1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "memory/allocation.hpp"
65 #include "memory/iterator.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/init.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72 #include "utilities/stack.inline.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // INVARIANTS/NOTES
77 //
78 // All allocation activity covered by the G1CollectedHeap interface is
79 // serialized by acquiring the HeapLock. This happens in mem_allocate
80 // and allocate_new_tlab, which are the "entry" points to the
81 // allocation code from the rest of the JVM. (Note that this does not
82 // apply to TLAB allocation, which is not part of this interface: it
83 // is done by clients of this interface.)
84
85 // Local to this file.
86
87 class RefineCardTableEntryClosure: public CardTableEntryClosure {
88 bool _concurrent;
89 public:
90 RefineCardTableEntryClosure() : _concurrent(true) { }
91
92 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
93 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
94 // This path is executed by the concurrent refine or mutator threads,
95 // concurrently, and so we do not care if card_ptr contains references
96 // that point into the collection set.
97 assert(!oops_into_cset, "should be");
98
99 if (_concurrent && SuspendibleThreadSet::should_yield()) {
100 // Caller will actually yield.
101 return false;
102 }
103 // Otherwise, we finished successfully; return true.
104 return true;
105 }
106
107 void set_concurrent(bool b) { _concurrent = b; }
108 };
109
110
111 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
112 private:
113 size_t _num_processed;
114
115 public:
116 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
117
118 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
119 *card_ptr = CardTableModRefBS::dirty_card_val();
120 _num_processed++;
121 return true;
122 }
123
124 size_t num_processed() const { return _num_processed; }
125 };
126
127 YoungList::YoungList(G1CollectedHeap* g1h) :
128 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
129 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
130 guarantee(check_list_empty(false), "just making sure...");
131 }
132
133 void YoungList::push_region(HeapRegion *hr) {
134 assert(!hr->is_young(), "should not already be young");
135 assert(hr->get_next_young_region() == NULL, "cause it should!");
136
137 hr->set_next_young_region(_head);
138 _head = hr;
139
140 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
141 ++_length;
142 }
143
144 void YoungList::add_survivor_region(HeapRegion* hr) {
145 assert(hr->is_survivor(), "should be flagged as survivor region");
146 assert(hr->get_next_young_region() == NULL, "cause it should!");
147
148 hr->set_next_young_region(_survivor_head);
149 if (_survivor_head == NULL) {
150 _survivor_tail = hr;
151 }
152 _survivor_head = hr;
153 ++_survivor_length;
154 }
155
156 void YoungList::empty_list(HeapRegion* list) {
157 while (list != NULL) {
158 HeapRegion* next = list->get_next_young_region();
159 list->set_next_young_region(NULL);
160 list->uninstall_surv_rate_group();
161 // This is called before a Full GC and all the non-empty /
162 // non-humongous regions at the end of the Full GC will end up as
163 // old anyway.
164 list->set_old();
165 list = next;
166 }
167 }
168
169 void YoungList::empty_list() {
170 assert(check_list_well_formed(), "young list should be well formed");
171
172 empty_list(_head);
173 _head = NULL;
174 _length = 0;
175
176 empty_list(_survivor_head);
177 _survivor_head = NULL;
178 _survivor_tail = NULL;
179 _survivor_length = 0;
180
181 _last_sampled_rs_lengths = 0;
182
183 assert(check_list_empty(false), "just making sure...");
184 }
185
186 bool YoungList::check_list_well_formed() {
187 bool ret = true;
188
189 uint length = 0;
190 HeapRegion* curr = _head;
191 HeapRegion* last = NULL;
192 while (curr != NULL) {
193 if (!curr->is_young()) {
194 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
195 "incorrectly tagged (y: %d, surv: %d)",
196 p2i(curr->bottom()), p2i(curr->end()),
197 curr->is_young(), curr->is_survivor());
198 ret = false;
199 }
200 ++length;
201 last = curr;
202 curr = curr->get_next_young_region();
203 }
204 ret = ret && (length == _length);
205
206 if (!ret) {
207 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
208 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
209 length, _length);
210 }
211
212 return ret;
213 }
214
215 bool YoungList::check_list_empty(bool check_sample) {
216 bool ret = true;
217
218 if (_length != 0) {
219 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
220 _length);
221 ret = false;
222 }
223 if (check_sample && _last_sampled_rs_lengths != 0) {
224 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
225 ret = false;
226 }
227 if (_head != NULL) {
228 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
229 ret = false;
230 }
231 if (!ret) {
232 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
233 }
234
235 return ret;
236 }
237
238 void
239 YoungList::rs_length_sampling_init() {
240 _sampled_rs_lengths = 0;
241 _curr = _head;
242 }
243
244 bool
245 YoungList::rs_length_sampling_more() {
246 return _curr != NULL;
247 }
248
249 void
250 YoungList::rs_length_sampling_next() {
251 assert( _curr != NULL, "invariant" );
252 size_t rs_length = _curr->rem_set()->occupied();
253
254 _sampled_rs_lengths += rs_length;
255
256 // The current region may not yet have been added to the
257 // incremental collection set (it gets added when it is
258 // retired as the current allocation region).
259 if (_curr->in_collection_set()) {
260 // Update the collection set policy information for this region
261 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
262 }
263
264 _curr = _curr->get_next_young_region();
265 if (_curr == NULL) {
266 _last_sampled_rs_lengths = _sampled_rs_lengths;
267 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
268 }
269 }
270
271 void
272 YoungList::reset_auxilary_lists() {
273 guarantee( is_empty(), "young list should be empty" );
274 assert(check_list_well_formed(), "young list should be well formed");
275
276 // Add survivor regions to SurvRateGroup.
277 _g1h->g1_policy()->note_start_adding_survivor_regions();
278 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
279
280 int young_index_in_cset = 0;
281 for (HeapRegion* curr = _survivor_head;
282 curr != NULL;
283 curr = curr->get_next_young_region()) {
284 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
285
286 // The region is a non-empty survivor so let's add it to
287 // the incremental collection set for the next evacuation
288 // pause.
289 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
290 young_index_in_cset += 1;
291 }
292 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
293 _g1h->g1_policy()->note_stop_adding_survivor_regions();
294
295 _head = _survivor_head;
296 _length = _survivor_length;
297 if (_survivor_head != NULL) {
298 assert(_survivor_tail != NULL, "cause it shouldn't be");
299 assert(_survivor_length > 0, "invariant");
300 _survivor_tail->set_next_young_region(NULL);
301 }
302
303 // Don't clear the survivor list handles until the start of
304 // the next evacuation pause - we need it in order to re-tag
305 // the survivor regions from this evacuation pause as 'young'
306 // at the start of the next.
307
308 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
309
310 assert(check_list_well_formed(), "young list should be well formed");
311 }
312
313 void YoungList::print() {
314 HeapRegion* lists[] = {_head, _survivor_head};
315 const char* names[] = {"YOUNG", "SURVIVOR"};
316
317 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
318 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
319 HeapRegion *curr = lists[list];
320 if (curr == NULL)
321 gclog_or_tty->print_cr(" empty");
322 while (curr != NULL) {
323 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
324 HR_FORMAT_PARAMS(curr),
325 p2i(curr->prev_top_at_mark_start()),
326 p2i(curr->next_top_at_mark_start()),
327 curr->age_in_surv_rate_group_cond());
328 curr = curr->get_next_young_region();
329 }
330 }
331
332 gclog_or_tty->cr();
333 }
334
335 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
336 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
337 }
338
339 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
340 // The from card cache is not the memory that is actually committed. So we cannot
341 // take advantage of the zero_filled parameter.
342 reset_from_card_cache(start_idx, num_regions);
343 }
344
345 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
346 {
347 // Claim the right to put the region on the dirty cards region list
348 // by installing a self pointer.
349 HeapRegion* next = hr->get_next_dirty_cards_region();
350 if (next == NULL) {
351 HeapRegion* res = (HeapRegion*)
352 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
353 NULL);
354 if (res == NULL) {
355 HeapRegion* head;
356 do {
357 // Put the region to the dirty cards region list.
358 head = _dirty_cards_region_list;
359 next = (HeapRegion*)
360 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
361 if (next == head) {
362 assert(hr->get_next_dirty_cards_region() == hr,
363 "hr->get_next_dirty_cards_region() != hr");
364 if (next == NULL) {
365 // The last region in the list points to itself.
366 hr->set_next_dirty_cards_region(hr);
367 } else {
368 hr->set_next_dirty_cards_region(next);
369 }
370 }
371 } while (next != head);
372 }
373 }
374 }
375
376 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
377 {
378 HeapRegion* head;
379 HeapRegion* hr;
380 do {
381 head = _dirty_cards_region_list;
382 if (head == NULL) {
383 return NULL;
384 }
385 HeapRegion* new_head = head->get_next_dirty_cards_region();
386 if (head == new_head) {
387 // The last region.
388 new_head = NULL;
389 }
390 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
391 head);
392 } while (hr != head);
393 assert(hr != NULL, "invariant");
394 hr->set_next_dirty_cards_region(NULL);
395 return hr;
396 }
397
398 // Returns true if the reference points to an object that
399 // can move in an incremental collection.
400 bool G1CollectedHeap::is_scavengable(const void* p) {
401 HeapRegion* hr = heap_region_containing(p);
402 return !hr->is_pinned();
403 }
404
405 // Private methods.
406
407 HeapRegion*
408 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
409 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
410 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
411 if (!_secondary_free_list.is_empty()) {
412 if (G1ConcRegionFreeingVerbose) {
413 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
414 "secondary_free_list has %u entries",
415 _secondary_free_list.length());
416 }
417 // It looks as if there are free regions available on the
418 // secondary_free_list. Let's move them to the free_list and try
419 // again to allocate from it.
420 append_secondary_free_list();
421
422 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
423 "empty we should have moved at least one entry to the free_list");
424 HeapRegion* res = _hrm.allocate_free_region(is_old);
425 if (G1ConcRegionFreeingVerbose) {
426 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
427 "allocated " HR_FORMAT " from secondary_free_list",
428 HR_FORMAT_PARAMS(res));
429 }
430 return res;
431 }
432
433 // Wait here until we get notified either when (a) there are no
434 // more free regions coming or (b) some regions have been moved on
435 // the secondary_free_list.
436 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
437 }
438
439 if (G1ConcRegionFreeingVerbose) {
440 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
441 "could not allocate from secondary_free_list");
442 }
443 return NULL;
444 }
445
446 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
447 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
448 "the only time we use this to allocate a humongous region is "
449 "when we are allocating a single humongous region");
450
451 HeapRegion* res;
452 if (G1StressConcRegionFreeing) {
453 if (!_secondary_free_list.is_empty()) {
454 if (G1ConcRegionFreeingVerbose) {
455 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
456 "forced to look at the secondary_free_list");
457 }
458 res = new_region_try_secondary_free_list(is_old);
459 if (res != NULL) {
460 return res;
461 }
462 }
463 }
464
465 res = _hrm.allocate_free_region(is_old);
466
467 if (res == NULL) {
468 if (G1ConcRegionFreeingVerbose) {
469 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
470 "res == NULL, trying the secondary_free_list");
471 }
472 res = new_region_try_secondary_free_list(is_old);
473 }
474 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
475 // Currently, only attempts to allocate GC alloc regions set
476 // do_expand to true. So, we should only reach here during a
477 // safepoint. If this assumption changes we might have to
478 // reconsider the use of _expand_heap_after_alloc_failure.
479 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
480
481 ergo_verbose1(ErgoHeapSizing,
482 "attempt heap expansion",
483 ergo_format_reason("region allocation request failed")
484 ergo_format_byte("allocation request"),
485 word_size * HeapWordSize);
486 if (expand(word_size * HeapWordSize)) {
487 // Given that expand() succeeded in expanding the heap, and we
488 // always expand the heap by an amount aligned to the heap
489 // region size, the free list should in theory not be empty.
490 // In either case allocate_free_region() will check for NULL.
491 res = _hrm.allocate_free_region(is_old);
492 } else {
493 _expand_heap_after_alloc_failure = false;
494 }
495 }
496 return res;
497 }
498
499 HeapWord*
500 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
501 uint num_regions,
502 size_t word_size,
503 AllocationContext_t context) {
504 assert(first != G1_NO_HRM_INDEX, "pre-condition");
505 assert(is_humongous(word_size), "word_size should be humongous");
506 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
507
508 // Index of last region in the series + 1.
509 uint last = first + num_regions;
510
511 // We need to initialize the region(s) we just discovered. This is
512 // a bit tricky given that it can happen concurrently with
513 // refinement threads refining cards on these regions and
514 // potentially wanting to refine the BOT as they are scanning
515 // those cards (this can happen shortly after a cleanup; see CR
516 // 6991377). So we have to set up the region(s) carefully and in
517 // a specific order.
518
519 // The word size sum of all the regions we will allocate.
520 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
521 assert(word_size <= word_size_sum, "sanity");
522
523 // This will be the "starts humongous" region.
524 HeapRegion* first_hr = region_at(first);
525 // The header of the new object will be placed at the bottom of
526 // the first region.
527 HeapWord* new_obj = first_hr->bottom();
528 // This will be the new end of the first region in the series that
529 // should also match the end of the last region in the series.
530 HeapWord* new_end = new_obj + word_size_sum;
531 // This will be the new top of the first region that will reflect
532 // this allocation.
533 HeapWord* new_top = new_obj + word_size;
534
535 // First, we need to zero the header of the space that we will be
536 // allocating. When we update top further down, some refinement
537 // threads might try to scan the region. By zeroing the header we
538 // ensure that any thread that will try to scan the region will
539 // come across the zero klass word and bail out.
540 //
541 // NOTE: It would not have been correct to have used
542 // CollectedHeap::fill_with_object() and make the space look like
543 // an int array. The thread that is doing the allocation will
544 // later update the object header to a potentially different array
545 // type and, for a very short period of time, the klass and length
546 // fields will be inconsistent. This could cause a refinement
547 // thread to calculate the object size incorrectly.
548 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
549
550 // We will set up the first region as "starts humongous". This
551 // will also update the BOT covering all the regions to reflect
552 // that there is a single object that starts at the bottom of the
553 // first region.
554 first_hr->set_starts_humongous(new_top, new_end);
555 first_hr->set_allocation_context(context);
556 // Then, if there are any, we will set up the "continues
557 // humongous" regions.
558 HeapRegion* hr = NULL;
559 for (uint i = first + 1; i < last; ++i) {
560 hr = region_at(i);
561 hr->set_continues_humongous(first_hr);
562 hr->set_allocation_context(context);
563 }
564 // If we have "continues humongous" regions (hr != NULL), then the
565 // end of the last one should match new_end.
566 assert(hr == NULL || hr->end() == new_end, "sanity");
567
568 // Up to this point no concurrent thread would have been able to
569 // do any scanning on any region in this series. All the top
570 // fields still point to bottom, so the intersection between
571 // [bottom,top] and [card_start,card_end] will be empty. Before we
572 // update the top fields, we'll do a storestore to make sure that
573 // no thread sees the update to top before the zeroing of the
574 // object header and the BOT initialization.
575 OrderAccess::storestore();
576
577 // Now that the BOT and the object header have been initialized,
578 // we can update top of the "starts humongous" region.
579 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
580 "new_top should be in this region");
581 first_hr->set_top(new_top);
582 if (_hr_printer.is_active()) {
583 HeapWord* bottom = first_hr->bottom();
584 HeapWord* end = first_hr->orig_end();
585 if ((first + 1) == last) {
586 // the series has a single humongous region
587 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
588 } else {
589 // the series has more than one humongous regions
590 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
591 }
592 }
593
594 // Now, we will update the top fields of the "continues humongous"
595 // regions. The reason we need to do this is that, otherwise,
596 // these regions would look empty and this will confuse parts of
597 // G1. For example, the code that looks for a consecutive number
598 // of empty regions will consider them empty and try to
599 // re-allocate them. We can extend is_empty() to also include
600 // !is_continues_humongous(), but it is easier to just update the top
601 // fields here. The way we set top for all regions (i.e., top ==
602 // end for all regions but the last one, top == new_top for the
603 // last one) is actually used when we will free up the humongous
604 // region in free_humongous_region().
605 hr = NULL;
606 for (uint i = first + 1; i < last; ++i) {
607 hr = region_at(i);
608 if ((i + 1) == last) {
609 // last continues humongous region
610 assert(hr->bottom() < new_top && new_top <= hr->end(),
611 "new_top should fall on this region");
612 hr->set_top(new_top);
613 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
614 } else {
615 // not last one
616 assert(new_top > hr->end(), "new_top should be above this region");
617 hr->set_top(hr->end());
618 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
619 }
620 }
621 // If we have continues humongous regions (hr != NULL), then the
622 // end of the last one should match new_end and its top should
623 // match new_top.
624 assert(hr == NULL ||
625 (hr->end() == new_end && hr->top() == new_top), "sanity");
626 check_bitmaps("Humongous Region Allocation", first_hr);
627
628 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
629 increase_used(first_hr->used());
630 _humongous_set.add(first_hr);
631
632 return new_obj;
633 }
634
635 // If could fit into free regions w/o expansion, try.
636 // Otherwise, if can expand, do so.
637 // Otherwise, if using ex regions might help, try with ex given back.
638 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
639 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
640
641 verify_region_sets_optional();
642
643 uint first = G1_NO_HRM_INDEX;
644 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
645
646 if (obj_regions == 1) {
647 // Only one region to allocate, try to use a fast path by directly allocating
648 // from the free lists. Do not try to expand here, we will potentially do that
649 // later.
650 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
651 if (hr != NULL) {
652 first = hr->hrm_index();
653 }
654 } else {
655 // We can't allocate humongous regions spanning more than one region while
656 // cleanupComplete() is running, since some of the regions we find to be
657 // empty might not yet be added to the free list. It is not straightforward
658 // to know in which list they are on so that we can remove them. We only
659 // need to do this if we need to allocate more than one region to satisfy the
660 // current humongous allocation request. If we are only allocating one region
661 // we use the one-region region allocation code (see above), that already
662 // potentially waits for regions from the secondary free list.
663 wait_while_free_regions_coming();
664 append_secondary_free_list_if_not_empty_with_lock();
665
666 // Policy: Try only empty regions (i.e. already committed first). Maybe we
667 // are lucky enough to find some.
668 first = _hrm.find_contiguous_only_empty(obj_regions);
669 if (first != G1_NO_HRM_INDEX) {
670 _hrm.allocate_free_regions_starting_at(first, obj_regions);
671 }
672 }
673
674 if (first == G1_NO_HRM_INDEX) {
675 // Policy: We could not find enough regions for the humongous object in the
676 // free list. Look through the heap to find a mix of free and uncommitted regions.
677 // If so, try expansion.
678 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
679 if (first != G1_NO_HRM_INDEX) {
680 // We found something. Make sure these regions are committed, i.e. expand
681 // the heap. Alternatively we could do a defragmentation GC.
682 ergo_verbose1(ErgoHeapSizing,
683 "attempt heap expansion",
684 ergo_format_reason("humongous allocation request failed")
685 ergo_format_byte("allocation request"),
686 word_size * HeapWordSize);
687
688 _hrm.expand_at(first, obj_regions);
689 g1_policy()->record_new_heap_size(num_regions());
690
691 #ifdef ASSERT
692 for (uint i = first; i < first + obj_regions; ++i) {
693 HeapRegion* hr = region_at(i);
694 assert(hr->is_free(), "sanity");
695 assert(hr->is_empty(), "sanity");
696 assert(is_on_master_free_list(hr), "sanity");
697 }
698 #endif
699 _hrm.allocate_free_regions_starting_at(first, obj_regions);
700 } else {
701 // Policy: Potentially trigger a defragmentation GC.
702 }
703 }
704
705 HeapWord* result = NULL;
706 if (first != G1_NO_HRM_INDEX) {
707 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
708 word_size, context);
709 assert(result != NULL, "it should always return a valid result");
710
711 // A successful humongous object allocation changes the used space
712 // information of the old generation so we need to recalculate the
713 // sizes and update the jstat counters here.
714 g1mm()->update_sizes();
715 }
716
717 verify_region_sets_optional();
718
719 return result;
720 }
721
722 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
723 assert_heap_not_locked_and_not_at_safepoint();
724 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
725
726 uint dummy_gc_count_before;
727 uint dummy_gclocker_retry_count = 0;
728 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
729 }
730
731 HeapWord*
732 G1CollectedHeap::mem_allocate(size_t word_size,
733 bool* gc_overhead_limit_was_exceeded) {
734 assert_heap_not_locked_and_not_at_safepoint();
735
736 // Loop until the allocation is satisfied, or unsatisfied after GC.
737 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
738 uint gc_count_before;
739
740 HeapWord* result = NULL;
741 if (!is_humongous(word_size)) {
742 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
743 } else {
744 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
745 }
746 if (result != NULL) {
747 return result;
748 }
749
750 // Create the garbage collection operation...
751 VM_G1CollectForAllocation op(gc_count_before, word_size);
752 op.set_allocation_context(AllocationContext::current());
753
754 // ...and get the VM thread to execute it.
755 VMThread::execute(&op);
756
757 if (op.prologue_succeeded() && op.pause_succeeded()) {
758 // If the operation was successful we'll return the result even
759 // if it is NULL. If the allocation attempt failed immediately
760 // after a Full GC, it's unlikely we'll be able to allocate now.
761 HeapWord* result = op.result();
762 if (result != NULL && !is_humongous(word_size)) {
763 // Allocations that take place on VM operations do not do any
764 // card dirtying and we have to do it here. We only have to do
765 // this for non-humongous allocations, though.
766 dirty_young_block(result, word_size);
767 }
768 return result;
769 } else {
770 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
771 return NULL;
772 }
773 assert(op.result() == NULL,
774 "the result should be NULL if the VM op did not succeed");
775 }
776
777 // Give a warning if we seem to be looping forever.
778 if ((QueuedAllocationWarningCount > 0) &&
779 (try_count % QueuedAllocationWarningCount == 0)) {
780 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
781 }
782 }
783
784 ShouldNotReachHere();
785 return NULL;
786 }
787
788 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
789 AllocationContext_t context,
790 uint* gc_count_before_ret,
791 uint* gclocker_retry_count_ret) {
792 // Make sure you read the note in attempt_allocation_humongous().
793
794 assert_heap_not_locked_and_not_at_safepoint();
795 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
796 "be called for humongous allocation requests");
797
798 // We should only get here after the first-level allocation attempt
799 // (attempt_allocation()) failed to allocate.
800
801 // We will loop until a) we manage to successfully perform the
802 // allocation or b) we successfully schedule a collection which
803 // fails to perform the allocation. b) is the only case when we'll
804 // return NULL.
805 HeapWord* result = NULL;
806 for (int try_count = 1; /* we'll return */; try_count += 1) {
807 bool should_try_gc;
808 uint gc_count_before;
809
810 {
811 MutexLockerEx x(Heap_lock);
812 result = _allocator->attempt_allocation_locked(word_size, context);
813 if (result != NULL) {
814 return result;
815 }
816
817 if (GC_locker::is_active_and_needs_gc()) {
818 if (g1_policy()->can_expand_young_list()) {
819 // No need for an ergo verbose message here,
820 // can_expand_young_list() does this when it returns true.
821 result = _allocator->attempt_allocation_force(word_size, context);
822 if (result != NULL) {
823 return result;
824 }
825 }
826 should_try_gc = false;
827 } else {
828 // The GCLocker may not be active but the GCLocker initiated
829 // GC may not yet have been performed (GCLocker::needs_gc()
830 // returns true). In this case we do not try this GC and
831 // wait until the GCLocker initiated GC is performed, and
832 // then retry the allocation.
833 if (GC_locker::needs_gc()) {
834 should_try_gc = false;
835 } else {
836 // Read the GC count while still holding the Heap_lock.
837 gc_count_before = total_collections();
838 should_try_gc = true;
839 }
840 }
841 }
842
843 if (should_try_gc) {
844 bool succeeded;
845 result = do_collection_pause(word_size, gc_count_before, &succeeded,
846 GCCause::_g1_inc_collection_pause);
847 if (result != NULL) {
848 assert(succeeded, "only way to get back a non-NULL result");
849 return result;
850 }
851
852 if (succeeded) {
853 // If we get here we successfully scheduled a collection which
854 // failed to allocate. No point in trying to allocate
855 // further. We'll just return NULL.
856 MutexLockerEx x(Heap_lock);
857 *gc_count_before_ret = total_collections();
858 return NULL;
859 }
860 } else {
861 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
862 MutexLockerEx x(Heap_lock);
863 *gc_count_before_ret = total_collections();
864 return NULL;
865 }
866 // The GCLocker is either active or the GCLocker initiated
867 // GC has not yet been performed. Stall until it is and
868 // then retry the allocation.
869 GC_locker::stall_until_clear();
870 (*gclocker_retry_count_ret) += 1;
871 }
872
873 // We can reach here if we were unsuccessful in scheduling a
874 // collection (because another thread beat us to it) or if we were
875 // stalled due to the GC locker. In either can we should retry the
876 // allocation attempt in case another thread successfully
877 // performed a collection and reclaimed enough space. We do the
878 // first attempt (without holding the Heap_lock) here and the
879 // follow-on attempt will be at the start of the next loop
880 // iteration (after taking the Heap_lock).
881 result = _allocator->attempt_allocation(word_size, context);
882 if (result != NULL) {
883 return result;
884 }
885
886 // Give a warning if we seem to be looping forever.
887 if ((QueuedAllocationWarningCount > 0) &&
888 (try_count % QueuedAllocationWarningCount == 0)) {
889 warning("G1CollectedHeap::attempt_allocation_slow() "
890 "retries %d times", try_count);
891 }
892 }
893
894 ShouldNotReachHere();
895 return NULL;
896 }
897
898 void G1CollectedHeap::begin_archive_alloc_range() {
899 assert_at_safepoint(true /* should_be_vm_thread */);
900 if (_archive_allocator == NULL) {
901 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
902 }
903 }
904
905 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
906 // Allocations in archive regions cannot be of a size that would be considered
907 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
908 // may be different at archive-restore time.
