1 /*
2 * Copyright (c) 2001, 2010, 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 "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/concurrentZFThread.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1MarkSweep.hpp"
35 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
36 #include "gc_implementation/g1/g1RemSet.inline.hpp"
37 #include "gc_implementation/g1/heapRegionRemSet.hpp"
38 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
39 #include "gc_implementation/g1/vm_operations_g1.hpp"
40 #include "gc_implementation/shared/isGCActiveMark.hpp"
41 #include "memory/gcLocker.inline.hpp"
42 #include "memory/genOopClosures.inline.hpp"
43 #include "memory/generationSpec.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.pcgc.inline.hpp"
46 #include "runtime/aprofiler.hpp"
47 #include "runtime/vmThread.hpp"
48
49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
50
51 // turn it on so that the contents of the young list (scan-only /
52 // to-be-collected) are printed at "strategic" points before / during
53 // / after the collection --- this is useful for debugging
54 #define YOUNG_LIST_VERBOSE 0
55 // CURRENT STATUS
56 // This file is under construction. Search for "FIXME".
57
58 // INVARIANTS/NOTES
59 //
60 // All allocation activity covered by the G1CollectedHeap interface is
61 // serialized by acquiring the HeapLock. This happens in
62 // mem_allocate_work, which all such allocation functions call.
63 // (Note that this does not apply to TLAB allocation, which is not part
64 // of this interface: it is done by clients of this interface.)
65
66 // Local to this file.
67
68 class RefineCardTableEntryClosure: public CardTableEntryClosure {
69 SuspendibleThreadSet* _sts;
70 G1RemSet* _g1rs;
71 ConcurrentG1Refine* _cg1r;
72 bool _concurrent;
73 public:
74 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
75 G1RemSet* g1rs,
76 ConcurrentG1Refine* cg1r) :
77 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
78 {}
79 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
80 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
81 // This path is executed by the concurrent refine or mutator threads,
82 // concurrently, and so we do not care if card_ptr contains references
83 // that point into the collection set.
84 assert(!oops_into_cset, "should be");
85
86 if (_concurrent && _sts->should_yield()) {
87 // Caller will actually yield.
88 return false;
89 }
90 // Otherwise, we finished successfully; return true.
91 return true;
92 }
93 void set_concurrent(bool b) { _concurrent = b; }
94 };
95
96
97 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
98 int _calls;
99 G1CollectedHeap* _g1h;
100 CardTableModRefBS* _ctbs;
101 int _histo[256];
102 public:
103 ClearLoggedCardTableEntryClosure() :
104 _calls(0)
105 {
106 _g1h = G1CollectedHeap::heap();
107 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
108 for (int i = 0; i < 256; i++) _histo[i] = 0;
109 }
110 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
111 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
112 _calls++;
113 unsigned char* ujb = (unsigned char*)card_ptr;
114 int ind = (int)(*ujb);
115 _histo[ind]++;
116 *card_ptr = -1;
117 }
118 return true;
119 }
120 int calls() { return _calls; }
121 void print_histo() {
122 gclog_or_tty->print_cr("Card table value histogram:");
123 for (int i = 0; i < 256; i++) {
124 if (_histo[i] != 0) {
125 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
126 }
127 }
128 }
129 };
130
131 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
132 int _calls;
133 G1CollectedHeap* _g1h;
134 CardTableModRefBS* _ctbs;
135 public:
136 RedirtyLoggedCardTableEntryClosure() :
137 _calls(0)
138 {
139 _g1h = G1CollectedHeap::heap();
140 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
141 }
142 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
143 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
144 _calls++;
145 *card_ptr = 0;
146 }
147 return true;
148 }
149 int calls() { return _calls; }
150 };
151
152 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
153 public:
154 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
155 *card_ptr = CardTableModRefBS::dirty_card_val();
156 return true;
157 }
158 };
159
160 YoungList::YoungList(G1CollectedHeap* g1h)
161 : _g1h(g1h), _head(NULL),
162 _length(0),
163 _last_sampled_rs_lengths(0),
164 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
165 {
166 guarantee( check_list_empty(false), "just making sure..." );
167 }
168
169 void YoungList::push_region(HeapRegion *hr) {
170 assert(!hr->is_young(), "should not already be young");
171 assert(hr->get_next_young_region() == NULL, "cause it should!");
172
173 hr->set_next_young_region(_head);
174 _head = hr;
175
176 hr->set_young();
177 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
178 ++_length;
179 }
180
181 void YoungList::add_survivor_region(HeapRegion* hr) {
182 assert(hr->is_survivor(), "should be flagged as survivor region");
183 assert(hr->get_next_young_region() == NULL, "cause it should!");
184
185 hr->set_next_young_region(_survivor_head);
186 if (_survivor_head == NULL) {
187 _survivor_tail = hr;
188 }
189 _survivor_head = hr;
190
191 ++_survivor_length;
192 }
193
194 void YoungList::empty_list(HeapRegion* list) {
195 while (list != NULL) {
196 HeapRegion* next = list->get_next_young_region();
197 list->set_next_young_region(NULL);
198 list->uninstall_surv_rate_group();
199 list->set_not_young();
200 list = next;
201 }
202 }
203
204 void YoungList::empty_list() {
205 assert(check_list_well_formed(), "young list should be well formed");
206
207 empty_list(_head);
208 _head = NULL;
209 _length = 0;
210
211 empty_list(_survivor_head);
212 _survivor_head = NULL;
213 _survivor_tail = NULL;
214 _survivor_length = 0;
215
216 _last_sampled_rs_lengths = 0;
217
218 assert(check_list_empty(false), "just making sure...");
219 }
220
221 bool YoungList::check_list_well_formed() {
222 bool ret = true;
223
224 size_t length = 0;
225 HeapRegion* curr = _head;
226 HeapRegion* last = NULL;
227 while (curr != NULL) {
228 if (!curr->is_young()) {
229 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
230 "incorrectly tagged (y: %d, surv: %d)",
231 curr->bottom(), curr->end(),
232 curr->is_young(), curr->is_survivor());
233 ret = false;
234 }
235 ++length;
236 last = curr;
237 curr = curr->get_next_young_region();
238 }
239 ret = ret && (length == _length);
240
241 if (!ret) {
242 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
243 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
244 length, _length);
245 }
246
247 return ret;
248 }
249
250 bool YoungList::check_list_empty(bool check_sample) {
251 bool ret = true;
252
253 if (_length != 0) {
254 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
255 _length);
256 ret = false;
257 }
258 if (check_sample && _last_sampled_rs_lengths != 0) {
259 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
260 ret = false;
261 }
262 if (_head != NULL) {
263 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
264 ret = false;
265 }
266 if (!ret) {
267 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
268 }
269
270 return ret;
271 }
272
273 void
274 YoungList::rs_length_sampling_init() {
275 _sampled_rs_lengths = 0;
276 _curr = _head;
277 }
278
279 bool
280 YoungList::rs_length_sampling_more() {
281 return _curr != NULL;
282 }
283
284 void
285 YoungList::rs_length_sampling_next() {
286 assert( _curr != NULL, "invariant" );
287 size_t rs_length = _curr->rem_set()->occupied();
288
289 _sampled_rs_lengths += rs_length;
290
291 // The current region may not yet have been added to the
292 // incremental collection set (it gets added when it is
293 // retired as the current allocation region).
294 if (_curr->in_collection_set()) {
295 // Update the collection set policy information for this region
296 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
297 }
298
299 _curr = _curr->get_next_young_region();
300 if (_curr == NULL) {
301 _last_sampled_rs_lengths = _sampled_rs_lengths;
302 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
303 }
304 }
305
306 void
307 YoungList::reset_auxilary_lists() {
308 guarantee( is_empty(), "young list should be empty" );
309 assert(check_list_well_formed(), "young list should be well formed");
310
311 // Add survivor regions to SurvRateGroup.
312 _g1h->g1_policy()->note_start_adding_survivor_regions();
313 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
314
315 for (HeapRegion* curr = _survivor_head;
316 curr != NULL;
317 curr = curr->get_next_young_region()) {
318 _g1h->g1_policy()->set_region_survivors(curr);
319
320 // The region is a non-empty survivor so let's add it to
321 // the incremental collection set for the next evacuation
322 // pause.
323 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
324 }
325 _g1h->g1_policy()->note_stop_adding_survivor_regions();
326
327 _head = _survivor_head;
328 _length = _survivor_length;
329 if (_survivor_head != NULL) {
330 assert(_survivor_tail != NULL, "cause it shouldn't be");
331 assert(_survivor_length > 0, "invariant");
332 _survivor_tail->set_next_young_region(NULL);
333 }
334
335 // Don't clear the survivor list handles until the start of
336 // the next evacuation pause - we need it in order to re-tag
337 // the survivor regions from this evacuation pause as 'young'
338 // at the start of the next.
339
340 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
341
342 assert(check_list_well_formed(), "young list should be well formed");
343 }
344
345 void YoungList::print() {
346 HeapRegion* lists[] = {_head, _survivor_head};
347 const char* names[] = {"YOUNG", "SURVIVOR"};
348
349 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
350 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
351 HeapRegion *curr = lists[list];
352 if (curr == NULL)
353 gclog_or_tty->print_cr(" empty");
354 while (curr != NULL) {
355 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
356 "age: %4d, y: %d, surv: %d",
357 curr->bottom(), curr->end(),
358 curr->top(),
359 curr->prev_top_at_mark_start(),
360 curr->next_top_at_mark_start(),
361 curr->top_at_conc_mark_count(),
362 curr->age_in_surv_rate_group_cond(),
363 curr->is_young(),
364 curr->is_survivor());
365 curr = curr->get_next_young_region();
366 }
367 }
368
369 gclog_or_tty->print_cr("");
370 }
371
372 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
373 {
374 // Claim the right to put the region on the dirty cards region list
375 // by installing a self pointer.
376 HeapRegion* next = hr->get_next_dirty_cards_region();
377 if (next == NULL) {
378 HeapRegion* res = (HeapRegion*)
379 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
380 NULL);
381 if (res == NULL) {
382 HeapRegion* head;
383 do {
384 // Put the region to the dirty cards region list.
385 head = _dirty_cards_region_list;
386 next = (HeapRegion*)
387 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
388 if (next == head) {
389 assert(hr->get_next_dirty_cards_region() == hr,
390 "hr->get_next_dirty_cards_region() != hr");
391 if (next == NULL) {
392 // The last region in the list points to itself.
393 hr->set_next_dirty_cards_region(hr);
394 } else {
395 hr->set_next_dirty_cards_region(next);
396 }
397 }
398 } while (next != head);
399 }
400 }
401 }
402
403 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
404 {
405 HeapRegion* head;
406 HeapRegion* hr;
407 do {
408 head = _dirty_cards_region_list;
409 if (head == NULL) {
410 return NULL;
411 }
412 HeapRegion* new_head = head->get_next_dirty_cards_region();
413 if (head == new_head) {
414 // The last region.
415 new_head = NULL;
416 }
417 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
418 head);
419 } while (hr != head);
420 assert(hr != NULL, "invariant");
421 hr->set_next_dirty_cards_region(NULL);
422 return hr;
423 }
424
425 void G1CollectedHeap::stop_conc_gc_threads() {
426 _cg1r->stop();
427 _czft->stop();
428 _cmThread->stop();
429 }
430
431
432 void G1CollectedHeap::check_ct_logs_at_safepoint() {
433 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
434 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
435
436 // Count the dirty cards at the start.
437 CountNonCleanMemRegionClosure count1(this);
438 ct_bs->mod_card_iterate(&count1);
439 int orig_count = count1.n();
440
441 // First clear the logged cards.
442 ClearLoggedCardTableEntryClosure clear;
443 dcqs.set_closure(&clear);
444 dcqs.apply_closure_to_all_completed_buffers();
445 dcqs.iterate_closure_all_threads(false);
446 clear.print_histo();
447
448 // Now ensure that there's no dirty cards.
449 CountNonCleanMemRegionClosure count2(this);
450 ct_bs->mod_card_iterate(&count2);
451 if (count2.n() != 0) {
452 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
453 count2.n(), orig_count);
454 }
455 guarantee(count2.n() == 0, "Card table should be clean.");
456
457 RedirtyLoggedCardTableEntryClosure redirty;
458 JavaThread::dirty_card_queue_set().set_closure(&redirty);
459 dcqs.apply_closure_to_all_completed_buffers();
460 dcqs.iterate_closure_all_threads(false);
461 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
462 clear.calls(), orig_count);
463 guarantee(redirty.calls() == clear.calls(),
464 "Or else mechanism is broken.");
465
466 CountNonCleanMemRegionClosure count3(this);
467 ct_bs->mod_card_iterate(&count3);
468 if (count3.n() != orig_count) {
469 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
470 orig_count, count3.n());
471 guarantee(count3.n() >= orig_count, "Should have restored them all.");
472 }
473
474 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
475 }
476
477 // Private class members.
478
479 G1CollectedHeap* G1CollectedHeap::_g1h;
480
481 // Private methods.
482
483 // Finds a HeapRegion that can be used to allocate a given size of block.
484
485
486 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
487 bool do_expand,
488 bool zero_filled) {
489 ConcurrentZFThread::note_region_alloc();
490 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
491 if (res == NULL && do_expand) {
492 expand(word_size * HeapWordSize);
493 res = alloc_free_region_from_lists(zero_filled);
494 assert(res == NULL ||
495 (!res->isHumongous() &&
496 (!zero_filled ||
497 res->zero_fill_state() == HeapRegion::Allocated)),
498 "Alloc Regions must be zero filled (and non-H)");
499 }
500 if (res != NULL) {
501 if (res->is_empty()) {
502 _free_regions--;
503 }
504 assert(!res->isHumongous() &&
505 (!zero_filled || res->zero_fill_state() == HeapRegion::Allocated),
506 err_msg("Non-young alloc Regions must be zero filled (and non-H):"
507 " res->isHumongous()=%d, zero_filled=%d, res->zero_fill_state()=%d",
508 res->isHumongous(), zero_filled, res->zero_fill_state()));
509 assert(!res->is_on_unclean_list(),
510 "Alloc Regions must not be on the unclean list");
511 if (G1PrintHeapRegions) {
512 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
513 "top "PTR_FORMAT,
514 res->hrs_index(), res->bottom(), res->end(), res->top());
515 }
516 }
517 return res;
518 }
519
520 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
521 size_t word_size,
522 bool zero_filled) {
523 HeapRegion* alloc_region = NULL;
524 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
525 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
526 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
527 alloc_region->set_survivor();
528 }
529 ++_gc_alloc_region_counts[purpose];
530 } else {
531 g1_policy()->note_alloc_region_limit_reached(purpose);
532 }
533 return alloc_region;
534 }
535
536 // If could fit into free regions w/o expansion, try.
537 // Otherwise, if can expand, do so.
538 // Otherwise, if using ex regions might help, try with ex given back.
539 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
540 assert(regions_accounted_for(), "Region leakage!");
541
542 // We can't allocate H regions while cleanupComplete is running, since
543 // some of the regions we find to be empty might not yet be added to the
544 // unclean list. (If we're already at a safepoint, this call is
545 // unnecessary, not to mention wrong.)
546 if (!SafepointSynchronize::is_at_safepoint())
547 wait_for_cleanup_complete();
548
549 size_t num_regions =
550 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
551
552 // Special case if < one region???
553
554 // Remember the ft size.
555 size_t x_size = expansion_regions();
556
557 HeapWord* res = NULL;
558 bool eliminated_allocated_from_lists = false;
559
560 // Can the allocation potentially fit in the free regions?
561 if (free_regions() >= num_regions) {
562 res = _hrs->obj_allocate(word_size);
563 }
564 if (res == NULL) {
565 // Try expansion.
566 size_t fs = _hrs->free_suffix();
567 if (fs + x_size >= num_regions) {
568 expand((num_regions - fs) * HeapRegion::GrainBytes);
569 res = _hrs->obj_allocate(word_size);
570 assert(res != NULL, "This should have worked.");
571 } else {
572 // Expansion won't help. Are there enough free regions if we get rid
573 // of reservations?
574 size_t avail = free_regions();
575 if (avail >= num_regions) {
576 res = _hrs->obj_allocate(word_size);
577 if (res != NULL) {
578 remove_allocated_regions_from_lists();
579 eliminated_allocated_from_lists = true;
580 }
581 }
582 }
583 }
584 if (res != NULL) {
585 // Increment by the number of regions allocated.
586 // FIXME: Assumes regions all of size GrainBytes.
587 #ifndef PRODUCT
588 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
589 HeapRegion::GrainWords));
590 #endif
591 if (!eliminated_allocated_from_lists)
592 remove_allocated_regions_from_lists();
593 _summary_bytes_used += word_size * HeapWordSize;
594 _free_regions -= num_regions;
595 _num_humongous_regions += (int) num_regions;
596 }
597 assert(regions_accounted_for(), "Region Leakage");
598 return res;
599 }
600
601 HeapWord*
602 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
603 bool permit_collection_pause) {
604 HeapWord* res = NULL;
605 HeapRegion* allocated_young_region = NULL;
606
607 assert( SafepointSynchronize::is_at_safepoint() ||
608 Heap_lock->owned_by_self(), "pre condition of the call" );
609
610 if (isHumongous(word_size)) {
611 // Allocation of a humongous object can, in a sense, complete a
612 // partial region, if the previous alloc was also humongous, and
613 // caused the test below to succeed.
614 if (permit_collection_pause)
615 do_collection_pause_if_appropriate(word_size);
616 res = humongousObjAllocate(word_size);
617 assert(_cur_alloc_region == NULL
618 || !_cur_alloc_region->isHumongous(),
619 "Prevent a regression of this bug.");
620
621 } else {
622 // We may have concurrent cleanup working at the time. Wait for it
623 // to complete. In the future we would probably want to make the
624 // concurrent cleanup truly concurrent by decoupling it from the
625 // allocation.
626 if (!SafepointSynchronize::is_at_safepoint())
627 wait_for_cleanup_complete();
628 // If we do a collection pause, this will be reset to a non-NULL
629 // value. If we don't, nulling here ensures that we allocate a new
630 // region below.
631 if (_cur_alloc_region != NULL) {
632 // We're finished with the _cur_alloc_region.
633 // As we're builing (at least the young portion) of the collection
634 // set incrementally we'll add the current allocation region to
635 // the collection set here.
636 if (_cur_alloc_region->is_young()) {
637 g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
638 }
639 _summary_bytes_used += _cur_alloc_region->used();
640 _cur_alloc_region = NULL;
641 }
642 assert(_cur_alloc_region == NULL, "Invariant.");
643 // Completion of a heap region is perhaps a good point at which to do
644 // a collection pause.
645 if (permit_collection_pause)
646 do_collection_pause_if_appropriate(word_size);
647 // Make sure we have an allocation region available.
648 if (_cur_alloc_region == NULL) {
649 if (!SafepointSynchronize::is_at_safepoint())
650 wait_for_cleanup_complete();
651 bool next_is_young = should_set_young_locked();
652 // If the next region is not young, make sure it's zero-filled.
653 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
654 if (_cur_alloc_region != NULL) {
655 _summary_bytes_used -= _cur_alloc_region->used();
656 if (next_is_young) {
657 set_region_short_lived_locked(_cur_alloc_region);
658 allocated_young_region = _cur_alloc_region;
659 }
660 }
661 }
662 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
663 "Prevent a regression of this bug.");
664
665 // Now retry the allocation.
666 if (_cur_alloc_region != NULL) {
667 if (allocated_young_region != NULL) {
668 // We need to ensure that the store to top does not
669 // float above the setting of the young type.
670 OrderAccess::storestore();
671 }
672 res = _cur_alloc_region->allocate(word_size);
673 }
674 }
675
676 // NOTE: fails frequently in PRT
677 assert(regions_accounted_for(), "Region leakage!");
678
679 if (res != NULL) {
680 if (!SafepointSynchronize::is_at_safepoint()) {
681 assert( permit_collection_pause, "invariant" );
682 assert( Heap_lock->owned_by_self(), "invariant" );
683 Heap_lock->unlock();
684 }
685
686 if (allocated_young_region != NULL) {
687 HeapRegion* hr = allocated_young_region;
688 HeapWord* bottom = hr->bottom();
689 HeapWord* end = hr->end();
690 MemRegion mr(bottom, end);
691 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
692 }
693 }
694
695 assert( SafepointSynchronize::is_at_safepoint() ||
696 (res == NULL && Heap_lock->owned_by_self()) ||
697 (res != NULL && !Heap_lock->owned_by_self()),
698 "post condition of the call" );
699
700 return res;
701 }
702
703 HeapWord*
704 G1CollectedHeap::mem_allocate(size_t word_size,
705 bool is_noref,
706 bool is_tlab,
707 bool* gc_overhead_limit_was_exceeded) {
708 debug_only(check_for_valid_allocation_state());
709 assert(no_gc_in_progress(), "Allocation during gc not allowed");
710 HeapWord* result = NULL;
711
712 // Loop until the allocation is satisified,
713 // or unsatisfied after GC.
