_cl(oop_cl) {}
3009
3010 void do_code_blob(CodeBlob* cb) {
3011 nmethod* nm = cb->as_nmethod_or_null();
3012 if (nm != NULL) {
3013 _oop_cl->set_nmethod(nm);
3014 nm->oops_do(_oop_cl);
3015 }
3016 }
3017 };
3018
3019 class YoungRefCounterClosure : public OopClosure {
3020 G1CollectedHeap* _g1h;
3021 int _count;
3022 public:
3023 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3024 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3025 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3026
3027 int count() { return _count; }
3028 void reset_count() { _count = 0; };
3029 };
3030
3031 class VerifyKlassClosure: public KlassClosure {
3032 YoungRefCounterClosure _young_ref_counter_closure;
3033 OopClosure *_oop_closure;
3034 public:
3035 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3036 void do_klass(Klass* k) {
3037 k->oops_do(_oop_closure);
3038
3039 _young_ref_counter_closure.reset_count();
3040 k->oops_do(&_young_ref_counter_closure);
3041 if (_young_ref_counter_closure.count() > 0) {
3042 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3043 }
3044 }
3045 };
3046
3047 class VerifyLivenessOopClosure: public OopClosure {
3048 G1CollectedHeap* _g1h;
3049 VerifyOption _vo;
3050 public:
3051 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3052 _g1h(g1h), _vo(vo)
3053 { }
3054 void do_oop(narrowOop *p) { do_oop_work(p); }
3055 void do_oop( oop *p) { do_oop_work(p); }
3056
3057 template <class T> void do_oop_work(T *p) {
3058 oop obj = oopDesc::load_decode_heap_oop(p);
3059 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3060 "Dead object referenced by a not dead object");
3061 }
3062 };
3063
3064 class VerifyObjsInRegionClosure: public ObjectClosure {
3065 private:
3066 G1CollectedHeap* _g1h;
3067 size_t _live_bytes;
3068 HeapRegion *_hr;
3069 VerifyOption _vo;
3070 public:
3071 // _vo == UsePrevMarking -> use "prev" marking information,
3072 // _vo == UseNextMarking -> use "next" marking information,
3073 // _vo == UseMarkWord -> use mark word from object header.
3074 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3075 : _live_bytes(0), _hr(hr), _vo(vo) {
3076 _g1h = G1CollectedHeap::heap();
3077 }
3078 void do_object(oop o) {
3079 VerifyLivenessOopClosure isLive(_g1h, _vo);
3080 assert(o != NULL, "Huh?");
3081 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3082 // If the object is alive according to the mark word,
3083 // then verify that the marking information agrees.
3084 // Note we can't verify the contra-positive of the
3085 // above: if the object is dead (according to the mark
3086 // word), it may not be marked, or may have been marked
3087 // but has since became dead, or may have been allocated
3088 // since the last marking.
3089 if (_vo == VerifyOption_G1UseMarkWord) {
3090 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3091 }
3092
3093 o->oop_iterate_no_header(&isLive);
3094 if (!_hr->obj_allocated_since_prev_marking(o)) {
3095 size_t obj_size = o->size(); // Make sure we don't overflow
3096 _live_bytes += (obj_size * HeapWordSize);
3097 }
3098 }
3099 }
3100 size_t live_bytes() { return _live_bytes; }
3101 };
3102
3103 class VerifyArchiveOopClosure: public OopClosure {
3104 public:
3105 VerifyArchiveOopClosure(HeapRegion *hr) { }
3106 void do_oop(narrowOop *p) { do_oop_work(p); }
3107 void do_oop( oop *p) { do_oop_work(p); }
3108
3109 template <class T> void do_oop_work(T *p) {
3110 oop obj = oopDesc::load_decode_heap_oop(p);
3111 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3112 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3113 p2i(p), p2i(obj)));
3114 }
3115 };
3116
3117 class VerifyArchiveRegionClosure: public ObjectClosure {
3118 public:
3119 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3120 // Verify that all object pointers are to archive regions.
3121 void do_object(oop o) {
3122 VerifyArchiveOopClosure checkOop(NULL);
3123 assert(o != NULL, "Should not be here for NULL oops");
3124 o->oop_iterate_no_header(&checkOop);
3125 }
3126 };
3127
3128 class VerifyRegionClosure: public HeapRegionClosure {
3129 private:
3130 bool _par;
3131 VerifyOption _vo;
3132 bool _failures;
3133 public:
3134 // _vo == UsePrevMarking -> use "prev" marking information,
3135 // _vo == UseNextMarking -> use "next" marking information,
3136 // _vo == UseMarkWord -> use mark word from object header.
3137 VerifyRegionClosure(bool par, VerifyOption vo)
3138 : _par(par),
3139 _vo(vo),
3140 _failures(false) {}
3141
3142 bool failures() {
3143 return _failures;
3144 }
3145
3146 bool doHeapRegion(HeapRegion* r) {
3147 // For archive regions, verify there are no heap pointers to
3148 // non-pinned regions. For all others, verify liveness info.
3149 if (r->is_archive()) {
3150 VerifyArchiveRegionClosure verify_oop_pointers(r);
3151 r->object_iterate(&verify_oop_pointers);
3152 return true;
3153 }
3154 if (!r->is_continues_humongous()) {
3155 bool failures = false;
3156 r->verify(_vo, &failures);
3157 if (failures) {
3158 _failures = true;
3159 } else {
3160 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3161 r->object_iterate(¬_dead_yet_cl);
3162 if (_vo != VerifyOption_G1UseNextMarking) {
3163 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3164 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3165 "max_live_bytes " SIZE_FORMAT " "
3166 "< calculated " SIZE_FORMAT,
3167 p2i(r->bottom()), p2i(r->end()),
3168 r->max_live_bytes(),
3169 not_dead_yet_cl.live_bytes());
3170 _failures = true;
3171 }
3172 } else {
3173 // When vo == UseNextMarking we cannot currently do a sanity
3174 // check on the live bytes as the calculation has not been
3175 // finalized yet.
3176 }
3177 }
3178 }
3179 return false; // stop the region iteration if we hit a failure
3180 }
3181 };
3182
3183 // This is the task used for parallel verification of the heap regions
3184
3185 class G1ParVerifyTask: public AbstractGangTask {
3186 private:
3187 G1CollectedHeap* _g1h;
3188 VerifyOption _vo;
3189 bool _failures;
3190 HeapRegionClaimer _hrclaimer;
3191
3192 public:
3193 // _vo == UsePrevMarking -> use "prev" marking information,
3194 // _vo == UseNextMarking -> use "next" marking information,
3195 // _vo == UseMarkWord -> use mark word from object header.
3196 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3197 AbstractGangTask("Parallel verify task"),
3198 _g1h(g1h),
3199 _vo(vo),
3200 _failures(false),
3201 _hrclaimer(g1h->workers()->active_workers()) {}
3202
3203 bool failures() {
3204 return _failures;
3205 }
3206
3207 void work(uint worker_id) {
3208 HandleMark hm;
3209 VerifyRegionClosure blk(true, _vo);
3210 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3211 if (blk.failures()) {
3212 _failures = true;
3213 }
3214 }
3215 };
3216
3217 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3218 if (SafepointSynchronize::is_at_safepoint()) {
3219 assert(Thread::current()->is_VM_thread(),
3220 "Expected to be executed serially by the VM thread at this point");
3221
3222 if (!silent) { gclog_or_tty->print("Roots "); }
3223 VerifyRootsClosure rootsCl(vo);
3224 VerifyKlassClosure klassCl(this, &rootsCl);
3225 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3226
3227 // We apply the relevant closures to all the oops in the
3228 // system dictionary, class loader data graph, the string table
3229 // and the nmethods in the code cache.
3230 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3231 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3232
3233 {
3234 G1RootProcessor root_processor(this, 1);
3235 root_processor.process_all_roots(&rootsCl,
3236 &cldCl,
3237 &blobsCl);
3238 }
3239
3240 bool failures = rootsCl.failures() || codeRootsCl.failures();
3241
3242 if (vo != VerifyOption_G1UseMarkWord) {
3243 // If we're verifying during a full GC then the region sets
3244 // will have been torn down at the start of the GC. Therefore
3245 // verifying the region sets will fail. So we only verify
3246 // the region sets when not in a full GC.
3247 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3248 verify_region_sets();
3249 }
3250
3251 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3252 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3253
3254 G1ParVerifyTask task(this, vo);
3255 workers()->run_task(&task);
3256 if (task.failures()) {
3257 failures = true;
3258 }
3259
3260 } else {
3261 VerifyRegionClosure blk(false, vo);
3262 heap_region_iterate(&blk);
3263 if (blk.failures()) {
3264 failures = true;
3265 }
3266 }
3267
3268 if (G1StringDedup::is_enabled()) {
3269 if (!silent) gclog_or_tty->print("StrDedup ");
3270 G1StringDedup::verify();
3271 }
3272
3273 if (failures) {
3274 gclog_or_tty->print_cr("Heap:");
3275 // It helps to have the per-region information in the output to
3276 // help us track down what went wrong. This is why we call
3277 // print_extended_on() instead of print_on().
3278 print_extended_on(gclog_or_tty);
3279 gclog_or_tty->cr();
3280 gclog_or_tty->flush();
3281 }
3282 guarantee(!failures, "there should not have been any failures");
3283 } else {
3284 if (!silent) {
3285 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3286 if (G1StringDedup::is_enabled()) {
3287 gclog_or_tty->print(", StrDedup");
3288 }
3289 gclog_or_tty->print(") ");
3290 }
3291 }
3292 }
3293
3294 void G1CollectedHeap::verify(bool silent) {
3295 verify(silent, VerifyOption_G1UsePrevMarking);
3296 }
3297
3298 double G1CollectedHeap::verify(bool guard, const char* msg) {
3299 double verify_time_ms = 0.0;
3300
3301 if (guard && total_collections() >= VerifyGCStartAt) {
3302 double verify_start = os::elapsedTime();
3303 HandleMark hm; // Discard invalid handles created during verification
3304 prepare_for_verify();
3305 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3306 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3307 }
3308
3309 return verify_time_ms;
3310 }
3311
3312 void G1CollectedHeap::verify_before_gc() {
3313 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3314 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3315 }
3316
3317 void G1CollectedHeap::verify_after_gc() {
3318 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3319 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3320 }
3321
3322 class PrintRegionClosure: public HeapRegionClosure {
3323 outputStream* _st;
3324 public:
3325 PrintRegionClosure(outputStream* st) : _st(st) {}
3326 bool doHeapRegion(HeapRegion* r) {
3327 r->print_on(_st);
3328 return false;
3329 }
3330 };
3331
3332 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3333 const HeapRegion* hr,
3334 const VerifyOption vo) const {
3335 switch (vo) {
3336 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3337 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3338 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3339 default: ShouldNotReachHere();
3340 }
3341 return false; // keep some compilers happy
3342 }
3343
3344 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3345 const VerifyOption vo) const {
3346 switch (vo) {
3347 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3348 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3349 case VerifyOption_G1UseMarkWord: {
3350 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3351 return !obj->is_gc_marked() && !hr->is_archive();
3352 }
3353 default: ShouldNotReachHere();
3354 }
3355 return false; // keep some compilers happy
3356 }
3357
3358 void G1CollectedHeap::print_on(outputStream* st) const {
3359 st->print(" %-20s", "garbage-first heap");
3360 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3361 capacity()/K, used_unlocked()/K);
3362 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3363 p2i(_hrm.reserved().start()),
3364 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3365 p2i(_hrm.reserved().end()));
3366 st->cr();
3367 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3368 uint young_regions = _young_list->length();
3369 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3370 (size_t) young_regions * HeapRegion::GrainBytes / K);
3371 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3372 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3373 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3374 st->cr();
3375 MetaspaceAux::print_on(st);
3376 }
3377
3378 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3379 print_on(st);
3380
3381 // Print the per-region information.
3382 st->cr();
3383 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3384 "HS=humongous(starts), HC=humongous(continues), "
3385 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3386 "PTAMS=previous top-at-mark-start, "
3387 "NTAMS=next top-at-mark-start)");
3388 PrintRegionClosure blk(st);
3389 heap_region_iterate(&blk);
3390 }
3391
3392 void G1CollectedHeap::print_on_error(outputStream* st) const {
3393 this->CollectedHeap::print_on_error(st);
3394
3395 if (_cm != NULL) {
3396 st->cr();
3397 _cm->print_on_error(st);
3398 }
3399 }
3400
3401 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3402 workers()->print_worker_threads_on(st);
3403 _cmThread->print_on(st);
3404 st->cr();
3405 _cm->print_worker_threads_on(st);
3406 _cg1r->print_worker_threads_on(st);
3407 if (G1StringDedup::is_enabled()) {
3408 G1StringDedup::print_worker_threads_on(st);
3409 }
3410 }
3411
3412 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3413 workers()->threads_do(tc);
3414 tc->do_thread(_cmThread);
3415 _cg1r->threads_do(tc);
3416 if (G1StringDedup::is_enabled()) {
3417 G1StringDedup::threads_do(tc);
3418 }
3419 }
3420
3421 void G1CollectedHeap::print_tracing_info() const {
3422 // We'll overload this to mean "trace GC pause statistics."
3423 if (TraceYoungGenTime || TraceOldGenTime) {
3424 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3425 // to that.
3426 g1_policy()->print_tracing_info();
3427 }
3428 if (G1SummarizeRSetStats) {
3429 g1_rem_set()->print_summary_info();
3430 }
3431 if (G1SummarizeConcMark) {
3432 concurrent_mark()->print_summary_info();
3433 }
3434 g1_policy()->print_yg_surv_rate_info();
3435 }
3436
3437 #ifndef PRODUCT
3438 // Helpful for debugging RSet issues.