909 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
910 }
911
912 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
913 assert_at_safepoint(true /* should_be_vm_thread */);
914 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
915 if (is_archive_alloc_too_large(word_size)) {
916 return NULL;
917 }
918 return _archive_allocator->archive_mem_allocate(word_size);
919 }
920
921 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
922 size_t end_alignment_in_bytes) {
923 assert_at_safepoint(true /* should_be_vm_thread */);
924 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
925
926 // Call complete_archive to do the real work, filling in the MemRegion
927 // array with the archive regions.
928 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
929 delete _archive_allocator;
930 _archive_allocator = NULL;
931 }
932
933 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
934 assert(ranges != NULL, "MemRegion array NULL");
935 assert(count != 0, "No MemRegions provided");
936 MemRegion reserved = _hrm.reserved();
937 for (size_t i = 0; i < count; i++) {
938 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
939 return false;
940 }
941 }
942 return true;
943 }
944
945 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
946 assert(!is_init_completed(), "Expect to be called at JVM init time");
947 assert(ranges != NULL, "MemRegion array NULL");
948 assert(count != 0, "No MemRegions provided");
949 MutexLockerEx x(Heap_lock);
950
951 MemRegion reserved = _hrm.reserved();
952 HeapWord* prev_last_addr = NULL;
953 HeapRegion* prev_last_region = NULL;
954
955 // Temporarily disable pretouching of heap pages. This interface is used
956 // when mmap'ing archived heap data in, so pre-touching is wasted.
957 FlagSetting fs(AlwaysPreTouch, false);
958
959 // Enable archive object checking in G1MarkSweep. We have to let it know
960 // about each archive range, so that objects in those ranges aren't marked.
961 G1MarkSweep::enable_archive_object_check();
962
963 // For each specified MemRegion range, allocate the corresponding G1
964 // regions and mark them as archive regions. We expect the ranges in
965 // ascending starting address order, without overlap.
966 for (size_t i = 0; i < count; i++) {
967 MemRegion curr_range = ranges[i];
968 HeapWord* start_address = curr_range.start();
969 size_t word_size = curr_range.word_size();
970 HeapWord* last_address = curr_range.last();
971 size_t commits = 0;
972
973 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
974 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
975 p2i(start_address), p2i(last_address)));
976 guarantee(start_address > prev_last_addr,
977 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
978 p2i(start_address), p2i(prev_last_addr)));
979 prev_last_addr = last_address;
980
981 // Check for ranges that start in the same G1 region in which the previous
982 // range ended, and adjust the start address so we don't try to allocate
983 // the same region again. If the current range is entirely within that
984 // region, skip it, just adjusting the recorded top.
985 HeapRegion* start_region = _hrm.addr_to_region(start_address);
986 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
987 start_address = start_region->end();
988 if (start_address > last_address) {
989 increase_used(word_size * HeapWordSize);
990 start_region->set_top(last_address + 1);
991 continue;
992 }
993 start_region->set_top(start_address);
994 curr_range = MemRegion(start_address, last_address + 1);
995 start_region = _hrm.addr_to_region(start_address);
996 }
997
998 // Perform the actual region allocation, exiting if it fails.
999 // Then note how much new space we have allocated.
1000 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1001 return false;
1002 }
1003 increase_used(word_size * HeapWordSize);
1004 if (commits != 0) {
1005 ergo_verbose1(ErgoHeapSizing,
1006 "attempt heap expansion",
1007 ergo_format_reason("allocate archive regions")
1008 ergo_format_byte("total size"),
1009 HeapRegion::GrainWords * HeapWordSize * commits);
1010 }
1011
1012 // Mark each G1 region touched by the range as archive, add it to the old set,
1013 // and set the allocation context and top.
1014 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1015 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1016 prev_last_region = last_region;
1017
1018 while (curr_region != NULL) {
1019 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1020 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1021 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1022 curr_region->set_allocation_context(AllocationContext::system());
1023 curr_region->set_archive();
1024 _old_set.add(curr_region);
1025 if (curr_region != last_region) {
1026 curr_region->set_top(curr_region->end());
1027 curr_region = _hrm.next_region_in_heap(curr_region);
1028 } else {
1029 curr_region->set_top(last_address + 1);
1030 curr_region = NULL;
1031 }
1032 }
1033
1034 // Notify mark-sweep of the archive range.
1035 G1MarkSweep::set_range_archive(curr_range, true);
1036 }
1037 return true;
1038 }
1039
1040 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1041 assert(!is_init_completed(), "Expect to be called at JVM init time");
1042 assert(ranges != NULL, "MemRegion array NULL");
1043 assert(count != 0, "No MemRegions provided");
1044 MemRegion reserved = _hrm.reserved();
1045 HeapWord *prev_last_addr = NULL;
1046 HeapRegion* prev_last_region = NULL;
1047
1048 // For each MemRegion, create filler objects, if needed, in the G1 regions
1049 // that contain the address range. The address range actually within the
1050 // MemRegion will not be modified. That is assumed to have been initialized
1051 // elsewhere, probably via an mmap of archived heap data.
1052 MutexLockerEx x(Heap_lock);
1053 for (size_t i = 0; i < count; i++) {
1054 HeapWord* start_address = ranges[i].start();
1055 HeapWord* last_address = ranges[i].last();
1056
1057 assert(reserved.contains(start_address) && reserved.contains(last_address),
1058 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1059 p2i(start_address), p2i(last_address)));
1060 assert(start_address > prev_last_addr,
1061 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1062 p2i(start_address), p2i(prev_last_addr)));
1063
1064 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1065 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1066 HeapWord* bottom_address = start_region->bottom();
1067
1068 // Check for a range beginning in the same region in which the
1069 // previous one ended.
1070 if (start_region == prev_last_region) {
1071 bottom_address = prev_last_addr + 1;
1072 }
1073
1074 // Verify that the regions were all marked as archive regions by
1075 // alloc_archive_regions.
1076 HeapRegion* curr_region = start_region;
1077 while (curr_region != NULL) {
1078 guarantee(curr_region->is_archive(),
1079 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1080 if (curr_region != last_region) {
1081 curr_region = _hrm.next_region_in_heap(curr_region);
1082 } else {
1083 curr_region = NULL;
1084 }
1085 }
1086
1087 prev_last_addr = last_address;
1088 prev_last_region = last_region;
1089
1090 // Fill the memory below the allocated range with dummy object(s),
1091 // if the region bottom does not match the range start, or if the previous
1092 // range ended within the same G1 region, and there is a gap.
1093 if (start_address != bottom_address) {
1094 size_t fill_size = pointer_delta(start_address, bottom_address);
1095 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1096 increase_used(fill_size * HeapWordSize);
1097 }
1098 }
1099 }
1100
1101 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1102 uint* gc_count_before_ret,
1103 uint* gclocker_retry_count_ret) {
1104 assert_heap_not_locked_and_not_at_safepoint();
1105 assert(!is_humongous(word_size), "attempt_allocation() should not "
1106 "be called for humongous allocation requests");
1107
1108 AllocationContext_t context = AllocationContext::current();
1109 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1110
1111 if (result == NULL) {
1112 result = attempt_allocation_slow(word_size,
1113 context,
1114 gc_count_before_ret,
1115 gclocker_retry_count_ret);
1116 }
1117 assert_heap_not_locked();
1118 if (result != NULL) {
1119 dirty_young_block(result, word_size);
1120 }
1121 return result;
1122 }
1123
1124 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
1125 assert(!is_init_completed(), "Expect to be called at JVM init time");
1126 assert(ranges != NULL, "MemRegion array NULL");
1127 assert(count != 0, "No MemRegions provided");
1128 MemRegion reserved = _hrm.reserved();
1129 HeapWord* prev_last_addr = NULL;
1130 HeapRegion* prev_last_region = NULL;
1131 size_t size_used = 0;
1132 size_t uncommitted_regions = 0;
1133
1134 // For each Memregion, free the G1 regions that constitute it, and
1135 // notify mark-sweep that the range is no longer to be considered 'archive.'
1136 MutexLockerEx x(Heap_lock);
1137 for (size_t i = 0; i < count; i++) {
1138 HeapWord* start_address = ranges[i].start();
1139 HeapWord* last_address = ranges[i].last();
1140
1141 assert(reserved.contains(start_address) && reserved.contains(last_address),
1142 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1143 p2i(start_address), p2i(last_address)));
1144 assert(start_address > prev_last_addr,
1145 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1146 p2i(start_address), p2i(prev_last_addr)));
1147 size_used += ranges[i].byte_size();
1148 prev_last_addr = last_address;
1149
1150 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1151 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1152
1153 // Check for ranges that start in the same G1 region in which the previous
1154 // range ended, and adjust the start address so we don't try to free
1155 // the same region again. If the current range is entirely within that
1156 // region, skip it.
1157 if (start_region == prev_last_region) {
1158 start_address = start_region->end();
1159 if (start_address > last_address) {
1160 continue;
1161 }
1162 start_region = _hrm.addr_to_region(start_address);
1163 }
1164 prev_last_region = last_region;
1165
1166 // After verifying that each region was marked as an archive region by
1167 // alloc_archive_regions, set it free and empty and uncommit it.
1168 HeapRegion* curr_region = start_region;
1169 while (curr_region != NULL) {
1170 guarantee(curr_region->is_archive(),
1171 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1172 uint curr_index = curr_region->hrm_index();
1173 _old_set.remove(curr_region);
1174 curr_region->set_free();
1175 curr_region->set_top(curr_region->bottom());
1176 if (curr_region != last_region) {
1177 curr_region = _hrm.next_region_in_heap(curr_region);
1178 } else {
1179 curr_region = NULL;
1180 }
1181 _hrm.shrink_at(curr_index, 1);
1182 uncommitted_regions++;
1183 }
1184
1185 // Notify mark-sweep that this is no longer an archive range.
1186 G1MarkSweep::set_range_archive(ranges[i], false);
1187 }
1188
1189 if (uncommitted_regions != 0) {
1190 ergo_verbose1(ErgoHeapSizing,
1191 "attempt heap shrinking",
1192 ergo_format_reason("uncommitted archive regions")
1193 ergo_format_byte("total size"),
1194 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1195 }
1196 decrease_used(size_used);
1197 }
1198
1199 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1200 uint* gc_count_before_ret,
1201 uint* gclocker_retry_count_ret) {
1202 // The structure of this method has a lot of similarities to
1203 // attempt_allocation_slow(). The reason these two were not merged
1204 // into a single one is that such a method would require several "if
1205 // allocation is not humongous do this, otherwise do that"
1206 // conditional paths which would obscure its flow. In fact, an early
1207 // version of this code did use a unified method which was harder to
1208 // follow and, as a result, it had subtle bugs that were hard to
1209 // track down. So keeping these two methods separate allows each to
1210 // be more readable. It will be good to keep these two in sync as
1211 // much as possible.
1212
1213 assert_heap_not_locked_and_not_at_safepoint();
1214 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1215 "should only be called for humongous allocations");
1216
1217 // Humongous objects can exhaust the heap quickly, so we should check if we
1218 // need to start a marking cycle at each humongous object allocation. We do
1219 // the check before we do the actual allocation. The reason for doing it
1220 // before the allocation is that we avoid having to keep track of the newly
1221 // allocated memory while we do a GC.
1222 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1223 word_size)) {
1224 collect(GCCause::_g1_humongous_allocation);
1225 }
1226
1227 // We will loop until a) we manage to successfully perform the
1228 // allocation or b) we successfully schedule a collection which
1229 // fails to perform the allocation. b) is the only case when we'll
1230 // return NULL.
1231 HeapWord* result = NULL;
1232 for (int try_count = 1; /* we'll return */; try_count += 1) {
1233 bool should_try_gc;
1234 uint gc_count_before;
1235
1236 {
1237 MutexLockerEx x(Heap_lock);
1238
1239 // Given that humongous objects are not allocated in young
1240 // regions, we'll first try to do the allocation without doing a
1241 // collection hoping that there's enough space in the heap.
1242 result = humongous_obj_allocate(word_size, AllocationContext::current());
1243 if (result != NULL) {
1244 return result;
1245 }
1246
1247 if (GC_locker::is_active_and_needs_gc()) {
1248 should_try_gc = false;
1249 } else {
1250 // The GCLocker may not be active but the GCLocker initiated
1251 // GC may not yet have been performed (GCLocker::needs_gc()
1252 // returns true). In this case we do not try this GC and
1253 // wait until the GCLocker initiated GC is performed, and
1254 // then retry the allocation.
1255 if (GC_locker::needs_gc()) {
1256 should_try_gc = false;
1257 } else {
1258 // Read the GC count while still holding the Heap_lock.
1259 gc_count_before = total_collections();
1260 should_try_gc = true;
1261 }
1262 }
1263 }
1264
1265 if (should_try_gc) {
1266 // If we failed to allocate the humongous object, we should try to
1267 // do a collection pause (if we're allowed) in case it reclaims
1268 // enough space for the allocation to succeed after the pause.
1269
1270 bool succeeded;
1271 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1272 GCCause::_g1_humongous_allocation);
1273 if (result != NULL) {
1274 assert(succeeded, "only way to get back a non-NULL result");
1275 return result;
1276 }
1277
1278 if (succeeded) {
1279 // If we get here we successfully scheduled a collection which
1280 // failed to allocate. No point in trying to allocate
1281 // further. We'll just return NULL.
1282 MutexLockerEx x(Heap_lock);
1283 *gc_count_before_ret = total_collections();
1284 return NULL;
1285 }
1286 } else {
1287 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1288 MutexLockerEx x(Heap_lock);
1289 *gc_count_before_ret = total_collections();
1290 return NULL;
1291 }
1292 // The GCLocker is either active or the GCLocker initiated
1293 // GC has not yet been performed. Stall until it is and
1294 // then retry the allocation.
1295 GC_locker::stall_until_clear();
1296 (*gclocker_retry_count_ret) += 1;
1297 }
1298
1299 // We can reach here if we were unsuccessful in scheduling a
1300 // collection (because another thread beat us to it) or if we were
1301 // stalled due to the GC locker. In either can we should retry the
1302 // allocation attempt in case another thread successfully
1303 // performed a collection and reclaimed enough space. Give a
1304 // warning if we seem to be looping forever.
1305
1306 if ((QueuedAllocationWarningCount > 0) &&
1307 (try_count % QueuedAllocationWarningCount == 0)) {
1308 warning("G1CollectedHeap::attempt_allocation_humongous() "
1309 "retries %d times", try_count);
1310 }
1311 }
1312
1313 ShouldNotReachHere();
1314 return NULL;
1315 }
1316
1317 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1318 AllocationContext_t context,
1319 bool expect_null_mutator_alloc_region) {
1320 assert_at_safepoint(true /* should_be_vm_thread */);
1321 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1322 "the current alloc region was unexpectedly found to be non-NULL");
1323
1324 if (!is_humongous(word_size)) {
1325 return _allocator->attempt_allocation_locked(word_size, context);
1326 } else {
1327 HeapWord* result = humongous_obj_allocate(word_size, context);
1328 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1329 collector_state()->set_initiate_conc_mark_if_possible(true);
1330 }
1331 return result;
1332 }
1333
1334 ShouldNotReachHere();
1335 }
1336
1337 class PostMCRemSetClearClosure: public HeapRegionClosure {
1338 G1CollectedHeap* _g1h;
1339 ModRefBarrierSet* _mr_bs;
1340 public:
1341 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1342 _g1h(g1h), _mr_bs(mr_bs) {}
1343
1344 bool doHeapRegion(HeapRegion* r) {
1345 HeapRegionRemSet* hrrs = r->rem_set();
1346
1347 if (r->is_continues_humongous()) {
1348 // We'll assert that the strong code root list and RSet is empty
1349 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1350 assert(hrrs->occupied() == 0, "RSet should be empty");
1351 return false;
1352 }
1353
1354 _g1h->reset_gc_time_stamps(r);
1355 hrrs->clear();
1356 // You might think here that we could clear just the cards
1357 // corresponding to the used region. But no: if we leave a dirty card
1358 // in a region we might allocate into, then it would prevent that card
1359 // from being enqueued, and cause it to be missed.
1360 // Re: the performance cost: we shouldn't be doing full GC anyway!
1361 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1362
1363 return false;
1364 }
1365 };
1366
1367 void G1CollectedHeap::clear_rsets_post_compaction() {
1368 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1369 heap_region_iterate(&rs_clear);
1370 }
1371
1372 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1373 G1CollectedHeap* _g1h;
1374 UpdateRSOopClosure _cl;
1375 public:
1376 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1377 _cl(g1->g1_rem_set(), worker_i),
1378 _g1h(g1)
1379 { }
1380
1381 bool doHeapRegion(HeapRegion* r) {
1382 if (!r->is_continues_humongous()) {
1383 _cl.set_from(r);
1384 r->oop_iterate(&_cl);
1385 }
1386 return false;
1387 }
1388 };
1389
1390 class ParRebuildRSTask: public AbstractGangTask {
1391 G1CollectedHeap* _g1;
1392 HeapRegionClaimer _hrclaimer;
1393
1394 public:
1395 ParRebuildRSTask(G1CollectedHeap* g1) :
1396 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1397
1398 void work(uint worker_id) {
1399 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1400 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1401 }
1402 };
1403
1404 class PostCompactionPrinterClosure: public HeapRegionClosure {
1405 private:
1406 G1HRPrinter* _hr_printer;
1407 public:
1408 bool doHeapRegion(HeapRegion* hr) {
1409 assert(!hr->is_young(), "not expecting to find young regions");
1410 if (hr->is_free()) {
1411 // We only generate output for non-empty regions.
1412 } else if (hr->is_starts_humongous()) {
1413 if (hr->region_num() == 1) {
1414 // single humongous region
1415 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1416 } else {
1417 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1418 }
1419 } else if (hr->is_continues_humongous()) {
1420 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1421 } else if (hr->is_archive()) {
1422 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1423 } else if (hr->is_old()) {
1424 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1425 } else {
1426 ShouldNotReachHere();
1427 }
1428 return false;
1429 }
1430
1431 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1432 : _hr_printer(hr_printer) { }
1433 };
1434
1435 void G1CollectedHeap::print_hrm_post_compaction() {
1436 PostCompactionPrinterClosure cl(hr_printer());
1437 heap_region_iterate(&cl);
1438 }
1439
1440 bool G1CollectedHeap::do_collection(bool explicit_gc,
1441 bool clear_all_soft_refs,
1442 size_t word_size) {
1443 assert_at_safepoint(true /* should_be_vm_thread */);
1444
1445 if (GC_locker::check_active_before_gc()) {
1446 return false;
1447 }
1448
1449 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1450 gc_timer->register_gc_start();
1451
1452 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1453 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1454
1455 SvcGCMarker sgcm(SvcGCMarker::FULL);
1456 ResourceMark rm;
1457
1458 G1Log::update_level();
1459 print_heap_before_gc();
1460 trace_heap_before_gc(gc_tracer);
1461
1462 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1463
1464 verify_region_sets_optional();
1465
1466 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1467 collector_policy()->should_clear_all_soft_refs();
1468
1469 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1470
1471 {
1472 IsGCActiveMark x;
1473
1474 // Timing
1475 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1476 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1477
1478 {
1479 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1480 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1481 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1482
1483 g1_policy()->record_full_collection_start();
1484
1485 // Note: When we have a more flexible GC logging framework that
1486 // allows us to add optional attributes to a GC log record we
1487 // could consider timing and reporting how long we wait in the
1488 // following two methods.
1489 wait_while_free_regions_coming();
1490 // If we start the compaction before the CM threads finish
1491 // scanning the root regions we might trip them over as we'll
1492 // be moving objects / updating references. So let's wait until
1493 // they are done. By telling them to abort, they should complete
1494 // early.
1495 _cm->root_regions()->abort();
1496 _cm->root_regions()->wait_until_scan_finished();
1497 append_secondary_free_list_if_not_empty_with_lock();
1498
1499 gc_prologue(true);
1500 increment_total_collections(true /* full gc */);
1501 increment_old_marking_cycles_started();
1502
1503 assert(used() == recalculate_used(), "Should be equal");
1504
1505 verify_before_gc();
1506
1507 check_bitmaps("Full GC Start");
1508 pre_full_gc_dump(gc_timer);
1509
1510 #if defined(COMPILER2) || INCLUDE_JVMCI
1511 DerivedPointerTable::clear();
1512 #endif
1513
1514 // Disable discovery and empty the discovered lists
1515 // for the CM ref processor.
1516 ref_processor_cm()->disable_discovery();
1517 ref_processor_cm()->abandon_partial_discovery();
1518 ref_processor_cm()->verify_no_references_recorded();
1519
1520 // Abandon current iterations of concurrent marking and concurrent
1521 // refinement, if any are in progress. We have to do this before
1522 // wait_until_scan_finished() below.
1523 concurrent_mark()->abort();
1524
1525 // Make sure we'll choose a new allocation region afterwards.
1526 _allocator->release_mutator_alloc_region();
1527 _allocator->abandon_gc_alloc_regions();
1528 g1_rem_set()->cleanupHRRS();
1529
1530 // We should call this after we retire any currently active alloc
1531 // regions so that all the ALLOC / RETIRE events are generated
1532 // before the start GC event.
1533 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1534
1535 // We may have added regions to the current incremental collection
1536 // set between the last GC or pause and now. We need to clear the
1537 // incremental collection set and then start rebuilding it afresh
1538 // after this full GC.
1539 abandon_collection_set(g1_policy()->inc_cset_head());
1540 g1_policy()->clear_incremental_cset();
1541 g1_policy()->stop_incremental_cset_building();
1542
1543 tear_down_region_sets(false /* free_list_only */);
1544 collector_state()->set_gcs_are_young(true);
1545
1546 // See the comments in g1CollectedHeap.hpp and
1547 // G1CollectedHeap::ref_processing_init() about
1548 // how reference processing currently works in G1.
1549
1550 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1551 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1552
1553 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1554 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1555
1556 ref_processor_stw()->enable_discovery();
1557 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1558
1559 // Do collection work
1560 {
1561 HandleMark hm; // Discard invalid handles created during gc
1562 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1563 }
1564
1565 assert(num_free_regions() == 0, "we should not have added any free regions");
1566 rebuild_region_sets(false /* free_list_only */);
1567
1568 // Enqueue any discovered reference objects that have
1569 // not been removed from the discovered lists.
1570 ref_processor_stw()->enqueue_discovered_references();
1571
1572 #if defined(COMPILER2) || INCLUDE_JVMCI
1573 DerivedPointerTable::update_pointers();
1574 #endif
1575
1576 MemoryService::track_memory_usage();
1577
1578 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1579 ref_processor_stw()->verify_no_references_recorded();
1580
1581 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1582 ClassLoaderDataGraph::purge();
1583 MetaspaceAux::verify_metrics();
1584
1585 // Note: since we've just done a full GC, concurrent
1586 // marking is no longer active. Therefore we need not
1587 // re-enable reference discovery for the CM ref processor.
1588 // That will be done at the start of the next marking cycle.
1589 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1590 ref_processor_cm()->verify_no_references_recorded();
1591
1592 reset_gc_time_stamp();
1593 // Since everything potentially moved, we will clear all remembered
1594 // sets, and clear all cards. Later we will rebuild remembered
1595 // sets. We will also reset the GC time stamps of the regions.
1596 clear_rsets_post_compaction();
1597 check_gc_time_stamps();
1598
1599 // Resize the heap if necessary.
1600 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1601
1602 if (_hr_printer.is_active()) {
1603 // We should do this after we potentially resize the heap so
1604 // that all the COMMIT / UNCOMMIT events are generated before
1605 // the end GC event.
1606
1607 print_hrm_post_compaction();
1608 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1609 }
1610
1611 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1612 if (hot_card_cache->use_cache()) {
1613 hot_card_cache->reset_card_counts();
1614 hot_card_cache->reset_hot_cache();
1615 }
1616
1617 // Rebuild remembered sets of all regions.
1618 uint n_workers =
1619 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1620 workers()->active_workers(),
1621 Threads::number_of_non_daemon_threads());
1622 workers()->set_active_workers(n_workers);
1623
1624 ParRebuildRSTask rebuild_rs_task(this);
1625 workers()->run_task(&rebuild_rs_task);
1626
1627 // Rebuild the strong code root lists for each region
1628 rebuild_strong_code_roots();
1629
1630 if (true) { // FIXME
1631 MetaspaceGC::compute_new_size();
1632 }
1633
1634 #ifdef TRACESPINNING
1635 ParallelTaskTerminator::print_termination_counts();
1636 #endif
1637
1638 // Discard all rset updates
1639 JavaThread::dirty_card_queue_set().abandon_logs();
1640 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1641
1642 _young_list->reset_sampled_info();
1643 // At this point there should be no regions in the
1644 // entire heap tagged as young.
1645 assert(check_young_list_empty(true /* check_heap */),
1646 "young list should be empty at this point");
1647
1648 // Update the number of full collections that have been completed.
1649 increment_old_marking_cycles_completed(false /* concurrent */);
1650
1651 _hrm.verify_optional();
1652 verify_region_sets_optional();
1653
1654 verify_after_gc();
1655
1656 // Clear the previous marking bitmap, if needed for bitmap verification.
1657 // Note we cannot do this when we clear the next marking bitmap in
1658 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1659 // objects marked during a full GC against the previous bitmap.
1660 // But we need to clear it before calling check_bitmaps below since
1661 // the full GC has compacted objects and updated TAMS but not updated
1662 // the prev bitmap.
1663 if (G1VerifyBitmaps) {
1664 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1665 }
1666 check_bitmaps("Full GC End");
1667
1668 // Start a new incremental collection set for the next pause
1669 assert(g1_policy()->collection_set() == NULL, "must be");
1670 g1_policy()->start_incremental_cset_building();
1671
1672 clear_cset_fast_test();
1673
1674 _allocator->init_mutator_alloc_region();
1675
1676 g1_policy()->record_full_collection_end();
1677
1678 if (G1Log::fine()) {
1679 g1_policy()->print_heap_transition();
1680 }
1681
1682 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1683 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1684 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1685 // before any GC notifications are raised.
1686 g1mm()->update_sizes();
1687
1688 gc_epilogue(true);
1689 }
1690
1691 if (G1Log::finer()) {
1692 g1_policy()->print_detailed_heap_transition(true /* full */);
1693 }
1694
1695 print_heap_after_gc();
1696 trace_heap_after_gc(gc_tracer);
1697
1698 post_full_gc_dump(gc_timer);
1699
1700 gc_timer->register_gc_end();
1701 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1702 }
1703
1704 return true;
1705 }
1706
1707 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1708 // do_collection() will return whether it succeeded in performing
1709 // the GC. Currently, there is no facility on the
1710 // do_full_collection() API to notify the caller than the collection
1711 // did not succeed (e.g., because it was locked out by the GC
1712 // locker). So, right now, we'll ignore the return value.
