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 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 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 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 increase_used(fill_size * HeapWordSize);
1108 }
1109 }
1110 }
1111
1112 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1113 uint* gc_count_before_ret,
1114 uint* gclocker_retry_count_ret) {
1115 // The structure of this method has a lot of similarities to
1116 // attempt_allocation_slow(). The reason these two were not merged
1117 // into a single one is that such a method would require several "if
1118 // allocation is not humongous do this, otherwise do that"
1119 // conditional paths which would obscure its flow. In fact, an early
1120 // version of this code did use a unified method which was harder to
1121 // follow and, as a result, it had subtle bugs that were hard to
1122 // track down. So keeping these two methods separate allows each to
1123 // be more readable. It will be good to keep these two in sync as
1124 // much as possible.
1125
1126 assert_heap_not_locked_and_not_at_safepoint();
1127 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1128 "should only be called for humongous allocations");
1129
1130 // Humongous objects can exhaust the heap quickly, so we should check if we
1131 // need to start a marking cycle at each humongous object allocation. We do
1132 // the check before we do the actual allocation. The reason for doing it
1133 // before the allocation is that we avoid having to keep track of the newly
1134 // allocated memory while we do a GC.
1135 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1136 word_size)) {
1137 collect(GCCause::_g1_humongous_allocation);
1138 }
1139
1140 // We will loop until a) we manage to successfully perform the
1141 // allocation or b) we successfully schedule a collection which
1142 // fails to perform the allocation. b) is the only case when we'll
1143 // return NULL.
1144 HeapWord* result = NULL;
1145 for (int try_count = 1; /* we'll return */; try_count += 1) {
1146 bool should_try_gc;
1147 uint gc_count_before;
1148
1149 {
1150 MutexLockerEx x(Heap_lock);
1151
1152 // Given that humongous objects are not allocated in young
1153 // regions, we'll first try to do the allocation without doing a
1154 // collection hoping that there's enough space in the heap.
1155 result = humongous_obj_allocate(word_size, AllocationContext::current());
1156 if (result != NULL) {
1157 return result;
1158 }
1159
1160 if (GC_locker::is_active_and_needs_gc()) {
1161 should_try_gc = false;
1162 } else {
1163 // The GCLocker may not be active but the GCLocker initiated
1164 // GC may not yet have been performed (GCLocker::needs_gc()
1165 // returns true). In this case we do not try this GC and
1166 // wait until the GCLocker initiated GC is performed, and
1167 // then retry the allocation.
1168 if (GC_locker::needs_gc()) {
1169 should_try_gc = false;
1170 } else {
1171 // Read the GC count while still holding the Heap_lock.
1172 gc_count_before = total_collections();
1173 should_try_gc = true;
1174 }
1175 }
1176 }
1177
1178 if (should_try_gc) {
1179 // If we failed to allocate the humongous object, we should try to
1180 // do a collection pause (if we're allowed) in case it reclaims
1181 // enough space for the allocation to succeed after the pause.
1182
1183 bool succeeded;
1184 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1185 GCCause::_g1_humongous_allocation);
1186 if (result != NULL) {
1187 assert(succeeded, "only way to get back a non-NULL result");
1188 return result;
1189 }
1190
1191 if (succeeded) {
1192 // If we get here we successfully scheduled a collection which
1193 // failed to allocate. No point in trying to allocate
1194 // further. We'll just return NULL.
1195 MutexLockerEx x(Heap_lock);
1196 *gc_count_before_ret = total_collections();
1197 return NULL;
1198 }
1199 } else {
1200 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1201 MutexLockerEx x(Heap_lock);
1202 *gc_count_before_ret = total_collections();
1203 return NULL;
1204 }
1205 // The GCLocker is either active or the GCLocker initiated
1206 // GC has not yet been performed. Stall until it is and
1207 // then retry the allocation.
1208 GC_locker::stall_until_clear();
1209 (*gclocker_retry_count_ret) += 1;
1210 }
1211
1212 // We can reach here if we were unsuccessful in scheduling a
1213 // collection (because another thread beat us to it) or if we were
1214 // stalled due to the GC locker. In either can we should retry the
1215 // allocation attempt in case another thread successfully
1216 // performed a collection and reclaimed enough space. Give a
1217 // warning if we seem to be looping forever.
1218
1219 if ((QueuedAllocationWarningCount > 0) &&
1220 (try_count % QueuedAllocationWarningCount == 0)) {
1221 warning("G1CollectedHeap::attempt_allocation_humongous() "
1222 "retries %d times", try_count);
1223 }
1224 }
1225
1226 ShouldNotReachHere();
1227 return NULL;
1228 }
1229
1230 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1231 AllocationContext_t context,
1232 bool expect_null_mutator_alloc_region) {
1233 assert_at_safepoint(true /* should_be_vm_thread */);
1234 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1235 !expect_null_mutator_alloc_region,
1236 "the current alloc region was unexpectedly found to be non-NULL");
1237
1238 if (!is_humongous(word_size)) {
1239 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1240 false /* bot_updates */);
1241 } else {
1242 HeapWord* result = humongous_obj_allocate(word_size, context);
1243 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1244 collector_state()->set_initiate_conc_mark_if_possible(true);
1245 }
1246 return result;
1247 }
1248
1249 ShouldNotReachHere();
1250 }
1251
1252 class PostMCRemSetClearClosure: public HeapRegionClosure {
1253 G1CollectedHeap* _g1h;
1254 ModRefBarrierSet* _mr_bs;
1255 public:
1256 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1257 _g1h(g1h), _mr_bs(mr_bs) {}
1258
1259 bool doHeapRegion(HeapRegion* r) {
1260 HeapRegionRemSet* hrrs = r->rem_set();
1261
1262 if (r->is_continues_humongous()) {
1263 // We'll assert that the strong code root list and RSet is empty
1264 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1265 assert(hrrs->occupied() == 0, "RSet should be empty");
1266 return false;
1267 }
1268
1269 _g1h->reset_gc_time_stamps(r);
1270 hrrs->clear();
1271 // You might think here that we could clear just the cards
1272 // corresponding to the used region. But no: if we leave a dirty card
1273 // in a region we might allocate into, then it would prevent that card
1274 // from being enqueued, and cause it to be missed.
1275 // Re: the performance cost: we shouldn't be doing full GC anyway!
1276 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1277
1278 return false;
1279 }
1280 };
1281
1282 void G1CollectedHeap::clear_rsets_post_compaction() {
1283 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1284 heap_region_iterate(&rs_clear);
1285 }
1286
1287 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1288 G1CollectedHeap* _g1h;
1289 UpdateRSOopClosure _cl;
1290 public:
1291 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1292 _cl(g1->g1_rem_set(), worker_i),
1293 _g1h(g1)
1294 { }
1295
1296 bool doHeapRegion(HeapRegion* r) {
1297 if (!r->is_continues_humongous()) {
1298 _cl.set_from(r);
1299 r->oop_iterate(&_cl);
1300 }
1301 return false;
1302 }
1303 };
1304
1305 class ParRebuildRSTask: public AbstractGangTask {
1306 G1CollectedHeap* _g1;
1307 HeapRegionClaimer _hrclaimer;
1308
1309 public:
1310 ParRebuildRSTask(G1CollectedHeap* g1) :
1311 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1312
1313 void work(uint worker_id) {
1314 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1315 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1316 }
1317 };
1318
1319 class PostCompactionPrinterClosure: public HeapRegionClosure {
1320 private:
1321 G1HRPrinter* _hr_printer;
1322 public:
1323 bool doHeapRegion(HeapRegion* hr) {
1324 assert(!hr->is_young(), "not expecting to find young regions");
1325 if (hr->is_free()) {
1326 // We only generate output for non-empty regions.
1327 } else if (hr->is_starts_humongous()) {
1328 if (hr->region_num() == 1) {
1329 // single humongous region
1330 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1331 } else {
1332 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1333 }
1334 } else if (hr->is_continues_humongous()) {
1335 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1336 } else if (hr->is_archive()) {
1337 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1338 } else if (hr->is_old()) {
1339 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1340 } else {
1341 ShouldNotReachHere();
1342 }
1343 return false;
1344 }
1345
1346 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1347 : _hr_printer(hr_printer) { }
1348 };
1349
1350 void G1CollectedHeap::print_hrm_post_compaction() {
1351 PostCompactionPrinterClosure cl(hr_printer());
1352 heap_region_iterate(&cl);
1353 }
1354
1355 bool G1CollectedHeap::do_collection(bool explicit_gc,
1356 bool clear_all_soft_refs,
1357 size_t word_size) {
1358 assert_at_safepoint(true /* should_be_vm_thread */);
1359
1360 if (GC_locker::check_active_before_gc()) {
1361 return false;
1362 }
1363
1364 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1365 gc_timer->register_gc_start();
1366
1367 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1368 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1369
1370 SvcGCMarker sgcm(SvcGCMarker::FULL);
1371 ResourceMark rm;
1372
1373 G1Log::update_level();
1374 print_heap_before_gc();
1375 trace_heap_before_gc(gc_tracer);
1376
1377 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1378
1379 verify_region_sets_optional();
1380
1381 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1382 collector_policy()->should_clear_all_soft_refs();
1383
1384 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1385
1386 {
1387 IsGCActiveMark x;
1388
1389 // Timing
1390 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1391 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1392
1393 {
1394 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1395 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1396 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1397
1398 g1_policy()->record_full_collection_start();
1399
1400 // Note: When we have a more flexible GC logging framework that
1401 // allows us to add optional attributes to a GC log record we
1402 // could consider timing and reporting how long we wait in the
1403 // following two methods.
1404 wait_while_free_regions_coming();
1405 // If we start the compaction before the CM threads finish
1406 // scanning the root regions we might trip them over as we'll
1407 // be moving objects / updating references. So let's wait until
1408 // they are done. By telling them to abort, they should complete
1409 // early.
1410 _cm->root_regions()->abort();
1411 _cm->root_regions()->wait_until_scan_finished();
1412 append_secondary_free_list_if_not_empty_with_lock();
1413
1414 gc_prologue(true);
1415 increment_total_collections(true /* full gc */);
1416 increment_old_marking_cycles_started();
1417
1418 assert(used() == recalculate_used(), "Should be equal");
1419
1420 verify_before_gc();
1421
1422 check_bitmaps("Full GC Start");
1423 pre_full_gc_dump(gc_timer);
1424
1425 COMPILER2_PRESENT(DerivedPointerTable::clear());
1426
1427 // Disable discovery and empty the discovered lists
1428 // for the CM ref processor.
1429 ref_processor_cm()->disable_discovery();
1430 ref_processor_cm()->abandon_partial_discovery();
1431 ref_processor_cm()->verify_no_references_recorded();
1432
1433 // Abandon current iterations of concurrent marking and concurrent
1434 // refinement, if any are in progress. We have to do this before
1435 // wait_until_scan_finished() below.
1436 concurrent_mark()->abort();
1437
1438 // Make sure we'll choose a new allocation region afterwards.
1439 _allocator->release_mutator_alloc_region();
1440 _allocator->abandon_gc_alloc_regions();
1441 g1_rem_set()->cleanupHRRS();
1442
1443 // We should call this after we retire any currently active alloc
1444 // regions so that all the ALLOC / RETIRE events are generated
1445 // before the start GC event.
1446 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1447
1448 // We may have added regions to the current incremental collection
1449 // set between the last GC or pause and now. We need to clear the
1450 // incremental collection set and then start rebuilding it afresh
1451 // after this full GC.
1452 abandon_collection_set(g1_policy()->inc_cset_head());
1453 g1_policy()->clear_incremental_cset();
1454 g1_policy()->stop_incremental_cset_building();
1455
1456 tear_down_region_sets(false /* free_list_only */);
1457 collector_state()->set_gcs_are_young(true);
1458
1459 // See the comments in g1CollectedHeap.hpp and
1460 // G1CollectedHeap::ref_processing_init() about
1461 // how reference processing currently works in G1.
1462
1463 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1464 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1465
1466 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1467 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1468
1469 ref_processor_stw()->enable_discovery();
1470 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1471
1472 // Do collection work
1473 {
1474 HandleMark hm; // Discard invalid handles created during gc
1475 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1476 }
1477
1478 assert(num_free_regions() == 0, "we should not have added any free regions");
1479 rebuild_region_sets(false /* free_list_only */);
1480
1481 // Enqueue any discovered reference objects that have
1482 // not been removed from the discovered lists.
1483 ref_processor_stw()->enqueue_discovered_references();
1484
1485 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1486
1487 MemoryService::track_memory_usage();
1488
1489 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1490 ref_processor_stw()->verify_no_references_recorded();
1491
1492 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1493 ClassLoaderDataGraph::purge();
1494 MetaspaceAux::verify_metrics();
1495
1496 // Note: since we've just done a full GC, concurrent
1497 // marking is no longer active. Therefore we need not
1498 // re-enable reference discovery for the CM ref processor.
1499 // That will be done at the start of the next marking cycle.
1500 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1501 ref_processor_cm()->verify_no_references_recorded();
1502
1503 reset_gc_time_stamp();
1504 // Since everything potentially moved, we will clear all remembered
1505 // sets, and clear all cards. Later we will rebuild remembered
1506 // sets. We will also reset the GC time stamps of the regions.
1507 clear_rsets_post_compaction();
1508 check_gc_time_stamps();
1509
1510 // Resize the heap if necessary.
1511 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1512
1513 if (_hr_printer.is_active()) {
1514 // We should do this after we potentially resize the heap so
1515 // that all the COMMIT / UNCOMMIT events are generated before
1516 // the end GC event.
1517
1518 print_hrm_post_compaction();
1519 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1520 }
1521
1522 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1523 if (hot_card_cache->use_cache()) {
1524 hot_card_cache->reset_card_counts();
1525 hot_card_cache->reset_hot_cache();
1526 }
1527
1528 // Rebuild remembered sets of all regions.
1529 uint n_workers =
1530 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1531 workers()->active_workers(),
1532 Threads::number_of_non_daemon_threads());
1533 workers()->set_active_workers(n_workers);
1534
1535 ParRebuildRSTask rebuild_rs_task(this);
1536 workers()->run_task(&rebuild_rs_task);
1537
1538 // Rebuild the strong code root lists for each region
1539 rebuild_strong_code_roots();
1540
1541 if (true) { // FIXME
1542 MetaspaceGC::compute_new_size();
1543 }
1544
1545 #ifdef TRACESPINNING
1546 ParallelTaskTerminator::print_termination_counts();
1547 #endif
1548
1549 // Discard all rset updates
1550 JavaThread::dirty_card_queue_set().abandon_logs();
1551 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1552
1553 _young_list->reset_sampled_info();
1554 // At this point there should be no regions in the
1555 // entire heap tagged as young.
1556 assert(check_young_list_empty(true /* check_heap */),
1557 "young list should be empty at this point");
1558
1559 // Update the number of full collections that have been completed.
1560 increment_old_marking_cycles_completed(false /* concurrent */);
1561
1562 _hrm.verify_optional();
1563 verify_region_sets_optional();
1564
1565 verify_after_gc();
1566
1567 // Clear the previous marking bitmap, if needed for bitmap verification.
1568 // Note we cannot do this when we clear the next marking bitmap in
1569 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1570 // objects marked during a full GC against the previous bitmap.
1571 // But we need to clear it before calling check_bitmaps below since
1572 // the full GC has compacted objects and updated TAMS but not updated
1573 // the prev bitmap.
1574 if (G1VerifyBitmaps) {
1575 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1576 }
1577 check_bitmaps("Full GC End");
1578
1579 // Start a new incremental collection set for the next pause
1580 assert(g1_policy()->collection_set() == NULL, "must be");
1581 g1_policy()->start_incremental_cset_building();
1582
1583 clear_cset_fast_test();
1584
1585 _allocator->init_mutator_alloc_region();
1586
1587 g1_policy()->record_full_collection_end();
1588
1589 if (G1Log::fine()) {
1590 g1_policy()->print_heap_transition();
1591 }
1592
1593 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1594 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1595 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1596 // before any GC notifications are raised.
1597 g1mm()->update_sizes();
1598
1599 gc_epilogue(true);
1600 }
1601
1602 if (G1Log::finer()) {
1603 g1_policy()->print_detailed_heap_transition(true /* full */);
1604 }
1605
1606 print_heap_after_gc();
1607 trace_heap_after_gc(gc_tracer);
1608
1609 post_full_gc_dump(gc_timer);
1610
1611 gc_timer->register_gc_end();
1612 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1613 }
1614
1615 return true;
1616 }
1617
1618 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1619 // do_collection() will return whether it succeeded in performing
1620 // the GC. Currently, there is no facility on the
1621 // do_full_collection() API to notify the caller than the collection
1622 // did not succeed (e.g., because it was locked out by the GC
1623 // locker). So, right now, we'll ignore the return value.
1624 bool dummy = do_collection(true, /* explicit_gc */
1625 clear_all_soft_refs,
1626 0 /* word_size */);
1627 }
1628
1629 // This code is mostly copied from TenuredGeneration.
1630 void
1631 G1CollectedHeap::
1632 resize_if_necessary_after_full_collection(size_t word_size) {
1633 // Include the current allocation, if any, and bytes that will be
1634 // pre-allocated to support collections, as "used".
1635 const size_t used_after_gc = used();
1636 const size_t capacity_after_gc = capacity();
1637 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1638
1639 // This is enforced in arguments.cpp.
1640 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1641 "otherwise the code below doesn't make sense");
1642
1643 // We don't have floating point command-line arguments
1644 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1645 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1646 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1647 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1648
1649 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1650 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1651
1652 // We have to be careful here as these two calculations can overflow
1653 // 32-bit size_t's.
1654 double used_after_gc_d = (double) used_after_gc;
1655 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1656 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1657
1658 // Let's make sure that they are both under the max heap size, which
1659 // by default will make them fit into a size_t.
1660 double desired_capacity_upper_bound = (double) max_heap_size;
1661 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1662 desired_capacity_upper_bound);
1663 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1664 desired_capacity_upper_bound);
1665
1666 // We can now safely turn them into size_t's.
1667 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1668 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1669
1670 // This assert only makes sense here, before we adjust them
1671 // with respect to the min and max heap size.
1672 assert(minimum_desired_capacity <= maximum_desired_capacity,
1673 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1674 "maximum_desired_capacity = " SIZE_FORMAT,
1675 minimum_desired_capacity, maximum_desired_capacity));
1676
1677 // Should not be greater than the heap max size. No need to adjust
1678 // it with respect to the heap min size as it's a lower bound (i.e.,
1679 // we'll try to make the capacity larger than it, not smaller).
1680 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1681 // Should not be less than the heap min size. No need to adjust it
1682 // with respect to the heap max size as it's an upper bound (i.e.,
1683 // we'll try to make the capacity smaller than it, not greater).
1684 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1685
1686 if (capacity_after_gc < minimum_desired_capacity) {
1687 // Don't expand unless it's significant
1688 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1689 ergo_verbose4(ErgoHeapSizing,
1690 "attempt heap expansion",
1691 ergo_format_reason("capacity lower than "
1692 "min desired capacity after Full GC")
1693 ergo_format_byte("capacity")
1694 ergo_format_byte("occupancy")
1695 ergo_format_byte_perc("min desired capacity"),
1696 capacity_after_gc, used_after_gc,
1697 minimum_desired_capacity, (double) MinHeapFreeRatio);
1698 expand(expand_bytes);
1699
1700 // No expansion, now see if we want to shrink
1701 } else if (capacity_after_gc > maximum_desired_capacity) {
1702 // Capacity too large, compute shrinking size
1703 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1704 ergo_verbose4(ErgoHeapSizing,
1705 "attempt heap shrinking",
1706 ergo_format_reason("capacity higher than "
1707 "max desired capacity after Full GC")
1708 ergo_format_byte("capacity")
1709 ergo_format_byte("occupancy")
1710 ergo_format_byte_perc("max desired capacity"),
1711 capacity_after_gc, used_after_gc,
1712 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1713 shrink(shrink_bytes);
1714 }
1715 }
1716
1717
1718 HeapWord*
1719 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1720 AllocationContext_t context,
1721 bool* succeeded) {
1722 assert_at_safepoint(true /* should_be_vm_thread */);
1723
1724 *succeeded = true;
1725 // Let's attempt the allocation first.
1726 HeapWord* result =
1727 attempt_allocation_at_safepoint(word_size,
1728 context,
1729 false /* expect_null_mutator_alloc_region */);
1730 if (result != NULL) {
1731 assert(*succeeded, "sanity");
1732 return result;
1733 }
1734
1735 // In a G1 heap, we're supposed to keep allocation from failing by
1736 // incremental pauses. Therefore, at least for now, we'll favor
1737 // expansion over collection. (This might change in the future if we can
1738 // do something smarter than full collection to satisfy a failed alloc.)
1739 result = expand_and_allocate(word_size, context);
1740 if (result != NULL) {
1741 assert(*succeeded, "sanity");
1742 return result;
1743 }
1744
1745 // Expansion didn't work, we'll try to do a Full GC.
1746 bool gc_succeeded = do_collection(false, /* explicit_gc */
1747 false, /* clear_all_soft_refs */
1748 word_size);
1749 if (!gc_succeeded) {
1750 *succeeded = false;
1751 return NULL;
1752 }
1753
1754 // Retry the allocation
1755 result = attempt_allocation_at_safepoint(word_size,
1756 context,
1757 true /* expect_null_mutator_alloc_region */);
1758 if (result != NULL) {
1759 assert(*succeeded, "sanity");
1760 return result;
1761 }
1762
1763 // Then, try a Full GC that will collect all soft references.
1764 gc_succeeded = do_collection(false, /* explicit_gc */
1765 true, /* clear_all_soft_refs */
1766 word_size);
1767 if (!gc_succeeded) {
1768 *succeeded = false;
1769 return NULL;
1770 }
1771
1772 // Retry the allocation once more
1773 result = attempt_allocation_at_safepoint(word_size,
1774 context,
1775 true /* expect_null_mutator_alloc_region */);
1776 if (result != NULL) {
1777 assert(*succeeded, "sanity");
1778 return result;
1779 }
1780
1781 assert(!collector_policy()->should_clear_all_soft_refs(),
1782 "Flag should have been handled and cleared prior to this point");
1783
1784 // What else? We might try synchronous finalization later. If the total
1785 // space available is large enough for the allocation, then a more
1786 // complete compaction phase than we've tried so far might be
1787 // appropriate.