3439
3440 class PrintRSetsClosure : public HeapRegionClosure {
3441 private:
3442 const char* _msg;
3443 size_t _occupied_sum;
3444
3445 public:
3446 bool doHeapRegion(HeapRegion* r) {
3447 HeapRegionRemSet* hrrs = r->rem_set();
3448 size_t occupied = hrrs->occupied();
3449 _occupied_sum += occupied;
3450
3451 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3452 HR_FORMAT_PARAMS(r));
3453 if (occupied == 0) {
3454 gclog_or_tty->print_cr(" RSet is empty");
3455 } else {
3456 hrrs->print();
3457 }
3458 gclog_or_tty->print_cr("----------");
3459 return false;
3460 }
3461
3462 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3463 gclog_or_tty->cr();
3464 gclog_or_tty->print_cr("========================================");
3465 gclog_or_tty->print_cr("%s", msg);
3466 gclog_or_tty->cr();
3467 }
3468
3469 ~PrintRSetsClosure() {
3470 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3471 gclog_or_tty->print_cr("========================================");
3472 gclog_or_tty->cr();
3473 }
3474 };
3475
3476 void G1CollectedHeap::print_cset_rsets() {
3477 PrintRSetsClosure cl("Printing CSet RSets");
3478 collection_set_iterate(&cl);
3479 }
3480
3481 void G1CollectedHeap::print_all_rsets() {
3482 PrintRSetsClosure cl("Printing All RSets");;
3483 heap_region_iterate(&cl);
3484 }
3485 #endif // PRODUCT
3486
3487 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3488 YoungList* young_list = heap()->young_list();
3489
3490 size_t eden_used_bytes = young_list->eden_used_bytes();
3491 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3492
3493 size_t eden_capacity_bytes =
3494 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3495
3496 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3497 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3498 }
3499
3500 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3501 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3502 gc_tracer->report_gc_heap_summary(when, heap_summary);
3503
3504 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3505 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3506 }
3507
3508
3509 G1CollectedHeap* G1CollectedHeap::heap() {
3510 CollectedHeap* heap = Universe::heap();
3511 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3512 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3513 return (G1CollectedHeap*)heap;
3514 }
3515
3516 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3517 // always_do_update_barrier = false;
3518 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3519 // Fill TLAB's and such
3520 accumulate_statistics_all_tlabs();
3521 ensure_parsability(true);
3522
3523 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3524 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3525 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3526 }
3527 }
3528
3529 void G1CollectedHeap::gc_epilogue(bool full) {
3530
3531 if (G1SummarizeRSetStats &&
3532 (G1SummarizeRSetStatsPeriod > 0) &&
3533 // we are at the end of the GC. Total collections has already been increased.
3534 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3535 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3536 }
3537
3538 // FIXME: what is this about?
3539 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3540 // is set.
3541 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3542 "derived pointer present"));
3543 // always_do_update_barrier = true;
3544
3545 resize_all_tlabs();
3546 allocation_context_stats().update(full);
3547
3548 // We have just completed a GC. Update the soft reference
3549 // policy with the new heap occupancy
3550 Universe::update_heap_info_at_gc();
3551 }
3552
3553 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3554 uint gc_count_before,
3555 bool* succeeded,
3556 GCCause::Cause gc_cause) {
3557 assert_heap_not_locked_and_not_at_safepoint();
3558 g1_policy()->record_stop_world_start();
3559 VM_G1IncCollectionPause op(gc_count_before,
3560 word_size,
3561 false, /* should_initiate_conc_mark */
3562 g1_policy()->max_pause_time_ms(),
3563 gc_cause);
3564
3565 op.set_allocation_context(AllocationContext::current());
3566 VMThread::execute(&op);
3567
3568 HeapWord* result = op.result();
3569 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3570 assert(result == NULL || ret_succeeded,
3571 "the result should be NULL if the VM did not succeed");
3572 *succeeded = ret_succeeded;
3573
3574 assert_heap_not_locked();
3575 return result;
3576 }
3577
3578 void
3579 G1CollectedHeap::doConcurrentMark() {
3580 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3581 if (!_cmThread->in_progress()) {
3582 _cmThread->set_started();
3583 CGC_lock->notify();
3584 }
3585 }
3586
3587 size_t G1CollectedHeap::pending_card_num() {
3588 size_t extra_cards = 0;
3589 JavaThread *curr = Threads::first();
3590 while (curr != NULL) {
3591 DirtyCardQueue& dcq = curr->dirty_card_queue();
3592 extra_cards += dcq.size();
3593 curr = curr->next();
3594 }
3595 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3596 size_t buffer_size = dcqs.buffer_size();
3597 size_t buffer_num = dcqs.completed_buffers_num();
3598
3599 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3600 // in bytes - not the number of 'entries'. We need to convert
3601 // into a number of cards.
3602 return (buffer_size * buffer_num + extra_cards) / oopSize;
3603 }
3604
3605 size_t G1CollectedHeap::cards_scanned() {
3606 return g1_rem_set()->cardsScanned();
3607 }
3608
3609 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3610 private:
3611 size_t _total_humongous;
3612 size_t _candidate_humongous;
3613
3614 DirtyCardQueue _dcq;
3615
3616 // We don't nominate objects with many remembered set entries, on
3617 // the assumption that such objects are likely still live.
3618 bool is_remset_small(HeapRegion* region) const {
3619 HeapRegionRemSet* const rset = region->rem_set();
3620 return G1EagerReclaimHumongousObjectsWithStaleRefs
3621 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3622 : rset->is_empty();
3623 }
3624
3625 bool is_typeArray_region(HeapRegion* region) const {
3626 return oop(region->bottom())->is_typeArray();
3627 }
3628
3629 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3630 assert(region->is_starts_humongous(), "Must start a humongous object");
3631
3632 // Candidate selection must satisfy the following constraints
3633 // while concurrent marking is in progress:
3634 //
3635 // * In order to maintain SATB invariants, an object must not be
3636 // reclaimed if it was allocated before the start of marking and
3637 // has not had its references scanned. Such an object must have
3638 // its references (including type metadata) scanned to ensure no
3639 // live objects are missed by the marking process. Objects
3640 // allocated after the start of concurrent marking don't need to
3641 // be scanned.
3642 //
3643 // * An object must not be reclaimed if it is on the concurrent
3644 // mark stack. Objects allocated after the start of concurrent
3645 // marking are never pushed on the mark stack.
3646 //
3647 // Nominating only objects allocated after the start of concurrent
3648 // marking is sufficient to meet both constraints. This may miss
3649 // some objects that satisfy the constraints, but the marking data
3650 // structures don't support efficiently performing the needed
3651 // additional tests or scrubbing of the mark stack.
3652 //
3653 // However, we presently only nominate is_typeArray() objects.
3654 // A humongous object containing references induces remembered
3655 // set entries on other regions. In order to reclaim such an
3656 // object, those remembered sets would need to be cleaned up.
3657 //
3658 // We also treat is_typeArray() objects specially, allowing them
3659 // to be reclaimed even if allocated before the start of
3660 // concurrent mark. For this we rely on mark stack insertion to
3661 // exclude is_typeArray() objects, preventing reclaiming an object
3662 // that is in the mark stack. We also rely on the metadata for
3663 // such objects to be built-in and so ensured to be kept live.
3664 // Frequent allocation and drop of large binary blobs is an
3665 // important use case for eager reclaim, and this special handling
3666 // may reduce needed headroom.
3667
3668 return is_typeArray_region(region) && is_remset_small(region);
3669 }
3670
3671 public:
3672 RegisterHumongousWithInCSetFastTestClosure()
3673 : _total_humongous(0),
3674 _candidate_humongous(0),
3675 _dcq(&JavaThread::dirty_card_queue_set()) {
3676 }
3677
3678 virtual bool doHeapRegion(HeapRegion* r) {
3679 if (!r->is_starts_humongous()) {
3680 return false;
3681 }
3682 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3683
3684 bool is_candidate = humongous_region_is_candidate(g1h, r);
3685 uint rindex = r->hrm_index();
3686 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3687 if (is_candidate) {
3688 _candidate_humongous++;
3689 g1h->register_humongous_region_with_cset(rindex);
3690 // Is_candidate already filters out humongous object with large remembered sets.
3691 // If we have a humongous object with a few remembered sets, we simply flush these
3692 // remembered set entries into the DCQS. That will result in automatic
3693 // re-evaluation of their remembered set entries during the following evacuation
3694 // phase.
3695 if (!r->rem_set()->is_empty()) {
3696 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3697 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3698 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3699 HeapRegionRemSetIterator hrrs(r->rem_set());
3700 size_t card_index;
3701 while (hrrs.has_next(card_index)) {
3702 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3703 // The remembered set might contain references to already freed
3704 // regions. Filter out such entries to avoid failing card table
3705 // verification.
3706 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3707 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3708 *card_ptr = CardTableModRefBS::dirty_card_val();
3709 _dcq.enqueue(card_ptr);
3710 }
3711 }
3712 }
3713 r->rem_set()->clear_locked();
3714 }
3715 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3716 }
3717 _total_humongous++;
3718
3719 return false;
3720 }
3721
3722 size_t total_humongous() const { return _total_humongous; }
3723 size_t candidate_humongous() const { return _candidate_humongous; }
3724
3725 void flush_rem_set_entries() { _dcq.flush(); }
3726 };
3727
3728 void G1CollectedHeap::register_humongous_regions_with_cset() {
3729 if (!G1EagerReclaimHumongousObjects) {
3730 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3731 return;
3732 }
3733 double time = os::elapsed_counter();
3734
3735 // Collect reclaim candidate information and register candidates with cset.
3736 RegisterHumongousWithInCSetFastTestClosure cl;
3737 heap_region_iterate(&cl);
3738
3739 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3740 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3741 cl.total_humongous(),
3742 cl.candidate_humongous());
3743 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3744
3745 // Finally flush all remembered set entries to re-check into the global DCQS.
3746 cl.flush_rem_set_entries();
3747 }
3748
3749 void
3750 G1CollectedHeap::setup_surviving_young_words() {
3751 assert(_surviving_young_words == NULL, "pre-condition");
3752 uint array_length = g1_policy()->young_cset_region_length();
3753 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3754 if (_surviving_young_words == NULL) {
3755 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3756 "Not enough space for young surv words summary.");
3757 }
3758 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3759 #ifdef ASSERT
3760 for (uint i = 0; i < array_length; ++i) {
3761 assert( _surviving_young_words[i] == 0, "memset above" );
3762 }
3763 #endif // !ASSERT
3764 }
3765
3766 void
3767 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3768 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3769 uint array_length = g1_policy()->young_cset_region_length();
3770 for (uint i = 0; i < array_length; ++i) {
3771 _surviving_young_words[i] += surv_young_words[i];
3772 }
3773 }
3774
3775 void
3776 G1CollectedHeap::cleanup_surviving_young_words() {
3777 guarantee( _surviving_young_words != NULL, "pre-condition" );
3778 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3779 _surviving_young_words = NULL;
3780 }
3781
3782 #ifdef ASSERT
3783 class VerifyCSetClosure: public HeapRegionClosure {
3784 public:
3785 bool doHeapRegion(HeapRegion* hr) {
3786 // Here we check that the CSet region's RSet is ready for parallel
3787 // iteration. The fields that we'll verify are only manipulated
3788 // when the region is part of a CSet and is collected. Afterwards,
3789 // we reset these fields when we clear the region's RSet (when the
3790 // region is freed) so they are ready when the region is
3791 // re-allocated. The only exception to this is if there's an
3792 // evacuation failure and instead of freeing the region we leave
3793 // it in the heap. In that case, we reset these fields during
3794 // evacuation failure handling.
3795 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3796
3797 // Here's a good place to add any other checks we'd like to
3798 // perform on CSet regions.
3799 return false;
3800 }
3801 };
3802 #endif // ASSERT
3803
3804 uint G1CollectedHeap::num_task_queues() const {
3805 return _task_queues->size();
3806 }
3807
3808 #if TASKQUEUE_STATS
3809 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3810 st->print_raw_cr("GC Task Stats");
3811 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3812 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3813 }
3814
3815 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3816 print_taskqueue_stats_hdr(st);
3817
3818 TaskQueueStats totals;
3819 const uint n = num_task_queues();
3820 for (uint i = 0; i < n; ++i) {
3821 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3822 totals += task_queue(i)->stats;
3823 }
3824 st->print_raw("tot "); totals.print(st); st->cr();
3825
3826 DEBUG_ONLY(totals.verify());
3827 }
3828
3829 void G1CollectedHeap::reset_taskqueue_stats() {
3830 const uint n = num_task_queues();
3831 for (uint i = 0; i < n; ++i) {
3832 task_queue(i)->stats.reset();
3833 }
3834 }
3835 #endif // TASKQUEUE_STATS
3836
3837 void G1CollectedHeap::log_gc_header() {
3838 if (!G1Log::fine()) {
3839 return;
3840 }
3841
3842 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3843
3844 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3845 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3846 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3847
3848 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3849 }
3850
3851 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3852 if (!G1Log::fine()) {
3853 return;
3854 }
3855
3856 if (G1Log::finer()) {
3857 if (evacuation_failed()) {
3858 gclog_or_tty->print(" (to-space exhausted)");
3859 }
3860 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3861 g1_policy()->phase_times()->note_gc_end();
3862 g1_policy()->phase_times()->print(pause_time_sec);
3863 g1_policy()->print_detailed_heap_transition();
3864 } else {
3865 if (evacuation_failed()) {
3866 gclog_or_tty->print("--");
3867 }
3868 g1_policy()->print_heap_transition();
3869 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3870 }
3871 gclog_or_tty->flush();
3872 }
3873
3874 void G1CollectedHeap::wait_for_root_region_scanning() {
3875 double scan_wait_start = os::elapsedTime();
3876 // We have to wait until the CM threads finish scanning the
3877 // root regions as it's the only way to ensure that all the
3878 // objects on them have been correctly scanned before we start
3879 // moving them during the GC.
3880 bool waited = _cm->root_regions()->wait_until_scan_finished();
3881 double wait_time_ms = 0.0;
3882 if (waited) {
3883 double scan_wait_end = os::elapsedTime();
3884 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3885 }
3886 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3887 }
3888
3889 bool
3890 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3891 assert_at_safepoint(true /* should_be_vm_thread */);
3892 guarantee(!is_gc_active(), "collection is not reentrant");
3893
3894 if (GC_locker::check_active_before_gc()) {
3895 return false;
3896 }
3897
3898 _gc_timer_stw->register_gc_start();
3899
3900 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3901
3902 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3903 ResourceMark rm;
3904
3905 wait_for_root_region_scanning();
3906
3907 G1Log::update_level();
3908 print_heap_before_gc();
3909 trace_heap_before_gc(_gc_tracer_stw);
3910
3911 verify_region_sets_optional();
3912 verify_dirty_young_regions();
3913
3914 // This call will decide whether this pause is an initial-mark
3915 // pause. If it is, during_initial_mark_pause() will return true
3916 // for the duration of this pause.