1713 bool dummy = do_collection(true, /* explicit_gc */
1714 clear_all_soft_refs,
1715 0 /* word_size */);
1716 }
1717
1718 // This code is mostly copied from TenuredGeneration.
1719 void
1720 G1CollectedHeap::
1721 resize_if_necessary_after_full_collection(size_t word_size) {
1722 // Include the current allocation, if any, and bytes that will be
1723 // pre-allocated to support collections, as "used".
1724 const size_t used_after_gc = used();
1725 const size_t capacity_after_gc = capacity();
1726 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1727
1728 // This is enforced in arguments.cpp.
1729 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1730 "otherwise the code below doesn't make sense");
1731
1732 // We don't have floating point command-line arguments
1733 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1734 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1735 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1736 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1737
1738 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1739 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1740
1741 // We have to be careful here as these two calculations can overflow
1742 // 32-bit size_t's.
1743 double used_after_gc_d = (double) used_after_gc;
1744 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1745 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1746
1747 // Let's make sure that they are both under the max heap size, which
1748 // by default will make them fit into a size_t.
1749 double desired_capacity_upper_bound = (double) max_heap_size;
1750 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1751 desired_capacity_upper_bound);
1752 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1753 desired_capacity_upper_bound);
1754
1755 // We can now safely turn them into size_t's.
1756 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1757 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1758
1759 // This assert only makes sense here, before we adjust them
1760 // with respect to the min and max heap size.
1761 assert(minimum_desired_capacity <= maximum_desired_capacity,
1762 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1763 "maximum_desired_capacity = " SIZE_FORMAT,
1764 minimum_desired_capacity, maximum_desired_capacity));
1765
1766 // Should not be greater than the heap max size. No need to adjust
1767 // it with respect to the heap min size as it's a lower bound (i.e.,
1768 // we'll try to make the capacity larger than it, not smaller).
1769 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1770 // Should not be less than the heap min size. No need to adjust it
1771 // with respect to the heap max size as it's an upper bound (i.e.,
1772 // we'll try to make the capacity smaller than it, not greater).
1773 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1774
1775 if (capacity_after_gc < minimum_desired_capacity) {
1776 // Don't expand unless it's significant
1777 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1778 ergo_verbose4(ErgoHeapSizing,
1779 "attempt heap expansion",
1780 ergo_format_reason("capacity lower than "
1781 "min desired capacity after Full GC")
1782 ergo_format_byte("capacity")
1783 ergo_format_byte("occupancy")
1784 ergo_format_byte_perc("min desired capacity"),
1785 capacity_after_gc, used_after_gc,
1786 minimum_desired_capacity, (double) MinHeapFreeRatio);
1787 expand(expand_bytes);
1788
1789 // No expansion, now see if we want to shrink
1790 } else if (capacity_after_gc > maximum_desired_capacity) {
1791 // Capacity too large, compute shrinking size
1792 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1793 ergo_verbose4(ErgoHeapSizing,
1794 "attempt heap shrinking",
1795 ergo_format_reason("capacity higher than "
1796 "max desired capacity after Full GC")
1797 ergo_format_byte("capacity")
1798 ergo_format_byte("occupancy")
1799 ergo_format_byte_perc("max desired capacity"),
1800 capacity_after_gc, used_after_gc,
1801 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1802 shrink(shrink_bytes);
1803 }
1804 }
1805
1806
1807 HeapWord*
1808 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1809 AllocationContext_t context,
1810 bool* succeeded) {
1811 assert_at_safepoint(true /* should_be_vm_thread */);
1812
1813 *succeeded = true;
1814 // Let's attempt the allocation first.
1815 HeapWord* result =
1816 attempt_allocation_at_safepoint(word_size,
1817 context,
1818 false /* expect_null_mutator_alloc_region */);
1819 if (result != NULL) {
1820 assert(*succeeded, "sanity");
1821 return result;
1822 }
1823
1824 // In a G1 heap, we're supposed to keep allocation from failing by
1825 // incremental pauses. Therefore, at least for now, we'll favor
1826 // expansion over collection. (This might change in the future if we can
1827 // do something smarter than full collection to satisfy a failed alloc.)
1828 result = expand_and_allocate(word_size, context);
1829 if (result != NULL) {
1830 assert(*succeeded, "sanity");
1831 return result;
1832 }
1833
1834 // Expansion didn't work, we'll try to do a Full GC.
1835 bool gc_succeeded = do_collection(false, /* explicit_gc */
1836 false, /* clear_all_soft_refs */
1837 word_size);
1838 if (!gc_succeeded) {
1839 *succeeded = false;
1840 return NULL;
1841 }
1842
1843 // Retry the allocation
1844 result = attempt_allocation_at_safepoint(word_size,
1845 context,
1846 true /* expect_null_mutator_alloc_region */);
1847 if (result != NULL) {
1848 assert(*succeeded, "sanity");
1849 return result;
1850 }
1851
1852 // Then, try a Full GC that will collect all soft references.
1853 gc_succeeded = do_collection(false, /* explicit_gc */
1854 true, /* clear_all_soft_refs */
1855 word_size);
1856 if (!gc_succeeded) {
1857 *succeeded = false;
1858 return NULL;
1859 }
1860
1861 // Retry the allocation once more
1862 result = attempt_allocation_at_safepoint(word_size,
1863 context,
1864 true /* expect_null_mutator_alloc_region */);
1865 if (result != NULL) {
1866 assert(*succeeded, "sanity");
1867 return result;
1868 }
1869
1870 assert(!collector_policy()->should_clear_all_soft_refs(),
1871 "Flag should have been handled and cleared prior to this point");
1872
1873 // What else? We might try synchronous finalization later. If the total
1874 // space available is large enough for the allocation, then a more
1875 // complete compaction phase than we've tried so far might be
1876 // appropriate.
1877 assert(*succeeded, "sanity");
1878 return NULL;
1879 }
1880
1881 // Attempting to expand the heap sufficiently
1882 // to support an allocation of the given "word_size". If
1883 // successful, perform the allocation and return the address of the
1884 // allocated block, or else "NULL".
1885
1886 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1887 assert_at_safepoint(true /* should_be_vm_thread */);
1888
1889 verify_region_sets_optional();
1890
1891 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1892 ergo_verbose1(ErgoHeapSizing,
1893 "attempt heap expansion",
1894 ergo_format_reason("allocation request failed")
1895 ergo_format_byte("allocation request"),
1896 word_size * HeapWordSize);
1897 if (expand(expand_bytes)) {
1898 _hrm.verify_optional();
1899 verify_region_sets_optional();
1900 return attempt_allocation_at_safepoint(word_size,
1901 context,
1902 false /* expect_null_mutator_alloc_region */);
1903 }
1904 return NULL;
1905 }
1906
1907 bool G1CollectedHeap::expand(size_t expand_bytes) {
1908 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1909 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1910 HeapRegion::GrainBytes);
1911 ergo_verbose2(ErgoHeapSizing,
1912 "expand the heap",
1913 ergo_format_byte("requested expansion amount")
1914 ergo_format_byte("attempted expansion amount"),
1915 expand_bytes, aligned_expand_bytes);
1916
1917 if (is_maximal_no_gc()) {
1918 ergo_verbose0(ErgoHeapSizing,
1919 "did not expand the heap",
1920 ergo_format_reason("heap already fully expanded"));
1921 return false;
1922 }
1923
1924 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1925 assert(regions_to_expand > 0, "Must expand by at least one region");
1926
1927 uint expanded_by = _hrm.expand_by(regions_to_expand);
1928
1929 if (expanded_by > 0) {
1930 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1931 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1932 g1_policy()->record_new_heap_size(num_regions());
1933 } else {
1934 ergo_verbose0(ErgoHeapSizing,
1935 "did not expand the heap",
1936 ergo_format_reason("heap expansion operation failed"));
1937 // The expansion of the virtual storage space was unsuccessful.
1938 // Let's see if it was because we ran out of swap.
1939 if (G1ExitOnExpansionFailure &&
1940 _hrm.available() >= regions_to_expand) {
1941 // We had head room...
1942 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1943 }
1944 }
1945 return regions_to_expand > 0;
1946 }
1947
1948 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1949 size_t aligned_shrink_bytes =
1950 ReservedSpace::page_align_size_down(shrink_bytes);
1951 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1952 HeapRegion::GrainBytes);
1953 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1954
1955 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1956 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1957
1958 ergo_verbose3(ErgoHeapSizing,
1959 "shrink the heap",
1960 ergo_format_byte("requested shrinking amount")
1961 ergo_format_byte("aligned shrinking amount")
1962 ergo_format_byte("attempted shrinking amount"),
1963 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1964 if (num_regions_removed > 0) {
1965 g1_policy()->record_new_heap_size(num_regions());
1966 } else {
1967 ergo_verbose0(ErgoHeapSizing,
1968 "did not shrink the heap",
1969 ergo_format_reason("heap shrinking operation failed"));
1970 }
1971 }
1972
1973 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1974 verify_region_sets_optional();
1975
1976 // We should only reach here at the end of a Full GC which means we
1977 // should not not be holding to any GC alloc regions. The method
1978 // below will make sure of that and do any remaining clean up.
1979 _allocator->abandon_gc_alloc_regions();
1980
1981 // Instead of tearing down / rebuilding the free lists here, we
1982 // could instead use the remove_all_pending() method on free_list to
1983 // remove only the ones that we need to remove.
1984 tear_down_region_sets(true /* free_list_only */);
1985 shrink_helper(shrink_bytes);
1986 rebuild_region_sets(true /* free_list_only */);
1987
1988 _hrm.verify_optional();
1989 verify_region_sets_optional();
1990 }
1991
1992 // Public methods.
1993
1994 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1995 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1996 #endif // _MSC_VER
1997
1998
1999 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
2000 CollectedHeap(),
2001 _g1_policy(policy_),
2002 _dirty_card_queue_set(false),
2003 _into_cset_dirty_card_queue_set(false),
2004 _is_alive_closure_cm(this),
2005 _is_alive_closure_stw(this),
2006 _ref_processor_cm(NULL),
2007 _ref_processor_stw(NULL),
2008 _bot_shared(NULL),
2009 _cg1r(NULL),
2010 _g1mm(NULL),
2011 _refine_cte_cl(NULL),
2012 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2013 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2014 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2015 _humongous_reclaim_candidates(),
2016 _has_humongous_reclaim_candidates(false),
2017 _archive_allocator(NULL),
2018 _free_regions_coming(false),
2019 _young_list(new YoungList(this)),
2020 _gc_time_stamp(0),
2021 _summary_bytes_used(0),
2022 _survivor_evac_stats(YoungPLABSize, PLABWeight),
2023 _old_evac_stats(OldPLABSize, PLABWeight),
2024 _expand_heap_after_alloc_failure(true),
2025 _old_marking_cycles_started(0),
2026 _old_marking_cycles_completed(0),
2027 _heap_summary_sent(false),
2028 _in_cset_fast_test(),
2029 _dirty_cards_region_list(NULL),
2030 _worker_cset_start_region(NULL),
2031 _worker_cset_start_region_time_stamp(NULL),
2032 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2033 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2034 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2035 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2036
2037 _workers = new WorkGang("GC Thread", ParallelGCThreads,
2038 /* are_GC_task_threads */true,
2039 /* are_ConcurrentGC_threads */false);
2040 _workers->initialize_workers();
2041
2042 _allocator = G1Allocator::create_allocator(this);
2043 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2044
2045 // Override the default _filler_array_max_size so that no humongous filler
2046 // objects are created.
2047 _filler_array_max_size = _humongous_object_threshold_in_words;
2048
2049 uint n_queues = ParallelGCThreads;
2050 _task_queues = new RefToScanQueueSet(n_queues);
2051
2052 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2053 assert(n_rem_sets > 0, "Invariant.");
2054
2055 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2056 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2057 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2058
2059 for (uint i = 0; i < n_queues; i++) {
2060 RefToScanQueue* q = new RefToScanQueue();
2061 q->initialize();
2062 _task_queues->register_queue(i, q);
2063 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2064 }
2065 clear_cset_start_regions();
2066
2067 // Initialize the G1EvacuationFailureALot counters and flags.
2068 NOT_PRODUCT(reset_evacuation_should_fail();)
2069
2070 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2071 }
2072
2073 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2074 size_t size,
2075 size_t translation_factor) {
2076 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2077 // Allocate a new reserved space, preferring to use large pages.
2078 ReservedSpace rs(size, preferred_page_size);
2079 G1RegionToSpaceMapper* result =
2080 G1RegionToSpaceMapper::create_mapper(rs,
2081 size,
2082 rs.alignment(),
2083 HeapRegion::GrainBytes,
2084 translation_factor,
2085 mtGC);
2086 if (TracePageSizes) {
2087 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2088 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2089 }
2090 return result;
2091 }
2092
2093 jint G1CollectedHeap::initialize() {
2094 CollectedHeap::pre_initialize();
2095 os::enable_vtime();
2096
2097 G1Log::init();
2098
2099 // Necessary to satisfy locking discipline assertions.
2100
2101 MutexLocker x(Heap_lock);
2102
2103 // We have to initialize the printer before committing the heap, as
2104 // it will be used then.
2105 _hr_printer.set_active(G1PrintHeapRegions);
2106
2107 // While there are no constraints in the GC code that HeapWordSize
2108 // be any particular value, there are multiple other areas in the
2109 // system which believe this to be true (e.g. oop->object_size in some
2110 // cases incorrectly returns the size in wordSize units rather than
2111 // HeapWordSize).
2112 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2113
2114 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2115 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2116 size_t heap_alignment = collector_policy()->heap_alignment();
2117
2118 // Ensure that the sizes are properly aligned.
2119 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2120 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2121 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2122
2123 _refine_cte_cl = new RefineCardTableEntryClosure();
2124
2125 jint ecode = JNI_OK;
2126 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
2127 if (_cg1r == NULL) {
2128 return ecode;
2129 }
2130
2131 // Reserve the maximum.
2132
2133 // When compressed oops are enabled, the preferred heap base
2134 // is calculated by subtracting the requested size from the
2135 // 32Gb boundary and using the result as the base address for
2136 // heap reservation. If the requested size is not aligned to
2137 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2138 // into the ReservedHeapSpace constructor) then the actual
2139 // base of the reserved heap may end up differing from the
2140 // address that was requested (i.e. the preferred heap base).
2141 // If this happens then we could end up using a non-optimal
2142 // compressed oops mode.
2143
2144 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2145 heap_alignment);
2146
2147 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2148
2149 // Create the barrier set for the entire reserved region.
2150 G1SATBCardTableLoggingModRefBS* bs
2151 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2152 bs->initialize();
2153 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2154 set_barrier_set(bs);
2155
2156 // Also create a G1 rem set.
2157 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2158
2159 // Carve out the G1 part of the heap.
2160
2161 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2162 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2163 G1RegionToSpaceMapper* heap_storage =
2164 G1RegionToSpaceMapper::create_mapper(g1_rs,
2165 g1_rs.size(),
2166 page_size,
2167 HeapRegion::GrainBytes,
2168 1,
2169 mtJavaHeap);
2170 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2171 max_byte_size, page_size,
2172 heap_rs.base(),
2173 heap_rs.size());
2174 heap_storage->set_mapping_changed_listener(&_listener);
2175
2176 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2177 G1RegionToSpaceMapper* bot_storage =
2178 create_aux_memory_mapper("Block offset table",
2179 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2180 G1BlockOffsetSharedArray::heap_map_factor());
2181
2182 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2183 G1RegionToSpaceMapper* cardtable_storage =
2184 create_aux_memory_mapper("Card table",
2185 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2186 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2187
2188 G1RegionToSpaceMapper* card_counts_storage =
2189 create_aux_memory_mapper("Card counts table",
2190 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2191 G1CardCounts::heap_map_factor());
2192
2193 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2194 G1RegionToSpaceMapper* prev_bitmap_storage =
2195 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2196 G1RegionToSpaceMapper* next_bitmap_storage =
2197 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2198
2199 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2200 g1_barrier_set()->initialize(cardtable_storage);
2201 // Do later initialization work for concurrent refinement.
2202 _cg1r->init(card_counts_storage);
2203
2204 // 6843694 - ensure that the maximum region index can fit
2205 // in the remembered set structures.
2206 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2207 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2208
2209 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2210 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2211 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2212 "too many cards per region");
2213
2214 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2215
2216 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2217
2218 {
2219 HeapWord* start = _hrm.reserved().start();
2220 HeapWord* end = _hrm.reserved().end();
2221 size_t granularity = HeapRegion::GrainBytes;
2222
2223 _in_cset_fast_test.initialize(start, end, granularity);
2224 _humongous_reclaim_candidates.initialize(start, end, granularity);
2225 }
2226
2227 // Create the ConcurrentMark data structure and thread.
2228 // (Must do this late, so that "max_regions" is defined.)
2229 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2230 if (_cm == NULL || !_cm->completed_initialization()) {
2231 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2232 return JNI_ENOMEM;
2233 }
2234 _cmThread = _cm->cmThread();
2235
2236 // Initialize the from_card cache structure of HeapRegionRemSet.
2237 HeapRegionRemSet::init_heap(max_regions());
2238
2239 // Now expand into the initial heap size.
2240 if (!expand(init_byte_size)) {
2241 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2242 return JNI_ENOMEM;
2243 }
2244
2245 // Perform any initialization actions delegated to the policy.
2246 g1_policy()->init();
2247
2248 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2249 SATB_Q_FL_lock,
2250 G1SATBProcessCompletedThreshold,
2251 Shared_SATB_Q_lock);
2252
2253 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2254 DirtyCardQ_CBL_mon,
2255 DirtyCardQ_FL_lock,
2256 concurrent_g1_refine()->yellow_zone(),
2257 concurrent_g1_refine()->red_zone(),
2258 Shared_DirtyCardQ_lock);
2259
2260 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2261 DirtyCardQ_CBL_mon,
2262 DirtyCardQ_FL_lock,
2263 -1, // never trigger processing
2264 -1, // no limit on length
2265 Shared_DirtyCardQ_lock,
2266 &JavaThread::dirty_card_queue_set());
2267
2268 // Initialize the card queue set used to hold cards containing
2269 // references into the collection set.
2270 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2271 DirtyCardQ_CBL_mon,
2272 DirtyCardQ_FL_lock,
2273 -1, // never trigger processing
2274 -1, // no limit on length
2275 Shared_DirtyCardQ_lock,
2276 &JavaThread::dirty_card_queue_set());
2277
2278 // Here we allocate the dummy HeapRegion that is required by the
2279 // G1AllocRegion class.
2280 HeapRegion* dummy_region = _hrm.get_dummy_region();
2281
2282 // We'll re-use the same region whether the alloc region will
2283 // require BOT updates or not and, if it doesn't, then a non-young
2284 // region will complain that it cannot support allocations without
2285 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2286 dummy_region->set_eden();
2287 // Make sure it's full.
2288 dummy_region->set_top(dummy_region->end());
2289 G1AllocRegion::setup(this, dummy_region);
2290
2291 _allocator->init_mutator_alloc_region();
2292
2293 // Do create of the monitoring and management support so that
2294 // values in the heap have been properly initialized.
2295 _g1mm = new G1MonitoringSupport(this);
2296
2297 G1StringDedup::initialize();
2298
2299 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2300 for (uint i = 0; i < ParallelGCThreads; i++) {
2301 new (&_preserved_objs[i]) OopAndMarkOopStack();
2302 }
2303
2304 return JNI_OK;
2305 }
2306
2307 void G1CollectedHeap::stop() {
2308 // Stop all concurrent threads. We do this to make sure these threads
2309 // do not continue to execute and access resources (e.g. gclog_or_tty)
2310 // that are destroyed during shutdown.
2311 _cg1r->stop();
2312 _cmThread->stop();
2313 if (G1StringDedup::is_enabled()) {
2314 G1StringDedup::stop();
2315 }
2316 }
2317
2318 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2319 return HeapRegion::max_region_size();
2320 }
2321
2322 void G1CollectedHeap::post_initialize() {
2323 CollectedHeap::post_initialize();
2324 ref_processing_init();
2325 }
2326
2327 void G1CollectedHeap::ref_processing_init() {
2328 // Reference processing in G1 currently works as follows:
2329 //
2330 // * There are two reference processor instances. One is
2331 // used to record and process discovered references
2332 // during concurrent marking; the other is used to
2333 // record and process references during STW pauses
2334 // (both full and incremental).
2335 // * Both ref processors need to 'span' the entire heap as
2336 // the regions in the collection set may be dotted around.
2337 //
2338 // * For the concurrent marking ref processor:
2339 // * Reference discovery is enabled at initial marking.
2340 // * Reference discovery is disabled and the discovered
2341 // references processed etc during remarking.
2342 // * Reference discovery is MT (see below).
2343 // * Reference discovery requires a barrier (see below).
2344 // * Reference processing may or may not be MT
2345 // (depending on the value of ParallelRefProcEnabled
2346 // and ParallelGCThreads).
2347 // * A full GC disables reference discovery by the CM
2348 // ref processor and abandons any entries on it's
2349 // discovered lists.
2350 //
2351 // * For the STW processor:
2352 // * Non MT discovery is enabled at the start of a full GC.
2353 // * Processing and enqueueing during a full GC is non-MT.
2354 // * During a full GC, references are processed after marking.
2355 //
2356 // * Discovery (may or may not be MT) is enabled at the start
2357 // of an incremental evacuation pause.
2358 // * References are processed near the end of a STW evacuation pause.
2359 // * For both types of GC:
2360 // * Discovery is atomic - i.e. not concurrent.
2361 // * Reference discovery will not need a barrier.
2362
2363 MemRegion mr = reserved_region();
2364
2365 // Concurrent Mark ref processor
2366 _ref_processor_cm =
2367 new ReferenceProcessor(mr, // span
2368 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2369 // mt processing
2370 ParallelGCThreads,
2371 // degree of mt processing
2372 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2373 // mt discovery
2374 MAX2(ParallelGCThreads, ConcGCThreads),
2375 // degree of mt discovery
2376 false,
2377 // Reference discovery is not atomic
2378 &_is_alive_closure_cm);
2379 // is alive closure
2380 // (for efficiency/performance)
2381
2382 // STW ref processor
2383 _ref_processor_stw =
2384 new ReferenceProcessor(mr, // span
2385 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2386 // mt processing
2387 ParallelGCThreads,
2388 // degree of mt processing
2389 (ParallelGCThreads > 1),
2390 // mt discovery
2391 ParallelGCThreads,
2392 // degree of mt discovery
2393 true,
2394 // Reference discovery is atomic
2395 &_is_alive_closure_stw);
2396 // is alive closure
2397 // (for efficiency/performance)
2398 }
2399
2400 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2401 return g1_policy();
2402 }
2403
2404 size_t G1CollectedHeap::capacity() const {
2405 return _hrm.length() * HeapRegion::GrainBytes;
2406 }
2407
2408 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2409 assert(!hr->is_continues_humongous(), "pre-condition");
2410 hr->reset_gc_time_stamp();
2411 if (hr->is_starts_humongous()) {
2412 uint first_index = hr->hrm_index() + 1;
2413 uint last_index = hr->last_hc_index();
2414 for (uint i = first_index; i < last_index; i += 1) {
2415 HeapRegion* chr = region_at(i);
2416 assert(chr->is_continues_humongous(), "sanity");
2417 chr->reset_gc_time_stamp();
2418 }
2419 }
2420 }
2421
2422 #ifndef PRODUCT
2423
2424 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2425 private:
2426 unsigned _gc_time_stamp;
2427 bool _failures;
2428
2429 public:
2430 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2431 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2432
2433 virtual bool doHeapRegion(HeapRegion* hr) {
2434 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2435 if (_gc_time_stamp != region_gc_time_stamp) {
2436 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2437 "expected %d", HR_FORMAT_PARAMS(hr),
2438 region_gc_time_stamp, _gc_time_stamp);
2439 _failures = true;
2440 }
2441 return false;
2442 }
2443
2444 bool failures() { return _failures; }
2445 };
2446
2447 void G1CollectedHeap::check_gc_time_stamps() {
2448 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2449 heap_region_iterate(&cl);
2450 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2451 }
2452 #endif // PRODUCT
2453
2454 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2455 DirtyCardQueue* into_cset_dcq,
2456 bool concurrent,
2457 uint worker_i) {
2458 // Clean cards in the hot card cache
2459 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2460 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2461
2462 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2463 size_t n_completed_buffers = 0;
2464 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2465 n_completed_buffers++;
2466 }
2467 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2468 dcqs.clear_n_completed_buffers();
2469 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2470 }
2471
2472 // Computes the sum of the storage used by the various regions.
2473 size_t G1CollectedHeap::used() const {
2474 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2475 if (_archive_allocator != NULL) {
2476 result += _archive_allocator->used();
2477 }
2478 return result;
2479 }
2480
2481 size_t G1CollectedHeap::used_unlocked() const {
2482 return _summary_bytes_used;
2483 }
2484
2485 class SumUsedClosure: public HeapRegionClosure {
2486 size_t _used;
2487 public:
2488 SumUsedClosure() : _used(0) {}
2489 bool doHeapRegion(HeapRegion* r) {
2490 if (!r->is_continues_humongous()) {
2491 _used += r->used();
2492 }
2493 return false;
2494 }
2495 size_t result() { return _used; }
2496 };
2497
2498 size_t G1CollectedHeap::recalculate_used() const {
2499 double recalculate_used_start = os::elapsedTime();
2500
2501 SumUsedClosure blk;
2502 heap_region_iterate(&blk);
2503
2504 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2505 return blk.result();
2506 }
2507
2508 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2509 switch (cause) {
2510 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2511 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2512 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2513 case GCCause::_g1_humongous_allocation: return true;
2514 case GCCause::_update_allocation_context_stats_inc: return true;
2515 case GCCause::_wb_conc_mark: return true;
2516 default: return false;
2517 }
2518 }
2519
2520 #ifndef PRODUCT
2521 void G1CollectedHeap::allocate_dummy_regions() {
2522 // Let's fill up most of the region
2523 size_t word_size = HeapRegion::GrainWords - 1024;
2524 // And as a result the region we'll allocate will be humongous.
