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 "incls/_precompiled.incl"
26 #include "incls/_g1CollectedHeap.cpp.incl"
27
28 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
29
30 // turn it on so that the contents of the young list (scan-only /
31 // to-be-collected) are printed at "strategic" points before / during
32 // / after the collection --- this is useful for debugging
33 #define YOUNG_LIST_VERBOSE 0
34 // CURRENT STATUS
35 // This file is under construction. Search for "FIXME".
36
37 // INVARIANTS/NOTES
38 //
39 // All allocation activity covered by the G1CollectedHeap interface is
40 // serialized by acquiring the HeapLock. This happens in
41 // mem_allocate_work, which all such allocation functions call.
42 // (Note that this does not apply to TLAB allocation, which is not part
43 // of this interface: it is done by clients of this interface.)
44
45 // Local to this file.
46
47 class RefineCardTableEntryClosure: public CardTableEntryClosure {
48 SuspendibleThreadSet* _sts;
49 G1RemSet* _g1rs;
50 ConcurrentG1Refine* _cg1r;
51 bool _concurrent;
52 public:
53 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
54 G1RemSet* g1rs,
55 ConcurrentG1Refine* cg1r) :
56 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
57 {}
58 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
59 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
60 // This path is executed by the concurrent refine or mutator threads,
61 // concurrently, and so we do not care if card_ptr contains references
62 // that point into the collection set.
63 assert(!oops_into_cset, "should be");
64
65 if (_concurrent && _sts->should_yield()) {
66 // Caller will actually yield.
67 return false;
68 }
69 // Otherwise, we finished successfully; return true.
70 return true;
71 }
72 void set_concurrent(bool b) { _concurrent = b; }
73 };
74
75
76 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
77 int _calls;
78 G1CollectedHeap* _g1h;
79 CardTableModRefBS* _ctbs;
80 int _histo[256];
81 public:
82 ClearLoggedCardTableEntryClosure() :
83 _calls(0)
84 {
85 _g1h = G1CollectedHeap::heap();
86 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
87 for (int i = 0; i < 256; i++) _histo[i] = 0;
88 }
89 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
90 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
91 _calls++;
92 unsigned char* ujb = (unsigned char*)card_ptr;
93 int ind = (int)(*ujb);
94 _histo[ind]++;
95 *card_ptr = -1;
96 }
97 return true;
98 }
99 int calls() { return _calls; }
100 void print_histo() {
101 gclog_or_tty->print_cr("Card table value histogram:");
102 for (int i = 0; i < 256; i++) {
103 if (_histo[i] != 0) {
104 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
105 }
106 }
107 }
108 };
109
110 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
111 int _calls;
112 G1CollectedHeap* _g1h;
113 CardTableModRefBS* _ctbs;
114 public:
115 RedirtyLoggedCardTableEntryClosure() :
116 _calls(0)
117 {
118 _g1h = G1CollectedHeap::heap();
119 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
120 }
121 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
122 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
123 _calls++;
124 *card_ptr = 0;
125 }
126 return true;
127 }
128 int calls() { return _calls; }
129 };
130
131 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
132 public:
133 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
134 *card_ptr = CardTableModRefBS::dirty_card_val();
135 return true;
136 }
137 };
138
139 YoungList::YoungList(G1CollectedHeap* g1h)
140 : _g1h(g1h), _head(NULL),
141 _length(0),
142 _last_sampled_rs_lengths(0),
143 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
144 {
145 guarantee( check_list_empty(false), "just making sure..." );
146 }
147
148 void YoungList::push_region(HeapRegion *hr) {
149 assert(!hr->is_young(), "should not already be young");
150 assert(hr->get_next_young_region() == NULL, "cause it should!");
151
152 hr->set_next_young_region(_head);
153 _head = hr;
154
155 hr->set_young();
156 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
157 ++_length;
158 }
159
160 void YoungList::add_survivor_region(HeapRegion* hr) {
161 assert(hr->is_survivor(), "should be flagged as survivor region");
162 assert(hr->get_next_young_region() == NULL, "cause it should!");
163
164 hr->set_next_young_region(_survivor_head);
165 if (_survivor_head == NULL) {
166 _survivor_tail = hr;
167 }
168 _survivor_head = hr;
169
170 ++_survivor_length;
171 }
172
173 void YoungList::empty_list(HeapRegion* list) {
174 while (list != NULL) {
175 HeapRegion* next = list->get_next_young_region();
176 list->set_next_young_region(NULL);
177 list->uninstall_surv_rate_group();
178 list->set_not_young();
179 list = next;
180 }
181 }
182
183 void YoungList::empty_list() {
184 assert(check_list_well_formed(), "young list should be well formed");
185
186 empty_list(_head);
187 _head = NULL;
188 _length = 0;
189
190 empty_list(_survivor_head);
191 _survivor_head = NULL;
192 _survivor_tail = NULL;
193 _survivor_length = 0;
194
195 _last_sampled_rs_lengths = 0;
196
197 assert(check_list_empty(false), "just making sure...");
198 }
199
200 bool YoungList::check_list_well_formed() {
201 bool ret = true;
202
203 size_t length = 0;
204 HeapRegion* curr = _head;
205 HeapRegion* last = NULL;
206 while (curr != NULL) {
207 if (!curr->is_young()) {
208 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
209 "incorrectly tagged (y: %d, surv: %d)",
210 curr->bottom(), curr->end(),
211 curr->is_young(), curr->is_survivor());
212 ret = false;
213 }
214 ++length;
215 last = curr;
216 curr = curr->get_next_young_region();
217 }
218 ret = ret && (length == _length);
219
220 if (!ret) {
221 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
222 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
223 length, _length);
224 }
225
226 return ret;
227 }
228
229 bool YoungList::check_list_empty(bool check_sample) {
230 bool ret = true;
231
232 if (_length != 0) {
233 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
234 _length);
235 ret = false;
236 }
237 if (check_sample && _last_sampled_rs_lengths != 0) {
238 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
239 ret = false;
240 }
241 if (_head != NULL) {
242 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
243 ret = false;
244 }
245 if (!ret) {
246 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
247 }
248
249 return ret;
250 }
251
252 void
253 YoungList::rs_length_sampling_init() {
254 _sampled_rs_lengths = 0;
255 _curr = _head;
256 }
257
258 bool
259 YoungList::rs_length_sampling_more() {
260 return _curr != NULL;
261 }
262
263 void
264 YoungList::rs_length_sampling_next() {
265 assert( _curr != NULL, "invariant" );
266 size_t rs_length = _curr->rem_set()->occupied();
267
268 _sampled_rs_lengths += rs_length;
269
270 // The current region may not yet have been added to the
271 // incremental collection set (it gets added when it is
272 // retired as the current allocation region).
273 if (_curr->in_collection_set()) {
274 // Update the collection set policy information for this region
275 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
276 }
277
278 _curr = _curr->get_next_young_region();
279 if (_curr == NULL) {
280 _last_sampled_rs_lengths = _sampled_rs_lengths;
281 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
282 }
283 }
284
285 void
286 YoungList::reset_auxilary_lists() {
287 guarantee( is_empty(), "young list should be empty" );
288 assert(check_list_well_formed(), "young list should be well formed");
289
290 // Add survivor regions to SurvRateGroup.
291 _g1h->g1_policy()->note_start_adding_survivor_regions();
292 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
293
294 for (HeapRegion* curr = _survivor_head;
295 curr != NULL;
296 curr = curr->get_next_young_region()) {
297 _g1h->g1_policy()->set_region_survivors(curr);
298
299 // The region is a non-empty survivor so let's add it to
300 // the incremental collection set for the next evacuation
301 // pause.
302 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
303 }
304 _g1h->g1_policy()->note_stop_adding_survivor_regions();
305
306 _head = _survivor_head;
307 _length = _survivor_length;
308 if (_survivor_head != NULL) {
309 assert(_survivor_tail != NULL, "cause it shouldn't be");
310 assert(_survivor_length > 0, "invariant");
311 _survivor_tail->set_next_young_region(NULL);
312 }
313
314 // Don't clear the survivor list handles until the start of
315 // the next evacuation pause - we need it in order to re-tag
316 // the survivor regions from this evacuation pause as 'young'
317 // at the start of the next.
318
319 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
320
321 assert(check_list_well_formed(), "young list should be well formed");
322 }
323
324 void YoungList::print() {
325 HeapRegion* lists[] = {_head, _survivor_head};
326 const char* names[] = {"YOUNG", "SURVIVOR"};
327
328 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
329 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
330 HeapRegion *curr = lists[list];
331 if (curr == NULL)
332 gclog_or_tty->print_cr(" empty");
333 while (curr != NULL) {
334 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
335 "age: %4d, y: %d, surv: %d",
336 curr->bottom(), curr->end(),
337 curr->top(),
338 curr->prev_top_at_mark_start(),
339 curr->next_top_at_mark_start(),
340 curr->top_at_conc_mark_count(),
341 curr->age_in_surv_rate_group_cond(),
342 curr->is_young(),
343 curr->is_survivor());
344 curr = curr->get_next_young_region();
345 }
346 }
347
348 gclog_or_tty->print_cr("");
349 }
350
351 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
352 {
353 // Claim the right to put the region on the dirty cards region list
354 // by installing a self pointer.
355 HeapRegion* next = hr->get_next_dirty_cards_region();
356 if (next == NULL) {
357 HeapRegion* res = (HeapRegion*)
358 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
359 NULL);
360 if (res == NULL) {
361 HeapRegion* head;
362 do {
363 // Put the region to the dirty cards region list.
364 head = _dirty_cards_region_list;
365 next = (HeapRegion*)
366 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
367 if (next == head) {
368 assert(hr->get_next_dirty_cards_region() == hr,
369 "hr->get_next_dirty_cards_region() != hr");
370 if (next == NULL) {
371 // The last region in the list points to itself.
372 hr->set_next_dirty_cards_region(hr);
373 } else {
374 hr->set_next_dirty_cards_region(next);
375 }
376 }
377 } while (next != head);
378 }
379 }
380 }
381
382 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
383 {
384 HeapRegion* head;
385 HeapRegion* hr;
386 do {
387 head = _dirty_cards_region_list;
388 if (head == NULL) {
389 return NULL;
390 }
391 HeapRegion* new_head = head->get_next_dirty_cards_region();
392 if (head == new_head) {
393 // The last region.
394 new_head = NULL;
395 }
396 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
397 head);
398 } while (hr != head);
399 assert(hr != NULL, "invariant");
400 hr->set_next_dirty_cards_region(NULL);
401 return hr;
402 }
403
404 void G1CollectedHeap::stop_conc_gc_threads() {
405 _cg1r->stop();
406 _czft->stop();
407 _cmThread->stop();
408 }
409
410
411 void G1CollectedHeap::check_ct_logs_at_safepoint() {
412 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
413 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
414
415 // Count the dirty cards at the start.
416 CountNonCleanMemRegionClosure count1(this);
417 ct_bs->mod_card_iterate(&count1);
418 int orig_count = count1.n();
419
420 // First clear the logged cards.
421 ClearLoggedCardTableEntryClosure clear;
422 dcqs.set_closure(&clear);
423 dcqs.apply_closure_to_all_completed_buffers();
424 dcqs.iterate_closure_all_threads(false);
425 clear.print_histo();
426
427 // Now ensure that there's no dirty cards.
428 CountNonCleanMemRegionClosure count2(this);
429 ct_bs->mod_card_iterate(&count2);
430 if (count2.n() != 0) {
431 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
432 count2.n(), orig_count);
433 }
434 guarantee(count2.n() == 0, "Card table should be clean.");
435
436 RedirtyLoggedCardTableEntryClosure redirty;
437 JavaThread::dirty_card_queue_set().set_closure(&redirty);
438 dcqs.apply_closure_to_all_completed_buffers();
439 dcqs.iterate_closure_all_threads(false);
440 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
441 clear.calls(), orig_count);
442 guarantee(redirty.calls() == clear.calls(),
443 "Or else mechanism is broken.");
444
445 CountNonCleanMemRegionClosure count3(this);
446 ct_bs->mod_card_iterate(&count3);
447 if (count3.n() != orig_count) {
448 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
449 orig_count, count3.n());
450 guarantee(count3.n() >= orig_count, "Should have restored them all.");
451 }
452
453 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
454 }
455
456 // Private class members.
457
458 G1CollectedHeap* G1CollectedHeap::_g1h;
459
460 // Private methods.
461
462 // Finds a HeapRegion that can be used to allocate a given size of block.
463
464
465 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
466 bool do_expand,
467 bool zero_filled) {
468 ConcurrentZFThread::note_region_alloc();
469 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
470 if (res == NULL && do_expand) {
471 expand(word_size * HeapWordSize);
472 res = alloc_free_region_from_lists(zero_filled);
473 assert(res == NULL ||
474 (!res->isHumongous() &&
475 (!zero_filled ||
476 res->zero_fill_state() == HeapRegion::Allocated)),
477 "Alloc Regions must be zero filled (and non-H)");
478 }
479 if (res != NULL) {
480 if (res->is_empty()) {
481 _free_regions--;
482 }
483 assert(!res->isHumongous() &&
484 (!zero_filled || res->zero_fill_state() == HeapRegion::Allocated),
485 err_msg("Non-young alloc Regions must be zero filled (and non-H):"
486 " res->isHumongous()=%d, zero_filled=%d, res->zero_fill_state()=%d",
487 res->isHumongous(), zero_filled, res->zero_fill_state()));
488 assert(!res->is_on_unclean_list(),
489 "Alloc Regions must not be on the unclean list");
490 if (G1PrintHeapRegions) {
491 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
492 "top "PTR_FORMAT,
493 res->hrs_index(), res->bottom(), res->end(), res->top());
494 }
495 }
496 return res;
497 }
498
499 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
500 size_t word_size,
501 bool zero_filled) {
502 HeapRegion* alloc_region = NULL;
503 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
504 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
505 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
506 alloc_region->set_survivor();
507 }
508 ++_gc_alloc_region_counts[purpose];
509 } else {
510 g1_policy()->note_alloc_region_limit_reached(purpose);
511 }
512 return alloc_region;
513 }
514
515 // If could fit into free regions w/o expansion, try.
516 // Otherwise, if can expand, do so.
517 // Otherwise, if using ex regions might help, try with ex given back.
518 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
519 assert(regions_accounted_for(), "Region leakage!");
520
521 // We can't allocate H regions while cleanupComplete is running, since
522 // some of the regions we find to be empty might not yet be added to the
523 // unclean list. (If we're already at a safepoint, this call is
524 // unnecessary, not to mention wrong.)
525 if (!SafepointSynchronize::is_at_safepoint())
526 wait_for_cleanup_complete();
527
528 size_t num_regions =
529 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
530
531 // Special case if < one region???
532
533 // Remember the ft size.
534 size_t x_size = expansion_regions();
535
536 HeapWord* res = NULL;
537 bool eliminated_allocated_from_lists = false;
538
539 // Can the allocation potentially fit in the free regions?
540 if (free_regions() >= num_regions) {
541 res = _hrs->obj_allocate(word_size);
542 }
543 if (res == NULL) {
544 // Try expansion.
545 size_t fs = _hrs->free_suffix();
546 if (fs + x_size >= num_regions) {
547 expand((num_regions - fs) * HeapRegion::GrainBytes);
548 res = _hrs->obj_allocate(word_size);
549 assert(res != NULL, "This should have worked.");
550 } else {
551 // Expansion won't help. Are there enough free regions if we get rid
552 // of reservations?
553 size_t avail = free_regions();
554 if (avail >= num_regions) {
555 res = _hrs->obj_allocate(word_size);
556 if (res != NULL) {
557 remove_allocated_regions_from_lists();
558 eliminated_allocated_from_lists = true;
559 }
560 }
561 }
562 }
563 if (res != NULL) {
564 // Increment by the number of regions allocated.
565 // FIXME: Assumes regions all of size GrainBytes.
566 #ifndef PRODUCT
567 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
568 HeapRegion::GrainWords));
569 #endif
570 if (!eliminated_allocated_from_lists)
571 remove_allocated_regions_from_lists();
572 _summary_bytes_used += word_size * HeapWordSize;
573 _free_regions -= num_regions;
574 _num_humongous_regions += (int) num_regions;
575 }
576 assert(regions_accounted_for(), "Region Leakage");
577 return res;
578 }
579
580 HeapWord*
581 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
582 bool permit_collection_pause) {
583 HeapWord* res = NULL;
584 HeapRegion* allocated_young_region = NULL;
585
586 assert( SafepointSynchronize::is_at_safepoint() ||
587 Heap_lock->owned_by_self(), "pre condition of the call" );
588
589 if (isHumongous(word_size)) {
590 // Allocation of a humongous object can, in a sense, complete a
591 // partial region, if the previous alloc was also humongous, and
592 // caused the test below to succeed.
593 if (permit_collection_pause)
594 do_collection_pause_if_appropriate(word_size);
595 res = humongousObjAllocate(word_size);
596 assert(_cur_alloc_region == NULL
597 || !_cur_alloc_region->isHumongous(),
598 "Prevent a regression of this bug.");
599
600 } else {
601 // We may have concurrent cleanup working at the time. Wait for it
602 // to complete. In the future we would probably want to make the
603 // concurrent cleanup truly concurrent by decoupling it from the
604 // allocation.
605 if (!SafepointSynchronize::is_at_safepoint())
606 wait_for_cleanup_complete();
607 // If we do a collection pause, this will be reset to a non-NULL
608 // value. If we don't, nulling here ensures that we allocate a new
609 // region below.
610 if (_cur_alloc_region != NULL) {
611 // We're finished with the _cur_alloc_region.
612 // As we're builing (at least the young portion) of the collection
613 // set incrementally we'll add the current allocation region to
614 // the collection set here.
615 if (_cur_alloc_region->is_young()) {
616 g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
617 }
618 _summary_bytes_used += _cur_alloc_region->used();
619 _cur_alloc_region = NULL;
620 }
621 assert(_cur_alloc_region == NULL, "Invariant.");
622 // Completion of a heap region is perhaps a good point at which to do
623 // a collection pause.
624 if (permit_collection_pause)
625 do_collection_pause_if_appropriate(word_size);
626 // Make sure we have an allocation region available.
627 if (_cur_alloc_region == NULL) {
628 if (!SafepointSynchronize::is_at_safepoint())
629 wait_for_cleanup_complete();
630 bool next_is_young = should_set_young_locked();
631 // If the next region is not young, make sure it's zero-filled.
632 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
633 if (_cur_alloc_region != NULL) {
634 _summary_bytes_used -= _cur_alloc_region->used();
635 if (next_is_young) {
636 set_region_short_lived_locked(_cur_alloc_region);
637 allocated_young_region = _cur_alloc_region;
638 }
639 }
640 }
641 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
642 "Prevent a regression of this bug.");
643
644 // Now retry the allocation.
645 if (_cur_alloc_region != NULL) {
646 if (allocated_young_region != NULL) {
647 // We need to ensure that the store to top does not
648 // float above the setting of the young type.
649 OrderAccess::storestore();
650 }
651 res = _cur_alloc_region->allocate(word_size);
652 }
653 }
654
655 // NOTE: fails frequently in PRT
656 assert(regions_accounted_for(), "Region leakage!");
657
658 if (res != NULL) {
659 if (!SafepointSynchronize::is_at_safepoint()) {
660 assert( permit_collection_pause, "invariant" );
661 assert( Heap_lock->owned_by_self(), "invariant" );
662 Heap_lock->unlock();
663 }
664
665 if (allocated_young_region != NULL) {
666 HeapRegion* hr = allocated_young_region;
667 HeapWord* bottom = hr->bottom();
668 HeapWord* end = hr->end();
669 MemRegion mr(bottom, end);
670 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
671 }
672 }
673
674 assert( SafepointSynchronize::is_at_safepoint() ||
675 (res == NULL && Heap_lock->owned_by_self()) ||
676 (res != NULL && !Heap_lock->owned_by_self()),
677 "post condition of the call" );
678
679 return res;
680 }
681
682 HeapWord*
683 G1CollectedHeap::mem_allocate(size_t word_size,
684 bool is_noref,
685 bool is_tlab,
686 bool* gc_overhead_limit_was_exceeded) {
687 debug_only(check_for_valid_allocation_state());
688 assert(no_gc_in_progress(), "Allocation during gc not allowed");
689 HeapWord* result = NULL;
690
691 // Loop until the allocation is satisified,
692 // or unsatisfied after GC.
693 for (int try_count = 1; /* return or throw */; try_count += 1) {
694 int gc_count_before;
695 {
696 Heap_lock->lock();
697 result = attempt_allocation(word_size);
698 if (result != NULL) {
699 // attempt_allocation should have unlocked the heap lock
700 assert(is_in(result), "result not in heap");
701 return result;
702 }
703 // Read the gc count while the heap lock is held.
704 gc_count_before = SharedHeap::heap()->total_collections();
705 Heap_lock->unlock();
706 }
707
708 // Create the garbage collection operation...
709 VM_G1CollectForAllocation op(word_size,
710 gc_count_before);
711
712 // ...and get the VM thread to execute it.