3917 g1_policy()->decide_on_conc_mark_initiation();
3918
3919 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3920 assert(!collector_state()->during_initial_mark_pause() ||
3921 collector_state()->gcs_are_young(), "sanity");
3922
3923 // We also do not allow mixed GCs during marking.
3924 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3925
3926 // Record whether this pause is an initial mark. When the current
3927 // thread has completed its logging output and it's safe to signal
3928 // the CM thread, the flag's value in the policy has been reset.
3929 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3930
3931 // Inner scope for scope based logging, timers, and stats collection
3932 {
3933 EvacuationInfo evacuation_info;
3934
3935 if (collector_state()->during_initial_mark_pause()) {
3936 // We are about to start a marking cycle, so we increment the
3937 // full collection counter.
3938 increment_old_marking_cycles_started();
3939 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3940 }
3941
3942 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3943
3944 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3945
3946 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3947 workers()->active_workers(),
3948 Threads::number_of_non_daemon_threads());
3949 workers()->set_active_workers(active_workers);
3950
3951 double pause_start_sec = os::elapsedTime();
3952 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
3953 log_gc_header();
3954
3955 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3956 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3957
3958 // If the secondary_free_list is not empty, append it to the
3959 // free_list. No need to wait for the cleanup operation to finish;
3960 // the region allocation code will check the secondary_free_list
3961 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3962 // set, skip this step so that the region allocation code has to
3963 // get entries from the secondary_free_list.
3964 if (!G1StressConcRegionFreeing) {
3965 append_secondary_free_list_if_not_empty_with_lock();
3966 }
3967
3968 assert(check_young_list_well_formed(), "young list should be well formed");
3969
3970 // Don't dynamically change the number of GC threads this early. A value of
3971 // 0 is used to indicate serial work. When parallel work is done,
3972 // it will be set.
3973
3974 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3975 IsGCActiveMark x;
3976
3977 gc_prologue(false);
3978 increment_total_collections(false /* full gc */);
3979 increment_gc_time_stamp();
3980
3981 verify_before_gc();
3982
3983 check_bitmaps("GC Start");
3984
3985 COMPILER2_PRESENT(DerivedPointerTable::clear());
3986
3987 // Please see comment in g1CollectedHeap.hpp and
3988 // G1CollectedHeap::ref_processing_init() to see how
3989 // reference processing currently works in G1.
3990
3991 // Enable discovery in the STW reference processor
3992 ref_processor_stw()->enable_discovery();
3993
3994 {
3995 // We want to temporarily turn off discovery by the
3996 // CM ref processor, if necessary, and turn it back on
3997 // on again later if we do. Using a scoped
3998 // NoRefDiscovery object will do this.
3999 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4000
4001 // Forget the current alloc region (we might even choose it to be part
4002 // of the collection set!).
4003 _allocator->release_mutator_alloc_region();
4004
4005 // We should call this after we retire the mutator alloc
4006 // region(s) so that all the ALLOC / RETIRE events are generated
4007 // before the start GC event.
4008 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4009
4010 // This timing is only used by the ergonomics to handle our pause target.
4011 // It is unclear why this should not include the full pause. We will
4012 // investigate this in CR 7178365.
4013 //
4014 // Preserving the old comment here if that helps the investigation:
4015 //
4016 // The elapsed time induced by the start time below deliberately elides
4017 // the possible verification above.
4018 double sample_start_time_sec = os::elapsedTime();
4019
4020 #if YOUNG_LIST_VERBOSE
4021 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4022 _young_list->print();
4023 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4024 #endif // YOUNG_LIST_VERBOSE
4025
4026 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4027
4028 #if YOUNG_LIST_VERBOSE
4029 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4030 _young_list->print();
4031 #endif // YOUNG_LIST_VERBOSE
4032
4033 if (collector_state()->during_initial_mark_pause()) {
4034 concurrent_mark()->checkpointRootsInitialPre();
4035 }
4036
4037 #if YOUNG_LIST_VERBOSE
4038 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4039 _young_list->print();
4040 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4041 #endif // YOUNG_LIST_VERBOSE
4042
4043 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4044
4045 register_humongous_regions_with_cset();
4046
4047 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4048
4049 _cm->note_start_of_gc();
4050 // We call this after finalize_cset() to
4051 // ensure that the CSet has been finalized.
4052 _cm->verify_no_cset_oops();
4053
4054 if (_hr_printer.is_active()) {
4055 HeapRegion* hr = g1_policy()->collection_set();
4056 while (hr != NULL) {
4057 _hr_printer.cset(hr);
4058 hr = hr->next_in_collection_set();
4059 }
4060 }
4061
4062 #ifdef ASSERT
4063 VerifyCSetClosure cl;
4064 collection_set_iterate(&cl);
4065 #endif // ASSERT
4066
4067 setup_surviving_young_words();
4068
4069 // Initialize the GC alloc regions.
4070 _allocator->init_gc_alloc_regions(evacuation_info);
4071
4072 // Actually do the work...
4073 evacuate_collection_set(evacuation_info);
4074
4075 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4076
4077 eagerly_reclaim_humongous_regions();
4078
4079 g1_policy()->clear_collection_set();
4080
4081 cleanup_surviving_young_words();
4082
4083 // Start a new incremental collection set for the next pause.
4084 g1_policy()->start_incremental_cset_building();
4085
4086 clear_cset_fast_test();
4087
4088 _young_list->reset_sampled_info();
4089
4090 // Don't check the whole heap at this point as the
4091 // GC alloc regions from this pause have been tagged
4092 // as survivors and moved on to the survivor list.
4093 // Survivor regions will fail the !is_young() check.
4094 assert(check_young_list_empty(false /* check_heap */),
4095 "young list should be empty");
4096
4097 #if YOUNG_LIST_VERBOSE
4098 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4099 _young_list->print();
4100 #endif // YOUNG_LIST_VERBOSE
4101
4102 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4103 _young_list->first_survivor_region(),
4104 _young_list->last_survivor_region());
4105
4106 _young_list->reset_auxilary_lists();
4107
4108 if (evacuation_failed()) {
4109 _allocator->set_used(recalculate_used());
4110 if (_archive_allocator != NULL) {
4111 _archive_allocator->clear_used();
4112 }
4113 for (uint i = 0; i < ParallelGCThreads; i++) {
4114 if (_evacuation_failed_info_array[i].has_failed()) {
4115 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4116 }
4117 }
4118 } else {
4119 // The "used" of the the collection set have already been subtracted
4120 // when they were freed. Add in the bytes evacuated.
4121 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4122 }
4123
4124 if (collector_state()->during_initial_mark_pause()) {
4125 // We have to do this before we notify the CM threads that
4126 // they can start working to make sure that all the
4127 // appropriate initialization is done on the CM object.
4128 concurrent_mark()->checkpointRootsInitialPost();
4129 collector_state()->set_mark_in_progress(true);
4130 // Note that we don't actually trigger the CM thread at
4131 // this point. We do that later when we're sure that
4132 // the current thread has completed its logging output.
4133 }
4134
4135 allocate_dummy_regions();
4136
4137 #if YOUNG_LIST_VERBOSE
4138 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4139 _young_list->print();
4140 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4141 #endif // YOUNG_LIST_VERBOSE
4142
4143 _allocator->init_mutator_alloc_region();
4144
4145 {
4146 size_t expand_bytes = g1_policy()->expansion_amount();
4147 if (expand_bytes > 0) {
4148 size_t bytes_before = capacity();
4149 // No need for an ergo verbose message here,
4150 // expansion_amount() does this when it returns a value > 0.
4151 if (!expand(expand_bytes)) {
4152 // We failed to expand the heap. Cannot do anything about it.
4153 }
4154 }
4155 }
4156
4157 // We redo the verification but now wrt to the new CSet which
4158 // has just got initialized after the previous CSet was freed.
4159 _cm->verify_no_cset_oops();
4160 _cm->note_end_of_gc();
4161
4162 // This timing is only used by the ergonomics to handle our pause target.
4163 // It is unclear why this should not include the full pause. We will
4164 // investigate this in CR 7178365.
4165 double sample_end_time_sec = os::elapsedTime();
4166 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4167 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4168
4169 MemoryService::track_memory_usage();
4170
4171 // In prepare_for_verify() below we'll need to scan the deferred
4172 // update buffers to bring the RSets up-to-date if
4173 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4174 // the update buffers we'll probably need to scan cards on the
4175 // regions we just allocated to (i.e., the GC alloc
4176 // regions). However, during the last GC we called
4177 // set_saved_mark() on all the GC alloc regions, so card
4178 // scanning might skip the [saved_mark_word()...top()] area of
4179 // those regions (i.e., the area we allocated objects into
4180 // during the last GC). But it shouldn't. Given that
4181 // saved_mark_word() is conditional on whether the GC time stamp
4182 // on the region is current or not, by incrementing the GC time
4183 // stamp here we invalidate all the GC time stamps on all the
4184 // regions and saved_mark_word() will simply return top() for
4185 // all the regions. This is a nicer way of ensuring this rather
4186 // than iterating over the regions and fixing them. In fact, the
4187 // GC time stamp increment here also ensures that
4188 // saved_mark_word() will return top() between pauses, i.e.,
4189 // during concurrent refinement. So we don't need the
4190 // is_gc_active() check to decided which top to use when
4191 // scanning cards (see CR 7039627).
4192 increment_gc_time_stamp();
4193
4194 verify_after_gc();
4195 check_bitmaps("GC End");
4196
4197 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4198 ref_processor_stw()->verify_no_references_recorded();
4199
4200 // CM reference discovery will be re-enabled if necessary.
4201 }
4202
4203 // We should do this after we potentially expand the heap so
4204 // that all the COMMIT events are generated before the end GC
4205 // event, and after we retire the GC alloc regions so that all
4206 // RETIRE events are generated before the end GC event.
4207 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4208
4209 #ifdef TRACESPINNING
4210 ParallelTaskTerminator::print_termination_counts();
4211 #endif
4212
4213 gc_epilogue(false);
4214 }
4215
4216 // Print the remainder of the GC log output.
4217 log_gc_footer(os::elapsedTime() - pause_start_sec);
4218
4219 // It is not yet to safe to tell the concurrent mark to
4220 // start as we have some optional output below. We don't want the
4221 // output from the concurrent mark thread interfering with this
4222 // logging output either.
4223
4224 _hrm.verify_optional();
4225 verify_region_sets_optional();
4226
4227 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4228 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4229
4230 print_heap_after_gc();
4231 trace_heap_after_gc(_gc_tracer_stw);
4232
4233 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4234 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4235 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4236 // before any GC notifications are raised.
4237 g1mm()->update_sizes();
4238
4239 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4240 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4241 _gc_timer_stw->register_gc_end();
4242 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4243 }
4244 // It should now be safe to tell the concurrent mark thread to start
4245 // without its logging output interfering with the logging output
4246 // that came from the pause.
4247
4248 if (should_start_conc_mark) {
4249 // CAUTION: after the doConcurrentMark() call below,
4250 // the concurrent marking thread(s) could be running
4251 // concurrently with us. Make sure that anything after
4252 // this point does not assume that we are the only GC thread
4253 // running. Note: of course, the actual marking work will
4254 // not start until the safepoint itself is released in
4255 // SuspendibleThreadSet::desynchronize().
4256 doConcurrentMark();
4257 }
4258
4259 return true;
4260 }
4261
4262 void G1CollectedHeap::remove_self_forwarding_pointers() {
4263 double remove_self_forwards_start = os::elapsedTime();
4264
4265 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4266 workers()->run_task(&rsfp_task);
4267
4268 // Now restore saved marks, if any.
4269 for (uint i = 0; i < ParallelGCThreads; i++) {
4270 OopAndMarkOopStack& cur = _preserved_objs[i];
4271 while (!cur.is_empty()) {
4272 OopAndMarkOop elem = cur.pop();
4273 elem.set_mark();
4274 }
4275 cur.clear(true);
4276 }
4277
4278 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4279 }
4280
4281 void G1CollectedHeap::preserve_mark_during_evac_failure(uint queue_num, oop obj, markOop m) {
4282 if (!_evacuation_failed) {
4283 _evacuation_failed = true;
4284 }
4285
4286 _evacuation_failed_info_array[queue_num].register_copy_failure(obj->size());
4287
4288 // We want to call the "for_promotion_failure" version only in the
4289 // case of a promotion failure.
4290 if (m->must_be_preserved_for_promotion_failure(obj)) {
4291 OopAndMarkOop elem(obj, m);
4292 _preserved_objs[queue_num].push(elem);
4293 }
4294 }
4295
4296 void G1ParCopyHelper::mark_object(oop obj) {
4297 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4298
4299 // We know that the object is not moving so it's safe to read its size.
4300 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4301 }
4302
4303 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4304 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4305 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4306 assert(from_obj != to_obj, "should not be self-forwarded");
4307
4308 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4309 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4310
4311 // The object might be in the process of being copied by another
4312 // worker so we cannot trust that its to-space image is
4313 // well-formed. So we have to read its size from its from-space
4314 // image which we know should not be changing.
4315 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4316 }
4317
4318 template <class T>
4319 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4320 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4321 _scanned_klass->record_modified_oops();
4322 }
4323 }
4324
4325 template <G1Barrier barrier, G1Mark do_mark_object>
4326 template <class T>
4327 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4328 T heap_oop = oopDesc::load_heap_oop(p);
4329
4330 if (oopDesc::is_null(heap_oop)) {
4331 return;
4332 }
4333
4334 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4335
4336 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4337
4338 const InCSetState state = _g1->in_cset_state(obj);
4339 if (state.is_in_cset()) {
4340 oop forwardee;
4341 markOop m = obj->mark();
4342 if (m->is_marked()) {
4343 forwardee = (oop) m->decode_pointer();
4344 } else {
4345 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4346 }
4347 assert(forwardee != NULL, "forwardee should not be NULL");
4348 oopDesc::encode_store_heap_oop(p, forwardee);
4349 if (do_mark_object != G1MarkNone && forwardee != obj) {
4350 // If the object is self-forwarded we don't need to explicitly
4351 // mark it, the evacuation failure protocol will do so.