2525 guarantee(is_humongous(word_size), "sanity");
2526
2527 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2528 // Let's use the existing mechanism for the allocation
2529 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2530 AllocationContext::system());
2531 if (dummy_obj != NULL) {
2532 MemRegion mr(dummy_obj, word_size);
2533 CollectedHeap::fill_with_object(mr);
2534 } else {
2535 // If we can't allocate once, we probably cannot allocate
2536 // again. Let's get out of the loop.
2537 break;
2538 }
2539 }
2540 }
2541 #endif // !PRODUCT
2542
2543 void G1CollectedHeap::increment_old_marking_cycles_started() {
2544 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2545 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2546 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2547 _old_marking_cycles_started, _old_marking_cycles_completed));
2548
2549 _old_marking_cycles_started++;
2550 }
2551
2552 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2553 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2554
2555 // We assume that if concurrent == true, then the caller is a
2556 // concurrent thread that was joined the Suspendible Thread
2557 // Set. If there's ever a cheap way to check this, we should add an
2558 // assert here.
2559
2560 // Given that this method is called at the end of a Full GC or of a
2561 // concurrent cycle, and those can be nested (i.e., a Full GC can
2562 // interrupt a concurrent cycle), the number of full collections
2563 // completed should be either one (in the case where there was no
2564 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2565 // behind the number of full collections started.
2566
2567 // This is the case for the inner caller, i.e. a Full GC.
2568 assert(concurrent ||
2569 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2570 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2571 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2572 "is inconsistent with _old_marking_cycles_completed = %u",
2573 _old_marking_cycles_started, _old_marking_cycles_completed));
2574
2575 // This is the case for the outer caller, i.e. the concurrent cycle.
2576 assert(!concurrent ||
2577 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2578 err_msg("for outer caller (concurrent cycle): "
2579 "_old_marking_cycles_started = %u "
2580 "is inconsistent with _old_marking_cycles_completed = %u",
2581 _old_marking_cycles_started, _old_marking_cycles_completed));
2582
2583 _old_marking_cycles_completed += 1;
2584
2585 // We need to clear the "in_progress" flag in the CM thread before
2586 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2587 // is set) so that if a waiter requests another System.gc() it doesn't
2588 // incorrectly see that a marking cycle is still in progress.
2589 if (concurrent) {
2590 _cmThread->set_idle();
2591 }
2592
2593 // This notify_all() will ensure that a thread that called
2594 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2595 // and it's waiting for a full GC to finish will be woken up. It is
2596 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2597 FullGCCount_lock->notify_all();
2598 }
2599
2600 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2601 collector_state()->set_concurrent_cycle_started(true);
2602 _gc_timer_cm->register_gc_start(start_time);
2603
2604 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2605 trace_heap_before_gc(_gc_tracer_cm);
2606 }
2607
2608 void G1CollectedHeap::register_concurrent_cycle_end() {
2609 if (collector_state()->concurrent_cycle_started()) {
2610 if (_cm->has_aborted()) {
2611 _gc_tracer_cm->report_concurrent_mode_failure();
2612 }
2613
2614 _gc_timer_cm->register_gc_end();
2615 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2616
2617 // Clear state variables to prepare for the next concurrent cycle.
2618 collector_state()->set_concurrent_cycle_started(false);
2619 _heap_summary_sent = false;
2620 }
2621 }
2622
2623 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2624 if (collector_state()->concurrent_cycle_started()) {
2625 // This function can be called when:
2626 // the cleanup pause is run
2627 // the concurrent cycle is aborted before the cleanup pause.
2628 // the concurrent cycle is aborted after the cleanup pause,
2629 // but before the concurrent cycle end has been registered.
2630 // Make sure that we only send the heap information once.
2631 if (!_heap_summary_sent) {
2632 trace_heap_after_gc(_gc_tracer_cm);
2633 _heap_summary_sent = true;
2634 }
2635 }
2636 }
2637
2638 void G1CollectedHeap::collect(GCCause::Cause cause) {
2639 assert_heap_not_locked();
2640
2641 uint gc_count_before;
2642 uint old_marking_count_before;
2643 uint full_gc_count_before;
2644 bool retry_gc;
2645
2646 do {
2647 retry_gc = false;
2648
2649 {
2650 MutexLocker ml(Heap_lock);
2651
2652 // Read the GC count while holding the Heap_lock
2653 gc_count_before = total_collections();
2654 full_gc_count_before = total_full_collections();
2655 old_marking_count_before = _old_marking_cycles_started;
2656 }
2657
2658 if (should_do_concurrent_full_gc(cause)) {
2659 // Schedule an initial-mark evacuation pause that will start a
2660 // concurrent cycle. We're setting word_size to 0 which means that
2661 // we are not requesting a post-GC allocation.
2662 VM_G1IncCollectionPause op(gc_count_before,
2663 0, /* word_size */
2664 true, /* should_initiate_conc_mark */
2665 g1_policy()->max_pause_time_ms(),
2666 cause);
2667 op.set_allocation_context(AllocationContext::current());
2668
2669 VMThread::execute(&op);
2670 if (!op.pause_succeeded()) {
2671 if (old_marking_count_before == _old_marking_cycles_started) {
2672 retry_gc = op.should_retry_gc();
2673 } else {
2674 // A Full GC happened while we were trying to schedule the
2675 // initial-mark GC. No point in starting a new cycle given
2676 // that the whole heap was collected anyway.
2677 }
2678
2679 if (retry_gc) {
2680 if (GC_locker::is_active_and_needs_gc()) {
2681 GC_locker::stall_until_clear();
2682 }
2683 }
2684 }
2685 } else {
2686 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2687 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2688
2689 // Schedule a standard evacuation pause. We're setting word_size
2690 // to 0 which means that we are not requesting a post-GC allocation.
2691 VM_G1IncCollectionPause op(gc_count_before,
2692 0, /* word_size */
2693 false, /* should_initiate_conc_mark */
2694 g1_policy()->max_pause_time_ms(),
2695 cause);
2696 VMThread::execute(&op);
2697 } else {
2698 // Schedule a Full GC.
2699 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2700 VMThread::execute(&op);
2701 }
2702 }
2703 } while (retry_gc);
2704 }
2705
2706 bool G1CollectedHeap::is_in(const void* p) const {
2707 if (_hrm.reserved().contains(p)) {
2708 // Given that we know that p is in the reserved space,
2709 // heap_region_containing_raw() should successfully
2710 // return the containing region.
2711 HeapRegion* hr = heap_region_containing_raw(p);
2712 return hr->is_in(p);
2713 } else {
2714 return false;
2715 }
2716 }
2717
2718 #ifdef ASSERT
2719 bool G1CollectedHeap::is_in_exact(const void* p) const {
2720 bool contains = reserved_region().contains(p);
2721 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2722 if (contains && available) {
2723 return true;
2724 } else {
2725 return false;
2726 }
2727 }
2728 #endif
2729
2730 bool G1CollectedHeap::obj_in_cs(oop obj) {
2731 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2732 return r != NULL && r->in_collection_set();
2733 }
2734
2735 // Iteration functions.
2736
2737 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2738
2739 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2740 ExtendedOopClosure* _cl;
2741 public:
2742 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2743 bool doHeapRegion(HeapRegion* r) {
2744 if (!r->is_continues_humongous()) {
2745 r->oop_iterate(_cl);
2746 }
2747 return false;
2748 }
2749 };
2750
2751 // Iterates an ObjectClosure over all objects within a HeapRegion.
2752
2753 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2754 ObjectClosure* _cl;
2755 public:
2756 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2757 bool doHeapRegion(HeapRegion* r) {
2758 if (!r->is_continues_humongous()) {
2759 r->object_iterate(_cl);
2760 }
2761 return false;
2762 }
2763 };
2764
2765 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2766 IterateObjectClosureRegionClosure blk(cl);
2767 heap_region_iterate(&blk);
2768 }
2769
2770 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2771 _hrm.iterate(cl);
2772 }
2773
2774 void
2775 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2776 uint worker_id,
2777 HeapRegionClaimer *hrclaimer,
2778 bool concurrent) const {
2779 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2780 }
2781
2782 // Clear the cached CSet starting regions and (more importantly)
2783 // the time stamps. Called when we reset the GC time stamp.
2784 void G1CollectedHeap::clear_cset_start_regions() {
2785 assert(_worker_cset_start_region != NULL, "sanity");
2786 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2787
2788 for (uint i = 0; i < ParallelGCThreads; i++) {
2789 _worker_cset_start_region[i] = NULL;
2790 _worker_cset_start_region_time_stamp[i] = 0;
2791 }
2792 }
2793
2794 // Given the id of a worker, obtain or calculate a suitable
2795 // starting region for iterating over the current collection set.
2796 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2797 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2798
2799 HeapRegion* result = NULL;
2800 unsigned gc_time_stamp = get_gc_time_stamp();
2801
2802 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2803 // Cached starting region for current worker was set
2804 // during the current pause - so it's valid.
2805 // Note: the cached starting heap region may be NULL
2806 // (when the collection set is empty).
2807 result = _worker_cset_start_region[worker_i];
2808 assert(result == NULL || result->in_collection_set(), "sanity");
2809 return result;
2810 }
2811
2812 // The cached entry was not valid so let's calculate
2813 // a suitable starting heap region for this worker.
2814
2815 // We want the parallel threads to start their collection
2816 // set iteration at different collection set regions to
2817 // avoid contention.
2818 // If we have:
2819 // n collection set regions
2820 // p threads
2821 // Then thread t will start at region floor ((t * n) / p)
2822
2823 result = g1_policy()->collection_set();
2824 uint cs_size = g1_policy()->cset_region_length();
2825 uint active_workers = workers()->active_workers();
2826
2827 uint end_ind = (cs_size * worker_i) / active_workers;
2828 uint start_ind = 0;
2829
2830 if (worker_i > 0 &&
2831 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2832 // Previous workers starting region is valid
2833 // so let's iterate from there
2834 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2835 result = _worker_cset_start_region[worker_i - 1];
2836 }
2837
2838 for (uint i = start_ind; i < end_ind; i++) {
2839 result = result->next_in_collection_set();
2840 }
2841
2842 // Note: the calculated starting heap region may be NULL
2843 // (when the collection set is empty).
2844 assert(result == NULL || result->in_collection_set(), "sanity");
2845 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2846 "should be updated only once per pause");
2847 _worker_cset_start_region[worker_i] = result;
2848 OrderAccess::storestore();
2849 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2850 return result;
2851 }
2852
2853 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2854 HeapRegion* r = g1_policy()->collection_set();
2855 while (r != NULL) {
2856 HeapRegion* next = r->next_in_collection_set();
2857 if (cl->doHeapRegion(r)) {
2858 cl->incomplete();
2859 return;
2860 }
2861 r = next;
2862 }
2863 }
2864
2865 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2866 HeapRegionClosure *cl) {
2867 if (r == NULL) {
2868 // The CSet is empty so there's nothing to do.
2869 return;
2870 }
2871
2872 assert(r->in_collection_set(),
2873 "Start region must be a member of the collection set.");
2874 HeapRegion* cur = r;
2875 while (cur != NULL) {
2876 HeapRegion* next = cur->next_in_collection_set();
2877 if (cl->doHeapRegion(cur) && false) {
2878 cl->incomplete();
2879 return;
2880 }
2881 cur = next;
2882 }
2883 cur = g1_policy()->collection_set();
2884 while (cur != r) {
2885 HeapRegion* next = cur->next_in_collection_set();
2886 if (cl->doHeapRegion(cur) && false) {
2887 cl->incomplete();
2888 return;
2889 }
2890 cur = next;
2891 }
2892 }
2893
2894 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2895 HeapRegion* result = _hrm.next_region_in_heap(from);
2896 while (result != NULL && result->is_pinned()) {
2897 result = _hrm.next_region_in_heap(result);
2898 }
2899 return result;
2900 }
2901
2902 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2903 HeapRegion* hr = heap_region_containing(addr);
2904 return hr->block_start(addr);
2905 }
2906
2907 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2908 HeapRegion* hr = heap_region_containing(addr);
2909 return hr->block_size(addr);
2910 }
2911
2912 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2913 HeapRegion* hr = heap_region_containing(addr);
2914 return hr->block_is_obj(addr);
2915 }
2916
2917 bool G1CollectedHeap::supports_tlab_allocation() const {
2918 return true;
2919 }
2920
2921 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2922 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2923 }
2924
2925 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2926 return young_list()->eden_used_bytes();
2927 }
2928
2929 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2930 // must be equal to the humongous object limit.
2931 size_t G1CollectedHeap::max_tlab_size() const {
2932 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2933 }
2934
2935 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2936 AllocationContext_t context = AllocationContext::current();
2937 return _allocator->unsafe_max_tlab_alloc(context);
2938 }
2939
2940 size_t G1CollectedHeap::max_capacity() const {
2941 return _hrm.reserved().byte_size();
2942 }
2943
2944 jlong G1CollectedHeap::millis_since_last_gc() {
2945 // assert(false, "NYI");
2946 return 0;
2947 }
2948
2949 void G1CollectedHeap::prepare_for_verify() {
2950 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2951 ensure_parsability(false);
2952 }
2953 g1_rem_set()->prepare_for_verify();
2954 }
2955
2956 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2957 VerifyOption vo) {
2958 switch (vo) {
2959 case VerifyOption_G1UsePrevMarking:
2960 return hr->obj_allocated_since_prev_marking(obj);
2961 case VerifyOption_G1UseNextMarking:
2962 return hr->obj_allocated_since_next_marking(obj);
2963 case VerifyOption_G1UseMarkWord:
2964 return false;
2965 default:
2966 ShouldNotReachHere();
2967 }
2968 return false; // keep some compilers happy
2969 }
2970
2971 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2972 switch (vo) {
2973 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2974 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2975 case VerifyOption_G1UseMarkWord: return NULL;
2976 default: ShouldNotReachHere();
2977 }
2978 return NULL; // keep some compilers happy
2979 }
2980
2981 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2982 switch (vo) {
2983 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2984 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2985 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2986 default: ShouldNotReachHere();
2987 }
2988 return false; // keep some compilers happy
2989 }
2990
2991 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2992 switch (vo) {
2993 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2994 case VerifyOption_G1UseNextMarking: return "NTAMS";
2995 case VerifyOption_G1UseMarkWord: return "NONE";
2996 default: ShouldNotReachHere();
2997 }
2998 return NULL; // keep some compilers happy
2999 }
3000
3001 class VerifyRootsClosure: public OopClosure {
3002 private:
3003 G1CollectedHeap* _g1h;
3004 VerifyOption _vo;
3005 bool _failures;
3006 public:
3007 // _vo == UsePrevMarking -> use "prev" marking information,
3008 // _vo == UseNextMarking -> use "next" marking information,
3009 // _vo == UseMarkWord -> use mark word from object header.
3010 VerifyRootsClosure(VerifyOption vo) :
3011 _g1h(G1CollectedHeap::heap()),
3012 _vo(vo),
3013 _failures(false) { }
3014
3015 bool failures() { return _failures; }
3016
3017 template <class T> void do_oop_nv(T* p) {
3018 T heap_oop = oopDesc::load_heap_oop(p);
3019 if (!oopDesc::is_null(heap_oop)) {
3020 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3021 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3022 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3023 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3024 if (_vo == VerifyOption_G1UseMarkWord) {
3025 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3026 }
3027 obj->print_on(gclog_or_tty);
3028 _failures = true;
3029 }
3030 }
3031 }
3032
3033 void do_oop(oop* p) { do_oop_nv(p); }
3034 void do_oop(narrowOop* p) { do_oop_nv(p); }
3035 };
3036
3037 class G1VerifyCodeRootOopClosure: public OopClosure {
3038 G1CollectedHeap* _g1h;
3039 OopClosure* _root_cl;
3040 nmethod* _nm;
3041 VerifyOption _vo;
3042 bool _failures;
3043
3044 template <class T> void do_oop_work(T* p) {
3045 // First verify that this root is live
3046 _root_cl->do_oop(p);
3047
3048 if (!G1VerifyHeapRegionCodeRoots) {
3049 // We're not verifying the code roots attached to heap region.
3050 return;
3051 }
3052
3053 // Don't check the code roots during marking verification in a full GC
3054 if (_vo == VerifyOption_G1UseMarkWord) {
3055 return;
3056 }
3057
3058 // Now verify that the current nmethod (which contains p) is
3059 // in the code root list of the heap region containing the
3060 // object referenced by p.
3061
3062 T heap_oop = oopDesc::load_heap_oop(p);
3063 if (!oopDesc::is_null(heap_oop)) {
3064 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3065
3066 // Now fetch the region containing the object
3067 HeapRegion* hr = _g1h->heap_region_containing(obj);
3068 HeapRegionRemSet* hrrs = hr->rem_set();
3069 // Verify that the strong code root list for this region
3070 // contains the nmethod
3071 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3072 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3073 "from nmethod " PTR_FORMAT " not in strong "
3074 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3075 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3076 _failures = true;
3077 }
3078 }
3079 }
3080
3081 public:
3082 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3083 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3084
3085 void do_oop(oop* p) { do_oop_work(p); }
3086 void do_oop(narrowOop* p) { do_oop_work(p); }
3087
3088 void set_nmethod(nmethod* nm) { _nm = nm; }
3089 bool failures() { return _failures; }
3090 };
3091
3092 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3093 G1VerifyCodeRootOopClosure* _oop_cl;
3094
3095 public:
3096 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3097 _oop_cl(oop_cl) {}
3098
3099 void do_code_blob(CodeBlob* cb) {
3100 nmethod* nm = cb->as_nmethod_or_null();
3101 if (nm != NULL) {
3102 _oop_cl->set_nmethod(nm);
3103 nm->oops_do(_oop_cl);
3104 }
3105 }
3106 };
3107
3108 class YoungRefCounterClosure : public OopClosure {
3109 G1CollectedHeap* _g1h;
3110 int _count;
3111 public:
3112 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3113 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3114 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3115
3116 int count() { return _count; }
3117 void reset_count() { _count = 0; };
3118 };
3119
3120 class VerifyKlassClosure: public KlassClosure {
3121 YoungRefCounterClosure _young_ref_counter_closure;
3122 OopClosure *_oop_closure;
3123 public:
3124 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3125 void do_klass(Klass* k) {
3126 k->oops_do(_oop_closure);
3127
3128 _young_ref_counter_closure.reset_count();
3129 k->oops_do(&_young_ref_counter_closure);
3130 if (_young_ref_counter_closure.count() > 0) {
3131 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3132 }
3133 }
3134 };
3135
3136 class VerifyLivenessOopClosure: public OopClosure {
3137 G1CollectedHeap* _g1h;
3138 VerifyOption _vo;
3139 public:
3140 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3141 _g1h(g1h), _vo(vo)
3142 { }
3143 void do_oop(narrowOop *p) { do_oop_work(p); }
3144 void do_oop( oop *p) { do_oop_work(p); }
3145
3146 template <class T> void do_oop_work(T *p) {
3147 oop obj = oopDesc::load_decode_heap_oop(p);
3148 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3149 "Dead object referenced by a not dead object");
3150 }
3151 };
3152
3153 class VerifyObjsInRegionClosure: public ObjectClosure {
3154 private:
3155 G1CollectedHeap* _g1h;
3156 size_t _live_bytes;
3157 HeapRegion *_hr;
3158 VerifyOption _vo;
3159 public:
3160 // _vo == UsePrevMarking -> use "prev" marking information,
3161 // _vo == UseNextMarking -> use "next" marking information,
3162 // _vo == UseMarkWord -> use mark word from object header.
3163 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3164 : _live_bytes(0), _hr(hr), _vo(vo) {
3165 _g1h = G1CollectedHeap::heap();
3166 }
3167 void do_object(oop o) {
3168 VerifyLivenessOopClosure isLive(_g1h, _vo);
3169 assert(o != NULL, "Huh?");
3170 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3171 // If the object is alive according to the mark word,
3172 // then verify that the marking information agrees.
3173 // Note we can't verify the contra-positive of the
3174 // above: if the object is dead (according to the mark
3175 // word), it may not be marked, or may have been marked
3176 // but has since became dead, or may have been allocated
3177 // since the last marking.
3178 if (_vo == VerifyOption_G1UseMarkWord) {
3179 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3180 }
3181
3182 o->oop_iterate_no_header(&isLive);
3183 if (!_hr->obj_allocated_since_prev_marking(o)) {
3184 size_t obj_size = o->size(); // Make sure we don't overflow
3185 _live_bytes += (obj_size * HeapWordSize);
3186 }
3187 }
3188 }
3189 size_t live_bytes() { return _live_bytes; }
3190 };
3191
3192 class VerifyArchiveOopClosure: public OopClosure {
3193 public:
3194 VerifyArchiveOopClosure(HeapRegion *hr) { }
3195 void do_oop(narrowOop *p) { do_oop_work(p); }
3196 void do_oop( oop *p) { do_oop_work(p); }
3197
3198 template <class T> void do_oop_work(T *p) {
3199 oop obj = oopDesc::load_decode_heap_oop(p);
3200 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3201 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3202 p2i(p), p2i(obj)));
3203 }
3204 };
3205
3206 class VerifyArchiveRegionClosure: public ObjectClosure {
3207 public:
3208 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3209 // Verify that all object pointers are to archive regions.
3210 void do_object(oop o) {
3211 VerifyArchiveOopClosure checkOop(NULL);
3212 assert(o != NULL, "Should not be here for NULL oops");
3213 o->oop_iterate_no_header(&checkOop);
3214 }
3215 };
3216
3217 class VerifyRegionClosure: public HeapRegionClosure {
3218 private:
3219 bool _par;
3220 VerifyOption _vo;
3221 bool _failures;
3222 public:
3223 // _vo == UsePrevMarking -> use "prev" marking information,
3224 // _vo == UseNextMarking -> use "next" marking information,
3225 // _vo == UseMarkWord -> use mark word from object header.
3226 VerifyRegionClosure(bool par, VerifyOption vo)
3227 : _par(par),
3228 _vo(vo),
3229 _failures(false) {}
3230
3231 bool failures() {
3232 return _failures;
3233 }
3234
3235 bool doHeapRegion(HeapRegion* r) {
3236 // For archive regions, verify there are no heap pointers to
3237 // non-pinned regions. For all others, verify liveness info.
3238 if (r->is_archive()) {
3239 VerifyArchiveRegionClosure verify_oop_pointers(r);
3240 r->object_iterate(&verify_oop_pointers);
3241 return true;
3242 }
3243 if (!r->is_continues_humongous()) {
3244 bool failures = false;
3245 r->verify(_vo, &failures);
3246 if (failures) {
3247 _failures = true;
3248 } else {
3249 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3250 r->object_iterate(¬_dead_yet_cl);
3251 if (_vo != VerifyOption_G1UseNextMarking) {
3252 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3253 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3254 "max_live_bytes " SIZE_FORMAT " "
3255 "< calculated " SIZE_FORMAT,
3256 p2i(r->bottom()), p2i(r->end()),
3257 r->max_live_bytes(),
3258 not_dead_yet_cl.live_bytes());
3259 _failures = true;
3260 }
3261 } else {
3262 // When vo == UseNextMarking we cannot currently do a sanity
3263 // check on the live bytes as the calculation has not been
3264 // finalized yet.
3265 }
3266 }
3267 }
3268 return false; // stop the region iteration if we hit a failure
3269 }
3270 };
3271
3272 // This is the task used for parallel verification of the heap regions
3273
3274 class G1ParVerifyTask: public AbstractGangTask {
3275 private:
3276 G1CollectedHeap* _g1h;
3277 VerifyOption _vo;
3278 bool _failures;
3279 HeapRegionClaimer _hrclaimer;
3280
3281 public:
3282 // _vo == UsePrevMarking -> use "prev" marking information,
3283 // _vo == UseNextMarking -> use "next" marking information,
3284 // _vo == UseMarkWord -> use mark word from object header.
3285 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3286 AbstractGangTask("Parallel verify task"),
3287 _g1h(g1h),
3288 _vo(vo),
3289 _failures(false),
3290 _hrclaimer(g1h->workers()->active_workers()) {}
3291
3292 bool failures() {
3293 return _failures;
3294 }
3295
3296 void work(uint worker_id) {
3297 HandleMark hm;
3298 VerifyRegionClosure blk(true, _vo);
3299 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3300 if (blk.failures()) {
3301 _failures = true;
3302 }
3303 }
3304 };
3305
3306 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3307 if (SafepointSynchronize::is_at_safepoint()) {
3308 assert(Thread::current()->is_VM_thread(),
3309 "Expected to be executed serially by the VM thread at this point");
3310
3311 if (!silent) { gclog_or_tty->print("Roots "); }
3312 VerifyRootsClosure rootsCl(vo);
3313 VerifyKlassClosure klassCl(this, &rootsCl);
3314 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3315
3316 // We apply the relevant closures to all the oops in the
3317 // system dictionary, class loader data graph, the string table
3318 // and the nmethods in the code cache.
3319 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3320 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3321
3322 {
3323 G1RootProcessor root_processor(this, 1);
3324 root_processor.process_all_roots(&rootsCl,
3325 &cldCl,
3326 &blobsCl);
3327 }
3328
3329 bool failures = rootsCl.failures() || codeRootsCl.failures();
3330
3331 if (vo != VerifyOption_G1UseMarkWord) {
3332 // If we're verifying during a full GC then the region sets
3333 // will have been torn down at the start of the GC. Therefore
3334 // verifying the region sets will fail. So we only verify
3335 // the region sets when not in a full GC.
3336 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3337 verify_region_sets();
3338 }
3339
3340 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3341 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3342
3343 G1ParVerifyTask task(this, vo);
3344 workers()->run_task(&task);
3345 if (task.failures()) {
3346 failures = true;
3347 }
3348
3349 } else {
3350 VerifyRegionClosure blk(false, vo);
3351 heap_region_iterate(&blk);
3352 if (blk.failures()) {
3353 failures = true;
3354 }
3355 }
3356
3357 if (G1StringDedup::is_enabled()) {
3358 if (!silent) gclog_or_tty->print("StrDedup ");
3359 G1StringDedup::verify();
3360 }
3361
3362 if (failures) {
3363 gclog_or_tty->print_cr("Heap:");
3364 // It helps to have the per-region information in the output to
3365 // help us track down what went wrong. This is why we call
3366 // print_extended_on() instead of print_on().
