Thu, 11 Feb 2010 15:52:19 -0800
6923991: G1: improve scalability of RSet scanning
Summary: Implemented block-based work stealing. Moved copying during the rset scanning phase to the main copying phase. Made the size of rset table depend on the region size.
Reviewed-by: apetrusenko, tonyp
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectedHeap.cpp.incl"
28 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
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 SCAN_ONLY_VERBOSE 0
34 // CURRENT STATUS
35 // This file is under construction. Search for "FIXME".
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.)
45 // Local to this file.
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 _g1rs->concurrentRefineOneCard(card_ptr, worker_i);
60 if (_concurrent && _sts->should_yield()) {
61 // Caller will actually yield.
62 return false;
63 }
64 // Otherwise, we finished successfully; return true.
65 return true;
66 }
67 void set_concurrent(bool b) { _concurrent = b; }
68 };
71 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
72 int _calls;
73 G1CollectedHeap* _g1h;
74 CardTableModRefBS* _ctbs;
75 int _histo[256];
76 public:
77 ClearLoggedCardTableEntryClosure() :
78 _calls(0)
79 {
80 _g1h = G1CollectedHeap::heap();
81 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
82 for (int i = 0; i < 256; i++) _histo[i] = 0;
83 }
84 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
85 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
86 _calls++;
87 unsigned char* ujb = (unsigned char*)card_ptr;
88 int ind = (int)(*ujb);
89 _histo[ind]++;
90 *card_ptr = -1;
91 }
92 return true;
93 }
94 int calls() { return _calls; }
95 void print_histo() {
96 gclog_or_tty->print_cr("Card table value histogram:");
97 for (int i = 0; i < 256; i++) {
98 if (_histo[i] != 0) {
99 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
100 }
101 }
102 }
103 };
105 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
106 int _calls;
107 G1CollectedHeap* _g1h;
108 CardTableModRefBS* _ctbs;
109 public:
110 RedirtyLoggedCardTableEntryClosure() :
111 _calls(0)
112 {
113 _g1h = G1CollectedHeap::heap();
114 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
115 }
116 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
117 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
118 _calls++;
119 *card_ptr = 0;
120 }
121 return true;
122 }
123 int calls() { return _calls; }
124 };
126 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
127 public:
128 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
129 *card_ptr = CardTableModRefBS::dirty_card_val();
130 return true;
131 }
132 };
134 YoungList::YoungList(G1CollectedHeap* g1h)
135 : _g1h(g1h), _head(NULL),
136 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
137 _length(0), _scan_only_length(0),
138 _last_sampled_rs_lengths(0),
139 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
140 {
141 guarantee( check_list_empty(false), "just making sure..." );
142 }
144 void YoungList::push_region(HeapRegion *hr) {
145 assert(!hr->is_young(), "should not already be young");
146 assert(hr->get_next_young_region() == NULL, "cause it should!");
148 hr->set_next_young_region(_head);
149 _head = hr;
151 hr->set_young();
152 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
153 ++_length;
154 }
156 void YoungList::add_survivor_region(HeapRegion* hr) {
157 assert(hr->is_survivor(), "should be flagged as survivor region");
158 assert(hr->get_next_young_region() == NULL, "cause it should!");
160 hr->set_next_young_region(_survivor_head);
161 if (_survivor_head == NULL) {
162 _survivor_tail = hr;
163 }
164 _survivor_head = hr;
166 ++_survivor_length;
167 }
169 HeapRegion* YoungList::pop_region() {
170 while (_head != NULL) {
171 assert( length() > 0, "list should not be empty" );
172 HeapRegion* ret = _head;
173 _head = ret->get_next_young_region();
174 ret->set_next_young_region(NULL);
175 --_length;
176 assert(ret->is_young(), "region should be very young");
178 // Replace 'Survivor' region type with 'Young'. So the region will
179 // be treated as a young region and will not be 'confused' with
180 // newly created survivor regions.
181 if (ret->is_survivor()) {
182 ret->set_young();
183 }
185 if (!ret->is_scan_only()) {
186 return ret;
187 }
189 // scan-only, we'll add it to the scan-only list
190 if (_scan_only_tail == NULL) {
191 guarantee( _scan_only_head == NULL, "invariant" );
193 _scan_only_head = ret;
194 _curr_scan_only = ret;
195 } else {
196 guarantee( _scan_only_head != NULL, "invariant" );
197 _scan_only_tail->set_next_young_region(ret);
198 }
199 guarantee( ret->get_next_young_region() == NULL, "invariant" );
200 _scan_only_tail = ret;
202 // no need to be tagged as scan-only any more
203 ret->set_young();
205 ++_scan_only_length;
206 }
207 assert( length() == 0, "list should be empty" );
208 return NULL;
209 }
211 void YoungList::empty_list(HeapRegion* list) {
212 while (list != NULL) {
213 HeapRegion* next = list->get_next_young_region();
214 list->set_next_young_region(NULL);
215 list->uninstall_surv_rate_group();
216 list->set_not_young();
217 list = next;
218 }
219 }
221 void YoungList::empty_list() {
222 assert(check_list_well_formed(), "young list should be well formed");
224 empty_list(_head);
225 _head = NULL;
226 _length = 0;
228 empty_list(_scan_only_head);
229 _scan_only_head = NULL;
230 _scan_only_tail = NULL;
231 _scan_only_length = 0;
232 _curr_scan_only = NULL;
234 empty_list(_survivor_head);
235 _survivor_head = NULL;
236 _survivor_tail = NULL;
237 _survivor_length = 0;
239 _last_sampled_rs_lengths = 0;
241 assert(check_list_empty(false), "just making sure...");
242 }
244 bool YoungList::check_list_well_formed() {
245 bool ret = true;
247 size_t length = 0;
248 HeapRegion* curr = _head;
249 HeapRegion* last = NULL;
250 while (curr != NULL) {
251 if (!curr->is_young() || curr->is_scan_only()) {
252 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
253 "incorrectly tagged (%d, %d)",
254 curr->bottom(), curr->end(),
255 curr->is_young(), curr->is_scan_only());
256 ret = false;
257 }
258 ++length;
259 last = curr;
260 curr = curr->get_next_young_region();
261 }
262 ret = ret && (length == _length);
264 if (!ret) {
265 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
266 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
267 length, _length);
268 }
270 bool scan_only_ret = true;
271 length = 0;
272 curr = _scan_only_head;
273 last = NULL;
274 while (curr != NULL) {
275 if (!curr->is_young() || curr->is_scan_only()) {
276 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
277 "incorrectly tagged (%d, %d)",
278 curr->bottom(), curr->end(),
279 curr->is_young(), curr->is_scan_only());
280 scan_only_ret = false;
281 }
282 ++length;
283 last = curr;
284 curr = curr->get_next_young_region();
285 }
286 scan_only_ret = scan_only_ret && (length == _scan_only_length);
288 if ( (last != _scan_only_tail) ||
289 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
290 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
291 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
292 scan_only_ret = false;
293 }
295 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
296 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
297 scan_only_ret = false;
298 }
300 if (!scan_only_ret) {
301 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
302 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
303 length, _scan_only_length);
304 }
306 return ret && scan_only_ret;
307 }
309 bool YoungList::check_list_empty(bool ignore_scan_only_list,
310 bool check_sample) {
311 bool ret = true;
313 if (_length != 0) {
314 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
315 _length);
316 ret = false;
317 }
318 if (check_sample && _last_sampled_rs_lengths != 0) {
319 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
320 ret = false;
321 }
322 if (_head != NULL) {
323 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
324 ret = false;
325 }
326 if (!ret) {
327 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
328 }
330 if (ignore_scan_only_list)
331 return ret;
333 bool scan_only_ret = true;
334 if (_scan_only_length != 0) {
335 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
336 _scan_only_length);
337 scan_only_ret = false;
338 }
339 if (_scan_only_head != NULL) {
340 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
341 scan_only_ret = false;
342 }
343 if (_scan_only_tail != NULL) {
344 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
345 scan_only_ret = false;
346 }
347 if (!scan_only_ret) {
348 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
349 }
351 return ret && scan_only_ret;
352 }
354 void
355 YoungList::rs_length_sampling_init() {
356 _sampled_rs_lengths = 0;
357 _curr = _head;
358 }
360 bool
361 YoungList::rs_length_sampling_more() {
362 return _curr != NULL;
363 }
365 void
366 YoungList::rs_length_sampling_next() {
367 assert( _curr != NULL, "invariant" );
368 _sampled_rs_lengths += _curr->rem_set()->occupied();
369 _curr = _curr->get_next_young_region();
370 if (_curr == NULL) {
371 _last_sampled_rs_lengths = _sampled_rs_lengths;
372 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
373 }
374 }
376 void
377 YoungList::reset_auxilary_lists() {
378 // We could have just "moved" the scan-only list to the young list.
379 // However, the scan-only list is ordered according to the region
380 // age in descending order, so, by moving one entry at a time, we
381 // ensure that it is recreated in ascending order.
383 guarantee( is_empty(), "young list should be empty" );
384 assert(check_list_well_formed(), "young list should be well formed");
386 // Add survivor regions to SurvRateGroup.
387 _g1h->g1_policy()->note_start_adding_survivor_regions();
388 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
389 for (HeapRegion* curr = _survivor_head;
390 curr != NULL;
391 curr = curr->get_next_young_region()) {
392 _g1h->g1_policy()->set_region_survivors(curr);
393 }
394 _g1h->g1_policy()->note_stop_adding_survivor_regions();
396 if (_survivor_head != NULL) {
397 _head = _survivor_head;
398 _length = _survivor_length + _scan_only_length;
399 _survivor_tail->set_next_young_region(_scan_only_head);
400 } else {
401 _head = _scan_only_head;
402 _length = _scan_only_length;
403 }
405 for (HeapRegion* curr = _scan_only_head;
406 curr != NULL;
407 curr = curr->get_next_young_region()) {
408 curr->recalculate_age_in_surv_rate_group();
409 }
410 _scan_only_head = NULL;
411 _scan_only_tail = NULL;
412 _scan_only_length = 0;
413 _curr_scan_only = NULL;
415 _survivor_head = NULL;
416 _survivor_tail = NULL;
417 _survivor_length = 0;
418 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
420 assert(check_list_well_formed(), "young list should be well formed");
421 }
423 void YoungList::print() {
424 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
425 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
427 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
428 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
429 HeapRegion *curr = lists[list];
430 if (curr == NULL)
431 gclog_or_tty->print_cr(" empty");
432 while (curr != NULL) {
433 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
434 "age: %4d, y: %d, s-o: %d, surv: %d",
435 curr->bottom(), curr->end(),
436 curr->top(),
437 curr->prev_top_at_mark_start(),
438 curr->next_top_at_mark_start(),
439 curr->top_at_conc_mark_count(),
440 curr->age_in_surv_rate_group_cond(),
441 curr->is_young(),
442 curr->is_scan_only(),
443 curr->is_survivor());
444 curr = curr->get_next_young_region();
445 }
446 }
448 gclog_or_tty->print_cr("");
449 }
451 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
452 {
453 // Claim the right to put the region on the dirty cards region list
454 // by installing a self pointer.
455 HeapRegion* next = hr->get_next_dirty_cards_region();
456 if (next == NULL) {
457 HeapRegion* res = (HeapRegion*)
458 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
459 NULL);
460 if (res == NULL) {
461 HeapRegion* head;
462 do {
463 // Put the region to the dirty cards region list.
464 head = _dirty_cards_region_list;
465 next = (HeapRegion*)
466 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
467 if (next == head) {
468 assert(hr->get_next_dirty_cards_region() == hr,
469 "hr->get_next_dirty_cards_region() != hr");
470 if (next == NULL) {
471 // The last region in the list points to itself.
472 hr->set_next_dirty_cards_region(hr);
473 } else {
474 hr->set_next_dirty_cards_region(next);
475 }
476 }
477 } while (next != head);
478 }
479 }
480 }
482 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
483 {
484 HeapRegion* head;
485 HeapRegion* hr;
486 do {
487 head = _dirty_cards_region_list;
488 if (head == NULL) {
489 return NULL;
490 }
491 HeapRegion* new_head = head->get_next_dirty_cards_region();
492 if (head == new_head) {
493 // The last region.
494 new_head = NULL;
495 }
496 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
497 head);
498 } while (hr != head);
499 assert(hr != NULL, "invariant");
500 hr->set_next_dirty_cards_region(NULL);
501 return hr;
502 }
504 void G1CollectedHeap::stop_conc_gc_threads() {
505 _cg1r->stop();
506 _czft->stop();
507 _cmThread->stop();
508 }
511 void G1CollectedHeap::check_ct_logs_at_safepoint() {
512 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
513 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
515 // Count the dirty cards at the start.
516 CountNonCleanMemRegionClosure count1(this);
517 ct_bs->mod_card_iterate(&count1);
518 int orig_count = count1.n();
520 // First clear the logged cards.
521 ClearLoggedCardTableEntryClosure clear;
522 dcqs.set_closure(&clear);
523 dcqs.apply_closure_to_all_completed_buffers();
524 dcqs.iterate_closure_all_threads(false);
525 clear.print_histo();
527 // Now ensure that there's no dirty cards.
528 CountNonCleanMemRegionClosure count2(this);
529 ct_bs->mod_card_iterate(&count2);
530 if (count2.n() != 0) {
531 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
532 count2.n(), orig_count);
533 }
534 guarantee(count2.n() == 0, "Card table should be clean.");
536 RedirtyLoggedCardTableEntryClosure redirty;
537 JavaThread::dirty_card_queue_set().set_closure(&redirty);
538 dcqs.apply_closure_to_all_completed_buffers();
539 dcqs.iterate_closure_all_threads(false);
540 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
541 clear.calls(), orig_count);
542 guarantee(redirty.calls() == clear.calls(),
543 "Or else mechanism is broken.");
545 CountNonCleanMemRegionClosure count3(this);
546 ct_bs->mod_card_iterate(&count3);
547 if (count3.n() != orig_count) {
548 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
549 orig_count, count3.n());
550 guarantee(count3.n() >= orig_count, "Should have restored them all.");
551 }
553 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
554 }
556 // Private class members.
558 G1CollectedHeap* G1CollectedHeap::_g1h;
560 // Private methods.
562 // Finds a HeapRegion that can be used to allocate a given size of block.
565 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
566 bool do_expand,
567 bool zero_filled) {
568 ConcurrentZFThread::note_region_alloc();
569 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
570 if (res == NULL && do_expand) {
571 expand(word_size * HeapWordSize);
572 res = alloc_free_region_from_lists(zero_filled);
573 assert(res == NULL ||
574 (!res->isHumongous() &&
575 (!zero_filled ||
576 res->zero_fill_state() == HeapRegion::Allocated)),
577 "Alloc Regions must be zero filled (and non-H)");
578 }
579 if (res != NULL && res->is_empty()) _free_regions--;
580 assert(res == NULL ||
581 (!res->isHumongous() &&
582 (!zero_filled ||
583 res->zero_fill_state() == HeapRegion::Allocated)),
584 "Non-young alloc Regions must be zero filled (and non-H)");
586 if (G1PrintRegions) {
587 if (res != NULL) {
588 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
589 "top "PTR_FORMAT,
590 res->hrs_index(), res->bottom(), res->end(), res->top());
591 }
592 }
594 return res;
595 }
597 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
598 size_t word_size,
599 bool zero_filled) {
600 HeapRegion* alloc_region = NULL;
601 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
602 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
603 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
604 alloc_region->set_survivor();
605 }
606 ++_gc_alloc_region_counts[purpose];
607 } else {
608 g1_policy()->note_alloc_region_limit_reached(purpose);
609 }
610 return alloc_region;
611 }
613 // If could fit into free regions w/o expansion, try.
614 // Otherwise, if can expand, do so.
615 // Otherwise, if using ex regions might help, try with ex given back.
616 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
617 assert(regions_accounted_for(), "Region leakage!");
619 // We can't allocate H regions while cleanupComplete is running, since
620 // some of the regions we find to be empty might not yet be added to the
621 // unclean list. (If we're already at a safepoint, this call is
622 // unnecessary, not to mention wrong.)
623 if (!SafepointSynchronize::is_at_safepoint())
624 wait_for_cleanup_complete();
626 size_t num_regions =
627 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
629 // Special case if < one region???
631 // Remember the ft size.
632 size_t x_size = expansion_regions();
634 HeapWord* res = NULL;
635 bool eliminated_allocated_from_lists = false;
637 // Can the allocation potentially fit in the free regions?
638 if (free_regions() >= num_regions) {
639 res = _hrs->obj_allocate(word_size);
640 }
641 if (res == NULL) {
642 // Try expansion.
643 size_t fs = _hrs->free_suffix();
644 if (fs + x_size >= num_regions) {
645 expand((num_regions - fs) * HeapRegion::GrainBytes);
646 res = _hrs->obj_allocate(word_size);
647 assert(res != NULL, "This should have worked.");
648 } else {
649 // Expansion won't help. Are there enough free regions if we get rid
650 // of reservations?
651 size_t avail = free_regions();
652 if (avail >= num_regions) {
653 res = _hrs->obj_allocate(word_size);
654 if (res != NULL) {
655 remove_allocated_regions_from_lists();
656 eliminated_allocated_from_lists = true;
657 }
658 }
659 }
660 }
661 if (res != NULL) {
662 // Increment by the number of regions allocated.
663 // FIXME: Assumes regions all of size GrainBytes.
664 #ifndef PRODUCT
665 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
666 HeapRegion::GrainWords));
667 #endif
668 if (!eliminated_allocated_from_lists)
669 remove_allocated_regions_from_lists();
670 _summary_bytes_used += word_size * HeapWordSize;
671 _free_regions -= num_regions;
672 _num_humongous_regions += (int) num_regions;
673 }
674 assert(regions_accounted_for(), "Region Leakage");
675 return res;
676 }
678 HeapWord*
679 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
680 bool permit_collection_pause) {
681 HeapWord* res = NULL;
682 HeapRegion* allocated_young_region = NULL;
684 assert( SafepointSynchronize::is_at_safepoint() ||
685 Heap_lock->owned_by_self(), "pre condition of the call" );
687 if (isHumongous(word_size)) {
688 // Allocation of a humongous object can, in a sense, complete a
689 // partial region, if the previous alloc was also humongous, and
690 // caused the test below to succeed.
691 if (permit_collection_pause)
692 do_collection_pause_if_appropriate(word_size);
693 res = humongousObjAllocate(word_size);
694 assert(_cur_alloc_region == NULL
695 || !_cur_alloc_region->isHumongous(),
696 "Prevent a regression of this bug.");
698 } else {
699 // We may have concurrent cleanup working at the time. Wait for it
700 // to complete. In the future we would probably want to make the
701 // concurrent cleanup truly concurrent by decoupling it from the
702 // allocation.
703 if (!SafepointSynchronize::is_at_safepoint())
704 wait_for_cleanup_complete();
705 // If we do a collection pause, this will be reset to a non-NULL
706 // value. If we don't, nulling here ensures that we allocate a new
707 // region below.
708 if (_cur_alloc_region != NULL) {
709 // We're finished with the _cur_alloc_region.
710 _summary_bytes_used += _cur_alloc_region->used();
711 _cur_alloc_region = NULL;
712 }
713 assert(_cur_alloc_region == NULL, "Invariant.");
714 // Completion of a heap region is perhaps a good point at which to do
715 // a collection pause.
716 if (permit_collection_pause)
717 do_collection_pause_if_appropriate(word_size);
718 // Make sure we have an allocation region available.
719 if (_cur_alloc_region == NULL) {
720 if (!SafepointSynchronize::is_at_safepoint())
721 wait_for_cleanup_complete();
722 bool next_is_young = should_set_young_locked();
723 // If the next region is not young, make sure it's zero-filled.