1788 assert(*succeeded, "sanity");
1789 return NULL;
1790 }
1791
1792 // Attempting to expand the heap sufficiently
1793 // to support an allocation of the given "word_size". If
1794 // successful, perform the allocation and return the address of the
1795 // allocated block, or else "NULL".
1796
1797 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1798 assert_at_safepoint(true /* should_be_vm_thread */);
1799
1800 verify_region_sets_optional();
1801
1802 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1803 ergo_verbose1(ErgoHeapSizing,
1804 "attempt heap expansion",
1805 ergo_format_reason("allocation request failed")
1806 ergo_format_byte("allocation request"),
1807 word_size * HeapWordSize);
1808 if (expand(expand_bytes)) {
1809 _hrm.verify_optional();
1810 verify_region_sets_optional();
1811 return attempt_allocation_at_safepoint(word_size,
1812 context,
1813 false /* expect_null_mutator_alloc_region */);
1814 }
1815 return NULL;
1816 }
1817
1818 bool G1CollectedHeap::expand(size_t expand_bytes) {
1819 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1820 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1821 HeapRegion::GrainBytes);
1822 ergo_verbose2(ErgoHeapSizing,
1823 "expand the heap",
1824 ergo_format_byte("requested expansion amount")
1825 ergo_format_byte("attempted expansion amount"),
1826 expand_bytes, aligned_expand_bytes);
1827
1828 if (is_maximal_no_gc()) {
1829 ergo_verbose0(ErgoHeapSizing,
1830 "did not expand the heap",
1831 ergo_format_reason("heap already fully expanded"));
1832 return false;
1833 }
1834
1835 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1836 assert(regions_to_expand > 0, "Must expand by at least one region");
1837
1838 uint expanded_by = _hrm.expand_by(regions_to_expand);
1839
1840 if (expanded_by > 0) {
1841 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1842 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1843 g1_policy()->record_new_heap_size(num_regions());
1844 } else {
1845 ergo_verbose0(ErgoHeapSizing,
1846 "did not expand the heap",
1847 ergo_format_reason("heap expansion operation failed"));
1848 // The expansion of the virtual storage space was unsuccessful.
1849 // Let's see if it was because we ran out of swap.
1850 if (G1ExitOnExpansionFailure &&
1851 _hrm.available() >= regions_to_expand) {
1852 // We had head room...
1853 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1854 }
1855 }
1856 return regions_to_expand > 0;
1857 }
1858
1859 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1860 size_t aligned_shrink_bytes =
1861 ReservedSpace::page_align_size_down(shrink_bytes);
1862 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863 HeapRegion::GrainBytes);
1864 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865
1866 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1867 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1868
1869 ergo_verbose3(ErgoHeapSizing,
1870 "shrink the heap",
1871 ergo_format_byte("requested shrinking amount")
1872 ergo_format_byte("aligned shrinking amount")
1873 ergo_format_byte("attempted shrinking amount"),
1874 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1875 if (num_regions_removed > 0) {
1876 g1_policy()->record_new_heap_size(num_regions());
1877 } else {
1878 ergo_verbose0(ErgoHeapSizing,
1879 "did not shrink the heap",
1880 ergo_format_reason("heap shrinking operation failed"));
1881 }
1882 }
1883
1884 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1885 verify_region_sets_optional();
1886
1887 // We should only reach here at the end of a Full GC which means we
1888 // should not not be holding to any GC alloc regions. The method
1889 // below will make sure of that and do any remaining clean up.
1890 _allocator->abandon_gc_alloc_regions();
1891
1892 // Instead of tearing down / rebuilding the free lists here, we
1893 // could instead use the remove_all_pending() method on free_list to
1894 // remove only the ones that we need to remove.
1895 tear_down_region_sets(true /* free_list_only */);
1896 shrink_helper(shrink_bytes);
1897 rebuild_region_sets(true /* free_list_only */);
1898
1899 _hrm.verify_optional();
1900 verify_region_sets_optional();
1901 }
1902
1903 // Public methods.
1904
1905 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1906 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1907 #endif // _MSC_VER
1908
1909
1910 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1911 CollectedHeap(),
1912 _g1_policy(policy_),
1913 _dirty_card_queue_set(false),
1914 _into_cset_dirty_card_queue_set(false),
1915 _is_alive_closure_cm(this),
1916 _is_alive_closure_stw(this),
1917 _ref_processor_cm(NULL),
1918 _ref_processor_stw(NULL),
1919 _bot_shared(NULL),
1920 _evac_failure_scan_stack(NULL),
1921 _cg1r(NULL),
1922 _g1mm(NULL),
1923 _refine_cte_cl(NULL),
1924 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1925 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1926 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1927 _humongous_reclaim_candidates(),
1928 _has_humongous_reclaim_candidates(false),
1929 _archive_allocator(NULL),
1930 _free_regions_coming(false),
1931 _young_list(new YoungList(this)),
1932 _gc_time_stamp(0),
1933 _summary_bytes_used(0),
1934 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1935 _old_plab_stats(OldPLABSize, PLABWeight),
1936 _expand_heap_after_alloc_failure(true),
1937 _surviving_young_words(NULL),
1938 _old_marking_cycles_started(0),
1939 _old_marking_cycles_completed(0),
1940 _heap_summary_sent(false),
1941 _in_cset_fast_test(),
1942 _dirty_cards_region_list(NULL),
1943 _worker_cset_start_region(NULL),
1944 _worker_cset_start_region_time_stamp(NULL),
1945 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1946 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1947 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1948 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1949
1950 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1951 /* are_GC_task_threads */true,
1952 /* are_ConcurrentGC_threads */false);
1953 _workers->initialize_workers();
1954
1955 _allocator = G1Allocator::create_allocator(this);
1956 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1957
1958 // Override the default _filler_array_max_size so that no humongous filler
1959 // objects are created.
1960 _filler_array_max_size = _humongous_object_threshold_in_words;
1961
1962 uint n_queues = ParallelGCThreads;
1963 _task_queues = new RefToScanQueueSet(n_queues);
1964
1965 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1966 assert(n_rem_sets > 0, "Invariant.");
1967
1968 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1969 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1970 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1971
1972 for (uint i = 0; i < n_queues; i++) {
1973 RefToScanQueue* q = new RefToScanQueue();
1974 q->initialize();
1975 _task_queues->register_queue(i, q);
1976 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1977 }
1978 clear_cset_start_regions();
1979
1980 // Initialize the G1EvacuationFailureALot counters and flags.
1981 NOT_PRODUCT(reset_evacuation_should_fail();)
1982
1983 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1984 }
1985
1986 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1987 size_t size,
1988 size_t translation_factor) {
1989 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1990 // Allocate a new reserved space, preferring to use large pages.
1991 ReservedSpace rs(size, preferred_page_size);
1992 G1RegionToSpaceMapper* result =
1993 G1RegionToSpaceMapper::create_mapper(rs,
1994 size,
1995 rs.alignment(),
1996 HeapRegion::GrainBytes,
1997 translation_factor,
1998 mtGC);
1999 if (TracePageSizes) {
2000 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2001 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2002 }
2003 return result;
2004 }
2005
2006 jint G1CollectedHeap::initialize() {
2007 CollectedHeap::pre_initialize();
2008 os::enable_vtime();
2009
2010 G1Log::init();
2011
2012 // Necessary to satisfy locking discipline assertions.
2013
2014 MutexLocker x(Heap_lock);
2015
2016 // We have to initialize the printer before committing the heap, as
2017 // it will be used then.
2018 _hr_printer.set_active(G1PrintHeapRegions);
2019
2020 // While there are no constraints in the GC code that HeapWordSize
2021 // be any particular value, there are multiple other areas in the
2022 // system which believe this to be true (e.g. oop->object_size in some
2023 // cases incorrectly returns the size in wordSize units rather than
2024 // HeapWordSize).
2025 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2026
2027 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2028 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2029 size_t heap_alignment = collector_policy()->heap_alignment();
2030
2031 // Ensure that the sizes are properly aligned.
2032 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2033 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2034 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2035
2036 _refine_cte_cl = new RefineCardTableEntryClosure();
2037
2038 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2039
2040 // Reserve the maximum.
2041
2042 // When compressed oops are enabled, the preferred heap base
2043 // is calculated by subtracting the requested size from the
2044 // 32Gb boundary and using the result as the base address for
2045 // heap reservation. If the requested size is not aligned to
2046 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2047 // into the ReservedHeapSpace constructor) then the actual
2048 // base of the reserved heap may end up differing from the
2049 // address that was requested (i.e. the preferred heap base).
2050 // If this happens then we could end up using a non-optimal
2051 // compressed oops mode.
2052
2053 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2054 heap_alignment);
2055
2056 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2057
2058 // Create the barrier set for the entire reserved region.
2059 G1SATBCardTableLoggingModRefBS* bs
2060 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2061 bs->initialize();
2062 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2063 set_barrier_set(bs);
2064
2065 // Also create a G1 rem set.
2066 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2067
2068 // Carve out the G1 part of the heap.
2069
2070 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2071 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2072 G1RegionToSpaceMapper* heap_storage =
2073 G1RegionToSpaceMapper::create_mapper(g1_rs,
2074 g1_rs.size(),
2075 page_size,
2076 HeapRegion::GrainBytes,
2077 1,
2078 mtJavaHeap);
2079 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2080 max_byte_size, page_size,
2081 heap_rs.base(),
2082 heap_rs.size());
2083 heap_storage->set_mapping_changed_listener(&_listener);
2084
2085 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2086 G1RegionToSpaceMapper* bot_storage =
2087 create_aux_memory_mapper("Block offset table",
2088 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2089 G1BlockOffsetSharedArray::heap_map_factor());
2090
2091 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2092 G1RegionToSpaceMapper* cardtable_storage =
2093 create_aux_memory_mapper("Card table",
2094 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2095 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2096
2097 G1RegionToSpaceMapper* card_counts_storage =
2098 create_aux_memory_mapper("Card counts table",
2099 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2100 G1CardCounts::heap_map_factor());
2101
2102 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2103 G1RegionToSpaceMapper* prev_bitmap_storage =
2104 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2105 G1RegionToSpaceMapper* next_bitmap_storage =
2106 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2107
2108 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2109 g1_barrier_set()->initialize(cardtable_storage);
2110 // Do later initialization work for concurrent refinement.
2111 _cg1r->init(card_counts_storage);
2112
2113 // 6843694 - ensure that the maximum region index can fit
2114 // in the remembered set structures.
2115 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2116 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2117
2118 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2119 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2120 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2121 "too many cards per region");
2122
2123 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2124
2125 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2126
2127 {
2128 HeapWord* start = _hrm.reserved().start();
2129 HeapWord* end = _hrm.reserved().end();
2130 size_t granularity = HeapRegion::GrainBytes;
2131
2132 _in_cset_fast_test.initialize(start, end, granularity);
2133 _humongous_reclaim_candidates.initialize(start, end, granularity);
2134 }
2135
2136 // Create the ConcurrentMark data structure and thread.
2137 // (Must do this late, so that "max_regions" is defined.)
2138 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2139 if (_cm == NULL || !_cm->completed_initialization()) {
2140 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2141 return JNI_ENOMEM;
2142 }
2143 _cmThread = _cm->cmThread();
2144
2145 // Initialize the from_card cache structure of HeapRegionRemSet.
2146 HeapRegionRemSet::init_heap(max_regions());
2147
2148 // Now expand into the initial heap size.
2149 if (!expand(init_byte_size)) {
2150 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2151 return JNI_ENOMEM;
2152 }
2153
2154 // Perform any initialization actions delegated to the policy.
2155 g1_policy()->init();
2156
2157 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2158 SATB_Q_FL_lock,
2159 G1SATBProcessCompletedThreshold,
2160 Shared_SATB_Q_lock);
2161
2162 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2163 DirtyCardQ_CBL_mon,
2164 DirtyCardQ_FL_lock,
2165 concurrent_g1_refine()->yellow_zone(),
2166 concurrent_g1_refine()->red_zone(),
2167 Shared_DirtyCardQ_lock);
2168
2169 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2170 DirtyCardQ_CBL_mon,
2171 DirtyCardQ_FL_lock,
2172 -1, // never trigger processing
2173 -1, // no limit on length
2174 Shared_DirtyCardQ_lock,
2175 &JavaThread::dirty_card_queue_set());
2176
2177 // Initialize the card queue set used to hold cards containing
2178 // references into the collection set.
2179 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2180 DirtyCardQ_CBL_mon,
2181 DirtyCardQ_FL_lock,
2182 -1, // never trigger processing
2183 -1, // no limit on length
2184 Shared_DirtyCardQ_lock,
2185 &JavaThread::dirty_card_queue_set());
2186
2187 // Here we allocate the dummy HeapRegion that is required by the
2188 // G1AllocRegion class.
2189 HeapRegion* dummy_region = _hrm.get_dummy_region();
2190
2191 // We'll re-use the same region whether the alloc region will
2192 // require BOT updates or not and, if it doesn't, then a non-young
2193 // region will complain that it cannot support allocations without
2194 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2195 dummy_region->set_eden();
2196 // Make sure it's full.
2197 dummy_region->set_top(dummy_region->end());
2198 G1AllocRegion::setup(this, dummy_region);
2199
2200 _allocator->init_mutator_alloc_region();
2201
2202 // Do create of the monitoring and management support so that
2203 // values in the heap have been properly initialized.
2204 _g1mm = new G1MonitoringSupport(this);
2205
2206 G1StringDedup::initialize();
2207
2208 return JNI_OK;
2209 }
2210
2211 void G1CollectedHeap::stop() {
2212 // Stop all concurrent threads. We do this to make sure these threads
2213 // do not continue to execute and access resources (e.g. gclog_or_tty)
2214 // that are destroyed during shutdown.
2215 _cg1r->stop();
2216 _cmThread->stop();
2217 if (G1StringDedup::is_enabled()) {
2218 G1StringDedup::stop();
2219 }
2220 }
2221
2222 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2223 return HeapRegion::max_region_size();
2224 }
2225
2226 void G1CollectedHeap::post_initialize() {
2227 CollectedHeap::post_initialize();
2228 ref_processing_init();
2229 }
2230
2231 void G1CollectedHeap::ref_processing_init() {
2232 // Reference processing in G1 currently works as follows:
2233 //
2234 // * There are two reference processor instances. One is
2235 // used to record and process discovered references
2236 // during concurrent marking; the other is used to
2237 // record and process references during STW pauses
2238 // (both full and incremental).
2239 // * Both ref processors need to 'span' the entire heap as
2240 // the regions in the collection set may be dotted around.
2241 //
2242 // * For the concurrent marking ref processor:
2243 // * Reference discovery is enabled at initial marking.
2244 // * Reference discovery is disabled and the discovered
2245 // references processed etc during remarking.
2246 // * Reference discovery is MT (see below).
2247 // * Reference discovery requires a barrier (see below).
2248 // * Reference processing may or may not be MT
2249 // (depending on the value of ParallelRefProcEnabled
2250 // and ParallelGCThreads).
2251 // * A full GC disables reference discovery by the CM
2252 // ref processor and abandons any entries on it's
2253 // discovered lists.
2254 //
2255 // * For the STW processor:
2256 // * Non MT discovery is enabled at the start of a full GC.
2257 // * Processing and enqueueing during a full GC is non-MT.
2258 // * During a full GC, references are processed after marking.
2259 //
2260 // * Discovery (may or may not be MT) is enabled at the start
2261 // of an incremental evacuation pause.
2262 // * References are processed near the end of a STW evacuation pause.
2263 // * For both types of GC:
2264 // * Discovery is atomic - i.e. not concurrent.
2265 // * Reference discovery will not need a barrier.
2266
2267 MemRegion mr = reserved_region();
2268
2269 // Concurrent Mark ref processor
2270 _ref_processor_cm =
2271 new ReferenceProcessor(mr, // span
2272 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2273 // mt processing
2274 ParallelGCThreads,
2275 // degree of mt processing
2276 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2277 // mt discovery
2278 MAX2(ParallelGCThreads, ConcGCThreads),
2279 // degree of mt discovery
2280 false,
2281 // Reference discovery is not atomic
2282 &_is_alive_closure_cm);
2283 // is alive closure
2284 // (for efficiency/performance)
2285
2286 // STW ref processor
2287 _ref_processor_stw =
2288 new ReferenceProcessor(mr, // span
2289 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2290 // mt processing
2291 ParallelGCThreads,
2292 // degree of mt processing
2293 (ParallelGCThreads > 1),
2294 // mt discovery
2295 ParallelGCThreads,
2296 // degree of mt discovery
2297 true,
2298 // Reference discovery is atomic
2299 &_is_alive_closure_stw);
2300 // is alive closure
2301 // (for efficiency/performance)
2302 }
2303
2304 size_t G1CollectedHeap::capacity() const {
2305 return _hrm.length() * HeapRegion::GrainBytes;
2306 }
2307
2308 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2309 assert(!hr->is_continues_humongous(), "pre-condition");
2310 hr->reset_gc_time_stamp();
2311 if (hr->is_starts_humongous()) {
2312 uint first_index = hr->hrm_index() + 1;
2313 uint last_index = hr->last_hc_index();
2314 for (uint i = first_index; i < last_index; i += 1) {
2315 HeapRegion* chr = region_at(i);
2316 assert(chr->is_continues_humongous(), "sanity");
2317 chr->reset_gc_time_stamp();
2318 }
2319 }
2320 }
2321
2322 #ifndef PRODUCT
2323
2324 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2325 private:
2326 unsigned _gc_time_stamp;
2327 bool _failures;
2328
2329 public:
2330 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2331 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2332
2333 virtual bool doHeapRegion(HeapRegion* hr) {
2334 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2335 if (_gc_time_stamp != region_gc_time_stamp) {
2336 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2337 "expected %d", HR_FORMAT_PARAMS(hr),
2338 region_gc_time_stamp, _gc_time_stamp);
2339 _failures = true;
2340 }
2341 return false;
2342 }
2343
2344 bool failures() { return _failures; }
2345 };
2346
2347 void G1CollectedHeap::check_gc_time_stamps() {
2348 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2349 heap_region_iterate(&cl);
2350 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2351 }
2352 #endif // PRODUCT
2353
2354 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2355 DirtyCardQueue* into_cset_dcq,
2356 bool concurrent,
2357 uint worker_i) {
2358 // Clean cards in the hot card cache
2359 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2360 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2361
2362 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2363 size_t n_completed_buffers = 0;
2364 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2365 n_completed_buffers++;
2366 }
2367 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2368 dcqs.clear_n_completed_buffers();
2369 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2370 }
2371
2372
2373 // Computes the sum of the storage used by the various regions.
2374 size_t G1CollectedHeap::used() const {
2375 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2376 if (_archive_allocator != NULL) {
2377 result += _archive_allocator->used();
2378 }
2379 return result;
2380 }
2381
2382 size_t G1CollectedHeap::used_unlocked() const {
2383 return _summary_bytes_used;
2384 }
2385
2386 class SumUsedClosure: public HeapRegionClosure {
2387 size_t _used;
2388 public:
2389 SumUsedClosure() : _used(0) {}
2390 bool doHeapRegion(HeapRegion* r) {
2391 if (!r->is_continues_humongous()) {
2392 _used += r->used();
2393 }
2394 return false;
2395 }
2396 size_t result() { return _used; }
2397 };
2398
2399 size_t G1CollectedHeap::recalculate_used() const {
2400 double recalculate_used_start = os::elapsedTime();
2401
2402 SumUsedClosure blk;
2403 heap_region_iterate(&blk);
2404
2405 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2406 return blk.result();
2407 }
2408
2409 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2410 switch (cause) {
2411 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2412 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2413 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2414 case GCCause::_g1_humongous_allocation: return true;
2415 case GCCause::_update_allocation_context_stats_inc: return true;
2416 case GCCause::_wb_conc_mark: return true;
2417 default: return false;
2418 }
2419 }
2420
2421 #ifndef PRODUCT
2422 void G1CollectedHeap::allocate_dummy_regions() {
2423 // Let's fill up most of the region
2424 size_t word_size = HeapRegion::GrainWords - 1024;
2425 // And as a result the region we'll allocate will be humongous.
2426 guarantee(is_humongous(word_size), "sanity");
2427
2428 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2429 // Let's use the existing mechanism for the allocation
2430 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2431 AllocationContext::system());
2432 if (dummy_obj != NULL) {
2433 MemRegion mr(dummy_obj, word_size);
2434 CollectedHeap::fill_with_object(mr);
2435 } else {
2436 // If we can't allocate once, we probably cannot allocate
2437 // again. Let's get out of the loop.
2438 break;
2439 }
2440 }
2441 }
2442 #endif // !PRODUCT
2443
2444 void G1CollectedHeap::increment_old_marking_cycles_started() {
2445 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2446 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2447 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2448 _old_marking_cycles_started, _old_marking_cycles_completed));
2449
2450 _old_marking_cycles_started++;
2451 }
2452
2453 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2454 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2455
2456 // We assume that if concurrent == true, then the caller is a
2457 // concurrent thread that was joined the Suspendible Thread
2458 // Set. If there's ever a cheap way to check this, we should add an
2459 // assert here.
2460
2461 // Given that this method is called at the end of a Full GC or of a
2462 // concurrent cycle, and those can be nested (i.e., a Full GC can
2463 // interrupt a concurrent cycle), the number of full collections
2464 // completed should be either one (in the case where there was no
2465 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2466 // behind the number of full collections started.
2467
2468 // This is the case for the inner caller, i.e. a Full GC.
2469 assert(concurrent ||
2470 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2471 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2472 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2473 "is inconsistent with _old_marking_cycles_completed = %u",
2474 _old_marking_cycles_started, _old_marking_cycles_completed));
2475
2476 // This is the case for the outer caller, i.e. the concurrent cycle.