3367 print_extended_on(gclog_or_tty);
3368 gclog_or_tty->cr();
3369 gclog_or_tty->flush();
3370 }
3371 guarantee(!failures, "there should not have been any failures");
3372 } else {
3373 if (!silent) {
3374 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3375 if (G1StringDedup::is_enabled()) {
3376 gclog_or_tty->print(", StrDedup");
3377 }
3378 gclog_or_tty->print(") ");
3379 }
3380 }
3381 }
3382
3383 void G1CollectedHeap::verify(bool silent) {
3384 verify(silent, VerifyOption_G1UsePrevMarking);
3385 }
3386
3387 double G1CollectedHeap::verify(bool guard, const char* msg) {
3388 double verify_time_ms = 0.0;
3389
3390 if (guard && total_collections() >= VerifyGCStartAt) {
3391 double verify_start = os::elapsedTime();
3392 HandleMark hm; // Discard invalid handles created during verification
3393 prepare_for_verify();
3394 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3395 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3396 }
3397
3398 return verify_time_ms;
3399 }
3400
3401 void G1CollectedHeap::verify_before_gc() {
3402 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3403 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3404 }
3405
3406 void G1CollectedHeap::verify_after_gc() {
3407 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3408 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3409 }
3410
3411 class PrintRegionClosure: public HeapRegionClosure {
3412 outputStream* _st;
3413 public:
3414 PrintRegionClosure(outputStream* st) : _st(st) {}
3415 bool doHeapRegion(HeapRegion* r) {
3416 r->print_on(_st);
3417 return false;
3418 }
3419 };
3420
3421 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3422 const HeapRegion* hr,
3423 const VerifyOption vo) const {
3424 switch (vo) {
3425 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3426 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3427 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3428 default: ShouldNotReachHere();
3429 }
3430 return false; // keep some compilers happy
3431 }
3432
3433 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3434 const VerifyOption vo) const {
3435 switch (vo) {
3436 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3437 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3438 case VerifyOption_G1UseMarkWord: {
3439 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3440 return !obj->is_gc_marked() && !hr->is_archive();
3441 }
3442 default: ShouldNotReachHere();
3443 }
3444 return false; // keep some compilers happy
3445 }
3446
3447 void G1CollectedHeap::print_on(outputStream* st) const {
3448 st->print(" %-20s", "garbage-first heap");
3449 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3450 capacity()/K, used_unlocked()/K);
3451 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3452 p2i(_hrm.reserved().start()),
3453 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3454 p2i(_hrm.reserved().end()));
3455 st->cr();
3456 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3457 uint young_regions = _young_list->length();
3458 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3459 (size_t) young_regions * HeapRegion::GrainBytes / K);
3460 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3461 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3462 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3463 st->cr();
3464 MetaspaceAux::print_on(st);
3465 }
3466
3467 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3468 print_on(st);
3469
3470 // Print the per-region information.
3471 st->cr();
3472 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3473 "HS=humongous(starts), HC=humongous(continues), "
3474 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3475 "PTAMS=previous top-at-mark-start, "
3476 "NTAMS=next top-at-mark-start)");
3477 PrintRegionClosure blk(st);
3478 heap_region_iterate(&blk);
3479 }
3480
3481 void G1CollectedHeap::print_on_error(outputStream* st) const {
3482 this->CollectedHeap::print_on_error(st);
3483
3484 if (_cm != NULL) {
3485 st->cr();
3486 _cm->print_on_error(st);
3487 }
3488 }
3489
3490 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3491 workers()->print_worker_threads_on(st);
3492 _cmThread->print_on(st);
3493 st->cr();
3494 _cm->print_worker_threads_on(st);
3495 _cg1r->print_worker_threads_on(st);
3496 if (G1StringDedup::is_enabled()) {
3497 G1StringDedup::print_worker_threads_on(st);
3498 }
3499 }
3500
3501 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3502 workers()->threads_do(tc);
3503 tc->do_thread(_cmThread);
3504 _cg1r->threads_do(tc);
3505 if (G1StringDedup::is_enabled()) {
3506 G1StringDedup::threads_do(tc);
3507 }
3508 }
3509
3510 void G1CollectedHeap::print_tracing_info() const {
3511 // We'll overload this to mean "trace GC pause statistics."
3512 if (TraceYoungGenTime || TraceOldGenTime) {
3513 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3514 // to that.
3515 g1_policy()->print_tracing_info();
3516 }
3517 if (G1SummarizeRSetStats) {
3518 g1_rem_set()->print_summary_info();
3519 }
3520 if (G1SummarizeConcMark) {
3521 concurrent_mark()->print_summary_info();
3522 }
3523 g1_policy()->print_yg_surv_rate_info();
3524 }
3525
3526 #ifndef PRODUCT
3527 // Helpful for debugging RSet issues.
3528
3529 class PrintRSetsClosure : public HeapRegionClosure {
3530 private:
3531 const char* _msg;
3532 size_t _occupied_sum;
3533
3534 public:
3535 bool doHeapRegion(HeapRegion* r) {
3536 HeapRegionRemSet* hrrs = r->rem_set();
3537 size_t occupied = hrrs->occupied();
3538 _occupied_sum += occupied;
3539
3540 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3541 HR_FORMAT_PARAMS(r));
3542 if (occupied == 0) {
3543 gclog_or_tty->print_cr(" RSet is empty");
3544 } else {
3545 hrrs->print();
3546 }
3547 gclog_or_tty->print_cr("----------");
3548 return false;
3549 }
3550
3551 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3552 gclog_or_tty->cr();
3553 gclog_or_tty->print_cr("========================================");
3554 gclog_or_tty->print_cr("%s", msg);
3555 gclog_or_tty->cr();
3556 }
3557
3558 ~PrintRSetsClosure() {
3559 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3560 gclog_or_tty->print_cr("========================================");
3561 gclog_or_tty->cr();
3562 }
3563 };
3564
3565 void G1CollectedHeap::print_cset_rsets() {
3566 PrintRSetsClosure cl("Printing CSet RSets");
3567 collection_set_iterate(&cl);
3568 }
3569
3570 void G1CollectedHeap::print_all_rsets() {
3571 PrintRSetsClosure cl("Printing All RSets");;
3572 heap_region_iterate(&cl);
3573 }
3574 #endif // PRODUCT
3575
3576 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3577 YoungList* young_list = heap()->young_list();
3578
3579 size_t eden_used_bytes = young_list->eden_used_bytes();
3580 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3581
3582 size_t eden_capacity_bytes =
3583 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3584
3585 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3586 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3587 }
3588
3589 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3590 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3591 stats->unused(), stats->used(), stats->region_end_waste(),
3592 stats->regions_filled(), stats->direct_allocated(),
3593 stats->failure_used(), stats->failure_waste());
3594 }
3595
3596 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3597 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3598 gc_tracer->report_gc_heap_summary(when, heap_summary);
3599
3600 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3601 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3602 }
3603
3604
3605 G1CollectedHeap* G1CollectedHeap::heap() {
3606 CollectedHeap* heap = Universe::heap();
3607 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3608 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3609 return (G1CollectedHeap*)heap;
3610 }
3611
3612 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3613 // always_do_update_barrier = false;
3614 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3615 // Fill TLAB's and such
3616 accumulate_statistics_all_tlabs();
3617 ensure_parsability(true);
3618
3619 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3620 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3621 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3622 }
3623 }
3624
3625 void G1CollectedHeap::gc_epilogue(bool full) {
3626
3627 if (G1SummarizeRSetStats &&
3628 (G1SummarizeRSetStatsPeriod > 0) &&
3629 // we are at the end of the GC. Total collections has already been increased.
3630 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3631 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3632 }
3633
3634 // FIXME: what is this about?
3635 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3636 // is set.
3637 #if defined(COMPILER2) || INCLUDE_JVMCI
3638 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3639 #endif
3640 // always_do_update_barrier = true;
3641
3642 resize_all_tlabs();
3643 allocation_context_stats().update(full);
3644
3645 // We have just completed a GC. Update the soft reference
3646 // policy with the new heap occupancy
3647 Universe::update_heap_info_at_gc();
3648 }
3649
3650 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3651 uint gc_count_before,
3652 bool* succeeded,
3653 GCCause::Cause gc_cause) {
3654 assert_heap_not_locked_and_not_at_safepoint();
3655 g1_policy()->record_stop_world_start();
3656 VM_G1IncCollectionPause op(gc_count_before,
3657 word_size,
3658 false, /* should_initiate_conc_mark */
3659 g1_policy()->max_pause_time_ms(),
3660 gc_cause);
3661
3662 op.set_allocation_context(AllocationContext::current());
3663 VMThread::execute(&op);
3664
3665 HeapWord* result = op.result();
3666 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3667 assert(result == NULL || ret_succeeded,
3668 "the result should be NULL if the VM did not succeed");
3669 *succeeded = ret_succeeded;
3670
3671 assert_heap_not_locked();
3672 return result;
3673 }
3674
3675 void
3676 G1CollectedHeap::doConcurrentMark() {
3677 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3678 if (!_cmThread->in_progress()) {
3679 _cmThread->set_started();
3680 CGC_lock->notify();
3681 }
3682 }
3683
3684 size_t G1CollectedHeap::pending_card_num() {
3685 size_t extra_cards = 0;
3686 JavaThread *curr = Threads::first();
3687 while (curr != NULL) {
3688 DirtyCardQueue& dcq = curr->dirty_card_queue();
3689 extra_cards += dcq.size();
3690 curr = curr->next();
3691 }
3692 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3693 size_t buffer_size = dcqs.buffer_size();
3694 size_t buffer_num = dcqs.completed_buffers_num();
3695
3696 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3697 // in bytes - not the number of 'entries'. We need to convert
3698 // into a number of cards.
3699 return (buffer_size * buffer_num + extra_cards) / oopSize;
3700 }
3701
3702 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3703 private:
3704 size_t _total_humongous;
3705 size_t _candidate_humongous;
3706
3707 DirtyCardQueue _dcq;
3708
3709 // We don't nominate objects with many remembered set entries, on
3710 // the assumption that such objects are likely still live.
3711 bool is_remset_small(HeapRegion* region) const {
3712 HeapRegionRemSet* const rset = region->rem_set();
3713 return G1EagerReclaimHumongousObjectsWithStaleRefs
3714 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3715 : rset->is_empty();
3716 }
3717
3718 bool is_typeArray_region(HeapRegion* region) const {
3719 return oop(region->bottom())->is_typeArray();
3720 }
3721
3722 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3723 assert(region->is_starts_humongous(), "Must start a humongous object");
3724
3725 // Candidate selection must satisfy the following constraints
3726 // while concurrent marking is in progress:
3727 //
3728 // * In order to maintain SATB invariants, an object must not be
3729 // reclaimed if it was allocated before the start of marking and
3730 // has not had its references scanned. Such an object must have
3731 // its references (including type metadata) scanned to ensure no
3732 // live objects are missed by the marking process. Objects
3733 // allocated after the start of concurrent marking don't need to
3734 // be scanned.
3735 //
3736 // * An object must not be reclaimed if it is on the concurrent
3737 // mark stack. Objects allocated after the start of concurrent
3738 // marking are never pushed on the mark stack.
3739 //
3740 // Nominating only objects allocated after the start of concurrent
3741 // marking is sufficient to meet both constraints. This may miss
3742 // some objects that satisfy the constraints, but the marking data
3743 // structures don't support efficiently performing the needed
3744 // additional tests or scrubbing of the mark stack.
3745 //
3746 // However, we presently only nominate is_typeArray() objects.
3747 // A humongous object containing references induces remembered
3748 // set entries on other regions. In order to reclaim such an
3749 // object, those remembered sets would need to be cleaned up.
3750 //
3751 // We also treat is_typeArray() objects specially, allowing them
3752 // to be reclaimed even if allocated before the start of
3753 // concurrent mark. For this we rely on mark stack insertion to
3754 // exclude is_typeArray() objects, preventing reclaiming an object
3755 // that is in the mark stack. We also rely on the metadata for
3756 // such objects to be built-in and so ensured to be kept live.
3757 // Frequent allocation and drop of large binary blobs is an
3758 // important use case for eager reclaim, and this special handling
3759 // may reduce needed headroom.
3760
3761 return is_typeArray_region(region) && is_remset_small(region);
3762 }
3763
3764 public:
3765 RegisterHumongousWithInCSetFastTestClosure()
3766 : _total_humongous(0),
3767 _candidate_humongous(0),
3768 _dcq(&JavaThread::dirty_card_queue_set()) {
3769 }
3770
3771 virtual bool doHeapRegion(HeapRegion* r) {
3772 if (!r->is_starts_humongous()) {
3773 return false;
3774 }
3775 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3776
3777 bool is_candidate = humongous_region_is_candidate(g1h, r);
3778 uint rindex = r->hrm_index();
3779 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3780 if (is_candidate) {
3781 _candidate_humongous++;
3782 g1h->register_humongous_region_with_cset(rindex);
3783 // Is_candidate already filters out humongous object with large remembered sets.
3784 // If we have a humongous object with a few remembered sets, we simply flush these
3785 // remembered set entries into the DCQS. That will result in automatic
3786 // re-evaluation of their remembered set entries during the following evacuation
3787 // phase.
3788 if (!r->rem_set()->is_empty()) {
3789 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3790 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3791 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3792 HeapRegionRemSetIterator hrrs(r->rem_set());
3793 size_t card_index;
3794 while (hrrs.has_next(card_index)) {
3795 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3796 // The remembered set might contain references to already freed
3797 // regions. Filter out such entries to avoid failing card table
3798 // verification.
3799 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3800 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3801 *card_ptr = CardTableModRefBS::dirty_card_val();
3802 _dcq.enqueue(card_ptr);
3803 }
3804 }
3805 }
3806 r->rem_set()->clear_locked();
3807 }
3808 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3809 }
3810 _total_humongous++;
3811
3812 return false;
3813 }
3814
3815 size_t total_humongous() const { return _total_humongous; }
3816 size_t candidate_humongous() const { return _candidate_humongous; }
3817
3818 void flush_rem_set_entries() { _dcq.flush(); }
3819 };
3820
3821 void G1CollectedHeap::register_humongous_regions_with_cset() {
3822 if (!G1EagerReclaimHumongousObjects) {
3823 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3824 return;
3825 }
3826 double time = os::elapsed_counter();
3827
3828 // Collect reclaim candidate information and register candidates with cset.
3829 RegisterHumongousWithInCSetFastTestClosure cl;
3830 heap_region_iterate(&cl);
3831
3832 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3833 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3834 cl.total_humongous(),
3835 cl.candidate_humongous());
3836 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3837
3838 // Finally flush all remembered set entries to re-check into the global DCQS.
3839 cl.flush_rem_set_entries();
3840 }
3841
3842 #ifdef ASSERT
3843 class VerifyCSetClosure: public HeapRegionClosure {
3844 public:
3845 bool doHeapRegion(HeapRegion* hr) {
3846 // Here we check that the CSet region's RSet is ready for parallel
3847 // iteration. The fields that we'll verify are only manipulated
3848 // when the region is part of a CSet and is collected. Afterwards,
3849 // we reset these fields when we clear the region's RSet (when the
3850 // region is freed) so they are ready when the region is
3851 // re-allocated. The only exception to this is if there's an
3852 // evacuation failure and instead of freeing the region we leave
3853 // it in the heap. In that case, we reset these fields during
3854 // evacuation failure handling.
3855 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3856
3857 // Here's a good place to add any other checks we'd like to
3858 // perform on CSet regions.
3859 return false;
3860 }
3861 };
3862 #endif // ASSERT
3863
3864 uint G1CollectedHeap::num_task_queues() const {
3865 return _task_queues->size();
3866 }
3867
3868 #if TASKQUEUE_STATS
3869 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3870 st->print_raw_cr("GC Task Stats");
3871 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3872 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3873 }
3874
3875 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3876 print_taskqueue_stats_hdr(st);
3877
3878 TaskQueueStats totals;
3879 const uint n = num_task_queues();
3880 for (uint i = 0; i < n; ++i) {
3881 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3882 totals += task_queue(i)->stats;
3883 }
3884 st->print_raw("tot "); totals.print(st); st->cr();
3885
3886 DEBUG_ONLY(totals.verify());
3887 }
3888
3889 void G1CollectedHeap::reset_taskqueue_stats() {
3890 const uint n = num_task_queues();
3891 for (uint i = 0; i < n; ++i) {
3892 task_queue(i)->stats.reset();
3893 }
3894 }
3895 #endif // TASKQUEUE_STATS
3896
3897 void G1CollectedHeap::log_gc_header() {
3898 if (!G1Log::fine()) {
3899 return;
3900 }
3901
3902 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3903
3904 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3905 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3906 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3907
3908 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3909 }
3910
3911 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3912 if (!G1Log::fine()) {
3913 return;
3914 }
3915
3916 if (G1Log::finer()) {
3917 if (evacuation_failed()) {
3918 gclog_or_tty->print(" (to-space exhausted)");
3919 }
3920 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3921 g1_policy()->phase_times()->note_gc_end();
3922 g1_policy()->phase_times()->print(pause_time_sec);
3923 g1_policy()->print_detailed_heap_transition();
3924 } else {
3925 if (evacuation_failed()) {
3926 gclog_or_tty->print("--");
3927 }
3928 g1_policy()->print_heap_transition();
3929 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3930 }
3931 gclog_or_tty->flush();
3932 }
3933
3934 void G1CollectedHeap::wait_for_root_region_scanning() {
3935 double scan_wait_start = os::elapsedTime();
3936 // We have to wait until the CM threads finish scanning the
3937 // root regions as it's the only way to ensure that all the
3938 // objects on them have been correctly scanned before we start
3939 // moving them during the GC.
3940 bool waited = _cm->root_regions()->wait_until_scan_finished();
3941 double wait_time_ms = 0.0;
3942 if (waited) {
3943 double scan_wait_end = os::elapsedTime();
3944 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3945 }
3946 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3947 }
3948
3949 bool
3950 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3951 assert_at_safepoint(true /* should_be_vm_thread */);
3952 guarantee(!is_gc_active(), "collection is not reentrant");
3953
3954 if (GC_locker::check_active_before_gc()) {
3955 return false;
3956 }
3957
3958 _gc_timer_stw->register_gc_start();
3959
3960 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3961
3962 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3963 ResourceMark rm;
3964
3965 wait_for_root_region_scanning();
3966
3967 G1Log::update_level();
3968 print_heap_before_gc();
3969 trace_heap_before_gc(_gc_tracer_stw);
3970
3971 verify_region_sets_optional();
3972 verify_dirty_young_regions();
3973
3974 // This call will decide whether this pause is an initial-mark
3975 // pause. If it is, during_initial_mark_pause() will return true
3976 // for the duration of this pause.
3977 g1_policy()->decide_on_conc_mark_initiation();
3978
3979 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3980 assert(!collector_state()->during_initial_mark_pause() ||
3981 collector_state()->gcs_are_young(), "sanity");
3982
3983 // We also do not allow mixed GCs during marking.
3984 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3985
3986 // Record whether this pause is an initial mark. When the current
3987 // thread has completed its logging output and it's safe to signal
3988 // the CM thread, the flag's value in the policy has been reset.
3989 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3990
3991 // Inner scope for scope based logging, timers, and stats collection
3992 {
3993 EvacuationInfo evacuation_info;
3994
3995 if (collector_state()->during_initial_mark_pause()) {
3996 // We are about to start a marking cycle, so we increment the
3997 // full collection counter.
3998 increment_old_marking_cycles_started();
3999 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4000 }
4001
4002 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4003
4004 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4005
4006 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4007 workers()->active_workers(),
4008 Threads::number_of_non_daemon_threads());
4009 workers()->set_active_workers(active_workers);
4010
4011 double pause_start_sec = os::elapsedTime();
4012 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4013 log_gc_header();
4014
4015 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4016 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4017
4018 // If the secondary_free_list is not empty, append it to the
4019 // free_list. No need to wait for the cleanup operation to finish;
4020 // the region allocation code will check the secondary_free_list
4021 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4022 // set, skip this step so that the region allocation code has to
4023 // get entries from the secondary_free_list.
4024 if (!G1StressConcRegionFreeing) {
4025 append_secondary_free_list_if_not_empty_with_lock();
4026 }
4027
4028 assert(check_young_list_well_formed(), "young list should be well formed");
4029
4030 // Don't dynamically change the number of GC threads this early. A value of
4031 // 0 is used to indicate serial work. When parallel work is done,
4032 // it will be set.
4033
4034 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4035 IsGCActiveMark x;
4036
4037 gc_prologue(false);
4038 increment_total_collections(false /* full gc */);
4039 increment_gc_time_stamp();
4040
4041 verify_before_gc();
4042
4043 check_bitmaps("GC Start");
4044
4045 #if defined(COMPILER2) || INCLUDE_JVMCI
4046 DerivedPointerTable::clear();
4047 #endif
4048
4049 // Please see comment in g1CollectedHeap.hpp and
4050 // G1CollectedHeap::ref_processing_init() to see how
4051 // reference processing currently works in G1.
4052
4053 // Enable discovery in the STW reference processor
4054 ref_processor_stw()->enable_discovery();
4055
4056 {
4057 // We want to temporarily turn off discovery by the
4058 // CM ref processor, if necessary, and turn it back on
4059 // on again later if we do. Using a scoped
4060 // NoRefDiscovery object will do this.
4061 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4062
4063 // Forget the current alloc region (we might even choose it to be part
4064 // of the collection set!).
4065 _allocator->release_mutator_alloc_region();
4066
4067 // We should call this after we retire the mutator alloc
4068 // region(s) so that all the ALLOC / RETIRE events are generated
4069 // before the start GC event.
4070 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4071
4072 // This timing is only used by the ergonomics to handle our pause target.
4073 // It is unclear why this should not include the full pause. We will
4074 // investigate this in CR 7178365.
4075 //
4076 // Preserving the old comment here if that helps the investigation:
4077 //
4078 // The elapsed time induced by the start time below deliberately elides
4079 // the possible verification above.
4080 double sample_start_time_sec = os::elapsedTime();
4081
4082 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4083
4084 if (collector_state()->during_initial_mark_pause()) {
4085 concurrent_mark()->checkpointRootsInitialPre();
4086 }
4087
4088 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
4089 g1_policy()->finalize_old_cset_part(time_remaining_ms);
4090
4091 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
4092
4093 register_humongous_regions_with_cset();
4094
4095 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4096
4097 _cm->note_start_of_gc();
4098 // We call this after finalize_cset() to
4099 // ensure that the CSet has been finalized.
4100 _cm->verify_no_cset_oops();
4101
4102 if (_hr_printer.is_active()) {
4103 HeapRegion* hr = g1_policy()->collection_set();
4104 while (hr != NULL) {
4105 _hr_printer.cset(hr);
4106 hr = hr->next_in_collection_set();
4107 }
4108 }
4109
4110 #ifdef ASSERT
4111 VerifyCSetClosure cl;
4112 collection_set_iterate(&cl);
4113 #endif // ASSERT
4114
4115 // Initialize the GC alloc regions.
4116 _allocator->init_gc_alloc_regions(evacuation_info);
4117
4118 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
4119 // Actually do the work...
4120 evacuate_collection_set(evacuation_info, &per_thread_states);
4121
4122 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
4123 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
4124
4125 eagerly_reclaim_humongous_regions();
4126
4127 g1_policy()->clear_collection_set();
4128
4129 // Start a new incremental collection set for the next pause.
4130 g1_policy()->start_incremental_cset_building();
4131
4132 clear_cset_fast_test();
4133
4134 _young_list->reset_sampled_info();
4135
4136 // Don't check the whole heap at this point as the
4137 // GC alloc regions from this pause have been tagged
4138 // as survivors and moved on to the survivor list.
4139 // Survivor regions will fail the !is_young() check.
4140 assert(check_young_list_empty(false /* check_heap */),
4141 "young list should be empty");
4142
4143 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4144 _young_list->first_survivor_region(),
4145 _young_list->last_survivor_region());
4146
4147 _young_list->reset_auxilary_lists();
4148
4149 if (evacuation_failed()) {
4150 set_used(recalculate_used());
4151 if (_archive_allocator != NULL) {
4152 _archive_allocator->clear_used();
4153 }
4154 for (uint i = 0; i < ParallelGCThreads; i++) {
4155 if (_evacuation_failed_info_array[i].has_failed()) {
4156 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4157 }
4158 }
4159 } else {
4160 // The "used" of the the collection set have already been subtracted
4161 // when they were freed. Add in the bytes evacuated.
4162 increase_used(g1_policy()->bytes_copied_during_gc());
4163 }
4164
4165 if (collector_state()->during_initial_mark_pause()) {
4166 // We have to do this before we notify the CM threads that
4167 // they can start working to make sure that all the
4168 // appropriate initialization is done on the CM object.
4169 concurrent_mark()->checkpointRootsInitialPost();
4170 collector_state()->set_mark_in_progress(true);
4171 // Note that we don't actually trigger the CM thread at
4172 // this point. We do that later when we're sure that
4173 // the current thread has completed its logging output.
4174 }
4175
4176 allocate_dummy_regions();
4177
4178 _allocator->init_mutator_alloc_region();
4179
4180 {
4181 size_t expand_bytes = g1_policy()->expansion_amount();
4182 if (expand_bytes > 0) {
4183 size_t bytes_before = capacity();
4184 // No need for an ergo verbose message here,
4185 // expansion_amount() does this when it returns a value > 0.
4186 if (!expand(expand_bytes)) {
4187 // We failed to expand the heap. Cannot do anything about it.
4188 }
4189 }
4190 }
4191
4192 // We redo the verification but now wrt to the new CSet which
4193 // has just got initialized after the previous CSet was freed.
4194 _cm->verify_no_cset_oops();
4195 _cm->note_end_of_gc();
4196
4197 // This timing is only used by the ergonomics to handle our pause target.
4198 // It is unclear why this should not include the full pause. We will
4199 // investigate this in CR 7178365.