4352 mark_forwarded_object(obj, forwardee);
4353 }
4354
4355 if (barrier == G1BarrierKlass) {
4356 do_klass_barrier(p, forwardee);
4357 }
4358 } else {
4359 if (state.is_humongous()) {
4360 _g1->set_humongous_is_live(obj);
4361 }
4362 // The object is not in collection set. If we're a root scanning
4363 // closure during an initial mark pause then attempt to mark the object.
4364 if (do_mark_object == G1MarkFromRoot) {
4365 mark_object(obj);
4366 }
4367 }
4368 }
4369
4370 class G1ParEvacuateFollowersClosure : public VoidClosure {
4371 protected:
4372 G1CollectedHeap* _g1h;
4373 G1ParScanThreadState* _par_scan_state;
4374 RefToScanQueueSet* _queues;
4375 ParallelTaskTerminator* _terminator;
4376
4377 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4378 RefToScanQueueSet* queues() { return _queues; }
4379 ParallelTaskTerminator* terminator() { return _terminator; }
4380
4381 public:
4382 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4383 G1ParScanThreadState* par_scan_state,
4384 RefToScanQueueSet* queues,
4385 ParallelTaskTerminator* terminator)
4386 : _g1h(g1h), _par_scan_state(par_scan_state),
4387 _queues(queues), _terminator(terminator) {}
4388
4389 void do_void();
4390
4391 private:
4392 inline bool offer_termination();
4393 };
4394
4395 bool G1ParEvacuateFollowersClosure::offer_termination() {
4396 G1ParScanThreadState* const pss = par_scan_state();
4397 pss->start_term_time();
4398 const bool res = terminator()->offer_termination();
4399 pss->end_term_time();
4400 return res;
4401 }
4402
4403 void G1ParEvacuateFollowersClosure::do_void() {
4404 G1ParScanThreadState* const pss = par_scan_state();
4405 pss->trim_queue();
4406 do {
4407 pss->steal_and_trim_queue(queues());
4408 } while (!offer_termination());
4409 }
4410
4411 class G1KlassScanClosure : public KlassClosure {
4412 G1ParCopyHelper* _closure;
4413 bool _process_only_dirty;
4414 int _count;
4415 public:
4416 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4417 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4418 void do_klass(Klass* klass) {
4419 // If the klass has not been dirtied we know that there's
4420 // no references into the young gen and we can skip it.
4421 if (!_process_only_dirty || klass->has_modified_oops()) {
4422 // Clean the klass since we're going to scavenge all the metadata.
4423 klass->clear_modified_oops();
4424
4425 // Tell the closure that this klass is the Klass to scavenge
4426 // and is the one to dirty if oops are left pointing into the young gen.
4427 _closure->set_scanned_klass(klass);
4428
4429 klass->oops_do(_closure);
4430
4431 _closure->set_scanned_klass(NULL);
4432 }
4433 _count++;
4434 }
4435 };
4436
4437 class G1ParTask : public AbstractGangTask {
4438 protected:
4439 G1CollectedHeap* _g1h;
4440 RefToScanQueueSet *_queues;
4441 G1RootProcessor* _root_processor;
4442 ParallelTaskTerminator _terminator;
4443 uint _n_workers;
4444
4445 Mutex _stats_lock;
4446 Mutex* stats_lock() { return &_stats_lock; }
4447
4448 public:
4449 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4450 : AbstractGangTask("G1 collection"),
4451 _g1h(g1h),
4452 _queues(task_queues),
4453 _root_processor(root_processor),
4454 _terminator(n_workers, _queues),
4455 _n_workers(n_workers),
4456 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4457 {}
4458
4459 RefToScanQueueSet* queues() { return _queues; }
4460
4461 RefToScanQueue *work_queue(int i) {
4462 return queues()->queue(i);
4463 }
4464
4465 ParallelTaskTerminator* terminator() { return &_terminator; }
4466
4467 // Helps out with CLD processing.
4468 //
4469 // During InitialMark we need to:
4470 // 1) Scavenge all CLDs for the young GC.
4471 // 2) Mark all objects directly reachable from strong CLDs.
4472 template <G1Mark do_mark_object>
4473 class G1CLDClosure : public CLDClosure {
4474 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4475 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4476 G1KlassScanClosure _klass_in_cld_closure;
4477 bool _claim;
4478
4479 public:
4480 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4481 bool only_young, bool claim)
4482 : _oop_closure(oop_closure),
4483 _oop_in_klass_closure(oop_closure->g1(),
4484 oop_closure->pss(),
4485 oop_closure->rp()),
4486 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4487 _claim(claim) {
4488
4489 }
4490
4491 void do_cld(ClassLoaderData* cld) {
4492 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4493 }
4494 };
4495
4496 void work(uint worker_id) {
4497 if (worker_id >= _n_workers) return; // no work needed this round
4498
4499 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4500
4501 {
4502 ResourceMark rm;
4503 HandleMark hm;
4504
4505 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4506
4507 G1ParScanThreadState pss(_g1h, worker_id, rp);
4508
4509 bool only_young = _g1h->collector_state()->gcs_are_young();
4510
4511 // Non-IM young GC.
4512 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4513 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4514 only_young, // Only process dirty klasses.
4515 false); // No need to claim CLDs.
4516 // IM young GC.
4517 // Strong roots closures.
4518 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4519 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4520 false, // Process all klasses.
4521 true); // Need to claim CLDs.
4522 // Weak roots closures.
4523 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4524 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4525 false, // Process all klasses.
4526 true); // Need to claim CLDs.
4527
4528 OopClosure* strong_root_cl;
4529 OopClosure* weak_root_cl;
4530 CLDClosure* strong_cld_cl;
4531 CLDClosure* weak_cld_cl;
4532
4533 bool trace_metadata = false;
4534
4535 if (_g1h->collector_state()->during_initial_mark_pause()) {
4536 // We also need to mark copied objects.
4537 strong_root_cl = &scan_mark_root_cl;
4538 strong_cld_cl = &scan_mark_cld_cl;
4539 if (ClassUnloadingWithConcurrentMark) {
4540 weak_root_cl = &scan_mark_weak_root_cl;
4541 weak_cld_cl = &scan_mark_weak_cld_cl;
4542 trace_metadata = true;
4543 } else {
4544 weak_root_cl = &scan_mark_root_cl;
4545 weak_cld_cl = &scan_mark_cld_cl;
4546 }
4547 } else {
4548 strong_root_cl = &scan_only_root_cl;
4549 weak_root_cl = &scan_only_root_cl;
4550 strong_cld_cl = &scan_only_cld_cl;
4551 weak_cld_cl = &scan_only_cld_cl;
4552 }
4553
4554 pss.start_strong_roots();
4555
4556 _root_processor->evacuate_roots(strong_root_cl,
4557 weak_root_cl,
4558 strong_cld_cl,
4559 weak_cld_cl,
4560 trace_metadata,
4561 worker_id);
4562
4563 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4564 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4565 weak_root_cl,
4566 worker_id);
4567 pss.end_strong_roots();
4568
4569 {
4570 double start = os::elapsedTime();
4571 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4572 evac.do_void();
4573 double elapsed_sec = os::elapsedTime() - start;
4574 double term_sec = pss.term_time();
4575 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4576 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4577 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4578 }
4579 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4580 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4581
4582 if (PrintTerminationStats) {
4583 MutexLocker x(stats_lock());
4584 pss.print_termination_stats(worker_id);
4585 }
4586
4587 assert(pss.queue_is_empty(), "should be empty");
4588
4589 // Close the inner scope so that the ResourceMark and HandleMark
4590 // destructors are executed here and are included as part of the
4591 // "GC Worker Time".
4592 }
4593 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4594 }
4595 };
4596
4597 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4598 private:
4599 BoolObjectClosure* _is_alive;
4600 int _initial_string_table_size;
4601 int _initial_symbol_table_size;
4602
4603 bool _process_strings;
4604 int _strings_processed;
4605 int _strings_removed;
4606
4607 bool _process_symbols;
4608 int _symbols_processed;
4609 int _symbols_removed;
4610
4611 public:
4612 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4613 AbstractGangTask("String/Symbol Unlinking"),
4614 _is_alive(is_alive),
4615 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4616 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4617
4618 _initial_string_table_size = StringTable::the_table()->table_size();
4619 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4620 if (process_strings) {
4621 StringTable::clear_parallel_claimed_index();
4622 }
4623 if (process_symbols) {
4624 SymbolTable::clear_parallel_claimed_index();
4625 }
4626 }
4627
4628 ~G1StringSymbolTableUnlinkTask() {
4629 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4630 err_msg("claim value %d after unlink less than initial string table size %d",
4631 StringTable::parallel_claimed_index(), _initial_string_table_size));
4632 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4633 err_msg("claim value %d after unlink less than initial symbol table size %d",
4634 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4635
4636 if (G1TraceStringSymbolTableScrubbing) {
4637 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4638 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4639 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4640 strings_processed(), strings_removed(),
4641 symbols_processed(), symbols_removed());
4642 }
4643 }
4644
4645 void work(uint worker_id) {
4646 int strings_processed = 0;
4647 int strings_removed = 0;
4648 int symbols_processed = 0;
4649 int symbols_removed = 0;
4650 if (_process_strings) {
4651 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4652 Atomic::add(strings_processed, &_strings_processed);
4653 Atomic::add(strings_removed, &_strings_removed);
4654 }
4655 if (_process_symbols) {
4656 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4657 Atomic::add(symbols_processed, &_symbols_processed);
4658 Atomic::add(symbols_removed, &_symbols_removed);
4659 }
4660 }
4661
4662 size_t strings_processed() const { return (size_t)_strings_processed; }
4663 size_t strings_removed() const { return (size_t)_strings_removed; }
4664
4665 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4666 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4667 };
4668
4669 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4670 private:
4671 static Monitor* _lock;
4672
4673 BoolObjectClosure* const _is_alive;
4674 const bool _unloading_occurred;
4675 const uint _num_workers;
4676
4677 // Variables used to claim nmethods.
4678 nmethod* _first_nmethod;
4679 volatile nmethod* _claimed_nmethod;
4680
4681 // The list of nmethods that need to be processed by the second pass.
4682 volatile nmethod* _postponed_list;
4683 volatile uint _num_entered_barrier;
4684
4685 public:
4686 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4687 _is_alive(is_alive),
4688 _unloading_occurred(unloading_occurred),
4689 _num_workers(num_workers),
4690 _first_nmethod(NULL),
4691 _claimed_nmethod(NULL),
4692 _postponed_list(NULL),
4693 _num_entered_barrier(0)
4694 {
4695 nmethod::increase_unloading_clock();
4696 // Get first alive nmethod
4697 NMethodIterator iter = NMethodIterator();
4698 if(iter.next_alive()) {
4699 _first_nmethod = iter.method();
4700 }
4701 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4702 }
4703
4704 ~G1CodeCacheUnloadingTask() {
4705 CodeCache::verify_clean_inline_caches();
4706
4707 CodeCache::set_needs_cache_clean(false);
4708 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4709
4710 CodeCache::verify_icholder_relocations();
4711 }
4712
4713 private:
4714 void add_to_postponed_list(nmethod* nm) {
4715 nmethod* old;
4716 do {
4717 old = (nmethod*)_postponed_list;
4718 nm->set_unloading_next(old);
4719 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4720 }
4721
4722 void clean_nmethod(nmethod* nm) {
4723 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4724
4725 if (postponed) {
4726 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4727 add_to_postponed_list(nm);
4728 }
4729
4730 // Mark that this thread has been cleaned/unloaded.
4731 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4732 nm->set_unloading_clock(nmethod::global_unloading_clock());
4733 }
4734
4735 void clean_nmethod_postponed(nmethod* nm) {
4736 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4737 }
4738
4739 static const int MaxClaimNmethods = 16;
4740
4741 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4742 nmethod* first;
4743 NMethodIterator last;
4744
4745 do {
4746 *num_claimed_nmethods = 0;
4747
4748 first = (nmethod*)_claimed_nmethod;
4749 last = NMethodIterator(first);
4750
4751 if (first != NULL) {
4752
4753 for (int i = 0; i < MaxClaimNmethods; i++) {
4754 if (!last.next_alive()) {
4755 break;
4756 }
4757 claimed_nmethods[i] = last.method();
4758 (*num_claimed_nmethods)++;
4759 }
4760 }
4761
4762 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4763 }
4764
4765 nmethod* claim_postponed_nmethod() {
4766 nmethod* claim;
4767 nmethod* next;
4768
4769 do {
4770 claim = (nmethod*)_postponed_list;
4771 if (claim == NULL) {
4772 return NULL;
4773 }
4774
4775 next = claim->unloading_next();
4776
4777 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4778
4779 return claim;
4780 }
4781
4782 public:
4783 // Mark that we're done with the first pass of nmethod cleaning.
4784 void barrier_mark(uint worker_id) {
4785 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4786 _num_entered_barrier++;
4787 if (_num_entered_barrier == _num_workers) {
4788 ml.notify_all();
4789 }
4790 }
4791
4792 // See if we have to wait for the other workers to
4793 // finish their first-pass nmethod cleaning work.
4794 void barrier_wait(uint worker_id) {
4795 if (_num_entered_barrier < _num_workers) {
4796 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4797 while (_num_entered_barrier < _num_workers) {
4798 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4799 }
4800 }
4801 }
4802
4803 // Cleaning and unloading of nmethods. Some work has to be postponed
4804 // to the second pass, when we know which nmethods survive.
4805 void work_first_pass(uint worker_id) {
4806 // The first nmethods is claimed by the first worker.