714 for (int try_count = 1; /* return or throw */; try_count += 1) {
715 int gc_count_before;
716 {
717 Heap_lock->lock();
718 result = attempt_allocation(word_size);
719 if (result != NULL) {
720 // attempt_allocation should have unlocked the heap lock
721 assert(is_in(result), "result not in heap");
722 return result;
723 }
724 // Read the gc count while the heap lock is held.
725 gc_count_before = SharedHeap::heap()->total_collections();
726 Heap_lock->unlock();
727 }
728
729 // Create the garbage collection operation...
730 VM_G1CollectForAllocation op(word_size,
731 gc_count_before);
732
733 // ...and get the VM thread to execute it.
734 VMThread::execute(&op);
735 if (op.prologue_succeeded()) {
736 result = op.result();
737 assert(result == NULL || is_in(result), "result not in heap");
738 return result;
739 }
740
741 // Give a warning if we seem to be looping forever.
742 if ((QueuedAllocationWarningCount > 0) &&
743 (try_count % QueuedAllocationWarningCount == 0)) {
744 warning("G1CollectedHeap::mem_allocate_work retries %d times",
745 try_count);
746 }
747 }
748 }
749
750 void G1CollectedHeap::abandon_cur_alloc_region() {
751 if (_cur_alloc_region != NULL) {
752 // We're finished with the _cur_alloc_region.
753 if (_cur_alloc_region->is_empty()) {
754 _free_regions++;
755 free_region(_cur_alloc_region);
756 } else {
757 // As we're builing (at least the young portion) of the collection
758 // set incrementally we'll add the current allocation region to
759 // the collection set here.
760 if (_cur_alloc_region->is_young()) {
761 g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
762 }
763 _summary_bytes_used += _cur_alloc_region->used();
764 }
765 _cur_alloc_region = NULL;
766 }
767 }
768
769 void G1CollectedHeap::abandon_gc_alloc_regions() {
770 // first, make sure that the GC alloc region list is empty (it should!)
771 assert(_gc_alloc_region_list == NULL, "invariant");
772 release_gc_alloc_regions(true /* totally */);
773 }
774
775 class PostMCRemSetClearClosure: public HeapRegionClosure {
776 ModRefBarrierSet* _mr_bs;
777 public:
778 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
779 bool doHeapRegion(HeapRegion* r) {
780 r->reset_gc_time_stamp();
781 if (r->continuesHumongous())
782 return false;
783 HeapRegionRemSet* hrrs = r->rem_set();
784 if (hrrs != NULL) hrrs->clear();
785 // You might think here that we could clear just the cards
786 // corresponding to the used region. But no: if we leave a dirty card
787 // in a region we might allocate into, then it would prevent that card
788 // from being enqueued, and cause it to be missed.
789 // Re: the performance cost: we shouldn't be doing full GC anyway!
790 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
791 return false;
792 }
793 };
794
795
796 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
797 ModRefBarrierSet* _mr_bs;
798 public:
799 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
800 bool doHeapRegion(HeapRegion* r) {
801 if (r->continuesHumongous()) return false;
802 if (r->used_region().word_size() != 0) {
803 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
804 }
805 return false;
806 }
807 };
808
809 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
810 G1CollectedHeap* _g1h;
811 UpdateRSOopClosure _cl;
812 int _worker_i;
813 public:
814 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
815 _cl(g1->g1_rem_set(), worker_i),
816 _worker_i(worker_i),
817 _g1h(g1)
818 { }
819 bool doHeapRegion(HeapRegion* r) {
820 if (!r->continuesHumongous()) {
821 _cl.set_from(r);
822 r->oop_iterate(&_cl);
823 }
824 return false;
825 }
826 };
827
828 class ParRebuildRSTask: public AbstractGangTask {
829 G1CollectedHeap* _g1;
830 public:
831 ParRebuildRSTask(G1CollectedHeap* g1)
832 : AbstractGangTask("ParRebuildRSTask"),
833 _g1(g1)
834 { }
835
836 void work(int i) {
837 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
838 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
839 HeapRegion::RebuildRSClaimValue);
840 }
841 };
842
843 void G1CollectedHeap::do_collection(bool explicit_gc,
844 bool clear_all_soft_refs,
845 size_t word_size) {
846 if (GC_locker::check_active_before_gc()) {
847 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
848 }
849
850 ResourceMark rm;
851
852 if (PrintHeapAtGC) {
853 Universe::print_heap_before_gc();
854 }
855
856 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
857 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
858
859 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
860 collector_policy()->should_clear_all_soft_refs();
861
862 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
863
864 {
865 IsGCActiveMark x;
866
867 // Timing
868 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
869 assert(!system_gc || explicit_gc, "invariant");
870 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
871 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
872 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
873 PrintGC, true, gclog_or_tty);
874
875 TraceMemoryManagerStats tms(true /* fullGC */);
876
877 double start = os::elapsedTime();
878 g1_policy()->record_full_collection_start();
879
880 gc_prologue(true);
881 increment_total_collections(true /* full gc */);
882
883 size_t g1h_prev_used = used();
884 assert(used() == recalculate_used(), "Should be equal");
885
886 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
887 HandleMark hm; // Discard invalid handles created during verification
888 prepare_for_verify();
889 gclog_or_tty->print(" VerifyBeforeGC:");
890 Universe::verify(true);
891 }
892 assert(regions_accounted_for(), "Region leakage!");
893
894 COMPILER2_PRESENT(DerivedPointerTable::clear());
895
896 // We want to discover references, but not process them yet.
897 // This mode is disabled in
898 // instanceRefKlass::process_discovered_references if the
899 // generation does some collection work, or
900 // instanceRefKlass::enqueue_discovered_references if the
901 // generation returns without doing any work.
902 ref_processor()->disable_discovery();
903 ref_processor()->abandon_partial_discovery();
904 ref_processor()->verify_no_references_recorded();
905
906 // Abandon current iterations of concurrent marking and concurrent
907 // refinement, if any are in progress.
908 concurrent_mark()->abort();
909
910 // Make sure we'll choose a new allocation region afterwards.
911 abandon_cur_alloc_region();
912 abandon_gc_alloc_regions();
913 assert(_cur_alloc_region == NULL, "Invariant.");
914 g1_rem_set()->cleanupHRRS();
915 tear_down_region_lists();
916 set_used_regions_to_need_zero_fill();
917
918 // We may have added regions to the current incremental collection
919 // set between the last GC or pause and now. We need to clear the
920 // incremental collection set and then start rebuilding it afresh
921 // after this full GC.
922 abandon_collection_set(g1_policy()->inc_cset_head());
923 g1_policy()->clear_incremental_cset();
924 g1_policy()->stop_incremental_cset_building();
925
926 if (g1_policy()->in_young_gc_mode()) {
927 empty_young_list();
928 g1_policy()->set_full_young_gcs(true);
929 }
930
931 // Temporarily make reference _discovery_ single threaded (non-MT).
932 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
933
934 // Temporarily make refs discovery atomic
935 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
936
937 // Temporarily clear _is_alive_non_header
938 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
939
940 ref_processor()->enable_discovery();
941 ref_processor()->setup_policy(do_clear_all_soft_refs);
942
943 // Do collection work
944 {
945 HandleMark hm; // Discard invalid handles created during gc
946 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
947 }
948 // Because freeing humongous regions may have added some unclean
949 // regions, it is necessary to tear down again before rebuilding.
950 tear_down_region_lists();
951 rebuild_region_lists();
952
953 _summary_bytes_used = recalculate_used();
954
955 ref_processor()->enqueue_discovered_references();
956
957 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
958
959 MemoryService::track_memory_usage();
960
961 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
962 HandleMark hm; // Discard invalid handles created during verification
963 gclog_or_tty->print(" VerifyAfterGC:");
964 prepare_for_verify();
965 Universe::verify(false);
966 }
967 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
968
969 reset_gc_time_stamp();
970 // Since everything potentially moved, we will clear all remembered
971 // sets, and clear all cards. Later we will rebuild remebered
972 // sets. We will also reset the GC time stamps of the regions.
973 PostMCRemSetClearClosure rs_clear(mr_bs());
974 heap_region_iterate(&rs_clear);
975
976 // Resize the heap if necessary.
977 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
978
979 if (_cg1r->use_cache()) {
980 _cg1r->clear_and_record_card_counts();
981 _cg1r->clear_hot_cache();
982 }
983
984 // Rebuild remembered sets of all regions.
985
986 if (G1CollectedHeap::use_parallel_gc_threads()) {
987 ParRebuildRSTask rebuild_rs_task(this);
988 assert(check_heap_region_claim_values(
989 HeapRegion::InitialClaimValue), "sanity check");
990 set_par_threads(workers()->total_workers());
991 workers()->run_task(&rebuild_rs_task);
992 set_par_threads(0);
993 assert(check_heap_region_claim_values(
994 HeapRegion::RebuildRSClaimValue), "sanity check");
995 reset_heap_region_claim_values();
996 } else {
997 RebuildRSOutOfRegionClosure rebuild_rs(this);
998 heap_region_iterate(&rebuild_rs);
999 }
1000
1001 if (PrintGC) {
1002 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1003 }
1004
1005 if (true) { // FIXME
1006 // Ask the permanent generation to adjust size for full collections
1007 perm()->compute_new_size();
1008 }
1009
1010 // Start a new incremental collection set for the next pause
1011 assert(g1_policy()->collection_set() == NULL, "must be");
1012 g1_policy()->start_incremental_cset_building();
1013
1014 // Clear the _cset_fast_test bitmap in anticipation of adding
1015 // regions to the incremental collection set for the next
1016 // evacuation pause.
1017 clear_cset_fast_test();
1018
1019 double end = os::elapsedTime();
1020 g1_policy()->record_full_collection_end();
1021
1022 #ifdef TRACESPINNING
1023 ParallelTaskTerminator::print_termination_counts();
1024 #endif
1025
1026 gc_epilogue(true);
1027
1028 // Discard all rset updates
1029 JavaThread::dirty_card_queue_set().abandon_logs();
1030 assert(!G1DeferredRSUpdate
1031 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1032 assert(regions_accounted_for(), "Region leakage!");
1033 }
1034
1035 if (g1_policy()->in_young_gc_mode()) {
1036 _young_list->reset_sampled_info();
1037 // At this point there should be no regions in the
1038 // entire heap tagged as young.
1039 assert( check_young_list_empty(true /* check_heap */),
1040 "young list should be empty at this point");
1041 }
1042
1043 // Update the number of full collections that have been completed.
1044 increment_full_collections_completed(false /* outer */);
1045
1046 if (PrintHeapAtGC) {
1047 Universe::print_heap_after_gc();
1048 }
1049 }
1050
1051 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1052 do_collection(true, /* explicit_gc */
1053 clear_all_soft_refs,
1054 0 /* word_size */);
1055 }
1056
1057 // This code is mostly copied from TenuredGeneration.
1058 void
1059 G1CollectedHeap::
1060 resize_if_necessary_after_full_collection(size_t word_size) {
1061 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1062
1063 // Include the current allocation, if any, and bytes that will be
1064 // pre-allocated to support collections, as "used".
1065 const size_t used_after_gc = used();
1066 const size_t capacity_after_gc = capacity();
1067 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1068
1069 // This is enforced in arguments.cpp.
1070 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1071 "otherwise the code below doesn't make sense");
1072
1073 // We don't have floating point command-line arguments
1074 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1075 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1076 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1077 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1078
1079 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1080 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1081
1082 // We have to be careful here as these two calculations can overflow
1083 // 32-bit size_t's.
1084 double used_after_gc_d = (double) used_after_gc;
1085 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1086 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1087
1088 // Let's make sure that they are both under the max heap size, which
1089 // by default will make them fit into a size_t.
1090 double desired_capacity_upper_bound = (double) max_heap_size;
1091 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1092 desired_capacity_upper_bound);
1093 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1094 desired_capacity_upper_bound);
1095
1096 // We can now safely turn them into size_t's.
1097 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1098 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1099
1100 // This assert only makes sense here, before we adjust them
1101 // with respect to the min and max heap size.
1102 assert(minimum_desired_capacity <= maximum_desired_capacity,
1103 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1104 "maximum_desired_capacity = "SIZE_FORMAT,
1105 minimum_desired_capacity, maximum_desired_capacity));
1106
1107 // Should not be greater than the heap max size. No need to adjust
1108 // it with respect to the heap min size as it's a lower bound (i.e.,
1109 // we'll try to make the capacity larger than it, not smaller).
1110 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1111 // Should not be less than the heap min size. No need to adjust it
1112 // with respect to the heap max size as it's an upper bound (i.e.,
1113 // we'll try to make the capacity smaller than it, not greater).
1114 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1115
1116 if (PrintGC && Verbose) {
1117 const double free_percentage =
1118 (double) free_after_gc / (double) capacity_after_gc;
1119 gclog_or_tty->print_cr("Computing new size after full GC ");
1120 gclog_or_tty->print_cr(" "
1121 " minimum_free_percentage: %6.2f",
1122 minimum_free_percentage);
1123 gclog_or_tty->print_cr(" "
1124 " maximum_free_percentage: %6.2f",
1125 maximum_free_percentage);
1126 gclog_or_tty->print_cr(" "
1127 " capacity: %6.1fK"
1128 " minimum_desired_capacity: %6.1fK"
1129 " maximum_desired_capacity: %6.1fK",
1130 (double) capacity_after_gc / (double) K,
1131 (double) minimum_desired_capacity / (double) K,
1132 (double) maximum_desired_capacity / (double) K);
1133 gclog_or_tty->print_cr(" "
1134 " free_after_gc: %6.1fK"
1135 " used_after_gc: %6.1fK",
1136 (double) free_after_gc / (double) K,
1137 (double) used_after_gc / (double) K);
1138 gclog_or_tty->print_cr(" "
1139 " free_percentage: %6.2f",
1140 free_percentage);
1141 }
1142 if (capacity_after_gc < minimum_desired_capacity) {
1143 // Don't expand unless it's significant
1144 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1145 expand(expand_bytes);
1146 if (PrintGC && Verbose) {
1147 gclog_or_tty->print_cr(" "
1148 " expanding:"
1149 " max_heap_size: %6.1fK"
1150 " minimum_desired_capacity: %6.1fK"
1151 " expand_bytes: %6.1fK",
1152 (double) max_heap_size / (double) K,
1153 (double) minimum_desired_capacity / (double) K,
1154 (double) expand_bytes / (double) K);
1155 }
1156
1157 // No expansion, now see if we want to shrink
1158 } else if (capacity_after_gc > maximum_desired_capacity) {
1159 // Capacity too large, compute shrinking size
1160 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1161 shrink(shrink_bytes);
1162 if (PrintGC && Verbose) {
1163 gclog_or_tty->print_cr(" "
1164 " shrinking:"
1165 " min_heap_size: %6.1fK"
1166 " maximum_desired_capacity: %6.1fK"
1167 " shrink_bytes: %6.1fK",
1168 (double) min_heap_size / (double) K,
1169 (double) maximum_desired_capacity / (double) K,
1170 (double) shrink_bytes / (double) K);
1171 }
1172 }
1173 }
1174
1175
1176 HeapWord*
1177 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1178 HeapWord* result = NULL;
1179
1180 // In a G1 heap, we're supposed to keep allocation from failing by
1181 // incremental pauses. Therefore, at least for now, we'll favor
1182 // expansion over collection. (This might change in the future if we can
1183 // do something smarter than full collection to satisfy a failed alloc.)
1184
1185 result = expand_and_allocate(word_size);
1186 if (result != NULL) {
1187 assert(is_in(result), "result not in heap");
1188 return result;
1189 }
1190
1191 // OK, I guess we have to try collection.
1192
1193 do_collection(false, false, word_size);
1194
1195 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1196
1197 if (result != NULL) {
1198 assert(is_in(result), "result not in heap");
1199 return result;
1200 }
1201
1202 // Try collecting soft references.
1203 do_collection(false, true, word_size);
1204 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1205 if (result != NULL) {
1206 assert(is_in(result), "result not in heap");
1207 return result;
1208 }
1209
1210 assert(!collector_policy()->should_clear_all_soft_refs(),
1211 "Flag should have been handled and cleared prior to this point");
1212
1213 // What else? We might try synchronous finalization later. If the total
1214 // space available is large enough for the allocation, then a more
1215 // complete compaction phase than we've tried so far might be
1216 // appropriate.
1217 return NULL;
1218 }
1219
1220 // Attempting to expand the heap sufficiently
1221 // to support an allocation of the given "word_size". If
1222 // successful, perform the allocation and return the address of the
1223 // allocated block, or else "NULL".
1224
1225 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1226 size_t expand_bytes = word_size * HeapWordSize;
1227 if (expand_bytes < MinHeapDeltaBytes) {
1228 expand_bytes = MinHeapDeltaBytes;
1229 }
1230 expand(expand_bytes);
1231 assert(regions_accounted_for(), "Region leakage!");
1232 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1233 return result;
1234 }
1235
1236 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1237 size_t pre_used = 0;
1238 size_t cleared_h_regions = 0;
1239 size_t freed_regions = 0;
1240 UncleanRegionList local_list;
1241 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1242 freed_regions, &local_list);
1243
1244 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1245 &local_list);
1246 return pre_used;
1247 }
1248
1249 void
1250 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1251 size_t& pre_used,
1252 size_t& cleared_h,
1253 size_t& freed_regions,
1254 UncleanRegionList* list,
1255 bool par) {
1256 assert(!hr->continuesHumongous(), "should have filtered these out");
1257 size_t res = 0;
1258 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1259 !hr->is_young()) {
1260 if (G1PolicyVerbose > 0)
1261 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1262 " during cleanup", hr, hr->used());
1263 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1264 }
1265 }
1266
1267 // FIXME: both this and shrink could probably be more efficient by
1268 // doing one "VirtualSpace::expand_by" call rather than several.
1269 void G1CollectedHeap::expand(size_t expand_bytes) {
1270 size_t old_mem_size = _g1_storage.committed_size();
1271 // We expand by a minimum of 1K.
1272 expand_bytes = MAX2(expand_bytes, (size_t)K);
1273 size_t aligned_expand_bytes =
1274 ReservedSpace::page_align_size_up(expand_bytes);
1275 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1276 HeapRegion::GrainBytes);
1277 expand_bytes = aligned_expand_bytes;
1278 while (expand_bytes > 0) {
1279 HeapWord* base = (HeapWord*)_g1_storage.high();
1280 // Commit more storage.
1281 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1282 if (!successful) {
1283 expand_bytes = 0;
1284 } else {
1285 expand_bytes -= HeapRegion::GrainBytes;
1286 // Expand the committed region.
1287 HeapWord* high = (HeapWord*) _g1_storage.high();
1288 _g1_committed.set_end(high);
1289 // Create a new HeapRegion.
1290 MemRegion mr(base, high);
1291 bool is_zeroed = !_g1_max_committed.contains(base);
1292 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1293
1294 // Now update max_committed if necessary.
1295 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1296
1297 // Add it to the HeapRegionSeq.
1298 _hrs->insert(hr);
1299 // Set the zero-fill state, according to whether it's already
1300 // zeroed.
1301 {
1302 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1303 if (is_zeroed) {
1304 hr->set_zero_fill_complete();
1305 put_free_region_on_list_locked(hr);
1306 } else {
1307 hr->set_zero_fill_needed();
1308 put_region_on_unclean_list_locked(hr);
1309 }
1310 }
1311 _free_regions++;
1312 // And we used up an expansion region to create it.
1313 _expansion_regions--;
1314 // Tell the cardtable about it.
1315 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1316 // And the offset table as well.
1317 _bot_shared->resize(_g1_committed.word_size());
1318 }
1319 }
1320 if (Verbose && PrintGC) {
1321 size_t new_mem_size = _g1_storage.committed_size();
1322 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1323 old_mem_size/K, aligned_expand_bytes/K,
1324 new_mem_size/K);
1325 }
1326 }
1327
1328 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1329 {
1330 size_t old_mem_size = _g1_storage.committed_size();
1331 size_t aligned_shrink_bytes =
1332 ReservedSpace::page_align_size_down(shrink_bytes);
1333 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1334 HeapRegion::GrainBytes);
1335 size_t num_regions_deleted = 0;
1336 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1337
1338 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1339 if (mr.byte_size() > 0)
1340 _g1_storage.shrink_by(mr.byte_size());
1341 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1342
1343 _g1_committed.set_end(mr.start());
1344 _free_regions -= num_regions_deleted;
1345 _expansion_regions += num_regions_deleted;
1346
1347 // Tell the cardtable about it.
1348 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1349
1350 // And the offset table as well.
1351 _bot_shared->resize(_g1_committed.word_size());
1352
1353 HeapRegionRemSet::shrink_heap(n_regions());
1354
1355 if (Verbose && PrintGC) {
1356 size_t new_mem_size = _g1_storage.committed_size();
1357 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1358 old_mem_size/K, aligned_shrink_bytes/K,
1359 new_mem_size/K);
1360 }
1361 }
1362
1363 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1364 release_gc_alloc_regions(true /* totally */);
1365 tear_down_region_lists(); // We will rebuild them in a moment.
1366 shrink_helper(shrink_bytes);
1367 rebuild_region_lists();
1368 }
1369
1370 // Public methods.
