Wed, 30 Sep 2009 14:50:51 -0400
6890137: G1: revamp reachable object dump
Summary: Revamp the reachable object dump debugging facility.
Reviewed-by: jmasa, apetrusenko
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 double start = os::elapsedTime();
932 g1_policy()->record_full_collection_start();
934 gc_prologue(true);
935 increment_total_collections(true /* full gc */);
937 size_t g1h_prev_used = used();
938 assert(used() == recalculate_used(), "Should be equal");
940 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
941 HandleMark hm; // Discard invalid handles created during verification
942 prepare_for_verify();
943 gclog_or_tty->print(" VerifyBeforeGC:");
944 Universe::verify(true);
945 }
946 assert(regions_accounted_for(), "Region leakage!");
948 COMPILER2_PRESENT(DerivedPointerTable::clear());
950 // We want to discover references, but not process them yet.
951 // This mode is disabled in
952 // instanceRefKlass::process_discovered_references if the
953 // generation does some collection work, or
954 // instanceRefKlass::enqueue_discovered_references if the
955 // generation returns without doing any work.
956 ref_processor()->disable_discovery();
957 ref_processor()->abandon_partial_discovery();
958 ref_processor()->verify_no_references_recorded();
960 // Abandon current iterations of concurrent marking and concurrent
961 // refinement, if any are in progress.
962 concurrent_mark()->abort();
964 // Make sure we'll choose a new allocation region afterwards.
965 abandon_cur_alloc_region();
966 abandon_gc_alloc_regions();
967 assert(_cur_alloc_region == NULL, "Invariant.");
968 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
969 tear_down_region_lists();
970 set_used_regions_to_need_zero_fill();
971 if (g1_policy()->in_young_gc_mode()) {
972 empty_young_list();
973 g1_policy()->set_full_young_gcs(true);
974 }
976 // Temporarily make reference _discovery_ single threaded (non-MT).
977 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
979 // Temporarily make refs discovery atomic
980 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
982 // Temporarily clear _is_alive_non_header
983 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
985 ref_processor()->enable_discovery();
986 ref_processor()->setup_policy(clear_all_soft_refs);
988 // Do collection work
989 {
990 HandleMark hm; // Discard invalid handles created during gc
991 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
992 }
993 // Because freeing humongous regions may have added some unclean
994 // regions, it is necessary to tear down again before rebuilding.
995 tear_down_region_lists();
996 rebuild_region_lists();
998 _summary_bytes_used = recalculate_used();
1000 ref_processor()->enqueue_discovered_references();
1002 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1004 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1005 HandleMark hm; // Discard invalid handles created during verification
1006 gclog_or_tty->print(" VerifyAfterGC:");
1007 prepare_for_verify();
1008 Universe::verify(false);
1009 }
1010 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1012 reset_gc_time_stamp();
1013 // Since everything potentially moved, we will clear all remembered
1014 // sets, and clear all cards. Later we will rebuild remebered
1015 // sets. We will also reset the GC time stamps of the regions.
1016 PostMCRemSetClearClosure rs_clear(mr_bs());
1017 heap_region_iterate(&rs_clear);
1019 // Resize the heap if necessary.
1020 resize_if_necessary_after_full_collection(full ? 0 : word_size);
1022 if (_cg1r->use_cache()) {
1023 _cg1r->clear_and_record_card_counts();
1024 _cg1r->clear_hot_cache();
1025 }
1027 // Rebuild remembered sets of all regions.
1028 if (ParallelGCThreads > 0) {
1029 ParRebuildRSTask rebuild_rs_task(this);
1030 assert(check_heap_region_claim_values(
1031 HeapRegion::InitialClaimValue), "sanity check");
1032 set_par_threads(workers()->total_workers());
1033 workers()->run_task(&rebuild_rs_task);
1034 set_par_threads(0);
1035 assert(check_heap_region_claim_values(
1036 HeapRegion::RebuildRSClaimValue), "sanity check");
1037 reset_heap_region_claim_values();
1038 } else {
1039 RebuildRSOutOfRegionClosure rebuild_rs(this);
1040 heap_region_iterate(&rebuild_rs);
1041 }
1043 if (PrintGC) {
1044 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1045 }
1047 if (true) { // FIXME
1048 // Ask the permanent generation to adjust size for full collections
1049 perm()->compute_new_size();
1050 }
1052 double end = os::elapsedTime();
1053 g1_policy()->record_full_collection_end();
1055 #ifdef TRACESPINNING
1056 ParallelTaskTerminator::print_termination_counts();
1057 #endif
1059 gc_epilogue(true);
1061 // Discard all rset updates
1062 JavaThread::dirty_card_queue_set().abandon_logs();
1063 assert(!G1DeferredRSUpdate
1064 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1065 assert(regions_accounted_for(), "Region leakage!");
1066 }
1068 if (g1_policy()->in_young_gc_mode()) {
1069 _young_list->reset_sampled_info();
1070 assert( check_young_list_empty(false, false),
1071 "young list should be empty at this point");
1072 }
1074 if (PrintHeapAtGC) {
1075 Universe::print_heap_after_gc();
1076 }
1077 }
1079 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1080 do_collection(true, clear_all_soft_refs, 0);
1081 }
1083 // This code is mostly copied from TenuredGeneration.
1084 void
1085 G1CollectedHeap::
1086 resize_if_necessary_after_full_collection(size_t word_size) {
1087 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1089 // Include the current allocation, if any, and bytes that will be
1090 // pre-allocated to support collections, as "used".
1091 const size_t used_after_gc = used();
1092 const size_t capacity_after_gc = capacity();
1093 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1095 // We don't have floating point command-line arguments
1096 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1097 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1098 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1099 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1101 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1102 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1104 // Don't shrink less than the initial size.
1105 minimum_desired_capacity =
1106 MAX2(minimum_desired_capacity,
1107 collector_policy()->initial_heap_byte_size());
1108 maximum_desired_capacity =
1109 MAX2(maximum_desired_capacity,
1110 collector_policy()->initial_heap_byte_size());
1112 // We are failing here because minimum_desired_capacity is
1113 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1114 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1116 if (PrintGC && Verbose) {
1117 const double free_percentage = ((double)free_after_gc) / capacity();
1118 gclog_or_tty->print_cr("Computing new size after full GC ");
1119 gclog_or_tty->print_cr(" "
1120 " minimum_free_percentage: %6.2f",
1121 minimum_free_percentage);
1122 gclog_or_tty->print_cr(" "
1123 " maximum_free_percentage: %6.2f",
1124 maximum_free_percentage);
1125 gclog_or_tty->print_cr(" "
1126 " capacity: %6.1fK"
1127 " minimum_desired_capacity: %6.1fK"
1128 " maximum_desired_capacity: %6.1fK",
1129 capacity() / (double) K,
1130 minimum_desired_capacity / (double) K,
1131 maximum_desired_capacity / (double) K);
1132 gclog_or_tty->print_cr(" "
1133 " free_after_gc : %6.1fK"
1134 " used_after_gc : %6.1fK",
1135 free_after_gc / (double) K,
1136 used_after_gc / (double) K);
1137 gclog_or_tty->print_cr(" "
1138 " free_percentage: %6.2f",
1139 free_percentage);
1140 }
1141 if (capacity() < minimum_desired_capacity) {
1142 // Don't expand unless it's significant
1143 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1144 expand(expand_bytes);
1145 if (PrintGC && Verbose) {
1146 gclog_or_tty->print_cr(" expanding:"
1147 " minimum_desired_capacity: %6.1fK"
1148 " expand_bytes: %6.1fK",
1149 minimum_desired_capacity / (double) K,
1150 expand_bytes / (double) K);
1151 }
1153 // No expansion, now see if we want to shrink
1154 } else if (capacity() > maximum_desired_capacity) {
1155 // Capacity too large, compute shrinking size
1156 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1157 shrink(shrink_bytes);
1158 if (PrintGC && Verbose) {
1159 gclog_or_tty->print_cr(" "
1160 " shrinking:"
1161 " initSize: %.1fK"
1162 " maximum_desired_capacity: %.1fK",
1163 collector_policy()->initial_heap_byte_size() / (double) K,
1164 maximum_desired_capacity / (double) K);
1165 gclog_or_tty->print_cr(" "
1166 " shrink_bytes: %.1fK",
1167 shrink_bytes / (double) K);
1168 }
1169 }
1170 }
1173 HeapWord*
1174 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1175 HeapWord* result = NULL;
1177 // In a G1 heap, we're supposed to keep allocation from failing by
1178 // incremental pauses. Therefore, at least for now, we'll favor
1179 // expansion over collection. (This might change in the future if we can
1180 // do something smarter than full collection to satisfy a failed alloc.)
1182 result = expand_and_allocate(word_size);
1183 if (result != NULL) {
1184 assert(is_in(result), "result not in heap");
1185 return result;
1186 }
1188 // OK, I guess we have to try collection.
1190 do_collection(false, false, word_size);
1192 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1194 if (result != NULL) {
1195 assert(is_in(result), "result not in heap");
1196 return result;
1197 }
1199 // Try collecting soft references.
1200 do_collection(false, true, word_size);
1201 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1202 if (result != NULL) {
1203 assert(is_in(result), "result not in heap");
1204 return result;
1205 }
1207 // What else? We might try synchronous finalization later. If the total
1208 // space available is large enough for the allocation, then a more
1209 // complete compaction phase than we've tried so far might be
1210 // appropriate.
1211 return NULL;
1212 }
1214 // Attempting to expand the heap sufficiently
1215 // to support an allocation of the given "word_size". If
1216 // successful, perform the allocation and return the address of the
1217 // allocated block, or else "NULL".
1219 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1220 size_t expand_bytes = word_size * HeapWordSize;
1221 if (expand_bytes < MinHeapDeltaBytes) {
1222 expand_bytes = MinHeapDeltaBytes;
1223 }
1224 expand(expand_bytes);
1225 assert(regions_accounted_for(), "Region leakage!");
1226 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1227 return result;
1228 }
1230 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1231 size_t pre_used = 0;
1232 size_t cleared_h_regions = 0;
1233 size_t freed_regions = 0;
1234 UncleanRegionList local_list;
1235 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1236 freed_regions, &local_list);
1238 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1239 &local_list);
1240 return pre_used;
1241 }
1243 void
1244 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1245 size_t& pre_used,
1246 size_t& cleared_h,
1247 size_t& freed_regions,
1248 UncleanRegionList* list,
1249 bool par) {
1250 assert(!hr->continuesHumongous(), "should have filtered these out");
1251 size_t res = 0;
1252 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1253 !hr->is_young()) {
1254 if (G1PolicyVerbose > 0)
1255 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1256 " during cleanup", hr, hr->used());
1257 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1258 }
1259 }
1261 // FIXME: both this and shrink could probably be more efficient by
1262 // doing one "VirtualSpace::expand_by" call rather than several.
1263 void G1CollectedHeap::expand(size_t expand_bytes) {
1264 size_t old_mem_size = _g1_storage.committed_size();
1265 // We expand by a minimum of 1K.
1266 expand_bytes = MAX2(expand_bytes, (size_t)K);
1267 size_t aligned_expand_bytes =
1268 ReservedSpace::page_align_size_up(expand_bytes);
1269 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1270 HeapRegion::GrainBytes);
1271 expand_bytes = aligned_expand_bytes;
1272 while (expand_bytes > 0) {
1273 HeapWord* base = (HeapWord*)_g1_storage.high();
1274 // Commit more storage.
1275 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1276 if (!successful) {
1277 expand_bytes = 0;
1278 } else {
1279 expand_bytes -= HeapRegion::GrainBytes;
1280 // Expand the committed region.
1281 HeapWord* high = (HeapWord*) _g1_storage.high();
1282 _g1_committed.set_end(high);
1283 // Create a new HeapRegion.
1284 MemRegion mr(base, high);
1285 bool is_zeroed = !_g1_max_committed.contains(base);
1286 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1288 // Now update max_committed if necessary.
1289 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1291 // Add it to the HeapRegionSeq.
1292 _hrs->insert(hr);
1293 // Set the zero-fill state, according to whether it's already
1294 // zeroed.
1295 {
1296 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1297 if (is_zeroed) {
1298 hr->set_zero_fill_complete();
1299 put_free_region_on_list_locked(hr);
1300 } else {
1301 hr->set_zero_fill_needed();
1302 put_region_on_unclean_list_locked(hr);
1303 }
1304 }
1305 _free_regions++;
1306 // And we used up an expansion region to create it.
1307 _expansion_regions--;
1308 // Tell the cardtable about it.
1309 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1310 // And the offset table as well.
1311 _bot_shared->resize(_g1_committed.word_size());
1312 }
1313 }
1314 if (Verbose && PrintGC) {
1315 size_t new_mem_size = _g1_storage.committed_size();
1316 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1317 old_mem_size/K, aligned_expand_bytes/K,
1318 new_mem_size/K);
1319 }
1320 }
1322 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1323 {
1324 size_t old_mem_size = _g1_storage.committed_size();
1325 size_t aligned_shrink_bytes =
1326 ReservedSpace::page_align_size_down(shrink_bytes);
1327 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1328 HeapRegion::GrainBytes);
1329 size_t num_regions_deleted = 0;
1330 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1332 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1333 if (mr.byte_size() > 0)
1334 _g1_storage.shrink_by(mr.byte_size());
1335 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1337 _g1_committed.set_end(mr.start());
1338 _free_regions -= num_regions_deleted;
1339 _expansion_regions += num_regions_deleted;
1341 // Tell the cardtable about it.
1342 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1344 // And the offset table as well.
1345 _bot_shared->resize(_g1_committed.word_size());
1347 HeapRegionRemSet::shrink_heap(n_regions());
1349 if (Verbose && PrintGC) {
1350 size_t new_mem_size = _g1_storage.committed_size();
1351 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1352 old_mem_size/K, aligned_shrink_bytes/K,
1353 new_mem_size/K);
1354 }
1355 }
1357 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1358 release_gc_alloc_regions(true /* totally */);
1359 tear_down_region_lists(); // We will rebuild them in a moment.
1360 shrink_helper(shrink_bytes);
1361 rebuild_region_lists();
1362 }
1364 // Public methods.