4807 if (worker_id == 0 && _first_nmethod != NULL) {
4808 clean_nmethod(_first_nmethod);
4809 _first_nmethod = NULL;
4810 }
4811
4812 int num_claimed_nmethods;
4813 nmethod* claimed_nmethods[MaxClaimNmethods];
4814
4815 while (true) {
4816 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4817
4818 if (num_claimed_nmethods == 0) {
4819 break;
4820 }
4821
4822 for (int i = 0; i < num_claimed_nmethods; i++) {
4823 clean_nmethod(claimed_nmethods[i]);
4824 }
4825 }
4826 }
4827
4828 void work_second_pass(uint worker_id) {
4829 nmethod* nm;
4830 // Take care of postponed nmethods.
4831 while ((nm = claim_postponed_nmethod()) != NULL) {
4832 clean_nmethod_postponed(nm);
4833 }
4834 }
4835 };
4836
4837 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4838
4839 class G1KlassCleaningTask : public StackObj {
4840 BoolObjectClosure* _is_alive;
4841 volatile jint _clean_klass_tree_claimed;
4842 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4843
4844 public:
4845 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4846 _is_alive(is_alive),
4847 _clean_klass_tree_claimed(0),
4848 _klass_iterator() {
4849 }
4850
4851 private:
4852 bool claim_clean_klass_tree_task() {
4853 if (_clean_klass_tree_claimed) {
4854 return false;
4855 }
4856
4857 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4858 }
4859
4860 InstanceKlass* claim_next_klass() {
4861 Klass* klass;
4862 do {
4863 klass =_klass_iterator.next_klass();
4864 } while (klass != NULL && !klass->oop_is_instance());
4865
4866 return (InstanceKlass*)klass;
4867 }
4868
4869 public:
4870
4871 void clean_klass(InstanceKlass* ik) {
4872 ik->clean_implementors_list(_is_alive);
4873 ik->clean_method_data(_is_alive);
4874
4875 // G1 specific cleanup work that has
4876 // been moved here to be done in parallel.
4877 ik->clean_dependent_nmethods();
4878 }
4879
4880 void work() {
4881 ResourceMark rm;
4882
4883 // One worker will clean the subklass/sibling klass tree.
4884 if (claim_clean_klass_tree_task()) {
4885 Klass::clean_subklass_tree(_is_alive);
4886 }
4887
4888 // All workers will help cleaning the classes,
4889 InstanceKlass* klass;
4890 while ((klass = claim_next_klass()) != NULL) {
4891 clean_klass(klass);
4892 }
4893 }
4894 };
4895
4896 // To minimize the remark pause times, the tasks below are done in parallel.
4897 class G1ParallelCleaningTask : public AbstractGangTask {
4898 private:
4899 G1StringSymbolTableUnlinkTask _string_symbol_task;
4900 G1CodeCacheUnloadingTask _code_cache_task;
4901 G1KlassCleaningTask _klass_cleaning_task;
4902
4903 public:
4904 // The constructor is run in the VMThread.
4905 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4906 AbstractGangTask("Parallel Cleaning"),
4907 _string_symbol_task(is_alive, process_strings, process_symbols),
4908 _code_cache_task(num_workers, is_alive, unloading_occurred),
4909 _klass_cleaning_task(is_alive) {
4910 }
4911
4912 // The parallel work done by all worker threads.
4913 void work(uint worker_id) {
4914 // Do first pass of code cache cleaning.
4915 _code_cache_task.work_first_pass(worker_id);
4916
4917 // Let the threads mark that the first pass is done.
4918 _code_cache_task.barrier_mark(worker_id);
4919
4920 // Clean the Strings and Symbols.
4921 _string_symbol_task.work(worker_id);
4922
4923 // Wait for all workers to finish the first code cache cleaning pass.
4924 _code_cache_task.barrier_wait(worker_id);
4925
4926 // Do the second code cache cleaning work, which realize on
4927 // the liveness information gathered during the first pass.
4928 _code_cache_task.work_second_pass(worker_id);
4929
4930 // Clean all klasses that were not unloaded.
4931 _klass_cleaning_task.work();
4932 }
4933 };
4934
4935
4936 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4937 bool process_strings,
4938 bool process_symbols,
4939 bool class_unloading_occurred) {
4940 uint n_workers = workers()->active_workers();
4941
4942 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4943 n_workers, class_unloading_occurred);
4944 workers()->run_task(&g1_unlink_task);
4945 }
4946
4947 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4948 bool process_strings, bool process_symbols) {
4949 {
4950 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4951 workers()->run_task(&g1_unlink_task);
4952 }
4953
4954 if (G1StringDedup::is_enabled()) {
4955 G1StringDedup::unlink(is_alive);
4956 }
4957 }
4958
4959 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4960 private:
4961 DirtyCardQueueSet* _queue;
4962 public:
4963 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4964
4965 virtual void work(uint worker_id) {
4966 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4967 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4968
4969 RedirtyLoggedCardTableEntryClosure cl;
4970 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4971
4972 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4973 }
4974 };
4975
4976 void G1CollectedHeap::redirty_logged_cards() {
4977 double redirty_logged_cards_start = os::elapsedTime();
4978
4979 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4980 dirty_card_queue_set().reset_for_par_iteration();
4981 workers()->run_task(&redirty_task);
4982
4983 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4984 dcq.merge_bufferlists(&dirty_card_queue_set());
4985 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4986
4987 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4988 }
4989
4990 // Weak Reference Processing support
4991
4992 // An always "is_alive" closure that is used to preserve referents.
4993 // If the object is non-null then it's alive. Used in the preservation
4994 // of referent objects that are pointed to by reference objects
4995 // discovered by the CM ref processor.
4996 class G1AlwaysAliveClosure: public BoolObjectClosure {
4997 G1CollectedHeap* _g1;
4998 public:
4999 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5000 bool do_object_b(oop p) {
5001 if (p != NULL) {
5002 return true;
5003 }
5004 return false;
5005 }
5006 };
5007
5008 bool G1STWIsAliveClosure::do_object_b(oop p) {
5009 // An object is reachable if it is outside the collection set,
5010 // or is inside and copied.
5011 return !_g1->obj_in_cs(p) || p->is_forwarded();
5012 }
5013
5014 // Non Copying Keep Alive closure
5015 class G1KeepAliveClosure: public OopClosure {
5016 G1CollectedHeap* _g1;
5017 public:
5018 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5019 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5020 void do_oop(oop* p) {
5021 oop obj = *p;
5022 assert(obj != NULL, "the caller should have filtered out NULL values");
5023
5024 const InCSetState cset_state = _g1->in_cset_state(obj);
5025 if (!cset_state.is_in_cset_or_humongous()) {
5026 return;
5027 }
5028 if (cset_state.is_in_cset()) {
5029 assert( obj->is_forwarded(), "invariant" );
5030 *p = obj->forwardee();
5031 } else {
5032 assert(!obj->is_forwarded(), "invariant" );
5033 assert(cset_state.is_humongous(),
5034 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5035 _g1->set_humongous_is_live(obj);
5036 }
5037 }
5038 };
5039
5040 // Copying Keep Alive closure - can be called from both
5041 // serial and parallel code as long as different worker
5042 // threads utilize different G1ParScanThreadState instances
5043 // and different queues.
5044
5045 class G1CopyingKeepAliveClosure: public OopClosure {
5046 G1CollectedHeap* _g1h;
5047 OopClosure* _copy_non_heap_obj_cl;
5048 G1ParScanThreadState* _par_scan_state;
5049
5050 public:
5051 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5052 OopClosure* non_heap_obj_cl,
5053 G1ParScanThreadState* pss):
5054 _g1h(g1h),
5055 _copy_non_heap_obj_cl(non_heap_obj_cl),
5056 _par_scan_state(pss)
5057 {}
5058
5059 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5060 virtual void do_oop( oop* p) { do_oop_work(p); }
5061
5062 template <class T> void do_oop_work(T* p) {
5063 oop obj = oopDesc::load_decode_heap_oop(p);
5064
5065 if (_g1h->is_in_cset_or_humongous(obj)) {
5066 // If the referent object has been forwarded (either copied
5067 // to a new location or to itself in the event of an
5068 // evacuation failure) then we need to update the reference
5069 // field and, if both reference and referent are in the G1
5070 // heap, update the RSet for the referent.
5071 //
5072 // If the referent has not been forwarded then we have to keep
5073 // it alive by policy. Therefore we have copy the referent.
5074 //
5075 // If the reference field is in the G1 heap then we can push
5076 // on the PSS queue. When the queue is drained (after each
5077 // phase of reference processing) the object and it's followers
5078 // will be copied, the reference field set to point to the
5079 // new location, and the RSet updated. Otherwise we need to
5080 // use the the non-heap or metadata closures directly to copy
5081 // the referent object and update the pointer, while avoiding
5082 // updating the RSet.
5083
5084 if (_g1h->is_in_g1_reserved(p)) {
5085 _par_scan_state->push_on_queue(p);
5086 } else {
5087 assert(!Metaspace::contains((const void*)p),
5088 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5089 _copy_non_heap_obj_cl->do_oop(p);
5090 }
5091 }
5092 }
5093 };
5094
5095 // Serial drain queue closure. Called as the 'complete_gc'
5096 // closure for each discovered list in some of the
5097 // reference processing phases.
5098
5099 class G1STWDrainQueueClosure: public VoidClosure {
5100 protected:
5101 G1CollectedHeap* _g1h;
5102 G1ParScanThreadState* _par_scan_state;
5103
5104 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5105
5106 public:
5107 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5108 _g1h(g1h),
5109 _par_scan_state(pss)
5110 { }
5111
5112 void do_void() {
5113 G1ParScanThreadState* const pss = par_scan_state();
5114 pss->trim_queue();
5115 }
5116 };
5117
5118 // Parallel Reference Processing closures
5119
5120 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5121 // processing during G1 evacuation pauses.
5122
5123 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5124 private:
5125 G1CollectedHeap* _g1h;
5126 RefToScanQueueSet* _queues;
5127 FlexibleWorkGang* _workers;
5128 uint _active_workers;
5129
5130 public:
5131 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5132 FlexibleWorkGang* workers,
5133 RefToScanQueueSet *task_queues,
5134 uint n_workers) :
5135 _g1h(g1h),
5136 _queues(task_queues),
5137 _workers(workers),
5138 _active_workers(n_workers)
5139 {
5140 assert(n_workers > 0, "shouldn't call this otherwise");
5141 }
5142
5143 // Executes the given task using concurrent marking worker threads.
5144 virtual void execute(ProcessTask& task);
5145 virtual void execute(EnqueueTask& task);
5146 };
5147
5148 // Gang task for possibly parallel reference processing
5149
5150 class G1STWRefProcTaskProxy: public AbstractGangTask {
5151 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5152 ProcessTask& _proc_task;
5153 G1CollectedHeap* _g1h;
5154 RefToScanQueueSet *_task_queues;
5155 ParallelTaskTerminator* _terminator;
5156
5157 public:
5158 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5159 G1CollectedHeap* g1h,
5160 RefToScanQueueSet *task_queues,
5161 ParallelTaskTerminator* terminator) :
5162 AbstractGangTask("Process reference objects in parallel"),
5163 _proc_task(proc_task),
5164 _g1h(g1h),
5165 _task_queues(task_queues),
5166 _terminator(terminator)
5167 {}
5168
5169 virtual void work(uint worker_id) {
5170 // The reference processing task executed by a single worker.
5171 ResourceMark rm;
5172 HandleMark hm;
5173
5174 G1STWIsAliveClosure is_alive(_g1h);
5175
5176 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5177
5178 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5179
5180 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5181
5182 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5183
5184 if (_g1h->collector_state()->during_initial_mark_pause()) {
5185 // We also need to mark copied objects.
5186 copy_non_heap_cl = ©_mark_non_heap_cl;
5187 }
5188
5189 // Keep alive closure.
5190 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5191
5192 // Complete GC closure
5193 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5194
5195 // Call the reference processing task's work routine.
5196 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5197
5198 // Note we cannot assert that the refs array is empty here as not all
5199 // of the processing tasks (specifically phase2 - pp2_work) execute
5200 // the complete_gc closure (which ordinarily would drain the queue) so
5201 // the queue may not be empty.
5202 }
5203 };
5204
5205 // Driver routine for parallel reference processing.
5206 // Creates an instance of the ref processing gang
5207 // task and has the worker threads execute it.
5208 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5209 assert(_workers != NULL, "Need parallel worker threads.");
5210
5211 ParallelTaskTerminator terminator(_active_workers, _queues);
5212 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5213
5214 _workers->run_task(&proc_task_proxy);
5215 }
5216
5217 // Gang task for parallel reference enqueueing.
5218
5219 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5220 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5221 EnqueueTask& _enq_task;
5222
5223 public:
5224 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5225 AbstractGangTask("Enqueue reference objects in parallel"),
5226 _enq_task(enq_task)
5227 { }
5228
5229 virtual void work(uint worker_id) {
5230 _enq_task.work(worker_id);
5231 }
5232 };
5233
5234 // Driver routine for parallel reference enqueueing.
5235 // Creates an instance of the ref enqueueing gang
5236 // task and has the worker threads execute it.
5237
5238 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5239 assert(_workers != NULL, "Need parallel worker threads.");
5240
5241 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5242
5243 _workers->run_task(&enq_task_proxy);
5244 }
5245
5246 // End of weak reference support closures
5247
5248 // Abstract task used to preserve (i.e. copy) any referent objects
5249 // that are in the collection set and are pointed to by reference
5250 // objects discovered by the CM ref processor.
5251
5252 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5253 protected:
5254 G1CollectedHeap* _g1h;
5255 RefToScanQueueSet *_queues;
5256 ParallelTaskTerminator _terminator;
5257 uint _n_workers;
5258
5259 public:
5260 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5261 AbstractGangTask("ParPreserveCMReferents"),
5262 _g1h(g1h),
5263 _queues(task_queues),
5264 _terminator(workers, _queues),
5265 _n_workers(workers)
5266 { }
5267
5268 void work(uint worker_id) {
5269 ResourceMark rm;
5270 HandleMark hm;
5271
5272 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5273 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5274
5275 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5276
5277 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5278
5279 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5280
5281 if (_g1h->collector_state()->during_initial_mark_pause()) {
5282 // We also need to mark copied objects.