4200 double sample_end_time_sec = os::elapsedTime();
4201 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4202 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4203 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4204
4205 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4206 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4207
4208 MemoryService::track_memory_usage();
4209
4210 // In prepare_for_verify() below we'll need to scan the deferred
4211 // update buffers to bring the RSets up-to-date if
4212 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4213 // the update buffers we'll probably need to scan cards on the
4214 // regions we just allocated to (i.e., the GC alloc
4215 // regions). However, during the last GC we called
4216 // set_saved_mark() on all the GC alloc regions, so card
4217 // scanning might skip the [saved_mark_word()...top()] area of
4218 // those regions (i.e., the area we allocated objects into
4219 // during the last GC). But it shouldn't. Given that
4220 // saved_mark_word() is conditional on whether the GC time stamp
4221 // on the region is current or not, by incrementing the GC time
4222 // stamp here we invalidate all the GC time stamps on all the
4223 // regions and saved_mark_word() will simply return top() for
4224 // all the regions. This is a nicer way of ensuring this rather
4225 // than iterating over the regions and fixing them. In fact, the
4226 // GC time stamp increment here also ensures that
4227 // saved_mark_word() will return top() between pauses, i.e.,
4228 // during concurrent refinement. So we don't need the
4229 // is_gc_active() check to decided which top to use when
4230 // scanning cards (see CR 7039627).
4231 increment_gc_time_stamp();
4232
4233 verify_after_gc();
4234 check_bitmaps("GC End");
4235
4236 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4237 ref_processor_stw()->verify_no_references_recorded();
4238
4239 // CM reference discovery will be re-enabled if necessary.
4240 }
4241
4242 // We should do this after we potentially expand the heap so
4243 // that all the COMMIT events are generated before the end GC
4244 // event, and after we retire the GC alloc regions so that all
4245 // RETIRE events are generated before the end GC event.
4246 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4247
4248 #ifdef TRACESPINNING
4249 ParallelTaskTerminator::print_termination_counts();
4250 #endif
4251
4252 gc_epilogue(false);
4253 }
4254
4255 // Print the remainder of the GC log output.
4256 log_gc_footer(os::elapsedTime() - pause_start_sec);
4257
4258 // It is not yet to safe to tell the concurrent mark to
4259 // start as we have some optional output below. We don't want the
4260 // output from the concurrent mark thread interfering with this
4261 // logging output either.
4262
4263 _hrm.verify_optional();
4264 verify_region_sets_optional();
4265
4266 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4267 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4268
4269 print_heap_after_gc();
4270 trace_heap_after_gc(_gc_tracer_stw);
4271
4272 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4273 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4274 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4275 // before any GC notifications are raised.
4276 g1mm()->update_sizes();
4277
4278 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4279 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4280 _gc_timer_stw->register_gc_end();
4281 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4282 }
4283 // It should now be safe to tell the concurrent mark thread to start
4284 // without its logging output interfering with the logging output
4285 // that came from the pause.
4286
4287 if (should_start_conc_mark) {
4288 // CAUTION: after the doConcurrentMark() call below,
4289 // the concurrent marking thread(s) could be running
4290 // concurrently with us. Make sure that anything after
4291 // this point does not assume that we are the only GC thread
4292 // running. Note: of course, the actual marking work will
4293 // not start until the safepoint itself is released in
4294 // SuspendibleThreadSet::desynchronize().
4295 doConcurrentMark();
4296 }
4297
4298 return true;
4299 }
4300
4301 void G1CollectedHeap::remove_self_forwarding_pointers() {
4302 double remove_self_forwards_start = os::elapsedTime();
4303
4304 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4305 workers()->run_task(&rsfp_task);
4306
4307 // Now restore saved marks, if any.
4308 for (uint i = 0; i < ParallelGCThreads; i++) {
4309 OopAndMarkOopStack& cur = _preserved_objs[i];
4310 while (!cur.is_empty()) {
4311 OopAndMarkOop elem = cur.pop();
4312 elem.set_mark();
4313 }
4314 cur.clear(true);
4315 }
4316
4317 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4318 }
4319
4320 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4321 if (!_evacuation_failed) {
4322 _evacuation_failed = true;
4323 }
4324
4325 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4326
4327 // We want to call the "for_promotion_failure" version only in the
4328 // case of a promotion failure.
4329 if (m->must_be_preserved_for_promotion_failure(obj)) {
4330 OopAndMarkOop elem(obj, m);
4331 _preserved_objs[worker_id].push(elem);
4332 }
4333 }
4334
4335 void G1ParCopyHelper::mark_object(oop obj) {
4336 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4337
4338 // We know that the object is not moving so it's safe to read its size.
4339 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4340 }
4341
4342 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4343 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4344 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4345 assert(from_obj != to_obj, "should not be self-forwarded");
4346
4347 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4348 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4349
4350 // The object might be in the process of being copied by another
4351 // worker so we cannot trust that its to-space image is
4352 // well-formed. So we have to read its size from its from-space
4353 // image which we know should not be changing.
4354 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4355 }
4356
4357 template <class T>
4358 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4359 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4360 _scanned_klass->record_modified_oops();
4361 }
4362 }
4363
4364 template <G1Barrier barrier, G1Mark do_mark_object>
4365 template <class T>
4366 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4367 T heap_oop = oopDesc::load_heap_oop(p);
4368
4369 if (oopDesc::is_null(heap_oop)) {
4370 return;
4371 }
4372
4373 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4374
4375 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4376
4377 const InCSetState state = _g1->in_cset_state(obj);
4378 if (state.is_in_cset()) {
4379 oop forwardee;
4380 markOop m = obj->mark();
4381 if (m->is_marked()) {
4382 forwardee = (oop) m->decode_pointer();
4383 } else {
4384 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4385 }
4386 assert(forwardee != NULL, "forwardee should not be NULL");
4387 oopDesc::encode_store_heap_oop(p, forwardee);
4388 if (do_mark_object != G1MarkNone && forwardee != obj) {
4389 // If the object is self-forwarded we don't need to explicitly
4390 // mark it, the evacuation failure protocol will do so.
4391 mark_forwarded_object(obj, forwardee);
4392 }
4393
4394 if (barrier == G1BarrierKlass) {
4395 do_klass_barrier(p, forwardee);
4396 }
4397 } else {
4398 if (state.is_humongous()) {
4399 _g1->set_humongous_is_live(obj);
4400 }
4401 // The object is not in collection set. If we're a root scanning
4402 // closure during an initial mark pause then attempt to mark the object.
4403 if (do_mark_object == G1MarkFromRoot) {
4404 mark_object(obj);
4405 }
4406 }
4407 }
4408
4409 class G1ParEvacuateFollowersClosure : public VoidClosure {
4410 private:
4411 double _start_term;
4412 double _term_time;
4413 size_t _term_attempts;
4414
4415 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4416 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4417 protected:
4418 G1CollectedHeap* _g1h;
4419 G1ParScanThreadState* _par_scan_state;
4420 RefToScanQueueSet* _queues;
4421 ParallelTaskTerminator* _terminator;
4422
4423 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4424 RefToScanQueueSet* queues() { return _queues; }
4425 ParallelTaskTerminator* terminator() { return _terminator; }
4426
4427 public:
4428 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4429 G1ParScanThreadState* par_scan_state,
4430 RefToScanQueueSet* queues,
4431 ParallelTaskTerminator* terminator)
4432 : _g1h(g1h), _par_scan_state(par_scan_state),
4433 _queues(queues), _terminator(terminator),
4434 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4435
4436 void do_void();
4437
4438 double term_time() const { return _term_time; }
4439 size_t term_attempts() const { return _term_attempts; }
4440
4441 private:
4442 inline bool offer_termination();
4443 };
4444
4445 bool G1ParEvacuateFollowersClosure::offer_termination() {
4446 G1ParScanThreadState* const pss = par_scan_state();
4447 start_term_time();
4448 const bool res = terminator()->offer_termination();
4449 end_term_time();
4450 return res;
4451 }
4452
4453 void G1ParEvacuateFollowersClosure::do_void() {
4454 G1ParScanThreadState* const pss = par_scan_state();
4455 pss->trim_queue();
4456 do {
4457 pss->steal_and_trim_queue(queues());
4458 } while (!offer_termination());
4459 }
4460
4461 class G1KlassScanClosure : public KlassClosure {
4462 G1ParCopyHelper* _closure;
4463 bool _process_only_dirty;
4464 int _count;
4465 public:
4466 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4467 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4468 void do_klass(Klass* klass) {
4469 // If the klass has not been dirtied we know that there's
4470 // no references into the young gen and we can skip it.
4471 if (!_process_only_dirty || klass->has_modified_oops()) {
4472 // Clean the klass since we're going to scavenge all the metadata.
4473 klass->clear_modified_oops();
4474
4475 // Tell the closure that this klass is the Klass to scavenge
4476 // and is the one to dirty if oops are left pointing into the young gen.
4477 _closure->set_scanned_klass(klass);
4478
4479 klass->oops_do(_closure);
4480
4481 _closure->set_scanned_klass(NULL);
4482 }
4483 _count++;
4484 }
4485 };
4486
4487 class G1ParTask : public AbstractGangTask {
4488 protected:
4489 G1CollectedHeap* _g1h;
4490 G1ParScanThreadStateSet* _pss;
4491 RefToScanQueueSet* _queues;
4492 G1RootProcessor* _root_processor;
4493 ParallelTaskTerminator _terminator;
4494 uint _n_workers;
4495
4496 public:
4497 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4498 : AbstractGangTask("G1 collection"),
4499 _g1h(g1h),
4500 _pss(per_thread_states),
4501 _queues(task_queues),
4502 _root_processor(root_processor),
4503 _terminator(n_workers, _queues),
4504 _n_workers(n_workers)
4505 {}
4506
4507 RefToScanQueueSet* queues() { return _queues; }
4508
4509 RefToScanQueue *work_queue(int i) {
4510 return queues()->queue(i);
4511 }
4512
4513 ParallelTaskTerminator* terminator() { return &_terminator; }
4514
4515 // Helps out with CLD processing.
4516 //
4517 // During InitialMark we need to:
4518 // 1) Scavenge all CLDs for the young GC.
4519 // 2) Mark all objects directly reachable from strong CLDs.
4520 template <G1Mark do_mark_object>
4521 class G1CLDClosure : public CLDClosure {
4522 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4523 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4524 G1KlassScanClosure _klass_in_cld_closure;
4525 bool _claim;
4526
4527 public:
4528 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4529 bool only_young, bool claim)
4530 : _oop_closure(oop_closure),
4531 _oop_in_klass_closure(oop_closure->g1(),
4532 oop_closure->pss()),
4533 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4534 _claim(claim) {
4535
4536 }
4537
4538 void do_cld(ClassLoaderData* cld) {
4539 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4540 }
4541 };
4542
4543 void work(uint worker_id) {
4544 if (worker_id >= _n_workers) return; // no work needed this round
4545
4546 double start_sec = os::elapsedTime();
4547 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4548
4549 {
4550 ResourceMark rm;
4551 HandleMark hm;
4552
4553 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4554
4555 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4556 pss->set_ref_processor(rp);
4557
4558 bool only_young = _g1h->collector_state()->gcs_are_young();
4559
4560 // Non-IM young GC.
4561 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, pss);
4562 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4563 only_young, // Only process dirty klasses.
4564 false); // No need to claim CLDs.
4565 // IM young GC.
4566 // Strong roots closures.
4567 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, pss);
4568 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4569 false, // Process all klasses.
4570 true); // Need to claim CLDs.
4571 // Weak roots closures.
4572 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, pss);
4573 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4574 false, // Process all klasses.
4575 true); // Need to claim CLDs.
4576
4577 OopClosure* strong_root_cl;
4578 OopClosure* weak_root_cl;
4579 CLDClosure* strong_cld_cl;
4580 CLDClosure* weak_cld_cl;
4581
4582 bool trace_metadata = false;
4583
4584 if (_g1h->collector_state()->during_initial_mark_pause()) {
4585 // We also need to mark copied objects.
4586 strong_root_cl = &scan_mark_root_cl;
4587 strong_cld_cl = &scan_mark_cld_cl;
4588 if (ClassUnloadingWithConcurrentMark) {
4589 weak_root_cl = &scan_mark_weak_root_cl;
4590 weak_cld_cl = &scan_mark_weak_cld_cl;
4591 trace_metadata = true;
4592 } else {
4593 weak_root_cl = &scan_mark_root_cl;
4594 weak_cld_cl = &scan_mark_cld_cl;
4595 }
4596 } else {
4597 strong_root_cl = &scan_only_root_cl;
4598 weak_root_cl = &scan_only_root_cl;
4599 strong_cld_cl = &scan_only_cld_cl;
4600 weak_cld_cl = &scan_only_cld_cl;
4601 }
4602
4603 double start_strong_roots_sec = os::elapsedTime();
4604 _root_processor->evacuate_roots(strong_root_cl,
4605 weak_root_cl,
4606 strong_cld_cl,
4607 weak_cld_cl,
4608 trace_metadata,
4609 worker_id);
4610
4611 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4612 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4613 weak_root_cl,
4614 worker_id);
4615
4616 _pss->add_cards_scanned(worker_id, cards_scanned);
4617
4618 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4619
4620 double term_sec = 0.0;
4621 size_t evac_term_attempts = 0;
4622 {
4623 double start = os::elapsedTime();
4624 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4625 evac.do_void();
4626
4627 evac_term_attempts = evac.term_attempts();
4628 term_sec = evac.term_time();
4629 double elapsed_sec = os::elapsedTime() - start;
4630 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4631 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4632 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4633 }
4634
4635 assert(pss->queue_is_empty(), "should be empty");
4636
4637 if (PrintTerminationStats) {
4638 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4639 size_t lab_waste;
4640 size_t lab_undo_waste;
4641 pss->waste(lab_waste, lab_undo_waste);
4642 _g1h->print_termination_stats(gclog_or_tty,
4643 worker_id,
4644 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4645 strong_roots_sec * 1000.0, /* strong roots time */
4646 term_sec * 1000.0, /* evac term time */
4647 evac_term_attempts, /* evac term attempts */
4648 lab_waste, /* alloc buffer waste */
4649 lab_undo_waste /* undo waste */
4650 );
4651 }
4652
4653 // Close the inner scope so that the ResourceMark and HandleMark
4654 // destructors are executed here and are included as part of the
4655 // "GC Worker Time".
4656 }
4657 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4658 }
4659 };
4660
4661 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4662 st->print_raw_cr("GC Termination Stats");
4663 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4664 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4665 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4666 }
4667
4668 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4669 uint worker_id,
4670 double elapsed_ms,
4671 double strong_roots_ms,
4672 double term_ms,
4673 size_t term_attempts,
4674 size_t alloc_buffer_waste,
4675 size_t undo_waste) const {
4676 st->print_cr("%3d %9.2f %9.2f %6.2f "
4677 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4678 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4679 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4680 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4681 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4682 alloc_buffer_waste * HeapWordSize / K,
4683 undo_waste * HeapWordSize / K);
4684 }
4685
4686 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4687 private:
4688 BoolObjectClosure* _is_alive;
4689 int _initial_string_table_size;
4690 int _initial_symbol_table_size;
4691
4692 bool _process_strings;
4693 int _strings_processed;
4694 int _strings_removed;
4695
4696 bool _process_symbols;
4697 int _symbols_processed;
4698 int _symbols_removed;
4699
4700 public:
4701 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4702 AbstractGangTask("String/Symbol Unlinking"),
4703 _is_alive(is_alive),
4704 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4705 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4706
4707 _initial_string_table_size = StringTable::the_table()->table_size();
4708 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4709 if (process_strings) {
4710 StringTable::clear_parallel_claimed_index();
4711 }
4712 if (process_symbols) {
4713 SymbolTable::clear_parallel_claimed_index();
4714 }
4715 }
4716
4717 ~G1StringSymbolTableUnlinkTask() {
4718 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4719 err_msg("claim value %d after unlink less than initial string table size %d",
4720 StringTable::parallel_claimed_index(), _initial_string_table_size));
4721 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4722 err_msg("claim value %d after unlink less than initial symbol table size %d",
4723 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4724
4725 if (G1TraceStringSymbolTableScrubbing) {
4726 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4727 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4728 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4729 strings_processed(), strings_removed(),
4730 symbols_processed(), symbols_removed());
4731 }
4732 }
4733
4734 void work(uint worker_id) {
4735 int strings_processed = 0;
4736 int strings_removed = 0;
4737 int symbols_processed = 0;
4738 int symbols_removed = 0;
4739 if (_process_strings) {
4740 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4741 Atomic::add(strings_processed, &_strings_processed);
4742 Atomic::add(strings_removed, &_strings_removed);
4743 }
4744 if (_process_symbols) {
4745 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4746 Atomic::add(symbols_processed, &_symbols_processed);
4747 Atomic::add(symbols_removed, &_symbols_removed);
4748 }
4749 }
4750
4751 size_t strings_processed() const { return (size_t)_strings_processed; }
4752 size_t strings_removed() const { return (size_t)_strings_removed; }
4753
4754 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4755 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4756 };
4757
4758 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4759 private:
4760 static Monitor* _lock;
4761
4762 BoolObjectClosure* const _is_alive;
4763 const bool _unloading_occurred;
4764 const uint _num_workers;
4765
4766 // Variables used to claim nmethods.
4767 nmethod* _first_nmethod;
4768 volatile nmethod* _claimed_nmethod;
4769
4770 // The list of nmethods that need to be processed by the second pass.
4771 volatile nmethod* _postponed_list;
4772 volatile uint _num_entered_barrier;
4773
4774 public:
4775 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4776 _is_alive(is_alive),
4777 _unloading_occurred(unloading_occurred),
4778 _num_workers(num_workers),
4779 _first_nmethod(NULL),
4780 _claimed_nmethod(NULL),
4781 _postponed_list(NULL),
4782 _num_entered_barrier(0)
4783 {
4784 nmethod::increase_unloading_clock();
4785 // Get first alive nmethod
4786 NMethodIterator iter = NMethodIterator();
4787 if(iter.next_alive()) {
4788 _first_nmethod = iter.method();
4789 }
4790 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4791 }
4792
4793 ~G1CodeCacheUnloadingTask() {
4794 CodeCache::verify_clean_inline_caches();
4795
4796 CodeCache::set_needs_cache_clean(false);
4797 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4798
4799 CodeCache::verify_icholder_relocations();
4800 }
4801
4802 private:
4803 void add_to_postponed_list(nmethod* nm) {
4804 nmethod* old;
4805 do {
4806 old = (nmethod*)_postponed_list;
4807 nm->set_unloading_next(old);
4808 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4809 }
4810
4811 void clean_nmethod(nmethod* nm) {
4812 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4813
4814 if (postponed) {
4815 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4816 add_to_postponed_list(nm);
4817 }
4818
4819 // Mark that this thread has been cleaned/unloaded.
4820 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4821 nm->set_unloading_clock(nmethod::global_unloading_clock());
4822 }
4823
4824 void clean_nmethod_postponed(nmethod* nm) {
4825 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4826 }
4827
4828 static const int MaxClaimNmethods = 16;
4829
4830 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4831 nmethod* first;
4832 NMethodIterator last;
4833
4834 do {
4835 *num_claimed_nmethods = 0;
4836
4837 first = (nmethod*)_claimed_nmethod;
4838 last = NMethodIterator(first);
4839
4840 if (first != NULL) {
4841
4842 for (int i = 0; i < MaxClaimNmethods; i++) {
4843 if (!last.next_alive()) {
4844 break;
4845 }
4846 claimed_nmethods[i] = last.method();
4847 (*num_claimed_nmethods)++;
4848 }
4849 }
4850
4851 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4852 }
4853
4854 nmethod* claim_postponed_nmethod() {
4855 nmethod* claim;
4856 nmethod* next;
4857
4858 do {
4859 claim = (nmethod*)_postponed_list;
4860 if (claim == NULL) {
4861 return NULL;
4862 }
4863
4864 next = claim->unloading_next();
4865
4866 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4867
4868 return claim;
4869 }
4870
4871 public:
4872 // Mark that we're done with the first pass of nmethod cleaning.
4873 void barrier_mark(uint worker_id) {
4874 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4875 _num_entered_barrier++;
4876 if (_num_entered_barrier == _num_workers) {
4877 ml.notify_all();
4878 }
4879 }
4880
4881 // See if we have to wait for the other workers to
4882 // finish their first-pass nmethod cleaning work.
4883 void barrier_wait(uint worker_id) {
4884 if (_num_entered_barrier < _num_workers) {
4885 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4886 while (_num_entered_barrier < _num_workers) {
4887 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4888 }
4889 }
4890 }
4891
4892 // Cleaning and unloading of nmethods. Some work has to be postponed
4893 // to the second pass, when we know which nmethods survive.
4894 void work_first_pass(uint worker_id) {
4895 // The first nmethods is claimed by the first worker.
4896 if (worker_id == 0 && _first_nmethod != NULL) {
4897 clean_nmethod(_first_nmethod);
4898 _first_nmethod = NULL;
4899 }
4900
4901 int num_claimed_nmethods;
4902 nmethod* claimed_nmethods[MaxClaimNmethods];
4903
4904 while (true) {
4905 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4906
4907 if (num_claimed_nmethods == 0) {
4908 break;
4909 }
4910
4911 for (int i = 0; i < num_claimed_nmethods; i++) {
4912 clean_nmethod(claimed_nmethods[i]);
4913 }
4914 }
4915 }
4916
4917 void work_second_pass(uint worker_id) {
4918 nmethod* nm;
4919 // Take care of postponed nmethods.
4920 while ((nm = claim_postponed_nmethod()) != NULL) {
4921 clean_nmethod_postponed(nm);
4922 }
4923 }
4924 };
4925
4926 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4927
4928 class G1KlassCleaningTask : public StackObj {
4929 BoolObjectClosure* _is_alive;
4930 volatile jint _clean_klass_tree_claimed;
4931 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4932
4933 public:
4934 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4935 _is_alive(is_alive),
4936 _clean_klass_tree_claimed(0),
4937 _klass_iterator() {
4938 }
4939
4940 private:
4941 bool claim_clean_klass_tree_task() {
4942 if (_clean_klass_tree_claimed) {
4943 return false;
4944 }
4945
4946 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4947 }
4948
4949 InstanceKlass* claim_next_klass() {
4950 Klass* klass;
4951 do {
4952 klass =_klass_iterator.next_klass();
4953 } while (klass != NULL && !klass->oop_is_instance());
4954
4955 return (InstanceKlass*)klass;
4956 }
4957
4958 public:
4959
4960 void clean_klass(InstanceKlass* ik) {
4961 ik->clean_implementors_list(_is_alive);
4962 ik->clean_method_data(_is_alive);
4963
4964 // G1 specific cleanup work that has
4965 // been moved here to be done in parallel.
4966 ik->clean_dependent_nmethods();
4967 }
4968
4969 void work() {
4970 ResourceMark rm;
4971
4972 // One worker will clean the subklass/sibling klass tree.
4973 if (claim_clean_klass_tree_task()) {
4974 Klass::clean_subklass_tree(_is_alive);
4975 }
4976
4977 // All workers will help cleaning the classes,
4978 InstanceKlass* klass;
4979 while ((klass = claim_next_klass()) != NULL) {
4980 clean_klass(klass);
4981 }
4982 }
4983 };
4984
4985 // To minimize the remark pause times, the tasks below are done in parallel.
4986 class G1ParallelCleaningTask : public AbstractGangTask {
4987 private:
4988 G1StringSymbolTableUnlinkTask _string_symbol_task;
4989 G1CodeCacheUnloadingTask _code_cache_task;
4990 G1KlassCleaningTask _klass_cleaning_task;
4991
4992 public:
4993 // The constructor is run in the VMThread.
4994 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4995 AbstractGangTask("Parallel Cleaning"),
4996 _string_symbol_task(is_alive, process_strings, process_symbols),
4997 _code_cache_task(num_workers, is_alive, unloading_occurred),
4998 _klass_cleaning_task(is_alive) {
4999 }
5000
5001 // The parallel work done by all worker threads.
5002 void work(uint worker_id) {
5003 // Do first pass of code cache cleaning.
5004 _code_cache_task.work_first_pass(worker_id);
5005
5006 // Let the threads mark that the first pass is done.
5007 _code_cache_task.barrier_mark(worker_id);
5008
5009 // Clean the Strings and Symbols.
5010 _string_symbol_task.work(worker_id);
5011
5012 // Wait for all workers to finish the first code cache cleaning pass.
5013 _code_cache_task.barrier_wait(worker_id);
5014
5015 // Do the second code cache cleaning work, which realize on
5016 // the liveness information gathered during the first pass.
5017 _code_cache_task.work_second_pass(worker_id);
5018
5019 // Clean all klasses that were not unloaded.
5020 _klass_cleaning_task.work();
5021 }
5022 };
5023
5024
5025 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5026 bool process_strings,
5027 bool process_symbols,
5028 bool class_unloading_occurred) {
5029 uint n_workers = workers()->active_workers();
5030
5031 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5032 n_workers, class_unloading_occurred);
5033 workers()->run_task(&g1_unlink_task);
5034 }
5035
5036 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5037 bool process_strings, bool process_symbols) {
5038 {
5039 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5040 workers()->run_task(&g1_unlink_task);
5041 }
5042
5043 if (G1StringDedup::is_enabled()) {
5044 G1StringDedup::unlink(is_alive);
5045 }
5046 }
5047
5048 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5049 private:
5050 DirtyCardQueueSet* _queue;
5051 public:
5052 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5053
5054 virtual void work(uint worker_id) {
5055 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5056 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5057
5058 RedirtyLoggedCardTableEntryClosure cl;
5059 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5060
5061 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5062 }
5063 };
5064
5065 void G1CollectedHeap::redirty_logged_cards() {
5066 double redirty_logged_cards_start = os::elapsedTime();
5067
5068 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5069 dirty_card_queue_set().reset_for_par_iteration();
5070 workers()->run_task(&redirty_task);
5071
5072 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5073 dcq.merge_bufferlists(&dirty_card_queue_set());
5074 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5075
5076 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5077 }
5078
5079 // Weak Reference Processing support
5080
5081 // An always "is_alive" closure that is used to preserve referents.
5082 // If the object is non-null then it's alive. Used in the preservation
5083 // of referent objects that are pointed to by reference objects
5084 // discovered by the CM ref processor.