1366 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1367 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1368 #endif // _MSC_VER
1371 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1372 SharedHeap(policy_),
1373 _g1_policy(policy_),
1374 _ref_processor(NULL),
1375 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1376 _bot_shared(NULL),
1377 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1378 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1379 _evac_failure_scan_stack(NULL) ,
1380 _mark_in_progress(false),
1381 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1382 _cur_alloc_region(NULL),
1383 _refine_cte_cl(NULL),
1384 _free_region_list(NULL), _free_region_list_size(0),
1385 _free_regions(0),
1386 _full_collection(false),
1387 _unclean_region_list(),
1388 _unclean_regions_coming(false),
1389 _young_list(new YoungList(this)),
1390 _gc_time_stamp(0),
1391 _surviving_young_words(NULL),
1392 _in_cset_fast_test(NULL),
1393 _in_cset_fast_test_base(NULL),
1394 _dirty_cards_region_list(NULL) {
1395 _g1h = this; // To catch bugs.
1396 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1397 vm_exit_during_initialization("Failed necessary allocation.");
1398 }
1400 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1402 int n_queues = MAX2((int)ParallelGCThreads, 1);
1403 _task_queues = new RefToScanQueueSet(n_queues);
1405 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1406 assert(n_rem_sets > 0, "Invariant.");
1408 HeapRegionRemSetIterator** iter_arr =
1409 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1410 for (int i = 0; i < n_queues; i++) {
1411 iter_arr[i] = new HeapRegionRemSetIterator();
1412 }
1413 _rem_set_iterator = iter_arr;
1415 for (int i = 0; i < n_queues; i++) {
1416 RefToScanQueue* q = new RefToScanQueue();
1417 q->initialize();
1418 _task_queues->register_queue(i, q);
1419 }
1421 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1422 _gc_alloc_regions[ap] = NULL;
1423 _gc_alloc_region_counts[ap] = 0;
1424 _retained_gc_alloc_regions[ap] = NULL;
1425 // by default, we do not retain a GC alloc region for each ap;
1426 // we'll override this, when appropriate, below
1427 _retain_gc_alloc_region[ap] = false;
1428 }
1430 // We will try to remember the last half-full tenured region we
1431 // allocated to at the end of a collection so that we can re-use it
1432 // during the next collection.
1433 _retain_gc_alloc_region[GCAllocForTenured] = true;
1435 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1436 }
1438 jint G1CollectedHeap::initialize() {
1439 os::enable_vtime();
1441 // Necessary to satisfy locking discipline assertions.
1443 MutexLocker x(Heap_lock);
1445 // While there are no constraints in the GC code that HeapWordSize
1446 // be any particular value, there are multiple other areas in the
1447 // system which believe this to be true (e.g. oop->object_size in some
1448 // cases incorrectly returns the size in wordSize units rather than
1449 // HeapWordSize).
1450 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1452 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1453 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1455 // Ensure that the sizes are properly aligned.
1456 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1457 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1459 // We allocate this in any case, but only do no work if the command line
1460 // param is off.
1461 _cg1r = new ConcurrentG1Refine();
1463 // Reserve the maximum.
1464 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1465 // Includes the perm-gen.
1467 const size_t total_reserved = max_byte_size + pgs->max_size();
1468 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1470 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1471 HeapRegion::GrainBytes,
1472 false /*ism*/, addr);
1474 if (UseCompressedOops) {
1475 if (addr != NULL && !heap_rs.is_reserved()) {
1476 // Failed to reserve at specified address - the requested memory
1477 // region is taken already, for example, by 'java' launcher.
1478 // Try again to reserver heap higher.
1479 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1480 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1481 false /*ism*/, addr);
1482 if (addr != NULL && !heap_rs0.is_reserved()) {
1483 // Failed to reserve at specified address again - give up.
1484 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1485 assert(addr == NULL, "");
1486 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1487 false /*ism*/, addr);
1488 heap_rs = heap_rs1;
1489 } else {
1490 heap_rs = heap_rs0;
1491 }
1492 }
1493 }
1495 if (!heap_rs.is_reserved()) {
1496 vm_exit_during_initialization("Could not reserve enough space for object heap");
1497 return JNI_ENOMEM;
1498 }
1500 // It is important to do this in a way such that concurrent readers can't
1501 // temporarily think somethings in the heap. (I've actually seen this
1502 // happen in asserts: DLD.)
1503 _reserved.set_word_size(0);
1504 _reserved.set_start((HeapWord*)heap_rs.base());
1505 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1507 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1509 _num_humongous_regions = 0;
1511 // Create the gen rem set (and barrier set) for the entire reserved region.
1512 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1513 set_barrier_set(rem_set()->bs());
1514 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1515 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1516 } else {
1517 vm_exit_during_initialization("G1 requires a mod ref bs.");
1518 return JNI_ENOMEM;
1519 }
1521 // Also create a G1 rem set.
1522 if (G1UseHRIntoRS) {
1523 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1524 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1525 } else {
1526 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1527 return JNI_ENOMEM;
1528 }
1529 } else {
1530 _g1_rem_set = new StupidG1RemSet(this);
1531 }
1533 // Carve out the G1 part of the heap.
1535 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1536 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1537 g1_rs.size()/HeapWordSize);
1538 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1540 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1542 _g1_storage.initialize(g1_rs, 0);
1543 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1544 _g1_max_committed = _g1_committed;
1545 _hrs = new HeapRegionSeq(_expansion_regions);
1546 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1547 guarantee(_cur_alloc_region == NULL, "from constructor");
1549 // 6843694 - ensure that the maximum region index can fit
1550 // in the remembered set structures.
1551 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1552 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1554 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1555 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1556 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1557 "too many cards per region");
1559 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1560 heap_word_size(init_byte_size));
1562 _g1h = this;
1564 // Create the ConcurrentMark data structure and thread.
1565 // (Must do this late, so that "max_regions" is defined.)
1566 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1567 _cmThread = _cm->cmThread();
1569 // ...and the concurrent zero-fill thread, if necessary.
1570 if (G1ConcZeroFill) {
1571 _czft = new ConcurrentZFThread();
1572 }
1574 // Initialize the from_card cache structure of HeapRegionRemSet.
1575 HeapRegionRemSet::init_heap(max_regions());
1577 // Now expand into the initial heap size.
1578 expand(init_byte_size);
1580 // Perform any initialization actions delegated to the policy.
1581 g1_policy()->init();
1583 g1_policy()->note_start_of_mark_thread();
1585 _refine_cte_cl =
1586 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1587 g1_rem_set(),
1588 concurrent_g1_refine());
1589 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1591 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1592 SATB_Q_FL_lock,
1593 0,
1594 Shared_SATB_Q_lock);
1596 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1597 DirtyCardQ_FL_lock,
1598 G1UpdateBufferQueueMaxLength,
1599 Shared_DirtyCardQ_lock);
1601 if (G1DeferredRSUpdate) {
1602 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1603 DirtyCardQ_FL_lock,
1604 0,
1605 Shared_DirtyCardQ_lock,
1606 &JavaThread::dirty_card_queue_set());
1607 }
1608 // In case we're keeping closure specialization stats, initialize those
1609 // counts and that mechanism.
1610 SpecializationStats::clear();
1612 _gc_alloc_region_list = NULL;
1614 // Do later initialization work for concurrent refinement.
1615 _cg1r->init();
1617 return JNI_OK;
1618 }
1620 void G1CollectedHeap::ref_processing_init() {
1621 SharedHeap::ref_processing_init();
1622 MemRegion mr = reserved_region();
1623 _ref_processor = ReferenceProcessor::create_ref_processor(
1624 mr, // span
1625 false, // Reference discovery is not atomic
1626 // (though it shouldn't matter here.)
1627 true, // mt_discovery
1628 NULL, // is alive closure: need to fill this in for efficiency
1629 ParallelGCThreads,
1630 ParallelRefProcEnabled,
1631 true); // Setting next fields of discovered
1632 // lists requires a barrier.
1633 }
1635 size_t G1CollectedHeap::capacity() const {
1636 return _g1_committed.byte_size();
1637 }
1639 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1640 int worker_i) {
1641 // Clean cards in the hot card cache
1642 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set());
1644 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1645 int n_completed_buffers = 0;
1646 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1647 n_completed_buffers++;
1648 }
1649 g1_policy()->record_update_rs_processed_buffers(worker_i,
1650 (double) n_completed_buffers);
1651 dcqs.clear_n_completed_buffers();
1652 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1653 }
1656 // Computes the sum of the storage used by the various regions.
1658 size_t G1CollectedHeap::used() const {
1659 assert(Heap_lock->owner() != NULL,
1660 "Should be owned on this thread's behalf.");
1661 size_t result = _summary_bytes_used;
1662 // Read only once in case it is set to NULL concurrently
1663 HeapRegion* hr = _cur_alloc_region;
1664 if (hr != NULL)
1665 result += hr->used();
1666 return result;
1667 }
1669 size_t G1CollectedHeap::used_unlocked() const {
1670 size_t result = _summary_bytes_used;
1671 return result;
1672 }
1674 class SumUsedClosure: public HeapRegionClosure {
1675 size_t _used;
1676 public:
1677 SumUsedClosure() : _used(0) {}
1678 bool doHeapRegion(HeapRegion* r) {
1679 if (!r->continuesHumongous()) {
1680 _used += r->used();
1681 }
1682 return false;
1683 }
1684 size_t result() { return _used; }
1685 };
1687 size_t G1CollectedHeap::recalculate_used() const {
1688 SumUsedClosure blk;
1689 _hrs->iterate(&blk);
1690 return blk.result();
1691 }
1693 #ifndef PRODUCT
1694 class SumUsedRegionsClosure: public HeapRegionClosure {
1695 size_t _num;
1696 public:
1697 SumUsedRegionsClosure() : _num(0) {}
1698 bool doHeapRegion(HeapRegion* r) {
1699 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1700 _num += 1;
1701 }
1702 return false;
1703 }
1704 size_t result() { return _num; }
1705 };
1707 size_t G1CollectedHeap::recalculate_used_regions() const {
1708 SumUsedRegionsClosure blk;
1709 _hrs->iterate(&blk);
1710 return blk.result();
1711 }
1712 #endif // PRODUCT
1714 size_t G1CollectedHeap::unsafe_max_alloc() {
1715 if (_free_regions > 0) return HeapRegion::GrainBytes;
1716 // otherwise, is there space in the current allocation region?
1718 // We need to store the current allocation region in a local variable
1719 // here. The problem is that this method doesn't take any locks and
1720 // there may be other threads which overwrite the current allocation
1721 // region field. attempt_allocation(), for example, sets it to NULL
1722 // and this can happen *after* the NULL check here but before the call
1723 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1724 // to be a problem in the optimized build, since the two loads of the
1725 // current allocation region field are optimized away.
1726 HeapRegion* car = _cur_alloc_region;
1728 // FIXME: should iterate over all regions?
1729 if (car == NULL) {
1730 return 0;
1731 }
1732 return car->free();
1733 }
1735 void G1CollectedHeap::collect(GCCause::Cause cause) {
1736 // The caller doesn't have the Heap_lock
1737 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1738 MutexLocker ml(Heap_lock);
1739 collect_locked(cause);
1740 }
1742 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1743 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1744 assert(Heap_lock->is_locked(), "Precondition#2");
1745 GCCauseSetter gcs(this, cause);
1746 switch (cause) {
1747 case GCCause::_heap_inspection:
1748 case GCCause::_heap_dump: {
1749 HandleMark hm;
1750 do_full_collection(false); // don't clear all soft refs
1751 break;
1752 }
1753 default: // XXX FIX ME
1754 ShouldNotReachHere(); // Unexpected use of this function
1755 }
1756 }
1759 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1760 // Don't want to do a GC until cleanup is completed.
1761 wait_for_cleanup_complete();
1763 // Read the GC count while holding the Heap_lock
1764 int gc_count_before = SharedHeap::heap()->total_collections();
1765 {
1766 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1767 VM_G1CollectFull op(gc_count_before, cause);
1768 VMThread::execute(&op);
1769 }
1770 }
1772 bool G1CollectedHeap::is_in(const void* p) const {
1773 if (_g1_committed.contains(p)) {
1774 HeapRegion* hr = _hrs->addr_to_region(p);
1775 return hr->is_in(p);
1776 } else {
1777 return _perm_gen->as_gen()->is_in(p);
1778 }
1779 }
1781 // Iteration functions.
1783 // Iterates an OopClosure over all ref-containing fields of objects
1784 // within a HeapRegion.
1786 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1787 MemRegion _mr;
1788 OopClosure* _cl;
1789 public:
1790 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1791 : _mr(mr), _cl(cl) {}
1792 bool doHeapRegion(HeapRegion* r) {
1793 if (! r->continuesHumongous()) {
1794 r->oop_iterate(_cl);
1795 }
1796 return false;
1797 }
1798 };
1800 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1801 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1802 _hrs->iterate(&blk);
1803 if (do_perm) {
1804 perm_gen()->oop_iterate(cl);
1805 }
1806 }
1808 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1809 IterateOopClosureRegionClosure blk(mr, cl);
1810 _hrs->iterate(&blk);
1811 if (do_perm) {
1812 perm_gen()->oop_iterate(cl);
1813 }
1814 }
1816 // Iterates an ObjectClosure over all objects within a HeapRegion.
1818 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1819 ObjectClosure* _cl;
1820 public:
1821 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1822 bool doHeapRegion(HeapRegion* r) {
1823 if (! r->continuesHumongous()) {
1824 r->object_iterate(_cl);
1825 }
1826 return false;
1827 }
1828 };
1830 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1831 IterateObjectClosureRegionClosure blk(cl);
1832 _hrs->iterate(&blk);
1833 if (do_perm) {
1834 perm_gen()->object_iterate(cl);
1835 }
1836 }
1838 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1839 // FIXME: is this right?
1840 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1841 }
1843 // Calls a SpaceClosure on a HeapRegion.
1845 class SpaceClosureRegionClosure: public HeapRegionClosure {
1846 SpaceClosure* _cl;
1847 public:
1848 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1849 bool doHeapRegion(HeapRegion* r) {
1850 _cl->do_space(r);
1851 return false;
1852 }
1853 };
1855 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1856 SpaceClosureRegionClosure blk(cl);
1857 _hrs->iterate(&blk);
1858 }
1860 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1861 _hrs->iterate(cl);
1862 }
1864 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1865 HeapRegionClosure* cl) {
1866 _hrs->iterate_from(r, cl);
1867 }
1869 void
1870 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1871 _hrs->iterate_from(idx, cl);
1872 }
1874 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1876 void
1877 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1878 int worker,
1879 jint claim_value) {
1880 const size_t regions = n_regions();
1881 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1882 // try to spread out the starting points of the workers
1883 const size_t start_index = regions / worker_num * (size_t) worker;
1885 // each worker will actually look at all regions
1886 for (size_t count = 0; count < regions; ++count) {
1887 const size_t index = (start_index + count) % regions;
1888 assert(0 <= index && index < regions, "sanity");
1889 HeapRegion* r = region_at(index);
1890 // we'll ignore "continues humongous" regions (we'll process them
1891 // when we come across their corresponding "start humongous"
1892 // region) and regions already claimed
1893 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1894 continue;
1895 }
1896 // OK, try to claim it
1897 if (r->claimHeapRegion(claim_value)) {
1898 // success!