2477 assert(!concurrent ||
2478 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2479 err_msg("for outer caller (concurrent cycle): "
2480 "_old_marking_cycles_started = %u "
2481 "is inconsistent with _old_marking_cycles_completed = %u",
2482 _old_marking_cycles_started, _old_marking_cycles_completed));
2483
2484 _old_marking_cycles_completed += 1;
2485
2486 // We need to clear the "in_progress" flag in the CM thread before
2487 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2488 // is set) so that if a waiter requests another System.gc() it doesn't
2489 // incorrectly see that a marking cycle is still in progress.
2490 if (concurrent) {
2491 _cmThread->set_idle();
2492 }
2493
2494 // This notify_all() will ensure that a thread that called
2495 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2496 // and it's waiting for a full GC to finish will be woken up. It is
2497 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2498 FullGCCount_lock->notify_all();
2499 }
2500
2501 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2502 collector_state()->set_concurrent_cycle_started(true);
2503 _gc_timer_cm->register_gc_start(start_time);
2504
2505 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2506 trace_heap_before_gc(_gc_tracer_cm);
2507 }
2508
2509 void G1CollectedHeap::register_concurrent_cycle_end() {
2510 if (collector_state()->concurrent_cycle_started()) {
2511 if (_cm->has_aborted()) {
2512 _gc_tracer_cm->report_concurrent_mode_failure();
2513 }
2514
2515 _gc_timer_cm->register_gc_end();
2516 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2517
2518 // Clear state variables to prepare for the next concurrent cycle.
2519 collector_state()->set_concurrent_cycle_started(false);
2520 _heap_summary_sent = false;
2521 }
2522 }
2523
2524 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2525 if (collector_state()->concurrent_cycle_started()) {
2526 // This function can be called when:
2527 // the cleanup pause is run
2528 // the concurrent cycle is aborted before the cleanup pause.
2529 // the concurrent cycle is aborted after the cleanup pause,
2530 // but before the concurrent cycle end has been registered.
2531 // Make sure that we only send the heap information once.
2532 if (!_heap_summary_sent) {
2533 trace_heap_after_gc(_gc_tracer_cm);
2534 _heap_summary_sent = true;
2535 }
2536 }
2537 }
2538
2539 void G1CollectedHeap::collect(GCCause::Cause cause) {
2540 assert_heap_not_locked();
2541
2542 uint gc_count_before;
2543 uint old_marking_count_before;
2544 uint full_gc_count_before;
2545 bool retry_gc;
2546
2547 do {
2548 retry_gc = false;
2549
2550 {
2551 MutexLocker ml(Heap_lock);
2552
2553 // Read the GC count while holding the Heap_lock
2554 gc_count_before = total_collections();
2555 full_gc_count_before = total_full_collections();
2556 old_marking_count_before = _old_marking_cycles_started;
2557 }
2558
2559 if (should_do_concurrent_full_gc(cause)) {
2560 // Schedule an initial-mark evacuation pause that will start a
2561 // concurrent cycle. We're setting word_size to 0 which means that
2562 // we are not requesting a post-GC allocation.
2563 VM_G1IncCollectionPause op(gc_count_before,
2564 0, /* word_size */
2565 true, /* should_initiate_conc_mark */
2566 g1_policy()->max_pause_time_ms(),
2567 cause);
2568 op.set_allocation_context(AllocationContext::current());
2569
2570 VMThread::execute(&op);
2571 if (!op.pause_succeeded()) {
2572 if (old_marking_count_before == _old_marking_cycles_started) {
2573 retry_gc = op.should_retry_gc();
2574 } else {
2575 // A Full GC happened while we were trying to schedule the
2576 // initial-mark GC. No point in starting a new cycle given
2577 // that the whole heap was collected anyway.
2578 }
2579
2580 if (retry_gc) {
2581 if (GC_locker::is_active_and_needs_gc()) {
2582 GC_locker::stall_until_clear();
2583 }
2584 }
2585 }
2586 } else {
2587 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2588 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2589
2590 // Schedule a standard evacuation pause. We're setting word_size
2591 // to 0 which means that we are not requesting a post-GC allocation.
2592 VM_G1IncCollectionPause op(gc_count_before,
2593 0, /* word_size */
2594 false, /* should_initiate_conc_mark */
2595 g1_policy()->max_pause_time_ms(),
2596 cause);
2597 VMThread::execute(&op);
2598 } else {
2599 // Schedule a Full GC.
2600 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2601 VMThread::execute(&op);
2602 }
2603 }
2604 } while (retry_gc);
2605 }
2606
2607 bool G1CollectedHeap::is_in(const void* p) const {
2608 if (_hrm.reserved().contains(p)) {
2609 // Given that we know that p is in the reserved space,
2610 // heap_region_containing_raw() should successfully
2611 // return the containing region.
2612 HeapRegion* hr = heap_region_containing_raw(p);
2613 return hr->is_in(p);
2614 } else {
2615 return false;
2616 }
2617 }
2618
2619 #ifdef ASSERT
2620 bool G1CollectedHeap::is_in_exact(const void* p) const {
2621 bool contains = reserved_region().contains(p);
2622 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2623 if (contains && available) {
2624 return true;
2625 } else {
2626 return false;
2627 }
2628 }
2629 #endif
2630
2631 // Iteration functions.
2632
2633 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2634
2635 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2636 ExtendedOopClosure* _cl;
2637 public:
2638 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2639 bool doHeapRegion(HeapRegion* r) {
2640 if (!r->is_continues_humongous()) {
2641 r->oop_iterate(_cl);
2642 }
2643 return false;
2644 }
2645 };
2646
2647 // Iterates an ObjectClosure over all objects within a HeapRegion.
2648
2649 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2650 ObjectClosure* _cl;
2651 public:
2652 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2653 bool doHeapRegion(HeapRegion* r) {
2654 if (!r->is_continues_humongous()) {
2655 r->object_iterate(_cl);
2656 }
2657 return false;
2658 }
2659 };
2660
2661 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2662 IterateObjectClosureRegionClosure blk(cl);
2663 heap_region_iterate(&blk);
2664 }
2665
2666 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2667 _hrm.iterate(cl);
2668 }
2669
2670 void
2671 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2672 uint worker_id,
2673 HeapRegionClaimer *hrclaimer,
2674 bool concurrent) const {
2675 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2676 }
2677
2678 // Clear the cached CSet starting regions and (more importantly)
2679 // the time stamps. Called when we reset the GC time stamp.
2680 void G1CollectedHeap::clear_cset_start_regions() {
2681 assert(_worker_cset_start_region != NULL, "sanity");
2682 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2683
2684 for (uint i = 0; i < ParallelGCThreads; i++) {
2685 _worker_cset_start_region[i] = NULL;
2686 _worker_cset_start_region_time_stamp[i] = 0;
2687 }
2688 }
2689
2690 // Given the id of a worker, obtain or calculate a suitable
2691 // starting region for iterating over the current collection set.
2692 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2693 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2694
2695 HeapRegion* result = NULL;
2696 unsigned gc_time_stamp = get_gc_time_stamp();
2697
2698 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2699 // Cached starting region for current worker was set
2700 // during the current pause - so it's valid.
2701 // Note: the cached starting heap region may be NULL
2702 // (when the collection set is empty).
2703 result = _worker_cset_start_region[worker_i];
2704 assert(result == NULL || result->in_collection_set(), "sanity");
2705 return result;
2706 }
2707
2708 // The cached entry was not valid so let's calculate
2709 // a suitable starting heap region for this worker.
2710
2711 // We want the parallel threads to start their collection
2712 // set iteration at different collection set regions to
2713 // avoid contention.
2714 // If we have:
2715 // n collection set regions
2716 // p threads
2717 // Then thread t will start at region floor ((t * n) / p)
2718
2719 result = g1_policy()->collection_set();
2720 uint cs_size = g1_policy()->cset_region_length();
2721 uint active_workers = workers()->active_workers();
2722
2723 uint end_ind = (cs_size * worker_i) / active_workers;
2724 uint start_ind = 0;
2725
2726 if (worker_i > 0 &&
2727 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2728 // Previous workers starting region is valid
2729 // so let's iterate from there
2730 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2731 result = _worker_cset_start_region[worker_i - 1];
2732 }
2733
2734 for (uint i = start_ind; i < end_ind; i++) {
2735 result = result->next_in_collection_set();
2736 }
2737
2738 // Note: the calculated starting heap region may be NULL
2739 // (when the collection set is empty).
2740 assert(result == NULL || result->in_collection_set(), "sanity");
2741 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2742 "should be updated only once per pause");
2743 _worker_cset_start_region[worker_i] = result;
2744 OrderAccess::storestore();
2745 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2746 return result;
2747 }
2748
2749 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2750 HeapRegion* r = g1_policy()->collection_set();
2751 while (r != NULL) {
2752 HeapRegion* next = r->next_in_collection_set();
2753 if (cl->doHeapRegion(r)) {
2754 cl->incomplete();
2755 return;
2756 }
2757 r = next;
2758 }
2759 }
2760
2761 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2762 HeapRegionClosure *cl) {
2763 if (r == NULL) {
2764 // The CSet is empty so there's nothing to do.
2765 return;
2766 }
2767
2768 assert(r->in_collection_set(),
2769 "Start region must be a member of the collection set.");
2770 HeapRegion* cur = r;
2771 while (cur != NULL) {
2772 HeapRegion* next = cur->next_in_collection_set();
2773 if (cl->doHeapRegion(cur) && false) {
2774 cl->incomplete();
2775 return;
2776 }
2777 cur = next;
2778 }
2779 cur = g1_policy()->collection_set();
2780 while (cur != r) {
2781 HeapRegion* next = cur->next_in_collection_set();
2782 if (cl->doHeapRegion(cur) && false) {
2783 cl->incomplete();
2784 return;
2785 }
2786 cur = next;
2787 }
2788 }
2789
2790 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2791 HeapRegion* result = _hrm.next_region_in_heap(from);
2792 while (result != NULL && result->is_pinned()) {
2793 result = _hrm.next_region_in_heap(result);
2794 }
2795 return result;
2796 }
2797
2798 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2799 HeapRegion* hr = heap_region_containing(addr);
2800 return hr->block_start(addr);
2801 }
2802
2803 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2804 HeapRegion* hr = heap_region_containing(addr);
2805 return hr->block_size(addr);
2806 }
2807
2808 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2809 HeapRegion* hr = heap_region_containing(addr);
2810 return hr->block_is_obj(addr);
2811 }
2812
2813 bool G1CollectedHeap::supports_tlab_allocation() const {
2814 return true;
2815 }
2816
2817 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2818 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2819 }
2820
2821 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2822 return young_list()->eden_used_bytes();
2823 }
2824
2825 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2826 // must be smaller than the humongous object limit.
2827 size_t G1CollectedHeap::max_tlab_size() const {
2828 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2829 }
2830
2831 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2832 // Return the remaining space in the cur alloc region, but not less than
2833 // the min TLAB size.
2834
2835 // Also, this value can be at most the humongous object threshold,
2836 // since we can't allow tlabs to grow big enough to accommodate
2837 // humongous objects.
2838
2839 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2840 size_t max_tlab = max_tlab_size() * wordSize;
2841 if (hr == NULL) {
2842 return max_tlab;
2843 } else {
2844 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2845 }
2846 }
2847
2848 size_t G1CollectedHeap::max_capacity() const {
2849 return _hrm.reserved().byte_size();
2850 }
2851
2852 jlong G1CollectedHeap::millis_since_last_gc() {
2853 // assert(false, "NYI");
2854 return 0;
2855 }
2856
2857 void G1CollectedHeap::prepare_for_verify() {
2858 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2859 ensure_parsability(false);
2860 }
2861 g1_rem_set()->prepare_for_verify();
2862 }
2863
2864 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2865 VerifyOption vo) {
2866 switch (vo) {
2867 case VerifyOption_G1UsePrevMarking:
2868 return hr->obj_allocated_since_prev_marking(obj);
2869 case VerifyOption_G1UseNextMarking:
2870 return hr->obj_allocated_since_next_marking(obj);
2871 case VerifyOption_G1UseMarkWord:
2872 return false;
2873 default:
2874 ShouldNotReachHere();
2875 }
2876 return false; // keep some compilers happy
2877 }
2878
2879 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2880 switch (vo) {
2881 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2882 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2883 case VerifyOption_G1UseMarkWord: return NULL;
2884 default: ShouldNotReachHere();
2885 }
2886 return NULL; // keep some compilers happy
2887 }
2888
2889 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2890 switch (vo) {
2891 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2892 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2893 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2894 default: ShouldNotReachHere();
2895 }
2896 return false; // keep some compilers happy
2897 }
2898
2899 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2900 switch (vo) {
2901 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2902 case VerifyOption_G1UseNextMarking: return "NTAMS";
2903 case VerifyOption_G1UseMarkWord: return "NONE";
2904 default: ShouldNotReachHere();
2905 }
2906 return NULL; // keep some compilers happy
2907 }
2908
2909 class VerifyRootsClosure: public OopClosure {
2910 private:
2911 G1CollectedHeap* _g1h;
2912 VerifyOption _vo;
2913 bool _failures;
2914 public:
2915 // _vo == UsePrevMarking -> use "prev" marking information,
2916 // _vo == UseNextMarking -> use "next" marking information,
2917 // _vo == UseMarkWord -> use mark word from object header.
2918 VerifyRootsClosure(VerifyOption vo) :
2919 _g1h(G1CollectedHeap::heap()),
2920 _vo(vo),
2921 _failures(false) { }
2922
2923 bool failures() { return _failures; }
2924
2925 template <class T> void do_oop_nv(T* p) {
2926 T heap_oop = oopDesc::load_heap_oop(p);
2927 if (!oopDesc::is_null(heap_oop)) {
2928 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2929 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2930 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2931 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2932 if (_vo == VerifyOption_G1UseMarkWord) {
2933 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2934 }
2935 obj->print_on(gclog_or_tty);
2936 _failures = true;
2937 }
2938 }
2939 }
2940
2941 void do_oop(oop* p) { do_oop_nv(p); }
2942 void do_oop(narrowOop* p) { do_oop_nv(p); }
2943 };
2944
2945 class G1VerifyCodeRootOopClosure: public OopClosure {
2946 G1CollectedHeap* _g1h;
2947 OopClosure* _root_cl;
2948 nmethod* _nm;
2949 VerifyOption _vo;
2950 bool _failures;
2951
2952 template <class T> void do_oop_work(T* p) {
2953 // First verify that this root is live
2954 _root_cl->do_oop(p);
2955
2956 if (!G1VerifyHeapRegionCodeRoots) {
2957 // We're not verifying the code roots attached to heap region.
2958 return;
2959 }
2960
2961 // Don't check the code roots during marking verification in a full GC
2962 if (_vo == VerifyOption_G1UseMarkWord) {
2963 return;
2964 }
2965
2966 // Now verify that the current nmethod (which contains p) is
2967 // in the code root list of the heap region containing the
2968 // object referenced by p.
2969
2970 T heap_oop = oopDesc::load_heap_oop(p);
2971 if (!oopDesc::is_null(heap_oop)) {
2972 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2973
2974 // Now fetch the region containing the object
2975 HeapRegion* hr = _g1h->heap_region_containing(obj);
2976 HeapRegionRemSet* hrrs = hr->rem_set();
2977 // Verify that the strong code root list for this region
2978 // contains the nmethod
2979 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2980 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2981 "from nmethod " PTR_FORMAT " not in strong "
2982 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2983 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2984 _failures = true;
2985 }
2986 }
2987 }
2988
2989 public:
2990 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2991 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2992
2993 void do_oop(oop* p) { do_oop_work(p); }
2994 void do_oop(narrowOop* p) { do_oop_work(p); }
2995
2996 void set_nmethod(nmethod* nm) { _nm = nm; }
2997 bool failures() { return _failures; }
2998 };
2999
3000 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3001 G1VerifyCodeRootOopClosure* _oop_cl;
3002
3003 public:
3004 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3005 _oop_cl(oop_cl) {}
3006
3007 void do_code_blob(CodeBlob* cb) {
3008 nmethod* nm = cb->as_nmethod_or_null();
3009 if (nm != NULL) {
3010 _oop_cl->set_nmethod(nm);
3011 nm->oops_do(_oop_cl);
3012 }
3013 }
3014 };
3015
3016 class YoungRefCounterClosure : public OopClosure {
3017 G1CollectedHeap* _g1h;
3018 int _count;
3019 public:
3020 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3021 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3022 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3023
3024 int count() { return _count; }
3025 void reset_count() { _count = 0; };
3026 };
3027
3028 class VerifyKlassClosure: public KlassClosure {
3029 YoungRefCounterClosure _young_ref_counter_closure;
3030 OopClosure *_oop_closure;
3031 public:
3032 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3033 void do_klass(Klass* k) {
3034 k->oops_do(_oop_closure);
3035
3036 _young_ref_counter_closure.reset_count();
3037 k->oops_do(&_young_ref_counter_closure);
3038 if (_young_ref_counter_closure.count() > 0) {
3039 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3040 }
3041 }
3042 };
3043
3044 class VerifyLivenessOopClosure: public OopClosure {
3045 G1CollectedHeap* _g1h;
3046 VerifyOption _vo;
3047 public:
3048 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3049 _g1h(g1h), _vo(vo)
3050 { }
3051 void do_oop(narrowOop *p) { do_oop_work(p); }
3052 void do_oop( oop *p) { do_oop_work(p); }
3053
3054 template <class T> void do_oop_work(T *p) {
3055 oop obj = oopDesc::load_decode_heap_oop(p);
3056 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3057 "Dead object referenced by a not dead object");
3058 }
3059 };
3060
3061 class VerifyObjsInRegionClosure: public ObjectClosure {
3062 private:
3063 G1CollectedHeap* _g1h;
3064 size_t _live_bytes;
3065 HeapRegion *_hr;
3066 VerifyOption _vo;
3067 public:
3068 // _vo == UsePrevMarking -> use "prev" marking information,
3069 // _vo == UseNextMarking -> use "next" marking information,
3070 // _vo == UseMarkWord -> use mark word from object header.
3071 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3072 : _live_bytes(0), _hr(hr), _vo(vo) {
3073 _g1h = G1CollectedHeap::heap();
3074 }
3075 void do_object(oop o) {
3076 VerifyLivenessOopClosure isLive(_g1h, _vo);
3077 assert(o != NULL, "Huh?");
3078 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3079 // If the object is alive according to the mark word,
3080 // then verify that the marking information agrees.
3081 // Note we can't verify the contra-positive of the
3082 // above: if the object is dead (according to the mark
3083 // word), it may not be marked, or may have been marked
3084 // but has since became dead, or may have been allocated
3085 // since the last marking.
3086 if (_vo == VerifyOption_G1UseMarkWord) {
3087 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3088 }
3089
3090 o->oop_iterate_no_header(&isLive);
3091 if (!_hr->obj_allocated_since_prev_marking(o)) {
3092 size_t obj_size = o->size(); // Make sure we don't overflow
3093 _live_bytes += (obj_size * HeapWordSize);
3094 }
3095 }
3096 }
3097 size_t live_bytes() { return _live_bytes; }
3098 };
3099
3100 class VerifyArchiveOopClosure: public OopClosure {
3101 public:
3102 VerifyArchiveOopClosure(HeapRegion *hr) { }
3103 void do_oop(narrowOop *p) { do_oop_work(p); }
3104 void do_oop( oop *p) { do_oop_work(p); }
3105
3106 template <class T> void do_oop_work(T *p) {
3107 oop obj = oopDesc::load_decode_heap_oop(p);
3108 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3109 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3110 p2i(p), p2i(obj)));
3111 }
3112 };
3113
3114 class VerifyArchiveRegionClosure: public ObjectClosure {
3115 public:
3116 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3117 // Verify that all object pointers are to archive regions.
3118 void do_object(oop o) {
3119 VerifyArchiveOopClosure checkOop(NULL);
3120 assert(o != NULL, "Should not be here for NULL oops");
3121 o->oop_iterate_no_header(&checkOop);
3122 }
3123 };
3124
3125 class VerifyRegionClosure: public HeapRegionClosure {
3126 private:
3127 bool _par;
3128 VerifyOption _vo;
3129 bool _failures;
3130 public:
3131 // _vo == UsePrevMarking -> use "prev" marking information,
3132 // _vo == UseNextMarking -> use "next" marking information,
3133 // _vo == UseMarkWord -> use mark word from object header.
3134 VerifyRegionClosure(bool par, VerifyOption vo)
3135 : _par(par),
3136 _vo(vo),
3137 _failures(false) {}
3138
3139 bool failures() {
3140 return _failures;
3141 }
3142
3143 bool doHeapRegion(HeapRegion* r) {
3144 // For archive regions, verify there are no heap pointers to
3145 // non-pinned regions. For all others, verify liveness info.
3146 if (r->is_archive()) {
3147 VerifyArchiveRegionClosure verify_oop_pointers(r);
3148 r->object_iterate(&verify_oop_pointers);
3149 return true;
3150 }
3151 if (!r->is_continues_humongous()) {
3152 bool failures = false;
3153 r->verify(_vo, &failures);
3154 if (failures) {
3155 _failures = true;
3156 } else {
3157 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3158 r->object_iterate(¬_dead_yet_cl);
3159 if (_vo != VerifyOption_G1UseNextMarking) {
3160 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3161 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3162 "max_live_bytes " SIZE_FORMAT " "
3163 "< calculated " SIZE_FORMAT,
3164 p2i(r->bottom()), p2i(r->end()),
3165 r->max_live_bytes(),
3166 not_dead_yet_cl.live_bytes());
3167 _failures = true;
3168 }
3169 } else {
3170 // When vo == UseNextMarking we cannot currently do a sanity
3171 // check on the live bytes as the calculation has not been
3172 // finalized yet.