5085 class G1AlwaysAliveClosure: public BoolObjectClosure {
5086 G1CollectedHeap* _g1;
5087 public:
5088 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5089 bool do_object_b(oop p) {
5090 if (p != NULL) {
5091 return true;
5092 }
5093 return false;
5094 }
5095 };
5096
5097 bool G1STWIsAliveClosure::do_object_b(oop p) {
5098 // An object is reachable if it is outside the collection set,
5099 // or is inside and copied.
5100 return !_g1->is_in_cset(p) || p->is_forwarded();
5101 }
5102
5103 // Non Copying Keep Alive closure
5104 class G1KeepAliveClosure: public OopClosure {
5105 G1CollectedHeap* _g1;
5106 public:
5107 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5108 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5109 void do_oop(oop* p) {
5110 oop obj = *p;
5111 assert(obj != NULL, "the caller should have filtered out NULL values");
5112
5113 const InCSetState cset_state = _g1->in_cset_state(obj);
5114 if (!cset_state.is_in_cset_or_humongous()) {
5115 return;
5116 }
5117 if (cset_state.is_in_cset()) {
5118 assert( obj->is_forwarded(), "invariant" );
5119 *p = obj->forwardee();
5120 } else {
5121 assert(!obj->is_forwarded(), "invariant" );
5122 assert(cset_state.is_humongous(),
5123 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5124 _g1->set_humongous_is_live(obj);
5125 }
5126 }
5127 };
5128
5129 // Copying Keep Alive closure - can be called from both
5130 // serial and parallel code as long as different worker
5131 // threads utilize different G1ParScanThreadState instances
5132 // and different queues.
5133
5134 class G1CopyingKeepAliveClosure: public OopClosure {
5135 G1CollectedHeap* _g1h;
5136 OopClosure* _copy_non_heap_obj_cl;
5137 G1ParScanThreadState* _par_scan_state;
5138
5139 public:
5140 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5141 OopClosure* non_heap_obj_cl,
5142 G1ParScanThreadState* pss):
5143 _g1h(g1h),
5144 _copy_non_heap_obj_cl(non_heap_obj_cl),
5145 _par_scan_state(pss)
5146 {}
5147
5148 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5149 virtual void do_oop( oop* p) { do_oop_work(p); }
5150
5151 template <class T> void do_oop_work(T* p) {
5152 oop obj = oopDesc::load_decode_heap_oop(p);
5153
5154 if (_g1h->is_in_cset_or_humongous(obj)) {
5155 // If the referent object has been forwarded (either copied
5156 // to a new location or to itself in the event of an
5157 // evacuation failure) then we need to update the reference
5158 // field and, if both reference and referent are in the G1
5159 // heap, update the RSet for the referent.
5160 //
5161 // If the referent has not been forwarded then we have to keep
5162 // it alive by policy. Therefore we have copy the referent.
5163 //
5164 // If the reference field is in the G1 heap then we can push
5165 // on the PSS queue. When the queue is drained (after each
5166 // phase of reference processing) the object and it's followers
5167 // will be copied, the reference field set to point to the
5168 // new location, and the RSet updated. Otherwise we need to
5169 // use the the non-heap or metadata closures directly to copy
5170 // the referent object and update the pointer, while avoiding
5171 // updating the RSet.
5172
5173 if (_g1h->is_in_g1_reserved(p)) {
5174 _par_scan_state->push_on_queue(p);
5175 } else {
5176 assert(!Metaspace::contains((const void*)p),
5177 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5178 _copy_non_heap_obj_cl->do_oop(p);
5179 }
5180 }
5181 }
5182 };
5183
5184 // Serial drain queue closure. Called as the 'complete_gc'
5185 // closure for each discovered list in some of the
5186 // reference processing phases.
5187
5188 class G1STWDrainQueueClosure: public VoidClosure {
5189 protected:
5190 G1CollectedHeap* _g1h;
5191 G1ParScanThreadState* _par_scan_state;
5192
5193 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5194
5195 public:
5196 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5197 _g1h(g1h),
5198 _par_scan_state(pss)
5199 { }
5200
5201 void do_void() {
5202 G1ParScanThreadState* const pss = par_scan_state();
5203 pss->trim_queue();
5204 }
5205 };
5206
5207 // Parallel Reference Processing closures
5208
5209 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5210 // processing during G1 evacuation pauses.
5211
5212 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5213 private:
5214 G1CollectedHeap* _g1h;
5215 G1ParScanThreadStateSet* _pss;
5216 RefToScanQueueSet* _queues;
5217 WorkGang* _workers;
5218 uint _active_workers;
5219
5220 public:
5221 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5222 G1ParScanThreadStateSet* per_thread_states,
5223 WorkGang* workers,
5224 RefToScanQueueSet *task_queues,
5225 uint n_workers) :
5226 _g1h(g1h),
5227 _pss(per_thread_states),
5228 _queues(task_queues),
5229 _workers(workers),
5230 _active_workers(n_workers)
5231 {
5232 assert(n_workers > 0, "shouldn't call this otherwise");
5233 }
5234
5235 // Executes the given task using concurrent marking worker threads.
5236 virtual void execute(ProcessTask& task);
5237 virtual void execute(EnqueueTask& task);
5238 };
5239
5240 // Gang task for possibly parallel reference processing
5241
5242 class G1STWRefProcTaskProxy: public AbstractGangTask {
5243 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5244 ProcessTask& _proc_task;
5245 G1CollectedHeap* _g1h;
5246 G1ParScanThreadStateSet* _pss;
5247 RefToScanQueueSet* _task_queues;
5248 ParallelTaskTerminator* _terminator;
5249
5250 public:
5251 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5252 G1CollectedHeap* g1h,
5253 G1ParScanThreadStateSet* per_thread_states,
5254 RefToScanQueueSet *task_queues,
5255 ParallelTaskTerminator* terminator) :
5256 AbstractGangTask("Process reference objects in parallel"),
5257 _proc_task(proc_task),
5258 _g1h(g1h),
5259 _pss(per_thread_states),
5260 _task_queues(task_queues),
5261 _terminator(terminator)
5262 {}
5263
5264 virtual void work(uint worker_id) {
5265 // The reference processing task executed by a single worker.
5266 ResourceMark rm;
5267 HandleMark hm;
5268
5269 G1STWIsAliveClosure is_alive(_g1h);
5270
5271 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5272 pss->set_ref_processor(NULL);
5273
5274 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5275
5276 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5277
5278 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5279
5280 if (_g1h->collector_state()->during_initial_mark_pause()) {
5281 // We also need to mark copied objects.
5282 copy_non_heap_cl = ©_mark_non_heap_cl;
5283 }
5284
5285 // Keep alive closure.
5286 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5287
5288 // Complete GC closure
5289 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
5290
5291 // Call the reference processing task's work routine.
5292 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5293
5294 // Note we cannot assert that the refs array is empty here as not all
5295 // of the processing tasks (specifically phase2 - pp2_work) execute
5296 // the complete_gc closure (which ordinarily would drain the queue) so
5297 // the queue may not be empty.
5298 }
5299 };
5300
5301 // Driver routine for parallel reference processing.
5302 // Creates an instance of the ref processing gang
5303 // task and has the worker threads execute it.
5304 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5305 assert(_workers != NULL, "Need parallel worker threads.");
5306
5307 ParallelTaskTerminator terminator(_active_workers, _queues);
5308 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
5309
5310 _workers->run_task(&proc_task_proxy);
5311 }
5312
5313 // Gang task for parallel reference enqueueing.
5314
5315 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5316 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5317 EnqueueTask& _enq_task;
5318
5319 public:
5320 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5321 AbstractGangTask("Enqueue reference objects in parallel"),
5322 _enq_task(enq_task)
5323 { }
5324
5325 virtual void work(uint worker_id) {
5326 _enq_task.work(worker_id);
5327 }
5328 };
5329
5330 // Driver routine for parallel reference enqueueing.
5331 // Creates an instance of the ref enqueueing gang
5332 // task and has the worker threads execute it.
5333
5334 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5335 assert(_workers != NULL, "Need parallel worker threads.");
5336
5337 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5338
5339 _workers->run_task(&enq_task_proxy);
5340 }
5341
5342 // End of weak reference support closures
5343
5344 // Abstract task used to preserve (i.e. copy) any referent objects
5345 // that are in the collection set and are pointed to by reference
5346 // objects discovered by the CM ref processor.
5347
5348 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5349 protected:
5350 G1CollectedHeap* _g1h;
5351 G1ParScanThreadStateSet* _pss;
5352 RefToScanQueueSet* _queues;
5353 ParallelTaskTerminator _terminator;
5354 uint _n_workers;
5355
5356 public:
5357 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
5358 AbstractGangTask("ParPreserveCMReferents"),
5359 _g1h(g1h),
5360 _pss(per_thread_states),
5361 _queues(task_queues),
5362 _terminator(workers, _queues),
5363 _n_workers(workers)
5364 { }
5365
5366 void work(uint worker_id) {
5367 ResourceMark rm;
5368 HandleMark hm;
5369
5370 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
5371 pss->set_ref_processor(NULL);
5372 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5373
5374 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, pss);
5375
5376 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, pss);
5377
5378 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5379
5380 if (_g1h->collector_state()->during_initial_mark_pause()) {
5381 // We also need to mark copied objects.
5382 copy_non_heap_cl = ©_mark_non_heap_cl;
5383 }
5384
5385 // Is alive closure
5386 G1AlwaysAliveClosure always_alive(_g1h);
5387
5388 // Copying keep alive closure. Applied to referent objects that need
5389 // to be copied.
5390 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, pss);
5391
5392 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5393
5394 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5395 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5396
5397 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5398 // So this must be true - but assert just in case someone decides to
5399 // change the worker ids.
5400 assert(worker_id < limit, "sanity");
5401 assert(!rp->discovery_is_atomic(), "check this code");
5402
5403 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5404 for (uint idx = worker_id; idx < limit; idx += stride) {
5405 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5406
5407 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5408 while (iter.has_next()) {
5409 // Since discovery is not atomic for the CM ref processor, we
5410 // can see some null referent objects.
5411 iter.load_ptrs(DEBUG_ONLY(true));
5412 oop ref = iter.obj();
5413
5414 // This will filter nulls.
5415 if (iter.is_referent_alive()) {
5416 iter.make_referent_alive();
5417 }
5418 iter.move_to_next();
5419 }
5420 }
5421
5422 // Drain the queue - which may cause stealing
5423 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5424 drain_queue.do_void();
5425 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5426 assert(pss->queue_is_empty(), "should be");
5427 }
5428 };
5429
5430 // Weak Reference processing during an evacuation pause (part 1).
5431 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5432 double ref_proc_start = os::elapsedTime();
5433
5434 ReferenceProcessor* rp = _ref_processor_stw;
5435 assert(rp->discovery_enabled(), "should have been enabled");
5436
5437 // Any reference objects, in the collection set, that were 'discovered'
5438 // by the CM ref processor should have already been copied (either by
5439 // applying the external root copy closure to the discovered lists, or
5440 // by following an RSet entry).
5441 //
5442 // But some of the referents, that are in the collection set, that these
5443 // reference objects point to may not have been copied: the STW ref
5444 // processor would have seen that the reference object had already
5445 // been 'discovered' and would have skipped discovering the reference,
5446 // but would not have treated the reference object as a regular oop.
5447 // As a result the copy closure would not have been applied to the
5448 // referent object.
5449 //
5450 // We need to explicitly copy these referent objects - the references
5451 // will be processed at the end of remarking.
5452 //
5453 // We also need to do this copying before we process the reference
5454 // objects discovered by the STW ref processor in case one of these
5455 // referents points to another object which is also referenced by an
5456 // object discovered by the STW ref processor.
5457
5458 uint no_of_gc_workers = workers()->active_workers();
5459
5460 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5461 per_thread_states,
5462 no_of_gc_workers,
5463 _task_queues);
5464
5465 workers()->run_task(&keep_cm_referents);
5466
5467 // Closure to test whether a referent is alive.
5468 G1STWIsAliveClosure is_alive(this);
5469
5470 // Even when parallel reference processing is enabled, the processing
5471 // of JNI refs is serial and performed serially by the current thread
5472 // rather than by a worker. The following PSS will be used for processing
5473 // JNI refs.
5474
5475 // Use only a single queue for this PSS.
5476 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5477 pss->set_ref_processor(NULL);
5478 assert(pss->queue_is_empty(), "pre-condition");
5479
5480 // We do not embed a reference processor in the copying/scanning
5481 // closures while we're actually processing the discovered
5482 // reference objects.
5483
5484 G1ParScanExtRootClosure only_copy_non_heap_cl(this, pss);
5485
5486 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, pss);
5487
5488 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5489
5490 if (collector_state()->during_initial_mark_pause()) {
5491 // We also need to mark copied objects.
5492 copy_non_heap_cl = ©_mark_non_heap_cl;
5493 }
5494
5495 // Keep alive closure.
5496 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, pss);
5497
5498 // Serial Complete GC closure
5499 G1STWDrainQueueClosure drain_queue(this, pss);
5500
5501 // Setup the soft refs policy...
5502 rp->setup_policy(false);
5503
5504 ReferenceProcessorStats stats;
5505 if (!rp->processing_is_mt()) {
5506 // Serial reference processing...
5507 stats = rp->process_discovered_references(&is_alive,
5508 &keep_alive,
5509 &drain_queue,
5510 NULL,
5511 _gc_timer_stw,
5512 _gc_tracer_stw->gc_id());
5513 } else {
5514 // Parallel reference processing
5515 assert(rp->num_q() == no_of_gc_workers, "sanity");
5516 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5517
5518 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5519 stats = rp->process_discovered_references(&is_alive,
5520 &keep_alive,
5521 &drain_queue,
5522 &par_task_executor,
5523 _gc_timer_stw,
5524 _gc_tracer_stw->gc_id());
5525 }
5526
5527 _gc_tracer_stw->report_gc_reference_stats(stats);
5528
5529 // We have completed copying any necessary live referent objects.
5530 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5531
5532 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5533 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5534 }
5535
5536 // Weak Reference processing during an evacuation pause (part 2).
5537 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5538 double ref_enq_start = os::elapsedTime();
5539
5540 ReferenceProcessor* rp = _ref_processor_stw;
5541 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5542
5543 // Now enqueue any remaining on the discovered lists on to
5544 // the pending list.
5545 if (!rp->processing_is_mt()) {
5546 // Serial reference processing...
5547 rp->enqueue_discovered_references();
5548 } else {
5549 // Parallel reference enqueueing
5550
5551 uint n_workers = workers()->active_workers();
5552
5553 assert(rp->num_q() == n_workers, "sanity");
5554 assert(n_workers <= rp->max_num_q(), "sanity");
5555
5556 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5557 rp->enqueue_discovered_references(&par_task_executor);
5558 }
5559
5560 rp->verify_no_references_recorded();
5561 assert(!rp->discovery_enabled(), "should have been disabled");
5562
5563 // FIXME
5564 // CM's reference processing also cleans up the string and symbol tables.
5565 // Should we do that here also? We could, but it is a serial operation
5566 // and could significantly increase the pause time.
5567
5568 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5569 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5570 }
5571
5572 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5573 _expand_heap_after_alloc_failure = true;
5574 _evacuation_failed = false;
5575
5576 // Should G1EvacuationFailureALot be in effect for this GC?
5577 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5578
5579 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5580
5581 // Disable the hot card cache.
5582 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5583 hot_card_cache->reset_hot_cache_claimed_index();
5584 hot_card_cache->set_use_cache(false);
5585
5586 const uint n_workers = workers()->active_workers();
5587
5588 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5589 double start_par_time_sec = os::elapsedTime();
5590 double end_par_time_sec;
5591
5592 {
5593 G1RootProcessor root_processor(this, n_workers);
5594 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5595 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5596 if (collector_state()->during_initial_mark_pause()) {
5597 ClassLoaderDataGraph::clear_claimed_marks();
5598 }
5599
5600 // The individual threads will set their evac-failure closures.
5601 if (PrintTerminationStats) {
5602 print_termination_stats_hdr(gclog_or_tty);
5603 }
5604
5605 workers()->run_task(&g1_par_task);
5606 end_par_time_sec = os::elapsedTime();
5607
5608 // Closing the inner scope will execute the destructor
5609 // for the G1RootProcessor object. We record the current
5610 // elapsed time before closing the scope so that time
5611 // taken for the destructor is NOT included in the
5612 // reported parallel time.
5613 }
5614
5615 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5616
5617 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5618 phase_times->record_par_time(par_time_ms);
5619
5620 double code_root_fixup_time_ms =
5621 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5622 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5623
5624 // Process any discovered reference objects - we have
5625 // to do this _before_ we retire the GC alloc regions
5626 // as we may have to copy some 'reachable' referent
5627 // objects (and their reachable sub-graphs) that were
5628 // not copied during the pause.
5629 process_discovered_references(per_thread_states);
5630
5631 if (G1StringDedup::is_enabled()) {
5632 double fixup_start = os::elapsedTime();
5633
5634 G1STWIsAliveClosure is_alive(this);
5635 G1KeepAliveClosure keep_alive(this);
5636 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5637
5638 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5639 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5640 }
5641
5642 _allocator->release_gc_alloc_regions(evacuation_info);
5643 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5644
5645 per_thread_states->flush();
5646
5647 record_obj_copy_mem_stats();
5648
5649 // Reset and re-enable the hot card cache.
5650 // Note the counts for the cards in the regions in the
5651 // collection set are reset when the collection set is freed.
5652 hot_card_cache->reset_hot_cache();
5653 hot_card_cache->set_use_cache(true);
5654
5655 purge_code_root_memory();
5656
5657 if (evacuation_failed()) {
5658 remove_self_forwarding_pointers();
5659
5660 // Reset the G1EvacuationFailureALot counters and flags
5661 // Note: the values are reset only when an actual
5662 // evacuation failure occurs.
5663 NOT_PRODUCT(reset_evacuation_should_fail();)
5664 }
5665
5666 // Enqueue any remaining references remaining on the STW
5667 // reference processor's discovered lists. We need to do
5668 // this after the card table is cleaned (and verified) as
5669 // the act of enqueueing entries on to the pending list
5670 // will log these updates (and dirty their associated
5671 // cards). We need these updates logged to update any
5672 // RSets.
5673 enqueue_discovered_references(per_thread_states);
5674
5675 redirty_logged_cards();
5676 #if defined(COMPILER2) || INCLUDE_JVMCI
5677 DerivedPointerTable::update_pointers();
5678 #endif
5679 }
5680
5681 void G1CollectedHeap::record_obj_copy_mem_stats() {
5682 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5683 create_g1_evac_summary(&_old_evac_stats));
5684 }
5685
5686 void G1CollectedHeap::free_region(HeapRegion* hr,
5687 FreeRegionList* free_list,
5688 bool par,
5689 bool locked) {
5690 assert(!hr->is_free(), "the region should not be free");
5691 assert(!hr->is_empty(), "the region should not be empty");
5692 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5693 assert(free_list != NULL, "pre-condition");
5694
5695 if (G1VerifyBitmaps) {
5696 MemRegion mr(hr->bottom(), hr->end());
5697 concurrent_mark()->clearRangePrevBitmap(mr);
5698 }
5699
5700 // Clear the card counts for this region.
5701 // Note: we only need to do this if the region is not young
5702 // (since we don't refine cards in young regions).
5703 if (!hr->is_young()) {
5704 _cg1r->hot_card_cache()->reset_card_counts(hr);
5705 }
5706 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5707 free_list->add_ordered(hr);
5708 }
5709
5710 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5711 FreeRegionList* free_list,
5712 bool par) {
5713 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5714 assert(free_list != NULL, "pre-condition");
5715
5716 size_t hr_capacity = hr->capacity();
5717 // We need to read this before we make the region non-humongous,
5718 // otherwise the information will be gone.
5719 uint last_index = hr->last_hc_index();
5720 hr->clear_humongous();
5721 free_region(hr, free_list, par);
5722
5723 uint i = hr->hrm_index() + 1;
5724 while (i < last_index) {
5725 HeapRegion* curr_hr = region_at(i);
5726 assert(curr_hr->is_continues_humongous(), "invariant");
5727 curr_hr->clear_humongous();
5728 free_region(curr_hr, free_list, par);
5729 i += 1;
5730 }
5731 }
5732
5733 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5734 const HeapRegionSetCount& humongous_regions_removed) {
5735 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5736 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5737 _old_set.bulk_remove(old_regions_removed);
5738 _humongous_set.bulk_remove(humongous_regions_removed);
5739 }
5740
5741 }
5742
5743 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5744 assert(list != NULL, "list can't be null");
5745 if (!list->is_empty()) {
5746 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5747 _hrm.insert_list_into_free_list(list);
5748 }
5749 }
5750
5751 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5752 decrease_used(bytes);
5753 }
5754
5755 class G1ParCleanupCTTask : public AbstractGangTask {
5756 G1SATBCardTableModRefBS* _ct_bs;
5757 G1CollectedHeap* _g1h;
5758 HeapRegion* volatile _su_head;
5759 public:
5760 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5761 G1CollectedHeap* g1h) :
5762 AbstractGangTask("G1 Par Cleanup CT Task"),
5763 _ct_bs(ct_bs), _g1h(g1h) { }
5764
5765 void work(uint worker_id) {
5766 HeapRegion* r;
5767 while (r = _g1h->pop_dirty_cards_region()) {
5768 clear_cards(r);
5769 }
5770 }
5771
5772 void clear_cards(HeapRegion* r) {
5773 // Cards of the survivors should have already been dirtied.
5774 if (!r->is_survivor()) {
5775 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5776 }
5777 }
5778 };
5779
5780 #ifndef PRODUCT
5781 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5782 G1CollectedHeap* _g1h;
5783 G1SATBCardTableModRefBS* _ct_bs;
5784 public:
5785 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5786 : _g1h(g1h), _ct_bs(ct_bs) { }
5787 virtual bool doHeapRegion(HeapRegion* r) {
5788 if (r->is_survivor()) {
5789 _g1h->verify_dirty_region(r);
5790 } else {
5791 _g1h->verify_not_dirty_region(r);
5792 }
5793 return false;
5794 }
5795 };
5796
5797 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5798 // All of the region should be clean.
5799 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5800 MemRegion mr(hr->bottom(), hr->end());
5801 ct_bs->verify_not_dirty_region(mr);
5802 }
5803
5804 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5805 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5806 // dirty allocated blocks as they allocate them. The thread that
5807 // retires each region and replaces it with a new one will do a
5808 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5809 // not dirty that area (one less thing to have to do while holding
5810 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5811 // is dirty.
5812 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5813 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5814 if (hr->is_young()) {
5815 ct_bs->verify_g1_young_region(mr);
5816 } else {
5817 ct_bs->verify_dirty_region(mr);
5818 }
5819 }
5820
5821 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5822 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5823 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5824 verify_dirty_region(hr);
5825 }
5826 }
5827
5828 void G1CollectedHeap::verify_dirty_young_regions() {
5829 verify_dirty_young_list(_young_list->first_region());
5830 }
5831
5832 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5833 HeapWord* tams, HeapWord* end) {
5834 guarantee(tams <= end,
5835 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5836 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5837 if (result < end) {
5838 gclog_or_tty->cr();
5839 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5840 bitmap_name, p2i(result));
5841 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5842 bitmap_name, p2i(tams), p2i(end));
5843 return false;
5844 }
5845 return true;
5846 }
5847
5848 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5849 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5850 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5851
5852 HeapWord* bottom = hr->bottom();
5853 HeapWord* ptams = hr->prev_top_at_mark_start();
5854 HeapWord* ntams = hr->next_top_at_mark_start();
5855 HeapWord* end = hr->end();
5856
5857 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5858
5859 bool res_n = true;
5860 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5861 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5862 // if we happen to be in that state.
5863 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5864 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5865 }
5866 if (!res_p || !res_n) {
5867 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5868 HR_FORMAT_PARAMS(hr));
5869 gclog_or_tty->print_cr("#### Caller: %s", caller);
5870 return false;
5871 }
5872 return true;
5873 }
5874
5875 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5876 if (!G1VerifyBitmaps) return;
5877
5878 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5879 }
5880
5881 class G1VerifyBitmapClosure : public HeapRegionClosure {
5882 private:
5883 const char* _caller;
5884 G1CollectedHeap* _g1h;
5885 bool _failures;
5886
5887 public:
5888 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5889 _caller(caller), _g1h(g1h), _failures(false) { }
5890
5891 bool failures() { return _failures; }
5892
5893 virtual bool doHeapRegion(HeapRegion* hr) {
5894 if (hr->is_continues_humongous()) return false;
5895
5896 bool result = _g1h->verify_bitmaps(_caller, hr);
5897 if (!result) {
5898 _failures = true;
5899 }
5900 return false;
5901 }
5902 };
5903
5904 void G1CollectedHeap::check_bitmaps(const char* caller) {
5905 if (!G1VerifyBitmaps) return;
5906
5907 G1VerifyBitmapClosure cl(caller, this);
5908 heap_region_iterate(&cl);
5909 guarantee(!cl.failures(), "bitmap verification");
5910 }
5911
5912 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5913 private:
5914 bool _failures;
5915 public:
5916 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5917
5918 virtual bool doHeapRegion(HeapRegion* hr) {
5919 uint i = hr->hrm_index();
5920 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5921 if (hr->is_humongous()) {
5922 if (hr->in_collection_set()) {
5923 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5924 _failures = true;
5925 return true;
5926 }
5927 if (cset_state.is_in_cset()) {
5928 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5929 _failures = true;
5930 return true;
5931 }
5932 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5933 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5934 _failures = true;
5935 return true;
5936 }
5937 } else {
5938 if (cset_state.is_humongous()) {
5939 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5940 _failures = true;
5941 return true;
5942 }
5943 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5944 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5945 hr->in_collection_set(), cset_state.value(), i);
5946 _failures = true;
5947 return true;
5948 }
5949 if (cset_state.is_in_cset()) {
5950 if (hr->is_young() != (cset_state.is_young())) {
5951 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5952 hr->is_young(), cset_state.value(), i);
5953 _failures = true;
5954 return true;
5955 }
5956 if (hr->is_old() != (cset_state.is_old())) {
5957 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5958 hr->is_old(), cset_state.value(), i);
5959 _failures = true;
5960 return true;
5961 }
5962 }
5963 }
5964 return false;
5965 }
5966
5967 bool failures() const { return _failures; }
5968 };
5969
5970 bool G1CollectedHeap::check_cset_fast_test() {
5971 G1CheckCSetFastTableClosure cl;
5972 _hrm.iterate(&cl);
5973 return !cl.failures();
5974 }
5975 #endif // PRODUCT
5976
5977 void G1CollectedHeap::cleanUpCardTable() {
5978 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5979 double start = os::elapsedTime();
5980
5981 {
5982 // Iterate over the dirty cards region list.