1899 assert(!r->continuesHumongous(), "sanity");
1900 if (r->startsHumongous()) {
1901 // If the region is "starts humongous" we'll iterate over its
1902 // "continues humongous" first; in fact we'll do them
1903 // first. The order is important. In on case, calling the
1904 // closure on the "starts humongous" region might de-allocate
1905 // and clear all its "continues humongous" regions and, as a
1906 // result, we might end up processing them twice. So, we'll do
1907 // them first (notice: most closures will ignore them anyway) and
1908 // then we'll do the "starts humongous" region.
1909 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1910 HeapRegion* chr = region_at(ch_index);
1912 // if the region has already been claimed or it's not
1913 // "continues humongous" we're done
1914 if (chr->claim_value() == claim_value ||
1915 !chr->continuesHumongous()) {
1916 break;
1917 }
1919 // Noone should have claimed it directly. We can given
1920 // that we claimed its "starts humongous" region.
1921 assert(chr->claim_value() != claim_value, "sanity");
1922 assert(chr->humongous_start_region() == r, "sanity");
1924 if (chr->claimHeapRegion(claim_value)) {
1925 // we should always be able to claim it; noone else should
1926 // be trying to claim this region
1928 bool res2 = cl->doHeapRegion(chr);
1929 assert(!res2, "Should not abort");
1931 // Right now, this holds (i.e., no closure that actually
1932 // does something with "continues humongous" regions
1933 // clears them). We might have to weaken it in the future,
1934 // but let's leave these two asserts here for extra safety.
1935 assert(chr->continuesHumongous(), "should still be the case");
1936 assert(chr->humongous_start_region() == r, "sanity");
1937 } else {
1938 guarantee(false, "we should not reach here");
1939 }
1940 }
1941 }
1943 assert(!r->continuesHumongous(), "sanity");
1944 bool res = cl->doHeapRegion(r);
1945 assert(!res, "Should not abort");
1946 }
1947 }
1948 }
1950 class ResetClaimValuesClosure: public HeapRegionClosure {
1951 public:
1952 bool doHeapRegion(HeapRegion* r) {
1953 r->set_claim_value(HeapRegion::InitialClaimValue);
1954 return false;
1955 }
1956 };
1958 void
1959 G1CollectedHeap::reset_heap_region_claim_values() {
1960 ResetClaimValuesClosure blk;
1961 heap_region_iterate(&blk);
1962 }
1964 #ifdef ASSERT
1965 // This checks whether all regions in the heap have the correct claim
1966 // value. I also piggy-backed on this a check to ensure that the
1967 // humongous_start_region() information on "continues humongous"
1968 // regions is correct.
1970 class CheckClaimValuesClosure : public HeapRegionClosure {
1971 private:
1972 jint _claim_value;
1973 size_t _failures;
1974 HeapRegion* _sh_region;
1975 public:
1976 CheckClaimValuesClosure(jint claim_value) :
1977 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1978 bool doHeapRegion(HeapRegion* r) {
1979 if (r->claim_value() != _claim_value) {
1980 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1981 "claim value = %d, should be %d",
1982 r->bottom(), r->end(), r->claim_value(),
1983 _claim_value);
1984 ++_failures;
1985 }
1986 if (!r->isHumongous()) {
1987 _sh_region = NULL;
1988 } else if (r->startsHumongous()) {
1989 _sh_region = r;
1990 } else if (r->continuesHumongous()) {
1991 if (r->humongous_start_region() != _sh_region) {
1992 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1993 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1994 r->bottom(), r->end(),
1995 r->humongous_start_region(),
1996 _sh_region);
1997 ++_failures;
1998 }
1999 }
2000 return false;
2001 }
2002 size_t failures() {
2003 return _failures;
2004 }
2005 };
2007 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2008 CheckClaimValuesClosure cl(claim_value);
2009 heap_region_iterate(&cl);
2010 return cl.failures() == 0;
2011 }
2012 #endif // ASSERT
2014 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2015 HeapRegion* r = g1_policy()->collection_set();
2016 while (r != NULL) {
2017 HeapRegion* next = r->next_in_collection_set();
2018 if (cl->doHeapRegion(r)) {
2019 cl->incomplete();
2020 return;
2021 }
2022 r = next;
2023 }
2024 }
2026 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2027 HeapRegionClosure *cl) {
2028 assert(r->in_collection_set(),
2029 "Start region must be a member of the collection set.");
2030 HeapRegion* cur = r;
2031 while (cur != NULL) {
2032 HeapRegion* next = cur->next_in_collection_set();
2033 if (cl->doHeapRegion(cur) && false) {
2034 cl->incomplete();
2035 return;
2036 }
2037 cur = next;
2038 }
2039 cur = g1_policy()->collection_set();
2040 while (cur != r) {
2041 HeapRegion* next = cur->next_in_collection_set();
2042 if (cl->doHeapRegion(cur) && false) {
2043 cl->incomplete();
2044 return;
2045 }
2046 cur = next;
2047 }
2048 }
2050 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2051 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2052 }
2055 Space* G1CollectedHeap::space_containing(const void* addr) const {
2056 Space* res = heap_region_containing(addr);
2057 if (res == NULL)
2058 res = perm_gen()->space_containing(addr);
2059 return res;
2060 }
2062 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2063 Space* sp = space_containing(addr);
2064 if (sp != NULL) {
2065 return sp->block_start(addr);
2066 }
2067 return NULL;
2068 }
2070 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2071 Space* sp = space_containing(addr);
2072 assert(sp != NULL, "block_size of address outside of heap");
2073 return sp->block_size(addr);
2074 }
2076 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2077 Space* sp = space_containing(addr);
2078 return sp->block_is_obj(addr);
2079 }
2081 bool G1CollectedHeap::supports_tlab_allocation() const {
2082 return true;
2083 }
2085 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2086 return HeapRegion::GrainBytes;
2087 }
2089 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2090 // Return the remaining space in the cur alloc region, but not less than
2091 // the min TLAB size.
2092 // Also, no more than half the region size, since we can't allow tlabs to
2093 // grow big enough to accomodate humongous objects.
2095 // We need to story it locally, since it might change between when we
2096 // test for NULL and when we use it later.
2097 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2098 if (cur_alloc_space == NULL) {
2099 return HeapRegion::GrainBytes/2;
2100 } else {
2101 return MAX2(MIN2(cur_alloc_space->free(),
2102 (size_t)(HeapRegion::GrainBytes/2)),
2103 (size_t)MinTLABSize);
2104 }
2105 }
2107 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2108 bool dummy;
2109 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2110 }
2112 bool G1CollectedHeap::allocs_are_zero_filled() {
2113 return false;
2114 }
2116 size_t G1CollectedHeap::large_typearray_limit() {
2117 // FIXME
2118 return HeapRegion::GrainBytes/HeapWordSize;
2119 }
2121 size_t G1CollectedHeap::max_capacity() const {
2122 return _g1_committed.byte_size();
2123 }
2125 jlong G1CollectedHeap::millis_since_last_gc() {
2126 // assert(false, "NYI");
2127 return 0;
2128 }
2131 void G1CollectedHeap::prepare_for_verify() {
2132 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2133 ensure_parsability(false);
2134 }
2135 g1_rem_set()->prepare_for_verify();
2136 }
2138 class VerifyLivenessOopClosure: public OopClosure {
2139 G1CollectedHeap* g1h;
2140 public:
2141 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2142 g1h = _g1h;
2143 }
2144 void do_oop(narrowOop *p) { do_oop_work(p); }
2145 void do_oop( oop *p) { do_oop_work(p); }
2147 template <class T> void do_oop_work(T *p) {
2148 oop obj = oopDesc::load_decode_heap_oop(p);
2149 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2150 "Dead object referenced by a not dead object");
2151 }
2152 };
2154 class VerifyObjsInRegionClosure: public ObjectClosure {
2155 private:
2156 G1CollectedHeap* _g1h;
2157 size_t _live_bytes;
2158 HeapRegion *_hr;
2159 bool _use_prev_marking;
2160 public:
2161 // use_prev_marking == true -> use "prev" marking information,
2162 // use_prev_marking == false -> use "next" marking information
2163 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2164 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2165 _g1h = G1CollectedHeap::heap();
2166 }
2167 void do_object(oop o) {
2168 VerifyLivenessOopClosure isLive(_g1h);
2169 assert(o != NULL, "Huh?");
2170 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2171 o->oop_iterate(&isLive);
2172 if (!_hr->obj_allocated_since_prev_marking(o))
2173 _live_bytes += (o->size() * HeapWordSize);
2174 }
2175 }
2176 size_t live_bytes() { return _live_bytes; }
2177 };
2179 class PrintObjsInRegionClosure : public ObjectClosure {
2180 HeapRegion *_hr;
2181 G1CollectedHeap *_g1;
2182 public:
2183 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2184 _g1 = G1CollectedHeap::heap();
2185 };
2187 void do_object(oop o) {
2188 if (o != NULL) {
2189 HeapWord *start = (HeapWord *) o;
2190 size_t word_sz = o->size();
2191 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2192 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2193 (void*) o, word_sz,
2194 _g1->isMarkedPrev(o),
2195 _g1->isMarkedNext(o),
2196 _hr->obj_allocated_since_prev_marking(o));
2197 HeapWord *end = start + word_sz;
2198 HeapWord *cur;
2199 int *val;
2200 for (cur = start; cur < end; cur++) {
2201 val = (int *) cur;
2202 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2203 }
2204 }
2205 }
2206 };
2208 class VerifyRegionClosure: public HeapRegionClosure {
2209 private:
2210 bool _allow_dirty;
2211 bool _par;
2212 bool _use_prev_marking;
2213 bool _failures;
2214 public:
2215 // use_prev_marking == true -> use "prev" marking information,
2216 // use_prev_marking == false -> use "next" marking information
2217 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2218 : _allow_dirty(allow_dirty),
2219 _par(par),
2220 _use_prev_marking(use_prev_marking),
2221 _failures(false) {}
2223 bool failures() {
2224 return _failures;
2225 }
2227 bool doHeapRegion(HeapRegion* r) {
2228 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2229 "Should be unclaimed at verify points.");
2230 if (!r->continuesHumongous()) {
2231 bool failures = false;
2232 r->verify(_allow_dirty, _use_prev_marking, &failures);
2233 if (failures) {
2234 _failures = true;
2235 } else {
2236 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2237 r->object_iterate(¬_dead_yet_cl);
2238 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2239 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2240 "max_live_bytes "SIZE_FORMAT" "
2241 "< calculated "SIZE_FORMAT,
2242 r->bottom(), r->end(),
2243 r->max_live_bytes(),
2244 not_dead_yet_cl.live_bytes());
2245 _failures = true;
2246 }
2247 }
2248 }
2249 return false; // stop the region iteration if we hit a failure
2250 }
2251 };
2253 class VerifyRootsClosure: public OopsInGenClosure {
2254 private:
2255 G1CollectedHeap* _g1h;
2256 bool _use_prev_marking;
2257 bool _failures;
2258 public:
2259 // use_prev_marking == true -> use "prev" marking information,
2260 // use_prev_marking == false -> use "next" marking information
2261 VerifyRootsClosure(bool use_prev_marking) :
2262 _g1h(G1CollectedHeap::heap()),
2263 _use_prev_marking(use_prev_marking),
2264 _failures(false) { }
2266 bool failures() { return _failures; }
2268 template <class T> void do_oop_nv(T* p) {
2269 T heap_oop = oopDesc::load_heap_oop(p);
2270 if (!oopDesc::is_null(heap_oop)) {
2271 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2272 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2273 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2274 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2275 obj->print_on(gclog_or_tty);
2276 _failures = true;
2277 }
2278 }
2279 }
2281 void do_oop(oop* p) { do_oop_nv(p); }
2282 void do_oop(narrowOop* p) { do_oop_nv(p); }
2283 };
2285 // This is the task used for parallel heap verification.
2287 class G1ParVerifyTask: public AbstractGangTask {
2288 private:
2289 G1CollectedHeap* _g1h;
2290 bool _allow_dirty;
2291 bool _use_prev_marking;
2292 bool _failures;
2294 public:
2295 // use_prev_marking == true -> use "prev" marking information,
2296 // use_prev_marking == false -> use "next" marking information
2297 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2298 bool use_prev_marking) :
2299 AbstractGangTask("Parallel verify task"),
2300 _g1h(g1h),
2301 _allow_dirty(allow_dirty),
2302 _use_prev_marking(use_prev_marking),
2303 _failures(false) { }
2305 bool failures() {
2306 return _failures;
2307 }
2309 void work(int worker_i) {
2310 HandleMark hm;
2311 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2312 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2313 HeapRegion::ParVerifyClaimValue);
2314 if (blk.failures()) {
2315 _failures = true;
2316 }
2317 }
2318 };
2320 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2321 verify(allow_dirty, silent, /* use_prev_marking */ true);
2322 }
2324 void G1CollectedHeap::verify(bool allow_dirty,
2325 bool silent,
2326 bool use_prev_marking) {
2327 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2328 if (!silent) { gclog_or_tty->print("roots "); }
2329 VerifyRootsClosure rootsCl(use_prev_marking);
2330 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2331 process_strong_roots(true, // activate StrongRootsScope
2332 false,
2333 SharedHeap::SO_AllClasses,
2334 &rootsCl,
2335 &blobsCl,
2336 &rootsCl);
2337 bool failures = rootsCl.failures();
2338 rem_set()->invalidate(perm_gen()->used_region(), false);
2339 if (!silent) { gclog_or_tty->print("heapRegions "); }
2340 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2341 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2342 "sanity check");
2344 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2345 int n_workers = workers()->total_workers();
2346 set_par_threads(n_workers);
2347 workers()->run_task(&task);
2348 set_par_threads(0);
2349 if (task.failures()) {
2350 failures = true;
2351 }
2353 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2354 "sanity check");
2356 reset_heap_region_claim_values();
2358 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2359 "sanity check");
2360 } else {
2361 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2362 _hrs->iterate(&blk);
2363 if (blk.failures()) {
2364 failures = true;
2365 }
2366 }
2367 if (!silent) gclog_or_tty->print("remset ");
2368 rem_set()->verify();
2370 if (failures) {
2371 gclog_or_tty->print_cr("Heap:");
2372 print_on(gclog_or_tty, true /* extended */);
2373 gclog_or_tty->print_cr("");
2374 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2375 concurrent_mark()->print_reachable(use_prev_marking,
2376 "failed-verification");
2377 }
2378 gclog_or_tty->flush();
2379 }
2380 guarantee(!failures, "there should not have been any failures");
2381 } else {
2382 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2383 }
2384 }
2386 class PrintRegionClosure: public HeapRegionClosure {
2387 outputStream* _st;
2388 public:
2389 PrintRegionClosure(outputStream* st) : _st(st) {}
2390 bool doHeapRegion(HeapRegion* r) {
2391 r->print_on(_st);
2392 return false;
2393 }
2394 };
2396 void G1CollectedHeap::print() const { print_on(tty); }
2398 void G1CollectedHeap::print_on(outputStream* st) const {
2399 print_on(st, PrintHeapAtGCExtended);
2400 }
2402 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2403 st->print(" %-20s", "garbage-first heap");
2404 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2405 capacity()/K, used_unlocked()/K);
2406 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2407 _g1_storage.low_boundary(),
2408 _g1_storage.high(),
2409 _g1_storage.high_boundary());
2410 st->cr();
2411 st->print(" region size " SIZE_FORMAT "K, ",
2412 HeapRegion::GrainBytes/K);
2413 size_t young_regions = _young_list->length();
2414 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2415 young_regions, young_regions * HeapRegion::GrainBytes / K);
2416 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2417 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2418 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2419 st->cr();
2420 perm()->as_gen()->print_on(st);
2421 if (extended) {
2422 st->cr();
2423 print_on_extended(st);
2424 }
2425 }
2427 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2428 PrintRegionClosure blk(st);
2429 _hrs->iterate(&blk);
2430 }
2432 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2433 if (ParallelGCThreads > 0) {
2434 workers()->print_worker_threads_on(st);
2435 }
2437 _cmThread->print_on(st);
2438 st->cr();
2440 _cm->print_worker_threads_on(st);
2442 _cg1r->print_worker_threads_on(st);
2444 _czft->print_on(st);
2445 st->cr();
2446 }
2448 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2449 if (ParallelGCThreads > 0) {
2450 workers()->threads_do(tc);
2451 }
2452 tc->do_thread(_cmThread);
2453 _cg1r->threads_do(tc);
2454 tc->do_thread(_czft);
2455 }
2457 void G1CollectedHeap::print_tracing_info() const {
2458 // We'll overload this to mean "trace GC pause statistics."