3173 }
3174 }
3175 }
3176 return false; // stop the region iteration if we hit a failure
3177 }
3178 };
3179
3180 // This is the task used for parallel verification of the heap regions
3181
3182 class G1ParVerifyTask: public AbstractGangTask {
3183 private:
3184 G1CollectedHeap* _g1h;
3185 VerifyOption _vo;
3186 bool _failures;
3187 HeapRegionClaimer _hrclaimer;
3188
3189 public:
3190 // _vo == UsePrevMarking -> use "prev" marking information,
3191 // _vo == UseNextMarking -> use "next" marking information,
3192 // _vo == UseMarkWord -> use mark word from object header.
3193 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3194 AbstractGangTask("Parallel verify task"),
3195 _g1h(g1h),
3196 _vo(vo),
3197 _failures(false),
3198 _hrclaimer(g1h->workers()->active_workers()) {}
3199
3200 bool failures() {
3201 return _failures;
3202 }
3203
3204 void work(uint worker_id) {
3205 HandleMark hm;
3206 VerifyRegionClosure blk(true, _vo);
3207 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3208 if (blk.failures()) {
3209 _failures = true;
3210 }
3211 }
3212 };
3213
3214 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3215 if (SafepointSynchronize::is_at_safepoint()) {
3216 assert(Thread::current()->is_VM_thread(),
3217 "Expected to be executed serially by the VM thread at this point");
3218
3219 if (!silent) { gclog_or_tty->print("Roots "); }
3220 VerifyRootsClosure rootsCl(vo);
3221 VerifyKlassClosure klassCl(this, &rootsCl);
3222 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3223
3224 // We apply the relevant closures to all the oops in the
3225 // system dictionary, class loader data graph, the string table
3226 // and the nmethods in the code cache.
3227 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3228 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3229
3230 {
3231 G1RootProcessor root_processor(this, 1);
3232 root_processor.process_all_roots(&rootsCl,
3233 &cldCl,
3234 &blobsCl);
3235 }
3236
3237 bool failures = rootsCl.failures() || codeRootsCl.failures();
3238
3239 if (vo != VerifyOption_G1UseMarkWord) {
3240 // If we're verifying during a full GC then the region sets
3241 // will have been torn down at the start of the GC. Therefore
3242 // verifying the region sets will fail. So we only verify
3243 // the region sets when not in a full GC.
3244 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3245 verify_region_sets();
3246 }
3247
3248 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3249 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3250
3251 G1ParVerifyTask task(this, vo);
3252 workers()->run_task(&task);
3253 if (task.failures()) {
3254 failures = true;
3255 }
3256
3257 } else {
3258 VerifyRegionClosure blk(false, vo);
3259 heap_region_iterate(&blk);
3260 if (blk.failures()) {
3261 failures = true;
3262 }
3263 }
3264
3265 if (G1StringDedup::is_enabled()) {
3266 if (!silent) gclog_or_tty->print("StrDedup ");
3267 G1StringDedup::verify();
3268 }
3269
3270 if (failures) {
3271 gclog_or_tty->print_cr("Heap:");
3272 // It helps to have the per-region information in the output to
3273 // help us track down what went wrong. This is why we call
3274 // print_extended_on() instead of print_on().
3275 print_extended_on(gclog_or_tty);
3276 gclog_or_tty->cr();
3277 gclog_or_tty->flush();
3278 }
3279 guarantee(!failures, "there should not have been any failures");
3280 } else {
3281 if (!silent) {
3282 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3283 if (G1StringDedup::is_enabled()) {
3284 gclog_or_tty->print(", StrDedup");
3285 }
3286 gclog_or_tty->print(") ");
3287 }
3288 }
3289 }
3290
3291 void G1CollectedHeap::verify(bool silent) {
3292 verify(silent, VerifyOption_G1UsePrevMarking);
3293 }
3294
3295 double G1CollectedHeap::verify(bool guard, const char* msg) {
3296 double verify_time_ms = 0.0;
3297
3298 if (guard && total_collections() >= VerifyGCStartAt) {
3299 double verify_start = os::elapsedTime();
3300 HandleMark hm; // Discard invalid handles created during verification
3301 prepare_for_verify();
3302 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3303 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3304 }
3305
3306 return verify_time_ms;
3307 }
3308
3309 void G1CollectedHeap::verify_before_gc() {
3310 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3311 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3312 }
3313
3314 void G1CollectedHeap::verify_after_gc() {
3315 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3316 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3317 }
3318
3319 class PrintRegionClosure: public HeapRegionClosure {
3320 outputStream* _st;
3321 public:
3322 PrintRegionClosure(outputStream* st) : _st(st) {}
3323 bool doHeapRegion(HeapRegion* r) {
3324 r->print_on(_st);
3325 return false;
3326 }
3327 };
3328
3329 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3330 const HeapRegion* hr,
3331 const VerifyOption vo) const {
3332 switch (vo) {
3333 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3334 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3335 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3336 default: ShouldNotReachHere();
3337 }
3338 return false; // keep some compilers happy
3339 }
3340
3341 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3342 const VerifyOption vo) const {
3343 switch (vo) {
3344 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3345 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3346 case VerifyOption_G1UseMarkWord: {
3347 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3348 return !obj->is_gc_marked() && !hr->is_archive();
3349 }
3350 default: ShouldNotReachHere();
3351 }
3352 return false; // keep some compilers happy
3353 }
3354
3355 void G1CollectedHeap::print_on(outputStream* st) const {
3356 st->print(" %-20s", "garbage-first heap");
3357 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3358 capacity()/K, used_unlocked()/K);
3359 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3360 p2i(_hrm.reserved().start()),
3361 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3362 p2i(_hrm.reserved().end()));
3363 st->cr();
3364 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3365 uint young_regions = _young_list->length();
3366 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3367 (size_t) young_regions * HeapRegion::GrainBytes / K);
3368 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3369 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3370 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3371 st->cr();
3372 MetaspaceAux::print_on(st);
3373 }
3374
3375 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3376 print_on(st);
3377
3378 // Print the per-region information.
3379 st->cr();
3380 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3381 "HS=humongous(starts), HC=humongous(continues), "
3382 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3383 "PTAMS=previous top-at-mark-start, "
3384 "NTAMS=next top-at-mark-start)");
3385 PrintRegionClosure blk(st);
3386 heap_region_iterate(&blk);
3387 }
3388
3389 void G1CollectedHeap::print_on_error(outputStream* st) const {
3390 this->CollectedHeap::print_on_error(st);
3391
3392 if (_cm != NULL) {
3393 st->cr();
3394 _cm->print_on_error(st);
3395 }
3396 }
3397
3398 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3399 workers()->print_worker_threads_on(st);
3400 _cmThread->print_on(st);
3401 st->cr();
3402 _cm->print_worker_threads_on(st);
3403 _cg1r->print_worker_threads_on(st);
3404 if (G1StringDedup::is_enabled()) {
3405 G1StringDedup::print_worker_threads_on(st);
3406 }
3407 }
3408
3409 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3410 workers()->threads_do(tc);
3411 tc->do_thread(_cmThread);
3412 _cg1r->threads_do(tc);
3413 if (G1StringDedup::is_enabled()) {
3414 G1StringDedup::threads_do(tc);
3415 }
3416 }
3417
3418 void G1CollectedHeap::print_tracing_info() const {
3419 // We'll overload this to mean "trace GC pause statistics."
3420 if (TraceYoungGenTime || TraceOldGenTime) {
3421 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3422 // to that.
3423 g1_policy()->print_tracing_info();
3424 }
3425 if (G1SummarizeRSetStats) {
3426 g1_rem_set()->print_summary_info();
3427 }
3428 if (G1SummarizeConcMark) {
3429 concurrent_mark()->print_summary_info();
3430 }
3431 g1_policy()->print_yg_surv_rate_info();
3432 }
3433
3434 #ifndef PRODUCT
3435 // Helpful for debugging RSet issues.
3436
3437 class PrintRSetsClosure : public HeapRegionClosure {
3438 private:
3439 const char* _msg;
3440 size_t _occupied_sum;
3441
3442 public:
3443 bool doHeapRegion(HeapRegion* r) {
3444 HeapRegionRemSet* hrrs = r->rem_set();
3445 size_t occupied = hrrs->occupied();
3446 _occupied_sum += occupied;
3447
3448 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3449 HR_FORMAT_PARAMS(r));
3450 if (occupied == 0) {
3451 gclog_or_tty->print_cr(" RSet is empty");
3452 } else {
3453 hrrs->print();
3454 }
3455 gclog_or_tty->print_cr("----------");
3456 return false;
3457 }
3458
3459 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3460 gclog_or_tty->cr();
3461 gclog_or_tty->print_cr("========================================");
3462 gclog_or_tty->print_cr("%s", msg);
3463 gclog_or_tty->cr();
3464 }
3465
3466 ~PrintRSetsClosure() {
3467 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3468 gclog_or_tty->print_cr("========================================");
3469 gclog_or_tty->cr();
3470 }
3471 };
3472
3473 void G1CollectedHeap::print_cset_rsets() {
3474 PrintRSetsClosure cl("Printing CSet RSets");
3475 collection_set_iterate(&cl);
3476 }
3477
3478 void G1CollectedHeap::print_all_rsets() {
3479 PrintRSetsClosure cl("Printing All RSets");;
3480 heap_region_iterate(&cl);
3481 }
3482 #endif // PRODUCT
3483
3484 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3485 YoungList* young_list = heap()->young_list();
3486
3487 size_t eden_used_bytes = young_list->eden_used_bytes();
3488 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3489
3490 size_t eden_capacity_bytes =
3491 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3492
3493 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3494 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3495 }
3496
3497 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3498 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3499 gc_tracer->report_gc_heap_summary(when, heap_summary);
3500
3501 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3502 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3503 }
3504
3505
3506 G1CollectedHeap* G1CollectedHeap::heap() {
3507 CollectedHeap* heap = Universe::heap();
3508 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3509 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3510 return (G1CollectedHeap*)heap;
3511 }
3512
3513 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3514 // always_do_update_barrier = false;
3515 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3516 // Fill TLAB's and such
3517 accumulate_statistics_all_tlabs();
3518 ensure_parsability(true);
3519
3520 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3521 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3522 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3523 }
3524 }
3525
3526 void G1CollectedHeap::gc_epilogue(bool full) {
3527
3528 if (G1SummarizeRSetStats &&
3529 (G1SummarizeRSetStatsPeriod > 0) &&
3530 // we are at the end of the GC. Total collections has already been increased.
3531 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3532 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3533 }
3534
3535 // FIXME: what is this about?
3536 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3537 // is set.
3538 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3539 "derived pointer present"));
3540 // always_do_update_barrier = true;
3541
3542 resize_all_tlabs();
3543 allocation_context_stats().update(full);
3544
3545 // We have just completed a GC. Update the soft reference
3546 // policy with the new heap occupancy
3547 Universe::update_heap_info_at_gc();
3548 }
3549
3550 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3551 uint gc_count_before,
3552 bool* succeeded,
3553 GCCause::Cause gc_cause) {
3554 assert_heap_not_locked_and_not_at_safepoint();
3555 g1_policy()->record_stop_world_start();
3556 VM_G1IncCollectionPause op(gc_count_before,
3557 word_size,
3558 false, /* should_initiate_conc_mark */
3559 g1_policy()->max_pause_time_ms(),
3560 gc_cause);
3561
3562 op.set_allocation_context(AllocationContext::current());
3563 VMThread::execute(&op);
3564
3565 HeapWord* result = op.result();
3566 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3567 assert(result == NULL || ret_succeeded,
3568 "the result should be NULL if the VM did not succeed");
3569 *succeeded = ret_succeeded;
3570
3571 assert_heap_not_locked();
3572 return result;
3573 }
3574
3575 void
3576 G1CollectedHeap::doConcurrentMark() {
3577 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3578 if (!_cmThread->in_progress()) {
3579 _cmThread->set_started();
3580 CGC_lock->notify();
3581 }
3582 }
3583
3584 size_t G1CollectedHeap::pending_card_num() {
3585 size_t extra_cards = 0;
3586 JavaThread *curr = Threads::first();
3587 while (curr != NULL) {
3588 DirtyCardQueue& dcq = curr->dirty_card_queue();
3589 extra_cards += dcq.size();
3590 curr = curr->next();
3591 }
3592 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3593 size_t buffer_size = dcqs.buffer_size();
3594 size_t buffer_num = dcqs.completed_buffers_num();
3595
3596 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3597 // in bytes - not the number of 'entries'. We need to convert
3598 // into a number of cards.
3599 return (buffer_size * buffer_num + extra_cards) / oopSize;
3600 }
3601
3602 size_t G1CollectedHeap::cards_scanned() {
3603 return g1_rem_set()->cardsScanned();
3604 }
3605
3606 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3607 private:
3608 size_t _total_humongous;
3609 size_t _candidate_humongous;
3610
3611 DirtyCardQueue _dcq;
3612
3613 // We don't nominate objects with many remembered set entries, on
3614 // the assumption that such objects are likely still live.
3615 bool is_remset_small(HeapRegion* region) const {
3616 HeapRegionRemSet* const rset = region->rem_set();
3617 return G1EagerReclaimHumongousObjectsWithStaleRefs
3618 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3619 : rset->is_empty();
3620 }
3621
3622 bool is_typeArray_region(HeapRegion* region) const {
3623 return oop(region->bottom())->is_typeArray();
3624 }
3625
3626 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3627 assert(region->is_starts_humongous(), "Must start a humongous object");
3628
3629 // Candidate selection must satisfy the following constraints
3630 // while concurrent marking is in progress:
3631 //
3632 // * In order to maintain SATB invariants, an object must not be
3633 // reclaimed if it was allocated before the start of marking and
3634 // has not had its references scanned. Such an object must have
3635 // its references (including type metadata) scanned to ensure no
3636 // live objects are missed by the marking process. Objects
3637 // allocated after the start of concurrent marking don't need to
3638 // be scanned.
3639 //
3640 // * An object must not be reclaimed if it is on the concurrent
3641 // mark stack. Objects allocated after the start of concurrent
3642 // marking are never pushed on the mark stack.
3643 //
3644 // Nominating only objects allocated after the start of concurrent
3645 // marking is sufficient to meet both constraints. This may miss
3646 // some objects that satisfy the constraints, but the marking data
3647 // structures don't support efficiently performing the needed
3648 // additional tests or scrubbing of the mark stack.
3649 //
3650 // However, we presently only nominate is_typeArray() objects.
3651 // A humongous object containing references induces remembered
3652 // set entries on other regions. In order to reclaim such an
3653 // object, those remembered sets would need to be cleaned up.
3654 //
3655 // We also treat is_typeArray() objects specially, allowing them
3656 // to be reclaimed even if allocated before the start of
3657 // concurrent mark. For this we rely on mark stack insertion to
3658 // exclude is_typeArray() objects, preventing reclaiming an object
3659 // that is in the mark stack. We also rely on the metadata for
3660 // such objects to be built-in and so ensured to be kept live.
3661 // Frequent allocation and drop of large binary blobs is an
3662 // important use case for eager reclaim, and this special handling
3663 // may reduce needed headroom.
3664
3665 return is_typeArray_region(region) && is_remset_small(region);
3666 }
3667
3668 public:
3669 RegisterHumongousWithInCSetFastTestClosure()
3670 : _total_humongous(0),
3671 _candidate_humongous(0),
3672 _dcq(&JavaThread::dirty_card_queue_set()) {
3673 }
3674
3675 virtual bool doHeapRegion(HeapRegion* r) {
3676 if (!r->is_starts_humongous()) {
3677 return false;
3678 }
3679 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3680
3681 bool is_candidate = humongous_region_is_candidate(g1h, r);
3682 uint rindex = r->hrm_index();
3683 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3684 if (is_candidate) {
3685 _candidate_humongous++;
3686 g1h->register_humongous_region_with_cset(rindex);
3687 // Is_candidate already filters out humongous object with large remembered sets.
3688 // If we have a humongous object with a few remembered sets, we simply flush these
3689 // remembered set entries into the DCQS. That will result in automatic
3690 // re-evaluation of their remembered set entries during the following evacuation
3691 // phase.
3692 if (!r->rem_set()->is_empty()) {
3693 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3694 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3695 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3696 HeapRegionRemSetIterator hrrs(r->rem_set());
3697 size_t card_index;
3698 while (hrrs.has_next(card_index)) {
3699 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3700 // The remembered set might contain references to already freed
3701 // regions. Filter out such entries to avoid failing card table
3702 // verification.
3703 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3704 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3705 *card_ptr = CardTableModRefBS::dirty_card_val();
3706 _dcq.enqueue(card_ptr);
3707 }
3708 }
3709 }
3710 r->rem_set()->clear_locked();
3711 }
3712 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3713 }
3714 _total_humongous++;
3715
3716 return false;
3717 }
3718
3719 size_t total_humongous() const { return _total_humongous; }
3720 size_t candidate_humongous() const { return _candidate_humongous; }
3721
3722 void flush_rem_set_entries() { _dcq.flush(); }
3723 };
3724
3725 void G1CollectedHeap::register_humongous_regions_with_cset() {
3726 if (!G1EagerReclaimHumongousObjects) {
3727 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3728 return;
3729 }
3730 double time = os::elapsed_counter();
3731
3732 // Collect reclaim candidate information and register candidates with cset.
3733 RegisterHumongousWithInCSetFastTestClosure cl;
3734 heap_region_iterate(&cl);
3735
3736 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3737 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3738 cl.total_humongous(),
3739 cl.candidate_humongous());
3740 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3741
3742 // Finally flush all remembered set entries to re-check into the global DCQS.
3743 cl.flush_rem_set_entries();
3744 }
3745
3746 void
3747 G1CollectedHeap::setup_surviving_young_words() {
3748 assert(_surviving_young_words == NULL, "pre-condition");
3749 uint array_length = g1_policy()->young_cset_region_length();
3750 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3751 if (_surviving_young_words == NULL) {
3752 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3753 "Not enough space for young surv words summary.");
3754 }
3755 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3756 #ifdef ASSERT
3757 for (uint i = 0; i < array_length; ++i) {
3758 assert( _surviving_young_words[i] == 0, "memset above" );
3759 }
3760 #endif // !ASSERT
3761 }
3762
3763 void
3764 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3765 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3766 uint array_length = g1_policy()->young_cset_region_length();
3767 for (uint i = 0; i < array_length; ++i) {
3768 _surviving_young_words[i] += surv_young_words[i];
3769 }
3770 }
3771
3772 void
3773 G1CollectedHeap::cleanup_surviving_young_words() {
3774 guarantee( _surviving_young_words != NULL, "pre-condition" );
3775 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3776 _surviving_young_words = NULL;
3777 }
3778
3779 #ifdef ASSERT
3780 class VerifyCSetClosure: public HeapRegionClosure {
3781 public:
3782 bool doHeapRegion(HeapRegion* hr) {
3783 // Here we check that the CSet region's RSet is ready for parallel
3784 // iteration. The fields that we'll verify are only manipulated
3785 // when the region is part of a CSet and is collected. Afterwards,
3786 // we reset these fields when we clear the region's RSet (when the
3787 // region is freed) so they are ready when the region is
3788 // re-allocated. The only exception to this is if there's an
3789 // evacuation failure and instead of freeing the region we leave
3790 // it in the heap. In that case, we reset these fields during
3791 // evacuation failure handling.
3792 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3793
3794 // Here's a good place to add any other checks we'd like to
3795 // perform on CSet regions.
3796 return false;
3797 }
3798 };
3799 #endif // ASSERT
3800
3801 uint G1CollectedHeap::num_task_queues() const {
3802 return _task_queues->size();
3803 }
3804
3805 #if TASKQUEUE_STATS
3806 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3807 st->print_raw_cr("GC Task Stats");
3808 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3809 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3810 }
3811
3812 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3813 print_taskqueue_stats_hdr(st);
3814
3815 TaskQueueStats totals;
3816 const uint n = num_task_queues();
3817 for (uint i = 0; i < n; ++i) {
3818 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3819 totals += task_queue(i)->stats;
3820 }
3821 st->print_raw("tot "); totals.print(st); st->cr();
3822
3823 DEBUG_ONLY(totals.verify());
3824 }
3825
3826 void G1CollectedHeap::reset_taskqueue_stats() {
3827 const uint n = num_task_queues();
3828 for (uint i = 0; i < n; ++i) {
3829 task_queue(i)->stats.reset();
3830 }
3831 }
3832 #endif // TASKQUEUE_STATS
3833
3834 void G1CollectedHeap::log_gc_header() {
3835 if (!G1Log::fine()) {
3836 return;
3837 }
3838
3839 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3840
3841 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3842 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3843 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3844
3845 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3846 }
3847
3848 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3849 if (!G1Log::fine()) {
3850 return;
3851 }
3852
3853 if (G1Log::finer()) {
3854 if (evacuation_failed()) {
3855 gclog_or_tty->print(" (to-space exhausted)");
3856 }
3857 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3858 g1_policy()->phase_times()->note_gc_end();
3859 g1_policy()->phase_times()->print(pause_time_sec);
3860 g1_policy()->print_detailed_heap_transition();
3861 } else {
3862 if (evacuation_failed()) {
3863 gclog_or_tty->print("--");
3864 }
3865 g1_policy()->print_heap_transition();
3866 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3867 }
3868 gclog_or_tty->flush();
3869 }
3870
3871 void G1CollectedHeap::wait_for_root_region_scanning() {
3872 double scan_wait_start = os::elapsedTime();
3873 // We have to wait until the CM threads finish scanning the
3874 // root regions as it's the only way to ensure that all the
3875 // objects on them have been correctly scanned before we start
3876 // moving them during the GC.
3877 bool waited = _cm->root_regions()->wait_until_scan_finished();
3878 double wait_time_ms = 0.0;
3879 if (waited) {
3880 double scan_wait_end = os::elapsedTime();
3881 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3882 }
3883 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3884 }
3885
3886 bool
3887 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3888 assert_at_safepoint(true /* should_be_vm_thread */);
3889 guarantee(!is_gc_active(), "collection is not reentrant");
3890
3891 if (GC_locker::check_active_before_gc()) {
3892 return false;
3893 }
3894
3895 _gc_timer_stw->register_gc_start();
3896
3897 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3898
3899 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3900 ResourceMark rm;
3901
3902 wait_for_root_region_scanning();
3903
3904 G1Log::update_level();
3905 print_heap_before_gc();
3906 trace_heap_before_gc(_gc_tracer_stw);
3907
3908 verify_region_sets_optional();
3909 verify_dirty_young_regions();
3910
3911 // This call will decide whether this pause is an initial-mark
3912 // pause. If it is, during_initial_mark_pause() will return true
3913 // for the duration of this pause.