724 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
725 if (_cur_alloc_region != NULL) {
726 _summary_bytes_used -= _cur_alloc_region->used();
727 if (next_is_young) {
728 set_region_short_lived_locked(_cur_alloc_region);
729 allocated_young_region = _cur_alloc_region;
730 }
731 }
732 }
733 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
734 "Prevent a regression of this bug.");
736 // Now retry the allocation.
737 if (_cur_alloc_region != NULL) {
738 res = _cur_alloc_region->allocate(word_size);
739 }
740 }
742 // NOTE: fails frequently in PRT
743 assert(regions_accounted_for(), "Region leakage!");
745 if (res != NULL) {
746 if (!SafepointSynchronize::is_at_safepoint()) {
747 assert( permit_collection_pause, "invariant" );
748 assert( Heap_lock->owned_by_self(), "invariant" );
749 Heap_lock->unlock();
750 }
752 if (allocated_young_region != NULL) {
753 HeapRegion* hr = allocated_young_region;
754 HeapWord* bottom = hr->bottom();
755 HeapWord* end = hr->end();
756 MemRegion mr(bottom, end);
757 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
758 }
759 }
761 assert( SafepointSynchronize::is_at_safepoint() ||
762 (res == NULL && Heap_lock->owned_by_self()) ||
763 (res != NULL && !Heap_lock->owned_by_self()),
764 "post condition of the call" );
766 return res;
767 }
769 HeapWord*
770 G1CollectedHeap::mem_allocate(size_t word_size,
771 bool is_noref,
772 bool is_tlab,
773 bool* gc_overhead_limit_was_exceeded) {
774 debug_only(check_for_valid_allocation_state());
775 assert(no_gc_in_progress(), "Allocation during gc not allowed");
776 HeapWord* result = NULL;
778 // Loop until the allocation is satisified,
779 // or unsatisfied after GC.
780 for (int try_count = 1; /* return or throw */; try_count += 1) {
781 int gc_count_before;
782 {
783 Heap_lock->lock();
784 result = attempt_allocation(word_size);
785 if (result != NULL) {
786 // attempt_allocation should have unlocked the heap lock
787 assert(is_in(result), "result not in heap");
788 return result;
789 }
790 // Read the gc count while the heap lock is held.
791 gc_count_before = SharedHeap::heap()->total_collections();
792 Heap_lock->unlock();
793 }
795 // Create the garbage collection operation...
796 VM_G1CollectForAllocation op(word_size,
797 gc_count_before);
799 // ...and get the VM thread to execute it.
800 VMThread::execute(&op);
801 if (op.prologue_succeeded()) {
802 result = op.result();
803 assert(result == NULL || is_in(result), "result not in heap");
804 return result;
805 }
807 // Give a warning if we seem to be looping forever.
808 if ((QueuedAllocationWarningCount > 0) &&
809 (try_count % QueuedAllocationWarningCount == 0)) {
810 warning("G1CollectedHeap::mem_allocate_work retries %d times",
811 try_count);
812 }
813 }
814 }
816 void G1CollectedHeap::abandon_cur_alloc_region() {
817 if (_cur_alloc_region != NULL) {
818 // We're finished with the _cur_alloc_region.
819 if (_cur_alloc_region->is_empty()) {
820 _free_regions++;
821 free_region(_cur_alloc_region);
822 } else {
823 _summary_bytes_used += _cur_alloc_region->used();
824 }
825 _cur_alloc_region = NULL;
826 }
827 }
829 void G1CollectedHeap::abandon_gc_alloc_regions() {
830 // first, make sure that the GC alloc region list is empty (it should!)
831 assert(_gc_alloc_region_list == NULL, "invariant");
832 release_gc_alloc_regions(true /* totally */);
833 }
835 class PostMCRemSetClearClosure: public HeapRegionClosure {
836 ModRefBarrierSet* _mr_bs;
837 public:
838 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
839 bool doHeapRegion(HeapRegion* r) {
840 r->reset_gc_time_stamp();
841 if (r->continuesHumongous())
842 return false;
843 HeapRegionRemSet* hrrs = r->rem_set();
844 if (hrrs != NULL) hrrs->clear();
845 // You might think here that we could clear just the cards
846 // corresponding to the used region. But no: if we leave a dirty card
847 // in a region we might allocate into, then it would prevent that card
848 // from being enqueued, and cause it to be missed.
849 // Re: the performance cost: we shouldn't be doing full GC anyway!
850 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
851 return false;
852 }
853 };
856 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
857 ModRefBarrierSet* _mr_bs;
858 public:
859 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
860 bool doHeapRegion(HeapRegion* r) {
861 if (r->continuesHumongous()) return false;
862 if (r->used_region().word_size() != 0) {
863 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
864 }
865 return false;
866 }
867 };
869 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
870 G1CollectedHeap* _g1h;
871 UpdateRSOopClosure _cl;
872 int _worker_i;
873 public:
874 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
875 _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
876 _worker_i(worker_i),
877 _g1h(g1)
878 { }
879 bool doHeapRegion(HeapRegion* r) {
880 if (!r->continuesHumongous()) {
881 _cl.set_from(r);
882 r->oop_iterate(&_cl);
883 }
884 return false;
885 }
886 };
888 class ParRebuildRSTask: public AbstractGangTask {
889 G1CollectedHeap* _g1;
890 public:
891 ParRebuildRSTask(G1CollectedHeap* g1)
892 : AbstractGangTask("ParRebuildRSTask"),
893 _g1(g1)
894 { }
896 void work(int i) {
897 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
898 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
899 HeapRegion::RebuildRSClaimValue);
900 }
901 };
903 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
904 size_t word_size) {
905 ResourceMark rm;
907 if (PrintHeapAtGC) {
908 Universe::print_heap_before_gc();
909 }
911 if (full && DisableExplicitGC) {
912 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
913 return;
914 }
916 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
917 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
919 if (GC_locker::is_active()) {
920 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
921 }
923 {
924 IsGCActiveMark x;
926 // Timing
927 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
928 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
929 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
931 TraceMemoryManagerStats tms(true /* fullGC */);
933 double start = os::elapsedTime();
934 g1_policy()->record_full_collection_start();
936 gc_prologue(true);
937 increment_total_collections(true /* full gc */);
939 size_t g1h_prev_used = used();
940 assert(used() == recalculate_used(), "Should be equal");
942 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
943 HandleMark hm; // Discard invalid handles created during verification
944 prepare_for_verify();
945 gclog_or_tty->print(" VerifyBeforeGC:");
946 Universe::verify(true);
947 }
948 assert(regions_accounted_for(), "Region leakage!");
950 COMPILER2_PRESENT(DerivedPointerTable::clear());
952 // We want to discover references, but not process them yet.
953 // This mode is disabled in
954 // instanceRefKlass::process_discovered_references if the
955 // generation does some collection work, or
956 // instanceRefKlass::enqueue_discovered_references if the
957 // generation returns without doing any work.
958 ref_processor()->disable_discovery();
959 ref_processor()->abandon_partial_discovery();
960 ref_processor()->verify_no_references_recorded();
962 // Abandon current iterations of concurrent marking and concurrent
963 // refinement, if any are in progress.
964 concurrent_mark()->abort();
966 // Make sure we'll choose a new allocation region afterwards.
967 abandon_cur_alloc_region();
968 abandon_gc_alloc_regions();
969 assert(_cur_alloc_region == NULL, "Invariant.");
970 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
971 tear_down_region_lists();
972 set_used_regions_to_need_zero_fill();
973 if (g1_policy()->in_young_gc_mode()) {
974 empty_young_list();
975 g1_policy()->set_full_young_gcs(true);
976 }
978 // Temporarily make reference _discovery_ single threaded (non-MT).
979 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
981 // Temporarily make refs discovery atomic
982 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
984 // Temporarily clear _is_alive_non_header
985 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
987 ref_processor()->enable_discovery();
988 ref_processor()->setup_policy(clear_all_soft_refs);
990 // Do collection work
991 {
992 HandleMark hm; // Discard invalid handles created during gc
993 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
994 }
995 // Because freeing humongous regions may have added some unclean
996 // regions, it is necessary to tear down again before rebuilding.
997 tear_down_region_lists();
998 rebuild_region_lists();
1000 _summary_bytes_used = recalculate_used();
1002 ref_processor()->enqueue_discovered_references();
1004 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1006 MemoryService::track_memory_usage();
1008 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1009 HandleMark hm; // Discard invalid handles created during verification
1010 gclog_or_tty->print(" VerifyAfterGC:");
1011 prepare_for_verify();
1012 Universe::verify(false);
1013 }
1014 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1016 reset_gc_time_stamp();
1017 // Since everything potentially moved, we will clear all remembered
1018 // sets, and clear all cards. Later we will rebuild remebered
1019 // sets. We will also reset the GC time stamps of the regions.
1020 PostMCRemSetClearClosure rs_clear(mr_bs());
1021 heap_region_iterate(&rs_clear);
1023 // Resize the heap if necessary.
1024 resize_if_necessary_after_full_collection(full ? 0 : word_size);
1026 if (_cg1r->use_cache()) {
1027 _cg1r->clear_and_record_card_counts();
1028 _cg1r->clear_hot_cache();
1029 }
1031 // Rebuild remembered sets of all regions.
1032 if (ParallelGCThreads > 0) {
1033 ParRebuildRSTask rebuild_rs_task(this);
1034 assert(check_heap_region_claim_values(
1035 HeapRegion::InitialClaimValue), "sanity check");
1036 set_par_threads(workers()->total_workers());
1037 workers()->run_task(&rebuild_rs_task);
1038 set_par_threads(0);
1039 assert(check_heap_region_claim_values(
1040 HeapRegion::RebuildRSClaimValue), "sanity check");
1041 reset_heap_region_claim_values();
1042 } else {
1043 RebuildRSOutOfRegionClosure rebuild_rs(this);
1044 heap_region_iterate(&rebuild_rs);
1045 }
1047 if (PrintGC) {
1048 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1049 }
1051 if (true) { // FIXME
1052 // Ask the permanent generation to adjust size for full collections
1053 perm()->compute_new_size();
1054 }
1056 double end = os::elapsedTime();
1057 g1_policy()->record_full_collection_end();
1059 #ifdef TRACESPINNING
1060 ParallelTaskTerminator::print_termination_counts();
1061 #endif
1063 gc_epilogue(true);
1065 // Discard all rset updates
1066 JavaThread::dirty_card_queue_set().abandon_logs();
1067 assert(!G1DeferredRSUpdate
1068 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1069 assert(regions_accounted_for(), "Region leakage!");
1070 }
1072 if (g1_policy()->in_young_gc_mode()) {
1073 _young_list->reset_sampled_info();
1074 assert( check_young_list_empty(false, false),
1075 "young list should be empty at this point");
1076 }
1078 if (PrintHeapAtGC) {
1079 Universe::print_heap_after_gc();
1080 }
1081 }
1083 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1084 do_collection(true, clear_all_soft_refs, 0);
1085 }
1087 // This code is mostly copied from TenuredGeneration.
1088 void
1089 G1CollectedHeap::
1090 resize_if_necessary_after_full_collection(size_t word_size) {
1091 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1093 // Include the current allocation, if any, and bytes that will be
1094 // pre-allocated to support collections, as "used".
1095 const size_t used_after_gc = used();
1096 const size_t capacity_after_gc = capacity();
1097 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1099 // We don't have floating point command-line arguments
1100 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1101 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1102 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1103 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1105 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1106 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1108 // Don't shrink less than the initial size.
1109 minimum_desired_capacity =
1110 MAX2(minimum_desired_capacity,
1111 collector_policy()->initial_heap_byte_size());
1112 maximum_desired_capacity =
1113 MAX2(maximum_desired_capacity,
1114 collector_policy()->initial_heap_byte_size());
1116 // We are failing here because minimum_desired_capacity is
1117 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1118 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1120 if (PrintGC && Verbose) {
1121 const double free_percentage = ((double)free_after_gc) / capacity();
1122 gclog_or_tty->print_cr("Computing new size after full GC ");
1123 gclog_or_tty->print_cr(" "
1124 " minimum_free_percentage: %6.2f",
1125 minimum_free_percentage);
1126 gclog_or_tty->print_cr(" "
1127 " maximum_free_percentage: %6.2f",
1128 maximum_free_percentage);
1129 gclog_or_tty->print_cr(" "
1130 " capacity: %6.1fK"
1131 " minimum_desired_capacity: %6.1fK"
1132 " maximum_desired_capacity: %6.1fK",
1133 capacity() / (double) K,
1134 minimum_desired_capacity / (double) K,
1135 maximum_desired_capacity / (double) K);
1136 gclog_or_tty->print_cr(" "
1137 " free_after_gc : %6.1fK"
1138 " used_after_gc : %6.1fK",
1139 free_after_gc / (double) K,
1140 used_after_gc / (double) K);
1141 gclog_or_tty->print_cr(" "
1142 " free_percentage: %6.2f",
1143 free_percentage);
1144 }
1145 if (capacity() < minimum_desired_capacity) {
1146 // Don't expand unless it's significant
1147 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1148 expand(expand_bytes);
1149 if (PrintGC && Verbose) {
1150 gclog_or_tty->print_cr(" expanding:"
1151 " minimum_desired_capacity: %6.1fK"
1152 " expand_bytes: %6.1fK",
1153 minimum_desired_capacity / (double) K,
1154 expand_bytes / (double) K);
1155 }
1157 // No expansion, now see if we want to shrink
1158 } else if (capacity() > maximum_desired_capacity) {
1159 // Capacity too large, compute shrinking size
1160 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1161 shrink(shrink_bytes);
1162 if (PrintGC && Verbose) {
1163 gclog_or_tty->print_cr(" "
1164 " shrinking:"
1165 " initSize: %.1fK"
1166 " maximum_desired_capacity: %.1fK",
1167 collector_policy()->initial_heap_byte_size() / (double) K,
1168 maximum_desired_capacity / (double) K);
1169 gclog_or_tty->print_cr(" "
1170 " shrink_bytes: %.1fK",
1171 shrink_bytes / (double) K);
1172 }
1173 }
1174 }
1177 HeapWord*
1178 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1179 HeapWord* result = NULL;
1181 // In a G1 heap, we're supposed to keep allocation from failing by
1182 // incremental pauses. Therefore, at least for now, we'll favor
1183 // expansion over collection. (This might change in the future if we can
1184 // do something smarter than full collection to satisfy a failed alloc.)
1186 result = expand_and_allocate(word_size);
1187 if (result != NULL) {
1188 assert(is_in(result), "result not in heap");
1189 return result;
1190 }
1192 // OK, I guess we have to try collection.
1194 do_collection(false, false, word_size);
1196 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1198 if (result != NULL) {
1199 assert(is_in(result), "result not in heap");
1200 return result;
1201 }
1203 // Try collecting soft references.
1204 do_collection(false, true, word_size);
1205 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1206 if (result != NULL) {
1207 assert(is_in(result), "result not in heap");
1208 return result;
1209 }
1211 // What else? We might try synchronous finalization later. If the total
1212 // space available is large enough for the allocation, then a more
1213 // complete compaction phase than we've tried so far might be
1214 // appropriate.
1215 return NULL;
1216 }
1218 // Attempting to expand the heap sufficiently
1219 // to support an allocation of the given "word_size". If
1220 // successful, perform the allocation and return the address of the
1221 // allocated block, or else "NULL".
1223 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1224 size_t expand_bytes = word_size * HeapWordSize;
1225 if (expand_bytes < MinHeapDeltaBytes) {
1226 expand_bytes = MinHeapDeltaBytes;
1227 }
1228 expand(expand_bytes);
1229 assert(regions_accounted_for(), "Region leakage!");
1230 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1231 return result;
1232 }
1234 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1235 size_t pre_used = 0;
1236 size_t cleared_h_regions = 0;
1237 size_t freed_regions = 0;
1238 UncleanRegionList local_list;
1239 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1240 freed_regions, &local_list);
1242 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1243 &local_list);
1244 return pre_used;
1245 }
1247 void
1248 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1249 size_t& pre_used,
1250 size_t& cleared_h,
1251 size_t& freed_regions,
1252 UncleanRegionList* list,
1253 bool par) {
1254 assert(!hr->continuesHumongous(), "should have filtered these out");
1255 size_t res = 0;
1256 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1257 !hr->is_young()) {
1258 if (G1PolicyVerbose > 0)
1259 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1260 " during cleanup", hr, hr->used());
1261 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1262 }
1263 }
1265 // FIXME: both this and shrink could probably be more efficient by
1266 // doing one "VirtualSpace::expand_by" call rather than several.
1267 void G1CollectedHeap::expand(size_t expand_bytes) {
1268 size_t old_mem_size = _g1_storage.committed_size();
1269 // We expand by a minimum of 1K.
1270 expand_bytes = MAX2(expand_bytes, (size_t)K);
1271 size_t aligned_expand_bytes =
1272 ReservedSpace::page_align_size_up(expand_bytes);
1273 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1274 HeapRegion::GrainBytes);
1275 expand_bytes = aligned_expand_bytes;
1276 while (expand_bytes > 0) {
1277 HeapWord* base = (HeapWord*)_g1_storage.high();
1278 // Commit more storage.
1279 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1280 if (!successful) {
1281 expand_bytes = 0;
1282 } else {
1283 expand_bytes -= HeapRegion::GrainBytes;
1284 // Expand the committed region.
1285 HeapWord* high = (HeapWord*) _g1_storage.high();
1286 _g1_committed.set_end(high);
1287 // Create a new HeapRegion.
1288 MemRegion mr(base, high);
1289 bool is_zeroed = !_g1_max_committed.contains(base);
1290 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1292 // Now update max_committed if necessary.
1293 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1295 // Add it to the HeapRegionSeq.
1296 _hrs->insert(hr);
1297 // Set the zero-fill state, according to whether it's already
1298 // zeroed.
1299 {
1300 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1301 if (is_zeroed) {
1302 hr->set_zero_fill_complete();
1303 put_free_region_on_list_locked(hr);
1304 } else {
1305 hr->set_zero_fill_needed();
1306 put_region_on_unclean_list_locked(hr);
1307 }
1308 }
1309 _free_regions++;
1310 // And we used up an expansion region to create it.
1311 _expansion_regions--;
1312 // Tell the cardtable about it.
1313 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1314 // And the offset table as well.
1315 _bot_shared->resize(_g1_committed.word_size());
1316 }
1317 }
1318 if (Verbose && PrintGC) {
1319 size_t new_mem_size = _g1_storage.committed_size();
1320 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1321 old_mem_size/K, aligned_expand_bytes/K,
1322 new_mem_size/K);
1323 }
1324 }
1326 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1327 {
1328 size_t old_mem_size = _g1_storage.committed_size();
1329 size_t aligned_shrink_bytes =
1330 ReservedSpace::page_align_size_down(shrink_bytes);
1331 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1332 HeapRegion::GrainBytes);
1333 size_t num_regions_deleted = 0;
1334 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1336 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1337 if (mr.byte_size() > 0)
1338 _g1_storage.shrink_by(mr.byte_size());
1339 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1341 _g1_committed.set_end(mr.start());
1342 _free_regions -= num_regions_deleted;
1343 _expansion_regions += num_regions_deleted;
1345 // Tell the cardtable about it.
1346 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1348 // And the offset table as well.
1349 _bot_shared->resize(_g1_committed.word_size());
1351 HeapRegionRemSet::shrink_heap(n_regions());
1353 if (Verbose && PrintGC) {
1354 size_t new_mem_size = _g1_storage.committed_size();
1355 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1356 old_mem_size/K, aligned_shrink_bytes/K,
1357 new_mem_size/K);
1358 }
1359 }
1361 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1362 release_gc_alloc_regions(true /* totally */);
1363 tear_down_region_lists(); // We will rebuild them in a moment.