2459 if (TraceGen0Time || TraceGen1Time) {
2460 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2461 // to that.
2462 g1_policy()->print_tracing_info();
2463 }
2464 if (G1SummarizeRSetStats) {
2465 g1_rem_set()->print_summary_info();
2466 }
2467 if (G1SummarizeConcurrentMark) {
2468 concurrent_mark()->print_summary_info();
2469 }
2470 if (G1SummarizeZFStats) {
2471 ConcurrentZFThread::print_summary_info();
2472 }
2473 g1_policy()->print_yg_surv_rate_info();
2475 SpecializationStats::print();
2476 }
2479 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2480 HeapRegion* hr = heap_region_containing(addr);
2481 if (hr == NULL) {
2482 return 0;
2483 } else {
2484 return 1;
2485 }
2486 }
2488 G1CollectedHeap* G1CollectedHeap::heap() {
2489 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2490 "not a garbage-first heap");
2491 return _g1h;
2492 }
2494 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2495 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2496 // Call allocation profiler
2497 AllocationProfiler::iterate_since_last_gc();
2498 // Fill TLAB's and such
2499 ensure_parsability(true);
2500 }
2502 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2503 // FIXME: what is this about?
2504 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2505 // is set.
2506 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2507 "derived pointer present"));
2508 }
2510 void G1CollectedHeap::do_collection_pause() {
2511 // Read the GC count while holding the Heap_lock
2512 // we need to do this _before_ wait_for_cleanup_complete(), to
2513 // ensure that we do not give up the heap lock and potentially
2514 // pick up the wrong count
2515 int gc_count_before = SharedHeap::heap()->total_collections();
2517 // Don't want to do a GC pause while cleanup is being completed!
2518 wait_for_cleanup_complete();
2520 g1_policy()->record_stop_world_start();
2521 {
2522 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2523 VM_G1IncCollectionPause op(gc_count_before);
2524 VMThread::execute(&op);
2525 }
2526 }
2528 void
2529 G1CollectedHeap::doConcurrentMark() {
2530 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2531 if (!_cmThread->in_progress()) {
2532 _cmThread->set_started();
2533 CGC_lock->notify();
2534 }
2535 }
2537 class VerifyMarkedObjsClosure: public ObjectClosure {
2538 G1CollectedHeap* _g1h;
2539 public:
2540 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2541 void do_object(oop obj) {
2542 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2543 "markandsweep mark should agree with concurrent deadness");
2544 }
2545 };
2547 void
2548 G1CollectedHeap::checkConcurrentMark() {
2549 VerifyMarkedObjsClosure verifycl(this);
2550 // MutexLockerEx x(getMarkBitMapLock(),
2551 // Mutex::_no_safepoint_check_flag);
2552 object_iterate(&verifycl, false);
2553 }
2555 void G1CollectedHeap::do_sync_mark() {
2556 _cm->checkpointRootsInitial();
2557 _cm->markFromRoots();
2558 _cm->checkpointRootsFinal(false);
2559 }
2561 // <NEW PREDICTION>
2563 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2564 bool young) {
2565 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2566 }
2568 void G1CollectedHeap::check_if_region_is_too_expensive(double
2569 predicted_time_ms) {
2570 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2571 }
2573 size_t G1CollectedHeap::pending_card_num() {
2574 size_t extra_cards = 0;
2575 JavaThread *curr = Threads::first();
2576 while (curr != NULL) {
2577 DirtyCardQueue& dcq = curr->dirty_card_queue();
2578 extra_cards += dcq.size();
2579 curr = curr->next();
2580 }
2581 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2582 size_t buffer_size = dcqs.buffer_size();
2583 size_t buffer_num = dcqs.completed_buffers_num();
2584 return buffer_size * buffer_num + extra_cards;
2585 }
2587 size_t G1CollectedHeap::max_pending_card_num() {
2588 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2589 size_t buffer_size = dcqs.buffer_size();
2590 size_t buffer_num = dcqs.completed_buffers_num();
2591 int thread_num = Threads::number_of_threads();
2592 return (buffer_num + thread_num) * buffer_size;
2593 }
2595 size_t G1CollectedHeap::cards_scanned() {
2596 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2597 return g1_rset->cardsScanned();
2598 }
2600 void
2601 G1CollectedHeap::setup_surviving_young_words() {
2602 guarantee( _surviving_young_words == NULL, "pre-condition" );
2603 size_t array_length = g1_policy()->young_cset_length();
2604 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2605 if (_surviving_young_words == NULL) {
2606 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2607 "Not enough space for young surv words summary.");
2608 }
2609 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2610 #ifdef ASSERT
2611 for (size_t i = 0; i < array_length; ++i) {
2612 assert( _surviving_young_words[i] == 0, "memset above" );
2613 }
2614 #endif // !ASSERT
2615 }
2617 void
2618 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2619 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2620 size_t array_length = g1_policy()->young_cset_length();
2621 for (size_t i = 0; i < array_length; ++i)
2622 _surviving_young_words[i] += surv_young_words[i];
2623 }
2625 void
2626 G1CollectedHeap::cleanup_surviving_young_words() {
2627 guarantee( _surviving_young_words != NULL, "pre-condition" );
2628 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2629 _surviving_young_words = NULL;
2630 }
2632 // </NEW PREDICTION>
2634 void
2635 G1CollectedHeap::do_collection_pause_at_safepoint() {
2636 if (PrintHeapAtGC) {
2637 Universe::print_heap_before_gc();
2638 }
2640 {
2641 char verbose_str[128];
2642 sprintf(verbose_str, "GC pause ");
2643 if (g1_policy()->in_young_gc_mode()) {
2644 if (g1_policy()->full_young_gcs())
2645 strcat(verbose_str, "(young)");
2646 else
2647 strcat(verbose_str, "(partial)");
2648 }
2649 if (g1_policy()->should_initiate_conc_mark())
2650 strcat(verbose_str, " (initial-mark)");
2652 GCCauseSetter x(this, GCCause::_g1_inc_collection_pause);
2654 // if PrintGCDetails is on, we'll print long statistics information
2655 // in the collector policy code, so let's not print this as the output
2656 // is messy if we do.
2657 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2658 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2659 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2661 ResourceMark rm;
2662 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2663 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2664 guarantee(!is_gc_active(), "collection is not reentrant");
2665 assert(regions_accounted_for(), "Region leakage!");
2667 increment_gc_time_stamp();
2669 if (g1_policy()->in_young_gc_mode()) {
2670 assert(check_young_list_well_formed(),
2671 "young list should be well formed");
2672 }
2674 if (GC_locker::is_active()) {
2675 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2676 }
2678 bool abandoned = false;
2679 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2680 IsGCActiveMark x;
2682 gc_prologue(false);
2683 increment_total_collections(false /* full gc */);
2685 #if G1_REM_SET_LOGGING
2686 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2687 print();
2688 #endif
2690 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2691 HandleMark hm; // Discard invalid handles created during verification
2692 prepare_for_verify();
2693 gclog_or_tty->print(" VerifyBeforeGC:");
2694 Universe::verify(false);
2695 }
2697 COMPILER2_PRESENT(DerivedPointerTable::clear());
2699 // We want to turn off ref discovery, if necessary, and turn it back on
2700 // on again later if we do. XXX Dubious: why is discovery disabled?
2701 bool was_enabled = ref_processor()->discovery_enabled();
2702 if (was_enabled) ref_processor()->disable_discovery();
2704 // Forget the current alloc region (we might even choose it to be part
2705 // of the collection set!).
2706 abandon_cur_alloc_region();
2708 // The elapsed time induced by the start time below deliberately elides
2709 // the possible verification above.
2710 double start_time_sec = os::elapsedTime();
2711 size_t start_used_bytes = used();
2713 g1_policy()->record_collection_pause_start(start_time_sec,
2714 start_used_bytes);
2716 guarantee(_in_cset_fast_test == NULL, "invariant");
2717 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2718 _in_cset_fast_test_length = max_regions();
2719 _in_cset_fast_test_base =
2720 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2721 memset(_in_cset_fast_test_base, false,
2722 _in_cset_fast_test_length * sizeof(bool));
2723 // We're biasing _in_cset_fast_test to avoid subtracting the
2724 // beginning of the heap every time we want to index; basically
2725 // it's the same with what we do with the card table.
2726 _in_cset_fast_test = _in_cset_fast_test_base -
2727 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2729 #if SCAN_ONLY_VERBOSE
2730 _young_list->print();
2731 #endif // SCAN_ONLY_VERBOSE
2733 if (g1_policy()->should_initiate_conc_mark()) {
2734 concurrent_mark()->checkpointRootsInitialPre();
2735 }
2736 save_marks();
2738 // We must do this before any possible evacuation that should propagate
2739 // marks.
2740 if (mark_in_progress()) {
2741 double start_time_sec = os::elapsedTime();
2743 _cm->drainAllSATBBuffers();
2744 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2745 g1_policy()->record_satb_drain_time(finish_mark_ms);
2746 }
2747 // Record the number of elements currently on the mark stack, so we
2748 // only iterate over these. (Since evacuation may add to the mark
2749 // stack, doing more exposes race conditions.) If no mark is in
2750 // progress, this will be zero.
2751 _cm->set_oops_do_bound();
2753 assert(regions_accounted_for(), "Region leakage.");
2755 if (mark_in_progress())
2756 concurrent_mark()->newCSet();
2758 // Now choose the CS.
2759 g1_policy()->choose_collection_set();
2761 // We may abandon a pause if we find no region that will fit in the MMU
2762 // pause.
2763 bool abandoned = (g1_policy()->collection_set() == NULL);
2765 // Nothing to do if we were unable to choose a collection set.
2766 if (!abandoned) {
2767 #if G1_REM_SET_LOGGING
2768 gclog_or_tty->print_cr("\nAfter pause, heap:");
2769 print();
2770 #endif
2772 setup_surviving_young_words();
2774 // Set up the gc allocation regions.
2775 get_gc_alloc_regions();
2777 // Actually do the work...
2778 evacuate_collection_set();
2779 free_collection_set(g1_policy()->collection_set());
2780 g1_policy()->clear_collection_set();
2782 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2783 // this is more for peace of mind; we're nulling them here and
2784 // we're expecting them to be null at the beginning of the next GC
2785 _in_cset_fast_test = NULL;
2786 _in_cset_fast_test_base = NULL;
2788 cleanup_surviving_young_words();
2790 if (g1_policy()->in_young_gc_mode()) {
2791 _young_list->reset_sampled_info();
2792 assert(check_young_list_empty(true),
2793 "young list should be empty");
2795 #if SCAN_ONLY_VERBOSE
2796 _young_list->print();
2797 #endif // SCAN_ONLY_VERBOSE
2799 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2800 _young_list->first_survivor_region(),
2801 _young_list->last_survivor_region());
2802 _young_list->reset_auxilary_lists();
2803 }
2804 } else {
2805 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2806 }
2808 if (evacuation_failed()) {
2809 _summary_bytes_used = recalculate_used();
2810 } else {
2811 // The "used" of the the collection set have already been subtracted
2812 // when they were freed. Add in the bytes evacuated.
2813 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2814 }
2816 if (g1_policy()->in_young_gc_mode() &&
2817 g1_policy()->should_initiate_conc_mark()) {
2818 concurrent_mark()->checkpointRootsInitialPost();
2819 set_marking_started();
2820 // CAUTION: after the doConcurrentMark() call below,
2821 // the concurrent marking thread(s) could be running
2822 // concurrently with us. Make sure that anything after
2823 // this point does not assume that we are the only GC thread
2824 // running. Note: of course, the actual marking work will
2825 // not start until the safepoint itself is released in
2826 // ConcurrentGCThread::safepoint_desynchronize().