1371
1372 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1373 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1374 #endif // _MSC_VER
1375
1376
1377 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1378 SharedHeap(policy_),
1379 _g1_policy(policy_),
1380 _dirty_card_queue_set(false),
1381 _into_cset_dirty_card_queue_set(false),
1382 _ref_processor(NULL),
1383 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1384 _bot_shared(NULL),
1385 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1386 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1387 _evac_failure_scan_stack(NULL) ,
1388 _mark_in_progress(false),
1389 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1390 _cur_alloc_region(NULL),
1391 _refine_cte_cl(NULL),
1392 _free_region_list(NULL), _free_region_list_size(0),
1393 _free_regions(0),
1394 _full_collection(false),
1395 _unclean_region_list(),
1396 _unclean_regions_coming(false),
1397 _young_list(new YoungList(this)),
1398 _gc_time_stamp(0),
1399 _surviving_young_words(NULL),
1400 _full_collections_completed(0),
1401 _in_cset_fast_test(NULL),
1402 _in_cset_fast_test_base(NULL),
1403 _dirty_cards_region_list(NULL) {
1404 _g1h = this; // To catch bugs.
1405 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1406 vm_exit_during_initialization("Failed necessary allocation.");
1407 }
1408
1409 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1410
1411 int n_queues = MAX2((int)ParallelGCThreads, 1);
1412 _task_queues = new RefToScanQueueSet(n_queues);
1413
1414 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1415 assert(n_rem_sets > 0, "Invariant.");
1416
1417 HeapRegionRemSetIterator** iter_arr =
1418 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1419 for (int i = 0; i < n_queues; i++) {
1420 iter_arr[i] = new HeapRegionRemSetIterator();
1421 }
1422 _rem_set_iterator = iter_arr;
1423
1424 for (int i = 0; i < n_queues; i++) {
1425 RefToScanQueue* q = new RefToScanQueue();
1426 q->initialize();
1427 _task_queues->register_queue(i, q);
1428 }
1429
1430 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1431 _gc_alloc_regions[ap] = NULL;
1432 _gc_alloc_region_counts[ap] = 0;
1433 _retained_gc_alloc_regions[ap] = NULL;
1434 // by default, we do not retain a GC alloc region for each ap;
1435 // we'll override this, when appropriate, below
1436 _retain_gc_alloc_region[ap] = false;
1437 }
1438
1439 // We will try to remember the last half-full tenured region we
1440 // allocated to at the end of a collection so that we can re-use it
1441 // during the next collection.
1442 _retain_gc_alloc_region[GCAllocForTenured] = true;
1443
1444 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1445 }
1446
1447 jint G1CollectedHeap::initialize() {
1448 CollectedHeap::pre_initialize();
1449 os::enable_vtime();
1450
1451 // Necessary to satisfy locking discipline assertions.
1452
1453 MutexLocker x(Heap_lock);
1454
1455 // While there are no constraints in the GC code that HeapWordSize
1456 // be any particular value, there are multiple other areas in the
1457 // system which believe this to be true (e.g. oop->object_size in some
1458 // cases incorrectly returns the size in wordSize units rather than
1459 // HeapWordSize).
1460 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1461
1462 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1463 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1464
1465 // Ensure that the sizes are properly aligned.
1466 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1467 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1468
1469 _cg1r = new ConcurrentG1Refine();
1470
1471 // Reserve the maximum.
1472 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1473 // Includes the perm-gen.
1474
1475 const size_t total_reserved = max_byte_size + pgs->max_size();
1476 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1477
1478 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1479 HeapRegion::GrainBytes,
1480 false /*ism*/, addr);
1481
1482 if (UseCompressedOops) {
1483 if (addr != NULL && !heap_rs.is_reserved()) {
1484 // Failed to reserve at specified address - the requested memory
1485 // region is taken already, for example, by 'java' launcher.
1486 // Try again to reserver heap higher.
1487 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1488 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1489 false /*ism*/, addr);
1490 if (addr != NULL && !heap_rs0.is_reserved()) {
1491 // Failed to reserve at specified address again - give up.
1492 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1493 assert(addr == NULL, "");
1494 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1495 false /*ism*/, addr);
1496 heap_rs = heap_rs1;
1497 } else {
1498 heap_rs = heap_rs0;
1499 }
1500 }
1501 }
1502
1503 if (!heap_rs.is_reserved()) {
1504 vm_exit_during_initialization("Could not reserve enough space for object heap");
1505 return JNI_ENOMEM;
1506 }
1507
1508 // It is important to do this in a way such that concurrent readers can't
1509 // temporarily think somethings in the heap. (I've actually seen this
1510 // happen in asserts: DLD.)
1511 _reserved.set_word_size(0);
1512 _reserved.set_start((HeapWord*)heap_rs.base());
1513 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1514
1515 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1516
1517 _num_humongous_regions = 0;
1518
1519 // Create the gen rem set (and barrier set) for the entire reserved region.
1520 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1521 set_barrier_set(rem_set()->bs());
1522 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1523 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1524 } else {
1525 vm_exit_during_initialization("G1 requires a mod ref bs.");
1526 return JNI_ENOMEM;
1527 }
1528
1529 // Also create a G1 rem set.
1530 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1531 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1532 } else {
1533 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1534 return JNI_ENOMEM;
1535 }
1536
1537 // Carve out the G1 part of the heap.
1538
1539 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1540 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1541 g1_rs.size()/HeapWordSize);
1542 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1543
1544 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1545
1546 _g1_storage.initialize(g1_rs, 0);
1547 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1548 _g1_max_committed = _g1_committed;
1549 _hrs = new HeapRegionSeq(_expansion_regions);
1550 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1551 guarantee(_cur_alloc_region == NULL, "from constructor");
1552
1553 // 6843694 - ensure that the maximum region index can fit
1554 // in the remembered set structures.
1555 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1556 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1557
1558 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1559 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1560 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1561 "too many cards per region");
1562
1563 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1564 heap_word_size(init_byte_size));
1565
1566 _g1h = this;
1567
1568 _in_cset_fast_test_length = max_regions();
1569 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1570
1571 // We're biasing _in_cset_fast_test to avoid subtracting the
1572 // beginning of the heap every time we want to index; basically
1573 // it's the same with what we do with the card table.
1574 _in_cset_fast_test = _in_cset_fast_test_base -
1575 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1576
1577 // Clear the _cset_fast_test bitmap in anticipation of adding
1578 // regions to the incremental collection set for the first
1579 // evacuation pause.
1580 clear_cset_fast_test();
1581
1582 // Create the ConcurrentMark data structure and thread.
1583 // (Must do this late, so that "max_regions" is defined.)
1584 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1585 _cmThread = _cm->cmThread();
1586
1587 // ...and the concurrent zero-fill thread, if necessary.
1588 if (G1ConcZeroFill) {
1589 _czft = new ConcurrentZFThread();
1590 }
1591
1592 // Initialize the from_card cache structure of HeapRegionRemSet.
1593 HeapRegionRemSet::init_heap(max_regions());
1594
1595 // Now expand into the initial heap size.
1596 expand(init_byte_size);
1597
1598 // Perform any initialization actions delegated to the policy.
1599 g1_policy()->init();
1600
1601 g1_policy()->note_start_of_mark_thread();
1602
1603 _refine_cte_cl =
1604 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1605 g1_rem_set(),
1606 concurrent_g1_refine());
1607 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1608
1609 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1610 SATB_Q_FL_lock,
1611 G1SATBProcessCompletedThreshold,
1612 Shared_SATB_Q_lock);
1613
1614 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1615 DirtyCardQ_FL_lock,
1616 concurrent_g1_refine()->yellow_zone(),
1617 concurrent_g1_refine()->red_zone(),
1618 Shared_DirtyCardQ_lock);
1619
1620 if (G1DeferredRSUpdate) {
1621 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1622 DirtyCardQ_FL_lock,
1623 -1, // never trigger processing
1624 -1, // no limit on length
1625 Shared_DirtyCardQ_lock,
1626 &JavaThread::dirty_card_queue_set());
1627 }
1628
1629 // Initialize the card queue set used to hold cards containing
1630 // references into the collection set.
1631 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
1632 DirtyCardQ_FL_lock,
1633 -1, // never trigger processing
1634 -1, // no limit on length
1635 Shared_DirtyCardQ_lock,
1636 &JavaThread::dirty_card_queue_set());
1637
1638 // In case we're keeping closure specialization stats, initialize those
1639 // counts and that mechanism.
1640 SpecializationStats::clear();
1641
1642 _gc_alloc_region_list = NULL;
1643
1644 // Do later initialization work for concurrent refinement.
1645 _cg1r->init();
1646
1647 return JNI_OK;
1648 }
1649
1650 void G1CollectedHeap::ref_processing_init() {
1651 SharedHeap::ref_processing_init();
1652 MemRegion mr = reserved_region();
1653 _ref_processor = ReferenceProcessor::create_ref_processor(
1654 mr, // span
1655 false, // Reference discovery is not atomic
1656 // (though it shouldn't matter here.)
1657 true, // mt_discovery
1658 NULL, // is alive closure: need to fill this in for efficiency
1659 ParallelGCThreads,
1660 ParallelRefProcEnabled,
1661 true); // Setting next fields of discovered
1662 // lists requires a barrier.
1663 }
1664
1665 size_t G1CollectedHeap::capacity() const {
1666 return _g1_committed.byte_size();
1667 }
1668
1669 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
1670 DirtyCardQueue* into_cset_dcq,
1671 bool concurrent,
1672 int worker_i) {
1673 // Clean cards in the hot card cache
1674 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
1675
1676 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1677 int n_completed_buffers = 0;
1678 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
1679 n_completed_buffers++;
1680 }
1681 g1_policy()->record_update_rs_processed_buffers(worker_i,
1682 (double) n_completed_buffers);
1683 dcqs.clear_n_completed_buffers();
1684 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1685 }
1686
1687
1688 // Computes the sum of the storage used by the various regions.
1689
1690 size_t G1CollectedHeap::used() const {
1691 assert(Heap_lock->owner() != NULL,
1692 "Should be owned on this thread's behalf.");
1693 size_t result = _summary_bytes_used;
1694 // Read only once in case it is set to NULL concurrently
1695 HeapRegion* hr = _cur_alloc_region;
1696 if (hr != NULL)
1697 result += hr->used();
1698 return result;
1699 }
1700
1701 size_t G1CollectedHeap::used_unlocked() const {
1702 size_t result = _summary_bytes_used;
1703 return result;
1704 }
1705
1706 class SumUsedClosure: public HeapRegionClosure {
1707 size_t _used;
1708 public:
1709 SumUsedClosure() : _used(0) {}
1710 bool doHeapRegion(HeapRegion* r) {
1711 if (!r->continuesHumongous()) {
1712 _used += r->used();
1713 }
1714 return false;
1715 }
1716 size_t result() { return _used; }
1717 };
1718
1719 size_t G1CollectedHeap::recalculate_used() const {
1720 SumUsedClosure blk;
1721 _hrs->iterate(&blk);
1722 return blk.result();
1723 }
1724
1725 #ifndef PRODUCT
1726 class SumUsedRegionsClosure: public HeapRegionClosure {
1727 size_t _num;
1728 public:
1729 SumUsedRegionsClosure() : _num(0) {}
1730 bool doHeapRegion(HeapRegion* r) {
1731 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1732 _num += 1;
1733 }
1734 return false;
1735 }
1736 size_t result() { return _num; }
1737 };
1738
1739 size_t G1CollectedHeap::recalculate_used_regions() const {
1740 SumUsedRegionsClosure blk;
1741 _hrs->iterate(&blk);
1742 return blk.result();
1743 }
1744 #endif // PRODUCT
1745
1746 size_t G1CollectedHeap::unsafe_max_alloc() {
1747 if (_free_regions > 0) return HeapRegion::GrainBytes;
1748 // otherwise, is there space in the current allocation region?
1749
1750 // We need to store the current allocation region in a local variable
1751 // here. The problem is that this method doesn't take any locks and
1752 // there may be other threads which overwrite the current allocation
1753 // region field. attempt_allocation(), for example, sets it to NULL
1754 // and this can happen *after* the NULL check here but before the call
1755 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1756 // to be a problem in the optimized build, since the two loads of the
1757 // current allocation region field are optimized away.
1758 HeapRegion* car = _cur_alloc_region;
1759
1760 // FIXME: should iterate over all regions?
1761 if (car == NULL) {
1762 return 0;
1763 }
1764 return car->free();
1765 }
1766
1767 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1768 return
1769 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
1770 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
1771 }
1772
1773 void G1CollectedHeap::increment_full_collections_completed(bool outer) {
1774 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1775
1776 // We have already incremented _total_full_collections at the start
1777 // of the GC, so total_full_collections() represents how many full
1778 // collections have been started.
1779 unsigned int full_collections_started = total_full_collections();
1780
1781 // Given that this method is called at the end of a Full GC or of a
1782 // concurrent cycle, and those can be nested (i.e., a Full GC can
1783 // interrupt a concurrent cycle), the number of full collections
1784 // completed should be either one (in the case where there was no
1785 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1786 // behind the number of full collections started.
1787
1788 // This is the case for the inner caller, i.e. a Full GC.
1789 assert(outer ||
1790 (full_collections_started == _full_collections_completed + 1) ||
1791 (full_collections_started == _full_collections_completed + 2),
1792 err_msg("for inner caller: full_collections_started = %u "
1793 "is inconsistent with _full_collections_completed = %u",
1794 full_collections_started, _full_collections_completed));
1795
1796 // This is the case for the outer caller, i.e. the concurrent cycle.
1797 assert(!outer ||
1798 (full_collections_started == _full_collections_completed + 1),
1799 err_msg("for outer caller: full_collections_started = %u "
1800 "is inconsistent with _full_collections_completed = %u",
1801 full_collections_started, _full_collections_completed));
1802
1803 _full_collections_completed += 1;
1804
1805 // We need to clear the "in_progress" flag in the CM thread before
1806 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1807 // is set) so that if a waiter requests another System.gc() it doesn't
1808 // incorrectly see that a marking cyle is still in progress.
1809 if (outer) {
1810 _cmThread->clear_in_progress();
1811 }
1812
1813 // This notify_all() will ensure that a thread that called
1814 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1815 // and it's waiting for a full GC to finish will be woken up. It is
1816 // waiting in VM_G1IncCollectionPause::doit_epilogue().
1817 FullGCCount_lock->notify_all();
1818 }
1819
1820 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1821 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1822 assert(Heap_lock->is_locked(), "Precondition#2");
1823 GCCauseSetter gcs(this, cause);
1824 switch (cause) {
1825 case GCCause::_heap_inspection:
1826 case GCCause::_heap_dump: {
1827 HandleMark hm;
1828 do_full_collection(false); // don't clear all soft refs
1829 break;
1830 }
1831 default: // XXX FIX ME
1832 ShouldNotReachHere(); // Unexpected use of this function
1833 }
1834 }
1835
1836 void G1CollectedHeap::collect(GCCause::Cause cause) {
1837 // The caller doesn't have the Heap_lock
1838 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1839
1840 unsigned int gc_count_before;
1841 unsigned int full_gc_count_before;
1842 {
1843 MutexLocker ml(Heap_lock);
1844 // Read the GC count while holding the Heap_lock
1845 gc_count_before = SharedHeap::heap()->total_collections();
1846 full_gc_count_before = SharedHeap::heap()->total_full_collections();
1847
1848 // Don't want to do a GC until cleanup is completed.
1849 wait_for_cleanup_complete();
1850
1851 // We give up heap lock; VMThread::execute gets it back below
1852 }
1853
1854 if (should_do_concurrent_full_gc(cause)) {
1855 // Schedule an initial-mark evacuation pause that will start a
1856 // concurrent cycle.
1857 VM_G1IncCollectionPause op(gc_count_before,
1858 true, /* should_initiate_conc_mark */
1859 g1_policy()->max_pause_time_ms(),
1860 cause);
1861 VMThread::execute(&op);
1862 } else {
1863 if (cause == GCCause::_gc_locker
1864 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1865
1866 // Schedule a standard evacuation pause.
1867 VM_G1IncCollectionPause op(gc_count_before,
1868 false, /* should_initiate_conc_mark */
1869 g1_policy()->max_pause_time_ms(),
1870 cause);
1871 VMThread::execute(&op);
1872 } else {
1873 // Schedule a Full GC.
1874 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
1875 VMThread::execute(&op);
1876 }
1877 }
1878 }
1879
1880 bool G1CollectedHeap::is_in(const void* p) const {
1881 if (_g1_committed.contains(p)) {
1882 HeapRegion* hr = _hrs->addr_to_region(p);
1883 return hr->is_in(p);
1884 } else {
1885 return _perm_gen->as_gen()->is_in(p);
1886 }
1887 }
1888
1889 // Iteration functions.
1890
1891 // Iterates an OopClosure over all ref-containing fields of objects
1892 // within a HeapRegion.
1893
1894 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1895 MemRegion _mr;
1896 OopClosure* _cl;
1897 public:
1898 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1899 : _mr(mr), _cl(cl) {}
1900 bool doHeapRegion(HeapRegion* r) {
1901 if (! r->continuesHumongous()) {
1902 r->oop_iterate(_cl);
1903 }
1904 return false;
1905 }
1906 };
1907
1908 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1909 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1910 _hrs->iterate(&blk);
1911 if (do_perm) {
1912 perm_gen()->oop_iterate(cl);
1913 }
1914 }
1915
1916 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1917 IterateOopClosureRegionClosure blk(mr, cl);
1918 _hrs->iterate(&blk);
1919 if (do_perm) {
1920 perm_gen()->oop_iterate(cl);
1921 }
1922 }
1923
1924 // Iterates an ObjectClosure over all objects within a HeapRegion.
1925
1926 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1927 ObjectClosure* _cl;
1928 public:
1929 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1930 bool doHeapRegion(HeapRegion* r) {
1931 if (! r->continuesHumongous()) {
1932 r->object_iterate(_cl);
1933 }
1934 return false;
1935 }
1936 };
1937
1938 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1939 IterateObjectClosureRegionClosure blk(cl);
1940 _hrs->iterate(&blk);
1941 if (do_perm) {
1942 perm_gen()->object_iterate(cl);
1943 }
1944 }
1945
1946 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1947 // FIXME: is this right?
1948 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1949 }
1950
1951 // Calls a SpaceClosure on a HeapRegion.
1952
1953 class SpaceClosureRegionClosure: public HeapRegionClosure {
1954 SpaceClosure* _cl;
1955 public:
1956 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1957 bool doHeapRegion(HeapRegion* r) {
1958 _cl->do_space(r);
1959 return false;
1960 }
1961 };
1962
1963 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1964 SpaceClosureRegionClosure blk(cl);
1965 _hrs->iterate(&blk);
1966 }
1967
1968 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1969 _hrs->iterate(cl);
1970 }
1971
1972 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1973 HeapRegionClosure* cl) {
1974 _hrs->iterate_from(r, cl);
1975 }
1976
1977 void
1978 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1979 _hrs->iterate_from(idx, cl);
1980 }
1981
1982 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1983
1984 void
1985 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1986 int worker,
1987 jint claim_value) {
1988 const size_t regions = n_regions();
1989 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
1990 // try to spread out the starting points of the workers
1991 const size_t start_index = regions / worker_num * (size_t) worker;
1992
1993 // each worker will actually look at all regions
1994 for (size_t count = 0; count < regions; ++count) {
1995 const size_t index = (start_index + count) % regions;
1996 assert(0 <= index && index < regions, "sanity");
1997 HeapRegion* r = region_at(index);
1998 // we'll ignore "continues humongous" regions (we'll process them
1999 // when we come across their corresponding "start humongous"
2000 // region) and regions already claimed
2001 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2002 continue;
2003 }
2004 // OK, try to claim it
2005 if (r->claimHeapRegion(claim_value)) {
2006 // success!
2007 assert(!r->continuesHumongous(), "sanity");
2008 if (r->startsHumongous()) {
2009 // If the region is "starts humongous" we'll iterate over its
2010 // "continues humongous" first; in fact we'll do them
2011 // first. The order is important. In on case, calling the
2012 // closure on the "starts humongous" region might de-allocate
2013 // and clear all its "continues humongous" regions and, as a
2014 // result, we might end up processing them twice. So, we'll do
2015 // them first (notice: most closures will ignore them anyway) and
2016 // then we'll do the "starts humongous" region.
2017 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2018 HeapRegion* chr = region_at(ch_index);
2019
2020 // if the region has already been claimed or it's not
2021 // "continues humongous" we're done
2022 if (chr->claim_value() == claim_value ||
2023 !chr->continuesHumongous()) {
2024 break;
2025 }
2026
2027 // Noone should have claimed it directly. We can given
2028 // that we claimed its "starts humongous" region.
2029 assert(chr->claim_value() != claim_value, "sanity");
2030 assert(chr->humongous_start_region() == r, "sanity");
2031
2032 if (chr->claimHeapRegion(claim_value)) {
2033 // we should always be able to claim it; noone else should
2034 // be trying to claim this region
2035
2036 bool res2 = cl->doHeapRegion(chr);
2037 assert(!res2, "Should not abort");
2038
2039 // Right now, this holds (i.e., no closure that actually
2040 // does something with "continues humongous" regions
2041 // clears them). We might have to weaken it in the future,
2042 // but let's leave these two asserts here for extra safety.