3914 g1_policy()->decide_on_conc_mark_initiation();
3915
3916 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3917 assert(!collector_state()->during_initial_mark_pause() ||
3918 collector_state()->gcs_are_young(), "sanity");
3919
3920 // We also do not allow mixed GCs during marking.
3921 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3922
3923 // Record whether this pause is an initial mark. When the current
3924 // thread has completed its logging output and it's safe to signal
3925 // the CM thread, the flag's value in the policy has been reset.
3926 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3927
3928 // Inner scope for scope based logging, timers, and stats collection
3929 {
3930 EvacuationInfo evacuation_info;
3931
3932 if (collector_state()->during_initial_mark_pause()) {
3933 // We are about to start a marking cycle, so we increment the
3934 // full collection counter.
3935 increment_old_marking_cycles_started();
3936 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3937 }
3938
3939 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3940
3941 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3942
3943 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3944 workers()->active_workers(),
3945 Threads::number_of_non_daemon_threads());
3946 workers()->set_active_workers(active_workers);
3947
3948 double pause_start_sec = os::elapsedTime();
3949 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
3950 log_gc_header();
3951
3952 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3953 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3954
3955 // If the secondary_free_list is not empty, append it to the
3956 // free_list. No need to wait for the cleanup operation to finish;
3957 // the region allocation code will check the secondary_free_list
3958 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3959 // set, skip this step so that the region allocation code has to
3960 // get entries from the secondary_free_list.
3961 if (!G1StressConcRegionFreeing) {
3962 append_secondary_free_list_if_not_empty_with_lock();
3963 }
3964
3965 assert(check_young_list_well_formed(), "young list should be well formed");
3966
3967 // Don't dynamically change the number of GC threads this early. A value of
3968 // 0 is used to indicate serial work. When parallel work is done,
3969 // it will be set.
3970
3971 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3972 IsGCActiveMark x;
3973
3974 gc_prologue(false);
3975 increment_total_collections(false /* full gc */);
3976 increment_gc_time_stamp();
3977
3978 verify_before_gc();
3979
3980 check_bitmaps("GC Start");
3981
3982 COMPILER2_PRESENT(DerivedPointerTable::clear());
3983
3984 // Please see comment in g1CollectedHeap.hpp and
3985 // G1CollectedHeap::ref_processing_init() to see how
3986 // reference processing currently works in G1.
3987
3988 // Enable discovery in the STW reference processor
3989 ref_processor_stw()->enable_discovery();
3990
3991 {
3992 // We want to temporarily turn off discovery by the
3993 // CM ref processor, if necessary, and turn it back on
3994 // on again later if we do. Using a scoped
3995 // NoRefDiscovery object will do this.
3996 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3997
3998 // Forget the current alloc region (we might even choose it to be part
3999 // of the collection set!).
4000 _allocator->release_mutator_alloc_region();
4001
4002 // We should call this after we retire the mutator alloc
4003 // region(s) so that all the ALLOC / RETIRE events are generated
4004 // before the start GC event.
4005 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4006
4007 // This timing is only used by the ergonomics to handle our pause target.
4008 // It is unclear why this should not include the full pause. We will
4009 // investigate this in CR 7178365.
4010 //
4011 // Preserving the old comment here if that helps the investigation:
4012 //
4013 // The elapsed time induced by the start time below deliberately elides
4014 // the possible verification above.
4015 double sample_start_time_sec = os::elapsedTime();
4016
4017 #if YOUNG_LIST_VERBOSE
4018 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4019 _young_list->print();
4020 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4021 #endif // YOUNG_LIST_VERBOSE
4022
4023 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4024
4025 #if YOUNG_LIST_VERBOSE
4026 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4027 _young_list->print();
4028 #endif // YOUNG_LIST_VERBOSE
4029
4030 if (collector_state()->during_initial_mark_pause()) {
4031 concurrent_mark()->checkpointRootsInitialPre();
4032 }
4033
4034 #if YOUNG_LIST_VERBOSE
4035 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4036 _young_list->print();
4037 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4038 #endif // YOUNG_LIST_VERBOSE
4039
4040 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4041
4042 register_humongous_regions_with_cset();
4043
4044 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4045
4046 _cm->note_start_of_gc();
4047 // We call this after finalize_cset() to
4048 // ensure that the CSet has been finalized.
4049 _cm->verify_no_cset_oops();
4050
4051 if (_hr_printer.is_active()) {
4052 HeapRegion* hr = g1_policy()->collection_set();
4053 while (hr != NULL) {
4054 _hr_printer.cset(hr);
4055 hr = hr->next_in_collection_set();
4056 }
4057 }
4058
4059 #ifdef ASSERT
4060 VerifyCSetClosure cl;
4061 collection_set_iterate(&cl);
4062 #endif // ASSERT
4063
4064 setup_surviving_young_words();
4065
4066 // Initialize the GC alloc regions.
4067 _allocator->init_gc_alloc_regions(evacuation_info);
4068
4069 // Actually do the work...
4070 evacuate_collection_set(evacuation_info);
4071
4072 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4073
4074 eagerly_reclaim_humongous_regions();
4075
4076 g1_policy()->clear_collection_set();
4077
4078 cleanup_surviving_young_words();
4079
4080 // Start a new incremental collection set for the next pause.
4081 g1_policy()->start_incremental_cset_building();
4082
4083 clear_cset_fast_test();
4084
4085 _young_list->reset_sampled_info();
4086
4087 // Don't check the whole heap at this point as the
4088 // GC alloc regions from this pause have been tagged
4089 // as survivors and moved on to the survivor list.
4090 // Survivor regions will fail the !is_young() check.
4091 assert(check_young_list_empty(false /* check_heap */),
4092 "young list should be empty");
4093
4094 #if YOUNG_LIST_VERBOSE
4095 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4096 _young_list->print();
4097 #endif // YOUNG_LIST_VERBOSE
4098
4099 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4100 _young_list->first_survivor_region(),
4101 _young_list->last_survivor_region());
4102
4103 _young_list->reset_auxilary_lists();
4104
4105 if (evacuation_failed()) {
4106 set_used(recalculate_used());
4107 if (_archive_allocator != NULL) {
4108 _archive_allocator->clear_used();
4109 }
4110 for (uint i = 0; i < ParallelGCThreads; i++) {
4111 if (_evacuation_failed_info_array[i].has_failed()) {
4112 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4113 }
4114 }
4115 } else {
4116 // The "used" of the the collection set have already been subtracted
4117 // when they were freed. Add in the bytes evacuated.
4118 increase_used(g1_policy()->bytes_copied_during_gc());
4119 }
4120
4121 if (collector_state()->during_initial_mark_pause()) {
4122 // We have to do this before we notify the CM threads that
4123 // they can start working to make sure that all the
4124 // appropriate initialization is done on the CM object.
4125 concurrent_mark()->checkpointRootsInitialPost();
4126 collector_state()->set_mark_in_progress(true);
4127 // Note that we don't actually trigger the CM thread at
4128 // this point. We do that later when we're sure that
4129 // the current thread has completed its logging output.
4130 }
4131
4132 allocate_dummy_regions();
4133
4134 #if YOUNG_LIST_VERBOSE
4135 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4136 _young_list->print();
4137 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4138 #endif // YOUNG_LIST_VERBOSE
4139
4140 _allocator->init_mutator_alloc_region();
4141
4142 {
4143 size_t expand_bytes = g1_policy()->expansion_amount();
4144 if (expand_bytes > 0) {
4145 size_t bytes_before = capacity();
4146 // No need for an ergo verbose message here,
4147 // expansion_amount() does this when it returns a value > 0.
4148 if (!expand(expand_bytes)) {
4149 // We failed to expand the heap. Cannot do anything about it.
4150 }
4151 }
4152 }
4153
4154 // We redo the verification but now wrt to the new CSet which
4155 // has just got initialized after the previous CSet was freed.
4156 _cm->verify_no_cset_oops();
4157 _cm->note_end_of_gc();
4158
4159 // This timing is only used by the ergonomics to handle our pause target.
4160 // It is unclear why this should not include the full pause. We will
4161 // investigate this in CR 7178365.
4162 double sample_end_time_sec = os::elapsedTime();
4163 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4164 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4165
4166 MemoryService::track_memory_usage();
4167
4168 // In prepare_for_verify() below we'll need to scan the deferred
4169 // update buffers to bring the RSets up-to-date if
4170 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4171 // the update buffers we'll probably need to scan cards on the
4172 // regions we just allocated to (i.e., the GC alloc
4173 // regions). However, during the last GC we called
4174 // set_saved_mark() on all the GC alloc regions, so card
4175 // scanning might skip the [saved_mark_word()...top()] area of
4176 // those regions (i.e., the area we allocated objects into
4177 // during the last GC). But it shouldn't. Given that
4178 // saved_mark_word() is conditional on whether the GC time stamp
4179 // on the region is current or not, by incrementing the GC time
4180 // stamp here we invalidate all the GC time stamps on all the
4181 // regions and saved_mark_word() will simply return top() for
4182 // all the regions. This is a nicer way of ensuring this rather
4183 // than iterating over the regions and fixing them. In fact, the
4184 // GC time stamp increment here also ensures that
4185 // saved_mark_word() will return top() between pauses, i.e.,
4186 // during concurrent refinement. So we don't need the
4187 // is_gc_active() check to decided which top to use when
4188 // scanning cards (see CR 7039627).
4189 increment_gc_time_stamp();
4190
4191 verify_after_gc();
4192 check_bitmaps("GC End");
4193
4194 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4195 ref_processor_stw()->verify_no_references_recorded();
4196
4197 // CM reference discovery will be re-enabled if necessary.
4198 }
4199
4200 // We should do this after we potentially expand the heap so
4201 // that all the COMMIT events are generated before the end GC
4202 // event, and after we retire the GC alloc regions so that all
4203 // RETIRE events are generated before the end GC event.
4204 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4205
4206 #ifdef TRACESPINNING
4207 ParallelTaskTerminator::print_termination_counts();
4208 #endif
4209
4210 gc_epilogue(false);
4211 }
4212
4213 // Print the remainder of the GC log output.
4214 log_gc_footer(os::elapsedTime() - pause_start_sec);
4215
4216 // It is not yet to safe to tell the concurrent mark to
4217 // start as we have some optional output below. We don't want the
4218 // output from the concurrent mark thread interfering with this
4219 // logging output either.
4220
4221 _hrm.verify_optional();
4222 verify_region_sets_optional();
4223
4224 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4225 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4226
4227 print_heap_after_gc();
4228 trace_heap_after_gc(_gc_tracer_stw);
4229
4230 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4231 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4232 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4233 // before any GC notifications are raised.
4234 g1mm()->update_sizes();
4235
4236 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4237 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4238 _gc_timer_stw->register_gc_end();
4239 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4240 }
4241 // It should now be safe to tell the concurrent mark thread to start
4242 // without its logging output interfering with the logging output
4243 // that came from the pause.
4244
4245 if (should_start_conc_mark) {
4246 // CAUTION: after the doConcurrentMark() call below,
4247 // the concurrent marking thread(s) could be running
4248 // concurrently with us. Make sure that anything after
4249 // this point does not assume that we are the only GC thread
4250 // running. Note: of course, the actual marking work will
4251 // not start until the safepoint itself is released in
4252 // SuspendibleThreadSet::desynchronize().
4253 doConcurrentMark();
4254 }
4255
4256 return true;
4257 }
4258
4259 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4260 _drain_in_progress = false;
4261 set_evac_failure_closure(cl);
4262 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4263 }
4264
4265 void G1CollectedHeap::finalize_for_evac_failure() {
4266 assert(_evac_failure_scan_stack != NULL &&
4267 _evac_failure_scan_stack->length() == 0,
4268 "Postcondition");
4269 assert(!_drain_in_progress, "Postcondition");
4270 delete _evac_failure_scan_stack;
4271 _evac_failure_scan_stack = NULL;
4272 }
4273
4274 void G1CollectedHeap::remove_self_forwarding_pointers() {
4275 double remove_self_forwards_start = os::elapsedTime();
4276
4277 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4278 workers()->run_task(&rsfp_task);
4279
4280 // Now restore saved marks, if any.
4281 assert(_objs_with_preserved_marks.size() ==
4282 _preserved_marks_of_objs.size(), "Both or none.");
4283 while (!_objs_with_preserved_marks.is_empty()) {
4284 oop obj = _objs_with_preserved_marks.pop();
4285 markOop m = _preserved_marks_of_objs.pop();
4286 obj->set_mark(m);
4287 }
4288 _objs_with_preserved_marks.clear(true);
4289 _preserved_marks_of_objs.clear(true);
4290
4291 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4292 }
4293
4294 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4295 _evac_failure_scan_stack->push(obj);
4296 }
4297
4298 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4299 assert(_evac_failure_scan_stack != NULL, "precondition");
4300
4301 while (_evac_failure_scan_stack->length() > 0) {
4302 oop obj = _evac_failure_scan_stack->pop();
4303 _evac_failure_closure->set_region(heap_region_containing(obj));
4304 obj->oop_iterate_backwards(_evac_failure_closure);
4305 }
4306 }
4307
4308 oop
4309 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4310 oop old) {
4311 assert(obj_in_cs(old),
4312 err_msg("obj: " PTR_FORMAT " should still be in the CSet",
4313 p2i(old)));
4314 markOop m = old->mark();
4315 oop forward_ptr = old->forward_to_atomic(old);
4316 if (forward_ptr == NULL) {
4317 // Forward-to-self succeeded.
4318 assert(_par_scan_state != NULL, "par scan state");
4319 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4320 uint queue_num = _par_scan_state->queue_num();
4321
4322 _evacuation_failed = true;
4323 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4324 if (_evac_failure_closure != cl) {
4325 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4326 assert(!_drain_in_progress,
4327 "Should only be true while someone holds the lock.");
4328 // Set the global evac-failure closure to the current thread's.
4329 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4330 set_evac_failure_closure(cl);
4331 // Now do the common part.
4332 handle_evacuation_failure_common(old, m);
4333 // Reset to NULL.
4334 set_evac_failure_closure(NULL);
4335 } else {
4336 // The lock is already held, and this is recursive.
4337 assert(_drain_in_progress, "This should only be the recursive case.");
4338 handle_evacuation_failure_common(old, m);
4339 }
4340 return old;
4341 } else {
4342 // Forward-to-self failed. Either someone else managed to allocate
4343 // space for this object (old != forward_ptr) or they beat us in
4344 // self-forwarding it (old == forward_ptr).
4345 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4346 err_msg("obj: " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
4347 "should not be in the CSet",
4348 p2i(old), p2i(forward_ptr)));
4349 return forward_ptr;
4350 }
4351 }
4352
4353 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4354 preserve_mark_if_necessary(old, m);
4355
4356 HeapRegion* r = heap_region_containing(old);
4357 if (!r->evacuation_failed()) {
4358 r->set_evacuation_failed(true);
4359 _hr_printer.evac_failure(r);
4360 }
4361
4362 push_on_evac_failure_scan_stack(old);
4363
4364 if (!_drain_in_progress) {
4365 // prevent recursion in copy_to_survivor_space()
4366 _drain_in_progress = true;
4367 drain_evac_failure_scan_stack();
4368 _drain_in_progress = false;
4369 }
4370 }
4371
4372 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4373 assert(evacuation_failed(), "Oversaving!");
4374 // We want to call the "for_promotion_failure" version only in the
4375 // case of a promotion failure.
4376 if (m->must_be_preserved_for_promotion_failure(obj)) {
4377 _objs_with_preserved_marks.push(obj);
4378 _preserved_marks_of_objs.push(m);
4379 }
4380 }
4381
4382 void G1ParCopyHelper::mark_object(oop obj) {
4383 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4384
4385 // We know that the object is not moving so it's safe to read its size.
4386 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4387 }
4388
4389 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4390 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4391 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4392 assert(from_obj != to_obj, "should not be self-forwarded");
4393
4394 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4395 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4396
4397 // The object might be in the process of being copied by another
4398 // worker so we cannot trust that its to-space image is
4399 // well-formed. So we have to read its size from its from-space
4400 // image which we know should not be changing.
4401 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4402 }
4403
4404 template <class T>
4405 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4406 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4407 _scanned_klass->record_modified_oops();
4408 }
4409 }
4410
4411 template <G1Barrier barrier, G1Mark do_mark_object>
4412 template <class T>
4413 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4414 T heap_oop = oopDesc::load_heap_oop(p);
4415
4416 if (oopDesc::is_null(heap_oop)) {
4417 return;
4418 }
4419
4420 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4421
4422 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4423
4424 const InCSetState state = _g1->in_cset_state(obj);
4425 if (state.is_in_cset()) {
4426 oop forwardee;
4427 markOop m = obj->mark();
4428 if (m->is_marked()) {
4429 forwardee = (oop) m->decode_pointer();
4430 } else {
4431 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4432 }
4433 assert(forwardee != NULL, "forwardee should not be NULL");
4434 oopDesc::encode_store_heap_oop(p, forwardee);
4435 if (do_mark_object != G1MarkNone && forwardee != obj) {
4436 // If the object is self-forwarded we don't need to explicitly
4437 // mark it, the evacuation failure protocol will do so.
4438 mark_forwarded_object(obj, forwardee);
4439 }
4440
4441 if (barrier == G1BarrierKlass) {
4442 do_klass_barrier(p, forwardee);
4443 }
4444 } else {
4445 if (state.is_humongous()) {
4446 _g1->set_humongous_is_live(obj);
4447 }
4448 // The object is not in collection set. If we're a root scanning
4449 // closure during an initial mark pause then attempt to mark the object.
4450 if (do_mark_object == G1MarkFromRoot) {
4451 mark_object(obj);
4452 }
4453 }
4454
4455 if (barrier == G1BarrierEvac) {
4456 _par_scan_state->update_rs(_from, p, _worker_id);
4457 }
4458 }
4459
4460 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4461 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4462
4463 class G1ParEvacuateFollowersClosure : public VoidClosure {
4464 protected:
4465 G1CollectedHeap* _g1h;
4466 G1ParScanThreadState* _par_scan_state;
4467 RefToScanQueueSet* _queues;
4468 ParallelTaskTerminator* _terminator;
4469
4470 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4471 RefToScanQueueSet* queues() { return _queues; }
4472 ParallelTaskTerminator* terminator() { return _terminator; }
4473
4474 public:
4475 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4476 G1ParScanThreadState* par_scan_state,
4477 RefToScanQueueSet* queues,
4478 ParallelTaskTerminator* terminator)
4479 : _g1h(g1h), _par_scan_state(par_scan_state),
4480 _queues(queues), _terminator(terminator) {}
4481
4482 void do_void();
4483
4484 private:
4485 inline bool offer_termination();
4486 };
4487
4488 bool G1ParEvacuateFollowersClosure::offer_termination() {
4489 G1ParScanThreadState* const pss = par_scan_state();
4490 pss->start_term_time();
4491 const bool res = terminator()->offer_termination();
4492 pss->end_term_time();
4493 return res;
4494 }
4495
4496 void G1ParEvacuateFollowersClosure::do_void() {
4497 G1ParScanThreadState* const pss = par_scan_state();
4498 pss->trim_queue();
4499 do {
4500 pss->steal_and_trim_queue(queues());
4501 } while (!offer_termination());
4502 }
4503
4504 class G1KlassScanClosure : public KlassClosure {
4505 G1ParCopyHelper* _closure;
4506 bool _process_only_dirty;
4507 int _count;
4508 public:
4509 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4510 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4511 void do_klass(Klass* klass) {
4512 // If the klass has not been dirtied we know that there's
4513 // no references into the young gen and we can skip it.
4514 if (!_process_only_dirty || klass->has_modified_oops()) {
4515 // Clean the klass since we're going to scavenge all the metadata.
4516 klass->clear_modified_oops();
4517
4518 // Tell the closure that this klass is the Klass to scavenge
4519 // and is the one to dirty if oops are left pointing into the young gen.
4520 _closure->set_scanned_klass(klass);
4521
4522 klass->oops_do(_closure);
4523
4524 _closure->set_scanned_klass(NULL);
4525 }
4526 _count++;
4527 }
4528 };
4529
4530 class G1ParTask : public AbstractGangTask {
4531 protected:
4532 G1CollectedHeap* _g1h;
4533 RefToScanQueueSet *_queues;
4534 G1RootProcessor* _root_processor;
4535 ParallelTaskTerminator _terminator;
4536 uint _n_workers;
4537
4538 Mutex _stats_lock;
4539 Mutex* stats_lock() { return &_stats_lock; }
4540
4541 public:
4542 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4543 : AbstractGangTask("G1 collection"),
4544 _g1h(g1h),
4545 _queues(task_queues),
4546 _root_processor(root_processor),
4547 _terminator(n_workers, _queues),
4548 _n_workers(n_workers),
4549 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4550 {}
4551
4552 RefToScanQueueSet* queues() { return _queues; }
4553
4554 RefToScanQueue *work_queue(int i) {
4555 return queues()->queue(i);
4556 }
4557
4558 ParallelTaskTerminator* terminator() { return &_terminator; }
4559
4560 // Helps out with CLD processing.
4561 //
4562 // During InitialMark we need to:
4563 // 1) Scavenge all CLDs for the young GC.
4564 // 2) Mark all objects directly reachable from strong CLDs.