5983 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5984
5985 workers()->run_task(&cleanup_task);
5986 #ifndef PRODUCT
5987 if (G1VerifyCTCleanup || VerifyAfterGC) {
5988 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5989 heap_region_iterate(&cleanup_verifier);
5990 }
5991 #endif
5992 }
5993
5994 double elapsed = os::elapsedTime() - start;
5995 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5996 }
5997
5998 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5999 size_t pre_used = 0;
6000 FreeRegionList local_free_list("Local List for CSet Freeing");
6001
6002 double young_time_ms = 0.0;
6003 double non_young_time_ms = 0.0;
6004
6005 // Since the collection set is a superset of the the young list,
6006 // all we need to do to clear the young list is clear its
6007 // head and length, and unlink any young regions in the code below
6008 _young_list->clear();
6009
6010 G1CollectorPolicy* policy = g1_policy();
6011
6012 double start_sec = os::elapsedTime();
6013 bool non_young = true;
6014
6015 HeapRegion* cur = cs_head;
6016 int age_bound = -1;
6017 size_t rs_lengths = 0;
6018
6019 while (cur != NULL) {
6020 assert(!is_on_master_free_list(cur), "sanity");
6021 if (non_young) {
6022 if (cur->is_young()) {
6023 double end_sec = os::elapsedTime();
6024 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6025 non_young_time_ms += elapsed_ms;
6026
6027 start_sec = os::elapsedTime();
6028 non_young = false;
6029 }
6030 } else {
6031 if (!cur->is_young()) {
6032 double end_sec = os::elapsedTime();
6033 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6034 young_time_ms += elapsed_ms;
6035
6036 start_sec = os::elapsedTime();
6037 non_young = true;
6038 }
6039 }
6040
6041 rs_lengths += cur->rem_set()->occupied_locked();
6042
6043 HeapRegion* next = cur->next_in_collection_set();
6044 assert(cur->in_collection_set(), "bad CS");
6045 cur->set_next_in_collection_set(NULL);
6046 clear_in_cset(cur);
6047
6048 if (cur->is_young()) {
6049 int index = cur->young_index_in_cset();
6050 assert(index != -1, "invariant");
6051 assert((uint) index < policy->young_cset_region_length(), "invariant");
6052 size_t words_survived = surviving_young_words[index];
6053 cur->record_surv_words_in_group(words_survived);
6054
6055 // At this point the we have 'popped' cur from the collection set
6056 // (linked via next_in_collection_set()) but it is still in the
6057 // young list (linked via next_young_region()). Clear the
6058 // _next_young_region field.
6059 cur->set_next_young_region(NULL);
6060 } else {
6061 int index = cur->young_index_in_cset();
6062 assert(index == -1, "invariant");
6063 }
6064
6065 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6066 (!cur->is_young() && cur->young_index_in_cset() == -1),
6067 "invariant" );
6068
6069 if (!cur->evacuation_failed()) {
6070 MemRegion used_mr = cur->used_region();
6071
6072 // And the region is empty.
6073 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6074 pre_used += cur->used();
6075 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6076 } else {
6077 cur->uninstall_surv_rate_group();
6078 if (cur->is_young()) {
6079 cur->set_young_index_in_cset(-1);
6080 }
6081 cur->set_evacuation_failed(false);
6082 // The region is now considered to be old.
6083 cur->set_old();
6084 // Do some allocation statistics accounting. Regions that failed evacuation
6085 // are always made old, so there is no need to update anything in the young
6086 // gen statistics, but we need to update old gen statistics.
6087 size_t used_words = cur->marked_bytes() / HeapWordSize;
6088 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
6089 _old_set.add(cur);
6090 evacuation_info.increment_collectionset_used_after(cur->used());
6091 }
6092 cur = next;
6093 }
6094
6095 evacuation_info.set_regions_freed(local_free_list.length());
6096 policy->record_max_rs_lengths(rs_lengths);
6097 policy->cset_regions_freed();
6098
6099 double end_sec = os::elapsedTime();
6100 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6101
6102 if (non_young) {
6103 non_young_time_ms += elapsed_ms;
6104 } else {
6105 young_time_ms += elapsed_ms;
6106 }
6107
6108 prepend_to_freelist(&local_free_list);
6109 decrement_summary_bytes(pre_used);
6110 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6111 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6112 }
6113
6114 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6115 private:
6116 FreeRegionList* _free_region_list;
6117 HeapRegionSet* _proxy_set;
6118 HeapRegionSetCount _humongous_regions_removed;
6119 size_t _freed_bytes;
6120 public:
6121
6122 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6123 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6124 }
6125
6126 virtual bool doHeapRegion(HeapRegion* r) {
6127 if (!r->is_starts_humongous()) {
6128 return false;
6129 }
6130
6131 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6132
6133 oop obj = (oop)r->bottom();
6134 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6135
6136 // The following checks whether the humongous object is live are sufficient.
6137 // The main additional check (in addition to having a reference from the roots
6138 // or the young gen) is whether the humongous object has a remembered set entry.
6139 //
6140 // A humongous object cannot be live if there is no remembered set for it
6141 // because:
6142 // - there can be no references from within humongous starts regions referencing
6143 // the object because we never allocate other objects into them.
6144 // (I.e. there are no intra-region references that may be missed by the
6145 // remembered set)
6146 // - as soon there is a remembered set entry to the humongous starts region
6147 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6148 // until the end of a concurrent mark.
6149 //
6150 // It is not required to check whether the object has been found dead by marking
6151 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6152 // all objects allocated during that time are considered live.
6153 // SATB marking is even more conservative than the remembered set.
6154 // So if at this point in the collection there is no remembered set entry,
6155 // nobody has a reference to it.
6156 // At the start of collection we flush all refinement logs, and remembered sets
6157 // are completely up-to-date wrt to references to the humongous object.
6158 //
6159 // Other implementation considerations:
6160 // - never consider object arrays at this time because they would pose
6161 // considerable effort for cleaning up the the remembered sets. This is
6162 // required because stale remembered sets might reference locations that
6163 // are currently allocated into.
6164 uint region_idx = r->hrm_index();
6165 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6166 !r->rem_set()->is_empty()) {
6167
6168 if (G1TraceEagerReclaimHumongousObjects) {
6169 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",
6170 region_idx,
6171 (size_t)obj->size() * HeapWordSize,
6172 p2i(r->bottom()),
6173 r->region_num(),
6174 r->rem_set()->occupied(),
6175 r->rem_set()->strong_code_roots_list_length(),
6176 next_bitmap->isMarked(r->bottom()),
6177 g1h->is_humongous_reclaim_candidate(region_idx),
6178 obj->is_typeArray()
6179 );
6180 }
6181
6182 return false;
6183 }
6184
6185 guarantee(obj->is_typeArray(),
6186 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6187 PTR_FORMAT " is not.",
6188 p2i(r->bottom())));
6189
6190 if (G1TraceEagerReclaimHumongousObjects) {
6191 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",
6192 region_idx,
6193 (size_t)obj->size() * HeapWordSize,
6194 p2i(r->bottom()),
6195 r->region_num(),
6196 r->rem_set()->occupied(),
6197 r->rem_set()->strong_code_roots_list_length(),
6198 next_bitmap->isMarked(r->bottom()),
6199 g1h->is_humongous_reclaim_candidate(region_idx),
6200 obj->is_typeArray()
6201 );
6202 }
6203 // Need to clear mark bit of the humongous object if already set.
6204 if (next_bitmap->isMarked(r->bottom())) {
6205 next_bitmap->clear(r->bottom());
6206 }
6207 _freed_bytes += r->used();
6208 r->set_containing_set(NULL);
6209 _humongous_regions_removed.increment(1u, r->capacity());
6210 g1h->free_humongous_region(r, _free_region_list, false);
6211
6212 return false;
6213 }
6214
6215 HeapRegionSetCount& humongous_free_count() {
6216 return _humongous_regions_removed;
6217 }
6218
6219 size_t bytes_freed() const {
6220 return _freed_bytes;
6221 }
6222
6223 size_t humongous_reclaimed() const {
6224 return _humongous_regions_removed.length();
6225 }
6226 };
6227
6228 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6229 assert_at_safepoint(true);
6230
6231 if (!G1EagerReclaimHumongousObjects ||
6232 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6233 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6234 return;
6235 }
6236
6237 double start_time = os::elapsedTime();
6238
6239 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6240
6241 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6242 heap_region_iterate(&cl);
6243
6244 HeapRegionSetCount empty_set;
6245 remove_from_old_sets(empty_set, cl.humongous_free_count());
6246
6247 G1HRPrinter* hrp = hr_printer();
6248 if (hrp->is_active()) {
6249 FreeRegionListIterator iter(&local_cleanup_list);
6250 while (iter.more_available()) {
6251 HeapRegion* hr = iter.get_next();
6252 hrp->cleanup(hr);
6253 }
6254 }
6255
6256 prepend_to_freelist(&local_cleanup_list);
6257 decrement_summary_bytes(cl.bytes_freed());
6258
6259 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6260 cl.humongous_reclaimed());
6261 }
6262
6263 // This routine is similar to the above but does not record
6264 // any policy statistics or update free lists; we are abandoning
6265 // the current incremental collection set in preparation of a
6266 // full collection. After the full GC we will start to build up
6267 // the incremental collection set again.
6268 // This is only called when we're doing a full collection
6269 // and is immediately followed by the tearing down of the young list.
6270
6271 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6272 HeapRegion* cur = cs_head;
6273
6274 while (cur != NULL) {
6275 HeapRegion* next = cur->next_in_collection_set();
6276 assert(cur->in_collection_set(), "bad CS");
6277 cur->set_next_in_collection_set(NULL);
6278 clear_in_cset(cur);
6279 cur->set_young_index_in_cset(-1);
6280 cur = next;
6281 }
6282 }
6283
6284 void G1CollectedHeap::set_free_regions_coming() {
6285 if (G1ConcRegionFreeingVerbose) {
6286 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6287 "setting free regions coming");
6288 }
6289
6290 assert(!free_regions_coming(), "pre-condition");
6291 _free_regions_coming = true;
6292 }
6293
6294 void G1CollectedHeap::reset_free_regions_coming() {
6295 assert(free_regions_coming(), "pre-condition");
6296
6297 {
6298 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6299 _free_regions_coming = false;
6300 SecondaryFreeList_lock->notify_all();
6301 }
6302
6303 if (G1ConcRegionFreeingVerbose) {
6304 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6305 "reset free regions coming");
6306 }
6307 }
6308
6309 void G1CollectedHeap::wait_while_free_regions_coming() {
6310 // Most of the time we won't have to wait, so let's do a quick test
6311 // first before we take the lock.
6312 if (!free_regions_coming()) {
6313 return;
6314 }
6315
6316 if (G1ConcRegionFreeingVerbose) {
6317 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6318 "waiting for free regions");
6319 }
6320
6321 {
6322 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6323 while (free_regions_coming()) {
6324 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6325 }
6326 }
6327
6328 if (G1ConcRegionFreeingVerbose) {
6329 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6330 "done waiting for free regions");
6331 }
6332 }
6333
6334 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
6335 return _allocator->is_retained_old_region(hr);
6336 }
6337
6338 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6339 _young_list->push_region(hr);
6340 }
6341
6342 class NoYoungRegionsClosure: public HeapRegionClosure {
6343 private:
6344 bool _success;
6345 public:
6346 NoYoungRegionsClosure() : _success(true) { }
6347 bool doHeapRegion(HeapRegion* r) {
6348 if (r->is_young()) {
6349 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6350 p2i(r->bottom()), p2i(r->end()));
6351 _success = false;
6352 }
6353 return false;
6354 }
6355 bool success() { return _success; }
6356 };
6357
6358 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6359 bool ret = _young_list->check_list_empty(check_sample);
6360
6361 if (check_heap) {
6362 NoYoungRegionsClosure closure;
6363 heap_region_iterate(&closure);
6364 ret = ret && closure.success();
6365 }
6366
6367 return ret;
6368 }
6369
6370 class TearDownRegionSetsClosure : public HeapRegionClosure {
6371 private:
6372 HeapRegionSet *_old_set;
6373
6374 public:
6375 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6376
6377 bool doHeapRegion(HeapRegion* r) {
6378 if (r->is_old()) {
6379 _old_set->remove(r);
6380 } else {
6381 // We ignore free regions, we'll empty the free list afterwards.
6382 // We ignore young regions, we'll empty the young list afterwards.
6383 // We ignore humongous regions, we're not tearing down the
6384 // humongous regions set.
6385 assert(r->is_free() || r->is_young() || r->is_humongous(),
6386 "it cannot be another type");
6387 }
6388 return false;
6389 }
6390
6391 ~TearDownRegionSetsClosure() {
6392 assert(_old_set->is_empty(), "post-condition");
6393 }
6394 };
6395
6396 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6397 assert_at_safepoint(true /* should_be_vm_thread */);
6398
6399 if (!free_list_only) {
6400 TearDownRegionSetsClosure cl(&_old_set);
6401 heap_region_iterate(&cl);
6402
6403 // Note that emptying the _young_list is postponed and instead done as
6404 // the first step when rebuilding the regions sets again. The reason for
6405 // this is that during a full GC string deduplication needs to know if
6406 // a collected region was young or old when the full GC was initiated.
6407 }
6408 _hrm.remove_all_free_regions();
6409 }
6410
6411 void G1CollectedHeap::increase_used(size_t bytes) {
6412 _summary_bytes_used += bytes;
6413 }
6414
6415 void G1CollectedHeap::decrease_used(size_t bytes) {
6416 assert(_summary_bytes_used >= bytes,
6417 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6418 _summary_bytes_used, bytes));
6419 _summary_bytes_used -= bytes;
6420 }
6421
6422 void G1CollectedHeap::set_used(size_t bytes) {
6423 _summary_bytes_used = bytes;
6424 }
6425
6426 class RebuildRegionSetsClosure : public HeapRegionClosure {
6427 private:
6428 bool _free_list_only;
6429 HeapRegionSet* _old_set;
6430 HeapRegionManager* _hrm;
6431 size_t _total_used;
6432
6433 public:
6434 RebuildRegionSetsClosure(bool free_list_only,
6435 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6436 _free_list_only(free_list_only),
6437 _old_set(old_set), _hrm(hrm), _total_used(0) {
6438 assert(_hrm->num_free_regions() == 0, "pre-condition");
6439 if (!free_list_only) {
6440 assert(_old_set->is_empty(), "pre-condition");
6441 }
6442 }
6443
6444 bool doHeapRegion(HeapRegion* r) {
6445 if (r->is_continues_humongous()) {
6446 return false;
6447 }
6448
6449 if (r->is_empty()) {
6450 // Add free regions to the free list
6451 r->set_free();
6452 r->set_allocation_context(AllocationContext::system());
6453 _hrm->insert_into_free_list(r);
6454 } else if (!_free_list_only) {
6455 assert(!r->is_young(), "we should not come across young regions");
6456
6457 if (r->is_humongous()) {
6458 // We ignore humongous regions. We left the humongous set unchanged.
6459 } else {
6460 // Objects that were compacted would have ended up on regions
6461 // that were previously old or free. Archive regions (which are
6462 // old) will not have been touched.
6463 assert(r->is_free() || r->is_old(), "invariant");
6464 // We now consider them old, so register as such. Leave
6465 // archive regions set that way, however, while still adding
6466 // them to the old set.
6467 if (!r->is_archive()) {
6468 r->set_old();
6469 }
6470 _old_set->add(r);
6471 }
6472 _total_used += r->used();
6473 }
6474
6475 return false;
6476 }
6477
6478 size_t total_used() {
6479 return _total_used;
6480 }
6481 };
6482
6483 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6484 assert_at_safepoint(true /* should_be_vm_thread */);
6485
6486 if (!free_list_only) {
6487 _young_list->empty_list();
6488 }
6489
6490 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6491 heap_region_iterate(&cl);
6492
6493 if (!free_list_only) {
6494 set_used(cl.total_used());
6495 if (_archive_allocator != NULL) {
6496 _archive_allocator->clear_used();
6497 }
6498 }
6499 assert(used_unlocked() == recalculate_used(),
6500 err_msg("inconsistent used_unlocked(), "
6501 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6502 used_unlocked(), recalculate_used()));
6503 }
6504
6505 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6506 _refine_cte_cl->set_concurrent(concurrent);
6507 }
6508
6509 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6510 HeapRegion* hr = heap_region_containing(p);
6511 return hr->is_in(p);
6512 }
6513
6514 // Methods for the mutator alloc region
6515
6516 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6517 bool force) {
6518 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6519 assert(!force || g1_policy()->can_expand_young_list(),
6520 "if force is true we should be able to expand the young list");
6521 bool young_list_full = g1_policy()->is_young_list_full();
6522 if (force || !young_list_full) {
6523 HeapRegion* new_alloc_region = new_region(word_size,
6524 false /* is_old */,
6525 false /* do_expand */);
6526 if (new_alloc_region != NULL) {
6527 set_region_short_lived_locked(new_alloc_region);
6528 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6529 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6530 return new_alloc_region;
6531 }
6532 }
6533 return NULL;
6534 }
6535
6536 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6537 size_t allocated_bytes) {
6538 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6539 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6540
6541 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6542 increase_used(allocated_bytes);
6543 _hr_printer.retire(alloc_region);
6544 // We update the eden sizes here, when the region is retired,
6545 // instead of when it's allocated, since this is the point that its
6546 // used space has been recored in _summary_bytes_used.
6547 g1mm()->update_eden_size();
6548 }
6549
6550 // Methods for the GC alloc regions
6551
6552 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6553 uint count,
6554 InCSetState dest) {
6555 assert(FreeList_lock->owned_by_self(), "pre-condition");
6556
6557 if (count < g1_policy()->max_regions(dest)) {
6558 const bool is_survivor = (dest.is_young());
6559 HeapRegion* new_alloc_region = new_region(word_size,
6560 !is_survivor,
6561 true /* do_expand */);
6562 if (new_alloc_region != NULL) {
6563 // We really only need to do this for old regions given that we
6564 // should never scan survivors. But it doesn't hurt to do it
6565 // for survivors too.
6566 new_alloc_region->record_timestamp();
6567 if (is_survivor) {
6568 new_alloc_region->set_survivor();
6569 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6570 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6571 } else {
6572 new_alloc_region->set_old();
6573 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6574 check_bitmaps("Old Region Allocation", new_alloc_region);
6575 }
6576 bool during_im = collector_state()->during_initial_mark_pause();
6577 new_alloc_region->note_start_of_copying(during_im);
6578 return new_alloc_region;
6579 }
6580 }
6581 return NULL;
6582 }
6583
6584 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6585 size_t allocated_bytes,
6586 InCSetState dest) {
6587 bool during_im = collector_state()->during_initial_mark_pause();
6588 alloc_region->note_end_of_copying(during_im);
6589 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6590 if (dest.is_young()) {
6591 young_list()->add_survivor_region(alloc_region);
6592 } else {
6593 _old_set.add(alloc_region);
6594 }
6595 _hr_printer.retire(alloc_region);
6596 }
6597
6598 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6599 bool expanded = false;
6600 uint index = _hrm.find_highest_free(&expanded);
6601
6602 if (index != G1_NO_HRM_INDEX) {
6603 if (expanded) {
6604 ergo_verbose1(ErgoHeapSizing,
6605 "attempt heap expansion",
6606 ergo_format_reason("requested address range outside heap bounds")
6607 ergo_format_byte("region size"),
6608 HeapRegion::GrainWords * HeapWordSize);
6609 }
6610 _hrm.allocate_free_regions_starting_at(index, 1);
6611 return region_at(index);
6612 }
6613 return NULL;
6614 }
6615
6616 // Heap region set verification
6617
6618 class VerifyRegionListsClosure : public HeapRegionClosure {
6619 private:
6620 HeapRegionSet* _old_set;
6621 HeapRegionSet* _humongous_set;
6622 HeapRegionManager* _hrm;
6623
6624 public:
6625 HeapRegionSetCount _old_count;
6626 HeapRegionSetCount _humongous_count;
6627 HeapRegionSetCount _free_count;
6628
6629 VerifyRegionListsClosure(HeapRegionSet* old_set,
6630 HeapRegionSet* humongous_set,
6631 HeapRegionManager* hrm) :
6632 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6633 _old_count(), _humongous_count(), _free_count(){ }
6634
6635 bool doHeapRegion(HeapRegion* hr) {
6636 if (hr->is_continues_humongous()) {
6637 return false;
6638 }
6639
6640 if (hr->is_young()) {
6641 // TODO
6642 } else if (hr->is_starts_humongous()) {
6643 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6644 _humongous_count.increment(1u, hr->capacity());
6645 } else if (hr->is_empty()) {
6646 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6647 _free_count.increment(1u, hr->capacity());
6648 } else if (hr->is_old()) {
6649 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6650 _old_count.increment(1u, hr->capacity());
6651 } else {
6652 // There are no other valid region types. Check for one invalid
6653 // one we can identify: pinned without old or humongous set.
6654 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6655 ShouldNotReachHere();
6656 }
6657 return false;
6658 }
6659
6660 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6661 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6662 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6663 old_set->total_capacity_bytes(), _old_count.capacity()));
6664
6665 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6666 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6667 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6668
6669 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()));
6670 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6671 free_list->total_capacity_bytes(), _free_count.capacity()));
6672 }
6673 };
6674
6675 void G1CollectedHeap::verify_region_sets() {
6676 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6677
6678 // First, check the explicit lists.
6679 _hrm.verify();
6680 {
6681 // Given that a concurrent operation might be adding regions to
6682 // the secondary free list we have to take the lock before
6683 // verifying it.
6684 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6685 _secondary_free_list.verify_list();
6686 }
6687
6688 // If a concurrent region freeing operation is in progress it will
6689 // be difficult to correctly attributed any free regions we come
6690 // across to the correct free list given that they might belong to
6691 // one of several (free_list, secondary_free_list, any local lists,
6692 // etc.). So, if that's the case we will skip the rest of the
6693 // verification operation. Alternatively, waiting for the concurrent
6694 // operation to complete will have a non-trivial effect on the GC's
6695 // operation (no concurrent operation will last longer than the
6696 // interval between two calls to verification) and it might hide
6697 // any issues that we would like to catch during testing.
6698 if (free_regions_coming()) {
6699 return;
6700 }
6701
6702 // Make sure we append the secondary_free_list on the free_list so
6703 // that all free regions we will come across can be safely
6704 // attributed to the free_list.
6705 append_secondary_free_list_if_not_empty_with_lock();
6706
6707 // Finally, make sure that the region accounting in the lists is
6708 // consistent with what we see in the heap.
6709
6710 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6711 heap_region_iterate(&cl);
6712 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6713 }
6714
6715 // Optimized nmethod scanning
6716
6717 class RegisterNMethodOopClosure: public OopClosure {
6718 G1CollectedHeap* _g1h;
6719 nmethod* _nm;
6720
6721 template <class T> void do_oop_work(T* p) {
6722 T heap_oop = oopDesc::load_heap_oop(p);
6723 if (!oopDesc::is_null(heap_oop)) {
6724 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6725 HeapRegion* hr = _g1h->heap_region_containing(obj);
6726 assert(!hr->is_continues_humongous(),
6727 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6728 " starting at " HR_FORMAT,
6729 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6730
6731 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6732 hr->add_strong_code_root_locked(_nm);
6733 }
6734 }
6735
6736 public:
6737 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6738 _g1h(g1h), _nm(nm) {}
6739
6740 void do_oop(oop* p) { do_oop_work(p); }
6741 void do_oop(narrowOop* p) { do_oop_work(p); }
6742 };
6743
6744 class UnregisterNMethodOopClosure: public OopClosure {
6745 G1CollectedHeap* _g1h;
6746 nmethod* _nm;
6747
6748 template <class T> void do_oop_work(T* p) {
6749 T heap_oop = oopDesc::load_heap_oop(p);
6750 if (!oopDesc::is_null(heap_oop)) {
6751 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6752 HeapRegion* hr = _g1h->heap_region_containing(obj);
6753 assert(!hr->is_continues_humongous(),
6754 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6755 " starting at " HR_FORMAT,
6756 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6757
6758 hr->remove_strong_code_root(_nm);
6759 }
6760 }
6761
6762 public:
6763 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6764 _g1h(g1h), _nm(nm) {}
6765
6766 void do_oop(oop* p) { do_oop_work(p); }
6767 void do_oop(narrowOop* p) { do_oop_work(p); }
6768 };
6769
6770 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6771 CollectedHeap::register_nmethod(nm);
6772
6773 guarantee(nm != NULL, "sanity");
6774 RegisterNMethodOopClosure reg_cl(this, nm);
6775 nm->oops_do(®_cl);
6776 }
6777
6778 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6779 CollectedHeap::unregister_nmethod(nm);
6780
6781 guarantee(nm != NULL, "sanity");
6782 UnregisterNMethodOopClosure reg_cl(this, nm);
6783 nm->oops_do(®_cl, true);
6784 }
6785
6786 void G1CollectedHeap::purge_code_root_memory() {
6787 double purge_start = os::elapsedTime();
6788 G1CodeRootSet::purge();
6789 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6790 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6791 }
6792
6793 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6794 G1CollectedHeap* _g1h;
6795
6796 public:
6797 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6798 _g1h(g1h) {}
6799
6800 void do_code_blob(CodeBlob* cb) {
6801 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6802 if (nm == NULL) {
6803 return;
6804 }
6805
6806 if (ScavengeRootsInCode) {
6807 _g1h->register_nmethod(nm);
6808 }
6809 }
6810 };
6811
6812 void G1CollectedHeap::rebuild_strong_code_roots() {
6813 RebuildStrongCodeRootClosure blob_cl(this);
6814 CodeCache::blobs_do(&blob_cl);
6815 }