2827 doConcurrentMark();
2828 }
2830 #if SCAN_ONLY_VERBOSE
2831 _young_list->print();
2832 #endif // SCAN_ONLY_VERBOSE
2834 double end_time_sec = os::elapsedTime();
2835 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2836 g1_policy()->record_pause_time_ms(pause_time_ms);
2837 g1_policy()->record_collection_pause_end(abandoned);
2839 assert(regions_accounted_for(), "Region leakage.");
2841 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2842 HandleMark hm; // Discard invalid handles created during verification
2843 gclog_or_tty->print(" VerifyAfterGC:");
2844 prepare_for_verify();
2845 Universe::verify(false);
2846 }
2848 if (was_enabled) ref_processor()->enable_discovery();
2850 {
2851 size_t expand_bytes = g1_policy()->expansion_amount();
2852 if (expand_bytes > 0) {
2853 size_t bytes_before = capacity();
2854 expand(expand_bytes);
2855 }
2856 }
2858 if (mark_in_progress()) {
2859 concurrent_mark()->update_g1_committed();
2860 }
2862 #ifdef TRACESPINNING
2863 ParallelTaskTerminator::print_termination_counts();
2864 #endif
2866 gc_epilogue(false);
2867 }
2869 assert(verify_region_lists(), "Bad region lists.");
2871 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2872 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2873 print_tracing_info();
2874 vm_exit(-1);
2875 }
2876 }
2878 if (PrintHeapAtGC) {
2879 Universe::print_heap_after_gc();
2880 }
2881 if (G1SummarizeRSetStats &&
2882 (G1SummarizeRSetStatsPeriod > 0) &&
2883 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
2884 g1_rem_set()->print_summary_info();
2885 }
2886 }
2888 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2889 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2890 // make sure we don't call set_gc_alloc_region() multiple times on
2891 // the same region
2892 assert(r == NULL || !r->is_gc_alloc_region(),
2893 "shouldn't already be a GC alloc region");
2894 HeapWord* original_top = NULL;
2895 if (r != NULL)
2896 original_top = r->top();
2898 // We will want to record the used space in r as being there before gc.
2899 // One we install it as a GC alloc region it's eligible for allocation.
2900 // So record it now and use it later.
2901 size_t r_used = 0;
2902 if (r != NULL) {
2903 r_used = r->used();
2905 if (ParallelGCThreads > 0) {
2906 // need to take the lock to guard against two threads calling
2907 // get_gc_alloc_region concurrently (very unlikely but...)
2908 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2909 r->save_marks();
2910 }
2911 }
2912 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2913 _gc_alloc_regions[purpose] = r;
2914 if (old_alloc_region != NULL) {
2915 // Replace aliases too.
2916 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2917 if (_gc_alloc_regions[ap] == old_alloc_region) {
2918 _gc_alloc_regions[ap] = r;
2919 }
2920 }
2921 }
2922 if (r != NULL) {
2923 push_gc_alloc_region(r);
2924 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2925 // We are using a region as a GC alloc region after it has been used
2926 // as a mutator allocation region during the current marking cycle.
2927 // The mutator-allocated objects are currently implicitly marked, but
2928 // when we move hr->next_top_at_mark_start() forward at the the end
2929 // of the GC pause, they won't be. We therefore mark all objects in
2930 // the "gap". We do this object-by-object, since marking densely
2931 // does not currently work right with marking bitmap iteration. This
2932 // means we rely on TLAB filling at the start of pauses, and no
2933 // "resuscitation" of filled TLAB's. If we want to do this, we need
2934 // to fix the marking bitmap iteration.
2935 HeapWord* curhw = r->next_top_at_mark_start();
2936 HeapWord* t = original_top;
2938 while (curhw < t) {
2939 oop cur = (oop)curhw;
2940 // We'll assume parallel for generality. This is rare code.
2941 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2942 curhw = curhw + cur->size();
2943 }
2944 assert(curhw == t, "Should have parsed correctly.");
2945 }
2946 if (G1PolicyVerbose > 1) {
2947 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2948 "for survivors:", r->bottom(), original_top, r->end());
2949 r->print();
2950 }
2951 g1_policy()->record_before_bytes(r_used);
2952 }
2953 }
2955 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2956 assert(Thread::current()->is_VM_thread() ||
2957 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2958 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2959 "Precondition.");
2960 hr->set_is_gc_alloc_region(true);
2961 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2962 _gc_alloc_region_list = hr;
2963 }
2965 #ifdef G1_DEBUG
2966 class FindGCAllocRegion: public HeapRegionClosure {
2967 public:
2968 bool doHeapRegion(HeapRegion* r) {
2969 if (r->is_gc_alloc_region()) {
2970 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2971 r->hrs_index(), r->bottom());
2972 }
2973 return false;
2974 }
2975 };
2976 #endif // G1_DEBUG
2978 void G1CollectedHeap::forget_alloc_region_list() {
2979 assert(Thread::current()->is_VM_thread(), "Precondition");
2980 while (_gc_alloc_region_list != NULL) {
2981 HeapRegion* r = _gc_alloc_region_list;
2982 assert(r->is_gc_alloc_region(), "Invariant.");
2983 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
2984 // newly allocated data in order to be able to apply deferred updates
2985 // before the GC is done for verification purposes (i.e to allow
2986 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
2987 // collection.
2988 r->ContiguousSpace::set_saved_mark();
2989 _gc_alloc_region_list = r->next_gc_alloc_region();
2990 r->set_next_gc_alloc_region(NULL);
2991 r->set_is_gc_alloc_region(false);
2992 if (r->is_survivor()) {
2993 if (r->is_empty()) {
2994 r->set_not_young();
2995 } else {
2996 _young_list->add_survivor_region(r);
2997 }
2998 }
2999 if (r->is_empty()) {
3000 ++_free_regions;
3001 }
3002 }
3003 #ifdef G1_DEBUG
3004 FindGCAllocRegion fa;
3005 heap_region_iterate(&fa);
3006 #endif // G1_DEBUG
3007 }
3010 bool G1CollectedHeap::check_gc_alloc_regions() {
3011 // TODO: allocation regions check
3012 return true;
3013 }
3015 void G1CollectedHeap::get_gc_alloc_regions() {
3016 // First, let's check that the GC alloc region list is empty (it should)
3017 assert(_gc_alloc_region_list == NULL, "invariant");
3019 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3020 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3021 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3023 // Create new GC alloc regions.
3024 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3025 _retained_gc_alloc_regions[ap] = NULL;
3027 if (alloc_region != NULL) {
3028 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3030 // let's make sure that the GC alloc region is not tagged as such
3031 // outside a GC operation
3032 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3034 if (alloc_region->in_collection_set() ||
3035 alloc_region->top() == alloc_region->end() ||
3036 alloc_region->top() == alloc_region->bottom()) {
3037 // we will discard the current GC alloc region if it's in the
3038 // collection set (it can happen!), if it's already full (no
3039 // point in using it), or if it's empty (this means that it
3040 // was emptied during a cleanup and it should be on the free
3041 // list now).
3043 alloc_region = NULL;
3044 }
3045 }
3047 if (alloc_region == NULL) {
3048 // we will get a new GC alloc region
3049 alloc_region = newAllocRegionWithExpansion(ap, 0);
3050 } else {
3051 // the region was retained from the last collection
3052 ++_gc_alloc_region_counts[ap];
3053 }
3055 if (alloc_region != NULL) {
3056 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3057 set_gc_alloc_region(ap, alloc_region);
3058 }
3060 assert(_gc_alloc_regions[ap] == NULL ||
3061 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3062 "the GC alloc region should be tagged as such");
3063 assert(_gc_alloc_regions[ap] == NULL ||
3064 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3065 "the GC alloc region should be the same as the GC alloc list head");
3066 }
3067 // Set alternative regions for allocation purposes that have reached
3068 // their limit.
3069 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3070 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3071 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3072 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3073 }
3074 }
3075 assert(check_gc_alloc_regions(), "alloc regions messed up");
3076 }
3078 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3079 // We keep a separate list of all regions that have been alloc regions in
3080 // the current collection pause. Forget that now. This method will
3081 // untag the GC alloc regions and tear down the GC alloc region
3082 // list. It's desirable that no regions are tagged as GC alloc
3083 // outside GCs.
3084 forget_alloc_region_list();
3086 // The current alloc regions contain objs that have survived
3087 // collection. Make them no longer GC alloc regions.
3088 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3089 HeapRegion* r = _gc_alloc_regions[ap];
3090 _retained_gc_alloc_regions[ap] = NULL;
3091 _gc_alloc_region_counts[ap] = 0;
3093 if (r != NULL) {
3094 // we retain nothing on _gc_alloc_regions between GCs
3095 set_gc_alloc_region(ap, NULL);
3097 if (r->is_empty()) {
3098 // we didn't actually allocate anything in it; let's just put
3099 // it on the free list
3100 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3101 r->set_zero_fill_complete();
3102 put_free_region_on_list_locked(r);
3103 } else if (_retain_gc_alloc_region[ap] && !totally) {
3104 // retain it so that we can use it at the beginning of the next GC
3105 _retained_gc_alloc_regions[ap] = r;
3106 }
3107 }
3108 }
3109 }
3111 #ifndef PRODUCT
3112 // Useful for debugging
3114 void G1CollectedHeap::print_gc_alloc_regions() {
3115 gclog_or_tty->print_cr("GC alloc regions");
3116 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3117 HeapRegion* r = _gc_alloc_regions[ap];
3118 if (r == NULL) {
3119 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3120 } else {
3121 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3122 ap, r->bottom(), r->used());
3123 }
3124 }
3125 }
3126 #endif // PRODUCT
3128 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3129 _drain_in_progress = false;
3130 set_evac_failure_closure(cl);
3131 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3132 }
3134 void G1CollectedHeap::finalize_for_evac_failure() {
3135 assert(_evac_failure_scan_stack != NULL &&
3136 _evac_failure_scan_stack->length() == 0,
3137 "Postcondition");
3138 assert(!_drain_in_progress, "Postcondition");
3139 // Don't have to delete, since the scan stack is a resource object.
3140 _evac_failure_scan_stack = NULL;
3141 }
3145 // *** Sequential G1 Evacuation
3147 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3148 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3149 // let the caller handle alloc failure
3150 if (alloc_region == NULL) return NULL;
3151 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3152 "Either the object is humongous or the region isn't");
3153 HeapWord* block = alloc_region->allocate(word_size);
3154 if (block == NULL) {
3155 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3156 }
3157 return block;
3158 }
3160 class G1IsAliveClosure: public BoolObjectClosure {
3161 G1CollectedHeap* _g1;
3162 public:
3163 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3164 void do_object(oop p) { assert(false, "Do not call."); }
3165 bool do_object_b(oop p) {
3166 // It is reachable if it is outside the collection set, or is inside
3167 // and forwarded.
3169 #ifdef G1_DEBUG
3170 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3171 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3172 !_g1->obj_in_cs(p) || p->is_forwarded());
3173 #endif // G1_DEBUG
3175 return !_g1->obj_in_cs(p) || p->is_forwarded();
3176 }
3177 };
3179 class G1KeepAliveClosure: public OopClosure {
3180 G1CollectedHeap* _g1;
3181 public:
3182 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3183 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3184 void do_oop( oop* p) {
3185 oop obj = *p;
3186 #ifdef G1_DEBUG
3187 if (PrintGC && Verbose) {
3188 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3189 p, (void*) obj, (void*) *p);
3190 }
3191 #endif // G1_DEBUG
3193 if (_g1->obj_in_cs(obj)) {
3194 assert( obj->is_forwarded(), "invariant" );
3195 *p = obj->forwardee();
3196 #ifdef G1_DEBUG
3197 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3198 (void*) obj, (void*) *p);
3199 #endif // G1_DEBUG
3200 }
3201 }
3202 };
3204 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3205 private:
3206 G1CollectedHeap* _g1;
3207 G1RemSet* _g1_rem_set;
3208 public:
3209 UpdateRSetImmediate(G1CollectedHeap* g1) :
3210 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3212 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3213 virtual void do_oop( oop* p) { do_oop_work(p); }
3214 template <class T> void do_oop_work(T* p) {
3215 assert(_from->is_in_reserved(p), "paranoia");
3216 T heap_oop = oopDesc::load_heap_oop(p);
3217 if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
3218 _g1_rem_set->par_write_ref(_from, p, 0);
3219 }
3220 }
3221 };
3223 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3224 private:
3225 G1CollectedHeap* _g1;
3226 DirtyCardQueue *_dcq;
3227 CardTableModRefBS* _ct_bs;
3229 public:
3230 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3231 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3233 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3234 virtual void do_oop( oop* p) { do_oop_work(p); }
3235 template <class T> void do_oop_work(T* p) {
3236 assert(_from->is_in_reserved(p), "paranoia");
3237 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3238 !_from->is_survivor()) {
3239 size_t card_index = _ct_bs->index_for(p);
3240 if (_ct_bs->mark_card_deferred(card_index)) {
3241 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3242 }
3243 }
3244 }
3245 };
3249 class RemoveSelfPointerClosure: public ObjectClosure {
3250 private:
3251 G1CollectedHeap* _g1;
3252 ConcurrentMark* _cm;
3253 HeapRegion* _hr;
3254 size_t _prev_marked_bytes;
3255 size_t _next_marked_bytes;
3256 OopsInHeapRegionClosure *_cl;
3257 public:
3258 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3259 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3260 _next_marked_bytes(0), _cl(cl) {}
3262 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3263 size_t next_marked_bytes() { return _next_marked_bytes; }
3265 // The original idea here was to coalesce evacuated and dead objects.
3266 // However that caused complications with the block offset table (BOT).
3267 // In particular if there were two TLABs, one of them partially refined.
3268 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3269 // The BOT entries of the unrefined part of TLAB_2 point to the start
3270 // of TLAB_2. If the last object of the TLAB_1 and the first object
3271 // of TLAB_2 are coalesced, then the cards of the unrefined part
3272 // would point into middle of the filler object.
3273 //
3274 // The current approach is to not coalesce and leave the BOT contents intact.
3275 void do_object(oop obj) {
3276 if (obj->is_forwarded() && obj->forwardee() == obj) {
3277 // The object failed to move.
3278 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3279 _cm->markPrev(obj);
3280 assert(_cm->isPrevMarked(obj), "Should be marked!");
3281 _prev_marked_bytes += (obj->size() * HeapWordSize);
3282 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3283 _cm->markAndGrayObjectIfNecessary(obj);
3284 }
3285 obj->set_mark(markOopDesc::prototype());
3286 // While we were processing RSet buffers during the
3287 // collection, we actually didn't scan any cards on the
3288 // collection set, since we didn't want to update remebered
3289 // sets with entries that point into the collection set, given
3290 // that live objects fromthe collection set are about to move
3291 // and such entries will be stale very soon. This change also
3292 // dealt with a reliability issue which involved scanning a
3293 // card in the collection set and coming across an array that
3294 // was being chunked and looking malformed. The problem is
3295 // that, if evacuation fails, we might have remembered set
3296 // entries missing given that we skipped cards on the
3297 // collection set. So, we'll recreate such entries now.
3298 obj->oop_iterate(_cl);
3299 assert(_cm->isPrevMarked(obj), "Should be marked!");
3300 } else {
3301 // The object has been either evacuated or is dead. Fill it with a
3302 // dummy object.