5283 copy_non_heap_cl = ©_mark_non_heap_cl;
5284 }
5285
5286 // Is alive closure
5287 G1AlwaysAliveClosure always_alive(_g1h);
5288
5289 // Copying keep alive closure. Applied to referent objects that need
5290 // to be copied.
5291 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5292
5293 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5294
5295 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5296 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5297
5298 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5299 // So this must be true - but assert just in case someone decides to
5300 // change the worker ids.
5301 assert(worker_id < limit, "sanity");
5302 assert(!rp->discovery_is_atomic(), "check this code");
5303
5304 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5305 for (uint idx = worker_id; idx < limit; idx += stride) {
5306 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5307
5308 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5309 while (iter.has_next()) {
5310 // Since discovery is not atomic for the CM ref processor, we
5311 // can see some null referent objects.
5312 iter.load_ptrs(DEBUG_ONLY(true));
5313 oop ref = iter.obj();
5314
5315 // This will filter nulls.
5316 if (iter.is_referent_alive()) {
5317 iter.make_referent_alive();
5318 }
5319 iter.move_to_next();
5320 }
5321 }
5322
5323 // Drain the queue - which may cause stealing
5324 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5325 drain_queue.do_void();
5326 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5327 assert(pss.queue_is_empty(), "should be");
5328 }
5329 };
5330
5331 // Weak Reference processing during an evacuation pause (part 1).
5332 void G1CollectedHeap::process_discovered_references() {
5333 double ref_proc_start = os::elapsedTime();
5334
5335 ReferenceProcessor* rp = _ref_processor_stw;
5336 assert(rp->discovery_enabled(), "should have been enabled");
5337
5338 // Any reference objects, in the collection set, that were 'discovered'
5339 // by the CM ref processor should have already been copied (either by
5340 // applying the external root copy closure to the discovered lists, or
5341 // by following an RSet entry).
5342 //
5343 // But some of the referents, that are in the collection set, that these
5344 // reference objects point to may not have been copied: the STW ref
5345 // processor would have seen that the reference object had already
5346 // been 'discovered' and would have skipped discovering the reference,
5347 // but would not have treated the reference object as a regular oop.
5348 // As a result the copy closure would not have been applied to the
5349 // referent object.
5350 //
5351 // We need to explicitly copy these referent objects - the references
5352 // will be processed at the end of remarking.
5353 //
5354 // We also need to do this copying before we process the reference
5355 // objects discovered by the STW ref processor in case one of these
5356 // referents points to another object which is also referenced by an
5357 // object discovered by the STW ref processor.
5358
5359 uint no_of_gc_workers = workers()->active_workers();
5360
5361 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5362 no_of_gc_workers,
5363 _task_queues);
5364
5365 workers()->run_task(&keep_cm_referents);
5366
5367 // Closure to test whether a referent is alive.
5368 G1STWIsAliveClosure is_alive(this);
5369
5370 // Even when parallel reference processing is enabled, the processing
5371 // of JNI refs is serial and performed serially by the current thread
5372 // rather than by a worker. The following PSS will be used for processing
5373 // JNI refs.
5374
5375 // Use only a single queue for this PSS.
5376 G1ParScanThreadState pss(this, 0, NULL);
5377 assert(pss.queue_is_empty(), "pre-condition");
5378
5379 // We do not embed a reference processor in the copying/scanning
5380 // closures while we're actually processing the discovered
5381 // reference objects.
5382
5383 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5384
5385 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5386
5387 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5388
5389 if (collector_state()->during_initial_mark_pause()) {
5390 // We also need to mark copied objects.
5391 copy_non_heap_cl = ©_mark_non_heap_cl;
5392 }
5393
5394 // Keep alive closure.
5395 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5396
5397 // Serial Complete GC closure
5398 G1STWDrainQueueClosure drain_queue(this, &pss);
5399
5400 // Setup the soft refs policy...
5401 rp->setup_policy(false);
5402
5403 ReferenceProcessorStats stats;
5404 if (!rp->processing_is_mt()) {
5405 // Serial reference processing...
5406 stats = rp->process_discovered_references(&is_alive,
5407 &keep_alive,
5408 &drain_queue,
5409 NULL,
5410 _gc_timer_stw,
5411 _gc_tracer_stw->gc_id());
5412 } else {
5413 // Parallel reference processing
5414 assert(rp->num_q() == no_of_gc_workers, "sanity");
5415 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5416
5417 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5418 stats = rp->process_discovered_references(&is_alive,
5419 &keep_alive,
5420 &drain_queue,
5421 &par_task_executor,
5422 _gc_timer_stw,
5423 _gc_tracer_stw->gc_id());
5424 }
5425
5426 _gc_tracer_stw->report_gc_reference_stats(stats);
5427
5428 // We have completed copying any necessary live referent objects.
5429 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5430
5431 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5432 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5433 }
5434
5435 // Weak Reference processing during an evacuation pause (part 2).
5436 void G1CollectedHeap::enqueue_discovered_references() {
5437 double ref_enq_start = os::elapsedTime();
5438
5439 ReferenceProcessor* rp = _ref_processor_stw;
5440 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5441
5442 // Now enqueue any remaining on the discovered lists on to
5443 // the pending list.
5444 if (!rp->processing_is_mt()) {
5445 // Serial reference processing...
5446 rp->enqueue_discovered_references();
5447 } else {
5448 // Parallel reference enqueueing
5449
5450 uint n_workers = workers()->active_workers();
5451
5452 assert(rp->num_q() == n_workers, "sanity");
5453 assert(n_workers <= rp->max_num_q(), "sanity");
5454
5455 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5456 rp->enqueue_discovered_references(&par_task_executor);
5457 }
5458
5459 rp->verify_no_references_recorded();
5460 assert(!rp->discovery_enabled(), "should have been disabled");
5461
5462 // FIXME
5463 // CM's reference processing also cleans up the string and symbol tables.
5464 // Should we do that here also? We could, but it is a serial operation
5465 // and could significantly increase the pause time.
5466
5467 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5468 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5469 }
5470
5471 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5472 _expand_heap_after_alloc_failure = true;
5473 _evacuation_failed = false;
5474
5475 // Should G1EvacuationFailureALot be in effect for this GC?
5476 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5477
5478 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5479
5480 // Disable the hot card cache.
5481 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5482 hot_card_cache->reset_hot_cache_claimed_index();
5483 hot_card_cache->set_use_cache(false);
5484
5485 const uint n_workers = workers()->active_workers();
5486
5487 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5488 double start_par_time_sec = os::elapsedTime();
5489 double end_par_time_sec;
5490
5491 {
5492 G1RootProcessor root_processor(this, n_workers);
5493 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5494 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5495 if (collector_state()->during_initial_mark_pause()) {
5496 ClassLoaderDataGraph::clear_claimed_marks();
5497 }
5498
5499 // The individual threads will set their evac-failure closures.
5500 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5501
5502 workers()->run_task(&g1_par_task);
5503 end_par_time_sec = os::elapsedTime();
5504
5505 // Closing the inner scope will execute the destructor
5506 // for the G1RootProcessor object. We record the current
5507 // elapsed time before closing the scope so that time
5508 // taken for the destructor is NOT included in the
5509 // reported parallel time.
5510 }
5511
5512 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5513
5514 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5515 phase_times->record_par_time(par_time_ms);
5516
5517 double code_root_fixup_time_ms =
5518 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5519 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5520
5521 // Process any discovered reference objects - we have
5522 // to do this _before_ we retire the GC alloc regions
5523 // as we may have to copy some 'reachable' referent
5524 // objects (and their reachable sub-graphs) that were
5525 // not copied during the pause.
5526 process_discovered_references();
5527
5528 if (G1StringDedup::is_enabled()) {
5529 double fixup_start = os::elapsedTime();
5530
5531 G1STWIsAliveClosure is_alive(this);
5532 G1KeepAliveClosure keep_alive(this);
5533 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5534
5535 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5536 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5537 }
5538
5539 _allocator->release_gc_alloc_regions(evacuation_info);
5540 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5541
5542 // Reset and re-enable the hot card cache.
5543 // Note the counts for the cards in the regions in the
5544 // collection set are reset when the collection set is freed.
5545 hot_card_cache->reset_hot_cache();
5546 hot_card_cache->set_use_cache(true);
5547
5548 purge_code_root_memory();
5549
5550 if (evacuation_failed()) {
5551 remove_self_forwarding_pointers();
5552
5553 // Reset the G1EvacuationFailureALot counters and flags
5554 // Note: the values are reset only when an actual
5555 // evacuation failure occurs.
5556 NOT_PRODUCT(reset_evacuation_should_fail();)
5557 }
5558
5559 // Enqueue any remaining references remaining on the STW
5560 // reference processor's discovered lists. We need to do
5561 // this after the card table is cleaned (and verified) as
5562 // the act of enqueueing entries on to the pending list
5563 // will log these updates (and dirty their associated
5564 // cards). We need these updates logged to update any
5565 // RSets.
5566 enqueue_discovered_references();
5567
5568 redirty_logged_cards();
5569 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5570 }
5571
5572 void G1CollectedHeap::free_region(HeapRegion* hr,
5573 FreeRegionList* free_list,
5574 bool par,
5575 bool locked) {
5576 assert(!hr->is_free(), "the region should not be free");
5577 assert(!hr->is_empty(), "the region should not be empty");
5578 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5579 assert(free_list != NULL, "pre-condition");
5580
5581 if (G1VerifyBitmaps) {
5582 MemRegion mr(hr->bottom(), hr->end());
5583 concurrent_mark()->clearRangePrevBitmap(mr);
5584 }
5585
5586 // Clear the card counts for this region.
5587 // Note: we only need to do this if the region is not young
5588 // (since we don't refine cards in young regions).
5589 if (!hr->is_young()) {
5590 _cg1r->hot_card_cache()->reset_card_counts(hr);
5591 }
5592 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5593 free_list->add_ordered(hr);
5594 }
5595
5596 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5597 FreeRegionList* free_list,
5598 bool par) {
5599 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5600 assert(free_list != NULL, "pre-condition");
5601
5602 size_t hr_capacity = hr->capacity();
5603 // We need to read this before we make the region non-humongous,
5604 // otherwise the information will be gone.
5605 uint last_index = hr->last_hc_index();
5606 hr->clear_humongous();
5607 free_region(hr, free_list, par);
5608
5609 uint i = hr->hrm_index() + 1;
5610 while (i < last_index) {
5611 HeapRegion* curr_hr = region_at(i);
5612 assert(curr_hr->is_continues_humongous(), "invariant");
5613 curr_hr->clear_humongous();
5614 free_region(curr_hr, free_list, par);
5615 i += 1;
5616 }
5617 }
5618
5619 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5620 const HeapRegionSetCount& humongous_regions_removed) {
5621 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5622 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5623 _old_set.bulk_remove(old_regions_removed);
5624 _humongous_set.bulk_remove(humongous_regions_removed);
5625 }
5626
5627 }
5628
5629 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5630 assert(list != NULL, "list can't be null");
5631 if (!list->is_empty()) {
5632 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5633 _hrm.insert_list_into_free_list(list);
5634 }
5635 }
5636
5637 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5638 _allocator->decrease_used(bytes);
5639 }
5640
5641 class G1ParCleanupCTTask : public AbstractGangTask {
5642 G1SATBCardTableModRefBS* _ct_bs;
5643 G1CollectedHeap* _g1h;
5644 HeapRegion* volatile _su_head;
5645 public:
5646 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5647 G1CollectedHeap* g1h) :
5648 AbstractGangTask("G1 Par Cleanup CT Task"),
5649 _ct_bs(ct_bs), _g1h(g1h) { }
5650
5651 void work(uint worker_id) {
5652 HeapRegion* r;
5653 while (r = _g1h->pop_dirty_cards_region()) {
5654 clear_cards(r);
5655 }
5656 }
5657
5658 void clear_cards(HeapRegion* r) {
5659 // Cards of the survivors should have already been dirtied.
5660 if (!r->is_survivor()) {
5661 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5662 }
5663 }
5664 };
5665
5666 #ifndef PRODUCT
5667 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5668 G1CollectedHeap* _g1h;
5669 G1SATBCardTableModRefBS* _ct_bs;
5670 public:
5671 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5672 : _g1h(g1h), _ct_bs(ct_bs) { }
5673 virtual bool doHeapRegion(HeapRegion* r) {
5674 if (r->is_survivor()) {
5675 _g1h->verify_dirty_region(r);
5676 } else {
5677 _g1h->verify_not_dirty_region(r);
5678 }
5679 return false;
5680 }
5681 };
5682
5683 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5684 // All of the region should be clean.
5685 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5686 MemRegion mr(hr->bottom(), hr->end());
5687 ct_bs->verify_not_dirty_region(mr);
5688 }
5689
5690 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5691 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5692 // dirty allocated blocks as they allocate them. The thread that
5693 // retires each region and replaces it with a new one will do a
5694 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5695 // not dirty that area (one less thing to have to do while holding
5696 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5697 // is dirty.
5698 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5699 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5700 if (hr->is_young()) {
5701 ct_bs->verify_g1_young_region(mr);
5702 } else {
5703 ct_bs->verify_dirty_region(mr);
5704 }
5705 }
5706
5707 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5708 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5709 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5710 verify_dirty_region(hr);
5711 }
5712 }
5713
5714 void G1CollectedHeap::verify_dirty_young_regions() {
5715 verify_dirty_young_list(_young_list->first_region());
5716 }
5717
5718 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5719 HeapWord* tams, HeapWord* end) {
5720 guarantee(tams <= end,
5721 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5722 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5723 if (result < end) {
5724 gclog_or_tty->cr();
5725 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5726 bitmap_name, p2i(result));
5727 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5728 bitmap_name, p2i(tams), p2i(end));
5729 return false;
5730 }
5731 return true;
5732 }
5733
5734 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5735 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5736 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5737
5738 HeapWord* bottom = hr->bottom();
5739 HeapWord* ptams = hr->prev_top_at_mark_start();
5740 HeapWord* ntams = hr->next_top_at_mark_start();
5741 HeapWord* end = hr->end();
5742
5743 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5744
5745 bool res_n = true;
5746 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5747 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5748 // if we happen to be in that state.