1364 shrink_helper(shrink_bytes);
1365 rebuild_region_lists();
1366 }
1368 // Public methods.
1370 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1371 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1372 #endif // _MSC_VER
1375 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1376 SharedHeap(policy_),
1377 _g1_policy(policy_),
1378 _dirty_card_queue_set(false),
1379 _ref_processor(NULL),
1380 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1381 _bot_shared(NULL),
1382 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1383 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1384 _evac_failure_scan_stack(NULL) ,
1385 _mark_in_progress(false),
1386 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1387 _cur_alloc_region(NULL),
1388 _refine_cte_cl(NULL),
1389 _free_region_list(NULL), _free_region_list_size(0),
1390 _free_regions(0),
1391 _full_collection(false),
1392 _unclean_region_list(),
1393 _unclean_regions_coming(false),
1394 _young_list(new YoungList(this)),
1395 _gc_time_stamp(0),
1396 _surviving_young_words(NULL),
1397 _in_cset_fast_test(NULL),
1398 _in_cset_fast_test_base(NULL),
1399 _dirty_cards_region_list(NULL) {
1400 _g1h = this; // To catch bugs.
1401 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1402 vm_exit_during_initialization("Failed necessary allocation.");
1403 }
1405 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1407 int n_queues = MAX2((int)ParallelGCThreads, 1);
1408 _task_queues = new RefToScanQueueSet(n_queues);
1410 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1411 assert(n_rem_sets > 0, "Invariant.");
1413 HeapRegionRemSetIterator** iter_arr =
1414 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1415 for (int i = 0; i < n_queues; i++) {
1416 iter_arr[i] = new HeapRegionRemSetIterator();
1417 }
1418 _rem_set_iterator = iter_arr;
1420 for (int i = 0; i < n_queues; i++) {
1421 RefToScanQueue* q = new RefToScanQueue();
1422 q->initialize();
1423 _task_queues->register_queue(i, q);
1424 }
1426 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1427 _gc_alloc_regions[ap] = NULL;
1428 _gc_alloc_region_counts[ap] = 0;
1429 _retained_gc_alloc_regions[ap] = NULL;
1430 // by default, we do not retain a GC alloc region for each ap;
1431 // we'll override this, when appropriate, below
1432 _retain_gc_alloc_region[ap] = false;
1433 }
1435 // We will try to remember the last half-full tenured region we
1436 // allocated to at the end of a collection so that we can re-use it
1437 // during the next collection.
1438 _retain_gc_alloc_region[GCAllocForTenured] = true;
1440 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1441 }
1443 jint G1CollectedHeap::initialize() {
1444 CollectedHeap::pre_initialize();
1445 os::enable_vtime();
1447 // Necessary to satisfy locking discipline assertions.
1449 MutexLocker x(Heap_lock);
1451 // While there are no constraints in the GC code that HeapWordSize
1452 // be any particular value, there are multiple other areas in the
1453 // system which believe this to be true (e.g. oop->object_size in some
1454 // cases incorrectly returns the size in wordSize units rather than
1455 // HeapWordSize).
1456 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1458 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1459 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1461 // Ensure that the sizes are properly aligned.
1462 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1463 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1465 _cg1r = new ConcurrentG1Refine();
1467 // Reserve the maximum.
1468 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1469 // Includes the perm-gen.
1471 const size_t total_reserved = max_byte_size + pgs->max_size();
1472 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1474 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1475 HeapRegion::GrainBytes,
1476 false /*ism*/, addr);
1478 if (UseCompressedOops) {
1479 if (addr != NULL && !heap_rs.is_reserved()) {
1480 // Failed to reserve at specified address - the requested memory
1481 // region is taken already, for example, by 'java' launcher.
1482 // Try again to reserver heap higher.
1483 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1484 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1485 false /*ism*/, addr);
1486 if (addr != NULL && !heap_rs0.is_reserved()) {
1487 // Failed to reserve at specified address again - give up.
1488 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1489 assert(addr == NULL, "");
1490 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1491 false /*ism*/, addr);
1492 heap_rs = heap_rs1;
1493 } else {
1494 heap_rs = heap_rs0;
1495 }
1496 }
1497 }
1499 if (!heap_rs.is_reserved()) {
1500 vm_exit_during_initialization("Could not reserve enough space for object heap");
1501 return JNI_ENOMEM;
1502 }
1504 // It is important to do this in a way such that concurrent readers can't
1505 // temporarily think somethings in the heap. (I've actually seen this
1506 // happen in asserts: DLD.)
1507 _reserved.set_word_size(0);
1508 _reserved.set_start((HeapWord*)heap_rs.base());
1509 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1511 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1513 _num_humongous_regions = 0;
1515 // Create the gen rem set (and barrier set) for the entire reserved region.
1516 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1517 set_barrier_set(rem_set()->bs());
1518 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1519 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1520 } else {
1521 vm_exit_during_initialization("G1 requires a mod ref bs.");
1522 return JNI_ENOMEM;
1523 }
1525 // Also create a G1 rem set.
1526 if (G1UseHRIntoRS) {
1527 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1528 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1529 } else {
1530 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1531 return JNI_ENOMEM;
1532 }
1533 } else {
1534 _g1_rem_set = new StupidG1RemSet(this);
1535 }
1537 // Carve out the G1 part of the heap.
1539 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1540 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1541 g1_rs.size()/HeapWordSize);
1542 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1544 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1546 _g1_storage.initialize(g1_rs, 0);
1547 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1548 _g1_max_committed = _g1_committed;
1549 _hrs = new HeapRegionSeq(_expansion_regions);
1550 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1551 guarantee(_cur_alloc_region == NULL, "from constructor");
1553 // 6843694 - ensure that the maximum region index can fit
1554 // in the remembered set structures.
1555 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1556 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1558 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1559 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1560 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1561 "too many cards per region");
1563 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1564 heap_word_size(init_byte_size));
1566 _g1h = this;
1568 // Create the ConcurrentMark data structure and thread.
1569 // (Must do this late, so that "max_regions" is defined.)
1570 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1571 _cmThread = _cm->cmThread();
1573 // ...and the concurrent zero-fill thread, if necessary.
1574 if (G1ConcZeroFill) {
1575 _czft = new ConcurrentZFThread();
1576 }
1578 // Initialize the from_card cache structure of HeapRegionRemSet.
1579 HeapRegionRemSet::init_heap(max_regions());
1581 // Now expand into the initial heap size.
1582 expand(init_byte_size);
1584 // Perform any initialization actions delegated to the policy.
1585 g1_policy()->init();
1587 g1_policy()->note_start_of_mark_thread();
1589 _refine_cte_cl =
1590 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1591 g1_rem_set(),
1592 concurrent_g1_refine());
1593 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1595 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1596 SATB_Q_FL_lock,
1597 G1SATBProcessCompletedThreshold,
1598 Shared_SATB_Q_lock);
1600 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1601 DirtyCardQ_FL_lock,
1602 concurrent_g1_refine()->yellow_zone(),
1603 concurrent_g1_refine()->red_zone(),
1604 Shared_DirtyCardQ_lock);
1606 if (G1DeferredRSUpdate) {
1607 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1608 DirtyCardQ_FL_lock,
1609 -1, // never trigger processing
1610 -1, // no limit on length
1611 Shared_DirtyCardQ_lock,
1612 &JavaThread::dirty_card_queue_set());
1613 }
1614 // In case we're keeping closure specialization stats, initialize those
1615 // counts and that mechanism.
1616 SpecializationStats::clear();
1618 _gc_alloc_region_list = NULL;
1620 // Do later initialization work for concurrent refinement.
1621 _cg1r->init();
1623 return JNI_OK;
1624 }
1626 void G1CollectedHeap::ref_processing_init() {
1627 SharedHeap::ref_processing_init();
1628 MemRegion mr = reserved_region();
1629 _ref_processor = ReferenceProcessor::create_ref_processor(
1630 mr, // span
1631 false, // Reference discovery is not atomic
1632 // (though it shouldn't matter here.)
1633 true, // mt_discovery
1634 NULL, // is alive closure: need to fill this in for efficiency
1635 ParallelGCThreads,
1636 ParallelRefProcEnabled,
1637 true); // Setting next fields of discovered
1638 // lists requires a barrier.
1639 }
1641 size_t G1CollectedHeap::capacity() const {
1642 return _g1_committed.byte_size();
1643 }
1645 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1646 int worker_i) {
1647 // Clean cards in the hot card cache
1648 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set());
1650 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1651 int n_completed_buffers = 0;
1652 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1653 n_completed_buffers++;
1654 }
1655 g1_policy()->record_update_rs_processed_buffers(worker_i,
1656 (double) n_completed_buffers);
1657 dcqs.clear_n_completed_buffers();
1658 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1659 }
1662 // Computes the sum of the storage used by the various regions.
1664 size_t G1CollectedHeap::used() const {
1665 assert(Heap_lock->owner() != NULL,
1666 "Should be owned on this thread's behalf.");
1667 size_t result = _summary_bytes_used;
1668 // Read only once in case it is set to NULL concurrently
1669 HeapRegion* hr = _cur_alloc_region;
1670 if (hr != NULL)
1671 result += hr->used();
1672 return result;
1673 }
1675 size_t G1CollectedHeap::used_unlocked() const {
1676 size_t result = _summary_bytes_used;
1677 return result;
1678 }
1680 class SumUsedClosure: public HeapRegionClosure {
1681 size_t _used;
1682 public:
1683 SumUsedClosure() : _used(0) {}
1684 bool doHeapRegion(HeapRegion* r) {
1685 if (!r->continuesHumongous()) {
1686 _used += r->used();
1687 }
1688 return false;
1689 }
1690 size_t result() { return _used; }
1691 };
1693 size_t G1CollectedHeap::recalculate_used() const {
1694 SumUsedClosure blk;
1695 _hrs->iterate(&blk);
1696 return blk.result();
1697 }
1699 #ifndef PRODUCT
1700 class SumUsedRegionsClosure: public HeapRegionClosure {
1701 size_t _num;
1702 public:
1703 SumUsedRegionsClosure() : _num(0) {}
1704 bool doHeapRegion(HeapRegion* r) {
1705 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1706 _num += 1;
1707 }
1708 return false;
1709 }
1710 size_t result() { return _num; }
1711 };
1713 size_t G1CollectedHeap::recalculate_used_regions() const {
1714 SumUsedRegionsClosure blk;
1715 _hrs->iterate(&blk);
1716 return blk.result();
1717 }
1718 #endif // PRODUCT
1720 size_t G1CollectedHeap::unsafe_max_alloc() {
1721 if (_free_regions > 0) return HeapRegion::GrainBytes;
1722 // otherwise, is there space in the current allocation region?
1724 // We need to store the current allocation region in a local variable
1725 // here. The problem is that this method doesn't take any locks and
1726 // there may be other threads which overwrite the current allocation
1727 // region field. attempt_allocation(), for example, sets it to NULL
1728 // and this can happen *after* the NULL check here but before the call
1729 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1730 // to be a problem in the optimized build, since the two loads of the
1731 // current allocation region field are optimized away.
1732 HeapRegion* car = _cur_alloc_region;
1734 // FIXME: should iterate over all regions?
1735 if (car == NULL) {
1736 return 0;
1737 }
1738 return car->free();
1739 }
1741 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1742 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1743 assert(Heap_lock->is_locked(), "Precondition#2");
1744 GCCauseSetter gcs(this, cause);
1745 switch (cause) {
1746 case GCCause::_heap_inspection:
1747 case GCCause::_heap_dump: {
1748 HandleMark hm;
1749 do_full_collection(false); // don't clear all soft refs
1750 break;
1751 }
1752 default: // XXX FIX ME
1753 ShouldNotReachHere(); // Unexpected use of this function
1754 }
1755 }
1757 void G1CollectedHeap::collect(GCCause::Cause cause) {
1758 // The caller doesn't have the Heap_lock
1759 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1761 int gc_count_before;
1762 {
1763 MutexLocker ml(Heap_lock);
1764 // Read the GC count while holding the Heap_lock
1765 gc_count_before = SharedHeap::heap()->total_collections();
1767 // Don't want to do a GC until cleanup is completed.
1768 wait_for_cleanup_complete();
1769 } // We give up heap lock; VMThread::execute gets it back below
1770 switch (cause) {
1771 case GCCause::_scavenge_alot: {
1772 // Do an incremental pause, which might sometimes be abandoned.
1773 VM_G1IncCollectionPause op(gc_count_before, cause);
1774 VMThread::execute(&op);
1775 break;
1776 }
1777 default: {
1778 // In all other cases, we currently do a full gc.
1779 VM_G1CollectFull op(gc_count_before, cause);
1780 VMThread::execute(&op);
1781 }
1782 }
1783 }
1785 bool G1CollectedHeap::is_in(const void* p) const {
1786 if (_g1_committed.contains(p)) {
1787 HeapRegion* hr = _hrs->addr_to_region(p);
1788 return hr->is_in(p);
1789 } else {
1790 return _perm_gen->as_gen()->is_in(p);
1791 }
1792 }
1794 // Iteration functions.
1796 // Iterates an OopClosure over all ref-containing fields of objects
1797 // within a HeapRegion.
1799 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1800 MemRegion _mr;
1801 OopClosure* _cl;
1802 public:
1803 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1804 : _mr(mr), _cl(cl) {}
1805 bool doHeapRegion(HeapRegion* r) {
1806 if (! r->continuesHumongous()) {
1807 r->oop_iterate(_cl);
1808 }
1809 return false;
1810 }
1811 };
1813 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1814 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1815 _hrs->iterate(&blk);
1816 if (do_perm) {
1817 perm_gen()->oop_iterate(cl);
1818 }
1819 }
1821 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1822 IterateOopClosureRegionClosure blk(mr, cl);
1823 _hrs->iterate(&blk);
1824 if (do_perm) {
1825 perm_gen()->oop_iterate(cl);
1826 }
1827 }
1829 // Iterates an ObjectClosure over all objects within a HeapRegion.
1831 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1832 ObjectClosure* _cl;
1833 public:
1834 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1835 bool doHeapRegion(HeapRegion* r) {
1836 if (! r->continuesHumongous()) {
1837 r->object_iterate(_cl);
1838 }
1839 return false;
1840 }
1841 };
1843 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1844 IterateObjectClosureRegionClosure blk(cl);
1845 _hrs->iterate(&blk);
1846 if (do_perm) {
1847 perm_gen()->object_iterate(cl);
1848 }
1849 }
1851 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1852 // FIXME: is this right?
1853 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1854 }
1856 // Calls a SpaceClosure on a HeapRegion.
1858 class SpaceClosureRegionClosure: public HeapRegionClosure {
1859 SpaceClosure* _cl;
1860 public:
1861 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1862 bool doHeapRegion(HeapRegion* r) {
1863 _cl->do_space(r);
1864 return false;
1865 }
1866 };
1868 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1869 SpaceClosureRegionClosure blk(cl);
1870 _hrs->iterate(&blk);
1871 }
1873 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1874 _hrs->iterate(cl);
1875 }
1877 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1878 HeapRegionClosure* cl) {
1879 _hrs->iterate_from(r, cl);
1880 }
1882 void
1883 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1884 _hrs->iterate_from(idx, cl);
1885 }
1887 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1889 void
1890 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1891 int worker,
1892 jint claim_value) {
1893 const size_t regions = n_regions();
1894 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1895 // try to spread out the starting points of the workers
1896 const size_t start_index = regions / worker_num * (size_t) worker;
1898 // each worker will actually look at all regions
1899 for (size_t count = 0; count < regions; ++count) {
1900 const size_t index = (start_index + count) % regions;
1901 assert(0 <= index && index < regions, "sanity");
1902 HeapRegion* r = region_at(index);
1903 // we'll ignore "continues humongous" regions (we'll process them
1904 // when we come across their corresponding "start humongous"
1905 // region) and regions already claimed
1906 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1907 continue;
1908 }
1909 // OK, try to claim it
1910 if (r->claimHeapRegion(claim_value)) {
1911 // success!
1912 assert(!r->continuesHumongous(), "sanity");
1913 if (r->startsHumongous()) {
1914 // If the region is "starts humongous" we'll iterate over its
1915 // "continues humongous" first; in fact we'll do them
1916 // first. The order is important. In on case, calling the
1917 // closure on the "starts humongous" region might de-allocate
1918 // and clear all its "continues humongous" regions and, as a
1919 // result, we might end up processing them twice. So, we'll do
1920 // them first (notice: most closures will ignore them anyway) and
1921 // then we'll do the "starts humongous" region.
1922 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1923 HeapRegion* chr = region_at(ch_index);
1925 // if the region has already been claimed or it's not
1926 // "continues humongous" we're done
1927 if (chr->claim_value() == claim_value ||
1928 !chr->continuesHumongous()) {
1929 break;
1930 }
1932 // Noone should have claimed it directly. We can given
1933 // that we claimed its "starts humongous" region.
1934 assert(chr->claim_value() != claim_value, "sanity");
1935 assert(chr->humongous_start_region() == r, "sanity");
1937 if (chr->claimHeapRegion(claim_value)) {
1938 // we should always be able to claim it; noone else should
1939 // be trying to claim this region
1941 bool res2 = cl->doHeapRegion(chr);
1942 assert(!res2, "Should not abort");
1944 // Right now, this holds (i.e., no closure that actually
1945 // does something with "continues humongous" regions
1946 // clears them). We might have to weaken it in the future,
1947 // but let's leave these two asserts here for extra safety.
1948 assert(chr->continuesHumongous(), "should still be the case");
1949 assert(chr->humongous_start_region() == r, "sanity");
1950 } else {
1951 guarantee(false, "we should not reach here");
1952 }
1953 }
1954 }
1956 assert(!r->continuesHumongous(), "sanity");
1957 bool res = cl->doHeapRegion(r);
1958 assert(!res, "Should not abort");
1959 }
1960 }
1961 }
1963 class ResetClaimValuesClosure: public HeapRegionClosure {
1964 public:
1965 bool doHeapRegion(HeapRegion* r) {
1966 r->set_claim_value(HeapRegion::InitialClaimValue);
1967 return false;
1968 }
1969 };
1971 void
1972 G1CollectedHeap::reset_heap_region_claim_values() {
1973 ResetClaimValuesClosure blk;
1974 heap_region_iterate(&blk);
1975 }
1977 #ifdef ASSERT
1978 // This checks whether all regions in the heap have the correct claim
1979 // value. I also piggy-backed on this a check to ensure that the
1980 // humongous_start_region() information on "continues humongous"
1981 // regions is correct.