3303 MemRegion mr((HeapWord*)obj, obj->size());
3304 CollectedHeap::fill_with_object(mr);
3305 _cm->clearRangeBothMaps(mr);
3306 }
3307 }
3308 };
3310 void G1CollectedHeap::remove_self_forwarding_pointers() {
3311 UpdateRSetImmediate immediate_update(_g1h);
3312 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3313 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3314 OopsInHeapRegionClosure *cl;
3315 if (G1DeferredRSUpdate) {
3316 cl = &deferred_update;
3317 } else {
3318 cl = &immediate_update;
3319 }
3320 HeapRegion* cur = g1_policy()->collection_set();
3321 while (cur != NULL) {
3322 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3324 RemoveSelfPointerClosure rspc(_g1h, cl);
3325 if (cur->evacuation_failed()) {
3326 assert(cur->in_collection_set(), "bad CS");
3327 cl->set_region(cur);
3328 cur->object_iterate(&rspc);
3330 // A number of manipulations to make the TAMS be the current top,
3331 // and the marked bytes be the ones observed in the iteration.
3332 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3333 // The comments below are the postconditions achieved by the
3334 // calls. Note especially the last such condition, which says that
3335 // the count of marked bytes has been properly restored.
3336 cur->note_start_of_marking(false);
3337 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3338 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3339 // _next_marked_bytes == prev_marked_bytes.
3340 cur->note_end_of_marking();
3341 // _prev_top_at_mark_start == top(),
3342 // _prev_marked_bytes == prev_marked_bytes
3343 }
3344 // If there is no mark in progress, we modified the _next variables
3345 // above needlessly, but harmlessly.
3346 if (_g1h->mark_in_progress()) {
3347 cur->note_start_of_marking(false);
3348 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3349 // _next_marked_bytes == next_marked_bytes.
3350 }
3352 // Now make sure the region has the right index in the sorted array.
3353 g1_policy()->note_change_in_marked_bytes(cur);
3354 }
3355 cur = cur->next_in_collection_set();
3356 }
3357 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3359 // Now restore saved marks, if any.
3360 if (_objs_with_preserved_marks != NULL) {
3361 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3362 assert(_objs_with_preserved_marks->length() ==
3363 _preserved_marks_of_objs->length(), "Both or none.");
3364 guarantee(_objs_with_preserved_marks->length() ==
3365 _preserved_marks_of_objs->length(), "Both or none.");
3366 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3367 oop obj = _objs_with_preserved_marks->at(i);
3368 markOop m = _preserved_marks_of_objs->at(i);
3369 obj->set_mark(m);
3370 }
3371 // Delete the preserved marks growable arrays (allocated on the C heap).
3372 delete _objs_with_preserved_marks;
3373 delete _preserved_marks_of_objs;
3374 _objs_with_preserved_marks = NULL;
3375 _preserved_marks_of_objs = NULL;
3376 }
3377 }
3379 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3380 _evac_failure_scan_stack->push(obj);
3381 }
3383 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3384 assert(_evac_failure_scan_stack != NULL, "precondition");
3386 while (_evac_failure_scan_stack->length() > 0) {
3387 oop obj = _evac_failure_scan_stack->pop();
3388 _evac_failure_closure->set_region(heap_region_containing(obj));
3389 obj->oop_iterate_backwards(_evac_failure_closure);
3390 }
3391 }
3393 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3394 markOop m = old->mark();
3395 // forward to self
3396 assert(!old->is_forwarded(), "precondition");
3398 old->forward_to(old);
3399 handle_evacuation_failure_common(old, m);
3400 }
3402 oop
3403 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3404 oop old) {
3405 markOop m = old->mark();
3406 oop forward_ptr = old->forward_to_atomic(old);
3407 if (forward_ptr == NULL) {
3408 // Forward-to-self succeeded.
3409 if (_evac_failure_closure != cl) {
3410 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3411 assert(!_drain_in_progress,
3412 "Should only be true while someone holds the lock.");
3413 // Set the global evac-failure closure to the current thread's.
3414 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3415 set_evac_failure_closure(cl);
3416 // Now do the common part.
3417 handle_evacuation_failure_common(old, m);
3418 // Reset to NULL.
3419 set_evac_failure_closure(NULL);
3420 } else {
3421 // The lock is already held, and this is recursive.
3422 assert(_drain_in_progress, "This should only be the recursive case.");
3423 handle_evacuation_failure_common(old, m);
3424 }
3425 return old;
3426 } else {
3427 // Someone else had a place to copy it.
3428 return forward_ptr;
3429 }
3430 }
3432 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3433 set_evacuation_failed(true);
3435 preserve_mark_if_necessary(old, m);
3437 HeapRegion* r = heap_region_containing(old);
3438 if (!r->evacuation_failed()) {
3439 r->set_evacuation_failed(true);
3440 if (G1PrintRegions) {
3441 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3442 "["PTR_FORMAT","PTR_FORMAT")\n",
3443 r, r->bottom(), r->end());
3444 }
3445 }
3447 push_on_evac_failure_scan_stack(old);
3449 if (!_drain_in_progress) {
3450 // prevent recursion in copy_to_survivor_space()
3451 _drain_in_progress = true;
3452 drain_evac_failure_scan_stack();
3453 _drain_in_progress = false;
3454 }
3455 }
3457 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3458 if (m != markOopDesc::prototype()) {
3459 if (_objs_with_preserved_marks == NULL) {
3460 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3461 _objs_with_preserved_marks =
3462 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3463 _preserved_marks_of_objs =
3464 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3465 }
3466 _objs_with_preserved_marks->push(obj);
3467 _preserved_marks_of_objs->push(m);
3468 }
3469 }
3471 // *** Parallel G1 Evacuation
3473 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3474 size_t word_size) {
3475 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3476 // let the caller handle alloc failure
3477 if (alloc_region == NULL) return NULL;
3479 HeapWord* block = alloc_region->par_allocate(word_size);
3480 if (block == NULL) {
3481 MutexLockerEx x(par_alloc_during_gc_lock(),
3482 Mutex::_no_safepoint_check_flag);
3483 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3484 }
3485 return block;
3486 }
3488 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3489 bool par) {
3490 // Another thread might have obtained alloc_region for the given
3491 // purpose, and might be attempting to allocate in it, and might
3492 // succeed. Therefore, we can't do the "finalization" stuff on the
3493 // region below until we're sure the last allocation has happened.
3494 // We ensure this by allocating the remaining space with a garbage
3495 // object.
3496 if (par) par_allocate_remaining_space(alloc_region);
3497 // Now we can do the post-GC stuff on the region.
3498 alloc_region->note_end_of_copying();
3499 g1_policy()->record_after_bytes(alloc_region->used());
3500 }
3502 HeapWord*
3503 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3504 HeapRegion* alloc_region,
3505 bool par,
3506 size_t word_size) {
3507 HeapWord* block = NULL;
3508 // In the parallel case, a previous thread to obtain the lock may have
3509 // already assigned a new gc_alloc_region.
3510 if (alloc_region != _gc_alloc_regions[purpose]) {
3511 assert(par, "But should only happen in parallel case.");
3512 alloc_region = _gc_alloc_regions[purpose];
3513 if (alloc_region == NULL) return NULL;
3514 block = alloc_region->par_allocate(word_size);
3515 if (block != NULL) return block;
3516 // Otherwise, continue; this new region is empty, too.
3517 }
3518 assert(alloc_region != NULL, "We better have an allocation region");
3519 retire_alloc_region(alloc_region, par);
3521 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3522 // Cannot allocate more regions for the given purpose.
3523 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3524 // Is there an alternative?
3525 if (purpose != alt_purpose) {
3526 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3527 // Has not the alternative region been aliased?
3528 if (alloc_region != alt_region && alt_region != NULL) {
3529 // Try to allocate in the alternative region.
3530 if (par) {
3531 block = alt_region->par_allocate(word_size);
3532 } else {
3533 block = alt_region->allocate(word_size);
3534 }
3535 // Make an alias.
3536 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3537 if (block != NULL) {
3538 return block;
3539 }
3540 retire_alloc_region(alt_region, par);
3541 }
3542 // Both the allocation region and the alternative one are full
3543 // and aliased, replace them with a new allocation region.
3544 purpose = alt_purpose;
3545 } else {
3546 set_gc_alloc_region(purpose, NULL);
3547 return NULL;
3548 }
3549 }
3551 // Now allocate a new region for allocation.
3552 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3554 // let the caller handle alloc failure
3555 if (alloc_region != NULL) {
3557 assert(check_gc_alloc_regions(), "alloc regions messed up");
3558 assert(alloc_region->saved_mark_at_top(),
3559 "Mark should have been saved already.");
3560 // We used to assert that the region was zero-filled here, but no
3561 // longer.
3563 // This must be done last: once it's installed, other regions may
3564 // allocate in it (without holding the lock.)
3565 set_gc_alloc_region(purpose, alloc_region);
3567 if (par) {
3568 block = alloc_region->par_allocate(word_size);
3569 } else {
3570 block = alloc_region->allocate(word_size);
3571 }
3572 // Caller handles alloc failure.
3573 } else {
3574 // This sets other apis using the same old alloc region to NULL, also.
3575 set_gc_alloc_region(purpose, NULL);
3576 }
3577 return block; // May be NULL.
3578 }
3580 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3581 HeapWord* block = NULL;
3582 size_t free_words;
3583 do {
3584 free_words = r->free()/HeapWordSize;
3585 // If there's too little space, no one can allocate, so we're done.
3586 if (free_words < (size_t)oopDesc::header_size()) return;
3587 // Otherwise, try to claim it.
3588 block = r->par_allocate(free_words);
3589 } while (block == NULL);
3590 fill_with_object(block, free_words);
3591 }
3593 #ifndef PRODUCT
3594 bool GCLabBitMapClosure::do_bit(size_t offset) {
3595 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3596 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3597 return true;
3598 }
3599 #endif // PRODUCT
3601 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3602 : _g1h(g1h),
3603 _refs(g1h->task_queue(queue_num)),
3604 _dcq(&g1h->dirty_card_queue_set()),
3605 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3606 _g1_rem(g1h->g1_rem_set()),
3607 _hash_seed(17), _queue_num(queue_num),
3608 _term_attempts(0),
3609 _age_table(false),
3610 #if G1_DETAILED_STATS
3611 _pushes(0), _pops(0), _steals(0),
3612 _steal_attempts(0), _overflow_pushes(0),
3613 #endif
3614 _strong_roots_time(0), _term_time(0),
3615 _alloc_buffer_waste(0), _undo_waste(0)
3616 {
3617 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3618 // we "sacrifice" entry 0 to keep track of surviving bytes for
3619 // non-young regions (where the age is -1)
3620 // We also add a few elements at the beginning and at the end in
3621 // an attempt to eliminate cache contention
3622 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3623 size_t array_length = PADDING_ELEM_NUM +
3624 real_length +
3625 PADDING_ELEM_NUM;
3626 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3627 if (_surviving_young_words_base == NULL)
3628 vm_exit_out_of_memory(array_length * sizeof(size_t),
3629 "Not enough space for young surv histo.");
3630 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3631 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3633 _overflowed_refs = new OverflowQueue(10);
3635 _start = os::elapsedTime();
3636 }
3638 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3639 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3640 _par_scan_state(par_scan_state) { }
3642 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3643 // This is called _after_ do_oop_work has been called, hence after
3644 // the object has been relocated to its new location and *p points
3645 // to its new location.
3647 T heap_oop = oopDesc::load_heap_oop(p);
3648 if (!oopDesc::is_null(heap_oop)) {
3649 oop obj = oopDesc::decode_heap_oop(heap_oop);
3650 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3651 "shouldn't still be in the CSet if evacuation didn't fail.");
3652 HeapWord* addr = (HeapWord*)obj;
3653 if (_g1->is_in_g1_reserved(addr))
3654 _cm->grayRoot(oop(addr));
3655 }
3656 }
3658 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3659 size_t word_sz = old->size();
3660 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3661 // +1 to make the -1 indexes valid...
3662 int young_index = from_region->young_index_in_cset()+1;
3663 assert( (from_region->is_young() && young_index > 0) ||
3664 (!from_region->is_young() && young_index == 0), "invariant" );
3665 G1CollectorPolicy* g1p = _g1->g1_policy();
3666 markOop m = old->mark();
3667 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3668 : m->age();
3669 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3670 word_sz);
3671 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3672 oop obj = oop(obj_ptr);
3674 if (obj_ptr == NULL) {
3675 // This will either forward-to-self, or detect that someone else has
3676 // installed a forwarding pointer.
3677 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3678 return _g1->handle_evacuation_failure_par(cl, old);
3679 }
3681 // We're going to allocate linearly, so might as well prefetch ahead.
3682 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3684 oop forward_ptr = old->forward_to_atomic(obj);
3685 if (forward_ptr == NULL) {
3686 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3687 if (g1p->track_object_age(alloc_purpose)) {
3688 // We could simply do obj->incr_age(). However, this causes a
3689 // performance issue. obj->incr_age() will first check whether
3690 // the object has a displaced mark by checking its mark word;
3691 // getting the mark word from the new location of the object
3692 // stalls. So, given that we already have the mark word and we
3693 // are about to install it anyway, it's better to increase the
3694 // age on the mark word, when the object does not have a
3695 // displaced mark word. We're not expecting many objects to have
3696 // a displaced marked word, so that case is not optimized
3697 // further (it could be...) and we simply call obj->incr_age().
3699 if (m->has_displaced_mark_helper()) {
3700 // in this case, we have to install the mark word first,
3701 // otherwise obj looks to be forwarded (the old mark word,
3702 // which contains the forward pointer, was copied)
3703 obj->set_mark(m);
3704 obj->incr_age();
3705 } else {
3706 m = m->incr_age();
3707 obj->set_mark(m);
3708 }
3709 _par_scan_state->age_table()->add(obj, word_sz);
3710 } else {
3711 obj->set_mark(m);
3712 }
3714 // preserve "next" mark bit
3715 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3716 if (!use_local_bitmaps ||
3717 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3718 // if we couldn't mark it on the local bitmap (this happens when
3719 // the object was not allocated in the GCLab), we have to bite
3720 // the bullet and do the standard parallel mark
3721 _cm->markAndGrayObjectIfNecessary(obj);
3722 }
3723 #if 1
3724 if (_g1->isMarkedNext(old)) {
3725 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3726 }
3727 #endif
3728 }
3730 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3731 surv_young_words[young_index] += word_sz;
3733 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3734 arrayOop(old)->set_length(0);
3735 oop* old_p = set_partial_array_mask(old);
3736 _par_scan_state->push_on_queue(old_p);
3737 } else {
3738 // No point in using the slower heap_region_containing() method,
3739 // given that we know obj is in the heap.