2043 assert(chr->continuesHumongous(), "should still be the case");
2044 assert(chr->humongous_start_region() == r, "sanity");
2045 } else {
2046 guarantee(false, "we should not reach here");
2047 }
2048 }
2049 }
2050
2051 assert(!r->continuesHumongous(), "sanity");
2052 bool res = cl->doHeapRegion(r);
2053 assert(!res, "Should not abort");
2054 }
2055 }
2056 }
2057
2058 class ResetClaimValuesClosure: public HeapRegionClosure {
2059 public:
2060 bool doHeapRegion(HeapRegion* r) {
2061 r->set_claim_value(HeapRegion::InitialClaimValue);
2062 return false;
2063 }
2064 };
2065
2066 void
2067 G1CollectedHeap::reset_heap_region_claim_values() {
2068 ResetClaimValuesClosure blk;
2069 heap_region_iterate(&blk);
2070 }
2071
2072 #ifdef ASSERT
2073 // This checks whether all regions in the heap have the correct claim
2074 // value. I also piggy-backed on this a check to ensure that the
2075 // humongous_start_region() information on "continues humongous"
2076 // regions is correct.
2077
2078 class CheckClaimValuesClosure : public HeapRegionClosure {
2079 private:
2080 jint _claim_value;
2081 size_t _failures;
2082 HeapRegion* _sh_region;
2083 public:
2084 CheckClaimValuesClosure(jint claim_value) :
2085 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2086 bool doHeapRegion(HeapRegion* r) {
2087 if (r->claim_value() != _claim_value) {
2088 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2089 "claim value = %d, should be %d",
2090 r->bottom(), r->end(), r->claim_value(),
2091 _claim_value);
2092 ++_failures;
2093 }
2094 if (!r->isHumongous()) {
2095 _sh_region = NULL;
2096 } else if (r->startsHumongous()) {
2097 _sh_region = r;
2098 } else if (r->continuesHumongous()) {
2099 if (r->humongous_start_region() != _sh_region) {
2100 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2101 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2102 r->bottom(), r->end(),
2103 r->humongous_start_region(),
2104 _sh_region);
2105 ++_failures;
2106 }
2107 }
2108 return false;
2109 }
2110 size_t failures() {
2111 return _failures;
2112 }
2113 };
2114
2115 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2116 CheckClaimValuesClosure cl(claim_value);
2117 heap_region_iterate(&cl);
2118 return cl.failures() == 0;
2119 }
2120 #endif // ASSERT
2121
2122 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2123 HeapRegion* r = g1_policy()->collection_set();
2124 while (r != NULL) {
2125 HeapRegion* next = r->next_in_collection_set();
2126 if (cl->doHeapRegion(r)) {
2127 cl->incomplete();
2128 return;
2129 }
2130 r = next;
2131 }
2132 }
2133
2134 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2135 HeapRegionClosure *cl) {
2136 if (r == NULL) {
2137 // The CSet is empty so there's nothing to do.
2138 return;
2139 }
2140
2141 assert(r->in_collection_set(),
2142 "Start region must be a member of the collection set.");
2143 HeapRegion* cur = r;
2144 while (cur != NULL) {
2145 HeapRegion* next = cur->next_in_collection_set();
2146 if (cl->doHeapRegion(cur) && false) {
2147 cl->incomplete();
2148 return;
2149 }
2150 cur = next;
2151 }
2152 cur = g1_policy()->collection_set();
2153 while (cur != r) {
2154 HeapRegion* next = cur->next_in_collection_set();
2155 if (cl->doHeapRegion(cur) && false) {
2156 cl->incomplete();
2157 return;
2158 }
2159 cur = next;
2160 }
2161 }
2162
2163 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2164 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2165 }
2166
2167
2168 Space* G1CollectedHeap::space_containing(const void* addr) const {
2169 Space* res = heap_region_containing(addr);
2170 if (res == NULL)
2171 res = perm_gen()->space_containing(addr);
2172 return res;
2173 }
2174
2175 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2176 Space* sp = space_containing(addr);
2177 if (sp != NULL) {
2178 return sp->block_start(addr);
2179 }
2180 return NULL;
2181 }
2182
2183 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2184 Space* sp = space_containing(addr);
2185 assert(sp != NULL, "block_size of address outside of heap");
2186 return sp->block_size(addr);
2187 }
2188
2189 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2190 Space* sp = space_containing(addr);
2191 return sp->block_is_obj(addr);
2192 }
2193
2194 bool G1CollectedHeap::supports_tlab_allocation() const {
2195 return true;
2196 }
2197
2198 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2199 return HeapRegion::GrainBytes;
2200 }
2201
2202 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2203 // Return the remaining space in the cur alloc region, but not less than
2204 // the min TLAB size.
2205
2206 // Also, this value can be at most the humongous object threshold,
2207 // since we can't allow tlabs to grow big enough to accomodate
2208 // humongous objects.
2209
2210 // We need to store the cur alloc region locally, since it might change
2211 // between when we test for NULL and when we use it later.
2212 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2213 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2214
2215 if (cur_alloc_space == NULL) {
2216 return max_tlab_size;
2217 } else {
2218 return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize),
2219 max_tlab_size);
2220 }
2221 }
2222
2223 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
2224 assert(!isHumongous(word_size),
2225 err_msg("a TLAB should not be of humongous size, "
2226 "word_size = "SIZE_FORMAT, word_size));
2227 bool dummy;
2228 return G1CollectedHeap::mem_allocate(word_size, false, true, &dummy);
2229 }
2230
2231 bool G1CollectedHeap::allocs_are_zero_filled() {
2232 return false;
2233 }
2234
2235 size_t G1CollectedHeap::large_typearray_limit() {
2236 // FIXME
2237 return HeapRegion::GrainBytes/HeapWordSize;
2238 }
2239
2240 size_t G1CollectedHeap::max_capacity() const {
2241 return g1_reserved_obj_bytes();
2242 }
2243
2244 jlong G1CollectedHeap::millis_since_last_gc() {
2245 // assert(false, "NYI");
2246 return 0;
2247 }
2248
2249
2250 void G1CollectedHeap::prepare_for_verify() {
2251 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2252 ensure_parsability(false);
2253 }
2254 g1_rem_set()->prepare_for_verify();
2255 }
2256
2257 class VerifyLivenessOopClosure: public OopClosure {
2258 G1CollectedHeap* g1h;
2259 public:
2260 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2261 g1h = _g1h;
2262 }
2263 void do_oop(narrowOop *p) { do_oop_work(p); }
2264 void do_oop( oop *p) { do_oop_work(p); }
2265
2266 template <class T> void do_oop_work(T *p) {
2267 oop obj = oopDesc::load_decode_heap_oop(p);
2268 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2269 "Dead object referenced by a not dead object");
2270 }
2271 };
2272
2273 class VerifyObjsInRegionClosure: public ObjectClosure {
2274 private:
2275 G1CollectedHeap* _g1h;
2276 size_t _live_bytes;
2277 HeapRegion *_hr;
2278 bool _use_prev_marking;
2279 public:
2280 // use_prev_marking == true -> use "prev" marking information,
2281 // use_prev_marking == false -> use "next" marking information
2282 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2283 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2284 _g1h = G1CollectedHeap::heap();
2285 }
2286 void do_object(oop o) {
2287 VerifyLivenessOopClosure isLive(_g1h);
2288 assert(o != NULL, "Huh?");
2289 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2290 o->oop_iterate(&isLive);
2291 if (!_hr->obj_allocated_since_prev_marking(o)) {
2292 size_t obj_size = o->size(); // Make sure we don't overflow
2293 _live_bytes += (obj_size * HeapWordSize);
2294 }
2295 }
2296 }
2297 size_t live_bytes() { return _live_bytes; }
2298 };
2299
2300 class PrintObjsInRegionClosure : public ObjectClosure {
2301 HeapRegion *_hr;
2302 G1CollectedHeap *_g1;
2303 public:
2304 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2305 _g1 = G1CollectedHeap::heap();
2306 };
2307
2308 void do_object(oop o) {
2309 if (o != NULL) {
2310 HeapWord *start = (HeapWord *) o;
2311 size_t word_sz = o->size();
2312 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2313 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2314 (void*) o, word_sz,
2315 _g1->isMarkedPrev(o),
2316 _g1->isMarkedNext(o),
2317 _hr->obj_allocated_since_prev_marking(o));
2318 HeapWord *end = start + word_sz;
2319 HeapWord *cur;
2320 int *val;
2321 for (cur = start; cur < end; cur++) {
2322 val = (int *) cur;
2323 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2324 }
2325 }
2326 }
2327 };
2328
2329 class VerifyRegionClosure: public HeapRegionClosure {
2330 private:
2331 bool _allow_dirty;
2332 bool _par;
2333 bool _use_prev_marking;
2334 bool _failures;
2335 public:
2336 // use_prev_marking == true -> use "prev" marking information,
2337 // use_prev_marking == false -> use "next" marking information
2338 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2339 : _allow_dirty(allow_dirty),
2340 _par(par),
2341 _use_prev_marking(use_prev_marking),
2342 _failures(false) {}
2343
2344 bool failures() {
2345 return _failures;
2346 }
2347
2348 bool doHeapRegion(HeapRegion* r) {
2349 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2350 "Should be unclaimed at verify points.");
2351 if (!r->continuesHumongous()) {
2352 bool failures = false;
2353 r->verify(_allow_dirty, _use_prev_marking, &failures);
2354 if (failures) {
2355 _failures = true;
2356 } else {
2357 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2358 r->object_iterate(¬_dead_yet_cl);
2359 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2360 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2361 "max_live_bytes "SIZE_FORMAT" "
2362 "< calculated "SIZE_FORMAT,
2363 r->bottom(), r->end(),
2364 r->max_live_bytes(),
2365 not_dead_yet_cl.live_bytes());
2366 _failures = true;
2367 }
2368 }
2369 }
2370 return false; // stop the region iteration if we hit a failure
2371 }
2372 };
2373
2374 class VerifyRootsClosure: public OopsInGenClosure {
2375 private:
2376 G1CollectedHeap* _g1h;
2377 bool _use_prev_marking;
2378 bool _failures;
2379 public:
2380 // use_prev_marking == true -> use "prev" marking information,
2381 // use_prev_marking == false -> use "next" marking information
2382 VerifyRootsClosure(bool use_prev_marking) :
2383 _g1h(G1CollectedHeap::heap()),
2384 _use_prev_marking(use_prev_marking),
2385 _failures(false) { }
2386
2387 bool failures() { return _failures; }
2388
2389 template <class T> void do_oop_nv(T* p) {
2390 T heap_oop = oopDesc::load_heap_oop(p);
2391 if (!oopDesc::is_null(heap_oop)) {
2392 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2393 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2394 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2395 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2396 obj->print_on(gclog_or_tty);
2397 _failures = true;
2398 }
2399 }
2400 }
2401
2402 void do_oop(oop* p) { do_oop_nv(p); }
2403 void do_oop(narrowOop* p) { do_oop_nv(p); }
2404 };
2405
2406 // This is the task used for parallel heap verification.
2407
2408 class G1ParVerifyTask: public AbstractGangTask {
2409 private:
2410 G1CollectedHeap* _g1h;
2411 bool _allow_dirty;
2412 bool _use_prev_marking;
2413 bool _failures;
2414
2415 public:
2416 // use_prev_marking == true -> use "prev" marking information,
2417 // use_prev_marking == false -> use "next" marking information
2418 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2419 bool use_prev_marking) :
2420 AbstractGangTask("Parallel verify task"),
2421 _g1h(g1h),
2422 _allow_dirty(allow_dirty),
2423 _use_prev_marking(use_prev_marking),
2424 _failures(false) { }
2425
2426 bool failures() {
2427 return _failures;
2428 }
2429
2430 void work(int worker_i) {
2431 HandleMark hm;
2432 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2433 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2434 HeapRegion::ParVerifyClaimValue);
2435 if (blk.failures()) {
2436 _failures = true;
2437 }
2438 }
2439 };
2440
2441 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2442 verify(allow_dirty, silent, /* use_prev_marking */ true);
2443 }
2444
2445 void G1CollectedHeap::verify(bool allow_dirty,
2446 bool silent,
2447 bool use_prev_marking) {
2448 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2449 if (!silent) { gclog_or_tty->print("roots "); }
2450 VerifyRootsClosure rootsCl(use_prev_marking);
2451 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2452 process_strong_roots(true, // activate StrongRootsScope
2453 false,
2454 SharedHeap::SO_AllClasses,
2455 &rootsCl,
2456 &blobsCl,
2457 &rootsCl);
2458 bool failures = rootsCl.failures();
2459 rem_set()->invalidate(perm_gen()->used_region(), false);
2460 if (!silent) { gclog_or_tty->print("heapRegions "); }
2461 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2462 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2463 "sanity check");
2464
2465 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2466 int n_workers = workers()->total_workers();
2467 set_par_threads(n_workers);
2468 workers()->run_task(&task);
2469 set_par_threads(0);
2470 if (task.failures()) {
2471 failures = true;
2472 }
2473
2474 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2475 "sanity check");
2476
2477 reset_heap_region_claim_values();
2478
2479 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2480 "sanity check");
2481 } else {
2482 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2483 _hrs->iterate(&blk);
2484 if (blk.failures()) {
2485 failures = true;
2486 }
2487 }
2488 if (!silent) gclog_or_tty->print("remset ");
2489 rem_set()->verify();
2490
2491 if (failures) {
2492 gclog_or_tty->print_cr("Heap:");
2493 print_on(gclog_or_tty, true /* extended */);
2494 gclog_or_tty->print_cr("");
2495 #ifndef PRODUCT
2496 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2497 concurrent_mark()->print_reachable("at-verification-failure",
2498 use_prev_marking, false /* all */);
2499 }
2500 #endif
2501 gclog_or_tty->flush();
2502 }
2503 guarantee(!failures, "there should not have been any failures");
2504 } else {
2505 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2506 }
2507 }
2508
2509 class PrintRegionClosure: public HeapRegionClosure {
2510 outputStream* _st;
2511 public:
2512 PrintRegionClosure(outputStream* st) : _st(st) {}
2513 bool doHeapRegion(HeapRegion* r) {
2514 r->print_on(_st);
2515 return false;
2516 }
2517 };
2518
2519 void G1CollectedHeap::print() const { print_on(tty); }
2520
2521 void G1CollectedHeap::print_on(outputStream* st) const {
2522 print_on(st, PrintHeapAtGCExtended);
2523 }
2524
2525 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2526 st->print(" %-20s", "garbage-first heap");
2527 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2528 capacity()/K, used_unlocked()/K);
2529 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2530 _g1_storage.low_boundary(),
2531 _g1_storage.high(),
2532 _g1_storage.high_boundary());
2533 st->cr();
2534 st->print(" region size " SIZE_FORMAT "K, ",
2535 HeapRegion::GrainBytes/K);
2536 size_t young_regions = _young_list->length();
2537 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2538 young_regions, young_regions * HeapRegion::GrainBytes / K);
2539 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2540 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2541 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2542 st->cr();
2543 perm()->as_gen()->print_on(st);
2544 if (extended) {
2545 st->cr();
2546 print_on_extended(st);
2547 }
2548 }
2549
2550 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2551 PrintRegionClosure blk(st);
2552 _hrs->iterate(&blk);
2553 }
2554
2555 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2556 if (G1CollectedHeap::use_parallel_gc_threads()) {
2557 workers()->print_worker_threads_on(st);
2558 }
2559
2560 _cmThread->print_on(st);
2561 st->cr();
2562
2563 _cm->print_worker_threads_on(st);
2564
2565 _cg1r->print_worker_threads_on(st);
2566
2567 _czft->print_on(st);
2568 st->cr();
2569 }
2570
2571 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2572 if (G1CollectedHeap::use_parallel_gc_threads()) {
2573 workers()->threads_do(tc);
2574 }
2575 tc->do_thread(_cmThread);
2576 _cg1r->threads_do(tc);
2577 tc->do_thread(_czft);
2578 }
2579
2580 void G1CollectedHeap::print_tracing_info() const {
2581 // We'll overload this to mean "trace GC pause statistics."
2582 if (TraceGen0Time || TraceGen1Time) {
2583 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2584 // to that.
2585 g1_policy()->print_tracing_info();
2586 }
2587 if (G1SummarizeRSetStats) {
2588 g1_rem_set()->print_summary_info();
2589 }
2590 if (G1SummarizeConcMark) {
2591 concurrent_mark()->print_summary_info();
2592 }
2593 if (G1SummarizeZFStats) {
2594 ConcurrentZFThread::print_summary_info();
2595 }
2596 g1_policy()->print_yg_surv_rate_info();
2597
2598 SpecializationStats::print();
2599 }
2600
2601
2602 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2603 HeapRegion* hr = heap_region_containing(addr);
2604 if (hr == NULL) {
2605 return 0;
2606 } else {
2607 return 1;
2608 }
2609 }
2610
2611 G1CollectedHeap* G1CollectedHeap::heap() {
2612 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2613 "not a garbage-first heap");
2614 return _g1h;
2615 }
2616
2617 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2618 // always_do_update_barrier = false;
2619 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2620 // Call allocation profiler
2621 AllocationProfiler::iterate_since_last_gc();
2622 // Fill TLAB's and such
2623 ensure_parsability(true);
2624 }
2625
2626 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2627 // FIXME: what is this about?
2628 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2629 // is set.
2630 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2631 "derived pointer present"));
2632 // always_do_update_barrier = true;
2633 }
2634
2635 void G1CollectedHeap::do_collection_pause() {
2636 assert(Heap_lock->owned_by_self(), "we assume we'reholding the Heap_lock");
2637
2638 // Read the GC count while holding the Heap_lock
2639 // we need to do this _before_ wait_for_cleanup_complete(), to
2640 // ensure that we do not give up the heap lock and potentially
2641 // pick up the wrong count
2642 unsigned int gc_count_before = SharedHeap::heap()->total_collections();
2643
2644 // Don't want to do a GC pause while cleanup is being completed!
2645 wait_for_cleanup_complete();
2646
2647 g1_policy()->record_stop_world_start();
2648 {
2649 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2650 VM_G1IncCollectionPause op(gc_count_before,
2651 false, /* should_initiate_conc_mark */
2652 g1_policy()->max_pause_time_ms(),
2653 GCCause::_g1_inc_collection_pause);
2654 VMThread::execute(&op);
2655 }
2656 }
2657
2658 void
2659 G1CollectedHeap::doConcurrentMark() {
2660 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2661 if (!_cmThread->in_progress()) {
2662 _cmThread->set_started();
2663 CGC_lock->notify();
2664 }
2665 }
2666
2667 class VerifyMarkedObjsClosure: public ObjectClosure {
2668 G1CollectedHeap* _g1h;
2669 public:
2670 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2671 void do_object(oop obj) {
2672 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2673 "markandsweep mark should agree with concurrent deadness");
2674 }
2675 };
2676
2677 void
2678 G1CollectedHeap::checkConcurrentMark() {
2679 VerifyMarkedObjsClosure verifycl(this);
2680 // MutexLockerEx x(getMarkBitMapLock(),
2681 // Mutex::_no_safepoint_check_flag);
2682 object_iterate(&verifycl, false);
2683 }
2684
2685 void G1CollectedHeap::do_sync_mark() {
2686 _cm->checkpointRootsInitial();
2687 _cm->markFromRoots();
2688 _cm->checkpointRootsFinal(false);
2689 }
2690
2691 // <NEW PREDICTION>
2692
2693 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2694 bool young) {
2695 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2696 }
2697
2698 void G1CollectedHeap::check_if_region_is_too_expensive(double
2699 predicted_time_ms) {
2700 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2701 }
2702
2703 size_t G1CollectedHeap::pending_card_num() {
2704 size_t extra_cards = 0;
2705 JavaThread *curr = Threads::first();
2706 while (curr != NULL) {
2707 DirtyCardQueue& dcq = curr->dirty_card_queue();
2708 extra_cards += dcq.size();
2709 curr = curr->next();
2710 }
2711 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2712 size_t buffer_size = dcqs.buffer_size();
2713 size_t buffer_num = dcqs.completed_buffers_num();
2714 return buffer_size * buffer_num + extra_cards;
2715 }
2716
2717 size_t G1CollectedHeap::max_pending_card_num() {
2718 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2719 size_t buffer_size = dcqs.buffer_size();
2720 size_t buffer_num = dcqs.completed_buffers_num();
2721 int thread_num = Threads::number_of_threads();
2722 return (buffer_num + thread_num) * buffer_size;
2723 }
2724
2725 size_t G1CollectedHeap::cards_scanned() {
2726 return g1_rem_set()->cardsScanned();
2727 }
2728
2729 void
2730 G1CollectedHeap::setup_surviving_young_words() {
2731 guarantee( _surviving_young_words == NULL, "pre-condition" );
2732 size_t array_length = g1_policy()->young_cset_length();
2733 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2734 if (_surviving_young_words == NULL) {
2735 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2736 "Not enough space for young surv words summary.");
2737 }
2738 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2739 #ifdef ASSERT
2740 for (size_t i = 0; i < array_length; ++i) {
2741 assert( _surviving_young_words[i] == 0, "memset above" );
2742 }
2743 #endif // !ASSERT
2744 }
2745
2746 void
2747 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2748 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2749 size_t array_length = g1_policy()->young_cset_length();
2750 for (size_t i = 0; i < array_length; ++i)
2751 _surviving_young_words[i] += surv_young_words[i];
2752 }
2753
2754 void
2755 G1CollectedHeap::cleanup_surviving_young_words() {
2756 guarantee( _surviving_young_words != NULL, "pre-condition" );
2757 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2758 _surviving_young_words = NULL;
2759 }
2760
2761 // </NEW PREDICTION>
2762
2763 struct PrepareForRSScanningClosure : public HeapRegionClosure {
2764 bool doHeapRegion(HeapRegion *r) {
2765 r->rem_set()->set_iter_claimed(0);
2766 return false;
2767 }
2768 };
2769
2770 #if TASKQUEUE_STATS
2771 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2772 st->print_raw_cr("GC Task Stats");
2773 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2774 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2775 }
2776
2777 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
2778 print_taskqueue_stats_hdr(st);
2779
2780 TaskQueueStats totals;
2781 const int n = workers() != NULL ? workers()->total_workers() : 1;
2782 for (int i = 0; i < n; ++i) {
2783 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
2784 totals += task_queue(i)->stats;
2785 }
2786 st->print_raw("tot "); totals.print(st); st->cr();
2787
2788 DEBUG_ONLY(totals.verify());
2789 }
2790
2791 void G1CollectedHeap::reset_taskqueue_stats() {
2792 const int n = workers() != NULL ? workers()->total_workers() : 1;
2793 for (int i = 0; i < n; ++i) {
2794 task_queue(i)->stats.reset();
2795 }
2796 }
2797 #endif // TASKQUEUE_STATS
2798
2799 void
2800 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2801 if (GC_locker::check_active_before_gc()) {
2802 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2803 }
2804
2805 if (PrintHeapAtGC) {
2806 Universe::print_heap_before_gc();
2807 }
2808
2809 {
2810 ResourceMark rm;
2811
2812 // This call will decide whether this pause is an initial-mark
2813 // pause. If it is, during_initial_mark_pause() will return true
2814 // for the duration of this pause.