4565 template <G1Mark do_mark_object>
4566 class G1CLDClosure : public CLDClosure {
4567 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4568 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4569 G1KlassScanClosure _klass_in_cld_closure;
4570 bool _claim;
4571
4572 public:
4573 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4574 bool only_young, bool claim)
4575 : _oop_closure(oop_closure),
4576 _oop_in_klass_closure(oop_closure->g1(),
4577 oop_closure->pss(),
4578 oop_closure->rp()),
4579 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4580 _claim(claim) {
4581
4582 }
4583
4584 void do_cld(ClassLoaderData* cld) {
4585 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4586 }
4587 };
4588
4589 void work(uint worker_id) {
4590 if (worker_id >= _n_workers) return; // no work needed this round
4591
4592 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4593
4594 {
4595 ResourceMark rm;
4596 HandleMark hm;
4597
4598 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4599
4600 G1ParScanThreadState pss(_g1h, worker_id, rp);
4601 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4602
4603 pss.set_evac_failure_closure(&evac_failure_cl);
4604
4605 bool only_young = _g1h->collector_state()->gcs_are_young();
4606
4607 // Non-IM young GC.
4608 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4609 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4610 only_young, // Only process dirty klasses.
4611 false); // No need to claim CLDs.
4612 // IM young GC.
4613 // Strong roots closures.
4614 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4615 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4616 false, // Process all klasses.
4617 true); // Need to claim CLDs.
4618 // Weak roots closures.
4619 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4620 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4621 false, // Process all klasses.
4622 true); // Need to claim CLDs.
4623
4624 OopClosure* strong_root_cl;
4625 OopClosure* weak_root_cl;
4626 CLDClosure* strong_cld_cl;
4627 CLDClosure* weak_cld_cl;
4628
4629 bool trace_metadata = false;
4630
4631 if (_g1h->collector_state()->during_initial_mark_pause()) {
4632 // We also need to mark copied objects.
4633 strong_root_cl = &scan_mark_root_cl;
4634 strong_cld_cl = &scan_mark_cld_cl;
4635 if (ClassUnloadingWithConcurrentMark) {
4636 weak_root_cl = &scan_mark_weak_root_cl;
4637 weak_cld_cl = &scan_mark_weak_cld_cl;
4638 trace_metadata = true;
4639 } else {
4640 weak_root_cl = &scan_mark_root_cl;
4641 weak_cld_cl = &scan_mark_cld_cl;
4642 }
4643 } else {
4644 strong_root_cl = &scan_only_root_cl;
4645 weak_root_cl = &scan_only_root_cl;
4646 strong_cld_cl = &scan_only_cld_cl;
4647 weak_cld_cl = &scan_only_cld_cl;
4648 }
4649
4650 pss.start_strong_roots();
4651
4652 _root_processor->evacuate_roots(strong_root_cl,
4653 weak_root_cl,
4654 strong_cld_cl,
4655 weak_cld_cl,
4656 trace_metadata,
4657 worker_id);
4658
4659 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4660 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4661 weak_root_cl,
4662 worker_id);
4663 pss.end_strong_roots();
4664
4665 {
4666 double start = os::elapsedTime();
4667 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4668 evac.do_void();
4669 double elapsed_sec = os::elapsedTime() - start;
4670 double term_sec = pss.term_time();
4671 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4672 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4673 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4674 }
4675 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4676 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4677
4678 if (PrintTerminationStats) {
4679 MutexLocker x(stats_lock());
4680 pss.print_termination_stats(worker_id);
4681 }
4682
4683 assert(pss.queue_is_empty(), "should be empty");
4684
4685 // Close the inner scope so that the ResourceMark and HandleMark
4686 // destructors are executed here and are included as part of the
4687 // "GC Worker Time".
4688 }
4689 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4690 }
4691 };
4692
4693 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4694 private:
4695 BoolObjectClosure* _is_alive;
4696 int _initial_string_table_size;
4697 int _initial_symbol_table_size;
4698
4699 bool _process_strings;
4700 int _strings_processed;
4701 int _strings_removed;
4702
4703 bool _process_symbols;
4704 int _symbols_processed;
4705 int _symbols_removed;
4706
4707 public:
4708 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4709 AbstractGangTask("String/Symbol Unlinking"),
4710 _is_alive(is_alive),
4711 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4712 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4713
4714 _initial_string_table_size = StringTable::the_table()->table_size();
4715 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4716 if (process_strings) {
4717 StringTable::clear_parallel_claimed_index();
4718 }
4719 if (process_symbols) {
4720 SymbolTable::clear_parallel_claimed_index();
4721 }
4722 }
4723
4724 ~G1StringSymbolTableUnlinkTask() {
4725 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4726 err_msg("claim value %d after unlink less than initial string table size %d",
4727 StringTable::parallel_claimed_index(), _initial_string_table_size));
4728 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4729 err_msg("claim value %d after unlink less than initial symbol table size %d",
4730 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4731
4732 if (G1TraceStringSymbolTableScrubbing) {
4733 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4734 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4735 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4736 strings_processed(), strings_removed(),
4737 symbols_processed(), symbols_removed());
4738 }
4739 }
4740
4741 void work(uint worker_id) {
4742 int strings_processed = 0;
4743 int strings_removed = 0;
4744 int symbols_processed = 0;
4745 int symbols_removed = 0;
4746 if (_process_strings) {
4747 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4748 Atomic::add(strings_processed, &_strings_processed);
4749 Atomic::add(strings_removed, &_strings_removed);
4750 }
4751 if (_process_symbols) {
4752 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4753 Atomic::add(symbols_processed, &_symbols_processed);
4754 Atomic::add(symbols_removed, &_symbols_removed);
4755 }
4756 }
4757
4758 size_t strings_processed() const { return (size_t)_strings_processed; }
4759 size_t strings_removed() const { return (size_t)_strings_removed; }
4760
4761 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4762 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4763 };
4764
4765 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4766 private:
4767 static Monitor* _lock;
4768
4769 BoolObjectClosure* const _is_alive;
4770 const bool _unloading_occurred;
4771 const uint _num_workers;
4772
4773 // Variables used to claim nmethods.
4774 nmethod* _first_nmethod;
4775 volatile nmethod* _claimed_nmethod;
4776
4777 // The list of nmethods that need to be processed by the second pass.
4778 volatile nmethod* _postponed_list;
4779 volatile uint _num_entered_barrier;
4780
4781 public:
4782 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4783 _is_alive(is_alive),
4784 _unloading_occurred(unloading_occurred),
4785 _num_workers(num_workers),
4786 _first_nmethod(NULL),
4787 _claimed_nmethod(NULL),
4788 _postponed_list(NULL),
4789 _num_entered_barrier(0)
4790 {
4791 nmethod::increase_unloading_clock();
4792 // Get first alive nmethod
4793 NMethodIterator iter = NMethodIterator();
4794 if(iter.next_alive()) {
4795 _first_nmethod = iter.method();
4796 }
4797 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4798 }
4799
4800 ~G1CodeCacheUnloadingTask() {
4801 CodeCache::verify_clean_inline_caches();
4802
4803 CodeCache::set_needs_cache_clean(false);
4804 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4805
4806 CodeCache::verify_icholder_relocations();
4807 }
4808
4809 private:
4810 void add_to_postponed_list(nmethod* nm) {
4811 nmethod* old;
4812 do {
4813 old = (nmethod*)_postponed_list;
4814 nm->set_unloading_next(old);
4815 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4816 }
4817
4818 void clean_nmethod(nmethod* nm) {
4819 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4820
4821 if (postponed) {
4822 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4823 add_to_postponed_list(nm);
4824 }
4825
4826 // Mark that this thread has been cleaned/unloaded.
4827 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4828 nm->set_unloading_clock(nmethod::global_unloading_clock());
4829 }
4830
4831 void clean_nmethod_postponed(nmethod* nm) {
4832 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4833 }
4834
4835 static const int MaxClaimNmethods = 16;
4836
4837 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4838 nmethod* first;
4839 NMethodIterator last;
4840
4841 do {
4842 *num_claimed_nmethods = 0;
4843
4844 first = (nmethod*)_claimed_nmethod;
4845 last = NMethodIterator(first);
4846
4847 if (first != NULL) {
4848
4849 for (int i = 0; i < MaxClaimNmethods; i++) {
4850 if (!last.next_alive()) {
4851 break;
4852 }
4853 claimed_nmethods[i] = last.method();
4854 (*num_claimed_nmethods)++;
4855 }
4856 }
4857
4858 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4859 }
4860
4861 nmethod* claim_postponed_nmethod() {
4862 nmethod* claim;
4863 nmethod* next;
4864
4865 do {
4866 claim = (nmethod*)_postponed_list;
4867 if (claim == NULL) {
4868 return NULL;
4869 }
4870
4871 next = claim->unloading_next();
4872
4873 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4874
4875 return claim;
4876 }
4877
4878 public:
4879 // Mark that we're done with the first pass of nmethod cleaning.
4880 void barrier_mark(uint worker_id) {
4881 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4882 _num_entered_barrier++;
4883 if (_num_entered_barrier == _num_workers) {
4884 ml.notify_all();
4885 }
4886 }
4887
4888 // See if we have to wait for the other workers to
4889 // finish their first-pass nmethod cleaning work.
4890 void barrier_wait(uint worker_id) {
4891 if (_num_entered_barrier < _num_workers) {
4892 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4893 while (_num_entered_barrier < _num_workers) {
4894 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4895 }
4896 }
4897 }
4898
4899 // Cleaning and unloading of nmethods. Some work has to be postponed
4900 // to the second pass, when we know which nmethods survive.
4901 void work_first_pass(uint worker_id) {
4902 // The first nmethods is claimed by the first worker.
4903 if (worker_id == 0 && _first_nmethod != NULL) {
4904 clean_nmethod(_first_nmethod);
4905 _first_nmethod = NULL;
4906 }
4907
4908 int num_claimed_nmethods;
4909 nmethod* claimed_nmethods[MaxClaimNmethods];
4910
4911 while (true) {
4912 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4913
4914 if (num_claimed_nmethods == 0) {
4915 break;
4916 }
4917
4918 for (int i = 0; i < num_claimed_nmethods; i++) {
4919 clean_nmethod(claimed_nmethods[i]);
4920 }
4921 }
4922 }
4923
4924 void work_second_pass(uint worker_id) {
4925 nmethod* nm;
4926 // Take care of postponed nmethods.
4927 while ((nm = claim_postponed_nmethod()) != NULL) {
4928 clean_nmethod_postponed(nm);
4929 }
4930 }
4931 };
4932
4933 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4934
4935 class G1KlassCleaningTask : public StackObj {
4936 BoolObjectClosure* _is_alive;
4937 volatile jint _clean_klass_tree_claimed;
4938 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4939
4940 public:
4941 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4942 _is_alive(is_alive),
4943 _clean_klass_tree_claimed(0),
4944 _klass_iterator() {
4945 }
4946
4947 private:
4948 bool claim_clean_klass_tree_task() {
4949 if (_clean_klass_tree_claimed) {
4950 return false;
4951 }
4952
4953 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4954 }
4955
4956 InstanceKlass* claim_next_klass() {
4957 Klass* klass;
4958 do {
4959 klass =_klass_iterator.next_klass();
4960 } while (klass != NULL && !klass->oop_is_instance());
4961
4962 return (InstanceKlass*)klass;
4963 }
4964
4965 public:
4966
4967 void clean_klass(InstanceKlass* ik) {
4968 ik->clean_implementors_list(_is_alive);
4969 ik->clean_method_data(_is_alive);
4970
4971 // G1 specific cleanup work that has
4972 // been moved here to be done in parallel.
4973 ik->clean_dependent_nmethods();
4974 }
4975
4976 void work() {
4977 ResourceMark rm;
4978
4979 // One worker will clean the subklass/sibling klass tree.
4980 if (claim_clean_klass_tree_task()) {
4981 Klass::clean_subklass_tree(_is_alive);
4982 }
4983
4984 // All workers will help cleaning the classes,
4985 InstanceKlass* klass;
4986 while ((klass = claim_next_klass()) != NULL) {
4987 clean_klass(klass);
4988 }
4989 }
4990 };
4991
4992 // To minimize the remark pause times, the tasks below are done in parallel.
4993 class G1ParallelCleaningTask : public AbstractGangTask {
4994 private:
4995 G1StringSymbolTableUnlinkTask _string_symbol_task;
4996 G1CodeCacheUnloadingTask _code_cache_task;
4997 G1KlassCleaningTask _klass_cleaning_task;
4998
4999 public:
5000 // The constructor is run in the VMThread.
5001 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5002 AbstractGangTask("Parallel Cleaning"),
5003 _string_symbol_task(is_alive, process_strings, process_symbols),
5004 _code_cache_task(num_workers, is_alive, unloading_occurred),
5005 _klass_cleaning_task(is_alive) {
5006 }
5007
5008 // The parallel work done by all worker threads.
5009 void work(uint worker_id) {
5010 // Do first pass of code cache cleaning.
5011 _code_cache_task.work_first_pass(worker_id);
5012
5013 // Let the threads mark that the first pass is done.
5014 _code_cache_task.barrier_mark(worker_id);
5015
5016 // Clean the Strings and Symbols.
5017 _string_symbol_task.work(worker_id);
5018
5019 // Wait for all workers to finish the first code cache cleaning pass.
5020 _code_cache_task.barrier_wait(worker_id);
5021
5022 // Do the second code cache cleaning work, which realize on
5023 // the liveness information gathered during the first pass.
5024 _code_cache_task.work_second_pass(worker_id);
5025
5026 // Clean all klasses that were not unloaded.
5027 _klass_cleaning_task.work();
5028 }
5029 };
5030
5031
5032 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5033 bool process_strings,
5034 bool process_symbols,
5035 bool class_unloading_occurred) {
5036 uint n_workers = workers()->active_workers();
5037
5038 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5039 n_workers, class_unloading_occurred);
5040 workers()->run_task(&g1_unlink_task);
5041 }
5042
5043 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5044 bool process_strings, bool process_symbols) {
5045 {
5046 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5047 workers()->run_task(&g1_unlink_task);
5048 }
5049
5050 if (G1StringDedup::is_enabled()) {
5051 G1StringDedup::unlink(is_alive);
5052 }
5053 }
5054
5055 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5056 private:
5057 DirtyCardQueueSet* _queue;
5058 public:
5059 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5060
5061 virtual void work(uint worker_id) {
5062 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5063 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5064
5065 RedirtyLoggedCardTableEntryClosure cl;
5066 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5067
5068 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5069 }
5070 };
5071
5072 void G1CollectedHeap::redirty_logged_cards() {
5073 double redirty_logged_cards_start = os::elapsedTime();
5074
5075 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5076 dirty_card_queue_set().reset_for_par_iteration();
5077 workers()->run_task(&redirty_task);
5078
5079 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5080 dcq.merge_bufferlists(&dirty_card_queue_set());
5081 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5082
5083 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5084 }
5085
5086 // Weak Reference Processing support
5087
5088 // An always "is_alive" closure that is used to preserve referents.
5089 // If the object is non-null then it's alive. Used in the preservation
5090 // of referent objects that are pointed to by reference objects
5091 // discovered by the CM ref processor.
5092 class G1AlwaysAliveClosure: public BoolObjectClosure {
5093 G1CollectedHeap* _g1;
5094 public:
5095 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5096 bool do_object_b(oop p) {
5097 if (p != NULL) {
5098 return true;
5099 }
5100 return false;
5101 }
5102 };
5103
5104 bool G1STWIsAliveClosure::do_object_b(oop p) {
5105 // An object is reachable if it is outside the collection set,
5106 // or is inside and copied.
5107 return !_g1->obj_in_cs(p) || p->is_forwarded();
5108 }
5109
5110 // Non Copying Keep Alive closure
5111 class G1KeepAliveClosure: public OopClosure {
5112 G1CollectedHeap* _g1;
5113 public:
5114 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5115 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5116 void do_oop(oop* p) {
5117 oop obj = *p;
5118 assert(obj != NULL, "the caller should have filtered out NULL values");
5119
5120 const InCSetState cset_state = _g1->in_cset_state(obj);
5121 if (!cset_state.is_in_cset_or_humongous()) {
5122 return;
5123 }
5124 if (cset_state.is_in_cset()) {
5125 assert( obj->is_forwarded(), "invariant" );
5126 *p = obj->forwardee();
5127 } else {
5128 assert(!obj->is_forwarded(), "invariant" );
5129 assert(cset_state.is_humongous(),
5130 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5131 _g1->set_humongous_is_live(obj);
5132 }
5133 }
5134 };
5135
5136 // Copying Keep Alive closure - can be called from both
5137 // serial and parallel code as long as different worker
5138 // threads utilize different G1ParScanThreadState instances
5139 // and different queues.
5140
5141 class G1CopyingKeepAliveClosure: public OopClosure {
5142 G1CollectedHeap* _g1h;
5143 OopClosure* _copy_non_heap_obj_cl;
5144 G1ParScanThreadState* _par_scan_state;
5145
5146 public:
5147 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5148 OopClosure* non_heap_obj_cl,
5149 G1ParScanThreadState* pss):
5150 _g1h(g1h),
5151 _copy_non_heap_obj_cl(non_heap_obj_cl),
5152 _par_scan_state(pss)
5153 {}
5154
5155 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5156 virtual void do_oop( oop* p) { do_oop_work(p); }
5157
5158 template <class T> void do_oop_work(T* p) {
5159 oop obj = oopDesc::load_decode_heap_oop(p);
5160
5161 if (_g1h->is_in_cset_or_humongous(obj)) {
5162 // If the referent object has been forwarded (either copied
5163 // to a new location or to itself in the event of an
5164 // evacuation failure) then we need to update the reference
5165 // field and, if both reference and referent are in the G1
5166 // heap, update the RSet for the referent.
5167 //
5168 // If the referent has not been forwarded then we have to keep
5169 // it alive by policy. Therefore we have copy the referent.
5170 //
5171 // If the reference field is in the G1 heap then we can push
5172 // on the PSS queue. When the queue is drained (after each
5173 // phase of reference processing) the object and it's followers
5174 // will be copied, the reference field set to point to the
5175 // new location, and the RSet updated. Otherwise we need to
5176 // use the the non-heap or metadata closures directly to copy
5177 // the referent object and update the pointer, while avoiding
5178 // updating the RSet.
5179
5180 if (_g1h->is_in_g1_reserved(p)) {
5181 _par_scan_state->push_on_queue(p);
5182 } else {
5183 assert(!Metaspace::contains((const void*)p),
5184 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5185 _copy_non_heap_obj_cl->do_oop(p);
5186 }
5187 }
5188 }
5189 };
5190
5191 // Serial drain queue closure. Called as the 'complete_gc'
5192 // closure for each discovered list in some of the
5193 // reference processing phases.
5194
5195 class G1STWDrainQueueClosure: public VoidClosure {
5196 protected:
5197 G1CollectedHeap* _g1h;
5198 G1ParScanThreadState* _par_scan_state;
5199
5200 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5201
5202 public:
5203 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5204 _g1h(g1h),
5205 _par_scan_state(pss)
5206 { }
5207
5208 void do_void() {
5209 G1ParScanThreadState* const pss = par_scan_state();
5210 pss->trim_queue();
5211 }
5212 };
5213
5214 // Parallel Reference Processing closures
5215
5216 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5217 // processing during G1 evacuation pauses.
5218
5219 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5220 private:
5221 G1CollectedHeap* _g1h;
5222 RefToScanQueueSet* _queues;
5223 FlexibleWorkGang* _workers;
5224 uint _active_workers;
5225
5226 public:
5227 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5228 FlexibleWorkGang* workers,
5229 RefToScanQueueSet *task_queues,
5230 uint n_workers) :
5231 _g1h(g1h),
5232 _queues(task_queues),
5233 _workers(workers),
5234 _active_workers(n_workers)
5235 {
5236 assert(n_workers > 0, "shouldn't call this otherwise");
5237 }
5238
5239 // Executes the given task using concurrent marking worker threads.
5240 virtual void execute(ProcessTask& task);
5241 virtual void execute(EnqueueTask& task);
5242 };
5243
5244 // Gang task for possibly parallel reference processing
5245
5246 class G1STWRefProcTaskProxy: public AbstractGangTask {
5247 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5248 ProcessTask& _proc_task;
5249 G1CollectedHeap* _g1h;
5250 RefToScanQueueSet *_task_queues;
5251 ParallelTaskTerminator* _terminator;
5252
5253 public:
5254 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5255 G1CollectedHeap* g1h,
5256 RefToScanQueueSet *task_queues,
5257 ParallelTaskTerminator* terminator) :
5258 AbstractGangTask("Process reference objects in parallel"),
5259 _proc_task(proc_task),
5260 _g1h(g1h),
5261 _task_queues(task_queues),
5262 _terminator(terminator)
5263 {}
5264
5265 virtual void work(uint worker_id) {
5266 // The reference processing task executed by a single worker.
5267 ResourceMark rm;
5268 HandleMark hm;
5269
5270 G1STWIsAliveClosure is_alive(_g1h);
5271
5272 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5273 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5274
5275 pss.set_evac_failure_closure(&evac_failure_cl);
5276
5277 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5278
5279 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5280
5281 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5282
5283 if (_g1h->collector_state()->during_initial_mark_pause()) {
5284 // We also need to mark copied objects.
5285 copy_non_heap_cl = ©_mark_non_heap_cl;
5286 }
5287
5288 // Keep alive closure.
5289 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5290
5291 // Complete GC closure
5292 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5293
5294 // Call the reference processing task's work routine.
5295 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5296
5297 // Note we cannot assert that the refs array is empty here as not all
5298 // of the processing tasks (specifically phase2 - pp2_work) execute
5299 // the complete_gc closure (which ordinarily would drain the queue) so
5300 // the queue may not be empty.
5301 }
5302 };
5303
5304 // Driver routine for parallel reference processing.
5305 // Creates an instance of the ref processing gang
5306 // task and has the worker threads execute it.
5307 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5308 assert(_workers != NULL, "Need parallel worker threads.");
5309
5310 ParallelTaskTerminator terminator(_active_workers, _queues);
5311 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5312
5313 _workers->run_task(&proc_task_proxy);
5314 }
5315
5316 // Gang task for parallel reference enqueueing.
5317
5318 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5319 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5320 EnqueueTask& _enq_task;
5321
5322 public:
5323 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5324 AbstractGangTask("Enqueue reference objects in parallel"),
5325 _enq_task(enq_task)
5326 { }
5327
5328 virtual void work(uint worker_id) {
5329 _enq_task.work(worker_id);
5330 }
5331 };
5332
5333 // Driver routine for parallel reference enqueueing.