713 VMThread::execute(&op);
714 if (op.prologue_succeeded()) {
715 result = op.result();
716 assert(result == NULL || is_in(result), "result not in heap");
717 return result;
718 }
719
720 // Give a warning if we seem to be looping forever.
721 if ((QueuedAllocationWarningCount > 0) &&
722 (try_count % QueuedAllocationWarningCount == 0)) {
723 warning("G1CollectedHeap::mem_allocate_work retries %d times",
724 try_count);
725 }
726 }
727 }
728
729 void G1CollectedHeap::abandon_cur_alloc_region() {
730 if (_cur_alloc_region != NULL) {
731 // We're finished with the _cur_alloc_region.
732 if (_cur_alloc_region->is_empty()) {
733 _free_regions++;
734 free_region(_cur_alloc_region);
735 } else {
736 // As we're builing (at least the young portion) of the collection
737 // set incrementally we'll add the current allocation region to
738 // the collection set here.
739 if (_cur_alloc_region->is_young()) {
740 g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
741 }
742 _summary_bytes_used += _cur_alloc_region->used();
743 }
744 _cur_alloc_region = NULL;
745 }
746 }
747
748 void G1CollectedHeap::abandon_gc_alloc_regions() {
749 // first, make sure that the GC alloc region list is empty (it should!)
750 assert(_gc_alloc_region_list == NULL, "invariant");
751 release_gc_alloc_regions(true /* totally */);
752 }
753
754 class PostMCRemSetClearClosure: public HeapRegionClosure {
755 ModRefBarrierSet* _mr_bs;
756 public:
757 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
758 bool doHeapRegion(HeapRegion* r) {
759 r->reset_gc_time_stamp();
760 if (r->continuesHumongous())
761 return false;
762 HeapRegionRemSet* hrrs = r->rem_set();
763 if (hrrs != NULL) hrrs->clear();
764 // You might think here that we could clear just the cards
765 // corresponding to the used region. But no: if we leave a dirty card
766 // in a region we might allocate into, then it would prevent that card
767 // from being enqueued, and cause it to be missed.
768 // Re: the performance cost: we shouldn't be doing full GC anyway!
769 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
770 return false;
771 }
772 };
773
774
775 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
776 ModRefBarrierSet* _mr_bs;
777 public:
778 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
779 bool doHeapRegion(HeapRegion* r) {
780 if (r->continuesHumongous()) return false;
781 if (r->used_region().word_size() != 0) {
782 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
783 }
784 return false;
785 }
786 };
787
788 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
789 G1CollectedHeap* _g1h;
790 UpdateRSOopClosure _cl;
791 int _worker_i;
792 public:
793 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
794 _cl(g1->g1_rem_set(), worker_i),
795 _worker_i(worker_i),
796 _g1h(g1)
797 { }
798 bool doHeapRegion(HeapRegion* r) {
799 if (!r->continuesHumongous()) {
800 _cl.set_from(r);
801 r->oop_iterate(&_cl);
802 }
803 return false;
804 }
805 };
806
807 class ParRebuildRSTask: public AbstractGangTask {
808 G1CollectedHeap* _g1;
809 public:
810 ParRebuildRSTask(G1CollectedHeap* g1)
811 : AbstractGangTask("ParRebuildRSTask"),
812 _g1(g1)
813 { }
814
815 void work(int i) {
816 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
817 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
818 HeapRegion::RebuildRSClaimValue);
819 }
820 };
821
822 void G1CollectedHeap::do_collection(bool explicit_gc,
823 bool clear_all_soft_refs,
824 size_t word_size) {
825 if (GC_locker::check_active_before_gc()) {
826 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
827 }
828
829 ResourceMark rm;
830
831 if (PrintHeapAtGC) {
832 Universe::print_heap_before_gc();
833 }
834
835 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
836 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
837
838 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
839 collector_policy()->should_clear_all_soft_refs();
840
841 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
842
843 {
844 IsGCActiveMark x;
845
846 // Timing
847 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
848 assert(!system_gc || explicit_gc, "invariant");
849 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
850 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
851 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
852 PrintGC, true, gclog_or_tty);
853
854 TraceMemoryManagerStats tms(true /* fullGC */);
855
856 double start = os::elapsedTime();
857 g1_policy()->record_full_collection_start();
858
859 gc_prologue(true);
860 increment_total_collections(true /* full gc */);
861
862 size_t g1h_prev_used = used();
863 assert(used() == recalculate_used(), "Should be equal");
864
865 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
866 HandleMark hm; // Discard invalid handles created during verification
867 prepare_for_verify();
868 gclog_or_tty->print(" VerifyBeforeGC:");
869 Universe::verify(true);
870 }
871 assert(regions_accounted_for(), "Region leakage!");
872
873 COMPILER2_PRESENT(DerivedPointerTable::clear());
874
875 // We want to discover references, but not process them yet.
876 // This mode is disabled in
877 // instanceRefKlass::process_discovered_references if the
878 // generation does some collection work, or
879 // instanceRefKlass::enqueue_discovered_references if the
880 // generation returns without doing any work.
881 ref_processor()->disable_discovery();
882 ref_processor()->abandon_partial_discovery();
883 ref_processor()->verify_no_references_recorded();
884
885 // Abandon current iterations of concurrent marking and concurrent
886 // refinement, if any are in progress.
887 concurrent_mark()->abort();
888
889 // Make sure we'll choose a new allocation region afterwards.
890 abandon_cur_alloc_region();
891 abandon_gc_alloc_regions();
892 assert(_cur_alloc_region == NULL, "Invariant.");
893 g1_rem_set()->cleanupHRRS();
894 tear_down_region_lists();
895 set_used_regions_to_need_zero_fill();
896
897 // We may have added regions to the current incremental collection
898 // set between the last GC or pause and now. We need to clear the
899 // incremental collection set and then start rebuilding it afresh
900 // after this full GC.
901 abandon_collection_set(g1_policy()->inc_cset_head());
902 g1_policy()->clear_incremental_cset();
903 g1_policy()->stop_incremental_cset_building();
904
905 if (g1_policy()->in_young_gc_mode()) {
906 empty_young_list();
907 g1_policy()->set_full_young_gcs(true);
908 }
909
910 // Temporarily make reference _discovery_ single threaded (non-MT).
911 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
912
913 // Temporarily make refs discovery atomic
914 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
915
916 // Temporarily clear _is_alive_non_header
917 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
918
919 ref_processor()->enable_discovery();
920 ref_processor()->setup_policy(do_clear_all_soft_refs);
921
922 // Do collection work
923 {
924 HandleMark hm; // Discard invalid handles created during gc
925 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
926 }
927 // Because freeing humongous regions may have added some unclean
928 // regions, it is necessary to tear down again before rebuilding.
929 tear_down_region_lists();
930 rebuild_region_lists();
931
932 _summary_bytes_used = recalculate_used();
933
934 ref_processor()->enqueue_discovered_references();
935
936 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
937
938 MemoryService::track_memory_usage();
939
940 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
941 HandleMark hm; // Discard invalid handles created during verification
942 gclog_or_tty->print(" VerifyAfterGC:");
943 prepare_for_verify();
944 Universe::verify(false);
945 }
946 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
947
948 reset_gc_time_stamp();
949 // Since everything potentially moved, we will clear all remembered
950 // sets, and clear all cards. Later we will rebuild remebered
951 // sets. We will also reset the GC time stamps of the regions.
952 PostMCRemSetClearClosure rs_clear(mr_bs());
953 heap_region_iterate(&rs_clear);
954
955 // Resize the heap if necessary.
956 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
957
958 if (_cg1r->use_cache()) {
959 _cg1r->clear_and_record_card_counts();
960 _cg1r->clear_hot_cache();
961 }
962
963 // Rebuild remembered sets of all regions.
964
965 if (G1CollectedHeap::use_parallel_gc_threads()) {
966 ParRebuildRSTask rebuild_rs_task(this);
967 assert(check_heap_region_claim_values(
968 HeapRegion::InitialClaimValue), "sanity check");
969 set_par_threads(workers()->total_workers());
970 workers()->run_task(&rebuild_rs_task);
971 set_par_threads(0);
972 assert(check_heap_region_claim_values(
973 HeapRegion::RebuildRSClaimValue), "sanity check");
974 reset_heap_region_claim_values();
975 } else {
976 RebuildRSOutOfRegionClosure rebuild_rs(this);
977 heap_region_iterate(&rebuild_rs);
978 }
979
980 if (PrintGC) {
981 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
982 }
983
984 if (true) { // FIXME
985 // Ask the permanent generation to adjust size for full collections
986 perm()->compute_new_size();
987 }
988
989 // Start a new incremental collection set for the next pause
990 assert(g1_policy()->collection_set() == NULL, "must be");
991 g1_policy()->start_incremental_cset_building();
992
993 // Clear the _cset_fast_test bitmap in anticipation of adding
994 // regions to the incremental collection set for the next
995 // evacuation pause.
996 clear_cset_fast_test();
997
998 double end = os::elapsedTime();
999 g1_policy()->record_full_collection_end();
1000
1001 #ifdef TRACESPINNING
1002 ParallelTaskTerminator::print_termination_counts();
1003 #endif
1004
1005 gc_epilogue(true);
1006
1007 // Discard all rset updates
1008 JavaThread::dirty_card_queue_set().abandon_logs();
1009 assert(!G1DeferredRSUpdate
1010 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1011 assert(regions_accounted_for(), "Region leakage!");
1012 }
1013
1014 if (g1_policy()->in_young_gc_mode()) {
1015 _young_list->reset_sampled_info();
1016 // At this point there should be no regions in the
1017 // entire heap tagged as young.
1018 assert( check_young_list_empty(true /* check_heap */),
1019 "young list should be empty at this point");
1020 }
1021
1022 // Update the number of full collections that have been completed.
1023 increment_full_collections_completed(false /* outer */);
1024
1025 if (PrintHeapAtGC) {
1026 Universe::print_heap_after_gc();
1027 }
1028 }
1029
1030 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1031 do_collection(true, /* explicit_gc */
1032 clear_all_soft_refs,
1033 0 /* word_size */);
1034 }
1035
1036 // This code is mostly copied from TenuredGeneration.
1037 void
1038 G1CollectedHeap::
1039 resize_if_necessary_after_full_collection(size_t word_size) {
1040 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1041
1042 // Include the current allocation, if any, and bytes that will be
1043 // pre-allocated to support collections, as "used".
1044 const size_t used_after_gc = used();
1045 const size_t capacity_after_gc = capacity();
1046 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1047
1048 // This is enforced in arguments.cpp.
1049 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1050 "otherwise the code below doesn't make sense");
1051
1052 // We don't have floating point command-line arguments
1053 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1054 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1055 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1056 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1057
1058 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1059 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1060
1061 // We have to be careful here as these two calculations can overflow
1062 // 32-bit size_t's.
1063 double used_after_gc_d = (double) used_after_gc;
1064 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1065 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1066
1067 // Let's make sure that they are both under the max heap size, which
1068 // by default will make them fit into a size_t.
1069 double desired_capacity_upper_bound = (double) max_heap_size;
1070 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1071 desired_capacity_upper_bound);
1072 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1073 desired_capacity_upper_bound);
1074
1075 // We can now safely turn them into size_t's.
1076 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1077 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1078
1079 // This assert only makes sense here, before we adjust them
1080 // with respect to the min and max heap size.
1081 assert(minimum_desired_capacity <= maximum_desired_capacity,
1082 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1083 "maximum_desired_capacity = "SIZE_FORMAT,
1084 minimum_desired_capacity, maximum_desired_capacity));
1085
1086 // Should not be greater than the heap max size. No need to adjust
1087 // it with respect to the heap min size as it's a lower bound (i.e.,
1088 // we'll try to make the capacity larger than it, not smaller).
1089 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1090 // Should not be less than the heap min size. No need to adjust it
1091 // with respect to the heap max size as it's an upper bound (i.e.,
1092 // we'll try to make the capacity smaller than it, not greater).
1093 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1094
1095 if (PrintGC && Verbose) {
1096 const double free_percentage =
1097 (double) free_after_gc / (double) capacity_after_gc;
1098 gclog_or_tty->print_cr("Computing new size after full GC ");
1099 gclog_or_tty->print_cr(" "
1100 " minimum_free_percentage: %6.2f",
1101 minimum_free_percentage);
1102 gclog_or_tty->print_cr(" "
1103 " maximum_free_percentage: %6.2f",
1104 maximum_free_percentage);
1105 gclog_or_tty->print_cr(" "
1106 " capacity: %6.1fK"
1107 " minimum_desired_capacity: %6.1fK"
1108 " maximum_desired_capacity: %6.1fK",
1109 (double) capacity_after_gc / (double) K,
1110 (double) minimum_desired_capacity / (double) K,
1111 (double) maximum_desired_capacity / (double) K);
1112 gclog_or_tty->print_cr(" "
1113 " free_after_gc: %6.1fK"
1114 " used_after_gc: %6.1fK",
1115 (double) free_after_gc / (double) K,
1116 (double) used_after_gc / (double) K);
1117 gclog_or_tty->print_cr(" "
1118 " free_percentage: %6.2f",
1119 free_percentage);
1120 }
1121 if (capacity_after_gc < minimum_desired_capacity) {
1122 // Don't expand unless it's significant
1123 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1124 expand(expand_bytes);
1125 if (PrintGC && Verbose) {
1126 gclog_or_tty->print_cr(" "
1127 " expanding:"
1128 " max_heap_size: %6.1fK"
1129 " minimum_desired_capacity: %6.1fK"
1130 " expand_bytes: %6.1fK",
1131 (double) max_heap_size / (double) K,
1132 (double) minimum_desired_capacity / (double) K,
1133 (double) expand_bytes / (double) K);
1134 }
1135
1136 // No expansion, now see if we want to shrink
1137 } else if (capacity_after_gc > maximum_desired_capacity) {
1138 // Capacity too large, compute shrinking size
1139 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1140 shrink(shrink_bytes);
1141 if (PrintGC && Verbose) {
1142 gclog_or_tty->print_cr(" "
1143 " shrinking:"
1144 " min_heap_size: %6.1fK"
1145 " maximum_desired_capacity: %6.1fK"
1146 " shrink_bytes: %6.1fK",
1147 (double) min_heap_size / (double) K,
1148 (double) maximum_desired_capacity / (double) K,
1149 (double) shrink_bytes / (double) K);
1150 }
1151 }
1152 }
1153
1154
1155 HeapWord*
1156 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1157 HeapWord* result = NULL;
1158
1159 // In a G1 heap, we're supposed to keep allocation from failing by
1160 // incremental pauses. Therefore, at least for now, we'll favor
1161 // expansion over collection. (This might change in the future if we can
1162 // do something smarter than full collection to satisfy a failed alloc.)
1163
1164 result = expand_and_allocate(word_size);
1165 if (result != NULL) {
1166 assert(is_in(result), "result not in heap");
1167 return result;
1168 }
1169
1170 // OK, I guess we have to try collection.
1171
1172 do_collection(false, false, word_size);
1173
1174 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1175
1176 if (result != NULL) {
1177 assert(is_in(result), "result not in heap");
1178 return result;
1179 }
1180
1181 // Try collecting soft references.
1182 do_collection(false, true, word_size);
1183 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1184 if (result != NULL) {
1185 assert(is_in(result), "result not in heap");
1186 return result;
1187 }
1188
1189 assert(!collector_policy()->should_clear_all_soft_refs(),
1190 "Flag should have been handled and cleared prior to this point");
1191
1192 // What else? We might try synchronous finalization later. If the total
1193 // space available is large enough for the allocation, then a more
1194 // complete compaction phase than we've tried so far might be
1195 // appropriate.
1196 return NULL;
1197 }
1198
1199 // Attempting to expand the heap sufficiently
1200 // to support an allocation of the given "word_size". If
1201 // successful, perform the allocation and return the address of the
1202 // allocated block, or else "NULL".
1203
1204 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1205 size_t expand_bytes = word_size * HeapWordSize;
1206 if (expand_bytes < MinHeapDeltaBytes) {
1207 expand_bytes = MinHeapDeltaBytes;
1208 }
1209 expand(expand_bytes);
1210 assert(regions_accounted_for(), "Region leakage!");
1211 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1212 return result;
1213 }
1214
1215 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1216 size_t pre_used = 0;
1217 size_t cleared_h_regions = 0;
1218 size_t freed_regions = 0;
1219 UncleanRegionList local_list;
1220 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1221 freed_regions, &local_list);
1222
1223 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1224 &local_list);
1225 return pre_used;
1226 }
1227
1228 void
1229 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1230 size_t& pre_used,
1231 size_t& cleared_h,
1232 size_t& freed_regions,
1233 UncleanRegionList* list,
1234 bool par) {
1235 assert(!hr->continuesHumongous(), "should have filtered these out");
1236 size_t res = 0;
1237 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1238 !hr->is_young()) {
1239 if (G1PolicyVerbose > 0)
1240 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1241 " during cleanup", hr, hr->used());
1242 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1243 }
1244 }
1245
1246 // FIXME: both this and shrink could probably be more efficient by
1247 // doing one "VirtualSpace::expand_by" call rather than several.
1248 void G1CollectedHeap::expand(size_t expand_bytes) {
1249 size_t old_mem_size = _g1_storage.committed_size();
1250 // We expand by a minimum of 1K.
1251 expand_bytes = MAX2(expand_bytes, (size_t)K);
1252 size_t aligned_expand_bytes =
1253 ReservedSpace::page_align_size_up(expand_bytes);
1254 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1255 HeapRegion::GrainBytes);
1256 expand_bytes = aligned_expand_bytes;
1257 while (expand_bytes > 0) {
1258 HeapWord* base = (HeapWord*)_g1_storage.high();
1259 // Commit more storage.
1260 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1261 if (!successful) {
1262 expand_bytes = 0;
1263 } else {
1264 expand_bytes -= HeapRegion::GrainBytes;
1265 // Expand the committed region.
1266 HeapWord* high = (HeapWord*) _g1_storage.high();
1267 _g1_committed.set_end(high);
1268 // Create a new HeapRegion.
1269 MemRegion mr(base, high);
1270 bool is_zeroed = !_g1_max_committed.contains(base);
1271 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1272
1273 // Now update max_committed if necessary.
1274 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1275
1276 // Add it to the HeapRegionSeq.
1277 _hrs->insert(hr);
1278 // Set the zero-fill state, according to whether it's already
1279 // zeroed.
1280 {
1281 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1282 if (is_zeroed) {
1283 hr->set_zero_fill_complete();
1284 put_free_region_on_list_locked(hr);
1285 } else {
1286 hr->set_zero_fill_needed();
1287 put_region_on_unclean_list_locked(hr);
1288 }
1289 }
1290 _free_regions++;
1291 // And we used up an expansion region to create it.
1292 _expansion_regions--;
1293 // Tell the cardtable about it.
1294 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1295 // And the offset table as well.
1296 _bot_shared->resize(_g1_committed.word_size());
1297 }
1298 }
1299 if (Verbose && PrintGC) {
1300 size_t new_mem_size = _g1_storage.committed_size();
1301 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1302 old_mem_size/K, aligned_expand_bytes/K,
1303 new_mem_size/K);
1304 }
1305 }
1306
1307 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1308 {
1309 size_t old_mem_size = _g1_storage.committed_size();
1310 size_t aligned_shrink_bytes =
1311 ReservedSpace::page_align_size_down(shrink_bytes);
1312 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1313 HeapRegion::GrainBytes);
1314 size_t num_regions_deleted = 0;
1315 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1316
1317 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1318 if (mr.byte_size() > 0)
1319 _g1_storage.shrink_by(mr.byte_size());
1320 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1321
1322 _g1_committed.set_end(mr.start());
1323 _free_regions -= num_regions_deleted;
1324 _expansion_regions += num_regions_deleted;
1325
1326 // Tell the cardtable about it.
1327 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1328
1329 // And the offset table as well.
1330 _bot_shared->resize(_g1_committed.word_size());
1331
1332 HeapRegionRemSet::shrink_heap(n_regions());
1333
1334 if (Verbose && PrintGC) {
1335 size_t new_mem_size = _g1_storage.committed_size();
1336 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1337 old_mem_size/K, aligned_shrink_bytes/K,
1338 new_mem_size/K);
1339 }
1340 }
1341
1342 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1343 release_gc_alloc_regions(true /* totally */);
1344 tear_down_region_lists(); // We will rebuild them in a moment.
1345 shrink_helper(shrink_bytes);
1346 rebuild_region_lists();
1347 }
1348
1349 // Public methods.