2815 g1_policy()->decide_on_conc_mark_initiation();
2816
2817 char verbose_str[128];
2818 sprintf(verbose_str, "GC pause ");
2819 if (g1_policy()->in_young_gc_mode()) {
2820 if (g1_policy()->full_young_gcs())
2821 strcat(verbose_str, "(young)");
2822 else
2823 strcat(verbose_str, "(partial)");
2824 }
2825 if (g1_policy()->during_initial_mark_pause()) {
2826 strcat(verbose_str, " (initial-mark)");
2827 // We are about to start a marking cycle, so we increment the
2828 // full collection counter.
2829 increment_total_full_collections();
2830 }
2831
2832 // if PrintGCDetails is on, we'll print long statistics information
2833 // in the collector policy code, so let's not print this as the output
2834 // is messy if we do.
2835 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2836 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2837 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2838
2839 TraceMemoryManagerStats tms(false /* fullGC */);
2840
2841 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2842 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2843 guarantee(!is_gc_active(), "collection is not reentrant");
2844 assert(regions_accounted_for(), "Region leakage!");
2845
2846 increment_gc_time_stamp();
2847
2848 if (g1_policy()->in_young_gc_mode()) {
2849 assert(check_young_list_well_formed(),
2850 "young list should be well formed");
2851 }
2852
2853 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2854 IsGCActiveMark x;
2855
2856 gc_prologue(false);
2857 increment_total_collections(false /* full gc */);
2858
2859 #if G1_REM_SET_LOGGING
2860 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2861 print();
2862 #endif
2863
2864 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2865 HandleMark hm; // Discard invalid handles created during verification
2866 prepare_for_verify();
2867 gclog_or_tty->print(" VerifyBeforeGC:");
2868 Universe::verify(false);
2869 }
2870
2871 COMPILER2_PRESENT(DerivedPointerTable::clear());
2872
2873 // We want to turn off ref discovery, if necessary, and turn it back on
2874 // on again later if we do. XXX Dubious: why is discovery disabled?
2875 bool was_enabled = ref_processor()->discovery_enabled();
2876 if (was_enabled) ref_processor()->disable_discovery();
2877
2878 // Forget the current alloc region (we might even choose it to be part
2879 // of the collection set!).
2880 abandon_cur_alloc_region();
2881
2882 // The elapsed time induced by the start time below deliberately elides
2883 // the possible verification above.
2884 double start_time_sec = os::elapsedTime();
2885 size_t start_used_bytes = used();
2886
2887 #if YOUNG_LIST_VERBOSE
2888 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
2889 _young_list->print();
2890 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
2891 #endif // YOUNG_LIST_VERBOSE
2892
2893 g1_policy()->record_collection_pause_start(start_time_sec,
2894 start_used_bytes);
2895
2896 #if YOUNG_LIST_VERBOSE
2897 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
2898 _young_list->print();
2899 #endif // YOUNG_LIST_VERBOSE
2900
2901 if (g1_policy()->during_initial_mark_pause()) {
2902 concurrent_mark()->checkpointRootsInitialPre();
2903 }
2904 save_marks();
2905
2906 // We must do this before any possible evacuation that should propagate
2907 // marks.
2908 if (mark_in_progress()) {
2909 double start_time_sec = os::elapsedTime();
2910
2911 _cm->drainAllSATBBuffers();
2912 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2913 g1_policy()->record_satb_drain_time(finish_mark_ms);
2914 }
2915 // Record the number of elements currently on the mark stack, so we
2916 // only iterate over these. (Since evacuation may add to the mark
2917 // stack, doing more exposes race conditions.) If no mark is in
2918 // progress, this will be zero.
2919 _cm->set_oops_do_bound();
2920
2921 assert(regions_accounted_for(), "Region leakage.");
2922
2923 if (mark_in_progress())
2924 concurrent_mark()->newCSet();
2925
2926 #if YOUNG_LIST_VERBOSE
2927 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
2928 _young_list->print();
2929 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
2930 #endif // YOUNG_LIST_VERBOSE
2931
2932 g1_policy()->choose_collection_set(target_pause_time_ms);
2933
2934 // Nothing to do if we were unable to choose a collection set.
2935 #if G1_REM_SET_LOGGING
2936 gclog_or_tty->print_cr("\nAfter pause, heap:");
2937 print();
2938 #endif
2939 PrepareForRSScanningClosure prepare_for_rs_scan;
2940 collection_set_iterate(&prepare_for_rs_scan);
2941
2942 setup_surviving_young_words();
2943
2944 // Set up the gc allocation regions.
2945 get_gc_alloc_regions();
2946
2947 // Actually do the work...
2948 evacuate_collection_set();
2949
2950 free_collection_set(g1_policy()->collection_set());
2951 g1_policy()->clear_collection_set();
2952
2953 cleanup_surviving_young_words();
2954
2955 // Start a new incremental collection set for the next pause.
2956 g1_policy()->start_incremental_cset_building();
2957
2958 // Clear the _cset_fast_test bitmap in anticipation of adding
2959 // regions to the incremental collection set for the next
2960 // evacuation pause.
2961 clear_cset_fast_test();
2962
2963 if (g1_policy()->in_young_gc_mode()) {
2964 _young_list->reset_sampled_info();
2965
2966 // Don't check the whole heap at this point as the
2967 // GC alloc regions from this pause have been tagged
2968 // as survivors and moved on to the survivor list.
2969 // Survivor regions will fail the !is_young() check.
2970 assert(check_young_list_empty(false /* check_heap */),
2971 "young list should be empty");
2972
2973 #if YOUNG_LIST_VERBOSE
2974 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
2975 _young_list->print();
2976 #endif // YOUNG_LIST_VERBOSE
2977
2978 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2979 _young_list->first_survivor_region(),
2980 _young_list->last_survivor_region());
2981
2982 _young_list->reset_auxilary_lists();
2983 }
2984
2985 if (evacuation_failed()) {
2986 _summary_bytes_used = recalculate_used();
2987 } else {
2988 // The "used" of the the collection set have already been subtracted
2989 // when they were freed. Add in the bytes evacuated.
2990 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2991 }
2992
2993 if (g1_policy()->in_young_gc_mode() &&
2994 g1_policy()->during_initial_mark_pause()) {
2995 concurrent_mark()->checkpointRootsInitialPost();
2996 set_marking_started();
2997 // CAUTION: after the doConcurrentMark() call below,
2998 // the concurrent marking thread(s) could be running
2999 // concurrently with us. Make sure that anything after
3000 // this point does not assume that we are the only GC thread
3001 // running. Note: of course, the actual marking work will
3002 // not start until the safepoint itself is released in
3003 // ConcurrentGCThread::safepoint_desynchronize().
3004 doConcurrentMark();
3005 }
3006
3007 #if YOUNG_LIST_VERBOSE
3008 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3009 _young_list->print();
3010 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3011 #endif // YOUNG_LIST_VERBOSE
3012
3013 double end_time_sec = os::elapsedTime();
3014 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3015 g1_policy()->record_pause_time_ms(pause_time_ms);
3016 g1_policy()->record_collection_pause_end();
3017
3018 assert(regions_accounted_for(), "Region leakage.");
3019
3020 MemoryService::track_memory_usage();
3021
3022 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3023 HandleMark hm; // Discard invalid handles created during verification
3024 gclog_or_tty->print(" VerifyAfterGC:");
3025 prepare_for_verify();
3026 Universe::verify(false);
3027 }
3028
3029 if (was_enabled) ref_processor()->enable_discovery();
3030
3031 {
3032 size_t expand_bytes = g1_policy()->expansion_amount();
3033 if (expand_bytes > 0) {
3034 size_t bytes_before = capacity();
3035 expand(expand_bytes);
3036 }
3037 }
3038
3039 if (mark_in_progress()) {
3040 concurrent_mark()->update_g1_committed();
3041 }
3042
3043 #ifdef TRACESPINNING
3044 ParallelTaskTerminator::print_termination_counts();
3045 #endif
3046
3047 gc_epilogue(false);
3048 }
3049
3050 assert(verify_region_lists(), "Bad region lists.");
3051
3052 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3053 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3054 print_tracing_info();
3055 vm_exit(-1);
3056 }
3057 }
3058
3059 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3060 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3061
3062 if (PrintHeapAtGC) {
3063 Universe::print_heap_after_gc();
3064 }
3065 if (G1SummarizeRSetStats &&
3066 (G1SummarizeRSetStatsPeriod > 0) &&
3067 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3068 g1_rem_set()->print_summary_info();
3069 }
3070 }
3071
3072 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3073 {
3074 size_t gclab_word_size;
3075 switch (purpose) {
3076 case GCAllocForSurvived:
3077 gclab_word_size = YoungPLABSize;
3078 break;
3079 case GCAllocForTenured:
3080 gclab_word_size = OldPLABSize;
3081 break;
3082 default:
3083 assert(false, "unknown GCAllocPurpose");
3084 gclab_word_size = OldPLABSize;
3085 break;
3086 }
3087 return gclab_word_size;
3088 }
3089
3090
3091 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3092 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3093 // make sure we don't call set_gc_alloc_region() multiple times on
3094 // the same region
3095 assert(r == NULL || !r->is_gc_alloc_region(),
3096 "shouldn't already be a GC alloc region");
3097 assert(r == NULL || !r->isHumongous(),
3098 "humongous regions shouldn't be used as GC alloc regions");
3099
3100 HeapWord* original_top = NULL;
3101 if (r != NULL)
3102 original_top = r->top();
3103
3104 // We will want to record the used space in r as being there before gc.
3105 // One we install it as a GC alloc region it's eligible for allocation.
3106 // So record it now and use it later.
3107 size_t r_used = 0;
3108 if (r != NULL) {
3109 r_used = r->used();
3110
3111 if (G1CollectedHeap::use_parallel_gc_threads()) {
3112 // need to take the lock to guard against two threads calling
3113 // get_gc_alloc_region concurrently (very unlikely but...)
3114 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3115 r->save_marks();
3116 }
3117 }
3118 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3119 _gc_alloc_regions[purpose] = r;
3120 if (old_alloc_region != NULL) {
3121 // Replace aliases too.
3122 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3123 if (_gc_alloc_regions[ap] == old_alloc_region) {
3124 _gc_alloc_regions[ap] = r;
3125 }
3126 }
3127 }
3128 if (r != NULL) {
3129 push_gc_alloc_region(r);
3130 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3131 // We are using a region as a GC alloc region after it has been used
3132 // as a mutator allocation region during the current marking cycle.
3133 // The mutator-allocated objects are currently implicitly marked, but
3134 // when we move hr->next_top_at_mark_start() forward at the the end
3135 // of the GC pause, they won't be. We therefore mark all objects in
3136 // the "gap". We do this object-by-object, since marking densely
3137 // does not currently work right with marking bitmap iteration. This
3138 // means we rely on TLAB filling at the start of pauses, and no
3139 // "resuscitation" of filled TLAB's. If we want to do this, we need
3140 // to fix the marking bitmap iteration.
3141 HeapWord* curhw = r->next_top_at_mark_start();
3142 HeapWord* t = original_top;
3143
3144 while (curhw < t) {
3145 oop cur = (oop)curhw;
3146 // We'll assume parallel for generality. This is rare code.
3147 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3148 curhw = curhw + cur->size();
3149 }
3150 assert(curhw == t, "Should have parsed correctly.");
3151 }
3152 if (G1PolicyVerbose > 1) {
3153 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3154 "for survivors:", r->bottom(), original_top, r->end());
3155 r->print();
3156 }
3157 g1_policy()->record_before_bytes(r_used);
3158 }
3159 }
3160
3161 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3162 assert(Thread::current()->is_VM_thread() ||
3163 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
3164 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3165 "Precondition.");
3166 hr->set_is_gc_alloc_region(true);
3167 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3168 _gc_alloc_region_list = hr;
3169 }
3170
3171 #ifdef G1_DEBUG
3172 class FindGCAllocRegion: public HeapRegionClosure {
3173 public:
3174 bool doHeapRegion(HeapRegion* r) {
3175 if (r->is_gc_alloc_region()) {
3176 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3177 r->hrs_index(), r->bottom());
3178 }
3179 return false;
3180 }
3181 };
3182 #endif // G1_DEBUG
3183
3184 void G1CollectedHeap::forget_alloc_region_list() {
3185 assert(Thread::current()->is_VM_thread(), "Precondition");
3186 while (_gc_alloc_region_list != NULL) {
3187 HeapRegion* r = _gc_alloc_region_list;
3188 assert(r->is_gc_alloc_region(), "Invariant.");
3189 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3190 // newly allocated data in order to be able to apply deferred updates
3191 // before the GC is done for verification purposes (i.e to allow
3192 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3193 // collection.
3194 r->ContiguousSpace::set_saved_mark();
3195 _gc_alloc_region_list = r->next_gc_alloc_region();
3196 r->set_next_gc_alloc_region(NULL);
3197 r->set_is_gc_alloc_region(false);
3198 if (r->is_survivor()) {
3199 if (r->is_empty()) {
3200 r->set_not_young();
3201 } else {
3202 _young_list->add_survivor_region(r);
3203 }
3204 }
3205 if (r->is_empty()) {
3206 ++_free_regions;
3207 }
3208 }
3209 #ifdef G1_DEBUG
3210 FindGCAllocRegion fa;
3211 heap_region_iterate(&fa);
3212 #endif // G1_DEBUG
3213 }
3214
3215
3216 bool G1CollectedHeap::check_gc_alloc_regions() {
3217 // TODO: allocation regions check
3218 return true;
3219 }
3220
3221 void G1CollectedHeap::get_gc_alloc_regions() {
3222 // First, let's check that the GC alloc region list is empty (it should)
3223 assert(_gc_alloc_region_list == NULL, "invariant");
3224
3225 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3226 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3227 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3228
3229 // Create new GC alloc regions.
3230 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3231 _retained_gc_alloc_regions[ap] = NULL;
3232
3233 if (alloc_region != NULL) {
3234 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3235
3236 // let's make sure that the GC alloc region is not tagged as such
3237 // outside a GC operation
3238 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3239
3240 if (alloc_region->in_collection_set() ||
3241 alloc_region->top() == alloc_region->end() ||
3242 alloc_region->top() == alloc_region->bottom() ||
3243 alloc_region->isHumongous()) {
3244 // we will discard the current GC alloc region if
3245 // * it's in the collection set (it can happen!),
3246 // * it's already full (no point in using it),
3247 // * it's empty (this means that it was emptied during
3248 // a cleanup and it should be on the free list now), or
3249 // * it's humongous (this means that it was emptied
3250 // during a cleanup and was added to the free list, but
3251 // has been subseqently used to allocate a humongous
3252 // object that may be less than the region size).
3253
3254 alloc_region = NULL;
3255 }
3256 }
3257
3258 if (alloc_region == NULL) {
3259 // we will get a new GC alloc region
3260 alloc_region = newAllocRegionWithExpansion(ap, 0);
3261 } else {
3262 // the region was retained from the last collection
3263 ++_gc_alloc_region_counts[ap];
3264 if (G1PrintHeapRegions) {
3265 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
3266 "top "PTR_FORMAT,
3267 alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
3268 }
3269 }
3270
3271 if (alloc_region != NULL) {
3272 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3273 set_gc_alloc_region(ap, alloc_region);
3274 }
3275
3276 assert(_gc_alloc_regions[ap] == NULL ||
3277 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3278 "the GC alloc region should be tagged as such");
3279 assert(_gc_alloc_regions[ap] == NULL ||
3280 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3281 "the GC alloc region should be the same as the GC alloc list head");
3282 }
3283 // Set alternative regions for allocation purposes that have reached
3284 // their limit.
3285 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3286 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3287 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3288 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3289 }
3290 }
3291 assert(check_gc_alloc_regions(), "alloc regions messed up");
3292 }
3293
3294 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3295 // We keep a separate list of all regions that have been alloc regions in
3296 // the current collection pause. Forget that now. This method will
3297 // untag the GC alloc regions and tear down the GC alloc region
3298 // list. It's desirable that no regions are tagged as GC alloc
3299 // outside GCs.
3300 forget_alloc_region_list();
3301
3302 // The current alloc regions contain objs that have survived
3303 // collection. Make them no longer GC alloc regions.
3304 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3305 HeapRegion* r = _gc_alloc_regions[ap];
3306 _retained_gc_alloc_regions[ap] = NULL;
3307 _gc_alloc_region_counts[ap] = 0;
3308
3309 if (r != NULL) {
3310 // we retain nothing on _gc_alloc_regions between GCs
3311 set_gc_alloc_region(ap, NULL);
3312
3313 if (r->is_empty()) {
3314 // we didn't actually allocate anything in it; let's just put
3315 // it on the free list
3316 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3317 r->set_zero_fill_complete();
3318 put_free_region_on_list_locked(r);
3319 } else if (_retain_gc_alloc_region[ap] && !totally) {
3320 // retain it so that we can use it at the beginning of the next GC
3321 _retained_gc_alloc_regions[ap] = r;
3322 }
3323 }
3324 }
3325 }
3326
3327 #ifndef PRODUCT
3328 // Useful for debugging
3329
3330 void G1CollectedHeap::print_gc_alloc_regions() {
3331 gclog_or_tty->print_cr("GC alloc regions");
3332 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3333 HeapRegion* r = _gc_alloc_regions[ap];
3334 if (r == NULL) {
3335 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3336 } else {
3337 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3338 ap, r->bottom(), r->used());
3339 }
3340 }
3341 }
3342 #endif // PRODUCT
3343
3344 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3345 _drain_in_progress = false;
3346 set_evac_failure_closure(cl);
3347 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3348 }
3349
3350 void G1CollectedHeap::finalize_for_evac_failure() {
3351 assert(_evac_failure_scan_stack != NULL &&
3352 _evac_failure_scan_stack->length() == 0,
3353 "Postcondition");
3354 assert(!_drain_in_progress, "Postcondition");
3355 delete _evac_failure_scan_stack;
3356 _evac_failure_scan_stack = NULL;
3357 }
3358
3359
3360
3361 // *** Sequential G1 Evacuation
3362
3363 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3364 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3365 // let the caller handle alloc failure
3366 if (alloc_region == NULL) return NULL;
3367 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3368 "Either the object is humongous or the region isn't");
3369 HeapWord* block = alloc_region->allocate(word_size);
3370 if (block == NULL) {
3371 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3372 }
3373 return block;
3374 }
3375
3376 class G1IsAliveClosure: public BoolObjectClosure {
3377 G1CollectedHeap* _g1;
3378 public:
3379 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3380 void do_object(oop p) { assert(false, "Do not call."); }
3381 bool do_object_b(oop p) {
3382 // It is reachable if it is outside the collection set, or is inside
3383 // and forwarded.