5334 // Creates an instance of the ref enqueueing gang
5335 // task and has the worker threads execute it.
5336
5337 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5338 assert(_workers != NULL, "Need parallel worker threads.");
5339
5340 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5341
5342 _workers->run_task(&enq_task_proxy);
5343 }
5344
5345 // End of weak reference support closures
5346
5347 // Abstract task used to preserve (i.e. copy) any referent objects
5348 // that are in the collection set and are pointed to by reference
5349 // objects discovered by the CM ref processor.
5350
5351 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5352 protected:
5353 G1CollectedHeap* _g1h;
5354 RefToScanQueueSet *_queues;
5355 ParallelTaskTerminator _terminator;
5356 uint _n_workers;
5357
5358 public:
5359 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5360 AbstractGangTask("ParPreserveCMReferents"),
5361 _g1h(g1h),
5362 _queues(task_queues),
5363 _terminator(workers, _queues),
5364 _n_workers(workers)
5365 { }
5366
5367 void work(uint worker_id) {
5368 ResourceMark rm;
5369 HandleMark hm;
5370
5371 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5372 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5373
5374 pss.set_evac_failure_closure(&evac_failure_cl);
5375
5376 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5377
5378 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5379
5380 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5381
5382 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5383
5384 if (_g1h->collector_state()->during_initial_mark_pause()) {
5385 // We also need to mark copied objects.
5386 copy_non_heap_cl = ©_mark_non_heap_cl;
5387 }
5388
5389 // Is alive closure
5390 G1AlwaysAliveClosure always_alive(_g1h);
5391
5392 // Copying keep alive closure. Applied to referent objects that need
5393 // to be copied.
5394 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5395
5396 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5397
5398 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5399 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5400
5401 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5402 // So this must be true - but assert just in case someone decides to
5403 // change the worker ids.
5404 assert(worker_id < limit, "sanity");
5405 assert(!rp->discovery_is_atomic(), "check this code");
5406
5407 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5408 for (uint idx = worker_id; idx < limit; idx += stride) {
5409 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5410
5411 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5412 while (iter.has_next()) {
5413 // Since discovery is not atomic for the CM ref processor, we
5414 // can see some null referent objects.
5415 iter.load_ptrs(DEBUG_ONLY(true));
5416 oop ref = iter.obj();
5417
5418 // This will filter nulls.
5419 if (iter.is_referent_alive()) {
5420 iter.make_referent_alive();
5421 }
5422 iter.move_to_next();
5423 }
5424 }
5425
5426 // Drain the queue - which may cause stealing
5427 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5428 drain_queue.do_void();
5429 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5430 assert(pss.queue_is_empty(), "should be");
5431 }
5432 };
5433
5434 // Weak Reference processing during an evacuation pause (part 1).
5435 void G1CollectedHeap::process_discovered_references() {
5436 double ref_proc_start = os::elapsedTime();
5437
5438 ReferenceProcessor* rp = _ref_processor_stw;
5439 assert(rp->discovery_enabled(), "should have been enabled");
5440
5441 // Any reference objects, in the collection set, that were 'discovered'
5442 // by the CM ref processor should have already been copied (either by
5443 // applying the external root copy closure to the discovered lists, or
5444 // by following an RSet entry).
5445 //
5446 // But some of the referents, that are in the collection set, that these
5447 // reference objects point to may not have been copied: the STW ref
5448 // processor would have seen that the reference object had already
5449 // been 'discovered' and would have skipped discovering the reference,
5450 // but would not have treated the reference object as a regular oop.
5451 // As a result the copy closure would not have been applied to the
5452 // referent object.
5453 //
5454 // We need to explicitly copy these referent objects - the references
5455 // will be processed at the end of remarking.
5456 //
5457 // We also need to do this copying before we process the reference
5458 // objects discovered by the STW ref processor in case one of these
5459 // referents points to another object which is also referenced by an
5460 // object discovered by the STW ref processor.
5461
5462 uint no_of_gc_workers = workers()->active_workers();
5463
5464 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5465 no_of_gc_workers,
5466 _task_queues);
5467
5468 workers()->run_task(&keep_cm_referents);
5469
5470 // Closure to test whether a referent is alive.
5471 G1STWIsAliveClosure is_alive(this);
5472
5473 // Even when parallel reference processing is enabled, the processing
5474 // of JNI refs is serial and performed serially by the current thread
5475 // rather than by a worker. The following PSS will be used for processing
5476 // JNI refs.
5477
5478 // Use only a single queue for this PSS.
5479 G1ParScanThreadState pss(this, 0, NULL);
5480
5481 // We do not embed a reference processor in the copying/scanning
5482 // closures while we're actually processing the discovered
5483 // reference objects.
5484 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5485
5486 pss.set_evac_failure_closure(&evac_failure_cl);
5487
5488 assert(pss.queue_is_empty(), "pre-condition");
5489
5490 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5491
5492 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5493
5494 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5495
5496 if (collector_state()->during_initial_mark_pause()) {
5497 // We also need to mark copied objects.
5498 copy_non_heap_cl = ©_mark_non_heap_cl;
5499 }
5500
5501 // Keep alive closure.
5502 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5503
5504 // Serial Complete GC closure
5505 G1STWDrainQueueClosure drain_queue(this, &pss);
5506
5507 // Setup the soft refs policy...
5508 rp->setup_policy(false);
5509
5510 ReferenceProcessorStats stats;
5511 if (!rp->processing_is_mt()) {
5512 // Serial reference processing...
5513 stats = rp->process_discovered_references(&is_alive,
5514 &keep_alive,
5515 &drain_queue,
5516 NULL,
5517 _gc_timer_stw,
5518 _gc_tracer_stw->gc_id());
5519 } else {
5520 // Parallel reference processing
5521 assert(rp->num_q() == no_of_gc_workers, "sanity");
5522 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5523
5524 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5525 stats = rp->process_discovered_references(&is_alive,
5526 &keep_alive,
5527 &drain_queue,
5528 &par_task_executor,
5529 _gc_timer_stw,
5530 _gc_tracer_stw->gc_id());
5531 }
5532
5533 _gc_tracer_stw->report_gc_reference_stats(stats);
5534
5535 // We have completed copying any necessary live referent objects.
5536 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5537
5538 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5539 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5540 }
5541
5542 // Weak Reference processing during an evacuation pause (part 2).
5543 void G1CollectedHeap::enqueue_discovered_references() {
5544 double ref_enq_start = os::elapsedTime();
5545
5546 ReferenceProcessor* rp = _ref_processor_stw;
5547 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5548
5549 // Now enqueue any remaining on the discovered lists on to
5550 // the pending list.
5551 if (!rp->processing_is_mt()) {
5552 // Serial reference processing...
5553 rp->enqueue_discovered_references();
5554 } else {
5555 // Parallel reference enqueueing
5556
5557 uint n_workers = workers()->active_workers();
5558
5559 assert(rp->num_q() == n_workers, "sanity");
5560 assert(n_workers <= rp->max_num_q(), "sanity");
5561
5562 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5563 rp->enqueue_discovered_references(&par_task_executor);
5564 }
5565
5566 rp->verify_no_references_recorded();
5567 assert(!rp->discovery_enabled(), "should have been disabled");
5568
5569 // FIXME
5570 // CM's reference processing also cleans up the string and symbol tables.
5571 // Should we do that here also? We could, but it is a serial operation
5572 // and could significantly increase the pause time.
5573
5574 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5575 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5576 }
5577
5578 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5579 _expand_heap_after_alloc_failure = true;
5580 _evacuation_failed = false;
5581
5582 // Should G1EvacuationFailureALot be in effect for this GC?
5583 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5584
5585 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5586
5587 // Disable the hot card cache.
5588 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5589 hot_card_cache->reset_hot_cache_claimed_index();
5590 hot_card_cache->set_use_cache(false);
5591
5592 const uint n_workers = workers()->active_workers();
5593
5594 init_for_evac_failure(NULL);
5595
5596 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5597 double start_par_time_sec = os::elapsedTime();
5598 double end_par_time_sec;
5599
5600 {
5601 G1RootProcessor root_processor(this, n_workers);
5602 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5603 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5604 if (collector_state()->during_initial_mark_pause()) {
5605 ClassLoaderDataGraph::clear_claimed_marks();
5606 }
5607
5608 // The individual threads will set their evac-failure closures.
5609 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5610
5611 workers()->run_task(&g1_par_task);
5612 end_par_time_sec = os::elapsedTime();
5613
5614 // Closing the inner scope will execute the destructor
5615 // for the G1RootProcessor object. We record the current
5616 // elapsed time before closing the scope so that time
5617 // taken for the destructor is NOT included in the
5618 // reported parallel time.
5619 }
5620
5621 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5622
5623 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5624 phase_times->record_par_time(par_time_ms);
5625
5626 double code_root_fixup_time_ms =
5627 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5628 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5629
5630 // Process any discovered reference objects - we have
5631 // to do this _before_ we retire the GC alloc regions
5632 // as we may have to copy some 'reachable' referent
5633 // objects (and their reachable sub-graphs) that were
5634 // not copied during the pause.
5635 process_discovered_references();
5636
5637 if (G1StringDedup::is_enabled()) {
5638 double fixup_start = os::elapsedTime();
5639
5640 G1STWIsAliveClosure is_alive(this);
5641 G1KeepAliveClosure keep_alive(this);
5642 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5643
5644 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5645 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5646 }
5647
5648 _allocator->release_gc_alloc_regions(evacuation_info);
5649 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5650
5651 // Reset and re-enable the hot card cache.
5652 // Note the counts for the cards in the regions in the
5653 // collection set are reset when the collection set is freed.
5654 hot_card_cache->reset_hot_cache();
5655 hot_card_cache->set_use_cache(true);
5656
5657 purge_code_root_memory();
5658
5659 finalize_for_evac_failure();
5660
5661 if (evacuation_failed()) {
5662 remove_self_forwarding_pointers();
5663
5664 // Reset the G1EvacuationFailureALot counters and flags
5665 // Note: the values are reset only when an actual
5666 // evacuation failure occurs.
5667 NOT_PRODUCT(reset_evacuation_should_fail();)
5668 }
5669
5670 // Enqueue any remaining references remaining on the STW
5671 // reference processor's discovered lists. We need to do
5672 // this after the card table is cleaned (and verified) as
5673 // the act of enqueueing entries on to the pending list
5674 // will log these updates (and dirty their associated
5675 // cards). We need these updates logged to update any
5676 // RSets.
5677 enqueue_discovered_references();
5678
5679 redirty_logged_cards();
5680 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5681 }
5682
5683 void G1CollectedHeap::free_region(HeapRegion* hr,
5684 FreeRegionList* free_list,
5685 bool par,
5686 bool locked) {
5687 assert(!hr->is_free(), "the region should not be free");
5688 assert(!hr->is_empty(), "the region should not be empty");
5689 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5690 assert(free_list != NULL, "pre-condition");
5691
5692 if (G1VerifyBitmaps) {
5693 MemRegion mr(hr->bottom(), hr->end());
5694 concurrent_mark()->clearRangePrevBitmap(mr);
5695 }
5696
5697 // Clear the card counts for this region.
5698 // Note: we only need to do this if the region is not young
5699 // (since we don't refine cards in young regions).
5700 if (!hr->is_young()) {
5701 _cg1r->hot_card_cache()->reset_card_counts(hr);
5702 }
5703 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5704 free_list->add_ordered(hr);
5705 }
5706
5707 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5708 FreeRegionList* free_list,
5709 bool par) {
5710 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5711 assert(free_list != NULL, "pre-condition");
5712
5713 size_t hr_capacity = hr->capacity();
5714 // We need to read this before we make the region non-humongous,
5715 // otherwise the information will be gone.
5716 uint last_index = hr->last_hc_index();
5717 hr->clear_humongous();
5718 free_region(hr, free_list, par);
5719
5720 uint i = hr->hrm_index() + 1;
5721 while (i < last_index) {
5722 HeapRegion* curr_hr = region_at(i);
5723 assert(curr_hr->is_continues_humongous(), "invariant");
5724 curr_hr->clear_humongous();
5725 free_region(curr_hr, free_list, par);
5726 i += 1;
5727 }
5728 }
5729
5730 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5731 const HeapRegionSetCount& humongous_regions_removed) {
5732 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5733 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5734 _old_set.bulk_remove(old_regions_removed);
5735 _humongous_set.bulk_remove(humongous_regions_removed);
5736 }
5737
5738 }
5739
5740 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5741 assert(list != NULL, "list can't be null");
5742 if (!list->is_empty()) {
5743 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5744 _hrm.insert_list_into_free_list(list);
5745 }
5746 }
5747
5748 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5749 decrease_used(bytes);
5750 }
5751
5752 class G1ParCleanupCTTask : public AbstractGangTask {
5753 G1SATBCardTableModRefBS* _ct_bs;
5754 G1CollectedHeap* _g1h;
5755 HeapRegion* volatile _su_head;
5756 public:
5757 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5758 G1CollectedHeap* g1h) :
5759 AbstractGangTask("G1 Par Cleanup CT Task"),
5760 _ct_bs(ct_bs), _g1h(g1h) { }
5761
5762 void work(uint worker_id) {
5763 HeapRegion* r;
5764 while (r = _g1h->pop_dirty_cards_region()) {
5765 clear_cards(r);
5766 }
5767 }
5768
5769 void clear_cards(HeapRegion* r) {
5770 // Cards of the survivors should have already been dirtied.
5771 if (!r->is_survivor()) {
5772 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5773 }
5774 }
5775 };
5776
5777 #ifndef PRODUCT
5778 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5779 G1CollectedHeap* _g1h;
5780 G1SATBCardTableModRefBS* _ct_bs;
5781 public:
5782 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5783 : _g1h(g1h), _ct_bs(ct_bs) { }
5784 virtual bool doHeapRegion(HeapRegion* r) {
5785 if (r->is_survivor()) {
5786 _g1h->verify_dirty_region(r);
5787 } else {
5788 _g1h->verify_not_dirty_region(r);
5789 }
5790 return false;
5791 }
5792 };
5793
5794 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5795 // All of the region should be clean.
5796 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5797 MemRegion mr(hr->bottom(), hr->end());
5798 ct_bs->verify_not_dirty_region(mr);
5799 }
5800
5801 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5802 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5803 // dirty allocated blocks as they allocate them. The thread that
5804 // retires each region and replaces it with a new one will do a
5805 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5806 // not dirty that area (one less thing to have to do while holding
5807 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5808 // is dirty.
5809 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5810 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5811 if (hr->is_young()) {
5812 ct_bs->verify_g1_young_region(mr);
5813 } else {
5814 ct_bs->verify_dirty_region(mr);
5815 }
5816 }
5817
5818 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5819 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5820 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5821 verify_dirty_region(hr);
5822 }
5823 }
5824
5825 void G1CollectedHeap::verify_dirty_young_regions() {
5826 verify_dirty_young_list(_young_list->first_region());
5827 }
5828
5829 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5830 HeapWord* tams, HeapWord* end) {
5831 guarantee(tams <= end,
5832 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5833 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5834 if (result < end) {
5835 gclog_or_tty->cr();
5836 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5837 bitmap_name, p2i(result));
5838 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5839 bitmap_name, p2i(tams), p2i(end));
5840 return false;
5841 }
5842 return true;
5843 }
5844
5845 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5846 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5847 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5848
5849 HeapWord* bottom = hr->bottom();
5850 HeapWord* ptams = hr->prev_top_at_mark_start();
5851 HeapWord* ntams = hr->next_top_at_mark_start();
5852 HeapWord* end = hr->end();
5853
5854 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5855
5856 bool res_n = true;
5857 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5858 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5859 // if we happen to be in that state.
5860 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5861 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5862 }
5863 if (!res_p || !res_n) {
5864 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5865 HR_FORMAT_PARAMS(hr));
5866 gclog_or_tty->print_cr("#### Caller: %s", caller);
5867 return false;
5868 }
5869 return true;
5870 }
5871
5872 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5873 if (!G1VerifyBitmaps) return;
5874
5875 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5876 }
5877
5878 class G1VerifyBitmapClosure : public HeapRegionClosure {
5879 private:
5880 const char* _caller;
5881 G1CollectedHeap* _g1h;
5882 bool _failures;
5883
5884 public:
5885 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5886 _caller(caller), _g1h(g1h), _failures(false) { }
5887
5888 bool failures() { return _failures; }
5889
5890 virtual bool doHeapRegion(HeapRegion* hr) {
5891 if (hr->is_continues_humongous()) return false;
5892
5893 bool result = _g1h->verify_bitmaps(_caller, hr);
5894 if (!result) {
5895 _failures = true;
5896 }
5897 return false;
5898 }
5899 };
5900
5901 void G1CollectedHeap::check_bitmaps(const char* caller) {
5902 if (!G1VerifyBitmaps) return;
5903
5904 G1VerifyBitmapClosure cl(caller, this);
5905 heap_region_iterate(&cl);
5906 guarantee(!cl.failures(), "bitmap verification");
5907 }
5908
5909 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5910 private:
5911 bool _failures;
5912 public:
5913 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5914
5915 virtual bool doHeapRegion(HeapRegion* hr) {
5916 uint i = hr->hrm_index();
5917 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5918 if (hr->is_humongous()) {
5919 if (hr->in_collection_set()) {
5920 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5921 _failures = true;
5922 return true;
5923 }
5924 if (cset_state.is_in_cset()) {
5925 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5926 _failures = true;
5927 return true;
5928 }
5929 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5930 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5931 _failures = true;
5932 return true;
5933 }
5934 } else {
5935 if (cset_state.is_humongous()) {
5936 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5937 _failures = true;
5938 return true;
5939 }
5940 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5941 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5942 hr->in_collection_set(), cset_state.value(), i);
5943 _failures = true;
5944 return true;
5945 }
5946 if (cset_state.is_in_cset()) {
5947 if (hr->is_young() != (cset_state.is_young())) {
5948 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5949 hr->is_young(), cset_state.value(), i);
5950 _failures = true;
5951 return true;
5952 }
5953 if (hr->is_old() != (cset_state.is_old())) {
5954 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5955 hr->is_old(), cset_state.value(), i);
5956 _failures = true;
5957 return true;
5958 }
5959 }
5960 }
5961 return false;
5962 }
5963
5964 bool failures() const { return _failures; }
5965 };
5966
5967 bool G1CollectedHeap::check_cset_fast_test() {
5968 G1CheckCSetFastTableClosure cl;
5969 _hrm.iterate(&cl);
5970 return !cl.failures();
5971 }
5972 #endif // PRODUCT
5973
5974 void G1CollectedHeap::cleanUpCardTable() {
5975 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5976 double start = os::elapsedTime();
5977
5978 {
5979 // Iterate over the dirty cards region list.
5980 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5981
5982 workers()->run_task(&cleanup_task);
5983 #ifndef PRODUCT
5984 if (G1VerifyCTCleanup || VerifyAfterGC) {
5985 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5986 heap_region_iterate(&cleanup_verifier);
5987 }
5988 #endif
5989 }
5990
5991 double elapsed = os::elapsedTime() - start;
5992 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5993 }
5994
5995 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5996 size_t pre_used = 0;
5997 FreeRegionList local_free_list("Local List for CSet Freeing");
5998
5999 double young_time_ms = 0.0;
6000 double non_young_time_ms = 0.0;
6001
6002 // Since the collection set is a superset of the the young list,
6003 // all we need to do to clear the young list is clear its
6004 // head and length, and unlink any young regions in the code below
6005 _young_list->clear();
6006
6007 G1CollectorPolicy* policy = g1_policy();
6008
6009 double start_sec = os::elapsedTime();
6010 bool non_young = true;
6011
6012 HeapRegion* cur = cs_head;
6013 int age_bound = -1;
6014 size_t rs_lengths = 0;
6015
6016 while (cur != NULL) {
6017 assert(!is_on_master_free_list(cur), "sanity");
6018 if (non_young) {
6019 if (cur->is_young()) {
6020 double end_sec = os::elapsedTime();
6021 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6022 non_young_time_ms += elapsed_ms;
6023
6024 start_sec = os::elapsedTime();
6025 non_young = false;
6026 }
6027 } else {
6028 if (!cur->is_young()) {
6029 double end_sec = os::elapsedTime();
6030 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6031 young_time_ms += elapsed_ms;
6032
6033 start_sec = os::elapsedTime();
6034 non_young = true;
6035 }
6036 }
6037
6038 rs_lengths += cur->rem_set()->occupied_locked();
6039
6040 HeapRegion* next = cur->next_in_collection_set();
6041 assert(cur->in_collection_set(), "bad CS");
6042 cur->set_next_in_collection_set(NULL);
6043 clear_in_cset(cur);
6044
6045 if (cur->is_young()) {
6046 int index = cur->young_index_in_cset();
6047 assert(index != -1, "invariant");
6048 assert((uint) index < policy->young_cset_region_length(), "invariant");
6049 size_t words_survived = _surviving_young_words[index];
6050 cur->record_surv_words_in_group(words_survived);
6051
6052 // At this point the we have 'popped' cur from the collection set
6053 // (linked via next_in_collection_set()) but it is still in the
6054 // young list (linked via next_young_region()). Clear the
6055 // _next_young_region field.
6056 cur->set_next_young_region(NULL);
6057 } else {
6058 int index = cur->young_index_in_cset();
6059 assert(index == -1, "invariant");
6060 }
6061
6062 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6063 (!cur->is_young() && cur->young_index_in_cset() == -1),
6064 "invariant" );
6065
6066 if (!cur->evacuation_failed()) {
6067 MemRegion used_mr = cur->used_region();
6068
6069 // And the region is empty.
6070 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6071 pre_used += cur->used();
6072 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6073 } else {
6074 cur->uninstall_surv_rate_group();
6075 if (cur->is_young()) {
6076 cur->set_young_index_in_cset(-1);
6077 }
6078 cur->set_evacuation_failed(false);
6079 // The region is now considered to be old.