1350
1351 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1352 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1353 #endif // _MSC_VER
1354
1355
1356 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1357 SharedHeap(policy_),
1358 _g1_policy(policy_),
1359 _dirty_card_queue_set(false),
1360 _into_cset_dirty_card_queue_set(false),
1361 _ref_processor(NULL),
1362 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1363 _bot_shared(NULL),
1364 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1365 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1366 _evac_failure_scan_stack(NULL) ,
1367 _mark_in_progress(false),
1368 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1369 _cur_alloc_region(NULL),
1370 _refine_cte_cl(NULL),
1371 _free_region_list(NULL), _free_region_list_size(0),
1372 _free_regions(0),
1373 _full_collection(false),
1374 _unclean_region_list(),
1375 _unclean_regions_coming(false),
1376 _young_list(new YoungList(this)),
1377 _gc_time_stamp(0),
1378 _surviving_young_words(NULL),
1379 _full_collections_completed(0),
1380 _in_cset_fast_test(NULL),
1381 _in_cset_fast_test_base(NULL),
1382 _dirty_cards_region_list(NULL) {
1383 _g1h = this; // To catch bugs.
1384 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1385 vm_exit_during_initialization("Failed necessary allocation.");
1386 }
1387
1388 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1389
1390 int n_queues = MAX2((int)ParallelGCThreads, 1);
1391 _task_queues = new RefToScanQueueSet(n_queues);
1392
1393 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1394 assert(n_rem_sets > 0, "Invariant.");
1395
1396 HeapRegionRemSetIterator** iter_arr =
1397 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1398 for (int i = 0; i < n_queues; i++) {
1399 iter_arr[i] = new HeapRegionRemSetIterator();
1400 }
1401 _rem_set_iterator = iter_arr;
1402
1403 for (int i = 0; i < n_queues; i++) {
1404 RefToScanQueue* q = new RefToScanQueue();
1405 q->initialize();
1406 _task_queues->register_queue(i, q);
1407 }
1408
1409 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1410 _gc_alloc_regions[ap] = NULL;
1411 _gc_alloc_region_counts[ap] = 0;
1412 _retained_gc_alloc_regions[ap] = NULL;
1413 // by default, we do not retain a GC alloc region for each ap;
1414 // we'll override this, when appropriate, below
1415 _retain_gc_alloc_region[ap] = false;
1416 }
1417
1418 // We will try to remember the last half-full tenured region we
1419 // allocated to at the end of a collection so that we can re-use it
1420 // during the next collection.
1421 _retain_gc_alloc_region[GCAllocForTenured] = true;
1422
1423 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1424 }
1425
1426 jint G1CollectedHeap::initialize() {
1427 CollectedHeap::pre_initialize();
1428 os::enable_vtime();
1429
1430 // Necessary to satisfy locking discipline assertions.
1431
1432 MutexLocker x(Heap_lock);
1433
1434 // While there are no constraints in the GC code that HeapWordSize
1435 // be any particular value, there are multiple other areas in the
1436 // system which believe this to be true (e.g. oop->object_size in some
1437 // cases incorrectly returns the size in wordSize units rather than
1438 // HeapWordSize).
1439 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1440
1441 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1442 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1443
1444 // Ensure that the sizes are properly aligned.
1445 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1446 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1447
1448 _cg1r = new ConcurrentG1Refine();
1449
1450 // Reserve the maximum.
1451 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1452 // Includes the perm-gen.
1453
1454 const size_t total_reserved = max_byte_size + pgs->max_size();
1455 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1456
1457 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1458 HeapRegion::GrainBytes,
1459 false /*ism*/, addr);
1460
1461 if (UseCompressedOops) {
1462 if (addr != NULL && !heap_rs.is_reserved()) {
1463 // Failed to reserve at specified address - the requested memory
1464 // region is taken already, for example, by 'java' launcher.
1465 // Try again to reserver heap higher.
1466 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1467 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1468 false /*ism*/, addr);
1469 if (addr != NULL && !heap_rs0.is_reserved()) {
1470 // Failed to reserve at specified address again - give up.
1471 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1472 assert(addr == NULL, "");
1473 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1474 false /*ism*/, addr);
1475 heap_rs = heap_rs1;
1476 } else {
1477 heap_rs = heap_rs0;
1478 }
1479 }
1480 }
1481
1482 if (!heap_rs.is_reserved()) {
1483 vm_exit_during_initialization("Could not reserve enough space for object heap");
1484 return JNI_ENOMEM;
1485 }
1486
1487 // It is important to do this in a way such that concurrent readers can't
1488 // temporarily think somethings in the heap. (I've actually seen this
1489 // happen in asserts: DLD.)
1490 _reserved.set_word_size(0);
1491 _reserved.set_start((HeapWord*)heap_rs.base());
1492 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1493
1494 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1495
1496 _num_humongous_regions = 0;
1497
1498 // Create the gen rem set (and barrier set) for the entire reserved region.
1499 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1500 set_barrier_set(rem_set()->bs());
1501 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1502 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1503 } else {
1504 vm_exit_during_initialization("G1 requires a mod ref bs.");
1505 return JNI_ENOMEM;
1506 }
1507
1508 // Also create a G1 rem set.
1509 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1510 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1511 } else {
1512 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1513 return JNI_ENOMEM;
1514 }
1515
1516 // Carve out the G1 part of the heap.
1517
1518 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1519 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1520 g1_rs.size()/HeapWordSize);
1521 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1522
1523 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1524
1525 _g1_storage.initialize(g1_rs, 0);
1526 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1527 _g1_max_committed = _g1_committed;
1528 _hrs = new HeapRegionSeq(_expansion_regions);
1529 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1530 guarantee(_cur_alloc_region == NULL, "from constructor");
1531
1532 // 6843694 - ensure that the maximum region index can fit
1533 // in the remembered set structures.
1534 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1535 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1536
1537 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1538 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1539 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1540 "too many cards per region");
1541
1542 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1543 heap_word_size(init_byte_size));
1544
1545 _g1h = this;
1546
1547 _in_cset_fast_test_length = max_regions();
1548 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1549
1550 // We're biasing _in_cset_fast_test to avoid subtracting the
1551 // beginning of the heap every time we want to index; basically
1552 // it's the same with what we do with the card table.
1553 _in_cset_fast_test = _in_cset_fast_test_base -
1554 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1555
1556 // Clear the _cset_fast_test bitmap in anticipation of adding
1557 // regions to the incremental collection set for the first
1558 // evacuation pause.
1559 clear_cset_fast_test();
1560
1561 // Create the ConcurrentMark data structure and thread.
1562 // (Must do this late, so that "max_regions" is defined.)
1563 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1564 _cmThread = _cm->cmThread();
1565
1566 // ...and the concurrent zero-fill thread, if necessary.
1567 if (G1ConcZeroFill) {
1568 _czft = new ConcurrentZFThread();
1569 }
1570
1571 // Initialize the from_card cache structure of HeapRegionRemSet.
1572 HeapRegionRemSet::init_heap(max_regions());
1573
1574 // Now expand into the initial heap size.
1575 expand(init_byte_size);
1576
1577 // Perform any initialization actions delegated to the policy.
1578 g1_policy()->init();
1579
1580 g1_policy()->note_start_of_mark_thread();
1581
1582 _refine_cte_cl =
1583 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1584 g1_rem_set(),
1585 concurrent_g1_refine());
1586 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1587
1588 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1589 SATB_Q_FL_lock,
1590 G1SATBProcessCompletedThreshold,
1591 Shared_SATB_Q_lock);
1592
1593 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1594 DirtyCardQ_FL_lock,
1595 concurrent_g1_refine()->yellow_zone(),
1596 concurrent_g1_refine()->red_zone(),
1597 Shared_DirtyCardQ_lock);
1598
1599 if (G1DeferredRSUpdate) {
1600 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1601 DirtyCardQ_FL_lock,
1602 -1, // never trigger processing
1603 -1, // no limit on length
1604 Shared_DirtyCardQ_lock,
1605 &JavaThread::dirty_card_queue_set());
1606 }
1607
1608 // Initialize the card queue set used to hold cards containing
1609 // references into the collection set.
1610 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
1611 DirtyCardQ_FL_lock,
1612 -1, // never trigger processing
1613 -1, // no limit on length
1614 Shared_DirtyCardQ_lock,
1615 &JavaThread::dirty_card_queue_set());
1616
1617 // In case we're keeping closure specialization stats, initialize those
1618 // counts and that mechanism.
1619 SpecializationStats::clear();
1620
1621 _gc_alloc_region_list = NULL;
1622
1623 // Do later initialization work for concurrent refinement.
1624 _cg1r->init();
1625
1626 return JNI_OK;
1627 }
1628
1629 void G1CollectedHeap::ref_processing_init() {
1630 SharedHeap::ref_processing_init();
1631 MemRegion mr = reserved_region();
1632 _ref_processor = ReferenceProcessor::create_ref_processor(
1633 mr, // span
1634 false, // Reference discovery is not atomic
1635 // (though it shouldn't matter here.)
1636 true, // mt_discovery
1637 NULL, // is alive closure: need to fill this in for efficiency
1638 ParallelGCThreads,
1639 ParallelRefProcEnabled,
1640 true); // Setting next fields of discovered
1641 // lists requires a barrier.
1642 }
1643
1644 size_t G1CollectedHeap::capacity() const {
1645 return _g1_committed.byte_size();
1646 }
1647
1648 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
1649 DirtyCardQueue* into_cset_dcq,
1650 bool concurrent,
1651 int worker_i) {
1652 // Clean cards in the hot card cache
1653 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
1654
1655 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1656 int n_completed_buffers = 0;
1657 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
1658 n_completed_buffers++;
1659 }
1660 g1_policy()->record_update_rs_processed_buffers(worker_i,
1661 (double) n_completed_buffers);
1662 dcqs.clear_n_completed_buffers();
1663 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1664 }
1665
1666
1667 // Computes the sum of the storage used by the various regions.
1668
1669 size_t G1CollectedHeap::used() const {
1670 assert(Heap_lock->owner() != NULL,
1671 "Should be owned on this thread's behalf.");
1672 size_t result = _summary_bytes_used;
1673 // Read only once in case it is set to NULL concurrently
1674 HeapRegion* hr = _cur_alloc_region;
1675 if (hr != NULL)
1676 result += hr->used();
1677 return result;
1678 }
1679
1680 size_t G1CollectedHeap::used_unlocked() const {
1681 size_t result = _summary_bytes_used;
1682 return result;
1683 }
1684
1685 class SumUsedClosure: public HeapRegionClosure {
1686 size_t _used;
1687 public:
1688 SumUsedClosure() : _used(0) {}
1689 bool doHeapRegion(HeapRegion* r) {
1690 if (!r->continuesHumongous()) {
1691 _used += r->used();
1692 }
1693 return false;
1694 }
1695 size_t result() { return _used; }
1696 };
1697
1698 size_t G1CollectedHeap::recalculate_used() const {
1699 SumUsedClosure blk;
1700 _hrs->iterate(&blk);
1701 return blk.result();
1702 }
1703
1704 #ifndef PRODUCT
1705 class SumUsedRegionsClosure: public HeapRegionClosure {
1706 size_t _num;
1707 public:
1708 SumUsedRegionsClosure() : _num(0) {}
1709 bool doHeapRegion(HeapRegion* r) {
1710 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1711 _num += 1;
1712 }
1713 return false;
1714 }
1715 size_t result() { return _num; }
1716 };
1717
1718 size_t G1CollectedHeap::recalculate_used_regions() const {
1719 SumUsedRegionsClosure blk;
1720 _hrs->iterate(&blk);
1721 return blk.result();
1722 }
1723 #endif // PRODUCT
1724
1725 size_t G1CollectedHeap::unsafe_max_alloc() {
1726 if (_free_regions > 0) return HeapRegion::GrainBytes;
1727 // otherwise, is there space in the current allocation region?
1728
1729 // We need to store the current allocation region in a local variable
1730 // here. The problem is that this method doesn't take any locks and
1731 // there may be other threads which overwrite the current allocation
1732 // region field. attempt_allocation(), for example, sets it to NULL
1733 // and this can happen *after* the NULL check here but before the call
1734 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1735 // to be a problem in the optimized build, since the two loads of the
1736 // current allocation region field are optimized away.
1737 HeapRegion* car = _cur_alloc_region;
1738
1739 // FIXME: should iterate over all regions?
1740 if (car == NULL) {
1741 return 0;
1742 }
1743 return car->free();
1744 }
1745
1746 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1747 return
1748 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
1749 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
1750 }
1751
1752 void G1CollectedHeap::increment_full_collections_completed(bool outer) {
1753 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1754
1755 // We have already incremented _total_full_collections at the start
1756 // of the GC, so total_full_collections() represents how many full
1757 // collections have been started.
1758 unsigned int full_collections_started = total_full_collections();
1759
1760 // Given that this method is called at the end of a Full GC or of a
1761 // concurrent cycle, and those can be nested (i.e., a Full GC can
1762 // interrupt a concurrent cycle), the number of full collections
1763 // completed should be either one (in the case where there was no
1764 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1765 // behind the number of full collections started.
1766
1767 // This is the case for the inner caller, i.e. a Full GC.
1768 assert(outer ||
1769 (full_collections_started == _full_collections_completed + 1) ||
1770 (full_collections_started == _full_collections_completed + 2),
1771 err_msg("for inner caller: full_collections_started = %u "
1772 "is inconsistent with _full_collections_completed = %u",
1773 full_collections_started, _full_collections_completed));
1774
1775 // This is the case for the outer caller, i.e. the concurrent cycle.
1776 assert(!outer ||
1777 (full_collections_started == _full_collections_completed + 1),
1778 err_msg("for outer caller: full_collections_started = %u "
1779 "is inconsistent with _full_collections_completed = %u",
1780 full_collections_started, _full_collections_completed));
1781
1782 _full_collections_completed += 1;
1783
1784 // We need to clear the "in_progress" flag in the CM thread before
1785 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1786 // is set) so that if a waiter requests another System.gc() it doesn't
1787 // incorrectly see that a marking cyle is still in progress.
1788 if (outer) {
1789 _cmThread->clear_in_progress();
1790 }
1791
1792 // This notify_all() will ensure that a thread that called
1793 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1794 // and it's waiting for a full GC to finish will be woken up. It is
1795 // waiting in VM_G1IncCollectionPause::doit_epilogue().
1796 FullGCCount_lock->notify_all();
1797 }
1798
1799 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1800 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1801 assert(Heap_lock->is_locked(), "Precondition#2");
1802 GCCauseSetter gcs(this, cause);
1803 switch (cause) {
1804 case GCCause::_heap_inspection:
1805 case GCCause::_heap_dump: {
1806 HandleMark hm;
1807 do_full_collection(false); // don't clear all soft refs
1808 break;
1809 }
1810 default: // XXX FIX ME
1811 ShouldNotReachHere(); // Unexpected use of this function
1812 }
1813 }
1814
1815 void G1CollectedHeap::collect(GCCause::Cause cause) {
1816 // The caller doesn't have the Heap_lock
1817 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1818
1819 unsigned int gc_count_before;
1820 unsigned int full_gc_count_before;
1821 {
1822 MutexLocker ml(Heap_lock);
1823 // Read the GC count while holding the Heap_lock
1824 gc_count_before = SharedHeap::heap()->total_collections();
1825 full_gc_count_before = SharedHeap::heap()->total_full_collections();
1826
1827 // Don't want to do a GC until cleanup is completed.
1828 wait_for_cleanup_complete();
1829
1830 // We give up heap lock; VMThread::execute gets it back below
1831 }
1832
1833 if (should_do_concurrent_full_gc(cause)) {
1834 // Schedule an initial-mark evacuation pause that will start a
1835 // concurrent cycle.
1836 VM_G1IncCollectionPause op(gc_count_before,
1837 true, /* should_initiate_conc_mark */
1838 g1_policy()->max_pause_time_ms(),
1839 cause);
1840 VMThread::execute(&op);
1841 } else {
1842 if (cause == GCCause::_gc_locker
1843 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1844
1845 // Schedule a standard evacuation pause.
1846 VM_G1IncCollectionPause op(gc_count_before,
1847 false, /* should_initiate_conc_mark */
1848 g1_policy()->max_pause_time_ms(),
1849 cause);
1850 VMThread::execute(&op);
1851 } else {
1852 // Schedule a Full GC.
1853 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
1854 VMThread::execute(&op);
1855 }
1856 }
1857 }
1858
1859 bool G1CollectedHeap::is_in(const void* p) const {
1860 if (_g1_committed.contains(p)) {
1861 HeapRegion* hr = _hrs->addr_to_region(p);
1862 return hr->is_in(p);
1863 } else {
1864 return _perm_gen->as_gen()->is_in(p);
1865 }
1866 }
1867
1868 // Iteration functions.
1869
1870 // Iterates an OopClosure over all ref-containing fields of objects
1871 // within a HeapRegion.
1872
1873 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1874 MemRegion _mr;
1875 OopClosure* _cl;
1876 public:
1877 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1878 : _mr(mr), _cl(cl) {}
1879 bool doHeapRegion(HeapRegion* r) {
1880 if (! r->continuesHumongous()) {
1881 r->oop_iterate(_cl);
1882 }
1883 return false;
1884 }
1885 };
1886
1887 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1888 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1889 _hrs->iterate(&blk);
1890 if (do_perm) {
1891 perm_gen()->oop_iterate(cl);
1892 }
1893 }
1894
1895 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1896 IterateOopClosureRegionClosure blk(mr, cl);
1897 _hrs->iterate(&blk);
1898 if (do_perm) {
1899 perm_gen()->oop_iterate(cl);
1900 }
1901 }
1902
1903 // Iterates an ObjectClosure over all objects within a HeapRegion.
1904
1905 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1906 ObjectClosure* _cl;
1907 public:
1908 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1909 bool doHeapRegion(HeapRegion* r) {
1910 if (! r->continuesHumongous()) {
1911 r->object_iterate(_cl);
1912 }
1913 return false;
1914 }
1915 };
1916
1917 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1918 IterateObjectClosureRegionClosure blk(cl);
1919 _hrs->iterate(&blk);
1920 if (do_perm) {
1921 perm_gen()->object_iterate(cl);
1922 }
1923 }
1924
1925 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1926 // FIXME: is this right?
1927 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1928 }
1929
1930 // Calls a SpaceClosure on a HeapRegion.
1931
1932 class SpaceClosureRegionClosure: public HeapRegionClosure {
1933 SpaceClosure* _cl;
1934 public:
1935 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1936 bool doHeapRegion(HeapRegion* r) {
1937 _cl->do_space(r);
1938 return false;
1939 }
1940 };
1941
1942 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1943 SpaceClosureRegionClosure blk(cl);
1944 _hrs->iterate(&blk);
1945 }
1946
1947 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1948 _hrs->iterate(cl);
1949 }
1950
1951 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1952 HeapRegionClosure* cl) {
1953 _hrs->iterate_from(r, cl);
1954 }
1955
1956 void
1957 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1958 _hrs->iterate_from(idx, cl);
1959 }
1960
1961 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1962
1963 void
1964 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1965 int worker,
1966 jint claim_value) {
1967 const size_t regions = n_regions();
1968 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
1969 // try to spread out the starting points of the workers
1970 const size_t start_index = regions / worker_num * (size_t) worker;
1971
1972 // each worker will actually look at all regions
1973 for (size_t count = 0; count < regions; ++count) {
1974 const size_t index = (start_index + count) % regions;
1975 assert(0 <= index && index < regions, "sanity");
1976 HeapRegion* r = region_at(index);
1977 // we'll ignore "continues humongous" regions (we'll process them
1978 // when we come across their corresponding "start humongous"
1979 // region) and regions already claimed
1980 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1981 continue;
1982 }
1983 // OK, try to claim it
1984 if (r->claimHeapRegion(claim_value)) {
1985 // success!
1986 assert(!r->continuesHumongous(), "sanity");
1987 if (r->startsHumongous()) {
1988 // If the region is "starts humongous" we'll iterate over its
1989 // "continues humongous" first; in fact we'll do them
1990 // first. The order is important. In on case, calling the
1991 // closure on the "starts humongous" region might de-allocate
1992 // and clear all its "continues humongous" regions and, as a
1993 // result, we might end up processing them twice. So, we'll do
1994 // them first (notice: most closures will ignore them anyway) and
1995 // then we'll do the "starts humongous" region.
1996 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1997 HeapRegion* chr = region_at(ch_index);
1998
1999 // if the region has already been claimed or it's not
2000 // "continues humongous" we're done
2001 if (chr->claim_value() == claim_value ||
2002 !chr->continuesHumongous()) {
2003 break;
2004 }
2005
2006 // Noone should have claimed it directly. We can given
2007 // that we claimed its "starts humongous" region.
2008 assert(chr->claim_value() != claim_value, "sanity");
2009 assert(chr->humongous_start_region() == r, "sanity");
2010
2011 if (chr->claimHeapRegion(claim_value)) {
2012 // we should always be able to claim it; noone else should
2013 // be trying to claim this region
2014
2015 bool res2 = cl->doHeapRegion(chr);
2016 assert(!res2, "Should not abort");
2017
2018 // Right now, this holds (i.e., no closure that actually
2019 // does something with "continues humongous" regions
2020 // clears them). We might have to weaken it in the future,
2021 // but let's leave these two asserts here for extra safety.