3384
3385 #ifdef G1_DEBUG
3386 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3387 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3388 !_g1->obj_in_cs(p) || p->is_forwarded());
3389 #endif // G1_DEBUG
3390
3391 return !_g1->obj_in_cs(p) || p->is_forwarded();
3392 }
3393 };
3394
3395 class G1KeepAliveClosure: public OopClosure {
3396 G1CollectedHeap* _g1;
3397 public:
3398 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3399 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3400 void do_oop( oop* p) {
3401 oop obj = *p;
3402 #ifdef G1_DEBUG
3403 if (PrintGC && Verbose) {
3404 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3405 p, (void*) obj, (void*) *p);
3406 }
3407 #endif // G1_DEBUG
3408
3409 if (_g1->obj_in_cs(obj)) {
3410 assert( obj->is_forwarded(), "invariant" );
3411 *p = obj->forwardee();
3412 #ifdef G1_DEBUG
3413 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3414 (void*) obj, (void*) *p);
3415 #endif // G1_DEBUG
3416 }
3417 }
3418 };
3419
3420 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3421 private:
3422 G1CollectedHeap* _g1;
3423 DirtyCardQueue *_dcq;
3424 CardTableModRefBS* _ct_bs;
3425
3426 public:
3427 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3428 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3429
3430 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3431 virtual void do_oop( oop* p) { do_oop_work(p); }
3432 template <class T> void do_oop_work(T* p) {
3433 assert(_from->is_in_reserved(p), "paranoia");
3434 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3435 !_from->is_survivor()) {
3436 size_t card_index = _ct_bs->index_for(p);
3437 if (_ct_bs->mark_card_deferred(card_index)) {
3438 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3439 }
3440 }
3441 }
3442 };
3443
3444 class RemoveSelfPointerClosure: public ObjectClosure {
3445 private:
3446 G1CollectedHeap* _g1;
3447 ConcurrentMark* _cm;
3448 HeapRegion* _hr;
3449 size_t _prev_marked_bytes;
3450 size_t _next_marked_bytes;
3451 OopsInHeapRegionClosure *_cl;
3452 public:
3453 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3454 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3455 _next_marked_bytes(0), _cl(cl) {}
3456
3457 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3458 size_t next_marked_bytes() { return _next_marked_bytes; }
3459
3460 // The original idea here was to coalesce evacuated and dead objects.
3461 // However that caused complications with the block offset table (BOT).
3462 // In particular if there were two TLABs, one of them partially refined.
3463 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3464 // The BOT entries of the unrefined part of TLAB_2 point to the start
3465 // of TLAB_2. If the last object of the TLAB_1 and the first object
3466 // of TLAB_2 are coalesced, then the cards of the unrefined part
3467 // would point into middle of the filler object.
3468 //
3469 // The current approach is to not coalesce and leave the BOT contents intact.
3470 void do_object(oop obj) {
3471 if (obj->is_forwarded() && obj->forwardee() == obj) {
3472 // The object failed to move.
3473 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3474 _cm->markPrev(obj);
3475 assert(_cm->isPrevMarked(obj), "Should be marked!");
3476 _prev_marked_bytes += (obj->size() * HeapWordSize);
3477 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3478 _cm->markAndGrayObjectIfNecessary(obj);
3479 }
3480 obj->set_mark(markOopDesc::prototype());
3481 // While we were processing RSet buffers during the
3482 // collection, we actually didn't scan any cards on the
3483 // collection set, since we didn't want to update remebered
3484 // sets with entries that point into the collection set, given
3485 // that live objects fromthe collection set are about to move
3486 // and such entries will be stale very soon. This change also
3487 // dealt with a reliability issue which involved scanning a
3488 // card in the collection set and coming across an array that
3489 // was being chunked and looking malformed. The problem is
3490 // that, if evacuation fails, we might have remembered set
3491 // entries missing given that we skipped cards on the
3492 // collection set. So, we'll recreate such entries now.
3493 obj->oop_iterate(_cl);
3494 assert(_cm->isPrevMarked(obj), "Should be marked!");
3495 } else {
3496 // The object has been either evacuated or is dead. Fill it with a
3497 // dummy object.
3498 MemRegion mr((HeapWord*)obj, obj->size());
3499 CollectedHeap::fill_with_object(mr);
3500 _cm->clearRangeBothMaps(mr);
3501 }
3502 }
3503 };
3504
3505 void G1CollectedHeap::remove_self_forwarding_pointers() {
3506 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3507 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3508 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3509 OopsInHeapRegionClosure *cl;
3510 if (G1DeferredRSUpdate) {
3511 cl = &deferred_update;
3512 } else {
3513 cl = &immediate_update;
3514 }
3515 HeapRegion* cur = g1_policy()->collection_set();
3516 while (cur != NULL) {
3517 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3518
3519 RemoveSelfPointerClosure rspc(_g1h, cl);
3520 if (cur->evacuation_failed()) {
3521 assert(cur->in_collection_set(), "bad CS");
3522 cl->set_region(cur);
3523 cur->object_iterate(&rspc);
3524
3525 // A number of manipulations to make the TAMS be the current top,
3526 // and the marked bytes be the ones observed in the iteration.
3527 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3528 // The comments below are the postconditions achieved by the
3529 // calls. Note especially the last such condition, which says that
3530 // the count of marked bytes has been properly restored.
3531 cur->note_start_of_marking(false);
3532 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3533 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3534 // _next_marked_bytes == prev_marked_bytes.
3535 cur->note_end_of_marking();
3536 // _prev_top_at_mark_start == top(),
3537 // _prev_marked_bytes == prev_marked_bytes
3538 }
3539 // If there is no mark in progress, we modified the _next variables
3540 // above needlessly, but harmlessly.
3541 if (_g1h->mark_in_progress()) {
3542 cur->note_start_of_marking(false);
3543 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3544 // _next_marked_bytes == next_marked_bytes.
3545 }
3546
3547 // Now make sure the region has the right index in the sorted array.
3548 g1_policy()->note_change_in_marked_bytes(cur);
3549 }
3550 cur = cur->next_in_collection_set();
3551 }
3552 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3553
3554 // Now restore saved marks, if any.
3555 if (_objs_with_preserved_marks != NULL) {
3556 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3557 assert(_objs_with_preserved_marks->length() ==
3558 _preserved_marks_of_objs->length(), "Both or none.");
3559 guarantee(_objs_with_preserved_marks->length() ==
3560 _preserved_marks_of_objs->length(), "Both or none.");
3561 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3562 oop obj = _objs_with_preserved_marks->at(i);
3563 markOop m = _preserved_marks_of_objs->at(i);
3564 obj->set_mark(m);
3565 }
3566 // Delete the preserved marks growable arrays (allocated on the C heap).
3567 delete _objs_with_preserved_marks;
3568 delete _preserved_marks_of_objs;
3569 _objs_with_preserved_marks = NULL;
3570 _preserved_marks_of_objs = NULL;
3571 }
3572 }
3573
3574 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3575 _evac_failure_scan_stack->push(obj);
3576 }
3577
3578 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3579 assert(_evac_failure_scan_stack != NULL, "precondition");
3580
3581 while (_evac_failure_scan_stack->length() > 0) {
3582 oop obj = _evac_failure_scan_stack->pop();
3583 _evac_failure_closure->set_region(heap_region_containing(obj));
3584 obj->oop_iterate_backwards(_evac_failure_closure);
3585 }
3586 }
3587
3588 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3589 markOop m = old->mark();
3590 // forward to self
3591 assert(!old->is_forwarded(), "precondition");
3592
3593 old->forward_to(old);
3594 handle_evacuation_failure_common(old, m);
3595 }
3596
3597 oop
3598 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3599 oop old) {
3600 markOop m = old->mark();
3601 oop forward_ptr = old->forward_to_atomic(old);
3602 if (forward_ptr == NULL) {
3603 // Forward-to-self succeeded.
3604 if (_evac_failure_closure != cl) {
3605 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3606 assert(!_drain_in_progress,
3607 "Should only be true while someone holds the lock.");
3608 // Set the global evac-failure closure to the current thread's.
3609 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3610 set_evac_failure_closure(cl);
3611 // Now do the common part.
3612 handle_evacuation_failure_common(old, m);
3613 // Reset to NULL.
3614 set_evac_failure_closure(NULL);
3615 } else {
3616 // The lock is already held, and this is recursive.
3617 assert(_drain_in_progress, "This should only be the recursive case.");
3618 handle_evacuation_failure_common(old, m);
3619 }
3620 return old;
3621 } else {
3622 // Someone else had a place to copy it.
3623 return forward_ptr;
3624 }
3625 }
3626
3627 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3628 set_evacuation_failed(true);
3629
3630 preserve_mark_if_necessary(old, m);
3631
3632 HeapRegion* r = heap_region_containing(old);
3633 if (!r->evacuation_failed()) {
3634 r->set_evacuation_failed(true);
3635 if (G1PrintHeapRegions) {
3636 gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
3637 "["PTR_FORMAT","PTR_FORMAT")\n",
3638 r, r->bottom(), r->end());
3639 }
3640 }
3641
3642 push_on_evac_failure_scan_stack(old);
3643
3644 if (!_drain_in_progress) {
3645 // prevent recursion in copy_to_survivor_space()
3646 _drain_in_progress = true;
3647 drain_evac_failure_scan_stack();
3648 _drain_in_progress = false;
3649 }
3650 }
3651
3652 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3653 if (m != markOopDesc::prototype()) {
3654 if (_objs_with_preserved_marks == NULL) {
3655 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3656 _objs_with_preserved_marks =
3657 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3658 _preserved_marks_of_objs =
3659 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3660 }
3661 _objs_with_preserved_marks->push(obj);
3662 _preserved_marks_of_objs->push(m);
3663 }
3664 }
3665
3666 // *** Parallel G1 Evacuation
3667
3668 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3669 size_t word_size) {
3670 assert(!isHumongous(word_size),
3671 err_msg("we should not be seeing humongous allocation requests "
3672 "during GC, word_size = "SIZE_FORMAT, word_size));
3673
3674 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3675 // let the caller handle alloc failure
3676 if (alloc_region == NULL) return NULL;
3677
3678 HeapWord* block = alloc_region->par_allocate(word_size);
3679 if (block == NULL) {
3680 MutexLockerEx x(par_alloc_during_gc_lock(),
3681 Mutex::_no_safepoint_check_flag);
3682 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3683 }
3684 return block;
3685 }
3686
3687 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3688 bool par) {
3689 // Another thread might have obtained alloc_region for the given
3690 // purpose, and might be attempting to allocate in it, and might
3691 // succeed. Therefore, we can't do the "finalization" stuff on the
3692 // region below until we're sure the last allocation has happened.
3693 // We ensure this by allocating the remaining space with a garbage
3694 // object.
3695 if (par) par_allocate_remaining_space(alloc_region);
3696 // Now we can do the post-GC stuff on the region.
3697 alloc_region->note_end_of_copying();
3698 g1_policy()->record_after_bytes(alloc_region->used());
3699 }
3700
3701 HeapWord*
3702 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3703 HeapRegion* alloc_region,
3704 bool par,
3705 size_t word_size) {
3706 assert(!isHumongous(word_size),
3707 err_msg("we should not be seeing humongous allocation requests "
3708 "during GC, word_size = "SIZE_FORMAT, word_size));
3709
3710 HeapWord* block = NULL;
3711 // In the parallel case, a previous thread to obtain the lock may have
3712 // already assigned a new gc_alloc_region.
3713 if (alloc_region != _gc_alloc_regions[purpose]) {
3714 assert(par, "But should only happen in parallel case.");
3715 alloc_region = _gc_alloc_regions[purpose];
3716 if (alloc_region == NULL) return NULL;
3717 block = alloc_region->par_allocate(word_size);
3718 if (block != NULL) return block;
3719 // Otherwise, continue; this new region is empty, too.
3720 }
3721 assert(alloc_region != NULL, "We better have an allocation region");
3722 retire_alloc_region(alloc_region, par);
3723
3724 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3725 // Cannot allocate more regions for the given purpose.
3726 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3727 // Is there an alternative?
3728 if (purpose != alt_purpose) {
3729 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3730 // Has not the alternative region been aliased?
3731 if (alloc_region != alt_region && alt_region != NULL) {
3732 // Try to allocate in the alternative region.
3733 if (par) {
3734 block = alt_region->par_allocate(word_size);
3735 } else {
3736 block = alt_region->allocate(word_size);
3737 }
3738 // Make an alias.
3739 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3740 if (block != NULL) {
3741 return block;
3742 }
3743 retire_alloc_region(alt_region, par);
3744 }
3745 // Both the allocation region and the alternative one are full
3746 // and aliased, replace them with a new allocation region.
3747 purpose = alt_purpose;
3748 } else {
3749 set_gc_alloc_region(purpose, NULL);
3750 return NULL;
3751 }
3752 }
3753
3754 // Now allocate a new region for allocation.
3755 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3756
3757 // let the caller handle alloc failure
3758 if (alloc_region != NULL) {
3759
3760 assert(check_gc_alloc_regions(), "alloc regions messed up");
3761 assert(alloc_region->saved_mark_at_top(),
3762 "Mark should have been saved already.");
3763 // We used to assert that the region was zero-filled here, but no
3764 // longer.
3765
3766 // This must be done last: once it's installed, other regions may
3767 // allocate in it (without holding the lock.)
3768 set_gc_alloc_region(purpose, alloc_region);
3769
3770 if (par) {
3771 block = alloc_region->par_allocate(word_size);
3772 } else {
3773 block = alloc_region->allocate(word_size);
3774 }
3775 // Caller handles alloc failure.
3776 } else {
3777 // This sets other apis using the same old alloc region to NULL, also.
3778 set_gc_alloc_region(purpose, NULL);
3779 }
3780 return block; // May be NULL.
3781 }
3782
3783 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3784 HeapWord* block = NULL;
3785 size_t free_words;
3786 do {
3787 free_words = r->free()/HeapWordSize;
3788 // If there's too little space, no one can allocate, so we're done.
3789 if (free_words < CollectedHeap::min_fill_size()) return;
3790 // Otherwise, try to claim it.
3791 block = r->par_allocate(free_words);
3792 } while (block == NULL);
3793 fill_with_object(block, free_words);
3794 }
3795
3796 #ifndef PRODUCT
3797 bool GCLabBitMapClosure::do_bit(size_t offset) {
3798 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3799 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3800 return true;
3801 }
3802 #endif // PRODUCT
3803
3804 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3805 : _g1h(g1h),
3806 _refs(g1h->task_queue(queue_num)),
3807 _dcq(&g1h->dirty_card_queue_set()),
3808 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3809 _g1_rem(g1h->g1_rem_set()),
3810 _hash_seed(17), _queue_num(queue_num),
3811 _term_attempts(0),
3812 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
3813 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
3814 _age_table(false),
3815 _strong_roots_time(0), _term_time(0),
3816 _alloc_buffer_waste(0), _undo_waste(0)
3817 {
3818 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3819 // we "sacrifice" entry 0 to keep track of surviving bytes for
3820 // non-young regions (where the age is -1)
3821 // We also add a few elements at the beginning and at the end in
3822 // an attempt to eliminate cache contention
3823 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3824 size_t array_length = PADDING_ELEM_NUM +
3825 real_length +
3826 PADDING_ELEM_NUM;
3827 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3828 if (_surviving_young_words_base == NULL)
3829 vm_exit_out_of_memory(array_length * sizeof(size_t),
3830 "Not enough space for young surv histo.");
3831 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3832 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3833
3834 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
3835 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
3836
3837 _start = os::elapsedTime();
3838 }
3839
3840 void
3841 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
3842 {
3843 st->print_raw_cr("GC Termination Stats");
3844 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
3845 " ------waste (KiB)------");
3846 st->print_raw_cr("thr ms ms % ms % attempts"
3847 " total alloc undo");
3848 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
3849 " ------- ------- -------");
3850 }
3851
3852 void
3853 G1ParScanThreadState::print_termination_stats(int i,
3854 outputStream* const st) const
3855 {
3856 const double elapsed_ms = elapsed_time() * 1000.0;
3857 const double s_roots_ms = strong_roots_time() * 1000.0;
3858 const double term_ms = term_time() * 1000.0;
3859 st->print_cr("%3d %9.2f %9.2f %6.2f "
3860 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3861 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3862 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
3863 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
3864 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
3865 alloc_buffer_waste() * HeapWordSize / K,
3866 undo_waste() * HeapWordSize / K);
3867 }
3868
3869 #ifdef ASSERT
3870 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
3871 assert(ref != NULL, "invariant");
3872 assert(UseCompressedOops, "sanity");
3873 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
3874 oop p = oopDesc::load_decode_heap_oop(ref);
3875 assert(_g1h->is_in_g1_reserved(p),
3876 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
3877 return true;
3878 }
3879
3880 bool G1ParScanThreadState::verify_ref(oop* ref) const {
3881 assert(ref != NULL, "invariant");
3882 if (has_partial_array_mask(ref)) {
3883 // Must be in the collection set--it's already been copied.
3884 oop p = clear_partial_array_mask(ref);
3885 assert(_g1h->obj_in_cs(p),
3886 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
3887 } else {
3888 oop p = oopDesc::load_decode_heap_oop(ref);
3889 assert(_g1h->is_in_g1_reserved(p),
3890 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
3891 }
3892 return true;
3893 }
3894
3895 bool G1ParScanThreadState::verify_task(StarTask ref) const {
3896 if (ref.is_narrow()) {
3897 return verify_ref((narrowOop*) ref);
3898 } else {
3899 return verify_ref((oop*) ref);
3900 }
3901 }
3902 #endif // ASSERT
3903
3904 void G1ParScanThreadState::trim_queue() {
3905 StarTask ref;
3906 do {
3907 // Drain the overflow stack first, so other threads can steal.
3908 while (refs()->pop_overflow(ref)) {
3909 deal_with_reference(ref);
3910 }
3911 while (refs()->pop_local(ref)) {
3912 deal_with_reference(ref);
3913 }
3914 } while (!refs()->is_empty());
3915 }
3916
3917 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3918 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3919 _par_scan_state(par_scan_state) { }
3920
3921 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3922 // This is called _after_ do_oop_work has been called, hence after
3923 // the object has been relocated to its new location and *p points
3924 // to its new location.
3925
3926 T heap_oop = oopDesc::load_heap_oop(p);
3927 if (!oopDesc::is_null(heap_oop)) {
3928 oop obj = oopDesc::decode_heap_oop(heap_oop);
3929 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3930 "shouldn't still be in the CSet if evacuation didn't fail.");
3931 HeapWord* addr = (HeapWord*)obj;
3932 if (_g1->is_in_g1_reserved(addr))
3933 _cm->grayRoot(oop(addr));
3934 }
3935 }
3936
3937 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3938 size_t word_sz = old->size();
3939 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3940 // +1 to make the -1 indexes valid...
3941 int young_index = from_region->young_index_in_cset()+1;
3942 assert( (from_region->is_young() && young_index > 0) ||
3943 (!from_region->is_young() && young_index == 0), "invariant" );
3944 G1CollectorPolicy* g1p = _g1->g1_policy();
3945 markOop m = old->mark();
3946 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3947 : m->age();
3948 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3949 word_sz);
3950 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3951 oop obj = oop(obj_ptr);
3952
3953 if (obj_ptr == NULL) {
3954 // This will either forward-to-self, or detect that someone else has
3955 // installed a forwarding pointer.
3956 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3957 return _g1->handle_evacuation_failure_par(cl, old);
3958 }
3959
3960 // We're going to allocate linearly, so might as well prefetch ahead.
3961 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3962
3963 oop forward_ptr = old->forward_to_atomic(obj);
3964 if (forward_ptr == NULL) {
3965 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3966 if (g1p->track_object_age(alloc_purpose)) {
3967 // We could simply do obj->incr_age(). However, this causes a
3968 // performance issue. obj->incr_age() will first check whether
3969 // the object has a displaced mark by checking its mark word;
3970 // getting the mark word from the new location of the object
3971 // stalls. So, given that we already have the mark word and we
3972 // are about to install it anyway, it's better to increase the
3973 // age on the mark word, when the object does not have a
3974 // displaced mark word. We're not expecting many objects to have
3975 // a displaced marked word, so that case is not optimized
3976 // further (it could be...) and we simply call obj->incr_age().
3977
3978 if (m->has_displaced_mark_helper()) {
3979 // in this case, we have to install the mark word first,
3980 // otherwise obj looks to be forwarded (the old mark word,
3981 // which contains the forward pointer, was copied)
3982 obj->set_mark(m);
3983 obj->incr_age();
3984 } else {
3985 m = m->incr_age();
3986 obj->set_mark(m);
3987 }
3988 _par_scan_state->age_table()->add(obj, word_sz);
3989 } else {
3990 obj->set_mark(m);
3991 }
3992
3993 // preserve "next" mark bit
3994 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3995 if (!use_local_bitmaps ||
3996 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3997 // if we couldn't mark it on the local bitmap (this happens when
3998 // the object was not allocated in the GCLab), we have to bite
3999 // the bullet and do the standard parallel mark
4000 _cm->markAndGrayObjectIfNecessary(obj);
4001 }
4002 #if 1
4003 if (_g1->isMarkedNext(old)) {
4004 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4005 }
4006 #endif
4007 }
4008
4009 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4010 surv_young_words[young_index] += word_sz;
4011
4012 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4013 arrayOop(old)->set_length(0);
4014 oop* old_p = set_partial_array_mask(old);
4015 _par_scan_state->push_on_queue(old_p);
4016 } else {
4017 // No point in using the slower heap_region_containing() method,
4018 // given that we know obj is in the heap.