1983 class CheckClaimValuesClosure : public HeapRegionClosure {
1984 private:
1985 jint _claim_value;
1986 size_t _failures;
1987 HeapRegion* _sh_region;
1988 public:
1989 CheckClaimValuesClosure(jint claim_value) :
1990 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1991 bool doHeapRegion(HeapRegion* r) {
1992 if (r->claim_value() != _claim_value) {
1993 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1994 "claim value = %d, should be %d",
1995 r->bottom(), r->end(), r->claim_value(),
1996 _claim_value);
1997 ++_failures;
1998 }
1999 if (!r->isHumongous()) {
2000 _sh_region = NULL;
2001 } else if (r->startsHumongous()) {
2002 _sh_region = r;
2003 } else if (r->continuesHumongous()) {
2004 if (r->humongous_start_region() != _sh_region) {
2005 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2006 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2007 r->bottom(), r->end(),
2008 r->humongous_start_region(),
2009 _sh_region);
2010 ++_failures;
2011 }
2012 }
2013 return false;
2014 }
2015 size_t failures() {
2016 return _failures;
2017 }
2018 };
2020 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2021 CheckClaimValuesClosure cl(claim_value);
2022 heap_region_iterate(&cl);
2023 return cl.failures() == 0;
2024 }
2025 #endif // ASSERT
2027 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2028 HeapRegion* r = g1_policy()->collection_set();
2029 while (r != NULL) {
2030 HeapRegion* next = r->next_in_collection_set();
2031 if (cl->doHeapRegion(r)) {
2032 cl->incomplete();
2033 return;
2034 }
2035 r = next;
2036 }
2037 }
2039 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2040 HeapRegionClosure *cl) {
2041 assert(r->in_collection_set(),
2042 "Start region must be a member of the collection set.");
2043 HeapRegion* cur = r;
2044 while (cur != NULL) {
2045 HeapRegion* next = cur->next_in_collection_set();
2046 if (cl->doHeapRegion(cur) && false) {
2047 cl->incomplete();
2048 return;
2049 }
2050 cur = next;
2051 }
2052 cur = g1_policy()->collection_set();
2053 while (cur != r) {
2054 HeapRegion* next = cur->next_in_collection_set();
2055 if (cl->doHeapRegion(cur) && false) {
2056 cl->incomplete();
2057 return;
2058 }
2059 cur = next;
2060 }
2061 }
2063 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2064 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2065 }
2068 Space* G1CollectedHeap::space_containing(const void* addr) const {
2069 Space* res = heap_region_containing(addr);
2070 if (res == NULL)
2071 res = perm_gen()->space_containing(addr);
2072 return res;
2073 }
2075 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2076 Space* sp = space_containing(addr);
2077 if (sp != NULL) {
2078 return sp->block_start(addr);
2079 }
2080 return NULL;
2081 }
2083 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2084 Space* sp = space_containing(addr);
2085 assert(sp != NULL, "block_size of address outside of heap");
2086 return sp->block_size(addr);
2087 }
2089 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2090 Space* sp = space_containing(addr);
2091 return sp->block_is_obj(addr);
2092 }
2094 bool G1CollectedHeap::supports_tlab_allocation() const {
2095 return true;
2096 }
2098 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2099 return HeapRegion::GrainBytes;
2100 }
2102 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2103 // Return the remaining space in the cur alloc region, but not less than
2104 // the min TLAB size.
2105 // Also, no more than half the region size, since we can't allow tlabs to
2106 // grow big enough to accomodate humongous objects.
2108 // We need to story it locally, since it might change between when we
2109 // test for NULL and when we use it later.
2110 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2111 if (cur_alloc_space == NULL) {
2112 return HeapRegion::GrainBytes/2;
2113 } else {
2114 return MAX2(MIN2(cur_alloc_space->free(),
2115 (size_t)(HeapRegion::GrainBytes/2)),
2116 (size_t)MinTLABSize);
2117 }
2118 }
2120 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2121 bool dummy;
2122 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2123 }
2125 bool G1CollectedHeap::allocs_are_zero_filled() {
2126 return false;
2127 }
2129 size_t G1CollectedHeap::large_typearray_limit() {
2130 // FIXME
2131 return HeapRegion::GrainBytes/HeapWordSize;
2132 }
2134 size_t G1CollectedHeap::max_capacity() const {
2135 return g1_reserved_obj_bytes();
2136 }
2138 jlong G1CollectedHeap::millis_since_last_gc() {
2139 // assert(false, "NYI");
2140 return 0;
2141 }
2144 void G1CollectedHeap::prepare_for_verify() {
2145 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2146 ensure_parsability(false);
2147 }
2148 g1_rem_set()->prepare_for_verify();
2149 }
2151 class VerifyLivenessOopClosure: public OopClosure {
2152 G1CollectedHeap* g1h;
2153 public:
2154 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2155 g1h = _g1h;
2156 }
2157 void do_oop(narrowOop *p) { do_oop_work(p); }
2158 void do_oop( oop *p) { do_oop_work(p); }
2160 template <class T> void do_oop_work(T *p) {
2161 oop obj = oopDesc::load_decode_heap_oop(p);
2162 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2163 "Dead object referenced by a not dead object");
2164 }
2165 };
2167 class VerifyObjsInRegionClosure: public ObjectClosure {
2168 private:
2169 G1CollectedHeap* _g1h;
2170 size_t _live_bytes;
2171 HeapRegion *_hr;
2172 bool _use_prev_marking;
2173 public:
2174 // use_prev_marking == true -> use "prev" marking information,
2175 // use_prev_marking == false -> use "next" marking information
2176 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2177 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2178 _g1h = G1CollectedHeap::heap();
2179 }
2180 void do_object(oop o) {
2181 VerifyLivenessOopClosure isLive(_g1h);
2182 assert(o != NULL, "Huh?");
2183 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2184 o->oop_iterate(&isLive);
2185 if (!_hr->obj_allocated_since_prev_marking(o))
2186 _live_bytes += (o->size() * HeapWordSize);
2187 }
2188 }
2189 size_t live_bytes() { return _live_bytes; }
2190 };
2192 class PrintObjsInRegionClosure : public ObjectClosure {
2193 HeapRegion *_hr;
2194 G1CollectedHeap *_g1;
2195 public:
2196 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2197 _g1 = G1CollectedHeap::heap();
2198 };
2200 void do_object(oop o) {
2201 if (o != NULL) {
2202 HeapWord *start = (HeapWord *) o;
2203 size_t word_sz = o->size();
2204 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2205 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2206 (void*) o, word_sz,
2207 _g1->isMarkedPrev(o),
2208 _g1->isMarkedNext(o),
2209 _hr->obj_allocated_since_prev_marking(o));
2210 HeapWord *end = start + word_sz;
2211 HeapWord *cur;
2212 int *val;
2213 for (cur = start; cur < end; cur++) {
2214 val = (int *) cur;
2215 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2216 }
2217 }
2218 }
2219 };
2221 class VerifyRegionClosure: public HeapRegionClosure {
2222 private:
2223 bool _allow_dirty;
2224 bool _par;
2225 bool _use_prev_marking;
2226 bool _failures;
2227 public:
2228 // use_prev_marking == true -> use "prev" marking information,
2229 // use_prev_marking == false -> use "next" marking information
2230 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2231 : _allow_dirty(allow_dirty),
2232 _par(par),
2233 _use_prev_marking(use_prev_marking),
2234 _failures(false) {}
2236 bool failures() {
2237 return _failures;
2238 }
2240 bool doHeapRegion(HeapRegion* r) {
2241 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2242 "Should be unclaimed at verify points.");
2243 if (!r->continuesHumongous()) {
2244 bool failures = false;
2245 r->verify(_allow_dirty, _use_prev_marking, &failures);
2246 if (failures) {
2247 _failures = true;
2248 } else {
2249 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2250 r->object_iterate(¬_dead_yet_cl);
2251 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2252 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2253 "max_live_bytes "SIZE_FORMAT" "
2254 "< calculated "SIZE_FORMAT,
2255 r->bottom(), r->end(),
2256 r->max_live_bytes(),
2257 not_dead_yet_cl.live_bytes());
2258 _failures = true;
2259 }
2260 }
2261 }
2262 return false; // stop the region iteration if we hit a failure
2263 }
2264 };
2266 class VerifyRootsClosure: public OopsInGenClosure {
2267 private:
2268 G1CollectedHeap* _g1h;
2269 bool _use_prev_marking;
2270 bool _failures;
2271 public:
2272 // use_prev_marking == true -> use "prev" marking information,
2273 // use_prev_marking == false -> use "next" marking information
2274 VerifyRootsClosure(bool use_prev_marking) :
2275 _g1h(G1CollectedHeap::heap()),
2276 _use_prev_marking(use_prev_marking),
2277 _failures(false) { }
2279 bool failures() { return _failures; }
2281 template <class T> void do_oop_nv(T* p) {
2282 T heap_oop = oopDesc::load_heap_oop(p);
2283 if (!oopDesc::is_null(heap_oop)) {
2284 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2285 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2286 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2287 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2288 obj->print_on(gclog_or_tty);
2289 _failures = true;
2290 }
2291 }
2292 }
2294 void do_oop(oop* p) { do_oop_nv(p); }
2295 void do_oop(narrowOop* p) { do_oop_nv(p); }
2296 };
2298 // This is the task used for parallel heap verification.
2300 class G1ParVerifyTask: public AbstractGangTask {
2301 private:
2302 G1CollectedHeap* _g1h;
2303 bool _allow_dirty;
2304 bool _use_prev_marking;
2305 bool _failures;
2307 public:
2308 // use_prev_marking == true -> use "prev" marking information,
2309 // use_prev_marking == false -> use "next" marking information
2310 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2311 bool use_prev_marking) :
2312 AbstractGangTask("Parallel verify task"),
2313 _g1h(g1h),
2314 _allow_dirty(allow_dirty),
2315 _use_prev_marking(use_prev_marking),
2316 _failures(false) { }
2318 bool failures() {
2319 return _failures;
2320 }
2322 void work(int worker_i) {
2323 HandleMark hm;
2324 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2325 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2326 HeapRegion::ParVerifyClaimValue);
2327 if (blk.failures()) {
2328 _failures = true;
2329 }
2330 }
2331 };
2333 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2334 verify(allow_dirty, silent, /* use_prev_marking */ true);
2335 }
2337 void G1CollectedHeap::verify(bool allow_dirty,
2338 bool silent,
2339 bool use_prev_marking) {
2340 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2341 if (!silent) { gclog_or_tty->print("roots "); }
2342 VerifyRootsClosure rootsCl(use_prev_marking);
2343 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2344 process_strong_roots(true, // activate StrongRootsScope
2345 false,
2346 SharedHeap::SO_AllClasses,
2347 &rootsCl,
2348 &blobsCl,
2349 &rootsCl);
2350 bool failures = rootsCl.failures();
2351 rem_set()->invalidate(perm_gen()->used_region(), false);
2352 if (!silent) { gclog_or_tty->print("heapRegions "); }
2353 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2354 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2355 "sanity check");
2357 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2358 int n_workers = workers()->total_workers();
2359 set_par_threads(n_workers);
2360 workers()->run_task(&task);
2361 set_par_threads(0);
2362 if (task.failures()) {
2363 failures = true;
2364 }
2366 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2367 "sanity check");
2369 reset_heap_region_claim_values();
2371 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2372 "sanity check");
2373 } else {
2374 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2375 _hrs->iterate(&blk);
2376 if (blk.failures()) {
2377 failures = true;
2378 }
2379 }
2380 if (!silent) gclog_or_tty->print("remset ");
2381 rem_set()->verify();
2383 if (failures) {
2384 gclog_or_tty->print_cr("Heap:");
2385 print_on(gclog_or_tty, true /* extended */);
2386 gclog_or_tty->print_cr("");
2387 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2388 concurrent_mark()->print_reachable(use_prev_marking,
2389 "failed-verification");
2390 }
2391 gclog_or_tty->flush();
2392 }
2393 guarantee(!failures, "there should not have been any failures");
2394 } else {
2395 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2396 }
2397 }
2399 class PrintRegionClosure: public HeapRegionClosure {
2400 outputStream* _st;
2401 public:
2402 PrintRegionClosure(outputStream* st) : _st(st) {}
2403 bool doHeapRegion(HeapRegion* r) {
2404 r->print_on(_st);
2405 return false;
2406 }
2407 };
2409 void G1CollectedHeap::print() const { print_on(tty); }
2411 void G1CollectedHeap::print_on(outputStream* st) const {
2412 print_on(st, PrintHeapAtGCExtended);
2413 }
2415 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2416 st->print(" %-20s", "garbage-first heap");
2417 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2418 capacity()/K, used_unlocked()/K);
2419 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2420 _g1_storage.low_boundary(),
2421 _g1_storage.high(),
2422 _g1_storage.high_boundary());
2423 st->cr();
2424 st->print(" region size " SIZE_FORMAT "K, ",
2425 HeapRegion::GrainBytes/K);
2426 size_t young_regions = _young_list->length();
2427 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2428 young_regions, young_regions * HeapRegion::GrainBytes / K);
2429 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2430 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2431 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2432 st->cr();
2433 perm()->as_gen()->print_on(st);
2434 if (extended) {
2435 st->cr();
2436 print_on_extended(st);
2437 }
2438 }
2440 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2441 PrintRegionClosure blk(st);
2442 _hrs->iterate(&blk);
2443 }
2445 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2446 if (ParallelGCThreads > 0) {
2447 workers()->print_worker_threads_on(st);
2448 }
2450 _cmThread->print_on(st);
2451 st->cr();
2453 _cm->print_worker_threads_on(st);
2455 _cg1r->print_worker_threads_on(st);
2457 _czft->print_on(st);
2458 st->cr();
2459 }
2461 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2462 if (ParallelGCThreads > 0) {
2463 workers()->threads_do(tc);
2464 }
2465 tc->do_thread(_cmThread);
2466 _cg1r->threads_do(tc);
2467 tc->do_thread(_czft);
2468 }
2470 void G1CollectedHeap::print_tracing_info() const {
2471 // We'll overload this to mean "trace GC pause statistics."
2472 if (TraceGen0Time || TraceGen1Time) {
2473 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2474 // to that.
2475 g1_policy()->print_tracing_info();
2476 }
2477 if (G1SummarizeRSetStats) {
2478 g1_rem_set()->print_summary_info();
2479 }
2480 if (G1SummarizeConcurrentMark) {
2481 concurrent_mark()->print_summary_info();
2482 }
2483 if (G1SummarizeZFStats) {
2484 ConcurrentZFThread::print_summary_info();
2485 }
2486 g1_policy()->print_yg_surv_rate_info();
2488 SpecializationStats::print();
2489 }
2492 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2493 HeapRegion* hr = heap_region_containing(addr);
2494 if (hr == NULL) {
2495 return 0;
2496 } else {
2497 return 1;
2498 }
2499 }
2501 G1CollectedHeap* G1CollectedHeap::heap() {
2502 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2503 "not a garbage-first heap");
2504 return _g1h;
2505 }
2507 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2508 // always_do_update_barrier = false;
2509 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2510 // Call allocation profiler
2511 AllocationProfiler::iterate_since_last_gc();
2512 // Fill TLAB's and such
2513 ensure_parsability(true);
2514 }
2516 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2517 // FIXME: what is this about?
2518 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2519 // is set.
2520 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2521 "derived pointer present"));
2522 // always_do_update_barrier = true;
2523 }
2525 void G1CollectedHeap::do_collection_pause() {
2526 // Read the GC count while holding the Heap_lock
2527 // we need to do this _before_ wait_for_cleanup_complete(), to
2528 // ensure that we do not give up the heap lock and potentially
2529 // pick up the wrong count
2530 int gc_count_before = SharedHeap::heap()->total_collections();
2532 // Don't want to do a GC pause while cleanup is being completed!
2533 wait_for_cleanup_complete();
2535 g1_policy()->record_stop_world_start();
2536 {
2537 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2538 VM_G1IncCollectionPause op(gc_count_before);
2539 VMThread::execute(&op);
2540 }
2541 }
2543 void
2544 G1CollectedHeap::doConcurrentMark() {
2545 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2546 if (!_cmThread->in_progress()) {
2547 _cmThread->set_started();
2548 CGC_lock->notify();
2549 }
2550 }
2552 class VerifyMarkedObjsClosure: public ObjectClosure {
2553 G1CollectedHeap* _g1h;
2554 public:
2555 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2556 void do_object(oop obj) {
2557 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2558 "markandsweep mark should agree with concurrent deadness");
2559 }
2560 };
2562 void
2563 G1CollectedHeap::checkConcurrentMark() {
2564 VerifyMarkedObjsClosure verifycl(this);
2565 // MutexLockerEx x(getMarkBitMapLock(),
2566 // Mutex::_no_safepoint_check_flag);
2567 object_iterate(&verifycl, false);
2568 }
2570 void G1CollectedHeap::do_sync_mark() {
2571 _cm->checkpointRootsInitial();
2572 _cm->markFromRoots();
2573 _cm->checkpointRootsFinal(false);
2574 }
2576 // <NEW PREDICTION>
2578 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2579 bool young) {
2580 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2581 }
2583 void G1CollectedHeap::check_if_region_is_too_expensive(double
2584 predicted_time_ms) {
2585 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2586 }
2588 size_t G1CollectedHeap::pending_card_num() {
2589 size_t extra_cards = 0;
2590 JavaThread *curr = Threads::first();
2591 while (curr != NULL) {
2592 DirtyCardQueue& dcq = curr->dirty_card_queue();
2593 extra_cards += dcq.size();
2594 curr = curr->next();
2595 }
2596 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2597 size_t buffer_size = dcqs.buffer_size();
2598 size_t buffer_num = dcqs.completed_buffers_num();
2599 return buffer_size * buffer_num + extra_cards;
2600 }
2602 size_t G1CollectedHeap::max_pending_card_num() {
2603 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2604 size_t buffer_size = dcqs.buffer_size();
2605 size_t buffer_num = dcqs.completed_buffers_num();
2606 int thread_num = Threads::number_of_threads();
2607 return (buffer_num + thread_num) * buffer_size;
2608 }
2610 size_t G1CollectedHeap::cards_scanned() {
2611 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2612 return g1_rset->cardsScanned();
2613 }
2615 void
2616 G1CollectedHeap::setup_surviving_young_words() {
2617 guarantee( _surviving_young_words == NULL, "pre-condition" );
2618 size_t array_length = g1_policy()->young_cset_length();
2619 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2620 if (_surviving_young_words == NULL) {
2621 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2622 "Not enough space for young surv words summary.");
2623 }
2624 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2625 #ifdef ASSERT
2626 for (size_t i = 0; i < array_length; ++i) {
2627 assert( _surviving_young_words[i] == 0, "memset above" );
2628 }
2629 #endif // !ASSERT
2630 }
2632 void
2633 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2634 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2635 size_t array_length = g1_policy()->young_cset_length();
2636 for (size_t i = 0; i < array_length; ++i)
2637 _surviving_young_words[i] += surv_young_words[i];
2638 }
2640 void
2641 G1CollectedHeap::cleanup_surviving_young_words() {
2642 guarantee( _surviving_young_words != NULL, "pre-condition" );
2643 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2644 _surviving_young_words = NULL;
2645 }
2647 // </NEW PREDICTION>
2649 struct PrepareForRSScanningClosure : public HeapRegionClosure {
2650 bool doHeapRegion(HeapRegion *r) {
2651 r->rem_set()->set_iter_claimed(0);
2652 return false;
2653 }
2654 };
2656 void
2657 G1CollectedHeap::do_collection_pause_at_safepoint() {
2658 if (PrintHeapAtGC) {
2659 Universe::print_heap_before_gc();
2660 }
2662 {
2663 ResourceMark rm;
2665 char verbose_str[128];
2666 sprintf(verbose_str, "GC pause ");
2667 if (g1_policy()->in_young_gc_mode()) {
2668 if (g1_policy()->full_young_gcs())
2669 strcat(verbose_str, "(young)");
2670 else
2671 strcat(verbose_str, "(partial)");
2672 }
2673 if (g1_policy()->should_initiate_conc_mark())
2674 strcat(verbose_str, " (initial-mark)");
2676 // if PrintGCDetails is on, we'll print long statistics information
2677 // in the collector policy code, so let's not print this as the output
2678 // is messy if we do.