2022 assert(chr->continuesHumongous(), "should still be the case");
2023 assert(chr->humongous_start_region() == r, "sanity");
2024 } else {
2025 guarantee(false, "we should not reach here");
2026 }
2027 }
2028 }
2029
2030 assert(!r->continuesHumongous(), "sanity");
2031 bool res = cl->doHeapRegion(r);
2032 assert(!res, "Should not abort");
2033 }
2034 }
2035 }
2036
2037 class ResetClaimValuesClosure: public HeapRegionClosure {
2038 public:
2039 bool doHeapRegion(HeapRegion* r) {
2040 r->set_claim_value(HeapRegion::InitialClaimValue);
2041 return false;
2042 }
2043 };
2044
2045 void
2046 G1CollectedHeap::reset_heap_region_claim_values() {
2047 ResetClaimValuesClosure blk;
2048 heap_region_iterate(&blk);
2049 }
2050
2051 #ifdef ASSERT
2052 // This checks whether all regions in the heap have the correct claim
2053 // value. I also piggy-backed on this a check to ensure that the
2054 // humongous_start_region() information on "continues humongous"
2055 // regions is correct.
2056
2057 class CheckClaimValuesClosure : public HeapRegionClosure {
2058 private:
2059 jint _claim_value;
2060 size_t _failures;
2061 HeapRegion* _sh_region;
2062 public:
2063 CheckClaimValuesClosure(jint claim_value) :
2064 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2065 bool doHeapRegion(HeapRegion* r) {
2066 if (r->claim_value() != _claim_value) {
2067 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2068 "claim value = %d, should be %d",
2069 r->bottom(), r->end(), r->claim_value(),
2070 _claim_value);
2071 ++_failures;
2072 }
2073 if (!r->isHumongous()) {
2074 _sh_region = NULL;
2075 } else if (r->startsHumongous()) {
2076 _sh_region = r;
2077 } else if (r->continuesHumongous()) {
2078 if (r->humongous_start_region() != _sh_region) {
2079 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2080 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2081 r->bottom(), r->end(),
2082 r->humongous_start_region(),
2083 _sh_region);
2084 ++_failures;
2085 }
2086 }
2087 return false;
2088 }
2089 size_t failures() {
2090 return _failures;
2091 }
2092 };
2093
2094 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2095 CheckClaimValuesClosure cl(claim_value);
2096 heap_region_iterate(&cl);
2097 return cl.failures() == 0;
2098 }
2099 #endif // ASSERT
2100
2101 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2102 HeapRegion* r = g1_policy()->collection_set();
2103 while (r != NULL) {
2104 HeapRegion* next = r->next_in_collection_set();
2105 if (cl->doHeapRegion(r)) {
2106 cl->incomplete();
2107 return;
2108 }
2109 r = next;
2110 }
2111 }
2112
2113 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2114 HeapRegionClosure *cl) {
2115 if (r == NULL) {
2116 // The CSet is empty so there's nothing to do.
2117 return;
2118 }
2119
2120 assert(r->in_collection_set(),
2121 "Start region must be a member of the collection set.");
2122 HeapRegion* cur = r;
2123 while (cur != NULL) {
2124 HeapRegion* next = cur->next_in_collection_set();
2125 if (cl->doHeapRegion(cur) && false) {
2126 cl->incomplete();
2127 return;
2128 }
2129 cur = next;
2130 }
2131 cur = g1_policy()->collection_set();
2132 while (cur != r) {
2133 HeapRegion* next = cur->next_in_collection_set();
2134 if (cl->doHeapRegion(cur) && false) {
2135 cl->incomplete();
2136 return;
2137 }
2138 cur = next;
2139 }
2140 }
2141
2142 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2143 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2144 }
2145
2146
2147 Space* G1CollectedHeap::space_containing(const void* addr) const {
2148 Space* res = heap_region_containing(addr);
2149 if (res == NULL)
2150 res = perm_gen()->space_containing(addr);
2151 return res;
2152 }
2153
2154 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2155 Space* sp = space_containing(addr);
2156 if (sp != NULL) {
2157 return sp->block_start(addr);
2158 }
2159 return NULL;
2160 }
2161
2162 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2163 Space* sp = space_containing(addr);
2164 assert(sp != NULL, "block_size of address outside of heap");
2165 return sp->block_size(addr);
2166 }
2167
2168 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2169 Space* sp = space_containing(addr);
2170 return sp->block_is_obj(addr);
2171 }
2172
2173 bool G1CollectedHeap::supports_tlab_allocation() const {
2174 return true;
2175 }
2176
2177 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2178 return HeapRegion::GrainBytes;
2179 }
2180
2181 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2182 // Return the remaining space in the cur alloc region, but not less than
2183 // the min TLAB size.
2184
2185 // Also, this value can be at most the humongous object threshold,
2186 // since we can't allow tlabs to grow big enough to accomodate
2187 // humongous objects.
2188
2189 // We need to store the cur alloc region locally, since it might change
2190 // between when we test for NULL and when we use it later.
2191 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2192 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2193
2194 if (cur_alloc_space == NULL) {
2195 return max_tlab_size;
2196 } else {
2197 return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize),
2198 max_tlab_size);
2199 }
2200 }
2201
2202 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
2203 assert(!isHumongous(word_size),
2204 err_msg("a TLAB should not be of humongous size, "
2205 "word_size = "SIZE_FORMAT, word_size));
2206 bool dummy;
2207 return G1CollectedHeap::mem_allocate(word_size, false, true, &dummy);
2208 }
2209
2210 bool G1CollectedHeap::allocs_are_zero_filled() {
2211 return false;
2212 }
2213
2214 size_t G1CollectedHeap::large_typearray_limit() {
2215 // FIXME
2216 return HeapRegion::GrainBytes/HeapWordSize;
2217 }
2218
2219 size_t G1CollectedHeap::max_capacity() const {
2220 return g1_reserved_obj_bytes();
2221 }
2222
2223 jlong G1CollectedHeap::millis_since_last_gc() {
2224 // assert(false, "NYI");
2225 return 0;
2226 }
2227
2228
2229 void G1CollectedHeap::prepare_for_verify() {
2230 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2231 ensure_parsability(false);
2232 }
2233 g1_rem_set()->prepare_for_verify();
2234 }
2235
2236 class VerifyLivenessOopClosure: public OopClosure {
2237 G1CollectedHeap* g1h;
2238 public:
2239 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2240 g1h = _g1h;
2241 }
2242 void do_oop(narrowOop *p) { do_oop_work(p); }
2243 void do_oop( oop *p) { do_oop_work(p); }
2244
2245 template <class T> void do_oop_work(T *p) {
2246 oop obj = oopDesc::load_decode_heap_oop(p);
2247 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2248 "Dead object referenced by a not dead object");
2249 }
2250 };
2251
2252 class VerifyObjsInRegionClosure: public ObjectClosure {
2253 private:
2254 G1CollectedHeap* _g1h;
2255 size_t _live_bytes;
2256 HeapRegion *_hr;
2257 bool _use_prev_marking;
2258 public:
2259 // use_prev_marking == true -> use "prev" marking information,
2260 // use_prev_marking == false -> use "next" marking information
2261 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2262 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2263 _g1h = G1CollectedHeap::heap();
2264 }
2265 void do_object(oop o) {
2266 VerifyLivenessOopClosure isLive(_g1h);
2267 assert(o != NULL, "Huh?");
2268 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2269 o->oop_iterate(&isLive);
2270 if (!_hr->obj_allocated_since_prev_marking(o)) {
2271 size_t obj_size = o->size(); // Make sure we don't overflow
2272 _live_bytes += (obj_size * HeapWordSize);
2273 }
2274 }
2275 }
2276 size_t live_bytes() { return _live_bytes; }
2277 };
2278
2279 class PrintObjsInRegionClosure : public ObjectClosure {
2280 HeapRegion *_hr;
2281 G1CollectedHeap *_g1;
2282 public:
2283 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2284 _g1 = G1CollectedHeap::heap();
2285 };
2286
2287 void do_object(oop o) {
2288 if (o != NULL) {
2289 HeapWord *start = (HeapWord *) o;
2290 size_t word_sz = o->size();
2291 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2292 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2293 (void*) o, word_sz,
2294 _g1->isMarkedPrev(o),
2295 _g1->isMarkedNext(o),
2296 _hr->obj_allocated_since_prev_marking(o));
2297 HeapWord *end = start + word_sz;
2298 HeapWord *cur;
2299 int *val;
2300 for (cur = start; cur < end; cur++) {
2301 val = (int *) cur;
2302 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2303 }
2304 }
2305 }
2306 };
2307
2308 class VerifyRegionClosure: public HeapRegionClosure {
2309 private:
2310 bool _allow_dirty;
2311 bool _par;
2312 bool _use_prev_marking;
2313 bool _failures;
2314 public:
2315 // use_prev_marking == true -> use "prev" marking information,
2316 // use_prev_marking == false -> use "next" marking information
2317 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2318 : _allow_dirty(allow_dirty),
2319 _par(par),
2320 _use_prev_marking(use_prev_marking),
2321 _failures(false) {}
2322
2323 bool failures() {
2324 return _failures;
2325 }
2326
2327 bool doHeapRegion(HeapRegion* r) {
2328 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2329 "Should be unclaimed at verify points.");
2330 if (!r->continuesHumongous()) {
2331 bool failures = false;
2332 r->verify(_allow_dirty, _use_prev_marking, &failures);
2333 if (failures) {
2334 _failures = true;
2335 } else {
2336 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2337 r->object_iterate(¬_dead_yet_cl);
2338 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2339 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2340 "max_live_bytes "SIZE_FORMAT" "
2341 "< calculated "SIZE_FORMAT,
2342 r->bottom(), r->end(),
2343 r->max_live_bytes(),
2344 not_dead_yet_cl.live_bytes());
2345 _failures = true;
2346 }
2347 }
2348 }
2349 return false; // stop the region iteration if we hit a failure
2350 }
2351 };
2352
2353 class VerifyRootsClosure: public OopsInGenClosure {
2354 private:
2355 G1CollectedHeap* _g1h;
2356 bool _use_prev_marking;
2357 bool _failures;
2358 public:
2359 // use_prev_marking == true -> use "prev" marking information,
2360 // use_prev_marking == false -> use "next" marking information
2361 VerifyRootsClosure(bool use_prev_marking) :
2362 _g1h(G1CollectedHeap::heap()),
2363 _use_prev_marking(use_prev_marking),
2364 _failures(false) { }
2365
2366 bool failures() { return _failures; }
2367
2368 template <class T> void do_oop_nv(T* p) {
2369 T heap_oop = oopDesc::load_heap_oop(p);
2370 if (!oopDesc::is_null(heap_oop)) {
2371 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2372 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2373 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2374 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2375 obj->print_on(gclog_or_tty);
2376 _failures = true;
2377 }
2378 }
2379 }
2380
2381 void do_oop(oop* p) { do_oop_nv(p); }
2382 void do_oop(narrowOop* p) { do_oop_nv(p); }
2383 };
2384
2385 // This is the task used for parallel heap verification.
2386
2387 class G1ParVerifyTask: public AbstractGangTask {
2388 private:
2389 G1CollectedHeap* _g1h;
2390 bool _allow_dirty;
2391 bool _use_prev_marking;
2392 bool _failures;
2393
2394 public:
2395 // use_prev_marking == true -> use "prev" marking information,
2396 // use_prev_marking == false -> use "next" marking information
2397 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2398 bool use_prev_marking) :
2399 AbstractGangTask("Parallel verify task"),
2400 _g1h(g1h),
2401 _allow_dirty(allow_dirty),
2402 _use_prev_marking(use_prev_marking),
2403 _failures(false) { }
2404
2405 bool failures() {
2406 return _failures;
2407 }
2408
2409 void work(int worker_i) {
2410 HandleMark hm;
2411 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2412 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2413 HeapRegion::ParVerifyClaimValue);
2414 if (blk.failures()) {
2415 _failures = true;
2416 }
2417 }
2418 };
2419
2420 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2421 verify(allow_dirty, silent, /* use_prev_marking */ true);
2422 }
2423
2424 void G1CollectedHeap::verify(bool allow_dirty,
2425 bool silent,
2426 bool use_prev_marking) {
2427 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2428 if (!silent) { gclog_or_tty->print("roots "); }
2429 VerifyRootsClosure rootsCl(use_prev_marking);
2430 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2431 process_strong_roots(true, // activate StrongRootsScope
2432 false,
2433 SharedHeap::SO_AllClasses,
2434 &rootsCl,
2435 &blobsCl,
2436 &rootsCl);
2437 bool failures = rootsCl.failures();
2438 rem_set()->invalidate(perm_gen()->used_region(), false);
2439 if (!silent) { gclog_or_tty->print("heapRegions "); }
2440 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2441 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2442 "sanity check");
2443
2444 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2445 int n_workers = workers()->total_workers();
2446 set_par_threads(n_workers);
2447 workers()->run_task(&task);
2448 set_par_threads(0);
2449 if (task.failures()) {
2450 failures = true;
2451 }
2452
2453 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2454 "sanity check");
2455
2456 reset_heap_region_claim_values();
2457
2458 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2459 "sanity check");
2460 } else {
2461 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2462 _hrs->iterate(&blk);
2463 if (blk.failures()) {
2464 failures = true;
2465 }
2466 }
2467 if (!silent) gclog_or_tty->print("remset ");
2468 rem_set()->verify();
2469
2470 if (failures) {
2471 gclog_or_tty->print_cr("Heap:");
2472 print_on(gclog_or_tty, true /* extended */);
2473 gclog_or_tty->print_cr("");
2474 #ifndef PRODUCT
2475 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2476 concurrent_mark()->print_reachable("at-verification-failure",
2477 use_prev_marking, false /* all */);
2478 }
2479 #endif
2480 gclog_or_tty->flush();
2481 }
2482 guarantee(!failures, "there should not have been any failures");
2483 } else {
2484 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2485 }
2486 }
2487
2488 class PrintRegionClosure: public HeapRegionClosure {
2489 outputStream* _st;
2490 public:
2491 PrintRegionClosure(outputStream* st) : _st(st) {}
2492 bool doHeapRegion(HeapRegion* r) {
2493 r->print_on(_st);
2494 return false;
2495 }
2496 };
2497
2498 void G1CollectedHeap::print() const { print_on(tty); }
2499
2500 void G1CollectedHeap::print_on(outputStream* st) const {
2501 print_on(st, PrintHeapAtGCExtended);
2502 }
2503
2504 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2505 st->print(" %-20s", "garbage-first heap");
2506 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2507 capacity()/K, used_unlocked()/K);
2508 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2509 _g1_storage.low_boundary(),
2510 _g1_storage.high(),
2511 _g1_storage.high_boundary());
2512 st->cr();
2513 st->print(" region size " SIZE_FORMAT "K, ",
2514 HeapRegion::GrainBytes/K);
2515 size_t young_regions = _young_list->length();
2516 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2517 young_regions, young_regions * HeapRegion::GrainBytes / K);
2518 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2519 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2520 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2521 st->cr();
2522 perm()->as_gen()->print_on(st);
2523 if (extended) {
2524 st->cr();
2525 print_on_extended(st);
2526 }
2527 }
2528
2529 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2530 PrintRegionClosure blk(st);
2531 _hrs->iterate(&blk);
2532 }
2533
2534 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2535 if (G1CollectedHeap::use_parallel_gc_threads()) {
2536 workers()->print_worker_threads_on(st);
2537 }
2538
2539 _cmThread->print_on(st);
2540 st->cr();
2541
2542 _cm->print_worker_threads_on(st);
2543
2544 _cg1r->print_worker_threads_on(st);
2545
2546 _czft->print_on(st);
2547 st->cr();
2548 }
2549
2550 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2551 if (G1CollectedHeap::use_parallel_gc_threads()) {
2552 workers()->threads_do(tc);
2553 }
2554 tc->do_thread(_cmThread);
2555 _cg1r->threads_do(tc);
2556 tc->do_thread(_czft);
2557 }
2558
2559 void G1CollectedHeap::print_tracing_info() const {
2560 // We'll overload this to mean "trace GC pause statistics."
2561 if (TraceGen0Time || TraceGen1Time) {
2562 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2563 // to that.
2564 g1_policy()->print_tracing_info();
2565 }
2566 if (G1SummarizeRSetStats) {
2567 g1_rem_set()->print_summary_info();
2568 }
2569 if (G1SummarizeConcMark) {
2570 concurrent_mark()->print_summary_info();
2571 }
2572 if (G1SummarizeZFStats) {
2573 ConcurrentZFThread::print_summary_info();
2574 }
2575 g1_policy()->print_yg_surv_rate_info();
2576
2577 SpecializationStats::print();
2578 }
2579
2580
2581 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2582 HeapRegion* hr = heap_region_containing(addr);
2583 if (hr == NULL) {
2584 return 0;
2585 } else {
2586 return 1;
2587 }
2588 }
2589
2590 G1CollectedHeap* G1CollectedHeap::heap() {
2591 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2592 "not a garbage-first heap");
2593 return _g1h;
2594 }
2595
2596 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2597 // always_do_update_barrier = false;
2598 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2599 // Call allocation profiler
2600 AllocationProfiler::iterate_since_last_gc();
2601 // Fill TLAB's and such
2602 ensure_parsability(true);
2603 }
2604
2605 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2606 // FIXME: what is this about?
2607 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2608 // is set.
2609 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2610 "derived pointer present"));
2611 // always_do_update_barrier = true;
2612 }
2613
2614 void G1CollectedHeap::do_collection_pause() {
2615 assert(Heap_lock->owned_by_self(), "we assume we'reholding the Heap_lock");
2616
2617 // Read the GC count while holding the Heap_lock
2618 // we need to do this _before_ wait_for_cleanup_complete(), to
2619 // ensure that we do not give up the heap lock and potentially
2620 // pick up the wrong count
2621 unsigned int gc_count_before = SharedHeap::heap()->total_collections();
2622
2623 // Don't want to do a GC pause while cleanup is being completed!
2624 wait_for_cleanup_complete();
2625
2626 g1_policy()->record_stop_world_start();
2627 {
2628 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2629 VM_G1IncCollectionPause op(gc_count_before,
2630 false, /* should_initiate_conc_mark */
2631 g1_policy()->max_pause_time_ms(),
2632 GCCause::_g1_inc_collection_pause);
2633 VMThread::execute(&op);
2634 }
2635 }
2636
2637 void
2638 G1CollectedHeap::doConcurrentMark() {
2639 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2640 if (!_cmThread->in_progress()) {
2641 _cmThread->set_started();
2642 CGC_lock->notify();
2643 }
2644 }
2645
2646 class VerifyMarkedObjsClosure: public ObjectClosure {
2647 G1CollectedHeap* _g1h;
2648 public:
2649 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2650 void do_object(oop obj) {
2651 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2652 "markandsweep mark should agree with concurrent deadness");
2653 }
2654 };
2655
2656 void
2657 G1CollectedHeap::checkConcurrentMark() {
2658 VerifyMarkedObjsClosure verifycl(this);
2659 // MutexLockerEx x(getMarkBitMapLock(),
2660 // Mutex::_no_safepoint_check_flag);
2661 object_iterate(&verifycl, false);
2662 }
2663
2664 void G1CollectedHeap::do_sync_mark() {
2665 _cm->checkpointRootsInitial();
2666 _cm->markFromRoots();
2667 _cm->checkpointRootsFinal(false);
2668 }
2669
2670 // <NEW PREDICTION>
2671
2672 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2673 bool young) {
2674 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2675 }
2676
2677 void G1CollectedHeap::check_if_region_is_too_expensive(double
2678 predicted_time_ms) {
2679 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2680 }
2681
2682 size_t G1CollectedHeap::pending_card_num() {
2683 size_t extra_cards = 0;
2684 JavaThread *curr = Threads::first();
2685 while (curr != NULL) {
2686 DirtyCardQueue& dcq = curr->dirty_card_queue();
2687 extra_cards += dcq.size();
2688 curr = curr->next();
2689 }
2690 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2691 size_t buffer_size = dcqs.buffer_size();
2692 size_t buffer_num = dcqs.completed_buffers_num();
2693 return buffer_size * buffer_num + extra_cards;
2694 }
2695
2696 size_t G1CollectedHeap::max_pending_card_num() {
2697 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2698 size_t buffer_size = dcqs.buffer_size();
2699 size_t buffer_num = dcqs.completed_buffers_num();
2700 int thread_num = Threads::number_of_threads();
2701 return (buffer_num + thread_num) * buffer_size;
2702 }
2703
2704 size_t G1CollectedHeap::cards_scanned() {
2705 return g1_rem_set()->cardsScanned();
2706 }
2707
2708 void
2709 G1CollectedHeap::setup_surviving_young_words() {
2710 guarantee( _surviving_young_words == NULL, "pre-condition" );
2711 size_t array_length = g1_policy()->young_cset_length();
2712 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2713 if (_surviving_young_words == NULL) {
2714 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2715 "Not enough space for young surv words summary.");
2716 }
2717 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2718 #ifdef ASSERT
2719 for (size_t i = 0; i < array_length; ++i) {
2720 assert( _surviving_young_words[i] == 0, "memset above" );
2721 }
2722 #endif // !ASSERT
2723 }
2724
2725 void
2726 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2727 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2728 size_t array_length = g1_policy()->young_cset_length();
2729 for (size_t i = 0; i < array_length; ++i)
2730 _surviving_young_words[i] += surv_young_words[i];
2731 }
2732
2733 void
2734 G1CollectedHeap::cleanup_surviving_young_words() {
2735 guarantee( _surviving_young_words != NULL, "pre-condition" );
2736 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2737 _surviving_young_words = NULL;
2738 }
2739
2740 // </NEW PREDICTION>
2741
2742 struct PrepareForRSScanningClosure : public HeapRegionClosure {
2743 bool doHeapRegion(HeapRegion *r) {
2744 r->rem_set()->set_iter_claimed(0);
2745 return false;
2746 }
2747 };
2748
2749 #if TASKQUEUE_STATS
2750 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2751 st->print_raw_cr("GC Task Stats");
2752 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2753 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2754 }
2755
2756 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
2757 print_taskqueue_stats_hdr(st);
2758
2759 TaskQueueStats totals;
2760 const int n = workers() != NULL ? workers()->total_workers() : 1;
2761 for (int i = 0; i < n; ++i) {
2762 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
2763 totals += task_queue(i)->stats;
2764 }
2765 st->print_raw("tot "); totals.print(st); st->cr();
2766
2767 DEBUG_ONLY(totals.verify());
2768 }
2769
2770 void G1CollectedHeap::reset_taskqueue_stats() {
2771 const int n = workers() != NULL ? workers()->total_workers() : 1;
2772 for (int i = 0; i < n; ++i) {
2773 task_queue(i)->stats.reset();
2774 }
2775 }
2776 #endif // TASKQUEUE_STATS
2777
2778 void
2779 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2780 if (GC_locker::check_active_before_gc()) {
2781 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2782 }
2783
2784 if (PrintHeapAtGC) {
2785 Universe::print_heap_before_gc();
2786 }
2787
2788 {
2789 ResourceMark rm;
2790
2791 // This call will decide whether this pause is an initial-mark
2792 // pause. If it is, during_initial_mark_pause() will return true
2793 // for the duration of this pause.