4019 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4020 obj->oop_iterate_backwards(_scanner);
4021 }
4022 } else {
4023 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4024 obj = forward_ptr;
4025 }
4026 return obj;
4027 }
4028
4029 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4030 template <class T>
4031 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4032 ::do_oop_work(T* p) {
4033 oop obj = oopDesc::load_decode_heap_oop(p);
4034 assert(barrier != G1BarrierRS || obj != NULL,
4035 "Precondition: G1BarrierRS implies obj is nonNull");
4036
4037 // here the null check is implicit in the cset_fast_test() test
4038 if (_g1->in_cset_fast_test(obj)) {
4039 #if G1_REM_SET_LOGGING
4040 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4041 "into CS.", p, (void*) obj);
4042 #endif
4043 if (obj->is_forwarded()) {
4044 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4045 } else {
4046 oop copy_oop = copy_to_survivor_space(obj);
4047 oopDesc::encode_store_heap_oop(p, copy_oop);
4048 }
4049 // When scanning the RS, we only care about objs in CS.
4050 if (barrier == G1BarrierRS) {
4051 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4052 }
4053 }
4054
4055 if (barrier == G1BarrierEvac && obj != NULL) {
4056 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4057 }
4058
4059 if (do_gen_barrier && obj != NULL) {
4060 par_do_barrier(p);
4061 }
4062 }
4063
4064 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4065 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4066
4067 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4068 assert(has_partial_array_mask(p), "invariant");
4069 oop old = clear_partial_array_mask(p);
4070 assert(old->is_objArray(), "must be obj array");
4071 assert(old->is_forwarded(), "must be forwarded");
4072 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4073
4074 objArrayOop obj = objArrayOop(old->forwardee());
4075 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4076 // Process ParGCArrayScanChunk elements now
4077 // and push the remainder back onto queue
4078 int start = arrayOop(old)->length();
4079 int end = obj->length();
4080 int remainder = end - start;
4081 assert(start <= end, "just checking");
4082 if (remainder > 2 * ParGCArrayScanChunk) {
4083 // Test above combines last partial chunk with a full chunk
4084 end = start + ParGCArrayScanChunk;
4085 arrayOop(old)->set_length(end);
4086 // Push remainder.
4087 oop* old_p = set_partial_array_mask(old);
4088 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4089 _par_scan_state->push_on_queue(old_p);
4090 } else {
4091 // Restore length so that the heap remains parsable in
4092 // case of evacuation failure.
4093 arrayOop(old)->set_length(end);
4094 }
4095 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4096 // process our set of indices (include header in first chunk)
4097 obj->oop_iterate_range(&_scanner, start, end);
4098 }
4099
4100 class G1ParEvacuateFollowersClosure : public VoidClosure {
4101 protected:
4102 G1CollectedHeap* _g1h;
4103 G1ParScanThreadState* _par_scan_state;
4104 RefToScanQueueSet* _queues;
4105 ParallelTaskTerminator* _terminator;
4106
4107 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4108 RefToScanQueueSet* queues() { return _queues; }
4109 ParallelTaskTerminator* terminator() { return _terminator; }
4110
4111 public:
4112 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4113 G1ParScanThreadState* par_scan_state,
4114 RefToScanQueueSet* queues,
4115 ParallelTaskTerminator* terminator)
4116 : _g1h(g1h), _par_scan_state(par_scan_state),
4117 _queues(queues), _terminator(terminator) {}
4118
4119 void do_void();
4120
4121 private:
4122 inline bool offer_termination();
4123 };
4124
4125 bool G1ParEvacuateFollowersClosure::offer_termination() {
4126 G1ParScanThreadState* const pss = par_scan_state();
4127 pss->start_term_time();
4128 const bool res = terminator()->offer_termination();
4129 pss->end_term_time();
4130 return res;
4131 }
4132
4133 void G1ParEvacuateFollowersClosure::do_void() {
4134 StarTask stolen_task;
4135 G1ParScanThreadState* const pss = par_scan_state();
4136 pss->trim_queue();
4137
4138 do {
4139 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4140 assert(pss->verify_task(stolen_task), "sanity");
4141 if (stolen_task.is_narrow()) {
4142 pss->push_on_queue((narrowOop*) stolen_task);
4143 } else {
4144 pss->push_on_queue((oop*) stolen_task);
4145 }
4146 pss->trim_queue();
4147 }
4148 } while (!offer_termination());
4149
4150 pss->retire_alloc_buffers();
4151 }
4152
4153 class G1ParTask : public AbstractGangTask {
4154 protected:
4155 G1CollectedHeap* _g1h;
4156 RefToScanQueueSet *_queues;
4157 ParallelTaskTerminator _terminator;
4158 int _n_workers;
4159
4160 Mutex _stats_lock;
4161 Mutex* stats_lock() { return &_stats_lock; }
4162
4163 size_t getNCards() {
4164 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4165 / G1BlockOffsetSharedArray::N_bytes;
4166 }
4167
4168 public:
4169 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4170 : AbstractGangTask("G1 collection"),
4171 _g1h(g1h),
4172 _queues(task_queues),
4173 _terminator(workers, _queues),
4174 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4175 _n_workers(workers)
4176 {}
4177
4178 RefToScanQueueSet* queues() { return _queues; }
4179
4180 RefToScanQueue *work_queue(int i) {
4181 return queues()->queue(i);
4182 }
4183
4184 void work(int i) {
4185 if (i >= _n_workers) return; // no work needed this round
4186
4187 double start_time_ms = os::elapsedTime() * 1000.0;
4188 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4189
4190 ResourceMark rm;
4191 HandleMark hm;
4192
4193 G1ParScanThreadState pss(_g1h, i);
4194 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4195 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4196 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4197
4198 pss.set_evac_closure(&scan_evac_cl);
4199 pss.set_evac_failure_closure(&evac_failure_cl);
4200 pss.set_partial_scan_closure(&partial_scan_cl);
4201
4202 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4203 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4204 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4205 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4206
4207 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4208 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4209 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4210
4211 OopsInHeapRegionClosure *scan_root_cl;
4212 OopsInHeapRegionClosure *scan_perm_cl;
4213
4214 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4215 scan_root_cl = &scan_mark_root_cl;
4216 scan_perm_cl = &scan_mark_perm_cl;
4217 } else {
4218 scan_root_cl = &only_scan_root_cl;
4219 scan_perm_cl = &only_scan_perm_cl;
4220 }
4221
4222 pss.start_strong_roots();
4223 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4224 SharedHeap::SO_AllClasses,
4225 scan_root_cl,
4226 &push_heap_rs_cl,
4227 scan_perm_cl,
4228 i);
4229 pss.end_strong_roots();
4230 {
4231 double start = os::elapsedTime();
4232 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4233 evac.do_void();
4234 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4235 double term_ms = pss.term_time()*1000.0;
4236 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4237 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4238 }
4239 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4240 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4241
4242 // Clean up any par-expanded rem sets.
4243 HeapRegionRemSet::par_cleanup();
4244
4245 if (ParallelGCVerbose) {
4246 MutexLocker x(stats_lock());
4247 pss.print_termination_stats(i);
4248 }
4249
4250 assert(pss.refs()->is_empty(), "should be empty");
4251 double end_time_ms = os::elapsedTime() * 1000.0;
4252 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4253 }
4254 };
4255
4256 // *** Common G1 Evacuation Stuff
4257
4258 // This method is run in a GC worker.
4259
4260 void
4261 G1CollectedHeap::
4262 g1_process_strong_roots(bool collecting_perm_gen,
4263 SharedHeap::ScanningOption so,
4264 OopClosure* scan_non_heap_roots,
4265 OopsInHeapRegionClosure* scan_rs,
4266 OopsInGenClosure* scan_perm,
4267 int worker_i) {
4268 // First scan the strong roots, including the perm gen.
4269 double ext_roots_start = os::elapsedTime();
4270 double closure_app_time_sec = 0.0;
4271
4272 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4273 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4274 buf_scan_perm.set_generation(perm_gen());
4275
4276 // Walk the code cache w/o buffering, because StarTask cannot handle
4277 // unaligned oop locations.
4278 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4279
4280 process_strong_roots(false, // no scoping; this is parallel code
4281 collecting_perm_gen, so,
4282 &buf_scan_non_heap_roots,
4283 &eager_scan_code_roots,
4284 &buf_scan_perm);
4285
4286 // Finish up any enqueued closure apps.
4287 buf_scan_non_heap_roots.done();
4288 buf_scan_perm.done();
4289 double ext_roots_end = os::elapsedTime();
4290 g1_policy()->reset_obj_copy_time(worker_i);
4291 double obj_copy_time_sec =
4292 buf_scan_non_heap_roots.closure_app_seconds() +
4293 buf_scan_perm.closure_app_seconds();
4294 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4295 double ext_root_time_ms =
4296 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4297 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4298
4299 // Scan strong roots in mark stack.
4300 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4301 concurrent_mark()->oops_do(scan_non_heap_roots);
4302 }
4303 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4304 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4305
4306 // XXX What should this be doing in the parallel case?
4307 g1_policy()->record_collection_pause_end_CH_strong_roots();
4308 // Now scan the complement of the collection set.
4309 if (scan_rs != NULL) {
4310 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4311 }
4312 // Finish with the ref_processor roots.
4313 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4314 ref_processor()->oops_do(scan_non_heap_roots);
4315 }
4316 g1_policy()->record_collection_pause_end_G1_strong_roots();
4317 _process_strong_tasks->all_tasks_completed();
4318 }
4319
4320 void
4321 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4322 OopClosure* non_root_closure) {
4323 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4324 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4325 }
4326
4327
4328 class SaveMarksClosure: public HeapRegionClosure {
4329 public:
4330 bool doHeapRegion(HeapRegion* r) {
4331 r->save_marks();
4332 return false;
4333 }
4334 };
4335
4336 void G1CollectedHeap::save_marks() {
4337 if (!CollectedHeap::use_parallel_gc_threads()) {
4338 SaveMarksClosure sm;
4339 heap_region_iterate(&sm);
4340 }
4341 // We do this even in the parallel case
4342 perm_gen()->save_marks();
4343 }
4344
4345 void G1CollectedHeap::evacuate_collection_set() {
4346 set_evacuation_failed(false);
4347
4348 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4349 concurrent_g1_refine()->set_use_cache(false);
4350 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4351
4352 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4353 set_par_threads(n_workers);
4354 G1ParTask g1_par_task(this, n_workers, _task_queues);
4355
4356 init_for_evac_failure(NULL);
4357
4358 rem_set()->prepare_for_younger_refs_iterate(true);
4359
4360 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4361 double start_par = os::elapsedTime();
4362 if (G1CollectedHeap::use_parallel_gc_threads()) {
4363 // The individual threads will set their evac-failure closures.
4364 StrongRootsScope srs(this);
4365 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4366 workers()->run_task(&g1_par_task);
4367 } else {
4368 StrongRootsScope srs(this);
4369 g1_par_task.work(0);
4370 }
4371
4372 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4373 g1_policy()->record_par_time(par_time);
4374 set_par_threads(0);
4375 // Is this the right thing to do here? We don't save marks
4376 // on individual heap regions when we allocate from
4377 // them in parallel, so this seems like the correct place for this.
4378 retire_all_alloc_regions();
4379 {
4380 G1IsAliveClosure is_alive(this);
4381 G1KeepAliveClosure keep_alive(this);
4382 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4383 }
4384 release_gc_alloc_regions(false /* totally */);
4385 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4386
4387 concurrent_g1_refine()->clear_hot_cache();
4388 concurrent_g1_refine()->set_use_cache(true);
4389
4390 finalize_for_evac_failure();
4391
4392 // Must do this before removing self-forwarding pointers, which clears
4393 // the per-region evac-failure flags.
4394 concurrent_mark()->complete_marking_in_collection_set();
4395
4396 if (evacuation_failed()) {
4397 remove_self_forwarding_pointers();
4398 if (PrintGCDetails) {
4399 gclog_or_tty->print(" (to-space overflow)");
4400 } else if (PrintGC) {
4401 gclog_or_tty->print("--");
4402 }
4403 }
4404
4405 if (G1DeferredRSUpdate) {
4406 RedirtyLoggedCardTableEntryFastClosure redirty;
4407 dirty_card_queue_set().set_closure(&redirty);
4408 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4409
4410 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4411 dcq.merge_bufferlists(&dirty_card_queue_set());
4412 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4413 }
4414 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4415 }
4416
4417 void G1CollectedHeap::free_region(HeapRegion* hr) {
4418 size_t pre_used = 0;
4419 size_t cleared_h_regions = 0;
4420 size_t freed_regions = 0;
4421 UncleanRegionList local_list;
4422
4423 HeapWord* start = hr->bottom();
4424 HeapWord* end = hr->prev_top_at_mark_start();
4425 size_t used_bytes = hr->used();
4426 size_t live_bytes = hr->max_live_bytes();
4427 if (used_bytes > 0) {
4428 guarantee( live_bytes <= used_bytes, "invariant" );
4429 } else {
4430 guarantee( live_bytes == 0, "invariant" );
4431 }
4432
4433 size_t garbage_bytes = used_bytes - live_bytes;
4434 if (garbage_bytes > 0)
4435 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4436
4437 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4438 &local_list);
4439 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4440 &local_list);
4441 }
4442
4443 void
4444 G1CollectedHeap::free_region_work(HeapRegion* hr,
4445 size_t& pre_used,
4446 size_t& cleared_h_regions,
4447 size_t& freed_regions,
4448 UncleanRegionList* list,
4449 bool par) {
4450 pre_used += hr->used();
4451 if (hr->isHumongous()) {
4452 assert(hr->startsHumongous(),
4453 "Only the start of a humongous region should be freed.");
4454 int ind = _hrs->find(hr);
4455 assert(ind != -1, "Should have an index.");
4456 // Clear the start region.
4457 hr->hr_clear(par, true /*clear_space*/);
4458 list->insert_before_head(hr);
4459 cleared_h_regions++;
4460 freed_regions++;
4461 // Clear any continued regions.
4462 ind++;
4463 while ((size_t)ind < n_regions()) {
4464 HeapRegion* hrc = _hrs->at(ind);
4465 if (!hrc->continuesHumongous()) break;
4466 // Otherwise, does continue the H region.
4467 assert(hrc->humongous_start_region() == hr, "Huh?");
4468 hrc->hr_clear(par, true /*clear_space*/);
4469 cleared_h_regions++;
4470 freed_regions++;
4471 list->insert_before_head(hrc);
4472 ind++;
4473 }
4474 } else {
4475 hr->hr_clear(par, true /*clear_space*/);
4476 list->insert_before_head(hr);
4477 freed_regions++;
4478 // If we're using clear2, this should not be enabled.
4479 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4480 }
4481 }
4482
4483 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4484 size_t cleared_h_regions,
4485 size_t freed_regions,
4486 UncleanRegionList* list) {
4487 if (list != NULL && list->sz() > 0) {
4488 prepend_region_list_on_unclean_list(list);
4489 }
4490 // Acquire a lock, if we're parallel, to update possibly-shared
4491 // variables.
4492 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4493 {
4494 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4495 _summary_bytes_used -= pre_used;
4496 _num_humongous_regions -= (int) cleared_h_regions;
4497 _free_regions += freed_regions;
4498 }
4499 }
4500
4501
4502 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4503 while (list != NULL) {
4504 guarantee( list->is_young(), "invariant" );
4505
4506 HeapWord* bottom = list->bottom();
4507 HeapWord* end = list->end();
4508 MemRegion mr(bottom, end);
4509 ct_bs->dirty(mr);
4510
4511 list = list->get_next_young_region();
4512 }
4513 }
4514
4515
4516 class G1ParCleanupCTTask : public AbstractGangTask {
4517 CardTableModRefBS* _ct_bs;
4518 G1CollectedHeap* _g1h;
4519 HeapRegion* volatile _su_head;
4520 public:
4521 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4522 G1CollectedHeap* g1h,
4523 HeapRegion* survivor_list) :
4524 AbstractGangTask("G1 Par Cleanup CT Task"),
4525 _ct_bs(ct_bs),
4526 _g1h(g1h),
4527 _su_head(survivor_list)
4528 { }
4529
4530 void work(int i) {
4531 HeapRegion* r;
4532 while (r = _g1h->pop_dirty_cards_region()) {
4533 clear_cards(r);
4534 }
4535 // Redirty the cards of the survivor regions.
4536 dirty_list(&this->_su_head);
4537 }
4538
4539 void clear_cards(HeapRegion* r) {
4540 // Cards for Survivor regions will be dirtied later.
4541 if (!r->is_survivor()) {
4542 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4543 }
4544 }
4545
4546 void dirty_list(HeapRegion* volatile * head_ptr) {
4547 HeapRegion* head;
4548 do {
4549 // Pop region off the list.
4550 head = *head_ptr;
4551 if (head != NULL) {
4552 HeapRegion* r = (HeapRegion*)
4553 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4554 if (r == head) {
4555 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4556 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4557 }
4558 }
4559 } while (*head_ptr != NULL);
4560 }
4561 };
4562
4563
4564 #ifndef PRODUCT
4565 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4566 CardTableModRefBS* _ct_bs;
4567 public:
4568 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4569 : _ct_bs(ct_bs)
4570 { }
4571 virtual bool doHeapRegion(HeapRegion* r)
4572 {
4573 MemRegion mr(r->bottom(), r->end());
4574 if (r->is_survivor()) {
4575 _ct_bs->verify_dirty_region(mr);
4576 } else {
4577 _ct_bs->verify_clean_region(mr);
4578 }
4579 return false;
4580 }
4581 };
4582 #endif
4583
4584 void G1CollectedHeap::cleanUpCardTable() {
4585 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4586 double start = os::elapsedTime();
4587
4588 // Iterate over the dirty cards region list.
4589 G1ParCleanupCTTask cleanup_task(ct_bs, this,
4590 _young_list->first_survivor_region());
4591
4592 if (ParallelGCThreads > 0) {
4593 set_par_threads(workers()->total_workers());
4594 workers()->run_task(&cleanup_task);
4595 set_par_threads(0);
4596 } else {
4597 while (_dirty_cards_region_list) {
4598 HeapRegion* r = _dirty_cards_region_list;
4599 cleanup_task.clear_cards(r);
4600 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4601 if (_dirty_cards_region_list == r) {
4602 // The last region.
4603 _dirty_cards_region_list = NULL;
4604 }
4605 r->set_next_dirty_cards_region(NULL);
4606 }
4607 // now, redirty the cards of the survivor regions
4608 // (it seemed faster to do it this way, instead of iterating over
4609 // all regions and then clearing / dirtying as appropriate)
4610 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4611 }
4612
4613 double elapsed = os::elapsedTime() - start;
4614 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4615 #ifndef PRODUCT
4616 if (G1VerifyCTCleanup || VerifyAfterGC) {
4617 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
4618 heap_region_iterate(&cleanup_verifier);
4619 }
4620 #endif
4621 }
4622
4623 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4624 if (g1_policy()->should_do_collection_pause(word_size)) {
4625 do_collection_pause();
4626 }
4627 }
4628
4629 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4630 double young_time_ms = 0.0;
4631 double non_young_time_ms = 0.0;
4632
4633 // Since the collection set is a superset of the the young list,
4634 // all we need to do to clear the young list is clear its
4635 // head and length, and unlink any young regions in the code below
4636 _young_list->clear();
4637
4638 G1CollectorPolicy* policy = g1_policy();
4639
4640 double start_sec = os::elapsedTime();
4641 bool non_young = true;
4642
4643 HeapRegion* cur = cs_head;
4644 int age_bound = -1;
4645 size_t rs_lengths = 0;
4646
4647 while (cur != NULL) {
4648 if (non_young) {
4649 if (cur->is_young()) {
4650 double end_sec = os::elapsedTime();
4651 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4652 non_young_time_ms += elapsed_ms;
4653
4654 start_sec = os::elapsedTime();
4655 non_young = false;
4656 }
4657 } else {
4658 if (!cur->is_on_free_list()) {
4659 double end_sec = os::elapsedTime();
4660 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4661 young_time_ms += elapsed_ms;
4662
4663 start_sec = os::elapsedTime();
4664 non_young = true;
4665 }
4666 }
4667
4668 rs_lengths += cur->rem_set()->occupied();
4669
4670 HeapRegion* next = cur->next_in_collection_set();
4671 assert(cur->in_collection_set(), "bad CS");
4672 cur->set_next_in_collection_set(NULL);
4673 cur->set_in_collection_set(false);
4674
4675 if (cur->is_young()) {
4676 int index = cur->young_index_in_cset();
4677 guarantee( index != -1, "invariant" );
4678 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4679 size_t words_survived = _surviving_young_words[index];
4680 cur->record_surv_words_in_group(words_survived);
4681
4682 // At this point the we have 'popped' cur from the collection set
4683 // (linked via next_in_collection_set()) but it is still in the
4684 // young list (linked via next_young_region()). Clear the
4685 // _next_young_region field.