2679 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2680 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2681 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2683 TraceMemoryManagerStats tms(false /* fullGC */);
2685 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2686 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2687 guarantee(!is_gc_active(), "collection is not reentrant");
2688 assert(regions_accounted_for(), "Region leakage!");
2690 increment_gc_time_stamp();
2692 if (g1_policy()->in_young_gc_mode()) {
2693 assert(check_young_list_well_formed(),
2694 "young list should be well formed");
2695 }
2697 if (GC_locker::is_active()) {
2698 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2699 }
2701 bool abandoned = false;
2702 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2703 IsGCActiveMark x;
2705 gc_prologue(false);
2706 increment_total_collections(false /* full gc */);
2708 #if G1_REM_SET_LOGGING
2709 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2710 print();
2711 #endif
2713 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2714 HandleMark hm; // Discard invalid handles created during verification
2715 prepare_for_verify();
2716 gclog_or_tty->print(" VerifyBeforeGC:");
2717 Universe::verify(false);
2718 }
2720 COMPILER2_PRESENT(DerivedPointerTable::clear());
2722 // We want to turn off ref discovery, if necessary, and turn it back on
2723 // on again later if we do. XXX Dubious: why is discovery disabled?
2724 bool was_enabled = ref_processor()->discovery_enabled();
2725 if (was_enabled) ref_processor()->disable_discovery();
2727 // Forget the current alloc region (we might even choose it to be part
2728 // of the collection set!).
2729 abandon_cur_alloc_region();
2731 // The elapsed time induced by the start time below deliberately elides
2732 // the possible verification above.
2733 double start_time_sec = os::elapsedTime();
2734 size_t start_used_bytes = used();
2736 g1_policy()->record_collection_pause_start(start_time_sec,
2737 start_used_bytes);
2739 guarantee(_in_cset_fast_test == NULL, "invariant");
2740 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2741 _in_cset_fast_test_length = max_regions();
2742 _in_cset_fast_test_base =
2743 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2744 memset(_in_cset_fast_test_base, false,
2745 _in_cset_fast_test_length * sizeof(bool));
2746 // We're biasing _in_cset_fast_test to avoid subtracting the
2747 // beginning of the heap every time we want to index; basically
2748 // it's the same with what we do with the card table.
2749 _in_cset_fast_test = _in_cset_fast_test_base -
2750 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2752 #if SCAN_ONLY_VERBOSE
2753 _young_list->print();
2754 #endif // SCAN_ONLY_VERBOSE
2756 if (g1_policy()->should_initiate_conc_mark()) {
2757 concurrent_mark()->checkpointRootsInitialPre();
2758 }
2759 save_marks();
2761 // We must do this before any possible evacuation that should propagate
2762 // marks.
2763 if (mark_in_progress()) {
2764 double start_time_sec = os::elapsedTime();
2766 _cm->drainAllSATBBuffers();
2767 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2768 g1_policy()->record_satb_drain_time(finish_mark_ms);
2769 }
2770 // Record the number of elements currently on the mark stack, so we
2771 // only iterate over these. (Since evacuation may add to the mark
2772 // stack, doing more exposes race conditions.) If no mark is in
2773 // progress, this will be zero.
2774 _cm->set_oops_do_bound();
2776 assert(regions_accounted_for(), "Region leakage.");
2778 if (mark_in_progress())
2779 concurrent_mark()->newCSet();
2781 // Now choose the CS.
2782 g1_policy()->choose_collection_set();
2784 // We may abandon a pause if we find no region that will fit in the MMU
2785 // pause.
2786 bool abandoned = (g1_policy()->collection_set() == NULL);
2788 // Nothing to do if we were unable to choose a collection set.
2789 if (!abandoned) {
2790 #if G1_REM_SET_LOGGING
2791 gclog_or_tty->print_cr("\nAfter pause, heap:");
2792 print();
2793 #endif
2794 PrepareForRSScanningClosure prepare_for_rs_scan;
2795 collection_set_iterate(&prepare_for_rs_scan);
2797 setup_surviving_young_words();
2799 // Set up the gc allocation regions.
2800 get_gc_alloc_regions();
2802 // Actually do the work...
2803 evacuate_collection_set();
2804 free_collection_set(g1_policy()->collection_set());
2805 g1_policy()->clear_collection_set();
2807 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2808 // this is more for peace of mind; we're nulling them here and
2809 // we're expecting them to be null at the beginning of the next GC
2810 _in_cset_fast_test = NULL;
2811 _in_cset_fast_test_base = NULL;
2813 cleanup_surviving_young_words();
2815 if (g1_policy()->in_young_gc_mode()) {
2816 _young_list->reset_sampled_info();
2817 assert(check_young_list_empty(true),
2818 "young list should be empty");
2820 #if SCAN_ONLY_VERBOSE
2821 _young_list->print();
2822 #endif // SCAN_ONLY_VERBOSE
2824 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2825 _young_list->first_survivor_region(),
2826 _young_list->last_survivor_region());
2827 _young_list->reset_auxilary_lists();
2828 }
2829 } else {
2830 if (_in_cset_fast_test != NULL) {
2831 assert(_in_cset_fast_test_base != NULL, "Since _in_cset_fast_test isn't");
2832 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2833 // this is more for peace of mind; we're nulling them here and
2834 // we're expecting them to be null at the beginning of the next GC
2835 _in_cset_fast_test = NULL;
2836 _in_cset_fast_test_base = NULL;
2837 }
2838 // This looks confusing, because the DPT should really be empty
2839 // at this point -- since we have not done any collection work,
2840 // there should not be any derived pointers in the table to update;
2841 // however, there is some additional state in the DPT which is
2842 // reset at the end of the (null) "gc" here via the following call.
2843 // A better approach might be to split off that state resetting work
2844 // into a separate method that asserts that the DPT is empty and call
2845 // that here. That is deferred for now.
2846 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2847 }
2849 if (evacuation_failed()) {
2850 _summary_bytes_used = recalculate_used();
2851 } else {
2852 // The "used" of the the collection set have already been subtracted
2853 // when they were freed. Add in the bytes evacuated.
2854 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2855 }
2857 if (g1_policy()->in_young_gc_mode() &&
2858 g1_policy()->should_initiate_conc_mark()) {
2859 concurrent_mark()->checkpointRootsInitialPost();
2860 set_marking_started();
2861 // CAUTION: after the doConcurrentMark() call below,
2862 // the concurrent marking thread(s) could be running
2863 // concurrently with us. Make sure that anything after
2864 // this point does not assume that we are the only GC thread
2865 // running. Note: of course, the actual marking work will
2866 // not start until the safepoint itself is released in
2867 // ConcurrentGCThread::safepoint_desynchronize().
2868 doConcurrentMark();
2869 }
2871 #if SCAN_ONLY_VERBOSE
2872 _young_list->print();
2873 #endif // SCAN_ONLY_VERBOSE
2875 double end_time_sec = os::elapsedTime();
2876 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2877 g1_policy()->record_pause_time_ms(pause_time_ms);
2878 g1_policy()->record_collection_pause_end(abandoned);
2880 assert(regions_accounted_for(), "Region leakage.");
2882 MemoryService::track_memory_usage();
2884 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2885 HandleMark hm; // Discard invalid handles created during verification
2886 gclog_or_tty->print(" VerifyAfterGC:");
2887 prepare_for_verify();
2888 Universe::verify(false);
2889 }
2891 if (was_enabled) ref_processor()->enable_discovery();
2893 {
2894 size_t expand_bytes = g1_policy()->expansion_amount();
2895 if (expand_bytes > 0) {
2896 size_t bytes_before = capacity();
2897 expand(expand_bytes);
2898 }
2899 }
2901 if (mark_in_progress()) {
2902 concurrent_mark()->update_g1_committed();
2903 }
2905 #ifdef TRACESPINNING
2906 ParallelTaskTerminator::print_termination_counts();
2907 #endif
2909 gc_epilogue(false);
2910 }
2912 assert(verify_region_lists(), "Bad region lists.");
2914 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2915 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2916 print_tracing_info();
2917 vm_exit(-1);
2918 }
2919 }
2921 if (PrintHeapAtGC) {
2922 Universe::print_heap_after_gc();
2923 }
2924 if (G1SummarizeRSetStats &&
2925 (G1SummarizeRSetStatsPeriod > 0) &&
2926 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
2927 g1_rem_set()->print_summary_info();
2928 }
2929 }
2931 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2932 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2933 // make sure we don't call set_gc_alloc_region() multiple times on
2934 // the same region
2935 assert(r == NULL || !r->is_gc_alloc_region(),
2936 "shouldn't already be a GC alloc region");
2937 HeapWord* original_top = NULL;
2938 if (r != NULL)
2939 original_top = r->top();
2941 // We will want to record the used space in r as being there before gc.
2942 // One we install it as a GC alloc region it's eligible for allocation.
2943 // So record it now and use it later.
2944 size_t r_used = 0;
2945 if (r != NULL) {
2946 r_used = r->used();
2948 if (ParallelGCThreads > 0) {
2949 // need to take the lock to guard against two threads calling
2950 // get_gc_alloc_region concurrently (very unlikely but...)
2951 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2952 r->save_marks();
2953 }
2954 }
2955 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2956 _gc_alloc_regions[purpose] = r;
2957 if (old_alloc_region != NULL) {
2958 // Replace aliases too.
2959 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2960 if (_gc_alloc_regions[ap] == old_alloc_region) {
2961 _gc_alloc_regions[ap] = r;
2962 }
2963 }
2964 }
2965 if (r != NULL) {
2966 push_gc_alloc_region(r);
2967 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2968 // We are using a region as a GC alloc region after it has been used
2969 // as a mutator allocation region during the current marking cycle.
2970 // The mutator-allocated objects are currently implicitly marked, but
2971 // when we move hr->next_top_at_mark_start() forward at the the end
2972 // of the GC pause, they won't be. We therefore mark all objects in
2973 // the "gap". We do this object-by-object, since marking densely
2974 // does not currently work right with marking bitmap iteration. This
2975 // means we rely on TLAB filling at the start of pauses, and no
2976 // "resuscitation" of filled TLAB's. If we want to do this, we need
2977 // to fix the marking bitmap iteration.
2978 HeapWord* curhw = r->next_top_at_mark_start();
2979 HeapWord* t = original_top;
2981 while (curhw < t) {
2982 oop cur = (oop)curhw;
2983 // We'll assume parallel for generality. This is rare code.
2984 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2985 curhw = curhw + cur->size();
2986 }
2987 assert(curhw == t, "Should have parsed correctly.");
2988 }
2989 if (G1PolicyVerbose > 1) {
2990 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2991 "for survivors:", r->bottom(), original_top, r->end());
2992 r->print();
2993 }
2994 g1_policy()->record_before_bytes(r_used);
2995 }
2996 }
2998 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2999 assert(Thread::current()->is_VM_thread() ||
3000 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
3001 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3002 "Precondition.");
3003 hr->set_is_gc_alloc_region(true);
3004 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3005 _gc_alloc_region_list = hr;
3006 }
3008 #ifdef G1_DEBUG
3009 class FindGCAllocRegion: public HeapRegionClosure {
3010 public:
3011 bool doHeapRegion(HeapRegion* r) {
3012 if (r->is_gc_alloc_region()) {
3013 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3014 r->hrs_index(), r->bottom());
3015 }
3016 return false;
3017 }
3018 };
3019 #endif // G1_DEBUG
3021 void G1CollectedHeap::forget_alloc_region_list() {
3022 assert(Thread::current()->is_VM_thread(), "Precondition");
3023 while (_gc_alloc_region_list != NULL) {
3024 HeapRegion* r = _gc_alloc_region_list;
3025 assert(r->is_gc_alloc_region(), "Invariant.");
3026 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3027 // newly allocated data in order to be able to apply deferred updates
3028 // before the GC is done for verification purposes (i.e to allow
3029 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3030 // collection.
3031 r->ContiguousSpace::set_saved_mark();
3032 _gc_alloc_region_list = r->next_gc_alloc_region();
3033 r->set_next_gc_alloc_region(NULL);
3034 r->set_is_gc_alloc_region(false);
3035 if (r->is_survivor()) {
3036 if (r->is_empty()) {
3037 r->set_not_young();
3038 } else {
3039 _young_list->add_survivor_region(r);
3040 }
3041 }
3042 if (r->is_empty()) {
3043 ++_free_regions;
3044 }
3045 }
3046 #ifdef G1_DEBUG
3047 FindGCAllocRegion fa;
3048 heap_region_iterate(&fa);
3049 #endif // G1_DEBUG
3050 }
3053 bool G1CollectedHeap::check_gc_alloc_regions() {
3054 // TODO: allocation regions check
3055 return true;
3056 }
3058 void G1CollectedHeap::get_gc_alloc_regions() {
3059 // First, let's check that the GC alloc region list is empty (it should)
3060 assert(_gc_alloc_region_list == NULL, "invariant");
3062 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3063 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3064 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3066 // Create new GC alloc regions.
3067 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3068 _retained_gc_alloc_regions[ap] = NULL;
3070 if (alloc_region != NULL) {
3071 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3073 // let's make sure that the GC alloc region is not tagged as such
3074 // outside a GC operation
3075 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3077 if (alloc_region->in_collection_set() ||
3078 alloc_region->top() == alloc_region->end() ||
3079 alloc_region->top() == alloc_region->bottom()) {
3080 // we will discard the current GC alloc region if it's in the
3081 // collection set (it can happen!), if it's already full (no
3082 // point in using it), or if it's empty (this means that it
3083 // was emptied during a cleanup and it should be on the free
3084 // list now).
3086 alloc_region = NULL;
3087 }
3088 }
3090 if (alloc_region == NULL) {
3091 // we will get a new GC alloc region
3092 alloc_region = newAllocRegionWithExpansion(ap, 0);
3093 } else {
3094 // the region was retained from the last collection
3095 ++_gc_alloc_region_counts[ap];
3096 }
3098 if (alloc_region != NULL) {
3099 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3100 set_gc_alloc_region(ap, alloc_region);
3101 }
3103 assert(_gc_alloc_regions[ap] == NULL ||
3104 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3105 "the GC alloc region should be tagged as such");
3106 assert(_gc_alloc_regions[ap] == NULL ||
3107 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3108 "the GC alloc region should be the same as the GC alloc list head");
3109 }
3110 // Set alternative regions for allocation purposes that have reached
3111 // their limit.
3112 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3113 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3114 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3115 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3116 }
3117 }
3118 assert(check_gc_alloc_regions(), "alloc regions messed up");
3119 }
3121 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3122 // We keep a separate list of all regions that have been alloc regions in
3123 // the current collection pause. Forget that now. This method will
3124 // untag the GC alloc regions and tear down the GC alloc region
3125 // list. It's desirable that no regions are tagged as GC alloc
3126 // outside GCs.
3127 forget_alloc_region_list();
3129 // The current alloc regions contain objs that have survived
3130 // collection. Make them no longer GC alloc regions.
3131 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3132 HeapRegion* r = _gc_alloc_regions[ap];
3133 _retained_gc_alloc_regions[ap] = NULL;
3134 _gc_alloc_region_counts[ap] = 0;
3136 if (r != NULL) {
3137 // we retain nothing on _gc_alloc_regions between GCs
3138 set_gc_alloc_region(ap, NULL);
3140 if (r->is_empty()) {
3141 // we didn't actually allocate anything in it; let's just put
3142 // it on the free list
3143 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3144 r->set_zero_fill_complete();
3145 put_free_region_on_list_locked(r);
3146 } else if (_retain_gc_alloc_region[ap] && !totally) {
3147 // retain it so that we can use it at the beginning of the next GC
3148 _retained_gc_alloc_regions[ap] = r;
3149 }
3150 }
3151 }
3152 }
3154 #ifndef PRODUCT
3155 // Useful for debugging
3157 void G1CollectedHeap::print_gc_alloc_regions() {
3158 gclog_or_tty->print_cr("GC alloc regions");
3159 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3160 HeapRegion* r = _gc_alloc_regions[ap];
3161 if (r == NULL) {
3162 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3163 } else {
3164 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3165 ap, r->bottom(), r->used());
3166 }
3167 }
3168 }
3169 #endif // PRODUCT
3171 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3172 _drain_in_progress = false;
3173 set_evac_failure_closure(cl);
3174 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3175 }
3177 void G1CollectedHeap::finalize_for_evac_failure() {
3178 assert(_evac_failure_scan_stack != NULL &&
3179 _evac_failure_scan_stack->length() == 0,
3180 "Postcondition");
3181 assert(!_drain_in_progress, "Postcondition");
3182 delete _evac_failure_scan_stack;
3183 _evac_failure_scan_stack = NULL;
3184 }
3188 // *** Sequential G1 Evacuation
3190 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3191 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3192 // let the caller handle alloc failure
3193 if (alloc_region == NULL) return NULL;
3194 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3195 "Either the object is humongous or the region isn't");
3196 HeapWord* block = alloc_region->allocate(word_size);
3197 if (block == NULL) {
3198 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3199 }
3200 return block;
3201 }
3203 class G1IsAliveClosure: public BoolObjectClosure {
3204 G1CollectedHeap* _g1;
3205 public:
3206 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3207 void do_object(oop p) { assert(false, "Do not call."); }
3208 bool do_object_b(oop p) {
3209 // It is reachable if it is outside the collection set, or is inside
3210 // and forwarded.
3212 #ifdef G1_DEBUG
3213 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3214 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3215 !_g1->obj_in_cs(p) || p->is_forwarded());
3216 #endif // G1_DEBUG
3218 return !_g1->obj_in_cs(p) || p->is_forwarded();
3219 }
3220 };
3222 class G1KeepAliveClosure: public OopClosure {
3223 G1CollectedHeap* _g1;
3224 public:
3225 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3226 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3227 void do_oop( oop* p) {
3228 oop obj = *p;
3229 #ifdef G1_DEBUG
3230 if (PrintGC && Verbose) {
3231 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3232 p, (void*) obj, (void*) *p);
3233 }
3234 #endif // G1_DEBUG
3236 if (_g1->obj_in_cs(obj)) {
3237 assert( obj->is_forwarded(), "invariant" );
3238 *p = obj->forwardee();
3239 #ifdef G1_DEBUG
3240 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3241 (void*) obj, (void*) *p);
3242 #endif // G1_DEBUG
3243 }
3244 }
3245 };
3247 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3248 private:
3249 G1CollectedHeap* _g1;
3250 G1RemSet* _g1_rem_set;
3251 public:
3252 UpdateRSetImmediate(G1CollectedHeap* g1) :
3253 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3255 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3256 virtual void do_oop( oop* p) { do_oop_work(p); }
3257 template <class T> void do_oop_work(T* p) {
3258 assert(_from->is_in_reserved(p), "paranoia");
3259 T heap_oop = oopDesc::load_heap_oop(p);
3260 if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
3261 _g1_rem_set->par_write_ref(_from, p, 0);
3262 }
3263 }
3264 };
3266 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3267 private:
3268 G1CollectedHeap* _g1;
3269 DirtyCardQueue *_dcq;
3270 CardTableModRefBS* _ct_bs;
3272 public:
3273 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3274 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3276 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3277 virtual void do_oop( oop* p) { do_oop_work(p); }
3278 template <class T> void do_oop_work(T* p) {
3279 assert(_from->is_in_reserved(p), "paranoia");
3280 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3281 !_from->is_survivor()) {
3282 size_t card_index = _ct_bs->index_for(p);
3283 if (_ct_bs->mark_card_deferred(card_index)) {
3284 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3285 }
3286 }
3287 }
3288 };
3292 class RemoveSelfPointerClosure: public ObjectClosure {
3293 private:
3294 G1CollectedHeap* _g1;
3295 ConcurrentMark* _cm;
3296 HeapRegion* _hr;
3297 size_t _prev_marked_bytes;
3298 size_t _next_marked_bytes;
3299 OopsInHeapRegionClosure *_cl;
3300 public:
3301 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3302 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3303 _next_marked_bytes(0), _cl(cl) {}
3305 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3306 size_t next_marked_bytes() { return _next_marked_bytes; }
3308 // The original idea here was to coalesce evacuated and dead objects.