2794 g1_policy()->decide_on_conc_mark_initiation();
2795
2796 char verbose_str[128];
2797 sprintf(verbose_str, "GC pause ");
2798 if (g1_policy()->in_young_gc_mode()) {
2799 if (g1_policy()->full_young_gcs())
2800 strcat(verbose_str, "(young)");
2801 else
2802 strcat(verbose_str, "(partial)");
2803 }
2804 if (g1_policy()->during_initial_mark_pause()) {
2805 strcat(verbose_str, " (initial-mark)");
2806 // We are about to start a marking cycle, so we increment the
2807 // full collection counter.
2808 increment_total_full_collections();
2809 }
2810
2811 // if PrintGCDetails is on, we'll print long statistics information
2812 // in the collector policy code, so let's not print this as the output
2813 // is messy if we do.
2814 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2815 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2816 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2817
2818 TraceMemoryManagerStats tms(false /* fullGC */);
2819
2820 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2821 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2822 guarantee(!is_gc_active(), "collection is not reentrant");
2823 assert(regions_accounted_for(), "Region leakage!");
2824
2825 increment_gc_time_stamp();
2826
2827 if (g1_policy()->in_young_gc_mode()) {
2828 assert(check_young_list_well_formed(),
2829 "young list should be well formed");
2830 }
2831
2832 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2833 IsGCActiveMark x;
2834
2835 gc_prologue(false);
2836 increment_total_collections(false /* full gc */);
2837
2838 #if G1_REM_SET_LOGGING
2839 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2840 print();
2841 #endif
2842
2843 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2844 HandleMark hm; // Discard invalid handles created during verification
2845 prepare_for_verify();
2846 gclog_or_tty->print(" VerifyBeforeGC:");
2847 Universe::verify(false);
2848 }
2849
2850 COMPILER2_PRESENT(DerivedPointerTable::clear());
2851
2852 // We want to turn off ref discovery, if necessary, and turn it back on
2853 // on again later if we do. XXX Dubious: why is discovery disabled?
2854 bool was_enabled = ref_processor()->discovery_enabled();
2855 if (was_enabled) ref_processor()->disable_discovery();
2856
2857 // Forget the current alloc region (we might even choose it to be part
2858 // of the collection set!).
2859 abandon_cur_alloc_region();
2860
2861 // The elapsed time induced by the start time below deliberately elides
2862 // the possible verification above.
2863 double start_time_sec = os::elapsedTime();
2864 size_t start_used_bytes = used();
2865
2866 #if YOUNG_LIST_VERBOSE
2867 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
2868 _young_list->print();
2869 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
2870 #endif // YOUNG_LIST_VERBOSE
2871
2872 g1_policy()->record_collection_pause_start(start_time_sec,
2873 start_used_bytes);
2874
2875 #if YOUNG_LIST_VERBOSE
2876 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
2877 _young_list->print();
2878 #endif // YOUNG_LIST_VERBOSE
2879
2880 if (g1_policy()->during_initial_mark_pause()) {
2881 concurrent_mark()->checkpointRootsInitialPre();
2882 }
2883 save_marks();
2884
2885 // We must do this before any possible evacuation that should propagate
2886 // marks.
2887 if (mark_in_progress()) {
2888 double start_time_sec = os::elapsedTime();
2889
2890 _cm->drainAllSATBBuffers();
2891 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2892 g1_policy()->record_satb_drain_time(finish_mark_ms);
2893 }
2894 // Record the number of elements currently on the mark stack, so we
2895 // only iterate over these. (Since evacuation may add to the mark
2896 // stack, doing more exposes race conditions.) If no mark is in
2897 // progress, this will be zero.
2898 _cm->set_oops_do_bound();
2899
2900 assert(regions_accounted_for(), "Region leakage.");
2901
2902 if (mark_in_progress())
2903 concurrent_mark()->newCSet();
2904
2905 #if YOUNG_LIST_VERBOSE
2906 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
2907 _young_list->print();
2908 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
2909 #endif // YOUNG_LIST_VERBOSE
2910
2911 g1_policy()->choose_collection_set(target_pause_time_ms);
2912
2913 // Nothing to do if we were unable to choose a collection set.
2914 #if G1_REM_SET_LOGGING
2915 gclog_or_tty->print_cr("\nAfter pause, heap:");
2916 print();
2917 #endif
2918 PrepareForRSScanningClosure prepare_for_rs_scan;
2919 collection_set_iterate(&prepare_for_rs_scan);
2920
2921 setup_surviving_young_words();
2922
2923 // Set up the gc allocation regions.
2924 get_gc_alloc_regions();
2925
2926 // Actually do the work...
2927 evacuate_collection_set();
2928
2929 free_collection_set(g1_policy()->collection_set());
2930 g1_policy()->clear_collection_set();
2931
2932 cleanup_surviving_young_words();
2933
2934 // Start a new incremental collection set for the next pause.
2935 g1_policy()->start_incremental_cset_building();
2936
2937 // Clear the _cset_fast_test bitmap in anticipation of adding
2938 // regions to the incremental collection set for the next
2939 // evacuation pause.
2940 clear_cset_fast_test();
2941
2942 if (g1_policy()->in_young_gc_mode()) {
2943 _young_list->reset_sampled_info();
2944
2945 // Don't check the whole heap at this point as the
2946 // GC alloc regions from this pause have been tagged
2947 // as survivors and moved on to the survivor list.
2948 // Survivor regions will fail the !is_young() check.
2949 assert(check_young_list_empty(false /* check_heap */),
2950 "young list should be empty");
2951
2952 #if YOUNG_LIST_VERBOSE
2953 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
2954 _young_list->print();
2955 #endif // YOUNG_LIST_VERBOSE
2956
2957 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2958 _young_list->first_survivor_region(),
2959 _young_list->last_survivor_region());
2960
2961 _young_list->reset_auxilary_lists();
2962 }
2963
2964 if (evacuation_failed()) {
2965 _summary_bytes_used = recalculate_used();
2966 } else {
2967 // The "used" of the the collection set have already been subtracted
2968 // when they were freed. Add in the bytes evacuated.
2969 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2970 }
2971
2972 if (g1_policy()->in_young_gc_mode() &&
2973 g1_policy()->during_initial_mark_pause()) {
2974 concurrent_mark()->checkpointRootsInitialPost();
2975 set_marking_started();
2976 // CAUTION: after the doConcurrentMark() call below,
2977 // the concurrent marking thread(s) could be running
2978 // concurrently with us. Make sure that anything after
2979 // this point does not assume that we are the only GC thread
2980 // running. Note: of course, the actual marking work will
2981 // not start until the safepoint itself is released in
2982 // ConcurrentGCThread::safepoint_desynchronize().
2983 doConcurrentMark();
2984 }
2985
2986 #if YOUNG_LIST_VERBOSE
2987 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
2988 _young_list->print();
2989 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
2990 #endif // YOUNG_LIST_VERBOSE
2991
2992 double end_time_sec = os::elapsedTime();
2993 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2994 g1_policy()->record_pause_time_ms(pause_time_ms);
2995 g1_policy()->record_collection_pause_end();
2996
2997 assert(regions_accounted_for(), "Region leakage.");
2998
2999 MemoryService::track_memory_usage();
3000
3001 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3002 HandleMark hm; // Discard invalid handles created during verification
3003 gclog_or_tty->print(" VerifyAfterGC:");
3004 prepare_for_verify();
3005 Universe::verify(false);
3006 }
3007
3008 if (was_enabled) ref_processor()->enable_discovery();
3009
3010 {
3011 size_t expand_bytes = g1_policy()->expansion_amount();
3012 if (expand_bytes > 0) {
3013 size_t bytes_before = capacity();
3014 expand(expand_bytes);
3015 }
3016 }
3017
3018 if (mark_in_progress()) {
3019 concurrent_mark()->update_g1_committed();
3020 }
3021
3022 #ifdef TRACESPINNING
3023 ParallelTaskTerminator::print_termination_counts();
3024 #endif
3025
3026 gc_epilogue(false);
3027 }
3028
3029 assert(verify_region_lists(), "Bad region lists.");
3030
3031 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3032 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3033 print_tracing_info();
3034 vm_exit(-1);
3035 }
3036 }
3037
3038 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3039 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3040
3041 if (PrintHeapAtGC) {
3042 Universe::print_heap_after_gc();
3043 }
3044 if (G1SummarizeRSetStats &&
3045 (G1SummarizeRSetStatsPeriod > 0) &&
3046 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3047 g1_rem_set()->print_summary_info();
3048 }
3049 }
3050
3051 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3052 {
3053 size_t gclab_word_size;
3054 switch (purpose) {
3055 case GCAllocForSurvived:
3056 gclab_word_size = YoungPLABSize;
3057 break;
3058 case GCAllocForTenured:
3059 gclab_word_size = OldPLABSize;
3060 break;
3061 default:
3062 assert(false, "unknown GCAllocPurpose");
3063 gclab_word_size = OldPLABSize;
3064 break;
3065 }
3066 return gclab_word_size;
3067 }
3068
3069
3070 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3071 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3072 // make sure we don't call set_gc_alloc_region() multiple times on
3073 // the same region
3074 assert(r == NULL || !r->is_gc_alloc_region(),
3075 "shouldn't already be a GC alloc region");
3076 assert(r == NULL || !r->isHumongous(),
3077 "humongous regions shouldn't be used as GC alloc regions");
3078
3079 HeapWord* original_top = NULL;
3080 if (r != NULL)
3081 original_top = r->top();
3082
3083 // We will want to record the used space in r as being there before gc.
3084 // One we install it as a GC alloc region it's eligible for allocation.
3085 // So record it now and use it later.
3086 size_t r_used = 0;
3087 if (r != NULL) {
3088 r_used = r->used();
3089
3090 if (G1CollectedHeap::use_parallel_gc_threads()) {
3091 // need to take the lock to guard against two threads calling
3092 // get_gc_alloc_region concurrently (very unlikely but...)
3093 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3094 r->save_marks();
3095 }
3096 }
3097 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3098 _gc_alloc_regions[purpose] = r;
3099 if (old_alloc_region != NULL) {
3100 // Replace aliases too.
3101 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3102 if (_gc_alloc_regions[ap] == old_alloc_region) {
3103 _gc_alloc_regions[ap] = r;
3104 }
3105 }
3106 }
3107 if (r != NULL) {
3108 push_gc_alloc_region(r);
3109 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3110 // We are using a region as a GC alloc region after it has been used
3111 // as a mutator allocation region during the current marking cycle.
3112 // The mutator-allocated objects are currently implicitly marked, but
3113 // when we move hr->next_top_at_mark_start() forward at the the end
3114 // of the GC pause, they won't be. We therefore mark all objects in
3115 // the "gap". We do this object-by-object, since marking densely
3116 // does not currently work right with marking bitmap iteration. This
3117 // means we rely on TLAB filling at the start of pauses, and no
3118 // "resuscitation" of filled TLAB's. If we want to do this, we need
3119 // to fix the marking bitmap iteration.
3120 HeapWord* curhw = r->next_top_at_mark_start();
3121 HeapWord* t = original_top;
3122
3123 while (curhw < t) {
3124 oop cur = (oop)curhw;
3125 // We'll assume parallel for generality. This is rare code.
3126 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3127 curhw = curhw + cur->size();
3128 }
3129 assert(curhw == t, "Should have parsed correctly.");
3130 }
3131 if (G1PolicyVerbose > 1) {
3132 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3133 "for survivors:", r->bottom(), original_top, r->end());
3134 r->print();
3135 }
3136 g1_policy()->record_before_bytes(r_used);
3137 }
3138 }
3139
3140 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3141 assert(Thread::current()->is_VM_thread() ||
3142 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
3143 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3144 "Precondition.");
3145 hr->set_is_gc_alloc_region(true);
3146 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3147 _gc_alloc_region_list = hr;
3148 }
3149
3150 #ifdef G1_DEBUG
3151 class FindGCAllocRegion: public HeapRegionClosure {
3152 public:
3153 bool doHeapRegion(HeapRegion* r) {
3154 if (r->is_gc_alloc_region()) {
3155 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3156 r->hrs_index(), r->bottom());
3157 }
3158 return false;
3159 }
3160 };
3161 #endif // G1_DEBUG
3162
3163 void G1CollectedHeap::forget_alloc_region_list() {
3164 assert(Thread::current()->is_VM_thread(), "Precondition");
3165 while (_gc_alloc_region_list != NULL) {
3166 HeapRegion* r = _gc_alloc_region_list;
3167 assert(r->is_gc_alloc_region(), "Invariant.");
3168 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3169 // newly allocated data in order to be able to apply deferred updates
3170 // before the GC is done for verification purposes (i.e to allow
3171 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3172 // collection.
3173 r->ContiguousSpace::set_saved_mark();
3174 _gc_alloc_region_list = r->next_gc_alloc_region();
3175 r->set_next_gc_alloc_region(NULL);
3176 r->set_is_gc_alloc_region(false);
3177 if (r->is_survivor()) {
3178 if (r->is_empty()) {
3179 r->set_not_young();
3180 } else {
3181 _young_list->add_survivor_region(r);
3182 }
3183 }
3184 if (r->is_empty()) {
3185 ++_free_regions;
3186 }
3187 }
3188 #ifdef G1_DEBUG
3189 FindGCAllocRegion fa;
3190 heap_region_iterate(&fa);
3191 #endif // G1_DEBUG
3192 }
3193
3194
3195 bool G1CollectedHeap::check_gc_alloc_regions() {
3196 // TODO: allocation regions check
3197 return true;
3198 }
3199
3200 void G1CollectedHeap::get_gc_alloc_regions() {
3201 // First, let's check that the GC alloc region list is empty (it should)
3202 assert(_gc_alloc_region_list == NULL, "invariant");
3203
3204 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3205 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3206 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3207
3208 // Create new GC alloc regions.
3209 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3210 _retained_gc_alloc_regions[ap] = NULL;
3211
3212 if (alloc_region != NULL) {
3213 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3214
3215 // let's make sure that the GC alloc region is not tagged as such
3216 // outside a GC operation
3217 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3218
3219 if (alloc_region->in_collection_set() ||
3220 alloc_region->top() == alloc_region->end() ||
3221 alloc_region->top() == alloc_region->bottom() ||
3222 alloc_region->isHumongous()) {
3223 // we will discard the current GC alloc region if
3224 // * it's in the collection set (it can happen!),
3225 // * it's already full (no point in using it),
3226 // * it's empty (this means that it was emptied during
3227 // a cleanup and it should be on the free list now), or
3228 // * it's humongous (this means that it was emptied
3229 // during a cleanup and was added to the free list, but
3230 // has been subseqently used to allocate a humongous
3231 // object that may be less than the region size).
3232
3233 alloc_region = NULL;
3234 }
3235 }
3236
3237 if (alloc_region == NULL) {
3238 // we will get a new GC alloc region
3239 alloc_region = newAllocRegionWithExpansion(ap, 0);
3240 } else {
3241 // the region was retained from the last collection
3242 ++_gc_alloc_region_counts[ap];
3243 if (G1PrintHeapRegions) {
3244 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
3245 "top "PTR_FORMAT,
3246 alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
3247 }
3248 }
3249
3250 if (alloc_region != NULL) {
3251 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3252 set_gc_alloc_region(ap, alloc_region);
3253 }
3254
3255 assert(_gc_alloc_regions[ap] == NULL ||
3256 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3257 "the GC alloc region should be tagged as such");
3258 assert(_gc_alloc_regions[ap] == NULL ||
3259 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3260 "the GC alloc region should be the same as the GC alloc list head");
3261 }
3262 // Set alternative regions for allocation purposes that have reached
3263 // their limit.
3264 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3265 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3266 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3267 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3268 }
3269 }
3270 assert(check_gc_alloc_regions(), "alloc regions messed up");
3271 }
3272
3273 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3274 // We keep a separate list of all regions that have been alloc regions in
3275 // the current collection pause. Forget that now. This method will
3276 // untag the GC alloc regions and tear down the GC alloc region
3277 // list. It's desirable that no regions are tagged as GC alloc
3278 // outside GCs.
3279 forget_alloc_region_list();
3280
3281 // The current alloc regions contain objs that have survived
3282 // collection. Make them no longer GC alloc regions.
3283 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3284 HeapRegion* r = _gc_alloc_regions[ap];
3285 _retained_gc_alloc_regions[ap] = NULL;
3286 _gc_alloc_region_counts[ap] = 0;
3287
3288 if (r != NULL) {
3289 // we retain nothing on _gc_alloc_regions between GCs
3290 set_gc_alloc_region(ap, NULL);
3291
3292 if (r->is_empty()) {
3293 // we didn't actually allocate anything in it; let's just put
3294 // it on the free list
3295 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3296 r->set_zero_fill_complete();
3297 put_free_region_on_list_locked(r);
3298 } else if (_retain_gc_alloc_region[ap] && !totally) {
3299 // retain it so that we can use it at the beginning of the next GC
3300 _retained_gc_alloc_regions[ap] = r;
3301 }
3302 }
3303 }
3304 }
3305
3306 #ifndef PRODUCT
3307 // Useful for debugging
3308
3309 void G1CollectedHeap::print_gc_alloc_regions() {
3310 gclog_or_tty->print_cr("GC alloc regions");
3311 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3312 HeapRegion* r = _gc_alloc_regions[ap];
3313 if (r == NULL) {
3314 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3315 } else {
3316 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3317 ap, r->bottom(), r->used());
3318 }
3319 }
3320 }
3321 #endif // PRODUCT
3322
3323 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3324 _drain_in_progress = false;
3325 set_evac_failure_closure(cl);
3326 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3327 }
3328
3329 void G1CollectedHeap::finalize_for_evac_failure() {
3330 assert(_evac_failure_scan_stack != NULL &&
3331 _evac_failure_scan_stack->length() == 0,
3332 "Postcondition");
3333 assert(!_drain_in_progress, "Postcondition");
3334 delete _evac_failure_scan_stack;
3335 _evac_failure_scan_stack = NULL;
3336 }
3337
3338
3339
3340 // *** Sequential G1 Evacuation
3341
3342 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3343 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3344 // let the caller handle alloc failure
3345 if (alloc_region == NULL) return NULL;
3346 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3347 "Either the object is humongous or the region isn't");
3348 HeapWord* block = alloc_region->allocate(word_size);
3349 if (block == NULL) {
3350 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3351 }
3352 return block;
3353 }
3354
3355 class G1IsAliveClosure: public BoolObjectClosure {
3356 G1CollectedHeap* _g1;
3357 public:
3358 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3359 void do_object(oop p) { assert(false, "Do not call."); }
3360 bool do_object_b(oop p) {
3361 // It is reachable if it is outside the collection set, or is inside
3362 // and forwarded.