3740 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3741 obj->oop_iterate_backwards(_scanner);
3742 }
3743 } else {
3744 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3745 obj = forward_ptr;
3746 }
3747 return obj;
3748 }
3750 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee, bool skip_cset_test>
3751 template <class T>
3752 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee, skip_cset_test>
3753 ::do_oop_work(T* p) {
3754 oop obj = oopDesc::load_decode_heap_oop(p);
3755 assert(barrier != G1BarrierRS || obj != NULL,
3756 "Precondition: G1BarrierRS implies obj is nonNull");
3758 // The only time we skip the cset test is when we're scanning
3759 // references popped from the queue. And we only push on the queue
3760 // references that we know point into the cset, so no point in
3761 // checking again. But we'll leave an assert here for peace of mind.
3762 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
3764 // here the null check is implicit in the cset_fast_test() test
3765 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
3766 #if G1_REM_SET_LOGGING
3767 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
3768 "into CS.", p, (void*) obj);
3769 #endif
3770 if (obj->is_forwarded()) {
3771 oopDesc::encode_store_heap_oop(p, obj->forwardee());
3772 } else {
3773 oop copy_oop = copy_to_survivor_space(obj);
3774 oopDesc::encode_store_heap_oop(p, copy_oop);
3775 }
3776 // When scanning the RS, we only care about objs in CS.
3777 if (barrier == G1BarrierRS) {
3778 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3779 }
3780 }
3782 // When scanning moved objs, must look at all oops.
3783 if (barrier == G1BarrierEvac && obj != NULL) {
3784 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3785 }
3787 if (do_gen_barrier && obj != NULL) {
3788 par_do_barrier(p);
3789 }
3790 }
3792 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
3793 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(narrowOop* p);
3795 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
3796 assert(has_partial_array_mask(p), "invariant");
3797 oop old = clear_partial_array_mask(p);
3798 assert(old->is_objArray(), "must be obj array");
3799 assert(old->is_forwarded(), "must be forwarded");
3800 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
3802 objArrayOop obj = objArrayOop(old->forwardee());
3803 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
3804 // Process ParGCArrayScanChunk elements now
3805 // and push the remainder back onto queue
3806 int start = arrayOop(old)->length();
3807 int end = obj->length();
3808 int remainder = end - start;
3809 assert(start <= end, "just checking");
3810 if (remainder > 2 * ParGCArrayScanChunk) {
3811 // Test above combines last partial chunk with a full chunk
3812 end = start + ParGCArrayScanChunk;
3813 arrayOop(old)->set_length(end);
3814 // Push remainder.
3815 oop* old_p = set_partial_array_mask(old);
3816 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
3817 _par_scan_state->push_on_queue(old_p);
3818 } else {
3819 // Restore length so that the heap remains parsable in
3820 // case of evacuation failure.
3821 arrayOop(old)->set_length(end);
3822 }
3823 _scanner.set_region(_g1->heap_region_containing_raw(obj));
3824 // process our set of indices (include header in first chunk)
3825 obj->oop_iterate_range(&_scanner, start, end);
3826 }
3828 class G1ParEvacuateFollowersClosure : public VoidClosure {
3829 protected:
3830 G1CollectedHeap* _g1h;
3831 G1ParScanThreadState* _par_scan_state;
3832 RefToScanQueueSet* _queues;
3833 ParallelTaskTerminator* _terminator;
3835 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3836 RefToScanQueueSet* queues() { return _queues; }
3837 ParallelTaskTerminator* terminator() { return _terminator; }
3839 public:
3840 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
3841 G1ParScanThreadState* par_scan_state,
3842 RefToScanQueueSet* queues,
3843 ParallelTaskTerminator* terminator)
3844 : _g1h(g1h), _par_scan_state(par_scan_state),
3845 _queues(queues), _terminator(terminator) {}
3847 void do_void() {
3848 G1ParScanThreadState* pss = par_scan_state();
3849 while (true) {
3850 pss->trim_queue();
3851 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
3853 StarTask stolen_task;
3854 if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
3855 IF_G1_DETAILED_STATS(pss->note_steal());
3857 // slightly paranoid tests; I'm trying to catch potential
3858 // problems before we go into push_on_queue to know where the
3859 // problem is coming from
3860 assert((oop*)stolen_task != NULL, "Error");
3861 if (stolen_task.is_narrow()) {
3862 assert(UseCompressedOops, "Error");
3863 narrowOop* p = (narrowOop*) stolen_task;
3864 assert(has_partial_array_mask(p) ||
3865 _g1h->obj_in_cs(oopDesc::load_decode_heap_oop(p)), "Error");
3866 pss->push_on_queue(p);
3867 } else {
3868 oop* p = (oop*) stolen_task;
3869 assert(has_partial_array_mask(p) || _g1h->obj_in_cs(*p), "Error");
3870 pss->push_on_queue(p);
3871 }
3872 continue;
3873 }
3874 pss->start_term_time();
3875 if (terminator()->offer_termination()) break;
3876 pss->end_term_time();
3877 }
3878 pss->end_term_time();
3879 pss->retire_alloc_buffers();
3880 }
3881 };
3883 class G1ParTask : public AbstractGangTask {
3884 protected:
3885 G1CollectedHeap* _g1h;
3886 RefToScanQueueSet *_queues;
3887 ParallelTaskTerminator _terminator;
3888 int _n_workers;
3890 Mutex _stats_lock;
3891 Mutex* stats_lock() { return &_stats_lock; }
3893 size_t getNCards() {
3894 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
3895 / G1BlockOffsetSharedArray::N_bytes;
3896 }
3898 public:
3899 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
3900 : AbstractGangTask("G1 collection"),
3901 _g1h(g1h),
3902 _queues(task_queues),
3903 _terminator(workers, _queues),
3904 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
3905 _n_workers(workers)
3906 {}
3908 RefToScanQueueSet* queues() { return _queues; }
3910 RefToScanQueue *work_queue(int i) {
3911 return queues()->queue(i);
3912 }
3914 void work(int i) {
3915 if (i >= _n_workers) return; // no work needed this round
3916 ResourceMark rm;
3917 HandleMark hm;
3919 G1ParScanThreadState pss(_g1h, i);
3920 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
3921 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
3922 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
3924 pss.set_evac_closure(&scan_evac_cl);
3925 pss.set_evac_failure_closure(&evac_failure_cl);
3926 pss.set_partial_scan_closure(&partial_scan_cl);
3928 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
3929 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
3930 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
3932 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
3933 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
3934 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
3936 OopsInHeapRegionClosure *scan_root_cl;
3937 OopsInHeapRegionClosure *scan_perm_cl;
3938 OopsInHeapRegionClosure *scan_so_cl;
3940 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
3941 scan_root_cl = &scan_mark_root_cl;
3942 scan_perm_cl = &scan_mark_perm_cl;
3943 scan_so_cl = &scan_mark_heap_rs_cl;
3944 } else {
3945 scan_root_cl = &only_scan_root_cl;
3946 scan_perm_cl = &only_scan_perm_cl;
3947 scan_so_cl = &only_scan_heap_rs_cl;
3948 }
3950 pss.start_strong_roots();
3951 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
3952 SharedHeap::SO_AllClasses,
3953 scan_root_cl,
3954 &only_scan_heap_rs_cl,
3955 scan_so_cl,
3956 scan_perm_cl,
3957 i);
3958 pss.end_strong_roots();
3959 {
3960 double start = os::elapsedTime();
3961 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
3962 evac.do_void();
3963 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
3964 double term_ms = pss.term_time()*1000.0;
3965 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
3966 _g1h->g1_policy()->record_termination_time(i, term_ms);
3967 }
3968 if (G1UseSurvivorSpaces) {
3969 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
3970 }
3971 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
3973 // Clean up any par-expanded rem sets.
3974 HeapRegionRemSet::par_cleanup();
3976 MutexLocker x(stats_lock());
3977 if (ParallelGCVerbose) {
3978 gclog_or_tty->print("Thread %d complete:\n", i);
3979 #if G1_DETAILED_STATS
3980 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
3981 pss.pushes(),
3982 pss.pops(),
3983 pss.overflow_pushes(),
3984 pss.steals(),
3985 pss.steal_attempts());
3986 #endif
3987 double elapsed = pss.elapsed();
3988 double strong_roots = pss.strong_roots_time();
3989 double term = pss.term_time();
3990 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
3991 " Strong roots: %7.2f ms (%6.2f%%)\n"
3992 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
3993 elapsed * 1000.0,
3994 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
3995 term * 1000.0, (term*100.0/elapsed),
3996 pss.term_attempts());
3997 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
3998 gclog_or_tty->print(" Waste: %8dK\n"
3999 " Alloc Buffer: %8dK\n"
4000 " Undo: %8dK\n",
4001 (total_waste * HeapWordSize) / K,
4002 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4003 (pss.undo_waste() * HeapWordSize) / K);
4004 }
4006 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4007 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4008 }
4009 };
4011 // *** Common G1 Evacuation Stuff
4013 void
4014 G1CollectedHeap::
4015 g1_process_strong_roots(bool collecting_perm_gen,
4016 SharedHeap::ScanningOption so,
4017 OopClosure* scan_non_heap_roots,
4018 OopsInHeapRegionClosure* scan_rs,
4019 OopsInHeapRegionClosure* scan_so,
4020 OopsInGenClosure* scan_perm,
4021 int worker_i) {
4022 // First scan the strong roots, including the perm gen.
4023 double ext_roots_start = os::elapsedTime();
4024 double closure_app_time_sec = 0.0;
4026 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4027 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4028 buf_scan_perm.set_generation(perm_gen());
4030 // Walk the code cache w/o buffering, because StarTask cannot handle
4031 // unaligned oop locations.
4032 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4034 process_strong_roots(false, // no scoping; this is parallel code
4035 collecting_perm_gen, so,
4036 &buf_scan_non_heap_roots,
4037 &eager_scan_code_roots,
4038 &buf_scan_perm);
4039 // Finish up any enqueued closure apps.
4040 buf_scan_non_heap_roots.done();
4041 buf_scan_perm.done();
4042 double ext_roots_end = os::elapsedTime();
4043 g1_policy()->reset_obj_copy_time(worker_i);
4044 double obj_copy_time_sec =
4045 buf_scan_non_heap_roots.closure_app_seconds() +
4046 buf_scan_perm.closure_app_seconds();
4047 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4048 double ext_root_time_ms =
4049 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4050 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4052 // Scan strong roots in mark stack.
4053 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4054 concurrent_mark()->oops_do(scan_non_heap_roots);
4055 }
4056 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4057 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4059 // XXX What should this be doing in the parallel case?
4060 g1_policy()->record_collection_pause_end_CH_strong_roots();
4061 if (scan_so != NULL) {
4062 scan_scan_only_set(scan_so, worker_i);
4063 }
4064 // Now scan the complement of the collection set.
4065 if (scan_rs != NULL) {
4066 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4067 }
4068 // Finish with the ref_processor roots.
4069 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4070 ref_processor()->oops_do(scan_non_heap_roots);
4071 }
4072 g1_policy()->record_collection_pause_end_G1_strong_roots();
4073 _process_strong_tasks->all_tasks_completed();
4074 }
4076 void
4077 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4078 OopsInHeapRegionClosure* oc,
4079 int worker_i) {
4080 HeapWord* startAddr = r->bottom();
4081 HeapWord* endAddr = r->used_region().end();
4083 oc->set_region(r);
4085 HeapWord* p = r->bottom();
4086 HeapWord* t = r->top();
4087 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4088 while (p < t) {
4089 oop obj = oop(p);
4090 p += obj->oop_iterate(oc);
4091 }
4092 }
4094 void
4095 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4096 int worker_i) {
4097 double start = os::elapsedTime();
4099 BufferingOopsInHeapRegionClosure boc(oc);
4101 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4102 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4104 OopsInHeapRegionClosure *foc;
4105 if (g1_policy()->should_initiate_conc_mark())
4106 foc = &scan_and_mark;
4107 else
4108 foc = &scan_only;
4110 HeapRegion* hr;
4111 int n = 0;
4112 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4113 scan_scan_only_region(hr, foc, worker_i);
4114 ++n;
4115 }
4116 boc.done();
4118 double closure_app_s = boc.closure_app_seconds();
4119 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4120 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4121 g1_policy()->record_scan_only_time(worker_i, ms, n);
4122 }
4124 void
4125 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4126 OopClosure* non_root_closure) {
4127 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4128 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4129 }
4132 class SaveMarksClosure: public HeapRegionClosure {
4133 public:
4134 bool doHeapRegion(HeapRegion* r) {
4135 r->save_marks();
4136 return false;
4137 }
4138 };
4140 void G1CollectedHeap::save_marks() {
4141 if (ParallelGCThreads == 0) {
4142 SaveMarksClosure sm;
4143 heap_region_iterate(&sm);
4144 }
4145 // We do this even in the parallel case
4146 perm_gen()->save_marks();
4147 }
4149 void G1CollectedHeap::evacuate_collection_set() {
4150 set_evacuation_failed(false);
4152 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4153 concurrent_g1_refine()->set_use_cache(false);
4154 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4156 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4157 set_par_threads(n_workers);
4158 G1ParTask g1_par_task(this, n_workers, _task_queues);
4160 init_for_evac_failure(NULL);
4162 rem_set()->prepare_for_younger_refs_iterate(true);
4164 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4165 double start_par = os::elapsedTime();
4166 if (ParallelGCThreads > 0) {
4167 // The individual threads will set their evac-failure closures.
4168 StrongRootsScope srs(this);
4169 workers()->run_task(&g1_par_task);
4170 } else {
4171 StrongRootsScope srs(this);
4172 g1_par_task.work(0);
4173 }
4175 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4176 g1_policy()->record_par_time(par_time);
4177 set_par_threads(0);
4178 // Is this the right thing to do here? We don't save marks
4179 // on individual heap regions when we allocate from
4180 // them in parallel, so this seems like the correct place for this.
4181 retire_all_alloc_regions();
4182 {
4183 G1IsAliveClosure is_alive(this);
4184 G1KeepAliveClosure keep_alive(this);
4185 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4186 }
4187 release_gc_alloc_regions(false /* totally */);
4188 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4190 concurrent_g1_refine()->clear_hot_cache();
4191 concurrent_g1_refine()->set_use_cache(true);
4193 finalize_for_evac_failure();
4195 // Must do this before removing self-forwarding pointers, which clears
4196 // the per-region evac-failure flags.