3309 // However that caused complications with the block offset table (BOT).
3310 // In particular if there were two TLABs, one of them partially refined.
3311 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3312 // The BOT entries of the unrefined part of TLAB_2 point to the start
3313 // of TLAB_2. If the last object of the TLAB_1 and the first object
3314 // of TLAB_2 are coalesced, then the cards of the unrefined part
3315 // would point into middle of the filler object.
3316 //
3317 // The current approach is to not coalesce and leave the BOT contents intact.
3318 void do_object(oop obj) {
3319 if (obj->is_forwarded() && obj->forwardee() == obj) {
3320 // The object failed to move.
3321 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3322 _cm->markPrev(obj);
3323 assert(_cm->isPrevMarked(obj), "Should be marked!");
3324 _prev_marked_bytes += (obj->size() * HeapWordSize);
3325 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3326 _cm->markAndGrayObjectIfNecessary(obj);
3327 }
3328 obj->set_mark(markOopDesc::prototype());
3329 // While we were processing RSet buffers during the
3330 // collection, we actually didn't scan any cards on the
3331 // collection set, since we didn't want to update remebered
3332 // sets with entries that point into the collection set, given
3333 // that live objects fromthe collection set are about to move
3334 // and such entries will be stale very soon. This change also
3335 // dealt with a reliability issue which involved scanning a
3336 // card in the collection set and coming across an array that
3337 // was being chunked and looking malformed. The problem is
3338 // that, if evacuation fails, we might have remembered set
3339 // entries missing given that we skipped cards on the
3340 // collection set. So, we'll recreate such entries now.
3341 obj->oop_iterate(_cl);
3342 assert(_cm->isPrevMarked(obj), "Should be marked!");
3343 } else {
3344 // The object has been either evacuated or is dead. Fill it with a
3345 // dummy object.
3346 MemRegion mr((HeapWord*)obj, obj->size());
3347 CollectedHeap::fill_with_object(mr);
3348 _cm->clearRangeBothMaps(mr);
3349 }
3350 }
3351 };
3353 void G1CollectedHeap::remove_self_forwarding_pointers() {
3354 UpdateRSetImmediate immediate_update(_g1h);
3355 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3356 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3357 OopsInHeapRegionClosure *cl;
3358 if (G1DeferredRSUpdate) {
3359 cl = &deferred_update;
3360 } else {
3361 cl = &immediate_update;
3362 }
3363 HeapRegion* cur = g1_policy()->collection_set();
3364 while (cur != NULL) {
3365 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3367 RemoveSelfPointerClosure rspc(_g1h, cl);
3368 if (cur->evacuation_failed()) {
3369 assert(cur->in_collection_set(), "bad CS");
3370 cl->set_region(cur);
3371 cur->object_iterate(&rspc);
3373 // A number of manipulations to make the TAMS be the current top,
3374 // and the marked bytes be the ones observed in the iteration.
3375 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3376 // The comments below are the postconditions achieved by the
3377 // calls. Note especially the last such condition, which says that
3378 // the count of marked bytes has been properly restored.
3379 cur->note_start_of_marking(false);
3380 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3381 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3382 // _next_marked_bytes == prev_marked_bytes.
3383 cur->note_end_of_marking();
3384 // _prev_top_at_mark_start == top(),
3385 // _prev_marked_bytes == prev_marked_bytes
3386 }
3387 // If there is no mark in progress, we modified the _next variables
3388 // above needlessly, but harmlessly.
3389 if (_g1h->mark_in_progress()) {
3390 cur->note_start_of_marking(false);
3391 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3392 // _next_marked_bytes == next_marked_bytes.
3393 }
3395 // Now make sure the region has the right index in the sorted array.
3396 g1_policy()->note_change_in_marked_bytes(cur);
3397 }
3398 cur = cur->next_in_collection_set();
3399 }
3400 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3402 // Now restore saved marks, if any.
3403 if (_objs_with_preserved_marks != NULL) {
3404 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3405 assert(_objs_with_preserved_marks->length() ==
3406 _preserved_marks_of_objs->length(), "Both or none.");
3407 guarantee(_objs_with_preserved_marks->length() ==
3408 _preserved_marks_of_objs->length(), "Both or none.");
3409 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3410 oop obj = _objs_with_preserved_marks->at(i);
3411 markOop m = _preserved_marks_of_objs->at(i);
3412 obj->set_mark(m);
3413 }
3414 // Delete the preserved marks growable arrays (allocated on the C heap).
3415 delete _objs_with_preserved_marks;
3416 delete _preserved_marks_of_objs;
3417 _objs_with_preserved_marks = NULL;
3418 _preserved_marks_of_objs = NULL;
3419 }
3420 }
3422 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3423 _evac_failure_scan_stack->push(obj);
3424 }
3426 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3427 assert(_evac_failure_scan_stack != NULL, "precondition");
3429 while (_evac_failure_scan_stack->length() > 0) {
3430 oop obj = _evac_failure_scan_stack->pop();
3431 _evac_failure_closure->set_region(heap_region_containing(obj));
3432 obj->oop_iterate_backwards(_evac_failure_closure);
3433 }
3434 }
3436 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3437 markOop m = old->mark();
3438 // forward to self
3439 assert(!old->is_forwarded(), "precondition");
3441 old->forward_to(old);
3442 handle_evacuation_failure_common(old, m);
3443 }
3445 oop
3446 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3447 oop old) {
3448 markOop m = old->mark();
3449 oop forward_ptr = old->forward_to_atomic(old);
3450 if (forward_ptr == NULL) {
3451 // Forward-to-self succeeded.
3452 if (_evac_failure_closure != cl) {
3453 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3454 assert(!_drain_in_progress,
3455 "Should only be true while someone holds the lock.");
3456 // Set the global evac-failure closure to the current thread's.
3457 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3458 set_evac_failure_closure(cl);
3459 // Now do the common part.
3460 handle_evacuation_failure_common(old, m);
3461 // Reset to NULL.
3462 set_evac_failure_closure(NULL);
3463 } else {
3464 // The lock is already held, and this is recursive.
3465 assert(_drain_in_progress, "This should only be the recursive case.");
3466 handle_evacuation_failure_common(old, m);
3467 }
3468 return old;
3469 } else {
3470 // Someone else had a place to copy it.
3471 return forward_ptr;
3472 }
3473 }
3475 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3476 set_evacuation_failed(true);
3478 preserve_mark_if_necessary(old, m);
3480 HeapRegion* r = heap_region_containing(old);
3481 if (!r->evacuation_failed()) {
3482 r->set_evacuation_failed(true);
3483 if (G1PrintRegions) {
3484 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3485 "["PTR_FORMAT","PTR_FORMAT")\n",
3486 r, r->bottom(), r->end());
3487 }
3488 }
3490 push_on_evac_failure_scan_stack(old);
3492 if (!_drain_in_progress) {
3493 // prevent recursion in copy_to_survivor_space()
3494 _drain_in_progress = true;
3495 drain_evac_failure_scan_stack();
3496 _drain_in_progress = false;
3497 }
3498 }
3500 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3501 if (m != markOopDesc::prototype()) {
3502 if (_objs_with_preserved_marks == NULL) {
3503 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3504 _objs_with_preserved_marks =
3505 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3506 _preserved_marks_of_objs =
3507 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3508 }
3509 _objs_with_preserved_marks->push(obj);
3510 _preserved_marks_of_objs->push(m);
3511 }
3512 }
3514 // *** Parallel G1 Evacuation
3516 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3517 size_t word_size) {
3518 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3519 // let the caller handle alloc failure
3520 if (alloc_region == NULL) return NULL;
3522 HeapWord* block = alloc_region->par_allocate(word_size);
3523 if (block == NULL) {
3524 MutexLockerEx x(par_alloc_during_gc_lock(),
3525 Mutex::_no_safepoint_check_flag);
3526 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3527 }
3528 return block;
3529 }
3531 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3532 bool par) {
3533 // Another thread might have obtained alloc_region for the given
3534 // purpose, and might be attempting to allocate in it, and might
3535 // succeed. Therefore, we can't do the "finalization" stuff on the
3536 // region below until we're sure the last allocation has happened.
3537 // We ensure this by allocating the remaining space with a garbage
3538 // object.
3539 if (par) par_allocate_remaining_space(alloc_region);
3540 // Now we can do the post-GC stuff on the region.
3541 alloc_region->note_end_of_copying();
3542 g1_policy()->record_after_bytes(alloc_region->used());
3543 }
3545 HeapWord*
3546 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3547 HeapRegion* alloc_region,
3548 bool par,
3549 size_t word_size) {
3550 HeapWord* block = NULL;
3551 // In the parallel case, a previous thread to obtain the lock may have
3552 // already assigned a new gc_alloc_region.
3553 if (alloc_region != _gc_alloc_regions[purpose]) {
3554 assert(par, "But should only happen in parallel case.");
3555 alloc_region = _gc_alloc_regions[purpose];
3556 if (alloc_region == NULL) return NULL;
3557 block = alloc_region->par_allocate(word_size);
3558 if (block != NULL) return block;
3559 // Otherwise, continue; this new region is empty, too.
3560 }
3561 assert(alloc_region != NULL, "We better have an allocation region");
3562 retire_alloc_region(alloc_region, par);
3564 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3565 // Cannot allocate more regions for the given purpose.
3566 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3567 // Is there an alternative?
3568 if (purpose != alt_purpose) {
3569 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3570 // Has not the alternative region been aliased?
3571 if (alloc_region != alt_region && alt_region != NULL) {
3572 // Try to allocate in the alternative region.
3573 if (par) {
3574 block = alt_region->par_allocate(word_size);
3575 } else {
3576 block = alt_region->allocate(word_size);
3577 }
3578 // Make an alias.
3579 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3580 if (block != NULL) {
3581 return block;
3582 }
3583 retire_alloc_region(alt_region, par);
3584 }
3585 // Both the allocation region and the alternative one are full
3586 // and aliased, replace them with a new allocation region.
3587 purpose = alt_purpose;
3588 } else {
3589 set_gc_alloc_region(purpose, NULL);
3590 return NULL;
3591 }
3592 }
3594 // Now allocate a new region for allocation.
3595 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3597 // let the caller handle alloc failure
3598 if (alloc_region != NULL) {
3600 assert(check_gc_alloc_regions(), "alloc regions messed up");
3601 assert(alloc_region->saved_mark_at_top(),
3602 "Mark should have been saved already.");
3603 // We used to assert that the region was zero-filled here, but no
3604 // longer.
3606 // This must be done last: once it's installed, other regions may
3607 // allocate in it (without holding the lock.)
3608 set_gc_alloc_region(purpose, alloc_region);
3610 if (par) {
3611 block = alloc_region->par_allocate(word_size);
3612 } else {
3613 block = alloc_region->allocate(word_size);
3614 }
3615 // Caller handles alloc failure.
3616 } else {
3617 // This sets other apis using the same old alloc region to NULL, also.
3618 set_gc_alloc_region(purpose, NULL);
3619 }
3620 return block; // May be NULL.
3621 }
3623 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3624 HeapWord* block = NULL;
3625 size_t free_words;
3626 do {
3627 free_words = r->free()/HeapWordSize;
3628 // If there's too little space, no one can allocate, so we're done.
3629 if (free_words < (size_t)oopDesc::header_size()) return;
3630 // Otherwise, try to claim it.
3631 block = r->par_allocate(free_words);
3632 } while (block == NULL);
3633 fill_with_object(block, free_words);
3634 }
3636 #ifndef PRODUCT
3637 bool GCLabBitMapClosure::do_bit(size_t offset) {
3638 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3639 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3640 return true;
3641 }
3642 #endif // PRODUCT
3644 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3645 : _g1h(g1h),
3646 _refs(g1h->task_queue(queue_num)),
3647 _dcq(&g1h->dirty_card_queue_set()),
3648 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3649 _g1_rem(g1h->g1_rem_set()),
3650 _hash_seed(17), _queue_num(queue_num),
3651 _term_attempts(0),
3652 _age_table(false),
3653 #if G1_DETAILED_STATS
3654 _pushes(0), _pops(0), _steals(0),
3655 _steal_attempts(0), _overflow_pushes(0),
3656 #endif
3657 _strong_roots_time(0), _term_time(0),
3658 _alloc_buffer_waste(0), _undo_waste(0)
3659 {
3660 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3661 // we "sacrifice" entry 0 to keep track of surviving bytes for
3662 // non-young regions (where the age is -1)
3663 // We also add a few elements at the beginning and at the end in
3664 // an attempt to eliminate cache contention
3665 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3666 size_t array_length = PADDING_ELEM_NUM +
3667 real_length +
3668 PADDING_ELEM_NUM;
3669 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3670 if (_surviving_young_words_base == NULL)
3671 vm_exit_out_of_memory(array_length * sizeof(size_t),
3672 "Not enough space for young surv histo.");
3673 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3674 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3676 _overflowed_refs = new OverflowQueue(10);
3678 _start = os::elapsedTime();
3679 }
3681 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3682 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3683 _par_scan_state(par_scan_state) { }
3685 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3686 // This is called _after_ do_oop_work has been called, hence after
3687 // the object has been relocated to its new location and *p points
3688 // to its new location.
3690 T heap_oop = oopDesc::load_heap_oop(p);
3691 if (!oopDesc::is_null(heap_oop)) {
3692 oop obj = oopDesc::decode_heap_oop(heap_oop);
3693 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3694 "shouldn't still be in the CSet if evacuation didn't fail.");
3695 HeapWord* addr = (HeapWord*)obj;
3696 if (_g1->is_in_g1_reserved(addr))
3697 _cm->grayRoot(oop(addr));
3698 }
3699 }
3701 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3702 size_t word_sz = old->size();
3703 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3704 // +1 to make the -1 indexes valid...
3705 int young_index = from_region->young_index_in_cset()+1;
3706 assert( (from_region->is_young() && young_index > 0) ||
3707 (!from_region->is_young() && young_index == 0), "invariant" );
3708 G1CollectorPolicy* g1p = _g1->g1_policy();
3709 markOop m = old->mark();
3710 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3711 : m->age();
3712 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3713 word_sz);
3714 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3715 oop obj = oop(obj_ptr);
3717 if (obj_ptr == NULL) {
3718 // This will either forward-to-self, or detect that someone else has
3719 // installed a forwarding pointer.
3720 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3721 return _g1->handle_evacuation_failure_par(cl, old);
3722 }
3724 // We're going to allocate linearly, so might as well prefetch ahead.
3725 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3727 oop forward_ptr = old->forward_to_atomic(obj);
3728 if (forward_ptr == NULL) {
3729 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3730 if (g1p->track_object_age(alloc_purpose)) {
3731 // We could simply do obj->incr_age(). However, this causes a
3732 // performance issue. obj->incr_age() will first check whether
3733 // the object has a displaced mark by checking its mark word;
3734 // getting the mark word from the new location of the object
3735 // stalls. So, given that we already have the mark word and we
3736 // are about to install it anyway, it's better to increase the
3737 // age on the mark word, when the object does not have a
3738 // displaced mark word. We're not expecting many objects to have
3739 // a displaced marked word, so that case is not optimized
3740 // further (it could be...) and we simply call obj->incr_age().
3742 if (m->has_displaced_mark_helper()) {
3743 // in this case, we have to install the mark word first,
3744 // otherwise obj looks to be forwarded (the old mark word,
3745 // which contains the forward pointer, was copied)
3746 obj->set_mark(m);
3747 obj->incr_age();
3748 } else {
3749 m = m->incr_age();
3750 obj->set_mark(m);
3751 }
3752 _par_scan_state->age_table()->add(obj, word_sz);
3753 } else {
3754 obj->set_mark(m);
3755 }
3757 // preserve "next" mark bit
3758 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3759 if (!use_local_bitmaps ||
3760 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3761 // if we couldn't mark it on the local bitmap (this happens when
3762 // the object was not allocated in the GCLab), we have to bite
3763 // the bullet and do the standard parallel mark
3764 _cm->markAndGrayObjectIfNecessary(obj);
3765 }
3766 #if 1
3767 if (_g1->isMarkedNext(old)) {
3768 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3769 }
3770 #endif
3771 }
3773 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3774 surv_young_words[young_index] += word_sz;
3776 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3777 arrayOop(old)->set_length(0);
3778 oop* old_p = set_partial_array_mask(old);
3779 _par_scan_state->push_on_queue(old_p);
3780 } else {
3781 // No point in using the slower heap_region_containing() method,
3782 // given that we know obj is in the heap.
3783 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3784 obj->oop_iterate_backwards(_scanner);
3785 }
3786 } else {
3787 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3788 obj = forward_ptr;
3789 }
3790 return obj;
3791 }
3793 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
3794 template <class T>
3795 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
3796 ::do_oop_work(T* p) {
3797 oop obj = oopDesc::load_decode_heap_oop(p);
3798 assert(barrier != G1BarrierRS || obj != NULL,
3799 "Precondition: G1BarrierRS implies obj is nonNull");
3801 // here the null check is implicit in the cset_fast_test() test
3802 if (_g1->in_cset_fast_test(obj)) {
3803 #if G1_REM_SET_LOGGING
3804 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
3805 "into CS.", p, (void*) obj);
3806 #endif
3807 if (obj->is_forwarded()) {
3808 oopDesc::encode_store_heap_oop(p, obj->forwardee());
3809 } else {
3810 oop copy_oop = copy_to_survivor_space(obj);
3811 oopDesc::encode_store_heap_oop(p, copy_oop);
3812 }
3813 // When scanning the RS, we only care about objs in CS.
3814 if (barrier == G1BarrierRS) {
3815 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3816 }
3817 }
3819 if (barrier == G1BarrierEvac && obj != NULL) {
3820 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3821 }
3823 if (do_gen_barrier && obj != NULL) {
3824 par_do_barrier(p);
3825 }
3826 }
3828 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
3829 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
3831 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
3832 assert(has_partial_array_mask(p), "invariant");
3833 oop old = clear_partial_array_mask(p);
3834 assert(old->is_objArray(), "must be obj array");
3835 assert(old->is_forwarded(), "must be forwarded");
3836 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
3838 objArrayOop obj = objArrayOop(old->forwardee());
3839 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
3840 // Process ParGCArrayScanChunk elements now
3841 // and push the remainder back onto queue
3842 int start = arrayOop(old)->length();
3843 int end = obj->length();
3844 int remainder = end - start;
3845 assert(start <= end, "just checking");
3846 if (remainder > 2 * ParGCArrayScanChunk) {
3847 // Test above combines last partial chunk with a full chunk
3848 end = start + ParGCArrayScanChunk;
3849 arrayOop(old)->set_length(end);
3850 // Push remainder.
3851 oop* old_p = set_partial_array_mask(old);
3852 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
3853 _par_scan_state->push_on_queue(old_p);
3854 } else {
3855 // Restore length so that the heap remains parsable in
3856 // case of evacuation failure.