3363
3364 #ifdef G1_DEBUG
3365 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3366 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3367 !_g1->obj_in_cs(p) || p->is_forwarded());
3368 #endif // G1_DEBUG
3369
3370 return !_g1->obj_in_cs(p) || p->is_forwarded();
3371 }
3372 };
3373
3374 class G1KeepAliveClosure: public OopClosure {
3375 G1CollectedHeap* _g1;
3376 public:
3377 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3378 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3379 void do_oop( oop* p) {
3380 oop obj = *p;
3381 #ifdef G1_DEBUG
3382 if (PrintGC && Verbose) {
3383 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3384 p, (void*) obj, (void*) *p);
3385 }
3386 #endif // G1_DEBUG
3387
3388 if (_g1->obj_in_cs(obj)) {
3389 assert( obj->is_forwarded(), "invariant" );
3390 *p = obj->forwardee();
3391 #ifdef G1_DEBUG
3392 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3393 (void*) obj, (void*) *p);
3394 #endif // G1_DEBUG
3395 }
3396 }
3397 };
3398
3399 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3400 private:
3401 G1CollectedHeap* _g1;
3402 DirtyCardQueue *_dcq;
3403 CardTableModRefBS* _ct_bs;
3404
3405 public:
3406 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3407 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3408
3409 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3410 virtual void do_oop( oop* p) { do_oop_work(p); }
3411 template <class T> void do_oop_work(T* p) {
3412 assert(_from->is_in_reserved(p), "paranoia");
3413 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3414 !_from->is_survivor()) {
3415 size_t card_index = _ct_bs->index_for(p);
3416 if (_ct_bs->mark_card_deferred(card_index)) {
3417 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3418 }
3419 }
3420 }
3421 };
3422
3423 class RemoveSelfPointerClosure: public ObjectClosure {
3424 private:
3425 G1CollectedHeap* _g1;
3426 ConcurrentMark* _cm;
3427 HeapRegion* _hr;
3428 size_t _prev_marked_bytes;
3429 size_t _next_marked_bytes;
3430 OopsInHeapRegionClosure *_cl;
3431 public:
3432 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3433 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3434 _next_marked_bytes(0), _cl(cl) {}
3435
3436 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3437 size_t next_marked_bytes() { return _next_marked_bytes; }
3438
3439 // The original idea here was to coalesce evacuated and dead objects.
3440 // However that caused complications with the block offset table (BOT).
3441 // In particular if there were two TLABs, one of them partially refined.
3442 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3443 // The BOT entries of the unrefined part of TLAB_2 point to the start
3444 // of TLAB_2. If the last object of the TLAB_1 and the first object
3445 // of TLAB_2 are coalesced, then the cards of the unrefined part
3446 // would point into middle of the filler object.
3447 //
3448 // The current approach is to not coalesce and leave the BOT contents intact.
3449 void do_object(oop obj) {
3450 if (obj->is_forwarded() && obj->forwardee() == obj) {
3451 // The object failed to move.
3452 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3453 _cm->markPrev(obj);
3454 assert(_cm->isPrevMarked(obj), "Should be marked!");
3455 _prev_marked_bytes += (obj->size() * HeapWordSize);
3456 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3457 _cm->markAndGrayObjectIfNecessary(obj);
3458 }
3459 obj->set_mark(markOopDesc::prototype());
3460 // While we were processing RSet buffers during the
3461 // collection, we actually didn't scan any cards on the
3462 // collection set, since we didn't want to update remebered
3463 // sets with entries that point into the collection set, given
3464 // that live objects fromthe collection set are about to move
3465 // and such entries will be stale very soon. This change also
3466 // dealt with a reliability issue which involved scanning a
3467 // card in the collection set and coming across an array that
3468 // was being chunked and looking malformed. The problem is
3469 // that, if evacuation fails, we might have remembered set
3470 // entries missing given that we skipped cards on the
3471 // collection set. So, we'll recreate such entries now.
3472 obj->oop_iterate(_cl);
3473 assert(_cm->isPrevMarked(obj), "Should be marked!");
3474 } else {
3475 // The object has been either evacuated or is dead. Fill it with a
3476 // dummy object.
3477 MemRegion mr((HeapWord*)obj, obj->size());
3478 CollectedHeap::fill_with_object(mr);
3479 _cm->clearRangeBothMaps(mr);
3480 }
3481 }
3482 };
3483
3484 void G1CollectedHeap::remove_self_forwarding_pointers() {
3485 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3486 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3487 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3488 OopsInHeapRegionClosure *cl;
3489 if (G1DeferredRSUpdate) {
3490 cl = &deferred_update;
3491 } else {
3492 cl = &immediate_update;
3493 }
3494 HeapRegion* cur = g1_policy()->collection_set();
3495 while (cur != NULL) {
3496 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3497
3498 RemoveSelfPointerClosure rspc(_g1h, cl);
3499 if (cur->evacuation_failed()) {
3500 assert(cur->in_collection_set(), "bad CS");
3501 cl->set_region(cur);
3502 cur->object_iterate(&rspc);
3503
3504 // A number of manipulations to make the TAMS be the current top,
3505 // and the marked bytes be the ones observed in the iteration.
3506 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3507 // The comments below are the postconditions achieved by the
3508 // calls. Note especially the last such condition, which says that
3509 // the count of marked bytes has been properly restored.
3510 cur->note_start_of_marking(false);
3511 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3512 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3513 // _next_marked_bytes == prev_marked_bytes.
3514 cur->note_end_of_marking();
3515 // _prev_top_at_mark_start == top(),
3516 // _prev_marked_bytes == prev_marked_bytes
3517 }
3518 // If there is no mark in progress, we modified the _next variables
3519 // above needlessly, but harmlessly.
3520 if (_g1h->mark_in_progress()) {
3521 cur->note_start_of_marking(false);
3522 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3523 // _next_marked_bytes == next_marked_bytes.
3524 }
3525
3526 // Now make sure the region has the right index in the sorted array.
3527 g1_policy()->note_change_in_marked_bytes(cur);
3528 }
3529 cur = cur->next_in_collection_set();
3530 }
3531 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3532
3533 // Now restore saved marks, if any.
3534 if (_objs_with_preserved_marks != NULL) {
3535 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3536 assert(_objs_with_preserved_marks->length() ==
3537 _preserved_marks_of_objs->length(), "Both or none.");
3538 guarantee(_objs_with_preserved_marks->length() ==
3539 _preserved_marks_of_objs->length(), "Both or none.");
3540 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3541 oop obj = _objs_with_preserved_marks->at(i);
3542 markOop m = _preserved_marks_of_objs->at(i);
3543 obj->set_mark(m);
3544 }
3545 // Delete the preserved marks growable arrays (allocated on the C heap).
3546 delete _objs_with_preserved_marks;
3547 delete _preserved_marks_of_objs;
3548 _objs_with_preserved_marks = NULL;
3549 _preserved_marks_of_objs = NULL;
3550 }
3551 }
3552
3553 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3554 _evac_failure_scan_stack->push(obj);
3555 }
3556
3557 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3558 assert(_evac_failure_scan_stack != NULL, "precondition");
3559
3560 while (_evac_failure_scan_stack->length() > 0) {
3561 oop obj = _evac_failure_scan_stack->pop();
3562 _evac_failure_closure->set_region(heap_region_containing(obj));
3563 obj->oop_iterate_backwards(_evac_failure_closure);
3564 }
3565 }
3566
3567 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3568 markOop m = old->mark();
3569 // forward to self
3570 assert(!old->is_forwarded(), "precondition");
3571
3572 old->forward_to(old);
3573 handle_evacuation_failure_common(old, m);
3574 }
3575
3576 oop
3577 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3578 oop old) {
3579 markOop m = old->mark();
3580 oop forward_ptr = old->forward_to_atomic(old);
3581 if (forward_ptr == NULL) {
3582 // Forward-to-self succeeded.
3583 if (_evac_failure_closure != cl) {
3584 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3585 assert(!_drain_in_progress,
3586 "Should only be true while someone holds the lock.");
3587 // Set the global evac-failure closure to the current thread's.
3588 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3589 set_evac_failure_closure(cl);
3590 // Now do the common part.
3591 handle_evacuation_failure_common(old, m);
3592 // Reset to NULL.
3593 set_evac_failure_closure(NULL);
3594 } else {
3595 // The lock is already held, and this is recursive.
3596 assert(_drain_in_progress, "This should only be the recursive case.");
3597 handle_evacuation_failure_common(old, m);
3598 }
3599 return old;
3600 } else {
3601 // Someone else had a place to copy it.
3602 return forward_ptr;
3603 }
3604 }
3605
3606 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3607 set_evacuation_failed(true);
3608
3609 preserve_mark_if_necessary(old, m);
3610
3611 HeapRegion* r = heap_region_containing(old);
3612 if (!r->evacuation_failed()) {
3613 r->set_evacuation_failed(true);
3614 if (G1PrintHeapRegions) {
3615 gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
3616 "["PTR_FORMAT","PTR_FORMAT")\n",
3617 r, r->bottom(), r->end());
3618 }
3619 }
3620
3621 push_on_evac_failure_scan_stack(old);
3622
3623 if (!_drain_in_progress) {
3624 // prevent recursion in copy_to_survivor_space()
3625 _drain_in_progress = true;
3626 drain_evac_failure_scan_stack();
3627 _drain_in_progress = false;
3628 }
3629 }
3630
3631 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3632 if (m != markOopDesc::prototype()) {
3633 if (_objs_with_preserved_marks == NULL) {
3634 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3635 _objs_with_preserved_marks =
3636 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3637 _preserved_marks_of_objs =
3638 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3639 }
3640 _objs_with_preserved_marks->push(obj);
3641 _preserved_marks_of_objs->push(m);
3642 }
3643 }
3644
3645 // *** Parallel G1 Evacuation
3646
3647 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3648 size_t word_size) {
3649 assert(!isHumongous(word_size),
3650 err_msg("we should not be seeing humongous allocation requests "
3651 "during GC, word_size = "SIZE_FORMAT, word_size));
3652
3653 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3654 // let the caller handle alloc failure
3655 if (alloc_region == NULL) return NULL;
3656
3657 HeapWord* block = alloc_region->par_allocate(word_size);
3658 if (block == NULL) {
3659 MutexLockerEx x(par_alloc_during_gc_lock(),
3660 Mutex::_no_safepoint_check_flag);
3661 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3662 }
3663 return block;
3664 }
3665
3666 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3667 bool par) {
3668 // Another thread might have obtained alloc_region for the given
3669 // purpose, and might be attempting to allocate in it, and might
3670 // succeed. Therefore, we can't do the "finalization" stuff on the
3671 // region below until we're sure the last allocation has happened.
3672 // We ensure this by allocating the remaining space with a garbage
3673 // object.
3674 if (par) par_allocate_remaining_space(alloc_region);
3675 // Now we can do the post-GC stuff on the region.
3676 alloc_region->note_end_of_copying();
3677 g1_policy()->record_after_bytes(alloc_region->used());
3678 }
3679
3680 HeapWord*
3681 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3682 HeapRegion* alloc_region,
3683 bool par,
3684 size_t word_size) {
3685 assert(!isHumongous(word_size),
3686 err_msg("we should not be seeing humongous allocation requests "
3687 "during GC, word_size = "SIZE_FORMAT, word_size));
3688
3689 HeapWord* block = NULL;
3690 // In the parallel case, a previous thread to obtain the lock may have
3691 // already assigned a new gc_alloc_region.
3692 if (alloc_region != _gc_alloc_regions[purpose]) {
3693 assert(par, "But should only happen in parallel case.");
3694 alloc_region = _gc_alloc_regions[purpose];
3695 if (alloc_region == NULL) return NULL;
3696 block = alloc_region->par_allocate(word_size);
3697 if (block != NULL) return block;
3698 // Otherwise, continue; this new region is empty, too.
3699 }
3700 assert(alloc_region != NULL, "We better have an allocation region");
3701 retire_alloc_region(alloc_region, par);
3702
3703 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3704 // Cannot allocate more regions for the given purpose.
3705 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3706 // Is there an alternative?
3707 if (purpose != alt_purpose) {
3708 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3709 // Has not the alternative region been aliased?
3710 if (alloc_region != alt_region && alt_region != NULL) {
3711 // Try to allocate in the alternative region.
3712 if (par) {
3713 block = alt_region->par_allocate(word_size);
3714 } else {
3715 block = alt_region->allocate(word_size);
3716 }
3717 // Make an alias.
3718 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3719 if (block != NULL) {
3720 return block;
3721 }
3722 retire_alloc_region(alt_region, par);
3723 }
3724 // Both the allocation region and the alternative one are full
3725 // and aliased, replace them with a new allocation region.
3726 purpose = alt_purpose;
3727 } else {
3728 set_gc_alloc_region(purpose, NULL);
3729 return NULL;
3730 }
3731 }
3732
3733 // Now allocate a new region for allocation.
3734 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3735
3736 // let the caller handle alloc failure
3737 if (alloc_region != NULL) {
3738
3739 assert(check_gc_alloc_regions(), "alloc regions messed up");
3740 assert(alloc_region->saved_mark_at_top(),
3741 "Mark should have been saved already.");
3742 // We used to assert that the region was zero-filled here, but no
3743 // longer.
3744
3745 // This must be done last: once it's installed, other regions may
3746 // allocate in it (without holding the lock.)
3747 set_gc_alloc_region(purpose, alloc_region);
3748
3749 if (par) {
3750 block = alloc_region->par_allocate(word_size);
3751 } else {
3752 block = alloc_region->allocate(word_size);
3753 }
3754 // Caller handles alloc failure.
3755 } else {
3756 // This sets other apis using the same old alloc region to NULL, also.
3757 set_gc_alloc_region(purpose, NULL);
3758 }
3759 return block; // May be NULL.
3760 }
3761
3762 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3763 HeapWord* block = NULL;
3764 size_t free_words;
3765 do {
3766 free_words = r->free()/HeapWordSize;
3767 // If there's too little space, no one can allocate, so we're done.
3768 if (free_words < CollectedHeap::min_fill_size()) return;
3769 // Otherwise, try to claim it.
3770 block = r->par_allocate(free_words);
3771 } while (block == NULL);
3772 fill_with_object(block, free_words);
3773 }
3774
3775 #ifndef PRODUCT
3776 bool GCLabBitMapClosure::do_bit(size_t offset) {
3777 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3778 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3779 return true;
3780 }
3781 #endif // PRODUCT
3782
3783 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3784 : _g1h(g1h),
3785 _refs(g1h->task_queue(queue_num)),
3786 _dcq(&g1h->dirty_card_queue_set()),
3787 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3788 _g1_rem(g1h->g1_rem_set()),
3789 _hash_seed(17), _queue_num(queue_num),
3790 _term_attempts(0),
3791 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
3792 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
3793 _age_table(false),
3794 _strong_roots_time(0), _term_time(0),
3795 _alloc_buffer_waste(0), _undo_waste(0)
3796 {
3797 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3798 // we "sacrifice" entry 0 to keep track of surviving bytes for
3799 // non-young regions (where the age is -1)
3800 // We also add a few elements at the beginning and at the end in
3801 // an attempt to eliminate cache contention
3802 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3803 size_t array_length = PADDING_ELEM_NUM +
3804 real_length +
3805 PADDING_ELEM_NUM;
3806 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3807 if (_surviving_young_words_base == NULL)
3808 vm_exit_out_of_memory(array_length * sizeof(size_t),
3809 "Not enough space for young surv histo.");
3810 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3811 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3812
3813 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
3814 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
3815
3816 _start = os::elapsedTime();
3817 }
3818
3819 void
3820 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
3821 {
3822 st->print_raw_cr("GC Termination Stats");
3823 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
3824 " ------waste (KiB)------");
3825 st->print_raw_cr("thr ms ms % ms % attempts"
3826 " total alloc undo");
3827 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
3828 " ------- ------- -------");
3829 }
3830
3831 void
3832 G1ParScanThreadState::print_termination_stats(int i,
3833 outputStream* const st) const
3834 {
3835 const double elapsed_ms = elapsed_time() * 1000.0;
3836 const double s_roots_ms = strong_roots_time() * 1000.0;
3837 const double term_ms = term_time() * 1000.0;
3838 st->print_cr("%3d %9.2f %9.2f %6.2f "
3839 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3840 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3841 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
3842 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
3843 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
3844 alloc_buffer_waste() * HeapWordSize / K,
3845 undo_waste() * HeapWordSize / K);
3846 }
3847
3848 #ifdef ASSERT
3849 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
3850 assert(ref != NULL, "invariant");
3851 assert(UseCompressedOops, "sanity");
3852 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
3853 oop p = oopDesc::load_decode_heap_oop(ref);
3854 assert(_g1h->is_in_g1_reserved(p),
3855 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
3856 return true;
3857 }
3858
3859 bool G1ParScanThreadState::verify_ref(oop* ref) const {
3860 assert(ref != NULL, "invariant");
3861 if (has_partial_array_mask(ref)) {
3862 // Must be in the collection set--it's already been copied.
3863 oop p = clear_partial_array_mask(ref);
3864 assert(_g1h->obj_in_cs(p),
3865 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
3866 } else {
3867 oop p = oopDesc::load_decode_heap_oop(ref);
3868 assert(_g1h->is_in_g1_reserved(p),
3869 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
3870 }
3871 return true;
3872 }
3873
3874 bool G1ParScanThreadState::verify_task(StarTask ref) const {
3875 if (ref.is_narrow()) {
3876 return verify_ref((narrowOop*) ref);
3877 } else {
3878 return verify_ref((oop*) ref);
3879 }
3880 }
3881 #endif // ASSERT
3882
3883 void G1ParScanThreadState::trim_queue() {
3884 StarTask ref;
3885 do {
3886 // Drain the overflow stack first, so other threads can steal.
3887 while (refs()->pop_overflow(ref)) {
3888 deal_with_reference(ref);
3889 }
3890 while (refs()->pop_local(ref)) {
3891 deal_with_reference(ref);
3892 }
3893 } while (!refs()->is_empty());
3894 }
3895
3896 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3897 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3898 _par_scan_state(par_scan_state) { }
3899
3900 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3901 // This is called _after_ do_oop_work has been called, hence after
3902 // the object has been relocated to its new location and *p points
3903 // to its new location.
3904
3905 T heap_oop = oopDesc::load_heap_oop(p);
3906 if (!oopDesc::is_null(heap_oop)) {
3907 oop obj = oopDesc::decode_heap_oop(heap_oop);
3908 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3909 "shouldn't still be in the CSet if evacuation didn't fail.");
3910 HeapWord* addr = (HeapWord*)obj;
3911 if (_g1->is_in_g1_reserved(addr))
3912 _cm->grayRoot(oop(addr));
3913 }
3914 }
3915
3916 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3917 size_t word_sz = old->size();
3918 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3919 // +1 to make the -1 indexes valid...
3920 int young_index = from_region->young_index_in_cset()+1;
3921 assert( (from_region->is_young() && young_index > 0) ||
3922 (!from_region->is_young() && young_index == 0), "invariant" );
3923 G1CollectorPolicy* g1p = _g1->g1_policy();
3924 markOop m = old->mark();
3925 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3926 : m->age();
3927 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3928 word_sz);
3929 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3930 oop obj = oop(obj_ptr);
3931
3932 if (obj_ptr == NULL) {
3933 // This will either forward-to-self, or detect that someone else has
3934 // installed a forwarding pointer.
3935 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3936 return _g1->handle_evacuation_failure_par(cl, old);
3937 }
3938
3939 // We're going to allocate linearly, so might as well prefetch ahead.
3940 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3941
3942 oop forward_ptr = old->forward_to_atomic(obj);
3943 if (forward_ptr == NULL) {
3944 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3945 if (g1p->track_object_age(alloc_purpose)) {
3946 // We could simply do obj->incr_age(). However, this causes a
3947 // performance issue. obj->incr_age() will first check whether
3948 // the object has a displaced mark by checking its mark word;
3949 // getting the mark word from the new location of the object
3950 // stalls. So, given that we already have the mark word and we
3951 // are about to install it anyway, it's better to increase the
3952 // age on the mark word, when the object does not have a
3953 // displaced mark word. We're not expecting many objects to have
3954 // a displaced marked word, so that case is not optimized
3955 // further (it could be...) and we simply call obj->incr_age().
3956
3957 if (m->has_displaced_mark_helper()) {
3958 // in this case, we have to install the mark word first,
3959 // otherwise obj looks to be forwarded (the old mark word,
3960 // which contains the forward pointer, was copied)
3961 obj->set_mark(m);
3962 obj->incr_age();
3963 } else {
3964 m = m->incr_age();
3965 obj->set_mark(m);
3966 }
3967 _par_scan_state->age_table()->add(obj, word_sz);
3968 } else {
3969 obj->set_mark(m);
3970 }
3971
3972 // preserve "next" mark bit
3973 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3974 if (!use_local_bitmaps ||
3975 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3976 // if we couldn't mark it on the local bitmap (this happens when
3977 // the object was not allocated in the GCLab), we have to bite
3978 // the bullet and do the standard parallel mark
3979 _cm->markAndGrayObjectIfNecessary(obj);
3980 }
3981 #if 1
3982 if (_g1->isMarkedNext(old)) {
3983 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3984 }
3985 #endif
3986 }
3987
3988 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3989 surv_young_words[young_index] += word_sz;
3990
3991 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3992 arrayOop(old)->set_length(0);
3993 oop* old_p = set_partial_array_mask(old);
3994 _par_scan_state->push_on_queue(old_p);
3995 } else {
3996 // No point in using the slower heap_region_containing() method,
3997 // given that we know obj is in the heap.