5749 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5750 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5751 }
5752 if (!res_p || !res_n) {
5753 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5754 HR_FORMAT_PARAMS(hr));
5755 gclog_or_tty->print_cr("#### Caller: %s", caller);
5756 return false;
5757 }
5758 return true;
5759 }
5760
5761 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5762 if (!G1VerifyBitmaps) return;
5763
5764 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5765 }
5766
5767 class G1VerifyBitmapClosure : public HeapRegionClosure {
5768 private:
5769 const char* _caller;
5770 G1CollectedHeap* _g1h;
5771 bool _failures;
5772
5773 public:
5774 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5775 _caller(caller), _g1h(g1h), _failures(false) { }
5776
5777 bool failures() { return _failures; }
5778
5779 virtual bool doHeapRegion(HeapRegion* hr) {
5780 if (hr->is_continues_humongous()) return false;
5781
5782 bool result = _g1h->verify_bitmaps(_caller, hr);
5783 if (!result) {
5784 _failures = true;
5785 }
5786 return false;
5787 }
5788 };
5789
5790 void G1CollectedHeap::check_bitmaps(const char* caller) {
5791 if (!G1VerifyBitmaps) return;
5792
5793 G1VerifyBitmapClosure cl(caller, this);
5794 heap_region_iterate(&cl);
5795 guarantee(!cl.failures(), "bitmap verification");
5796 }
5797
5798 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5799 private:
5800 bool _failures;
5801 public:
5802 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5803
5804 virtual bool doHeapRegion(HeapRegion* hr) {
5805 uint i = hr->hrm_index();
5806 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5807 if (hr->is_humongous()) {
5808 if (hr->in_collection_set()) {
5809 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5810 _failures = true;
5811 return true;
5812 }
5813 if (cset_state.is_in_cset()) {
5814 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5815 _failures = true;
5816 return true;
5817 }
5818 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5819 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5820 _failures = true;
5821 return true;
5822 }
5823 } else {
5824 if (cset_state.is_humongous()) {
5825 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5826 _failures = true;
5827 return true;
5828 }
5829 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5830 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5831 hr->in_collection_set(), cset_state.value(), i);
5832 _failures = true;
5833 return true;
5834 }
5835 if (cset_state.is_in_cset()) {
5836 if (hr->is_young() != (cset_state.is_young())) {
5837 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5838 hr->is_young(), cset_state.value(), i);
5839 _failures = true;
5840 return true;
5841 }
5842 if (hr->is_old() != (cset_state.is_old())) {
5843 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5844 hr->is_old(), cset_state.value(), i);
5845 _failures = true;
5846 return true;
5847 }
5848 }
5849 }
5850 return false;
5851 }
5852
5853 bool failures() const { return _failures; }
5854 };
5855
5856 bool G1CollectedHeap::check_cset_fast_test() {
5857 G1CheckCSetFastTableClosure cl;
5858 _hrm.iterate(&cl);
5859 return !cl.failures();
5860 }
5861 #endif // PRODUCT
5862
5863 void G1CollectedHeap::cleanUpCardTable() {
5864 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5865 double start = os::elapsedTime();
5866
5867 {
5868 // Iterate over the dirty cards region list.
5869 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5870
5871 workers()->run_task(&cleanup_task);
5872 #ifndef PRODUCT
5873 if (G1VerifyCTCleanup || VerifyAfterGC) {
5874 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5875 heap_region_iterate(&cleanup_verifier);
5876 }
5877 #endif
5878 }
5879
5880 double elapsed = os::elapsedTime() - start;
5881 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5882 }
5883
5884 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5885 size_t pre_used = 0;
5886 FreeRegionList local_free_list("Local List for CSet Freeing");
5887
5888 double young_time_ms = 0.0;
5889 double non_young_time_ms = 0.0;
5890
5891 // Since the collection set is a superset of the the young list,
5892 // all we need to do to clear the young list is clear its
5893 // head and length, and unlink any young regions in the code below
5894 _young_list->clear();
5895
5896 G1CollectorPolicy* policy = g1_policy();
5897
5898 double start_sec = os::elapsedTime();
5899 bool non_young = true;
5900
5901 HeapRegion* cur = cs_head;
5902 int age_bound = -1;
5903 size_t rs_lengths = 0;
5904
5905 while (cur != NULL) {
5906 assert(!is_on_master_free_list(cur), "sanity");
5907 if (non_young) {
5908 if (cur->is_young()) {
5909 double end_sec = os::elapsedTime();
5910 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5911 non_young_time_ms += elapsed_ms;
5912
5913 start_sec = os::elapsedTime();
5914 non_young = false;
5915 }
5916 } else {
5917 if (!cur->is_young()) {
5918 double end_sec = os::elapsedTime();
5919 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5920 young_time_ms += elapsed_ms;
5921
5922 start_sec = os::elapsedTime();
5923 non_young = true;
5924 }
5925 }
5926
5927 rs_lengths += cur->rem_set()->occupied_locked();
5928
5929 HeapRegion* next = cur->next_in_collection_set();
5930 assert(cur->in_collection_set(), "bad CS");
5931 cur->set_next_in_collection_set(NULL);
5932 clear_in_cset(cur);
5933
5934 if (cur->is_young()) {
5935 int index = cur->young_index_in_cset();
5936 assert(index != -1, "invariant");
5937 assert((uint) index < policy->young_cset_region_length(), "invariant");
5938 size_t words_survived = _surviving_young_words[index];
5939 cur->record_surv_words_in_group(words_survived);
5940
5941 // At this point the we have 'popped' cur from the collection set
5942 // (linked via next_in_collection_set()) but it is still in the
5943 // young list (linked via next_young_region()). Clear the
5944 // _next_young_region field.
5945 cur->set_next_young_region(NULL);
5946 } else {
5947 int index = cur->young_index_in_cset();
5948 assert(index == -1, "invariant");
5949 }
5950
5951 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5952 (!cur->is_young() && cur->young_index_in_cset() == -1),
5953 "invariant" );
5954
5955 if (!cur->evacuation_failed()) {
5956 MemRegion used_mr = cur->used_region();
5957
5958 // And the region is empty.
5959 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5960 pre_used += cur->used();
5961 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5962 } else {
5963 cur->uninstall_surv_rate_group();
5964 if (cur->is_young()) {
5965 cur->set_young_index_in_cset(-1);
5966 }
5967 cur->set_evacuation_failed(false);
5968 // The region is now considered to be old.
5969 cur->set_old();
5970 _old_set.add(cur);
5971 evacuation_info.increment_collectionset_used_after(cur->used());
5972 }
5973 cur = next;
5974 }
5975
5976 evacuation_info.set_regions_freed(local_free_list.length());
5977 policy->record_max_rs_lengths(rs_lengths);
5978 policy->cset_regions_freed();
5979
5980 double end_sec = os::elapsedTime();
5981 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5982
5983 if (non_young) {
5984 non_young_time_ms += elapsed_ms;
5985 } else {
5986 young_time_ms += elapsed_ms;
5987 }
5988
5989 prepend_to_freelist(&local_free_list);
5990 decrement_summary_bytes(pre_used);
5991 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5992 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5993 }
5994
5995 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5996 private:
5997 FreeRegionList* _free_region_list;
5998 HeapRegionSet* _proxy_set;
5999 HeapRegionSetCount _humongous_regions_removed;
6000 size_t _freed_bytes;
6001 public:
6002
6003 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6004 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6005 }
6006
6007 virtual bool doHeapRegion(HeapRegion* r) {
6008 if (!r->is_starts_humongous()) {
6009 return false;
6010 }
6011
6012 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6013
6014 oop obj = (oop)r->bottom();
6015 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6016
6017 // The following checks whether the humongous object is live are sufficient.
6018 // The main additional check (in addition to having a reference from the roots
6019 // or the young gen) is whether the humongous object has a remembered set entry.
6020 //
6021 // A humongous object cannot be live if there is no remembered set for it
6022 // because:
6023 // - there can be no references from within humongous starts regions referencing
6024 // the object because we never allocate other objects into them.
6025 // (I.e. there are no intra-region references that may be missed by the
6026 // remembered set)
6027 // - as soon there is a remembered set entry to the humongous starts region
6028 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6029 // until the end of a concurrent mark.
6030 //
6031 // It is not required to check whether the object has been found dead by marking
6032 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6033 // all objects allocated during that time are considered live.
6034 // SATB marking is even more conservative than the remembered set.
6035 // So if at this point in the collection there is no remembered set entry,
6036 // nobody has a reference to it.
6037 // At the start of collection we flush all refinement logs, and remembered sets
6038 // are completely up-to-date wrt to references to the humongous object.
6039 //
6040 // Other implementation considerations:
6041 // - never consider object arrays at this time because they would pose
6042 // considerable effort for cleaning up the the remembered sets. This is
6043 // required because stale remembered sets might reference locations that
6044 // are currently allocated into.
6045 uint region_idx = r->hrm_index();
6046 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6047 !r->rem_set()->is_empty()) {
6048
6049 if (G1TraceEagerReclaimHumongousObjects) {
6050 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",
6051 region_idx,
6052 (size_t)obj->size() * HeapWordSize,
6053 p2i(r->bottom()),
6054 r->region_num(),
6055 r->rem_set()->occupied(),
6056 r->rem_set()->strong_code_roots_list_length(),
6057 next_bitmap->isMarked(r->bottom()),
6058 g1h->is_humongous_reclaim_candidate(region_idx),
6059 obj->is_typeArray()
6060 );
6061 }
6062
6063 return false;
6064 }
6065
6066 guarantee(obj->is_typeArray(),
6067 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6068 PTR_FORMAT " is not.",
6069 p2i(r->bottom())));
6070
6071 if (G1TraceEagerReclaimHumongousObjects) {
6072 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",
6073 region_idx,
6074 (size_t)obj->size() * HeapWordSize,
6075 p2i(r->bottom()),
6076 r->region_num(),
6077 r->rem_set()->occupied(),
6078 r->rem_set()->strong_code_roots_list_length(),
6079 next_bitmap->isMarked(r->bottom()),
6080 g1h->is_humongous_reclaim_candidate(region_idx),
6081 obj->is_typeArray()
6082 );
6083 }
6084 // Need to clear mark bit of the humongous object if already set.
6085 if (next_bitmap->isMarked(r->bottom())) {
6086 next_bitmap->clear(r->bottom());
6087 }
6088 _freed_bytes += r->used();
6089 r->set_containing_set(NULL);
6090 _humongous_regions_removed.increment(1u, r->capacity());
6091 g1h->free_humongous_region(r, _free_region_list, false);
6092
6093 return false;
6094 }
6095
6096 HeapRegionSetCount& humongous_free_count() {
6097 return _humongous_regions_removed;
6098 }
6099
6100 size_t bytes_freed() const {
6101 return _freed_bytes;
6102 }
6103
6104 size_t humongous_reclaimed() const {
6105 return _humongous_regions_removed.length();
6106 }
6107 };
6108
6109 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6110 assert_at_safepoint(true);
6111
6112 if (!G1EagerReclaimHumongousObjects ||
6113 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6114 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6115 return;
6116 }
6117
6118 double start_time = os::elapsedTime();
6119
6120 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6121
6122 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6123 heap_region_iterate(&cl);
6124
6125 HeapRegionSetCount empty_set;
6126 remove_from_old_sets(empty_set, cl.humongous_free_count());
6127
6128 G1HRPrinter* hrp = hr_printer();
6129 if (hrp->is_active()) {
6130 FreeRegionListIterator iter(&local_cleanup_list);
6131 while (iter.more_available()) {
6132 HeapRegion* hr = iter.get_next();
6133 hrp->cleanup(hr);
6134 }
6135 }
6136
6137 prepend_to_freelist(&local_cleanup_list);
6138 decrement_summary_bytes(cl.bytes_freed());
6139
6140 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6141 cl.humongous_reclaimed());
6142 }
6143
6144 // This routine is similar to the above but does not record
6145 // any policy statistics or update free lists; we are abandoning
6146 // the current incremental collection set in preparation of a
6147 // full collection. After the full GC we will start to build up
6148 // the incremental collection set again.
6149 // This is only called when we're doing a full collection
6150 // and is immediately followed by the tearing down of the young list.
6151
6152 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6153 HeapRegion* cur = cs_head;
6154
6155 while (cur != NULL) {
6156 HeapRegion* next = cur->next_in_collection_set();
6157 assert(cur->in_collection_set(), "bad CS");
6158 cur->set_next_in_collection_set(NULL);
6159 clear_in_cset(cur);
6160 cur->set_young_index_in_cset(-1);
6161 cur = next;
6162 }
6163 }
6164
6165 void G1CollectedHeap::set_free_regions_coming() {
6166 if (G1ConcRegionFreeingVerbose) {
6167 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6168 "setting free regions coming");
6169 }
6170
6171 assert(!free_regions_coming(), "pre-condition");
6172 _free_regions_coming = true;
6173 }
6174
6175 void G1CollectedHeap::reset_free_regions_coming() {
6176 assert(free_regions_coming(), "pre-condition");
6177
6178 {
6179 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6180 _free_regions_coming = false;
6181 SecondaryFreeList_lock->notify_all();
6182 }
6183
6184 if (G1ConcRegionFreeingVerbose) {
6185 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6186 "reset free regions coming");
6187 }
6188 }
6189
6190 void G1CollectedHeap::wait_while_free_regions_coming() {
6191 // Most of the time we won't have to wait, so let's do a quick test
6192 // first before we take the lock.