6080 cur->set_old();
6081 _old_set.add(cur);
6082 evacuation_info.increment_collectionset_used_after(cur->used());
6083 }
6084 cur = next;
6085 }
6086
6087 evacuation_info.set_regions_freed(local_free_list.length());
6088 policy->record_max_rs_lengths(rs_lengths);
6089 policy->cset_regions_freed();
6090
6091 double end_sec = os::elapsedTime();
6092 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6093
6094 if (non_young) {
6095 non_young_time_ms += elapsed_ms;
6096 } else {
6097 young_time_ms += elapsed_ms;
6098 }
6099
6100 prepend_to_freelist(&local_free_list);
6101 decrement_summary_bytes(pre_used);
6102 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6103 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6104 }
6105
6106 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6107 private:
6108 FreeRegionList* _free_region_list;
6109 HeapRegionSet* _proxy_set;
6110 HeapRegionSetCount _humongous_regions_removed;
6111 size_t _freed_bytes;
6112 public:
6113
6114 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6115 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6116 }
6117
6118 virtual bool doHeapRegion(HeapRegion* r) {
6119 if (!r->is_starts_humongous()) {
6120 return false;
6121 }
6122
6123 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6124
6125 oop obj = (oop)r->bottom();
6126 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6127
6128 // The following checks whether the humongous object is live are sufficient.
6129 // The main additional check (in addition to having a reference from the roots
6130 // or the young gen) is whether the humongous object has a remembered set entry.
6131 //
6132 // A humongous object cannot be live if there is no remembered set for it
6133 // because:
6134 // - there can be no references from within humongous starts regions referencing
6135 // the object because we never allocate other objects into them.
6136 // (I.e. there are no intra-region references that may be missed by the
6137 // remembered set)
6138 // - as soon there is a remembered set entry to the humongous starts region
6139 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6140 // until the end of a concurrent mark.
6141 //
6142 // It is not required to check whether the object has been found dead by marking
6143 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6144 // all objects allocated during that time are considered live.
6145 // SATB marking is even more conservative than the remembered set.
6146 // So if at this point in the collection there is no remembered set entry,
6147 // nobody has a reference to it.
6148 // At the start of collection we flush all refinement logs, and remembered sets
6149 // are completely up-to-date wrt to references to the humongous object.
6150 //
6151 // Other implementation considerations:
6152 // - never consider object arrays at this time because they would pose
6153 // considerable effort for cleaning up the the remembered sets. This is
6154 // required because stale remembered sets might reference locations that
6155 // are currently allocated into.
6156 uint region_idx = r->hrm_index();
6157 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6158 !r->rem_set()->is_empty()) {
6159
6160 if (G1TraceEagerReclaimHumongousObjects) {
6161 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",
6162 region_idx,
6163 (size_t)obj->size() * HeapWordSize,
6164 p2i(r->bottom()),
6165 r->region_num(),
6166 r->rem_set()->occupied(),
6167 r->rem_set()->strong_code_roots_list_length(),
6168 next_bitmap->isMarked(r->bottom()),
6169 g1h->is_humongous_reclaim_candidate(region_idx),
6170 obj->is_typeArray()
6171 );
6172 }
6173
6174 return false;
6175 }
6176
6177 guarantee(obj->is_typeArray(),
6178 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6179 PTR_FORMAT " is not.",
6180 p2i(r->bottom())));
6181
6182 if (G1TraceEagerReclaimHumongousObjects) {
6183 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",
6184 region_idx,
6185 (size_t)obj->size() * HeapWordSize,
6186 p2i(r->bottom()),
6187 r->region_num(),
6188 r->rem_set()->occupied(),
6189 r->rem_set()->strong_code_roots_list_length(),
6190 next_bitmap->isMarked(r->bottom()),
6191 g1h->is_humongous_reclaim_candidate(region_idx),
6192 obj->is_typeArray()
6193 );
6194 }
6195 // Need to clear mark bit of the humongous object if already set.
6196 if (next_bitmap->isMarked(r->bottom())) {
6197 next_bitmap->clear(r->bottom());
6198 }
6199 _freed_bytes += r->used();
6200 r->set_containing_set(NULL);
6201 _humongous_regions_removed.increment(1u, r->capacity());
6202 g1h->free_humongous_region(r, _free_region_list, false);
6203
6204 return false;
6205 }
6206
6207 HeapRegionSetCount& humongous_free_count() {
6208 return _humongous_regions_removed;
6209 }
6210
6211 size_t bytes_freed() const {
6212 return _freed_bytes;
6213 }
6214
6215 size_t humongous_reclaimed() const {
6216 return _humongous_regions_removed.length();
6217 }
6218 };
6219
6220 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6221 assert_at_safepoint(true);
6222
6223 if (!G1EagerReclaimHumongousObjects ||
6224 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6225 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6226 return;
6227 }
6228
6229 double start_time = os::elapsedTime();
6230
6231 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6232
6233 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6234 heap_region_iterate(&cl);
6235
6236 HeapRegionSetCount empty_set;
6237 remove_from_old_sets(empty_set, cl.humongous_free_count());
6238
6239 G1HRPrinter* hrp = hr_printer();
6240 if (hrp->is_active()) {
6241 FreeRegionListIterator iter(&local_cleanup_list);
6242 while (iter.more_available()) {
6243 HeapRegion* hr = iter.get_next();
6244 hrp->cleanup(hr);
6245 }
6246 }
6247
6248 prepend_to_freelist(&local_cleanup_list);
6249 decrement_summary_bytes(cl.bytes_freed());
6250
6251 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6252 cl.humongous_reclaimed());
6253 }
6254
6255 // This routine is similar to the above but does not record
6256 // any policy statistics or update free lists; we are abandoning
6257 // the current incremental collection set in preparation of a
6258 // full collection. After the full GC we will start to build up
6259 // the incremental collection set again.
6260 // This is only called when we're doing a full collection
6261 // and is immediately followed by the tearing down of the young list.
6262
6263 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6264 HeapRegion* cur = cs_head;
6265
6266 while (cur != NULL) {
6267 HeapRegion* next = cur->next_in_collection_set();
6268 assert(cur->in_collection_set(), "bad CS");
6269 cur->set_next_in_collection_set(NULL);
6270 clear_in_cset(cur);
6271 cur->set_young_index_in_cset(-1);
6272 cur = next;
6273 }
6274 }
6275
6276 void G1CollectedHeap::set_free_regions_coming() {
6277 if (G1ConcRegionFreeingVerbose) {
6278 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6279 "setting free regions coming");
6280 }
6281
6282 assert(!free_regions_coming(), "pre-condition");
6283 _free_regions_coming = true;
6284 }
6285
6286 void G1CollectedHeap::reset_free_regions_coming() {
6287 assert(free_regions_coming(), "pre-condition");
6288
6289 {
6290 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6291 _free_regions_coming = false;
6292 SecondaryFreeList_lock->notify_all();
6293 }
6294
6295 if (G1ConcRegionFreeingVerbose) {
6296 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6297 "reset free regions coming");
6298 }
6299 }
6300
6301 void G1CollectedHeap::wait_while_free_regions_coming() {
6302 // Most of the time we won't have to wait, so let's do a quick test
6303 // first before we take the lock.
6304 if (!free_regions_coming()) {
6305 return;
6306 }
6307
6308 if (G1ConcRegionFreeingVerbose) {
6309 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6310 "waiting for free regions");
6311 }
6312
6313 {
6314 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6315 while (free_regions_coming()) {
6316 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6317 }
6318 }
6319
6320 if (G1ConcRegionFreeingVerbose) {
6321 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6322 "done waiting for free regions");
6323 }
6324 }
6325
6326 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6327 _young_list->push_region(hr);
6328 }
6329
6330 class NoYoungRegionsClosure: public HeapRegionClosure {
6331 private:
6332 bool _success;
6333 public:
6334 NoYoungRegionsClosure() : _success(true) { }
6335 bool doHeapRegion(HeapRegion* r) {
6336 if (r->is_young()) {
6337 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6338 p2i(r->bottom()), p2i(r->end()));
6339 _success = false;
6340 }
6341 return false;
6342 }
6343 bool success() { return _success; }
6344 };
6345
6346 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6347 bool ret = _young_list->check_list_empty(check_sample);
6348
6349 if (check_heap) {
6350 NoYoungRegionsClosure closure;
6351 heap_region_iterate(&closure);
6352 ret = ret && closure.success();
6353 }
6354
6355 return ret;
6356 }
6357
6358 class TearDownRegionSetsClosure : public HeapRegionClosure {
6359 private:
6360 HeapRegionSet *_old_set;
6361
6362 public:
6363 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6364
6365 bool doHeapRegion(HeapRegion* r) {
6366 if (r->is_old()) {
6367 _old_set->remove(r);
6368 } else {
6369 // We ignore free regions, we'll empty the free list afterwards.
6370 // We ignore young regions, we'll empty the young list afterwards.
6371 // We ignore humongous regions, we're not tearing down the
6372 // humongous regions set.
6373 assert(r->is_free() || r->is_young() || r->is_humongous(),
6374 "it cannot be another type");
6375 }
6376 return false;
6377 }
6378
6379 ~TearDownRegionSetsClosure() {
6380 assert(_old_set->is_empty(), "post-condition");
6381 }
6382 };
6383
6384 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6385 assert_at_safepoint(true /* should_be_vm_thread */);
6386
6387 if (!free_list_only) {
6388 TearDownRegionSetsClosure cl(&_old_set);
6389 heap_region_iterate(&cl);
6390
6391 // Note that emptying the _young_list is postponed and instead done as
6392 // the first step when rebuilding the regions sets again. The reason for
6393 // this is that during a full GC string deduplication needs to know if
6394 // a collected region was young or old when the full GC was initiated.
6395 }
6396 _hrm.remove_all_free_regions();
6397 }
6398
6399 void G1CollectedHeap::increase_used(size_t bytes) {
6400 _summary_bytes_used += bytes;
6401 }
6402
6403 void G1CollectedHeap::decrease_used(size_t bytes) {
6404 assert(_summary_bytes_used >= bytes,
6405 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6406 _summary_bytes_used, bytes));
6407 _summary_bytes_used -= bytes;
6408 }
6409
6410 void G1CollectedHeap::set_used(size_t bytes) {
6411 _summary_bytes_used = bytes;
6412 }
6413
6414 class RebuildRegionSetsClosure : public HeapRegionClosure {
6415 private:
6416 bool _free_list_only;
6417 HeapRegionSet* _old_set;
6418 HeapRegionManager* _hrm;
6419 size_t _total_used;
6420
6421 public:
6422 RebuildRegionSetsClosure(bool free_list_only,
6423 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6424 _free_list_only(free_list_only),
6425 _old_set(old_set), _hrm(hrm), _total_used(0) {
6426 assert(_hrm->num_free_regions() == 0, "pre-condition");
6427 if (!free_list_only) {
6428 assert(_old_set->is_empty(), "pre-condition");
6429 }
6430 }
6431
6432 bool doHeapRegion(HeapRegion* r) {
6433 if (r->is_continues_humongous()) {
6434 return false;
6435 }
6436
6437 if (r->is_empty()) {
6438 // Add free regions to the free list
6439 r->set_free();
6440 r->set_allocation_context(AllocationContext::system());
6441 _hrm->insert_into_free_list(r);
6442 } else if (!_free_list_only) {
6443 assert(!r->is_young(), "we should not come across young regions");
6444
6445 if (r->is_humongous()) {
6446 // We ignore humongous regions. We left the humongous set unchanged.
6447 } else {
6448 // Objects that were compacted would have ended up on regions
6449 // that were previously old or free. Archive regions (which are
6450 // old) will not have been touched.
6451 assert(r->is_free() || r->is_old(), "invariant");
6452 // We now consider them old, so register as such. Leave
6453 // archive regions set that way, however, while still adding
6454 // them to the old set.
6455 if (!r->is_archive()) {
6456 r->set_old();
6457 }
6458 _old_set->add(r);
6459 }
6460 _total_used += r->used();
6461 }
6462
6463 return false;
6464 }
6465
6466 size_t total_used() {
6467 return _total_used;
6468 }
6469 };
6470
6471 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6472 assert_at_safepoint(true /* should_be_vm_thread */);
6473
6474 if (!free_list_only) {
6475 _young_list->empty_list();
6476 }
6477
6478 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6479 heap_region_iterate(&cl);
6480
6481 if (!free_list_only) {
6482 set_used(cl.total_used());
6483 if (_archive_allocator != NULL) {
6484 _archive_allocator->clear_used();
6485 }
6486 }
6487 assert(used_unlocked() == recalculate_used(),
6488 err_msg("inconsistent used_unlocked(), "
6489 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6490 used_unlocked(), recalculate_used()));
6491 }
6492
6493 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6494 _refine_cte_cl->set_concurrent(concurrent);
6495 }
6496
6497 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6498 HeapRegion* hr = heap_region_containing(p);
6499 return hr->is_in(p);
6500 }
6501
6502 // Methods for the mutator alloc region
6503
6504 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6505 bool force) {
6506 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6507 assert(!force || g1_policy()->can_expand_young_list(),
6508 "if force is true we should be able to expand the young list");
6509 bool young_list_full = g1_policy()->is_young_list_full();
6510 if (force || !young_list_full) {
6511 HeapRegion* new_alloc_region = new_region(word_size,
6512 false /* is_old */,
6513 false /* do_expand */);
6514 if (new_alloc_region != NULL) {
6515 set_region_short_lived_locked(new_alloc_region);
6516 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6517 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6518 return new_alloc_region;
6519 }
6520 }
6521 return NULL;
6522 }
6523
6524 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6525 size_t allocated_bytes) {
6526 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6527 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6528
6529 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6530 increase_used(allocated_bytes);
6531 _hr_printer.retire(alloc_region);
6532 // We update the eden sizes here, when the region is retired,
6533 // instead of when it's allocated, since this is the point that its
6534 // used space has been recored in _summary_bytes_used.
6535 g1mm()->update_eden_size();
6536 }
6537
6538 // Methods for the GC alloc regions
6539
6540 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6541 uint count,
6542 InCSetState dest) {
6543 assert(FreeList_lock->owned_by_self(), "pre-condition");
6544
6545 if (count < g1_policy()->max_regions(dest)) {
6546 const bool is_survivor = (dest.is_young());
6547 HeapRegion* new_alloc_region = new_region(word_size,
6548 !is_survivor,
6549 true /* do_expand */);
6550 if (new_alloc_region != NULL) {
6551 // We really only need to do this for old regions given that we
6552 // should never scan survivors. But it doesn't hurt to do it
6553 // for survivors too.
6554 new_alloc_region->record_timestamp();
6555 if (is_survivor) {
6556 new_alloc_region->set_survivor();
6557 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6558 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6559 } else {
6560 new_alloc_region->set_old();
6561 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6562 check_bitmaps("Old Region Allocation", new_alloc_region);
6563 }
6564 bool during_im = collector_state()->during_initial_mark_pause();
6565 new_alloc_region->note_start_of_copying(during_im);
6566 return new_alloc_region;
6567 }
6568 }
6569 return NULL;
6570 }
6571
6572 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6573 size_t allocated_bytes,
6574 InCSetState dest) {
6575 bool during_im = collector_state()->during_initial_mark_pause();
6576 alloc_region->note_end_of_copying(during_im);
6577 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6578 if (dest.is_young()) {
6579 young_list()->add_survivor_region(alloc_region);
6580 } else {
6581 _old_set.add(alloc_region);
6582 }
6583 _hr_printer.retire(alloc_region);
6584 }
6585
6586 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6587 bool expanded = false;
6588 uint index = _hrm.find_highest_free(&expanded);
6589
6590 if (index != G1_NO_HRM_INDEX) {
6591 if (expanded) {
6592 ergo_verbose1(ErgoHeapSizing,
6593 "attempt heap expansion",
6594 ergo_format_reason("requested address range outside heap bounds")
6595 ergo_format_byte("region size"),
6596 HeapRegion::GrainWords * HeapWordSize);
6597 }
6598 _hrm.allocate_free_regions_starting_at(index, 1);
6599 return region_at(index);
6600 }
6601 return NULL;
6602 }
6603
6604
6605 // Heap region set verification
6606
6607 class VerifyRegionListsClosure : public HeapRegionClosure {
6608 private:
6609 HeapRegionSet* _old_set;
6610 HeapRegionSet* _humongous_set;
6611 HeapRegionManager* _hrm;
6612
6613 public:
6614 HeapRegionSetCount _old_count;
6615 HeapRegionSetCount _humongous_count;
6616 HeapRegionSetCount _free_count;
6617
6618 VerifyRegionListsClosure(HeapRegionSet* old_set,
6619 HeapRegionSet* humongous_set,
6620 HeapRegionManager* hrm) :
6621 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6622 _old_count(), _humongous_count(), _free_count(){ }
6623
6624 bool doHeapRegion(HeapRegion* hr) {
6625 if (hr->is_continues_humongous()) {
6626 return false;
6627 }
6628
6629 if (hr->is_young()) {
6630 // TODO
6631 } else if (hr->is_starts_humongous()) {
6632 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6633 _humongous_count.increment(1u, hr->capacity());
6634 } else if (hr->is_empty()) {
6635 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6636 _free_count.increment(1u, hr->capacity());
6637 } else if (hr->is_old()) {
6638 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6639 _old_count.increment(1u, hr->capacity());
6640 } else {
6641 // There are no other valid region types. Check for one invalid
6642 // one we can identify: pinned without old or humongous set.
6643 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6644 ShouldNotReachHere();
6645 }
6646 return false;
6647 }
6648
6649 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6650 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6651 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6652 old_set->total_capacity_bytes(), _old_count.capacity()));
6653
6654 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6655 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6656 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6657
6658 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()));
6659 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6660 free_list->total_capacity_bytes(), _free_count.capacity()));
6661 }
6662 };
6663
6664 void G1CollectedHeap::verify_region_sets() {
6665 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6666
6667 // First, check the explicit lists.
6668 _hrm.verify();
6669 {
6670 // Given that a concurrent operation might be adding regions to
6671 // the secondary free list we have to take the lock before
6672 // verifying it.
6673 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6674 _secondary_free_list.verify_list();
6675 }
6676
6677 // If a concurrent region freeing operation is in progress it will
6678 // be difficult to correctly attributed any free regions we come
6679 // across to the correct free list given that they might belong to
6680 // one of several (free_list, secondary_free_list, any local lists,
6681 // etc.). So, if that's the case we will skip the rest of the
6682 // verification operation. Alternatively, waiting for the concurrent
6683 // operation to complete will have a non-trivial effect on the GC's
6684 // operation (no concurrent operation will last longer than the
6685 // interval between two calls to verification) and it might hide
6686 // any issues that we would like to catch during testing.
6687 if (free_regions_coming()) {
6688 return;
6689 }
6690
6691 // Make sure we append the secondary_free_list on the free_list so
6692 // that all free regions we will come across can be safely
6693 // attributed to the free_list.
6694 append_secondary_free_list_if_not_empty_with_lock();
6695
6696 // Finally, make sure that the region accounting in the lists is
6697 // consistent with what we see in the heap.
6698
6699 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6700 heap_region_iterate(&cl);
6701 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6702 }
6703
6704 // Optimized nmethod scanning
6705
6706 class RegisterNMethodOopClosure: public OopClosure {
6707 G1CollectedHeap* _g1h;
6708 nmethod* _nm;
6709
6710 template <class T> void do_oop_work(T* p) {
6711 T heap_oop = oopDesc::load_heap_oop(p);
6712 if (!oopDesc::is_null(heap_oop)) {
6713 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6714 HeapRegion* hr = _g1h->heap_region_containing(obj);
6715 assert(!hr->is_continues_humongous(),
6716 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6717 " starting at " HR_FORMAT,
6718 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6719
6720 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6721 hr->add_strong_code_root_locked(_nm);
6722 }
6723 }
6724
6725 public:
6726 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6727 _g1h(g1h), _nm(nm) {}
6728
6729 void do_oop(oop* p) { do_oop_work(p); }
6730 void do_oop(narrowOop* p) { do_oop_work(p); }
6731 };
6732
6733 class UnregisterNMethodOopClosure: public OopClosure {
6734 G1CollectedHeap* _g1h;
6735 nmethod* _nm;
6736
6737 template <class T> void do_oop_work(T* p) {
6738 T heap_oop = oopDesc::load_heap_oop(p);
6739 if (!oopDesc::is_null(heap_oop)) {
6740 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6741 HeapRegion* hr = _g1h->heap_region_containing(obj);
6742 assert(!hr->is_continues_humongous(),
6743 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6744 " starting at " HR_FORMAT,
6745 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6746
6747 hr->remove_strong_code_root(_nm);
6748 }
6749 }
6750
6751 public:
6752 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6753 _g1h(g1h), _nm(nm) {}
6754
6755 void do_oop(oop* p) { do_oop_work(p); }
6756 void do_oop(narrowOop* p) { do_oop_work(p); }
6757 };
6758
6759 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6760 CollectedHeap::register_nmethod(nm);
6761
6762 guarantee(nm != NULL, "sanity");
6763 RegisterNMethodOopClosure reg_cl(this, nm);
6764 nm->oops_do(®_cl);
6765 }
6766
6767 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6768 CollectedHeap::unregister_nmethod(nm);
6769
6770 guarantee(nm != NULL, "sanity");
6771 UnregisterNMethodOopClosure reg_cl(this, nm);
6772 nm->oops_do(®_cl, true);
6773 }
6774
6775 void G1CollectedHeap::purge_code_root_memory() {
6776 double purge_start = os::elapsedTime();
6777 G1CodeRootSet::purge();
6778 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6779 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6780 }
6781
6782 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6783 G1CollectedHeap* _g1h;
6784
6785 public:
6786 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6787 _g1h(g1h) {}
6788
6789 void do_code_blob(CodeBlob* cb) {
6790 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6791 if (nm == NULL) {
6792 return;
6793 }
6794
6795 if (ScavengeRootsInCode) {
6796 _g1h->register_nmethod(nm);
6797 }
6798 }
6799 };
6800
6801 void G1CollectedHeap::rebuild_strong_code_roots() {
6802 RebuildStrongCodeRootClosure blob_cl(this);
6803 CodeCache::blobs_do(&blob_cl);
6804 }