3998 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3999 obj->oop_iterate_backwards(_scanner);
4000 }
4001 } else {
4002 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4003 obj = forward_ptr;
4004 }
4005 return obj;
4006 }
4007
4008 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4009 template <class T>
4010 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4011 ::do_oop_work(T* p) {
4012 oop obj = oopDesc::load_decode_heap_oop(p);
4013 assert(barrier != G1BarrierRS || obj != NULL,
4014 "Precondition: G1BarrierRS implies obj is nonNull");
4015
4016 // here the null check is implicit in the cset_fast_test() test
4017 if (_g1->in_cset_fast_test(obj)) {
4018 #if G1_REM_SET_LOGGING
4019 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4020 "into CS.", p, (void*) obj);
4021 #endif
4022 if (obj->is_forwarded()) {
4023 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4024 } else {
4025 oop copy_oop = copy_to_survivor_space(obj);
4026 oopDesc::encode_store_heap_oop(p, copy_oop);
4027 }
4028 // When scanning the RS, we only care about objs in CS.
4029 if (barrier == G1BarrierRS) {
4030 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4031 }
4032 }
4033
4034 if (barrier == G1BarrierEvac && obj != NULL) {
4035 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4036 }
4037
4038 if (do_gen_barrier && obj != NULL) {
4039 par_do_barrier(p);
4040 }
4041 }
4042
4043 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4044 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4045
4046 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4047 assert(has_partial_array_mask(p), "invariant");
4048 oop old = clear_partial_array_mask(p);
4049 assert(old->is_objArray(), "must be obj array");
4050 assert(old->is_forwarded(), "must be forwarded");
4051 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4052
4053 objArrayOop obj = objArrayOop(old->forwardee());
4054 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4055 // Process ParGCArrayScanChunk elements now
4056 // and push the remainder back onto queue
4057 int start = arrayOop(old)->length();
4058 int end = obj->length();
4059 int remainder = end - start;
4060 assert(start <= end, "just checking");
4061 if (remainder > 2 * ParGCArrayScanChunk) {
4062 // Test above combines last partial chunk with a full chunk
4063 end = start + ParGCArrayScanChunk;
4064 arrayOop(old)->set_length(end);
4065 // Push remainder.
4066 oop* old_p = set_partial_array_mask(old);
4067 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4068 _par_scan_state->push_on_queue(old_p);
4069 } else {
4070 // Restore length so that the heap remains parsable in
4071 // case of evacuation failure.
4072 arrayOop(old)->set_length(end);
4073 }
4074 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4075 // process our set of indices (include header in first chunk)
4076 obj->oop_iterate_range(&_scanner, start, end);
4077 }
4078
4079 class G1ParEvacuateFollowersClosure : public VoidClosure {
4080 protected:
4081 G1CollectedHeap* _g1h;
4082 G1ParScanThreadState* _par_scan_state;
4083 RefToScanQueueSet* _queues;
4084 ParallelTaskTerminator* _terminator;
4085
4086 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4087 RefToScanQueueSet* queues() { return _queues; }
4088 ParallelTaskTerminator* terminator() { return _terminator; }
4089
4090 public:
4091 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4092 G1ParScanThreadState* par_scan_state,
4093 RefToScanQueueSet* queues,
4094 ParallelTaskTerminator* terminator)
4095 : _g1h(g1h), _par_scan_state(par_scan_state),
4096 _queues(queues), _terminator(terminator) {}
4097
4098 void do_void();
4099
4100 private:
4101 inline bool offer_termination();
4102 };
4103
4104 bool G1ParEvacuateFollowersClosure::offer_termination() {
4105 G1ParScanThreadState* const pss = par_scan_state();
4106 pss->start_term_time();
4107 const bool res = terminator()->offer_termination();
4108 pss->end_term_time();
4109 return res;
4110 }
4111
4112 void G1ParEvacuateFollowersClosure::do_void() {
4113 StarTask stolen_task;
4114 G1ParScanThreadState* const pss = par_scan_state();
4115 pss->trim_queue();
4116
4117 do {
4118 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4119 assert(pss->verify_task(stolen_task), "sanity");
4120 if (stolen_task.is_narrow()) {
4121 pss->push_on_queue((narrowOop*) stolen_task);
4122 } else {
4123 pss->push_on_queue((oop*) stolen_task);
4124 }
4125 pss->trim_queue();
4126 }
4127 } while (!offer_termination());
4128
4129 pss->retire_alloc_buffers();
4130 }
4131
4132 class G1ParTask : public AbstractGangTask {
4133 protected:
4134 G1CollectedHeap* _g1h;
4135 RefToScanQueueSet *_queues;
4136 ParallelTaskTerminator _terminator;
4137 int _n_workers;
4138
4139 Mutex _stats_lock;
4140 Mutex* stats_lock() { return &_stats_lock; }
4141
4142 size_t getNCards() {
4143 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4144 / G1BlockOffsetSharedArray::N_bytes;
4145 }
4146
4147 public:
4148 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4149 : AbstractGangTask("G1 collection"),
4150 _g1h(g1h),
4151 _queues(task_queues),
4152 _terminator(workers, _queues),
4153 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4154 _n_workers(workers)
4155 {}
4156
4157 RefToScanQueueSet* queues() { return _queues; }
4158
4159 RefToScanQueue *work_queue(int i) {
4160 return queues()->queue(i);
4161 }
4162
4163 void work(int i) {
4164 if (i >= _n_workers) return; // no work needed this round
4165
4166 double start_time_ms = os::elapsedTime() * 1000.0;
4167 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4168
4169 ResourceMark rm;
4170 HandleMark hm;
4171
4172 G1ParScanThreadState pss(_g1h, i);
4173 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4174 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4175 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4176
4177 pss.set_evac_closure(&scan_evac_cl);
4178 pss.set_evac_failure_closure(&evac_failure_cl);
4179 pss.set_partial_scan_closure(&partial_scan_cl);
4180
4181 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4182 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4183 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4184 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4185
4186 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4187 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4188 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4189
4190 OopsInHeapRegionClosure *scan_root_cl;
4191 OopsInHeapRegionClosure *scan_perm_cl;
4192
4193 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4194 scan_root_cl = &scan_mark_root_cl;
4195 scan_perm_cl = &scan_mark_perm_cl;
4196 } else {
4197 scan_root_cl = &only_scan_root_cl;
4198 scan_perm_cl = &only_scan_perm_cl;
4199 }
4200
4201 pss.start_strong_roots();
4202 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4203 SharedHeap::SO_AllClasses,
4204 scan_root_cl,
4205 &push_heap_rs_cl,
4206 scan_perm_cl,
4207 i);
4208 pss.end_strong_roots();
4209 {
4210 double start = os::elapsedTime();
4211 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4212 evac.do_void();
4213 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4214 double term_ms = pss.term_time()*1000.0;
4215 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4216 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4217 }
4218 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4219 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4220
4221 // Clean up any par-expanded rem sets.
4222 HeapRegionRemSet::par_cleanup();
4223
4224 if (ParallelGCVerbose) {
4225 MutexLocker x(stats_lock());
4226 pss.print_termination_stats(i);
4227 }
4228
4229 assert(pss.refs()->is_empty(), "should be empty");
4230 double end_time_ms = os::elapsedTime() * 1000.0;
4231 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4232 }
4233 };
4234
4235 // *** Common G1 Evacuation Stuff
4236
4237 // This method is run in a GC worker.
4238
4239 void
4240 G1CollectedHeap::
4241 g1_process_strong_roots(bool collecting_perm_gen,
4242 SharedHeap::ScanningOption so,
4243 OopClosure* scan_non_heap_roots,
4244 OopsInHeapRegionClosure* scan_rs,
4245 OopsInGenClosure* scan_perm,
4246 int worker_i) {
4247 // First scan the strong roots, including the perm gen.
4248 double ext_roots_start = os::elapsedTime();
4249 double closure_app_time_sec = 0.0;
4250
4251 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4252 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4253 buf_scan_perm.set_generation(perm_gen());
4254
4255 // Walk the code cache w/o buffering, because StarTask cannot handle
4256 // unaligned oop locations.
4257 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4258
4259 process_strong_roots(false, // no scoping; this is parallel code
4260 collecting_perm_gen, so,
4261 &buf_scan_non_heap_roots,
4262 &eager_scan_code_roots,
4263 &buf_scan_perm);
4264
4265 // Finish up any enqueued closure apps.
4266 buf_scan_non_heap_roots.done();
4267 buf_scan_perm.done();
4268 double ext_roots_end = os::elapsedTime();
4269 g1_policy()->reset_obj_copy_time(worker_i);
4270 double obj_copy_time_sec =
4271 buf_scan_non_heap_roots.closure_app_seconds() +
4272 buf_scan_perm.closure_app_seconds();
4273 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4274 double ext_root_time_ms =
4275 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4276 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4277
4278 // Scan strong roots in mark stack.
4279 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4280 concurrent_mark()->oops_do(scan_non_heap_roots);
4281 }
4282 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4283 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4284
4285 // XXX What should this be doing in the parallel case?
4286 g1_policy()->record_collection_pause_end_CH_strong_roots();
4287 // Now scan the complement of the collection set.
4288 if (scan_rs != NULL) {
4289 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4290 }
4291 // Finish with the ref_processor roots.
4292 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4293 ref_processor()->oops_do(scan_non_heap_roots);
4294 }
4295 g1_policy()->record_collection_pause_end_G1_strong_roots();
4296 _process_strong_tasks->all_tasks_completed();
4297 }
4298
4299 void
4300 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4301 OopClosure* non_root_closure) {
4302 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4303 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4304 }
4305
4306
4307 class SaveMarksClosure: public HeapRegionClosure {
4308 public:
4309 bool doHeapRegion(HeapRegion* r) {
4310 r->save_marks();
4311 return false;
4312 }
4313 };
4314
4315 void G1CollectedHeap::save_marks() {
4316 if (!CollectedHeap::use_parallel_gc_threads()) {
4317 SaveMarksClosure sm;
4318 heap_region_iterate(&sm);
4319 }
4320 // We do this even in the parallel case
4321 perm_gen()->save_marks();
4322 }
4323
4324 void G1CollectedHeap::evacuate_collection_set() {
4325 set_evacuation_failed(false);
4326
4327 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4328 concurrent_g1_refine()->set_use_cache(false);
4329 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4330
4331 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4332 set_par_threads(n_workers);
4333 G1ParTask g1_par_task(this, n_workers, _task_queues);
4334
4335 init_for_evac_failure(NULL);
4336
4337 rem_set()->prepare_for_younger_refs_iterate(true);
4338
4339 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4340 double start_par = os::elapsedTime();
4341 if (G1CollectedHeap::use_parallel_gc_threads()) {
4342 // The individual threads will set their evac-failure closures.
4343 StrongRootsScope srs(this);
4344 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4345 workers()->run_task(&g1_par_task);
4346 } else {
4347 StrongRootsScope srs(this);
4348 g1_par_task.work(0);
4349 }
4350
4351 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4352 g1_policy()->record_par_time(par_time);
4353 set_par_threads(0);
4354 // Is this the right thing to do here? We don't save marks
4355 // on individual heap regions when we allocate from
4356 // them in parallel, so this seems like the correct place for this.
4357 retire_all_alloc_regions();
4358 {
4359 G1IsAliveClosure is_alive(this);
4360 G1KeepAliveClosure keep_alive(this);
4361 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4362 }
4363 release_gc_alloc_regions(false /* totally */);
4364 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4365
4366 concurrent_g1_refine()->clear_hot_cache();
4367 concurrent_g1_refine()->set_use_cache(true);
4368
4369 finalize_for_evac_failure();
4370
4371 // Must do this before removing self-forwarding pointers, which clears
4372 // the per-region evac-failure flags.
4373 concurrent_mark()->complete_marking_in_collection_set();
4374
4375 if (evacuation_failed()) {
4376 remove_self_forwarding_pointers();
4377 if (PrintGCDetails) {
4378 gclog_or_tty->print(" (to-space overflow)");
4379 } else if (PrintGC) {
4380 gclog_or_tty->print("--");
4381 }
4382 }
4383
4384 if (G1DeferredRSUpdate) {
4385 RedirtyLoggedCardTableEntryFastClosure redirty;
4386 dirty_card_queue_set().set_closure(&redirty);
4387 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4388
4389 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4390 dcq.merge_bufferlists(&dirty_card_queue_set());
4391 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4392 }
4393 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4394 }
4395
4396 void G1CollectedHeap::free_region(HeapRegion* hr) {
4397 size_t pre_used = 0;
4398 size_t cleared_h_regions = 0;
4399 size_t freed_regions = 0;
4400 UncleanRegionList local_list;
4401
4402 HeapWord* start = hr->bottom();
4403 HeapWord* end = hr->prev_top_at_mark_start();
4404 size_t used_bytes = hr->used();
4405 size_t live_bytes = hr->max_live_bytes();
4406 if (used_bytes > 0) {
4407 guarantee( live_bytes <= used_bytes, "invariant" );
4408 } else {
4409 guarantee( live_bytes == 0, "invariant" );
4410 }
4411
4412 size_t garbage_bytes = used_bytes - live_bytes;
4413 if (garbage_bytes > 0)
4414 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4415
4416 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4417 &local_list);
4418 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4419 &local_list);
4420 }
4421
4422 void
4423 G1CollectedHeap::free_region_work(HeapRegion* hr,
4424 size_t& pre_used,
4425 size_t& cleared_h_regions,
4426 size_t& freed_regions,
4427 UncleanRegionList* list,
4428 bool par) {
4429 pre_used += hr->used();
4430 if (hr->isHumongous()) {
4431 assert(hr->startsHumongous(),
4432 "Only the start of a humongous region should be freed.");
4433 int ind = _hrs->find(hr);
4434 assert(ind != -1, "Should have an index.");
4435 // Clear the start region.
4436 hr->hr_clear(par, true /*clear_space*/);
4437 list->insert_before_head(hr);
4438 cleared_h_regions++;
4439 freed_regions++;
4440 // Clear any continued regions.
4441 ind++;
4442 while ((size_t)ind < n_regions()) {
4443 HeapRegion* hrc = _hrs->at(ind);
4444 if (!hrc->continuesHumongous()) break;
4445 // Otherwise, does continue the H region.
4446 assert(hrc->humongous_start_region() == hr, "Huh?");
4447 hrc->hr_clear(par, true /*clear_space*/);
4448 cleared_h_regions++;
4449 freed_regions++;
4450 list->insert_before_head(hrc);
4451 ind++;
4452 }
4453 } else {
4454 hr->hr_clear(par, true /*clear_space*/);
4455 list->insert_before_head(hr);
4456 freed_regions++;
4457 // If we're using clear2, this should not be enabled.
4458 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4459 }
4460 }
4461
4462 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4463 size_t cleared_h_regions,
4464 size_t freed_regions,
4465 UncleanRegionList* list) {
4466 if (list != NULL && list->sz() > 0) {
4467 prepend_region_list_on_unclean_list(list);
4468 }
4469 // Acquire a lock, if we're parallel, to update possibly-shared
4470 // variables.
4471 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4472 {
4473 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4474 _summary_bytes_used -= pre_used;
4475 _num_humongous_regions -= (int) cleared_h_regions;
4476 _free_regions += freed_regions;
4477 }
4478 }
4479
4480
4481 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4482 while (list != NULL) {
4483 guarantee( list->is_young(), "invariant" );
4484
4485 HeapWord* bottom = list->bottom();
4486 HeapWord* end = list->end();
4487 MemRegion mr(bottom, end);
4488 ct_bs->dirty(mr);
4489
4490 list = list->get_next_young_region();
4491 }
4492 }
4493
4494
4495 class G1ParCleanupCTTask : public AbstractGangTask {
4496 CardTableModRefBS* _ct_bs;
4497 G1CollectedHeap* _g1h;
4498 HeapRegion* volatile _su_head;
4499 public:
4500 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4501 G1CollectedHeap* g1h,
4502 HeapRegion* survivor_list) :
4503 AbstractGangTask("G1 Par Cleanup CT Task"),
4504 _ct_bs(ct_bs),
4505 _g1h(g1h),
4506 _su_head(survivor_list)
4507 { }
4508
4509 void work(int i) {
4510 HeapRegion* r;
4511 while (r = _g1h->pop_dirty_cards_region()) {
4512 clear_cards(r);
4513 }
4514 // Redirty the cards of the survivor regions.
4515 dirty_list(&this->_su_head);
4516 }
4517
4518 void clear_cards(HeapRegion* r) {
4519 // Cards for Survivor regions will be dirtied later.
4520 if (!r->is_survivor()) {
4521 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4522 }
4523 }
4524
4525 void dirty_list(HeapRegion* volatile * head_ptr) {
4526 HeapRegion* head;
4527 do {
4528 // Pop region off the list.
4529 head = *head_ptr;
4530 if (head != NULL) {
4531 HeapRegion* r = (HeapRegion*)
4532 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4533 if (r == head) {
4534 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4535 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4536 }
4537 }
4538 } while (*head_ptr != NULL);
4539 }
4540 };
4541
4542
4543 #ifndef PRODUCT
4544 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4545 CardTableModRefBS* _ct_bs;
4546 public:
4547 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4548 : _ct_bs(ct_bs)
4549 { }
4550 virtual bool doHeapRegion(HeapRegion* r)
4551 {
4552 MemRegion mr(r->bottom(), r->end());
4553 if (r->is_survivor()) {
4554 _ct_bs->verify_dirty_region(mr);
4555 } else {
4556 _ct_bs->verify_clean_region(mr);
4557 }
4558 return false;
4559 }
4560 };
4561 #endif
4562
4563 void G1CollectedHeap::cleanUpCardTable() {
4564 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4565 double start = os::elapsedTime();
4566
4567 // Iterate over the dirty cards region list.
4568 G1ParCleanupCTTask cleanup_task(ct_bs, this,
4569 _young_list->first_survivor_region());
4570
4571 if (ParallelGCThreads > 0) {
4572 set_par_threads(workers()->total_workers());
4573 workers()->run_task(&cleanup_task);
4574 set_par_threads(0);
4575 } else {
4576 while (_dirty_cards_region_list) {
4577 HeapRegion* r = _dirty_cards_region_list;
4578 cleanup_task.clear_cards(r);
4579 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4580 if (_dirty_cards_region_list == r) {
4581 // The last region.
4582 _dirty_cards_region_list = NULL;
4583 }
4584 r->set_next_dirty_cards_region(NULL);
4585 }
4586 // now, redirty the cards of the survivor regions
4587 // (it seemed faster to do it this way, instead of iterating over
4588 // all regions and then clearing / dirtying as appropriate)
4589 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4590 }
4591
4592 double elapsed = os::elapsedTime() - start;
4593 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4594 #ifndef PRODUCT
4595 if (G1VerifyCTCleanup || VerifyAfterGC) {
4596 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
4597 heap_region_iterate(&cleanup_verifier);
4598 }
4599 #endif
4600 }
4601
4602 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4603 if (g1_policy()->should_do_collection_pause(word_size)) {
4604 do_collection_pause();
4605 }
4606 }
4607
4608 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4609 double young_time_ms = 0.0;
4610 double non_young_time_ms = 0.0;
4611
4612 // Since the collection set is a superset of the the young list,
4613 // all we need to do to clear the young list is clear its
4614 // head and length, and unlink any young regions in the code below
4615 _young_list->clear();
4616
4617 G1CollectorPolicy* policy = g1_policy();
4618
4619 double start_sec = os::elapsedTime();
4620 bool non_young = true;
4621
4622 HeapRegion* cur = cs_head;
4623 int age_bound = -1;
4624 size_t rs_lengths = 0;
4625
4626 while (cur != NULL) {
4627 if (non_young) {
4628 if (cur->is_young()) {
4629 double end_sec = os::elapsedTime();
4630 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4631 non_young_time_ms += elapsed_ms;
4632
4633 start_sec = os::elapsedTime();
4634 non_young = false;
4635 }
4636 } else {
4637 if (!cur->is_on_free_list()) {
4638 double end_sec = os::elapsedTime();
4639 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4640 young_time_ms += elapsed_ms;
4641
4642 start_sec = os::elapsedTime();
4643 non_young = true;
4644 }
4645 }
4646
4647 rs_lengths += cur->rem_set()->occupied();
4648
4649 HeapRegion* next = cur->next_in_collection_set();
4650 assert(cur->in_collection_set(), "bad CS");
4651 cur->set_next_in_collection_set(NULL);
4652 cur->set_in_collection_set(false);
4653
4654 if (cur->is_young()) {
4655 int index = cur->young_index_in_cset();
4656 guarantee( index != -1, "invariant" );
4657 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4658 size_t words_survived = _surviving_young_words[index];
4659 cur->record_surv_words_in_group(words_survived);
4660
4661 // At this point the we have 'popped' cur from the collection set
4662 // (linked via next_in_collection_set()) but it is still in the
4663 // young list (linked via next_young_region()). Clear the
4664 // _next_young_region field.