3857 arrayOop(old)->set_length(end);
3858 }
3859 _scanner.set_region(_g1->heap_region_containing_raw(obj));
3860 // process our set of indices (include header in first chunk)
3861 obj->oop_iterate_range(&_scanner, start, end);
3862 }
3864 class G1ParEvacuateFollowersClosure : public VoidClosure {
3865 protected:
3866 G1CollectedHeap* _g1h;
3867 G1ParScanThreadState* _par_scan_state;
3868 RefToScanQueueSet* _queues;
3869 ParallelTaskTerminator* _terminator;
3871 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3872 RefToScanQueueSet* queues() { return _queues; }
3873 ParallelTaskTerminator* terminator() { return _terminator; }
3875 public:
3876 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
3877 G1ParScanThreadState* par_scan_state,
3878 RefToScanQueueSet* queues,
3879 ParallelTaskTerminator* terminator)
3880 : _g1h(g1h), _par_scan_state(par_scan_state),
3881 _queues(queues), _terminator(terminator) {}
3883 void do_void() {
3884 G1ParScanThreadState* pss = par_scan_state();
3885 while (true) {
3886 pss->trim_queue();
3887 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
3889 StarTask stolen_task;
3890 if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
3891 IF_G1_DETAILED_STATS(pss->note_steal());
3893 // slightly paranoid tests; I'm trying to catch potential
3894 // problems before we go into push_on_queue to know where the
3895 // problem is coming from
3896 assert((oop*)stolen_task != NULL, "Error");
3897 if (stolen_task.is_narrow()) {
3898 assert(UseCompressedOops, "Error");
3899 narrowOop* p = (narrowOop*) stolen_task;
3900 assert(has_partial_array_mask(p) ||
3901 _g1h->is_in_g1_reserved(oopDesc::load_decode_heap_oop(p)), "Error");
3902 pss->push_on_queue(p);
3903 } else {
3904 oop* p = (oop*) stolen_task;
3905 assert(has_partial_array_mask(p) || _g1h->is_in_g1_reserved(*p), "Error");
3906 pss->push_on_queue(p);
3907 }
3908 continue;
3909 }
3910 pss->start_term_time();
3911 if (terminator()->offer_termination()) break;
3912 pss->end_term_time();
3913 }
3914 pss->end_term_time();
3915 pss->retire_alloc_buffers();
3916 }
3917 };
3919 class G1ParTask : public AbstractGangTask {
3920 protected:
3921 G1CollectedHeap* _g1h;
3922 RefToScanQueueSet *_queues;
3923 ParallelTaskTerminator _terminator;
3924 int _n_workers;
3926 Mutex _stats_lock;
3927 Mutex* stats_lock() { return &_stats_lock; }
3929 size_t getNCards() {
3930 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
3931 / G1BlockOffsetSharedArray::N_bytes;
3932 }
3934 public:
3935 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
3936 : AbstractGangTask("G1 collection"),
3937 _g1h(g1h),
3938 _queues(task_queues),
3939 _terminator(workers, _queues),
3940 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
3941 _n_workers(workers)
3942 {}
3944 RefToScanQueueSet* queues() { return _queues; }
3946 RefToScanQueue *work_queue(int i) {
3947 return queues()->queue(i);
3948 }
3950 void work(int i) {
3951 if (i >= _n_workers) return; // no work needed this round
3952 ResourceMark rm;
3953 HandleMark hm;
3955 G1ParScanThreadState pss(_g1h, i);
3956 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
3957 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
3958 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
3960 pss.set_evac_closure(&scan_evac_cl);
3961 pss.set_evac_failure_closure(&evac_failure_cl);
3962 pss.set_partial_scan_closure(&partial_scan_cl);
3964 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
3965 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
3966 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
3967 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
3969 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
3970 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
3971 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
3973 OopsInHeapRegionClosure *scan_root_cl;
3974 OopsInHeapRegionClosure *scan_perm_cl;
3975 OopsInHeapRegionClosure *scan_so_cl;
3977 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
3978 scan_root_cl = &scan_mark_root_cl;
3979 scan_perm_cl = &scan_mark_perm_cl;
3980 scan_so_cl = &scan_mark_heap_rs_cl;
3981 } else {
3982 scan_root_cl = &only_scan_root_cl;
3983 scan_perm_cl = &only_scan_perm_cl;
3984 scan_so_cl = &only_scan_heap_rs_cl;
3985 }
3987 pss.start_strong_roots();
3988 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
3989 SharedHeap::SO_AllClasses,
3990 scan_root_cl,
3991 &push_heap_rs_cl,
3992 scan_so_cl,
3993 scan_perm_cl,
3994 i);
3995 pss.end_strong_roots();
3996 {
3997 double start = os::elapsedTime();
3998 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
3999 evac.do_void();
4000 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4001 double term_ms = pss.term_time()*1000.0;
4002 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4003 _g1h->g1_policy()->record_termination_time(i, term_ms);
4004 }
4005 if (G1UseSurvivorSpaces) {
4006 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4007 }
4008 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4010 // Clean up any par-expanded rem sets.
4011 HeapRegionRemSet::par_cleanup();
4013 MutexLocker x(stats_lock());
4014 if (ParallelGCVerbose) {
4015 gclog_or_tty->print("Thread %d complete:\n", i);
4016 #if G1_DETAILED_STATS
4017 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4018 pss.pushes(),
4019 pss.pops(),
4020 pss.overflow_pushes(),
4021 pss.steals(),
4022 pss.steal_attempts());
4023 #endif
4024 double elapsed = pss.elapsed();
4025 double strong_roots = pss.strong_roots_time();
4026 double term = pss.term_time();
4027 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4028 " Strong roots: %7.2f ms (%6.2f%%)\n"
4029 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4030 elapsed * 1000.0,
4031 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4032 term * 1000.0, (term*100.0/elapsed),
4033 pss.term_attempts());
4034 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4035 gclog_or_tty->print(" Waste: %8dK\n"
4036 " Alloc Buffer: %8dK\n"
4037 " Undo: %8dK\n",
4038 (total_waste * HeapWordSize) / K,
4039 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4040 (pss.undo_waste() * HeapWordSize) / K);
4041 }
4043 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4044 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4045 }
4046 };
4048 // *** Common G1 Evacuation Stuff
4050 void
4051 G1CollectedHeap::
4052 g1_process_strong_roots(bool collecting_perm_gen,
4053 SharedHeap::ScanningOption so,
4054 OopClosure* scan_non_heap_roots,
4055 OopsInHeapRegionClosure* scan_rs,
4056 OopsInHeapRegionClosure* scan_so,
4057 OopsInGenClosure* scan_perm,
4058 int worker_i) {
4059 // First scan the strong roots, including the perm gen.
4060 double ext_roots_start = os::elapsedTime();
4061 double closure_app_time_sec = 0.0;
4063 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4064 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4065 buf_scan_perm.set_generation(perm_gen());
4067 // Walk the code cache w/o buffering, because StarTask cannot handle
4068 // unaligned oop locations.
4069 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4071 process_strong_roots(false, // no scoping; this is parallel code
4072 collecting_perm_gen, so,
4073 &buf_scan_non_heap_roots,
4074 &eager_scan_code_roots,
4075 &buf_scan_perm);
4076 // Finish up any enqueued closure apps.
4077 buf_scan_non_heap_roots.done();
4078 buf_scan_perm.done();
4079 double ext_roots_end = os::elapsedTime();
4080 g1_policy()->reset_obj_copy_time(worker_i);
4081 double obj_copy_time_sec =
4082 buf_scan_non_heap_roots.closure_app_seconds() +
4083 buf_scan_perm.closure_app_seconds();
4084 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4085 double ext_root_time_ms =
4086 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4087 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4089 // Scan strong roots in mark stack.
4090 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4091 concurrent_mark()->oops_do(scan_non_heap_roots);
4092 }
4093 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4094 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4096 // XXX What should this be doing in the parallel case?
4097 g1_policy()->record_collection_pause_end_CH_strong_roots();
4098 if (scan_so != NULL) {
4099 scan_scan_only_set(scan_so, worker_i);
4100 }
4101 // Now scan the complement of the collection set.
4102 if (scan_rs != NULL) {
4103 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4104 }
4105 // Finish with the ref_processor roots.
4106 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4107 ref_processor()->oops_do(scan_non_heap_roots);
4108 }
4109 g1_policy()->record_collection_pause_end_G1_strong_roots();
4110 _process_strong_tasks->all_tasks_completed();
4111 }
4113 void
4114 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4115 OopsInHeapRegionClosure* oc,
4116 int worker_i) {
4117 HeapWord* startAddr = r->bottom();
4118 HeapWord* endAddr = r->used_region().end();
4120 oc->set_region(r);
4122 HeapWord* p = r->bottom();
4123 HeapWord* t = r->top();
4124 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4125 while (p < t) {
4126 oop obj = oop(p);
4127 p += obj->oop_iterate(oc);
4128 }
4129 }
4131 void
4132 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4133 int worker_i) {
4134 double start = os::elapsedTime();
4136 BufferingOopsInHeapRegionClosure boc(oc);
4138 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4139 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4141 OopsInHeapRegionClosure *foc;
4142 if (g1_policy()->should_initiate_conc_mark())
4143 foc = &scan_and_mark;
4144 else
4145 foc = &scan_only;
4147 HeapRegion* hr;
4148 int n = 0;
4149 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4150 scan_scan_only_region(hr, foc, worker_i);
4151 ++n;
4152 }
4153 boc.done();
4155 double closure_app_s = boc.closure_app_seconds();
4156 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4157 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4158 g1_policy()->record_scan_only_time(worker_i, ms, n);
4159 }
4161 void
4162 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4163 OopClosure* non_root_closure) {
4164 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4165 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4166 }
4169 class SaveMarksClosure: public HeapRegionClosure {
4170 public:
4171 bool doHeapRegion(HeapRegion* r) {
4172 r->save_marks();
4173 return false;
4174 }
4175 };
4177 void G1CollectedHeap::save_marks() {
4178 if (ParallelGCThreads == 0) {
4179 SaveMarksClosure sm;
4180 heap_region_iterate(&sm);
4181 }
4182 // We do this even in the parallel case
4183 perm_gen()->save_marks();
4184 }
4186 void G1CollectedHeap::evacuate_collection_set() {
4187 set_evacuation_failed(false);
4189 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4190 concurrent_g1_refine()->set_use_cache(false);
4191 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4193 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4194 set_par_threads(n_workers);
4195 G1ParTask g1_par_task(this, n_workers, _task_queues);
4197 init_for_evac_failure(NULL);
4199 rem_set()->prepare_for_younger_refs_iterate(true);
4201 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4202 double start_par = os::elapsedTime();
4203 if (ParallelGCThreads > 0) {
4204 // The individual threads will set their evac-failure closures.
4205 StrongRootsScope srs(this);
4206 workers()->run_task(&g1_par_task);
4207 } else {
4208 StrongRootsScope srs(this);
4209 g1_par_task.work(0);
4210 }
4212 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4213 g1_policy()->record_par_time(par_time);
4214 set_par_threads(0);
4215 // Is this the right thing to do here? We don't save marks
4216 // on individual heap regions when we allocate from
4217 // them in parallel, so this seems like the correct place for this.
4218 retire_all_alloc_regions();
4219 {
4220 G1IsAliveClosure is_alive(this);
4221 G1KeepAliveClosure keep_alive(this);
4222 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4223 }
4224 release_gc_alloc_regions(false /* totally */);
4225 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4227 concurrent_g1_refine()->clear_hot_cache();
4228 concurrent_g1_refine()->set_use_cache(true);
4230 finalize_for_evac_failure();
4232 // Must do this before removing self-forwarding pointers, which clears
4233 // the per-region evac-failure flags.
4234 concurrent_mark()->complete_marking_in_collection_set();
4236 if (evacuation_failed()) {
4237 remove_self_forwarding_pointers();
4238 if (PrintGCDetails) {
4239 gclog_or_tty->print(" (evacuation failed)");
4240 } else if (PrintGC) {
4241 gclog_or_tty->print("--");
4242 }
4243 }
4245 if (G1DeferredRSUpdate) {
4246 RedirtyLoggedCardTableEntryFastClosure redirty;
4247 dirty_card_queue_set().set_closure(&redirty);
4248 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4250 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4251 dcq.merge_bufferlists(&dirty_card_queue_set());
4252 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4253 }
4254 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4255 }
4257 void G1CollectedHeap::free_region(HeapRegion* hr) {
4258 size_t pre_used = 0;
4259 size_t cleared_h_regions = 0;
4260 size_t freed_regions = 0;
4261 UncleanRegionList local_list;
4263 HeapWord* start = hr->bottom();
4264 HeapWord* end = hr->prev_top_at_mark_start();
4265 size_t used_bytes = hr->used();
4266 size_t live_bytes = hr->max_live_bytes();
4267 if (used_bytes > 0) {
4268 guarantee( live_bytes <= used_bytes, "invariant" );
4269 } else {
4270 guarantee( live_bytes == 0, "invariant" );
4271 }
4273 size_t garbage_bytes = used_bytes - live_bytes;
4274 if (garbage_bytes > 0)
4275 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4277 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4278 &local_list);
4279 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4280 &local_list);
4281 }
4283 void
4284 G1CollectedHeap::free_region_work(HeapRegion* hr,
4285 size_t& pre_used,
4286 size_t& cleared_h_regions,
4287 size_t& freed_regions,
4288 UncleanRegionList* list,
4289 bool par) {
4290 pre_used += hr->used();
4291 if (hr->isHumongous()) {
4292 assert(hr->startsHumongous(),
4293 "Only the start of a humongous region should be freed.");
4294 int ind = _hrs->find(hr);
4295 assert(ind != -1, "Should have an index.");
4296 // Clear the start region.
4297 hr->hr_clear(par, true /*clear_space*/);
4298 list->insert_before_head(hr);
4299 cleared_h_regions++;
4300 freed_regions++;
4301 // Clear any continued regions.
4302 ind++;
4303 while ((size_t)ind < n_regions()) {
4304 HeapRegion* hrc = _hrs->at(ind);
4305 if (!hrc->continuesHumongous()) break;
4306 // Otherwise, does continue the H region.
4307 assert(hrc->humongous_start_region() == hr, "Huh?");
4308 hrc->hr_clear(par, true /*clear_space*/);
4309 cleared_h_regions++;
4310 freed_regions++;
4311 list->insert_before_head(hrc);
4312 ind++;
4313 }
4314 } else {
4315 hr->hr_clear(par, true /*clear_space*/);
4316 list->insert_before_head(hr);
4317 freed_regions++;
4318 // If we're using clear2, this should not be enabled.
4319 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4320 }
4321 }
4323 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4324 size_t cleared_h_regions,
4325 size_t freed_regions,
4326 UncleanRegionList* list) {
4327 if (list != NULL && list->sz() > 0) {
4328 prepend_region_list_on_unclean_list(list);
4329 }
4330 // Acquire a lock, if we're parallel, to update possibly-shared
4331 // variables.
4332 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4333 {
4334 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4335 _summary_bytes_used -= pre_used;
4336 _num_humongous_regions -= (int) cleared_h_regions;
4337 _free_regions += freed_regions;
4338 }
4339 }
4342 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4343 while (list != NULL) {
4344 guarantee( list->is_young(), "invariant" );
4346 HeapWord* bottom = list->bottom();
4347 HeapWord* end = list->end();
4348 MemRegion mr(bottom, end);
4349 ct_bs->dirty(mr);
4351 list = list->get_next_young_region();
4352 }
4353 }
4356 class G1ParCleanupCTTask : public AbstractGangTask {
4357 CardTableModRefBS* _ct_bs;
4358 G1CollectedHeap* _g1h;
4359 HeapRegion* volatile _so_head;
4360 HeapRegion* volatile _su_head;
4361 public:
4362 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4363 G1CollectedHeap* g1h,
4364 HeapRegion* scan_only_list,
4365 HeapRegion* survivor_list) :
4366 AbstractGangTask("G1 Par Cleanup CT Task"),
4367 _ct_bs(ct_bs),
4368 _g1h(g1h),
4369 _so_head(scan_only_list),
4370 _su_head(survivor_list)
4371 { }
4373 void work(int i) {
4374 HeapRegion* r;
4375 while (r = _g1h->pop_dirty_cards_region()) {
4376 clear_cards(r);
4377 }
4378 // Redirty the cards of the scan-only and survivor regions.
4379 dirty_list(&this->_so_head);
4380 dirty_list(&this->_su_head);
4381 }
4383 void clear_cards(HeapRegion* r) {
4384 // Cards for Survivor and Scan-Only regions will be dirtied later.
4385 if (!r->is_scan_only() && !r->is_survivor()) {
4386 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4387 }
4388 }
4390 void dirty_list(HeapRegion* volatile * head_ptr) {
4391 HeapRegion* head;
4392 do {
4393 // Pop region off the list.
4394 head = *head_ptr;
4395 if (head != NULL) {
4396 HeapRegion* r = (HeapRegion*)
4397 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4398 if (r == head) {
4399 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4400 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4401 }
4402 }
4403 } while (*head_ptr != NULL);
4404 }
4405 };
4408 #ifndef PRODUCT
4409 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4410 CardTableModRefBS* _ct_bs;
4411 public:
4412 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4413 : _ct_bs(ct_bs)
4414 { }
4415 virtual bool doHeapRegion(HeapRegion* r)
4416 {
4417 MemRegion mr(r->bottom(), r->end());
4418 if (r->is_scan_only() || r->is_survivor()) {
4419 _ct_bs->verify_dirty_region(mr);
4420 } else {
4421 _ct_bs->verify_clean_region(mr);
4422 }
4423 return false;
4424 }
4425 };
4426 #endif
4428 void G1CollectedHeap::cleanUpCardTable() {
4429 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4430 double start = os::elapsedTime();
4432 // Iterate over the dirty cards region list.
4433 G1ParCleanupCTTask cleanup_task(ct_bs, this,
4434 _young_list->first_scan_only_region(),
4435 _young_list->first_survivor_region());
4436 if (ParallelGCThreads > 0) {
4437 set_par_threads(workers()->total_workers());
4438 workers()->run_task(&cleanup_task);
4439 set_par_threads(0);
4440 } else {
4441 while (_dirty_cards_region_list) {
4442 HeapRegion* r = _dirty_cards_region_list;
4443 cleanup_task.clear_cards(r);
4444 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4445 if (_dirty_cards_region_list == r) {
4446 // The last region.
4447 _dirty_cards_region_list = NULL;
4448 }
4449 r->set_next_dirty_cards_region(NULL);
4450 }
4451 // now, redirty the cards of the scan-only and survivor regions
4452 // (it seemed faster to do it this way, instead of iterating over
4453 // all regions and then clearing / dirtying as appropriate)
4454 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4455 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4456 }
4457 double elapsed = os::elapsedTime() - start;
4458 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4459 #ifndef PRODUCT
4460 if (G1VerifyCTCleanup || VerifyAfterGC) {
4461 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
4462 heap_region_iterate(&cleanup_verifier);
4463 }
4464 #endif
4465 }
4467 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4468 if (g1_policy()->should_do_collection_pause(word_size)) {
4469 do_collection_pause();
4470 }
4471 }
4473 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4474 double young_time_ms = 0.0;
4475 double non_young_time_ms = 0.0;
4477 G1CollectorPolicy* policy = g1_policy();
4479 double start_sec = os::elapsedTime();
4480 bool non_young = true;
4482 HeapRegion* cur = cs_head;
4483 int age_bound = -1;
4484 size_t rs_lengths = 0;
4486 while (cur != NULL) {
4487 if (non_young) {
4488 if (cur->is_young()) {
4489 double end_sec = os::elapsedTime();
4490 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4491 non_young_time_ms += elapsed_ms;
4493 start_sec = os::elapsedTime();
4494 non_young = false;
4495 }
4496 } else {
4497 if (!cur->is_on_free_list()) {
4498 double end_sec = os::elapsedTime();
4499 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4500 young_time_ms += elapsed_ms;
4502 start_sec = os::elapsedTime();
4503 non_young = true;
4504 }
4505 }
4507 rs_lengths += cur->rem_set()->occupied();
4509 HeapRegion* next = cur->next_in_collection_set();
4510 assert(cur->in_collection_set(), "bad CS");
4511 cur->set_next_in_collection_set(NULL);
4512 cur->set_in_collection_set(false);
4514 if (cur->is_young()) {
4515 int index = cur->young_index_in_cset();
4516 guarantee( index != -1, "invariant" );
4517 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4518 size_t words_survived = _surviving_young_words[index];
4519 cur->record_surv_words_in_group(words_survived);
4520 } else {
4521 int index = cur->young_index_in_cset();
4522 guarantee( index == -1, "invariant" );
4523 }
4525 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4526 (!cur->is_young() && cur->young_index_in_cset() == -1),
4527 "invariant" );
4529 if (!cur->evacuation_failed()) {
4530 // And the region is empty.