4686 cur->set_next_young_region(NULL);
4687 } else {
4688 int index = cur->young_index_in_cset();
4689 guarantee( index == -1, "invariant" );
4690 }
4691
4692 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4693 (!cur->is_young() && cur->young_index_in_cset() == -1),
4694 "invariant" );
4695
4696 if (!cur->evacuation_failed()) {
4697 // And the region is empty.
4698 assert(!cur->is_empty(),
4699 "Should not have empty regions in a CS.");
4700 free_region(cur);
4701 } else {
4702 cur->uninstall_surv_rate_group();
4703 if (cur->is_young())
4704 cur->set_young_index_in_cset(-1);
4705 cur->set_not_young();
4706 cur->set_evacuation_failed(false);
4707 }
4708 cur = next;
4709 }
4710
4711 policy->record_max_rs_lengths(rs_lengths);
4712 policy->cset_regions_freed();
4713
4714 double end_sec = os::elapsedTime();
4715 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4716 if (non_young)
4717 non_young_time_ms += elapsed_ms;
4718 else
4719 young_time_ms += elapsed_ms;
4720
4721 policy->record_young_free_cset_time_ms(young_time_ms);
4722 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4723 }
4724
4725 // This routine is similar to the above but does not record
4726 // any policy statistics or update free lists; we are abandoning
4727 // the current incremental collection set in preparation of a
4728 // full collection. After the full GC we will start to build up
4729 // the incremental collection set again.
4730 // This is only called when we're doing a full collection
4731 // and is immediately followed by the tearing down of the young list.
4732
4733 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
4734 HeapRegion* cur = cs_head;
4735
4736 while (cur != NULL) {
4737 HeapRegion* next = cur->next_in_collection_set();
4738 assert(cur->in_collection_set(), "bad CS");
4739 cur->set_next_in_collection_set(NULL);
4740 cur->set_in_collection_set(false);
4741 cur->set_young_index_in_cset(-1);
4742 cur = next;
4743 }
4744 }
4745
4746 HeapRegion*
4747 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4748 assert(ZF_mon->owned_by_self(), "Precondition");
4749 HeapRegion* res = pop_unclean_region_list_locked();
4750 if (res != NULL) {
4751 assert(!res->continuesHumongous() &&
4752 res->zero_fill_state() != HeapRegion::Allocated,
4753 "Only free regions on unclean list.");
4754 if (zero_filled) {
4755 res->ensure_zero_filled_locked();
4756 res->set_zero_fill_allocated();
4757 }
4758 }
4759 return res;
4760 }
4761
4762 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4763 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4764 return alloc_region_from_unclean_list_locked(zero_filled);
4765 }
4766
4767 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4768 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4769 put_region_on_unclean_list_locked(r);
4770 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4771 }
4772
4773 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4774 MutexLockerEx x(Cleanup_mon);
4775 set_unclean_regions_coming_locked(b);
4776 }
4777
4778 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4779 assert(Cleanup_mon->owned_by_self(), "Precondition");
4780 _unclean_regions_coming = b;
4781 // Wake up mutator threads that might be waiting for completeCleanup to
4782 // finish.
4783 if (!b) Cleanup_mon->notify_all();
4784 }
4785
4786 void G1CollectedHeap::wait_for_cleanup_complete() {
4787 MutexLockerEx x(Cleanup_mon);
4788 wait_for_cleanup_complete_locked();
4789 }
4790
4791 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4792 assert(Cleanup_mon->owned_by_self(), "precondition");
4793 while (_unclean_regions_coming) {
4794 Cleanup_mon->wait();
4795 }
4796 }
4797
4798 void
4799 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4800 assert(ZF_mon->owned_by_self(), "precondition.");
4801 #ifdef ASSERT
4802 if (r->is_gc_alloc_region()) {
4803 ResourceMark rm;
4804 stringStream region_str;
4805 print_on(®ion_str);
4806 assert(!r->is_gc_alloc_region(), err_msg("Unexpected GC allocation region: %s",
4807 region_str.as_string()));
4808 }
4809 #endif
4810 _unclean_region_list.insert_before_head(r);
4811 }
4812
4813 void
4814 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4815 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4816 prepend_region_list_on_unclean_list_locked(list);
4817 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4818 }
4819
4820 void
4821 G1CollectedHeap::
4822 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4823 assert(ZF_mon->owned_by_self(), "precondition.");
4824 _unclean_region_list.prepend_list(list);
4825 }
4826
4827 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4828 assert(ZF_mon->owned_by_self(), "precondition.");
4829 HeapRegion* res = _unclean_region_list.pop();
4830 if (res != NULL) {
4831 // Inform ZF thread that there's a new unclean head.
4832 if (_unclean_region_list.hd() != NULL && should_zf())
4833 ZF_mon->notify_all();
4834 }
4835 return res;
4836 }
4837
4838 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4839 assert(ZF_mon->owned_by_self(), "precondition.");
4840 return _unclean_region_list.hd();
4841 }
4842
4843
4844 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4845 assert(ZF_mon->owned_by_self(), "Precondition");
4846 HeapRegion* r = peek_unclean_region_list_locked();
4847 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4848 // Result of below must be equal to "r", since we hold the lock.
4849 (void)pop_unclean_region_list_locked();
4850 put_free_region_on_list_locked(r);
4851 return true;
4852 } else {
4853 return false;
4854 }
4855 }
4856
4857 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4858 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4859 return move_cleaned_region_to_free_list_locked();
4860 }
4861
4862
4863 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4864 assert(ZF_mon->owned_by_self(), "precondition.");
4865 assert(_free_region_list_size == free_region_list_length(), "Inv");
4866 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4867 "Regions on free list must be zero filled");
4868 assert(!r->isHumongous(), "Must not be humongous.");
4869 assert(r->is_empty(), "Better be empty");
4870 assert(!r->is_on_free_list(),
4871 "Better not already be on free list");
4872 assert(!r->is_on_unclean_list(),
4873 "Better not already be on unclean list");
4874 r->set_on_free_list(true);
4875 r->set_next_on_free_list(_free_region_list);
4876 _free_region_list = r;
4877 _free_region_list_size++;
4878 assert(_free_region_list_size == free_region_list_length(), "Inv");
4879 }
4880
4881 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4882 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4883 put_free_region_on_list_locked(r);
4884 }
4885
4886 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4887 assert(ZF_mon->owned_by_self(), "precondition.");
4888 assert(_free_region_list_size == free_region_list_length(), "Inv");
4889 HeapRegion* res = _free_region_list;
4890 if (res != NULL) {
4891 _free_region_list = res->next_from_free_list();
4892 _free_region_list_size--;
4893 res->set_on_free_list(false);
4894 res->set_next_on_free_list(NULL);
4895 assert(_free_region_list_size == free_region_list_length(), "Inv");
4896 }
4897 return res;
4898 }
4899
4900
4901 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4902 // By self, or on behalf of self.
4903 assert(Heap_lock->is_locked(), "Precondition");
4904 HeapRegion* res = NULL;
4905 bool first = true;
4906 while (res == NULL) {
4907 if (zero_filled || !first) {
4908 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4909 res = pop_free_region_list_locked();
4910 if (res != NULL) {
4911 assert(!res->zero_fill_is_allocated(),
4912 "No allocated regions on free list.");
4913 res->set_zero_fill_allocated();
4914 } else if (!first) {
4915 break; // We tried both, time to return NULL.
4916 }
4917 }
4918
4919 if (res == NULL) {
4920 res = alloc_region_from_unclean_list(zero_filled);
4921 }
4922 assert(res == NULL ||
4923 !zero_filled ||
4924 res->zero_fill_is_allocated(),
4925 "We must have allocated the region we're returning");
4926 first = false;
4927 }
4928 return res;
4929 }
4930
4931 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4932 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4933 {
4934 HeapRegion* prev = NULL;
4935 HeapRegion* cur = _unclean_region_list.hd();
4936 while (cur != NULL) {
4937 HeapRegion* next = cur->next_from_unclean_list();
4938 if (cur->zero_fill_is_allocated()) {
4939 // Remove from the list.
4940 if (prev == NULL) {
4941 (void)_unclean_region_list.pop();
4942 } else {
4943 _unclean_region_list.delete_after(prev);
4944 }
4945 cur->set_on_unclean_list(false);
4946 cur->set_next_on_unclean_list(NULL);
4947 } else {
4948 prev = cur;
4949 }
4950 cur = next;
4951 }
4952 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4953 "Inv");
4954 }
4955
4956 {
4957 HeapRegion* prev = NULL;
4958 HeapRegion* cur = _free_region_list;
4959 while (cur != NULL) {
4960 HeapRegion* next = cur->next_from_free_list();
4961 if (cur->zero_fill_is_allocated()) {
4962 // Remove from the list.
4963 if (prev == NULL) {
4964 _free_region_list = cur->next_from_free_list();
4965 } else {
4966 prev->set_next_on_free_list(cur->next_from_free_list());
4967 }
4968 cur->set_on_free_list(false);
4969 cur->set_next_on_free_list(NULL);
4970 _free_region_list_size--;
4971 } else {
4972 prev = cur;
4973 }
4974 cur = next;
4975 }
4976 assert(_free_region_list_size == free_region_list_length(), "Inv");
4977 }
4978 }
4979
4980 bool G1CollectedHeap::verify_region_lists() {
4981 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4982 return verify_region_lists_locked();
4983 }
4984
4985 bool G1CollectedHeap::verify_region_lists_locked() {
4986 HeapRegion* unclean = _unclean_region_list.hd();
4987 while (unclean != NULL) {
4988 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4989 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4990 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4991 "Everything else is possible.");
4992 unclean = unclean->next_from_unclean_list();
4993 }
4994 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4995
4996 HeapRegion* free_r = _free_region_list;
4997 while (free_r != NULL) {
4998 assert(free_r->is_on_free_list(), "Well, it is!");
4999 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
5000 switch (free_r->zero_fill_state()) {
5001 case HeapRegion::NotZeroFilled:
5002 case HeapRegion::ZeroFilling:
5003 guarantee(false, "Should not be on free list.");
5004 break;
5005 default:
5006 // Everything else is possible.
5007 break;
5008 }
5009 free_r = free_r->next_from_free_list();
5010 }
5011 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
5012 // If we didn't do an assertion...
5013 return true;
5014 }
5015
5016 size_t G1CollectedHeap::free_region_list_length() {
5017 assert(ZF_mon->owned_by_self(), "precondition.");
5018 size_t len = 0;
5019 HeapRegion* cur = _free_region_list;
5020 while (cur != NULL) {
5021 len++;
5022 cur = cur->next_from_free_list();
5023 }
5024 return len;
5025 }
5026
5027 size_t G1CollectedHeap::unclean_region_list_length() {
5028 assert(ZF_mon->owned_by_self(), "precondition.");
5029 return _unclean_region_list.length();
5030 }
5031
5032 size_t G1CollectedHeap::n_regions() {
5033 return _hrs->length();
5034 }
5035
5036 size_t G1CollectedHeap::max_regions() {
5037 return
5038 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5039 HeapRegion::GrainBytes;
5040 }
5041
5042 size_t G1CollectedHeap::free_regions() {
5043 /* Possibly-expensive assert.
5044 assert(_free_regions == count_free_regions(),
5045 "_free_regions is off.");
5046 */
5047 return _free_regions;
5048 }
5049
5050 bool G1CollectedHeap::should_zf() {
5051 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5052 }
5053
5054 class RegionCounter: public HeapRegionClosure {
5055 size_t _n;
5056 public:
5057 RegionCounter() : _n(0) {}
5058 bool doHeapRegion(HeapRegion* r) {
5059 if (r->is_empty()) {
5060 assert(!r->isHumongous(), "H regions should not be empty.");
5061 _n++;
5062 }
5063 return false;
5064 }
5065 int res() { return (int) _n; }
5066 };
5067
5068 size_t G1CollectedHeap::count_free_regions() {
5069 RegionCounter rc;
5070 heap_region_iterate(&rc);
5071 size_t n = rc.res();
5072 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5073 n--;
5074 return n;
5075 }
5076
5077 size_t G1CollectedHeap::count_free_regions_list() {
5078 size_t n = 0;
5079 size_t o = 0;
5080 ZF_mon->lock_without_safepoint_check();
5081 HeapRegion* cur = _free_region_list;
5082 while (cur != NULL) {
5083 cur = cur->next_from_free_list();
5084 n++;
5085 }
5086 size_t m = unclean_region_list_length();
5087 ZF_mon->unlock();
5088 return n + m;
5089 }
5090
5091 bool G1CollectedHeap::should_set_young_locked() {
5092 assert(heap_lock_held_for_gc(),
5093 "the heap lock should already be held by or for this thread");
5094 return (g1_policy()->in_young_gc_mode() &&
5095 g1_policy()->should_add_next_region_to_young_list());
5096 }
5097
5098 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5099 assert(heap_lock_held_for_gc(),
5100 "the heap lock should already be held by or for this thread");
5101 _young_list->push_region(hr);
5102 g1_policy()->set_region_short_lived(hr);
5103 }
5104
5105 class NoYoungRegionsClosure: public HeapRegionClosure {
5106 private:
5107 bool _success;
5108 public:
5109 NoYoungRegionsClosure() : _success(true) { }
5110 bool doHeapRegion(HeapRegion* r) {
5111 if (r->is_young()) {
5112 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5113 r->bottom(), r->end());
5114 _success = false;
5115 }
5116 return false;
5117 }
5118 bool success() { return _success; }
5119 };
5120
5121 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5122 bool ret = _young_list->check_list_empty(check_sample);
5123
5124 if (check_heap) {
5125 NoYoungRegionsClosure closure;
5126 heap_region_iterate(&closure);
5127 ret = ret && closure.success();
5128 }
5129
5130 return ret;
5131 }
5132
5133 void G1CollectedHeap::empty_young_list() {
5134 assert(heap_lock_held_for_gc(),
5135 "the heap lock should already be held by or for this thread");
5136 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5137
5138 _young_list->empty_list();
5139 }
5140
5141 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5142 bool no_allocs = true;
5143 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5144 HeapRegion* r = _gc_alloc_regions[ap];
5145 no_allocs = r == NULL || r->saved_mark_at_top();
5146 }
5147 return no_allocs;
5148 }
5149
5150 void G1CollectedHeap::retire_all_alloc_regions() {
5151 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5152 HeapRegion* r = _gc_alloc_regions[ap];
5153 if (r != NULL) {
5154 // Check for aliases.
5155 bool has_processed_alias = false;
5156 for (int i = 0; i < ap; ++i) {
5157 if (_gc_alloc_regions[i] == r) {
5158 has_processed_alias = true;
5159 break;
5160 }
5161 }
5162 if (!has_processed_alias) {
5163 retire_alloc_region(r, false /* par */);
5164 }
5165 }
5166 }
5167 }
5168
5169
5170 // Done at the start of full GC.
5171 void G1CollectedHeap::tear_down_region_lists() {
5172 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5173 while (pop_unclean_region_list_locked() != NULL) ;
5174 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5175 "Postconditions of loop.");
5176 while (pop_free_region_list_locked() != NULL) ;
5177 assert(_free_region_list == NULL, "Postcondition of loop.");
5178 if (_free_region_list_size != 0) {
5179 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5180 print_on(gclog_or_tty, true /* extended */);
5181 }
5182 assert(_free_region_list_size == 0, "Postconditions of loop.");
5183 }
5184
5185
5186 class RegionResetter: public HeapRegionClosure {
5187 G1CollectedHeap* _g1;
5188 int _n;
5189 public:
5190 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5191 bool doHeapRegion(HeapRegion* r) {
5192 if (r->continuesHumongous()) return false;
5193 if (r->top() > r->bottom()) {
5194 if (r->top() < r->end()) {
5195 Copy::fill_to_words(r->top(),
5196 pointer_delta(r->end(), r->top()));
5197 }
5198 r->set_zero_fill_allocated();
5199 } else {
5200 assert(r->is_empty(), "tautology");
5201 _n++;
5202 switch (r->zero_fill_state()) {
5203 case HeapRegion::NotZeroFilled:
5204 case HeapRegion::ZeroFilling:
5205 _g1->put_region_on_unclean_list_locked(r);
5206 break;
5207 case HeapRegion::Allocated:
5208 r->set_zero_fill_complete();
5209 // no break; go on to put on free list.
5210 case HeapRegion::ZeroFilled:
5211 _g1->put_free_region_on_list_locked(r);
5212 break;
5213 }
5214 }
5215 return false;
5216 }
5217
5218 int getFreeRegionCount() {return _n;}
5219 };
5220
5221 // Done at the end of full GC.
5222 void G1CollectedHeap::rebuild_region_lists() {
5223 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5224 // This needs to go at the end of the full GC.
5225 RegionResetter rs;
5226 heap_region_iterate(&rs);
5227 _free_regions = rs.getFreeRegionCount();
5228 // Tell the ZF thread it may have work to do.
5229 if (should_zf()) ZF_mon->notify_all();
5230 }
5231
5232 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5233 G1CollectedHeap* _g1;
5234 int _n;
5235 public:
5236 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5237 bool doHeapRegion(HeapRegion* r) {
5238 if (r->continuesHumongous()) return false;
5239 if (r->top() > r->bottom()) {
5240 // There are assertions in "set_zero_fill_needed()" below that
5241 // require top() == bottom(), so this is technically illegal.
5242 // We'll skirt the law here, by making that true temporarily.
5243 DEBUG_ONLY(HeapWord* save_top = r->top();
5244 r->set_top(r->bottom()));
5245 r->set_zero_fill_needed();
5246 DEBUG_ONLY(r->set_top(save_top));
5247 }
5248 return false;
5249 }
5250 };
5251
5252 // Done at the start of full GC.
5253 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5254 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5255 // This needs to go at the end of the full GC.
5256 UsedRegionsNeedZeroFillSetter rs;
5257 heap_region_iterate(&rs);
5258 }
5259
5260 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5261 _refine_cte_cl->set_concurrent(concurrent);
5262 }
5263
5264 #ifndef PRODUCT
5265
5266 class PrintHeapRegionClosure: public HeapRegionClosure {
5267 public:
5268 bool doHeapRegion(HeapRegion *r) {
5269 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5270 if (r != NULL) {
5271 if (r->is_on_free_list())
5272 gclog_or_tty->print("Free ");
5273 if (r->is_young())
5274 gclog_or_tty->print("Young ");
5275 if (r->isHumongous())
5276 gclog_or_tty->print("Is Humongous ");
5277 r->print();
5278 }
5279 return false;
5280 }
5281 };
5282
5283 class SortHeapRegionClosure : public HeapRegionClosure {
5284 size_t young_regions,free_regions, unclean_regions;
5285 size_t hum_regions, count;
5286 size_t unaccounted, cur_unclean, cur_alloc;
5287 size_t total_free;
5288 HeapRegion* cur;
5289 public:
5290 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5291 free_regions(0), unclean_regions(0),
5292 hum_regions(0),
5293 count(0), unaccounted(0),
5294 cur_alloc(0), total_free(0)
5295 {}
5296 bool doHeapRegion(HeapRegion *r) {
5297 count++;
5298 if (r->is_on_free_list()) free_regions++;
5299 else if (r->is_on_unclean_list()) unclean_regions++;
5300 else if (r->isHumongous()) hum_regions++;
5301 else if (r->is_young()) young_regions++;
5302 else if (r == cur) cur_alloc++;
5303 else unaccounted++;
5304 return false;
5305 }
5306 void print() {
5307 total_free = free_regions + unclean_regions;
5308 gclog_or_tty->print("%d regions\n", count);
5309 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5310 total_free, free_regions, unclean_regions);
5311 gclog_or_tty->print("%d humongous %d young\n",
5312 hum_regions, young_regions);
5313 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5314 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5315 }
5316 };
5317
5318 void G1CollectedHeap::print_region_counts() {
5319 SortHeapRegionClosure sc(_cur_alloc_region);
5320 PrintHeapRegionClosure cl;
5321 heap_region_iterate(&cl);
5322 heap_region_iterate(&sc);
5323 sc.print();
5324 print_region_accounting_info();
5325 };
5326
5327 bool G1CollectedHeap::regions_accounted_for() {
5328 // TODO: regions accounting for young/survivor/tenured
5329 return true;
5330 }
5331
5332 bool G1CollectedHeap::print_region_accounting_info() {
5333 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5334 free_regions(),
5335 count_free_regions(), count_free_regions_list(),
5336 _free_region_list_size, _unclean_region_list.sz());
5337 gclog_or_tty->print_cr("cur_alloc: %d.",
5338 (_cur_alloc_region == NULL ? 0 : 1));
5339 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5340
5341 // TODO: check regions accounting for young/survivor/tenured
5342 return true;
5343 }
5344
5345 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5346 HeapRegion* hr = heap_region_containing(p);
5347 if (hr == NULL) {
5348 return is_in_permanent(p);
5349 } else {
5350 return hr->is_in(p);
5351 }
5352 }
5353 #endif // !PRODUCT
5354
5355 void G1CollectedHeap::g1_unimplemented() {
5356 // Unimplemented();
5357 }