4665 cur->set_next_young_region(NULL);
4666 } else {
4667 int index = cur->young_index_in_cset();
4668 guarantee( index == -1, "invariant" );
4669 }
4670
4671 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4672 (!cur->is_young() && cur->young_index_in_cset() == -1),
4673 "invariant" );
4674
4675 if (!cur->evacuation_failed()) {
4676 // And the region is empty.
4677 assert(!cur->is_empty(),
4678 "Should not have empty regions in a CS.");
4679 free_region(cur);
4680 } else {
4681 cur->uninstall_surv_rate_group();
4682 if (cur->is_young())
4683 cur->set_young_index_in_cset(-1);
4684 cur->set_not_young();
4685 cur->set_evacuation_failed(false);
4686 }
4687 cur = next;
4688 }
4689
4690 policy->record_max_rs_lengths(rs_lengths);
4691 policy->cset_regions_freed();
4692
4693 double end_sec = os::elapsedTime();
4694 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4695 if (non_young)
4696 non_young_time_ms += elapsed_ms;
4697 else
4698 young_time_ms += elapsed_ms;
4699
4700 policy->record_young_free_cset_time_ms(young_time_ms);
4701 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4702 }
4703
4704 // This routine is similar to the above but does not record
4705 // any policy statistics or update free lists; we are abandoning
4706 // the current incremental collection set in preparation of a
4707 // full collection. After the full GC we will start to build up
4708 // the incremental collection set again.
4709 // This is only called when we're doing a full collection
4710 // and is immediately followed by the tearing down of the young list.
4711
4712 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
4713 HeapRegion* cur = cs_head;
4714
4715 while (cur != NULL) {
4716 HeapRegion* next = cur->next_in_collection_set();
4717 assert(cur->in_collection_set(), "bad CS");
4718 cur->set_next_in_collection_set(NULL);
4719 cur->set_in_collection_set(false);
4720 cur->set_young_index_in_cset(-1);
4721 cur = next;
4722 }
4723 }
4724
4725 HeapRegion*
4726 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4727 assert(ZF_mon->owned_by_self(), "Precondition");
4728 HeapRegion* res = pop_unclean_region_list_locked();
4729 if (res != NULL) {
4730 assert(!res->continuesHumongous() &&
4731 res->zero_fill_state() != HeapRegion::Allocated,
4732 "Only free regions on unclean list.");
4733 if (zero_filled) {
4734 res->ensure_zero_filled_locked();
4735 res->set_zero_fill_allocated();
4736 }
4737 }
4738 return res;
4739 }
4740
4741 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4742 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4743 return alloc_region_from_unclean_list_locked(zero_filled);
4744 }
4745
4746 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4747 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4748 put_region_on_unclean_list_locked(r);
4749 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4750 }
4751
4752 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4753 MutexLockerEx x(Cleanup_mon);
4754 set_unclean_regions_coming_locked(b);
4755 }
4756
4757 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4758 assert(Cleanup_mon->owned_by_self(), "Precondition");
4759 _unclean_regions_coming = b;
4760 // Wake up mutator threads that might be waiting for completeCleanup to
4761 // finish.
4762 if (!b) Cleanup_mon->notify_all();
4763 }
4764
4765 void G1CollectedHeap::wait_for_cleanup_complete() {
4766 MutexLockerEx x(Cleanup_mon);
4767 wait_for_cleanup_complete_locked();
4768 }
4769
4770 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4771 assert(Cleanup_mon->owned_by_self(), "precondition");
4772 while (_unclean_regions_coming) {
4773 Cleanup_mon->wait();
4774 }
4775 }
4776
4777 void
4778 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4779 assert(ZF_mon->owned_by_self(), "precondition.");
4780 #ifdef ASSERT
4781 if (r->is_gc_alloc_region()) {
4782 ResourceMark rm;
4783 stringStream region_str;
4784 print_on(®ion_str);
4785 assert(!r->is_gc_alloc_region(), err_msg("Unexpected GC allocation region: %s",
4786 region_str.as_string()));
4787 }
4788 #endif
4789 _unclean_region_list.insert_before_head(r);
4790 }
4791
4792 void
4793 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4794 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4795 prepend_region_list_on_unclean_list_locked(list);
4796 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4797 }
4798
4799 void
4800 G1CollectedHeap::
4801 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4802 assert(ZF_mon->owned_by_self(), "precondition.");
4803 _unclean_region_list.prepend_list(list);
4804 }
4805
4806 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4807 assert(ZF_mon->owned_by_self(), "precondition.");
4808 HeapRegion* res = _unclean_region_list.pop();
4809 if (res != NULL) {
4810 // Inform ZF thread that there's a new unclean head.
4811 if (_unclean_region_list.hd() != NULL && should_zf())
4812 ZF_mon->notify_all();
4813 }
4814 return res;
4815 }
4816
4817 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4818 assert(ZF_mon->owned_by_self(), "precondition.");
4819 return _unclean_region_list.hd();
4820 }
4821
4822
4823 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4824 assert(ZF_mon->owned_by_self(), "Precondition");
4825 HeapRegion* r = peek_unclean_region_list_locked();
4826 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4827 // Result of below must be equal to "r", since we hold the lock.
4828 (void)pop_unclean_region_list_locked();
4829 put_free_region_on_list_locked(r);
4830 return true;
4831 } else {
4832 return false;
4833 }
4834 }
4835
4836 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4837 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4838 return move_cleaned_region_to_free_list_locked();
4839 }
4840
4841
4842 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4843 assert(ZF_mon->owned_by_self(), "precondition.");
4844 assert(_free_region_list_size == free_region_list_length(), "Inv");
4845 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4846 "Regions on free list must be zero filled");
4847 assert(!r->isHumongous(), "Must not be humongous.");
4848 assert(r->is_empty(), "Better be empty");
4849 assert(!r->is_on_free_list(),
4850 "Better not already be on free list");
4851 assert(!r->is_on_unclean_list(),
4852 "Better not already be on unclean list");
4853 r->set_on_free_list(true);
4854 r->set_next_on_free_list(_free_region_list);
4855 _free_region_list = r;
4856 _free_region_list_size++;
4857 assert(_free_region_list_size == free_region_list_length(), "Inv");
4858 }
4859
4860 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4861 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4862 put_free_region_on_list_locked(r);
4863 }
4864
4865 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4866 assert(ZF_mon->owned_by_self(), "precondition.");
4867 assert(_free_region_list_size == free_region_list_length(), "Inv");
4868 HeapRegion* res = _free_region_list;
4869 if (res != NULL) {
4870 _free_region_list = res->next_from_free_list();
4871 _free_region_list_size--;
4872 res->set_on_free_list(false);
4873 res->set_next_on_free_list(NULL);
4874 assert(_free_region_list_size == free_region_list_length(), "Inv");
4875 }
4876 return res;
4877 }
4878
4879
4880 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4881 // By self, or on behalf of self.
4882 assert(Heap_lock->is_locked(), "Precondition");
4883 HeapRegion* res = NULL;
4884 bool first = true;
4885 while (res == NULL) {
4886 if (zero_filled || !first) {
4887 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4888 res = pop_free_region_list_locked();
4889 if (res != NULL) {
4890 assert(!res->zero_fill_is_allocated(),
4891 "No allocated regions on free list.");
4892 res->set_zero_fill_allocated();
4893 } else if (!first) {
4894 break; // We tried both, time to return NULL.
4895 }
4896 }
4897
4898 if (res == NULL) {
4899 res = alloc_region_from_unclean_list(zero_filled);
4900 }
4901 assert(res == NULL ||
4902 !zero_filled ||
4903 res->zero_fill_is_allocated(),
4904 "We must have allocated the region we're returning");
4905 first = false;
4906 }
4907 return res;
4908 }
4909
4910 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4911 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4912 {
4913 HeapRegion* prev = NULL;
4914 HeapRegion* cur = _unclean_region_list.hd();
4915 while (cur != NULL) {
4916 HeapRegion* next = cur->next_from_unclean_list();
4917 if (cur->zero_fill_is_allocated()) {
4918 // Remove from the list.
4919 if (prev == NULL) {
4920 (void)_unclean_region_list.pop();
4921 } else {
4922 _unclean_region_list.delete_after(prev);
4923 }
4924 cur->set_on_unclean_list(false);
4925 cur->set_next_on_unclean_list(NULL);
4926 } else {
4927 prev = cur;
4928 }
4929 cur = next;
4930 }
4931 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4932 "Inv");
4933 }
4934
4935 {
4936 HeapRegion* prev = NULL;
4937 HeapRegion* cur = _free_region_list;
4938 while (cur != NULL) {
4939 HeapRegion* next = cur->next_from_free_list();
4940 if (cur->zero_fill_is_allocated()) {
4941 // Remove from the list.
4942 if (prev == NULL) {
4943 _free_region_list = cur->next_from_free_list();
4944 } else {
4945 prev->set_next_on_free_list(cur->next_from_free_list());
4946 }
4947 cur->set_on_free_list(false);
4948 cur->set_next_on_free_list(NULL);
4949 _free_region_list_size--;
4950 } else {
4951 prev = cur;
4952 }
4953 cur = next;
4954 }
4955 assert(_free_region_list_size == free_region_list_length(), "Inv");
4956 }
4957 }
4958
4959 bool G1CollectedHeap::verify_region_lists() {
4960 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4961 return verify_region_lists_locked();
4962 }
4963
4964 bool G1CollectedHeap::verify_region_lists_locked() {
4965 HeapRegion* unclean = _unclean_region_list.hd();
4966 while (unclean != NULL) {
4967 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4968 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4969 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4970 "Everything else is possible.");
4971 unclean = unclean->next_from_unclean_list();
4972 }
4973 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4974
4975 HeapRegion* free_r = _free_region_list;
4976 while (free_r != NULL) {
4977 assert(free_r->is_on_free_list(), "Well, it is!");
4978 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4979 switch (free_r->zero_fill_state()) {
4980 case HeapRegion::NotZeroFilled:
4981 case HeapRegion::ZeroFilling:
4982 guarantee(false, "Should not be on free list.");
4983 break;
4984 default:
4985 // Everything else is possible.
4986 break;
4987 }
4988 free_r = free_r->next_from_free_list();
4989 }
4990 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4991 // If we didn't do an assertion...
4992 return true;
4993 }
4994
4995 size_t G1CollectedHeap::free_region_list_length() {
4996 assert(ZF_mon->owned_by_self(), "precondition.");
4997 size_t len = 0;
4998 HeapRegion* cur = _free_region_list;
4999 while (cur != NULL) {
5000 len++;
5001 cur = cur->next_from_free_list();
5002 }
5003 return len;
5004 }
5005
5006 size_t G1CollectedHeap::unclean_region_list_length() {
5007 assert(ZF_mon->owned_by_self(), "precondition.");
5008 return _unclean_region_list.length();
5009 }
5010
5011 size_t G1CollectedHeap::n_regions() {
5012 return _hrs->length();
5013 }
5014
5015 size_t G1CollectedHeap::max_regions() {
5016 return
5017 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5018 HeapRegion::GrainBytes;
5019 }
5020
5021 size_t G1CollectedHeap::free_regions() {
5022 /* Possibly-expensive assert.
5023 assert(_free_regions == count_free_regions(),
5024 "_free_regions is off.");
5025 */
5026 return _free_regions;
5027 }
5028
5029 bool G1CollectedHeap::should_zf() {
5030 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5031 }
5032
5033 class RegionCounter: public HeapRegionClosure {
5034 size_t _n;
5035 public:
5036 RegionCounter() : _n(0) {}
5037 bool doHeapRegion(HeapRegion* r) {
5038 if (r->is_empty()) {
5039 assert(!r->isHumongous(), "H regions should not be empty.");
5040 _n++;
5041 }
5042 return false;
5043 }
5044 int res() { return (int) _n; }
5045 };
5046
5047 size_t G1CollectedHeap::count_free_regions() {
5048 RegionCounter rc;
5049 heap_region_iterate(&rc);
5050 size_t n = rc.res();
5051 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5052 n--;
5053 return n;
5054 }
5055
5056 size_t G1CollectedHeap::count_free_regions_list() {
5057 size_t n = 0;
5058 size_t o = 0;
5059 ZF_mon->lock_without_safepoint_check();
5060 HeapRegion* cur = _free_region_list;
5061 while (cur != NULL) {
5062 cur = cur->next_from_free_list();
5063 n++;
5064 }
5065 size_t m = unclean_region_list_length();
5066 ZF_mon->unlock();
5067 return n + m;
5068 }
5069
5070 bool G1CollectedHeap::should_set_young_locked() {
5071 assert(heap_lock_held_for_gc(),
5072 "the heap lock should already be held by or for this thread");
5073 return (g1_policy()->in_young_gc_mode() &&
5074 g1_policy()->should_add_next_region_to_young_list());
5075 }
5076
5077 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5078 assert(heap_lock_held_for_gc(),
5079 "the heap lock should already be held by or for this thread");
5080 _young_list->push_region(hr);
5081 g1_policy()->set_region_short_lived(hr);
5082 }
5083
5084 class NoYoungRegionsClosure: public HeapRegionClosure {
5085 private:
5086 bool _success;
5087 public:
5088 NoYoungRegionsClosure() : _success(true) { }
5089 bool doHeapRegion(HeapRegion* r) {
5090 if (r->is_young()) {
5091 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5092 r->bottom(), r->end());
5093 _success = false;
5094 }
5095 return false;
5096 }
5097 bool success() { return _success; }
5098 };
5099
5100 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5101 bool ret = _young_list->check_list_empty(check_sample);
5102
5103 if (check_heap) {
5104 NoYoungRegionsClosure closure;
5105 heap_region_iterate(&closure);
5106 ret = ret && closure.success();
5107 }
5108
5109 return ret;
5110 }
5111
5112 void G1CollectedHeap::empty_young_list() {
5113 assert(heap_lock_held_for_gc(),
5114 "the heap lock should already be held by or for this thread");
5115 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5116
5117 _young_list->empty_list();
5118 }
5119
5120 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5121 bool no_allocs = true;
5122 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5123 HeapRegion* r = _gc_alloc_regions[ap];
5124 no_allocs = r == NULL || r->saved_mark_at_top();
5125 }
5126 return no_allocs;
5127 }
5128
5129 void G1CollectedHeap::retire_all_alloc_regions() {
5130 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5131 HeapRegion* r = _gc_alloc_regions[ap];
5132 if (r != NULL) {
5133 // Check for aliases.
5134 bool has_processed_alias = false;
5135 for (int i = 0; i < ap; ++i) {
5136 if (_gc_alloc_regions[i] == r) {
5137 has_processed_alias = true;
5138 break;
5139 }
5140 }
5141 if (!has_processed_alias) {
5142 retire_alloc_region(r, false /* par */);
5143 }
5144 }
5145 }
5146 }
5147
5148
5149 // Done at the start of full GC.
5150 void G1CollectedHeap::tear_down_region_lists() {
5151 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5152 while (pop_unclean_region_list_locked() != NULL) ;
5153 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5154 "Postconditions of loop.");
5155 while (pop_free_region_list_locked() != NULL) ;
5156 assert(_free_region_list == NULL, "Postcondition of loop.");
5157 if (_free_region_list_size != 0) {
5158 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5159 print_on(gclog_or_tty, true /* extended */);
5160 }
5161 assert(_free_region_list_size == 0, "Postconditions of loop.");
5162 }
5163
5164
5165 class RegionResetter: public HeapRegionClosure {
5166 G1CollectedHeap* _g1;
5167 int _n;
5168 public:
5169 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5170 bool doHeapRegion(HeapRegion* r) {
5171 if (r->continuesHumongous()) return false;
5172 if (r->top() > r->bottom()) {
5173 if (r->top() < r->end()) {
5174 Copy::fill_to_words(r->top(),
5175 pointer_delta(r->end(), r->top()));
5176 }
5177 r->set_zero_fill_allocated();
5178 } else {
5179 assert(r->is_empty(), "tautology");
5180 _n++;
5181 switch (r->zero_fill_state()) {
5182 case HeapRegion::NotZeroFilled:
5183 case HeapRegion::ZeroFilling:
5184 _g1->put_region_on_unclean_list_locked(r);
5185 break;
5186 case HeapRegion::Allocated:
5187 r->set_zero_fill_complete();
5188 // no break; go on to put on free list.
5189 case HeapRegion::ZeroFilled:
5190 _g1->put_free_region_on_list_locked(r);
5191 break;
5192 }
5193 }
5194 return false;
5195 }
5196
5197 int getFreeRegionCount() {return _n;}
5198 };
5199
5200 // Done at the end of full GC.
5201 void G1CollectedHeap::rebuild_region_lists() {
5202 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5203 // This needs to go at the end of the full GC.
5204 RegionResetter rs;
5205 heap_region_iterate(&rs);
5206 _free_regions = rs.getFreeRegionCount();
5207 // Tell the ZF thread it may have work to do.
5208 if (should_zf()) ZF_mon->notify_all();
5209 }
5210
5211 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5212 G1CollectedHeap* _g1;
5213 int _n;
5214 public:
5215 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5216 bool doHeapRegion(HeapRegion* r) {
5217 if (r->continuesHumongous()) return false;
5218 if (r->top() > r->bottom()) {
5219 // There are assertions in "set_zero_fill_needed()" below that
5220 // require top() == bottom(), so this is technically illegal.
5221 // We'll skirt the law here, by making that true temporarily.
5222 DEBUG_ONLY(HeapWord* save_top = r->top();
5223 r->set_top(r->bottom()));
5224 r->set_zero_fill_needed();
5225 DEBUG_ONLY(r->set_top(save_top));
5226 }
5227 return false;
5228 }
5229 };
5230
5231 // Done at the start of full GC.
5232 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5233 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5234 // This needs to go at the end of the full GC.
5235 UsedRegionsNeedZeroFillSetter rs;
5236 heap_region_iterate(&rs);
5237 }
5238
5239 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5240 _refine_cte_cl->set_concurrent(concurrent);
5241 }
5242
5243 #ifndef PRODUCT
5244
5245 class PrintHeapRegionClosure: public HeapRegionClosure {
5246 public:
5247 bool doHeapRegion(HeapRegion *r) {
5248 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5249 if (r != NULL) {
5250 if (r->is_on_free_list())
5251 gclog_or_tty->print("Free ");
5252 if (r->is_young())
5253 gclog_or_tty->print("Young ");
5254 if (r->isHumongous())
5255 gclog_or_tty->print("Is Humongous ");
5256 r->print();
5257 }
5258 return false;
5259 }
5260 };
5261
5262 class SortHeapRegionClosure : public HeapRegionClosure {
5263 size_t young_regions,free_regions, unclean_regions;
5264 size_t hum_regions, count;
5265 size_t unaccounted, cur_unclean, cur_alloc;
5266 size_t total_free;
5267 HeapRegion* cur;
5268 public:
5269 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5270 free_regions(0), unclean_regions(0),
5271 hum_regions(0),
5272 count(0), unaccounted(0),
5273 cur_alloc(0), total_free(0)
5274 {}
5275 bool doHeapRegion(HeapRegion *r) {
5276 count++;
5277 if (r->is_on_free_list()) free_regions++;
5278 else if (r->is_on_unclean_list()) unclean_regions++;
5279 else if (r->isHumongous()) hum_regions++;
5280 else if (r->is_young()) young_regions++;
5281 else if (r == cur) cur_alloc++;
5282 else unaccounted++;
5283 return false;
5284 }
5285 void print() {
5286 total_free = free_regions + unclean_regions;
5287 gclog_or_tty->print("%d regions\n", count);
5288 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5289 total_free, free_regions, unclean_regions);
5290 gclog_or_tty->print("%d humongous %d young\n",
5291 hum_regions, young_regions);
5292 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5293 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5294 }
5295 };
5296
5297 void G1CollectedHeap::print_region_counts() {
5298 SortHeapRegionClosure sc(_cur_alloc_region);
5299 PrintHeapRegionClosure cl;
5300 heap_region_iterate(&cl);
5301 heap_region_iterate(&sc);
5302 sc.print();
5303 print_region_accounting_info();
5304 };
5305
5306 bool G1CollectedHeap::regions_accounted_for() {
5307 // TODO: regions accounting for young/survivor/tenured
5308 return true;
5309 }
5310
5311 bool G1CollectedHeap::print_region_accounting_info() {
5312 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5313 free_regions(),
5314 count_free_regions(), count_free_regions_list(),
5315 _free_region_list_size, _unclean_region_list.sz());
5316 gclog_or_tty->print_cr("cur_alloc: %d.",
5317 (_cur_alloc_region == NULL ? 0 : 1));
5318 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5319
5320 // TODO: check regions accounting for young/survivor/tenured
5321 return true;
5322 }
5323
5324 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5325 HeapRegion* hr = heap_region_containing(p);
5326 if (hr == NULL) {
5327 return is_in_permanent(p);
5328 } else {
5329 return hr->is_in(p);
5330 }
5331 }
5332 #endif // !PRODUCT
5333
5334 void G1CollectedHeap::g1_unimplemented() {
5335 // Unimplemented();
5336 }