4531 assert(!cur->is_empty(),
4532 "Should not have empty regions in a CS.");
4533 free_region(cur);
4534 } else {
4535 guarantee( !cur->is_scan_only(), "should not be scan only" );
4536 cur->uninstall_surv_rate_group();
4537 if (cur->is_young())
4538 cur->set_young_index_in_cset(-1);
4539 cur->set_not_young();
4540 cur->set_evacuation_failed(false);
4541 }
4542 cur = next;
4543 }
4545 policy->record_max_rs_lengths(rs_lengths);
4546 policy->cset_regions_freed();
4548 double end_sec = os::elapsedTime();
4549 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4550 if (non_young)
4551 non_young_time_ms += elapsed_ms;
4552 else
4553 young_time_ms += elapsed_ms;
4555 policy->record_young_free_cset_time_ms(young_time_ms);
4556 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4557 }
4559 HeapRegion*
4560 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4561 assert(ZF_mon->owned_by_self(), "Precondition");
4562 HeapRegion* res = pop_unclean_region_list_locked();
4563 if (res != NULL) {
4564 assert(!res->continuesHumongous() &&
4565 res->zero_fill_state() != HeapRegion::Allocated,
4566 "Only free regions on unclean list.");
4567 if (zero_filled) {
4568 res->ensure_zero_filled_locked();
4569 res->set_zero_fill_allocated();
4570 }
4571 }
4572 return res;
4573 }
4575 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4576 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4577 return alloc_region_from_unclean_list_locked(zero_filled);
4578 }
4580 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4581 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4582 put_region_on_unclean_list_locked(r);
4583 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4584 }
4586 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4587 MutexLockerEx x(Cleanup_mon);
4588 set_unclean_regions_coming_locked(b);
4589 }
4591 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4592 assert(Cleanup_mon->owned_by_self(), "Precondition");
4593 _unclean_regions_coming = b;
4594 // Wake up mutator threads that might be waiting for completeCleanup to
4595 // finish.
4596 if (!b) Cleanup_mon->notify_all();
4597 }
4599 void G1CollectedHeap::wait_for_cleanup_complete() {
4600 MutexLockerEx x(Cleanup_mon);
4601 wait_for_cleanup_complete_locked();
4602 }
4604 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4605 assert(Cleanup_mon->owned_by_self(), "precondition");
4606 while (_unclean_regions_coming) {
4607 Cleanup_mon->wait();
4608 }
4609 }
4611 void
4612 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4613 assert(ZF_mon->owned_by_self(), "precondition.");
4614 _unclean_region_list.insert_before_head(r);
4615 }
4617 void
4618 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4619 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4620 prepend_region_list_on_unclean_list_locked(list);
4621 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4622 }
4624 void
4625 G1CollectedHeap::
4626 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4627 assert(ZF_mon->owned_by_self(), "precondition.");
4628 _unclean_region_list.prepend_list(list);
4629 }
4631 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4632 assert(ZF_mon->owned_by_self(), "precondition.");
4633 HeapRegion* res = _unclean_region_list.pop();
4634 if (res != NULL) {
4635 // Inform ZF thread that there's a new unclean head.
4636 if (_unclean_region_list.hd() != NULL && should_zf())
4637 ZF_mon->notify_all();
4638 }
4639 return res;
4640 }
4642 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4643 assert(ZF_mon->owned_by_self(), "precondition.");
4644 return _unclean_region_list.hd();
4645 }
4648 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4649 assert(ZF_mon->owned_by_self(), "Precondition");
4650 HeapRegion* r = peek_unclean_region_list_locked();
4651 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4652 // Result of below must be equal to "r", since we hold the lock.
4653 (void)pop_unclean_region_list_locked();
4654 put_free_region_on_list_locked(r);
4655 return true;
4656 } else {
4657 return false;
4658 }
4659 }
4661 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4662 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4663 return move_cleaned_region_to_free_list_locked();
4664 }
4667 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4668 assert(ZF_mon->owned_by_self(), "precondition.");
4669 assert(_free_region_list_size == free_region_list_length(), "Inv");
4670 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4671 "Regions on free list must be zero filled");
4672 assert(!r->isHumongous(), "Must not be humongous.");
4673 assert(r->is_empty(), "Better be empty");
4674 assert(!r->is_on_free_list(),
4675 "Better not already be on free list");
4676 assert(!r->is_on_unclean_list(),
4677 "Better not already be on unclean list");
4678 r->set_on_free_list(true);
4679 r->set_next_on_free_list(_free_region_list);
4680 _free_region_list = r;
4681 _free_region_list_size++;
4682 assert(_free_region_list_size == free_region_list_length(), "Inv");
4683 }
4685 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4686 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4687 put_free_region_on_list_locked(r);
4688 }
4690 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4691 assert(ZF_mon->owned_by_self(), "precondition.");
4692 assert(_free_region_list_size == free_region_list_length(), "Inv");
4693 HeapRegion* res = _free_region_list;
4694 if (res != NULL) {
4695 _free_region_list = res->next_from_free_list();
4696 _free_region_list_size--;
4697 res->set_on_free_list(false);
4698 res->set_next_on_free_list(NULL);
4699 assert(_free_region_list_size == free_region_list_length(), "Inv");
4700 }
4701 return res;
4702 }
4705 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4706 // By self, or on behalf of self.
4707 assert(Heap_lock->is_locked(), "Precondition");
4708 HeapRegion* res = NULL;
4709 bool first = true;
4710 while (res == NULL) {
4711 if (zero_filled || !first) {
4712 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4713 res = pop_free_region_list_locked();
4714 if (res != NULL) {
4715 assert(!res->zero_fill_is_allocated(),
4716 "No allocated regions on free list.");
4717 res->set_zero_fill_allocated();
4718 } else if (!first) {
4719 break; // We tried both, time to return NULL.
4720 }
4721 }
4723 if (res == NULL) {
4724 res = alloc_region_from_unclean_list(zero_filled);
4725 }
4726 assert(res == NULL ||
4727 !zero_filled ||
4728 res->zero_fill_is_allocated(),
4729 "We must have allocated the region we're returning");
4730 first = false;
4731 }
4732 return res;
4733 }
4735 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4736 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4737 {
4738 HeapRegion* prev = NULL;
4739 HeapRegion* cur = _unclean_region_list.hd();
4740 while (cur != NULL) {
4741 HeapRegion* next = cur->next_from_unclean_list();
4742 if (cur->zero_fill_is_allocated()) {
4743 // Remove from the list.
4744 if (prev == NULL) {
4745 (void)_unclean_region_list.pop();
4746 } else {
4747 _unclean_region_list.delete_after(prev);
4748 }
4749 cur->set_on_unclean_list(false);
4750 cur->set_next_on_unclean_list(NULL);
4751 } else {
4752 prev = cur;
4753 }
4754 cur = next;
4755 }
4756 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4757 "Inv");
4758 }
4760 {
4761 HeapRegion* prev = NULL;
4762 HeapRegion* cur = _free_region_list;
4763 while (cur != NULL) {
4764 HeapRegion* next = cur->next_from_free_list();
4765 if (cur->zero_fill_is_allocated()) {
4766 // Remove from the list.
4767 if (prev == NULL) {
4768 _free_region_list = cur->next_from_free_list();
4769 } else {
4770 prev->set_next_on_free_list(cur->next_from_free_list());
4771 }
4772 cur->set_on_free_list(false);
4773 cur->set_next_on_free_list(NULL);
4774 _free_region_list_size--;
4775 } else {
4776 prev = cur;
4777 }
4778 cur = next;
4779 }
4780 assert(_free_region_list_size == free_region_list_length(), "Inv");
4781 }
4782 }
4784 bool G1CollectedHeap::verify_region_lists() {
4785 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4786 return verify_region_lists_locked();
4787 }
4789 bool G1CollectedHeap::verify_region_lists_locked() {
4790 HeapRegion* unclean = _unclean_region_list.hd();
4791 while (unclean != NULL) {
4792 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4793 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4794 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4795 "Everything else is possible.");
4796 unclean = unclean->next_from_unclean_list();
4797 }
4798 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4800 HeapRegion* free_r = _free_region_list;
4801 while (free_r != NULL) {
4802 assert(free_r->is_on_free_list(), "Well, it is!");
4803 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4804 switch (free_r->zero_fill_state()) {
4805 case HeapRegion::NotZeroFilled:
4806 case HeapRegion::ZeroFilling:
4807 guarantee(false, "Should not be on free list.");
4808 break;
4809 default:
4810 // Everything else is possible.
4811 break;
4812 }
4813 free_r = free_r->next_from_free_list();
4814 }
4815 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4816 // If we didn't do an assertion...
4817 return true;
4818 }
4820 size_t G1CollectedHeap::free_region_list_length() {
4821 assert(ZF_mon->owned_by_self(), "precondition.");
4822 size_t len = 0;
4823 HeapRegion* cur = _free_region_list;
4824 while (cur != NULL) {
4825 len++;
4826 cur = cur->next_from_free_list();
4827 }
4828 return len;
4829 }
4831 size_t G1CollectedHeap::unclean_region_list_length() {
4832 assert(ZF_mon->owned_by_self(), "precondition.");
4833 return _unclean_region_list.length();
4834 }
4836 size_t G1CollectedHeap::n_regions() {
4837 return _hrs->length();
4838 }
4840 size_t G1CollectedHeap::max_regions() {
4841 return
4842 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4843 HeapRegion::GrainBytes;
4844 }
4846 size_t G1CollectedHeap::free_regions() {
4847 /* Possibly-expensive assert.
4848 assert(_free_regions == count_free_regions(),
4849 "_free_regions is off.");
4850 */
4851 return _free_regions;
4852 }
4854 bool G1CollectedHeap::should_zf() {
4855 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4856 }
4858 class RegionCounter: public HeapRegionClosure {
4859 size_t _n;
4860 public:
4861 RegionCounter() : _n(0) {}
4862 bool doHeapRegion(HeapRegion* r) {
4863 if (r->is_empty()) {
4864 assert(!r->isHumongous(), "H regions should not be empty.");
4865 _n++;
4866 }
4867 return false;
4868 }
4869 int res() { return (int) _n; }
4870 };
4872 size_t G1CollectedHeap::count_free_regions() {
4873 RegionCounter rc;
4874 heap_region_iterate(&rc);
4875 size_t n = rc.res();
4876 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4877 n--;
4878 return n;
4879 }
4881 size_t G1CollectedHeap::count_free_regions_list() {
4882 size_t n = 0;
4883 size_t o = 0;
4884 ZF_mon->lock_without_safepoint_check();
4885 HeapRegion* cur = _free_region_list;
4886 while (cur != NULL) {
4887 cur = cur->next_from_free_list();
4888 n++;
4889 }
4890 size_t m = unclean_region_list_length();
4891 ZF_mon->unlock();
4892 return n + m;
4893 }
4895 bool G1CollectedHeap::should_set_young_locked() {
4896 assert(heap_lock_held_for_gc(),
4897 "the heap lock should already be held by or for this thread");
4898 return (g1_policy()->in_young_gc_mode() &&
4899 g1_policy()->should_add_next_region_to_young_list());
4900 }
4902 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4903 assert(heap_lock_held_for_gc(),
4904 "the heap lock should already be held by or for this thread");
4905 _young_list->push_region(hr);
4906 g1_policy()->set_region_short_lived(hr);
4907 }
4909 class NoYoungRegionsClosure: public HeapRegionClosure {
4910 private:
4911 bool _success;
4912 public:
4913 NoYoungRegionsClosure() : _success(true) { }
4914 bool doHeapRegion(HeapRegion* r) {
4915 if (r->is_young()) {
4916 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
4917 r->bottom(), r->end());
4918 _success = false;
4919 }
4920 return false;
4921 }
4922 bool success() { return _success; }
4923 };
4925 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
4926 bool check_sample) {
4927 bool ret = true;
4929 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
4930 if (!ignore_scan_only_list) {
4931 NoYoungRegionsClosure closure;
4932 heap_region_iterate(&closure);
4933 ret = ret && closure.success();
4934 }
4936 return ret;
4937 }
4939 void G1CollectedHeap::empty_young_list() {
4940 assert(heap_lock_held_for_gc(),
4941 "the heap lock should already be held by or for this thread");
4942 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
4944 _young_list->empty_list();
4945 }
4947 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
4948 bool no_allocs = true;
4949 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
4950 HeapRegion* r = _gc_alloc_regions[ap];
4951 no_allocs = r == NULL || r->saved_mark_at_top();
4952 }
4953 return no_allocs;
4954 }
4956 void G1CollectedHeap::retire_all_alloc_regions() {
4957 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4958 HeapRegion* r = _gc_alloc_regions[ap];
4959 if (r != NULL) {
4960 // Check for aliases.
4961 bool has_processed_alias = false;
4962 for (int i = 0; i < ap; ++i) {
4963 if (_gc_alloc_regions[i] == r) {
4964 has_processed_alias = true;
4965 break;
4966 }
4967 }
4968 if (!has_processed_alias) {
4969 retire_alloc_region(r, false /* par */);
4970 }
4971 }
4972 }
4973 }
4976 // Done at the start of full GC.
4977 void G1CollectedHeap::tear_down_region_lists() {
4978 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4979 while (pop_unclean_region_list_locked() != NULL) ;
4980 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
4981 "Postconditions of loop.")
4982 while (pop_free_region_list_locked() != NULL) ;
4983 assert(_free_region_list == NULL, "Postcondition of loop.");
4984 if (_free_region_list_size != 0) {
4985 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
4986 print_on(gclog_or_tty, true /* extended */);
4987 }
4988 assert(_free_region_list_size == 0, "Postconditions of loop.");
4989 }
4992 class RegionResetter: public HeapRegionClosure {
4993 G1CollectedHeap* _g1;
4994 int _n;
4995 public:
4996 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4997 bool doHeapRegion(HeapRegion* r) {
4998 if (r->continuesHumongous()) return false;
4999 if (r->top() > r->bottom()) {
5000 if (r->top() < r->end()) {
5001 Copy::fill_to_words(r->top(),
5002 pointer_delta(r->end(), r->top()));
5003 }
5004 r->set_zero_fill_allocated();
5005 } else {
5006 assert(r->is_empty(), "tautology");
5007 _n++;
5008 switch (r->zero_fill_state()) {
5009 case HeapRegion::NotZeroFilled:
5010 case HeapRegion::ZeroFilling:
5011 _g1->put_region_on_unclean_list_locked(r);
5012 break;
5013 case HeapRegion::Allocated:
5014 r->set_zero_fill_complete();
5015 // no break; go on to put on free list.
5016 case HeapRegion::ZeroFilled:
5017 _g1->put_free_region_on_list_locked(r);
5018 break;
5019 }
5020 }
5021 return false;
5022 }
5024 int getFreeRegionCount() {return _n;}
5025 };
5027 // Done at the end of full GC.
5028 void G1CollectedHeap::rebuild_region_lists() {
5029 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5030 // This needs to go at the end of the full GC.
5031 RegionResetter rs;
5032 heap_region_iterate(&rs);
5033 _free_regions = rs.getFreeRegionCount();
5034 // Tell the ZF thread it may have work to do.
5035 if (should_zf()) ZF_mon->notify_all();
5036 }
5038 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5039 G1CollectedHeap* _g1;
5040 int _n;
5041 public:
5042 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5043 bool doHeapRegion(HeapRegion* r) {
5044 if (r->continuesHumongous()) return false;
5045 if (r->top() > r->bottom()) {
5046 // There are assertions in "set_zero_fill_needed()" below that
5047 // require top() == bottom(), so this is technically illegal.
5048 // We'll skirt the law here, by making that true temporarily.
5049 DEBUG_ONLY(HeapWord* save_top = r->top();
5050 r->set_top(r->bottom()));
5051 r->set_zero_fill_needed();
5052 DEBUG_ONLY(r->set_top(save_top));
5053 }
5054 return false;
5055 }
5056 };
5058 // Done at the start of full GC.
5059 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5060 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5061 // This needs to go at the end of the full GC.
5062 UsedRegionsNeedZeroFillSetter rs;
5063 heap_region_iterate(&rs);
5064 }
5066 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5067 _refine_cte_cl->set_concurrent(concurrent);
5068 }
5070 #ifndef PRODUCT
5072 class PrintHeapRegionClosure: public HeapRegionClosure {
5073 public:
5074 bool doHeapRegion(HeapRegion *r) {
5075 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5076 if (r != NULL) {
5077 if (r->is_on_free_list())
5078 gclog_or_tty->print("Free ");
5079 if (r->is_young())
5080 gclog_or_tty->print("Young ");
5081 if (r->isHumongous())
5082 gclog_or_tty->print("Is Humongous ");
5083 r->print();
5084 }
5085 return false;
5086 }
5087 };
5089 class SortHeapRegionClosure : public HeapRegionClosure {
5090 size_t young_regions,free_regions, unclean_regions;
5091 size_t hum_regions, count;
5092 size_t unaccounted, cur_unclean, cur_alloc;
5093 size_t total_free;
5094 HeapRegion* cur;
5095 public:
5096 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5097 free_regions(0), unclean_regions(0),
5098 hum_regions(0),
5099 count(0), unaccounted(0),
5100 cur_alloc(0), total_free(0)
5101 {}
5102 bool doHeapRegion(HeapRegion *r) {
5103 count++;
5104 if (r->is_on_free_list()) free_regions++;
5105 else if (r->is_on_unclean_list()) unclean_regions++;
5106 else if (r->isHumongous()) hum_regions++;
5107 else if (r->is_young()) young_regions++;
5108 else if (r == cur) cur_alloc++;
5109 else unaccounted++;
5110 return false;
5111 }
5112 void print() {
5113 total_free = free_regions + unclean_regions;
5114 gclog_or_tty->print("%d regions\n", count);
5115 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5116 total_free, free_regions, unclean_regions);
5117 gclog_or_tty->print("%d humongous %d young\n",
5118 hum_regions, young_regions);
5119 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5120 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5121 }
5122 };
5124 void G1CollectedHeap::print_region_counts() {
5125 SortHeapRegionClosure sc(_cur_alloc_region);
5126 PrintHeapRegionClosure cl;
5127 heap_region_iterate(&cl);
5128 heap_region_iterate(&sc);
5129 sc.print();
5130 print_region_accounting_info();
5131 };
5133 bool G1CollectedHeap::regions_accounted_for() {
5134 // TODO: regions accounting for young/survivor/tenured
5135 return true;
5136 }
5138 bool G1CollectedHeap::print_region_accounting_info() {
5139 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5140 free_regions(),
5141 count_free_regions(), count_free_regions_list(),
5142 _free_region_list_size, _unclean_region_list.sz());
5143 gclog_or_tty->print_cr("cur_alloc: %d.",
5144 (_cur_alloc_region == NULL ? 0 : 1));
5145 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5147 // TODO: check regions accounting for young/survivor/tenured
5148 return true;
5149 }
5151 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5152 HeapRegion* hr = heap_region_containing(p);
5153 if (hr == NULL) {
5154 return is_in_permanent(p);
5155 } else {
5156 return hr->is_in(p);
5157 }
5158 }
5159 #endif // !PRODUCT
5161 void G1CollectedHeap::g1_unimplemented() {
5162 // Unimplemented();
5163 }