6193 if (!free_regions_coming()) {
6194 return;
6195 }
6196
6197 if (G1ConcRegionFreeingVerbose) {
6198 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6199 "waiting for free regions");
6200 }
6201
6202 {
6203 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6204 while (free_regions_coming()) {
6205 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6206 }
6207 }
6208
6209 if (G1ConcRegionFreeingVerbose) {
6210 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6211 "done waiting for free regions");
6212 }
6213 }
6214
6215 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6216 _young_list->push_region(hr);
6217 }
6218
6219 class NoYoungRegionsClosure: public HeapRegionClosure {
6220 private:
6221 bool _success;
6222 public:
6223 NoYoungRegionsClosure() : _success(true) { }
6224 bool doHeapRegion(HeapRegion* r) {
6225 if (r->is_young()) {
6226 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6227 p2i(r->bottom()), p2i(r->end()));
6228 _success = false;
6229 }
6230 return false;
6231 }
6232 bool success() { return _success; }
6233 };
6234
6235 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6236 bool ret = _young_list->check_list_empty(check_sample);
6237
6238 if (check_heap) {
6239 NoYoungRegionsClosure closure;
6240 heap_region_iterate(&closure);
6241 ret = ret && closure.success();
6242 }
6243
6244 return ret;
6245 }
6246
6247 class TearDownRegionSetsClosure : public HeapRegionClosure {
6248 private:
6249 HeapRegionSet *_old_set;
6250
6251 public:
6252 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6253
6254 bool doHeapRegion(HeapRegion* r) {
6255 if (r->is_old()) {
6256 _old_set->remove(r);
6257 } else {
6258 // We ignore free regions, we'll empty the free list afterwards.
6259 // We ignore young regions, we'll empty the young list afterwards.
6260 // We ignore humongous regions, we're not tearing down the
6261 // humongous regions set.
6262 assert(r->is_free() || r->is_young() || r->is_humongous(),
6263 "it cannot be another type");
6264 }
6265 return false;
6266 }
6267
6268 ~TearDownRegionSetsClosure() {
6269 assert(_old_set->is_empty(), "post-condition");
6270 }
6271 };
6272
6273 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6274 assert_at_safepoint(true /* should_be_vm_thread */);
6275
6276 if (!free_list_only) {
6277 TearDownRegionSetsClosure cl(&_old_set);
6278 heap_region_iterate(&cl);
6279
6280 // Note that emptying the _young_list is postponed and instead done as
6281 // the first step when rebuilding the regions sets again. The reason for
6282 // this is that during a full GC string deduplication needs to know if
6283 // a collected region was young or old when the full GC was initiated.
6284 }
6285 _hrm.remove_all_free_regions();
6286 }
6287
6288 class RebuildRegionSetsClosure : public HeapRegionClosure {
6289 private:
6290 bool _free_list_only;
6291 HeapRegionSet* _old_set;
6292 HeapRegionManager* _hrm;
6293 size_t _total_used;
6294
6295 public:
6296 RebuildRegionSetsClosure(bool free_list_only,
6297 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6298 _free_list_only(free_list_only),
6299 _old_set(old_set), _hrm(hrm), _total_used(0) {
6300 assert(_hrm->num_free_regions() == 0, "pre-condition");
6301 if (!free_list_only) {
6302 assert(_old_set->is_empty(), "pre-condition");
6303 }
6304 }
6305
6306 bool doHeapRegion(HeapRegion* r) {
6307 if (r->is_continues_humongous()) {
6308 return false;
6309 }
6310
6311 if (r->is_empty()) {
6312 // Add free regions to the free list
6313 r->set_free();
6314 r->set_allocation_context(AllocationContext::system());
6315 _hrm->insert_into_free_list(r);
6316 } else if (!_free_list_only) {
6317 assert(!r->is_young(), "we should not come across young regions");
6318
6319 if (r->is_humongous()) {
6320 // We ignore humongous regions. We left the humongous set unchanged.
6321 } else {
6322 // Objects that were compacted would have ended up on regions
6323 // that were previously old or free. Archive regions (which are
6324 // old) will not have been touched.
6325 assert(r->is_free() || r->is_old(), "invariant");
6326 // We now consider them old, so register as such. Leave
6327 // archive regions set that way, however, while still adding
6328 // them to the old set.
6329 if (!r->is_archive()) {
6330 r->set_old();
6331 }
6332 _old_set->add(r);
6333 }
6334 _total_used += r->used();
6335 }
6336
6337 return false;
6338 }
6339
6340 size_t total_used() {
6341 return _total_used;
6342 }
6343 };
6344
6345 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6346 assert_at_safepoint(true /* should_be_vm_thread */);
6347
6348 if (!free_list_only) {
6349 _young_list->empty_list();
6350 }
6351
6352 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6353 heap_region_iterate(&cl);
6354
6355 if (!free_list_only) {
6356 _allocator->set_used(cl.total_used());
6357 if (_archive_allocator != NULL) {
6358 _archive_allocator->clear_used();
6359 }
6360 }
6361 assert(_allocator->used_unlocked() == recalculate_used(),
6362 err_msg("inconsistent _allocator->used_unlocked(), "
6363 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6364 _allocator->used_unlocked(), recalculate_used()));
6365 }
6366
6367 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6368 _refine_cte_cl->set_concurrent(concurrent);
6369 }
6370
6371 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6372 HeapRegion* hr = heap_region_containing(p);
6373 return hr->is_in(p);
6374 }
6375
6376 // Methods for the mutator alloc region
6377
6378 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6379 bool force) {
6380 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6381 assert(!force || g1_policy()->can_expand_young_list(),
6382 "if force is true we should be able to expand the young list");
6383 bool young_list_full = g1_policy()->is_young_list_full();
6384 if (force || !young_list_full) {
6385 HeapRegion* new_alloc_region = new_region(word_size,
6386 false /* is_old */,
6387 false /* do_expand */);
6388 if (new_alloc_region != NULL) {
6389 set_region_short_lived_locked(new_alloc_region);
6390 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6391 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6392 return new_alloc_region;
6393 }
6394 }
6395 return NULL;
6396 }
6397
6398 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6399 size_t allocated_bytes) {
6400 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6401 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6402
6403 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6404 _allocator->increase_used(allocated_bytes);
6405 _hr_printer.retire(alloc_region);
6406 // We update the eden sizes here, when the region is retired,
6407 // instead of when it's allocated, since this is the point that its
6408 // used space has been recored in _summary_bytes_used.
6409 g1mm()->update_eden_size();
6410 }
6411
6412 // Methods for the GC alloc regions
6413
6414 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6415 uint count,
6416 InCSetState dest) {
6417 assert(FreeList_lock->owned_by_self(), "pre-condition");
6418
6419 if (count < g1_policy()->max_regions(dest)) {
6420 const bool is_survivor = (dest.is_young());
6421 HeapRegion* new_alloc_region = new_region(word_size,
6422 !is_survivor,
6423 true /* do_expand */);
6424 if (new_alloc_region != NULL) {
6425 // We really only need to do this for old regions given that we
6426 // should never scan survivors. But it doesn't hurt to do it
6427 // for survivors too.
6428 new_alloc_region->record_timestamp();
6429 if (is_survivor) {
6430 new_alloc_region->set_survivor();
6431 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6432 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6433 } else {
6434 new_alloc_region->set_old();
6435 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6436 check_bitmaps("Old Region Allocation", new_alloc_region);
6437 }
6438 bool during_im = collector_state()->during_initial_mark_pause();
6439 new_alloc_region->note_start_of_copying(during_im);
6440 return new_alloc_region;
6441 }
6442 }
6443 return NULL;
6444 }
6445
6446 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6447 size_t allocated_bytes,
6448 InCSetState dest) {
6449 bool during_im = collector_state()->during_initial_mark_pause();
6450 alloc_region->note_end_of_copying(during_im);
6451 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6452 if (dest.is_young()) {
6453 young_list()->add_survivor_region(alloc_region);
6454 } else {
6455 _old_set.add(alloc_region);
6456 }
6457 _hr_printer.retire(alloc_region);
6458 }
6459
6460 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6461 bool expanded = false;
6462 uint index = _hrm.find_highest_free(&expanded);
6463
6464 if (index != G1_NO_HRM_INDEX) {
6465 if (expanded) {
6466 ergo_verbose1(ErgoHeapSizing,
6467 "attempt heap expansion",
6468 ergo_format_reason("requested address range outside heap bounds")
6469 ergo_format_byte("region size"),
6470 HeapRegion::GrainWords * HeapWordSize);
6471 }
6472 _hrm.allocate_free_regions_starting_at(index, 1);
6473 return region_at(index);
6474 }
6475 return NULL;
6476 }
6477
6478
6479 // Heap region set verification
6480
6481 class VerifyRegionListsClosure : public HeapRegionClosure {
6482 private:
6483 HeapRegionSet* _old_set;
6484 HeapRegionSet* _humongous_set;
6485 HeapRegionManager* _hrm;
6486
6487 public:
6488 HeapRegionSetCount _old_count;
6489 HeapRegionSetCount _humongous_count;
6490 HeapRegionSetCount _free_count;
6491
6492 VerifyRegionListsClosure(HeapRegionSet* old_set,
6493 HeapRegionSet* humongous_set,
6494 HeapRegionManager* hrm) :
6495 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6496 _old_count(), _humongous_count(), _free_count(){ }
6497
6498 bool doHeapRegion(HeapRegion* hr) {
6499 if (hr->is_continues_humongous()) {
6500 return false;
6501 }
6502
6503 if (hr->is_young()) {
6504 // TODO
6505 } else if (hr->is_starts_humongous()) {
6506 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6507 _humongous_count.increment(1u, hr->capacity());
6508 } else if (hr->is_empty()) {
6509 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6510 _free_count.increment(1u, hr->capacity());
6511 } else if (hr->is_old()) {
6512 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6513 _old_count.increment(1u, hr->capacity());
6514 } else {
6515 // There are no other valid region types. Check for one invalid
6516 // one we can identify: pinned without old or humongous set.
6517 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6518 ShouldNotReachHere();
6519 }
6520 return false;
6521 }
6522
6523 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6524 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6525 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6526 old_set->total_capacity_bytes(), _old_count.capacity()));
6527
6528 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6529 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6530 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6531
6532 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()));
6533 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6534 free_list->total_capacity_bytes(), _free_count.capacity()));
6535 }
6536 };
6537
6538 void G1CollectedHeap::verify_region_sets() {
6539 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6540
6541 // First, check the explicit lists.
6542 _hrm.verify();
6543 {
6544 // Given that a concurrent operation might be adding regions to
6545 // the secondary free list we have to take the lock before
6546 // verifying it.
6547 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6548 _secondary_free_list.verify_list();
6549 }
6550
6551 // If a concurrent region freeing operation is in progress it will
6552 // be difficult to correctly attributed any free regions we come
6553 // across to the correct free list given that they might belong to
6554 // one of several (free_list, secondary_free_list, any local lists,
6555 // etc.). So, if that's the case we will skip the rest of the
6556 // verification operation. Alternatively, waiting for the concurrent
6557 // operation to complete will have a non-trivial effect on the GC's
6558 // operation (no concurrent operation will last longer than the
6559 // interval between two calls to verification) and it might hide
6560 // any issues that we would like to catch during testing.
6561 if (free_regions_coming()) {
6562 return;
6563 }
6564
6565 // Make sure we append the secondary_free_list on the free_list so
6566 // that all free regions we will come across can be safely
6567 // attributed to the free_list.
6568 append_secondary_free_list_if_not_empty_with_lock();
6569
6570 // Finally, make sure that the region accounting in the lists is
6571 // consistent with what we see in the heap.
6572
6573 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6574 heap_region_iterate(&cl);
6575 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6576 }
6577
6578 // Optimized nmethod scanning
6579
6580 class RegisterNMethodOopClosure: public OopClosure {
6581 G1CollectedHeap* _g1h;
6582 nmethod* _nm;
6583
6584 template <class T> void do_oop_work(T* p) {
6585 T heap_oop = oopDesc::load_heap_oop(p);
6586 if (!oopDesc::is_null(heap_oop)) {
6587 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6588 HeapRegion* hr = _g1h->heap_region_containing(obj);
6589 assert(!hr->is_continues_humongous(),
6590 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6591 " starting at " HR_FORMAT,
6592 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6593
6594 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6595 hr->add_strong_code_root_locked(_nm);
6596 }
6597 }
6598
6599 public:
6600 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6601 _g1h(g1h), _nm(nm) {}
6602
6603 void do_oop(oop* p) { do_oop_work(p); }
6604 void do_oop(narrowOop* p) { do_oop_work(p); }
6605 };
6606
6607 class UnregisterNMethodOopClosure: public OopClosure {
6608 G1CollectedHeap* _g1h;
6609 nmethod* _nm;
6610
6611 template <class T> void do_oop_work(T* p) {
6612 T heap_oop = oopDesc::load_heap_oop(p);
6613 if (!oopDesc::is_null(heap_oop)) {
6614 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6615 HeapRegion* hr = _g1h->heap_region_containing(obj);
6616 assert(!hr->is_continues_humongous(),
6617 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6618 " starting at " HR_FORMAT,
6619 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6620
6621 hr->remove_strong_code_root(_nm);
6622 }
6623 }
6624
6625 public:
6626 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6627 _g1h(g1h), _nm(nm) {}
6628
6629 void do_oop(oop* p) { do_oop_work(p); }
6630 void do_oop(narrowOop* p) { do_oop_work(p); }
6631 };
6632
6633 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6634 CollectedHeap::register_nmethod(nm);
6635
6636 guarantee(nm != NULL, "sanity");
6637 RegisterNMethodOopClosure reg_cl(this, nm);
6638 nm->oops_do(®_cl);
6639 }
6640
6641 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6642 CollectedHeap::unregister_nmethod(nm);
6643
6644 guarantee(nm != NULL, "sanity");
6645 UnregisterNMethodOopClosure reg_cl(this, nm);
6646 nm->oops_do(®_cl, true);
6647 }
6648
6649 void G1CollectedHeap::purge_code_root_memory() {
6650 double purge_start = os::elapsedTime();
6651 G1CodeRootSet::purge();
6652 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6653 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6654 }
6655
6656 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6657 G1CollectedHeap* _g1h;
6658
6659 public:
6660 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6661 _g1h(g1h) {}
6662
6663 void do_code_blob(CodeBlob* cb) {
6664 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6665 if (nm == NULL) {
6666 return;
6667 }
6668
6669 if (ScavengeRootsInCode) {
6670 _g1h->register_nmethod(nm);
6671 }
6672 }
6673 };
6674
6675 void G1CollectedHeap::rebuild_strong_code_roots() {
6676 RebuildStrongCodeRootClosure blob_cl(this);
6677 CodeCache::blobs_do(&blob_cl);
6678 }