4197 concurrent_mark()->complete_marking_in_collection_set();
4199 if (evacuation_failed()) {
4200 remove_self_forwarding_pointers();
4201 if (PrintGCDetails) {
4202 gclog_or_tty->print(" (evacuation failed)");
4203 } else if (PrintGC) {
4204 gclog_or_tty->print("--");
4205 }
4206 }
4208 if (G1DeferredRSUpdate) {
4209 RedirtyLoggedCardTableEntryFastClosure redirty;
4210 dirty_card_queue_set().set_closure(&redirty);
4211 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4212 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4213 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4214 }
4216 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4217 }
4219 void G1CollectedHeap::free_region(HeapRegion* hr) {
4220 size_t pre_used = 0;
4221 size_t cleared_h_regions = 0;
4222 size_t freed_regions = 0;
4223 UncleanRegionList local_list;
4225 HeapWord* start = hr->bottom();
4226 HeapWord* end = hr->prev_top_at_mark_start();
4227 size_t used_bytes = hr->used();
4228 size_t live_bytes = hr->max_live_bytes();
4229 if (used_bytes > 0) {
4230 guarantee( live_bytes <= used_bytes, "invariant" );
4231 } else {
4232 guarantee( live_bytes == 0, "invariant" );
4233 }
4235 size_t garbage_bytes = used_bytes - live_bytes;
4236 if (garbage_bytes > 0)
4237 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4239 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4240 &local_list);
4241 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4242 &local_list);
4243 }
4245 void
4246 G1CollectedHeap::free_region_work(HeapRegion* hr,
4247 size_t& pre_used,
4248 size_t& cleared_h_regions,
4249 size_t& freed_regions,
4250 UncleanRegionList* list,
4251 bool par) {
4252 pre_used += hr->used();
4253 if (hr->isHumongous()) {
4254 assert(hr->startsHumongous(),
4255 "Only the start of a humongous region should be freed.");
4256 int ind = _hrs->find(hr);
4257 assert(ind != -1, "Should have an index.");
4258 // Clear the start region.
4259 hr->hr_clear(par, true /*clear_space*/);
4260 list->insert_before_head(hr);
4261 cleared_h_regions++;
4262 freed_regions++;
4263 // Clear any continued regions.
4264 ind++;
4265 while ((size_t)ind < n_regions()) {
4266 HeapRegion* hrc = _hrs->at(ind);
4267 if (!hrc->continuesHumongous()) break;
4268 // Otherwise, does continue the H region.
4269 assert(hrc->humongous_start_region() == hr, "Huh?");
4270 hrc->hr_clear(par, true /*clear_space*/);
4271 cleared_h_regions++;
4272 freed_regions++;
4273 list->insert_before_head(hrc);
4274 ind++;
4275 }
4276 } else {
4277 hr->hr_clear(par, true /*clear_space*/);
4278 list->insert_before_head(hr);
4279 freed_regions++;
4280 // If we're using clear2, this should not be enabled.
4281 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4282 }
4283 }
4285 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4286 size_t cleared_h_regions,
4287 size_t freed_regions,
4288 UncleanRegionList* list) {
4289 if (list != NULL && list->sz() > 0) {
4290 prepend_region_list_on_unclean_list(list);
4291 }
4292 // Acquire a lock, if we're parallel, to update possibly-shared
4293 // variables.
4294 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4295 {
4296 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4297 _summary_bytes_used -= pre_used;
4298 _num_humongous_regions -= (int) cleared_h_regions;
4299 _free_regions += freed_regions;
4300 }
4301 }
4304 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4305 while (list != NULL) {
4306 guarantee( list->is_young(), "invariant" );
4308 HeapWord* bottom = list->bottom();
4309 HeapWord* end = list->end();
4310 MemRegion mr(bottom, end);
4311 ct_bs->dirty(mr);
4313 list = list->get_next_young_region();
4314 }
4315 }
4318 class G1ParCleanupCTTask : public AbstractGangTask {
4319 CardTableModRefBS* _ct_bs;
4320 G1CollectedHeap* _g1h;
4321 HeapRegion* volatile _so_head;
4322 HeapRegion* volatile _su_head;
4323 public:
4324 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4325 G1CollectedHeap* g1h,
4326 HeapRegion* scan_only_list,
4327 HeapRegion* survivor_list) :
4328 AbstractGangTask("G1 Par Cleanup CT Task"),
4329 _ct_bs(ct_bs),
4330 _g1h(g1h),
4331 _so_head(scan_only_list),
4332 _su_head(survivor_list)
4333 { }
4335 void work(int i) {
4336 HeapRegion* r;
4337 while (r = _g1h->pop_dirty_cards_region()) {
4338 clear_cards(r);
4339 }
4340 // Redirty the cards of the scan-only and survivor regions.
4341 dirty_list(&this->_so_head);
4342 dirty_list(&this->_su_head);
4343 }
4345 void clear_cards(HeapRegion* r) {
4346 // Cards for Survivor and Scan-Only regions will be dirtied later.
4347 if (!r->is_scan_only() && !r->is_survivor()) {
4348 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4349 }
4350 }
4352 void dirty_list(HeapRegion* volatile * head_ptr) {
4353 HeapRegion* head;
4354 do {
4355 // Pop region off the list.
4356 head = *head_ptr;
4357 if (head != NULL) {
4358 HeapRegion* r = (HeapRegion*)
4359 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4360 if (r == head) {
4361 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4362 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4363 }
4364 }
4365 } while (*head_ptr != NULL);
4366 }
4367 };
4370 #ifndef PRODUCT
4371 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4372 CardTableModRefBS* _ct_bs;
4373 public:
4374 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4375 : _ct_bs(ct_bs)
4376 { }
4377 virtual bool doHeapRegion(HeapRegion* r)
4378 {
4379 MemRegion mr(r->bottom(), r->end());
4380 if (r->is_scan_only() || r->is_survivor()) {
4381 _ct_bs->verify_dirty_region(mr);
4382 } else {
4383 _ct_bs->verify_clean_region(mr);
4384 }
4385 return false;
4386 }
4387 };
4388 #endif
4390 void G1CollectedHeap::cleanUpCardTable() {
4391 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4392 double start = os::elapsedTime();
4394 // Iterate over the dirty cards region list.
4395 G1ParCleanupCTTask cleanup_task(ct_bs, this,
4396 _young_list->first_scan_only_region(),
4397 _young_list->first_survivor_region());
4398 if (ParallelGCThreads > 0) {
4399 set_par_threads(workers()->total_workers());
4400 workers()->run_task(&cleanup_task);
4401 set_par_threads(0);
4402 } else {
4403 while (_dirty_cards_region_list) {
4404 HeapRegion* r = _dirty_cards_region_list;
4405 cleanup_task.clear_cards(r);
4406 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4407 if (_dirty_cards_region_list == r) {
4408 // The last region.
4409 _dirty_cards_region_list = NULL;
4410 }
4411 r->set_next_dirty_cards_region(NULL);
4412 }
4413 // now, redirty the cards of the scan-only and survivor regions
4414 // (it seemed faster to do it this way, instead of iterating over
4415 // all regions and then clearing / dirtying as appropriate)
4416 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4417 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4418 }
4419 double elapsed = os::elapsedTime() - start;
4420 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4421 #ifndef PRODUCT
4422 if (G1VerifyCTCleanup || VerifyAfterGC) {
4423 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
4424 heap_region_iterate(&cleanup_verifier);
4425 }
4426 #endif
4427 }
4429 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4430 if (g1_policy()->should_do_collection_pause(word_size)) {
4431 do_collection_pause();
4432 }
4433 }
4435 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4436 double young_time_ms = 0.0;
4437 double non_young_time_ms = 0.0;
4439 G1CollectorPolicy* policy = g1_policy();
4441 double start_sec = os::elapsedTime();
4442 bool non_young = true;
4444 HeapRegion* cur = cs_head;
4445 int age_bound = -1;
4446 size_t rs_lengths = 0;
4448 while (cur != NULL) {
4449 if (non_young) {
4450 if (cur->is_young()) {
4451 double end_sec = os::elapsedTime();
4452 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4453 non_young_time_ms += elapsed_ms;
4455 start_sec = os::elapsedTime();
4456 non_young = false;
4457 }
4458 } else {
4459 if (!cur->is_on_free_list()) {
4460 double end_sec = os::elapsedTime();
4461 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4462 young_time_ms += elapsed_ms;
4464 start_sec = os::elapsedTime();
4465 non_young = true;
4466 }
4467 }
4469 rs_lengths += cur->rem_set()->occupied();
4471 HeapRegion* next = cur->next_in_collection_set();
4472 assert(cur->in_collection_set(), "bad CS");
4473 cur->set_next_in_collection_set(NULL);
4474 cur->set_in_collection_set(false);
4476 if (cur->is_young()) {
4477 int index = cur->young_index_in_cset();
4478 guarantee( index != -1, "invariant" );
4479 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4480 size_t words_survived = _surviving_young_words[index];
4481 cur->record_surv_words_in_group(words_survived);
4482 } else {
4483 int index = cur->young_index_in_cset();
4484 guarantee( index == -1, "invariant" );
4485 }
4487 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4488 (!cur->is_young() && cur->young_index_in_cset() == -1),
4489 "invariant" );
4491 if (!cur->evacuation_failed()) {
4492 // And the region is empty.
4493 assert(!cur->is_empty(),
4494 "Should not have empty regions in a CS.");
4495 free_region(cur);
4496 } else {
4497 guarantee( !cur->is_scan_only(), "should not be scan only" );
4498 cur->uninstall_surv_rate_group();
4499 if (cur->is_young())
4500 cur->set_young_index_in_cset(-1);
4501 cur->set_not_young();
4502 cur->set_evacuation_failed(false);
4503 }
4504 cur = next;
4505 }
4507 policy->record_max_rs_lengths(rs_lengths);
4508 policy->cset_regions_freed();
4510 double end_sec = os::elapsedTime();
4511 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4512 if (non_young)
4513 non_young_time_ms += elapsed_ms;
4514 else
4515 young_time_ms += elapsed_ms;
4517 policy->record_young_free_cset_time_ms(young_time_ms);
4518 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4519 }
4521 HeapRegion*
4522 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4523 assert(ZF_mon->owned_by_self(), "Precondition");
4524 HeapRegion* res = pop_unclean_region_list_locked();
4525 if (res != NULL) {
4526 assert(!res->continuesHumongous() &&
4527 res->zero_fill_state() != HeapRegion::Allocated,
4528 "Only free regions on unclean list.");
4529 if (zero_filled) {
4530 res->ensure_zero_filled_locked();
4531 res->set_zero_fill_allocated();
4532 }
4533 }
4534 return res;
4535 }
4537 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4538 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4539 return alloc_region_from_unclean_list_locked(zero_filled);
4540 }
4542 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4543 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4544 put_region_on_unclean_list_locked(r);
4545 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4546 }
4548 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4549 MutexLockerEx x(Cleanup_mon);
4550 set_unclean_regions_coming_locked(b);
4551 }
4553 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4554 assert(Cleanup_mon->owned_by_self(), "Precondition");
4555 _unclean_regions_coming = b;
4556 // Wake up mutator threads that might be waiting for completeCleanup to
4557 // finish.
4558 if (!b) Cleanup_mon->notify_all();
4559 }
4561 void G1CollectedHeap::wait_for_cleanup_complete() {
4562 MutexLockerEx x(Cleanup_mon);
4563 wait_for_cleanup_complete_locked();
4564 }
4566 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4567 assert(Cleanup_mon->owned_by_self(), "precondition");
4568 while (_unclean_regions_coming) {
4569 Cleanup_mon->wait();
4570 }
4571 }
4573 void
4574 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4575 assert(ZF_mon->owned_by_self(), "precondition.");
4576 _unclean_region_list.insert_before_head(r);
4577 }
4579 void
4580 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4581 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4582 prepend_region_list_on_unclean_list_locked(list);
4583 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4584 }
4586 void
4587 G1CollectedHeap::
4588 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4589 assert(ZF_mon->owned_by_self(), "precondition.");
4590 _unclean_region_list.prepend_list(list);
4591 }
4593 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4594 assert(ZF_mon->owned_by_self(), "precondition.");
4595 HeapRegion* res = _unclean_region_list.pop();
4596 if (res != NULL) {
4597 // Inform ZF thread that there's a new unclean head.
4598 if (_unclean_region_list.hd() != NULL && should_zf())
4599 ZF_mon->notify_all();
4600 }
4601 return res;
4602 }
4604 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4605 assert(ZF_mon->owned_by_self(), "precondition.");
4606 return _unclean_region_list.hd();
4607 }
4610 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4611 assert(ZF_mon->owned_by_self(), "Precondition");
4612 HeapRegion* r = peek_unclean_region_list_locked();
4613 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4614 // Result of below must be equal to "r", since we hold the lock.
4615 (void)pop_unclean_region_list_locked();
4616 put_free_region_on_list_locked(r);
4617 return true;
4618 } else {
4619 return false;
4620 }
4621 }
4623 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4624 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4625 return move_cleaned_region_to_free_list_locked();
4626 }
4629 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4630 assert(ZF_mon->owned_by_self(), "precondition.");
4631 assert(_free_region_list_size == free_region_list_length(), "Inv");
4632 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4633 "Regions on free list must be zero filled");
4634 assert(!r->isHumongous(), "Must not be humongous.");
4635 assert(r->is_empty(), "Better be empty");
4636 assert(!r->is_on_free_list(),
4637 "Better not already be on free list");
4638 assert(!r->is_on_unclean_list(),
4639 "Better not already be on unclean list");
4640 r->set_on_free_list(true);
4641 r->set_next_on_free_list(_free_region_list);
4642 _free_region_list = r;
4643 _free_region_list_size++;
4644 assert(_free_region_list_size == free_region_list_length(), "Inv");
4645 }
4647 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4648 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4649 put_free_region_on_list_locked(r);
4650 }
4652 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4653 assert(ZF_mon->owned_by_self(), "precondition.");
4654 assert(_free_region_list_size == free_region_list_length(), "Inv");
4655 HeapRegion* res = _free_region_list;
4656 if (res != NULL) {
4657 _free_region_list = res->next_from_free_list();
4658 _free_region_list_size--;
4659 res->set_on_free_list(false);
4660 res->set_next_on_free_list(NULL);
4661 assert(_free_region_list_size == free_region_list_length(), "Inv");
4662 }
4663 return res;
4664 }
4667 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4668 // By self, or on behalf of self.
4669 assert(Heap_lock->is_locked(), "Precondition");
4670 HeapRegion* res = NULL;
4671 bool first = true;
4672 while (res == NULL) {
4673 if (zero_filled || !first) {
4674 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4675 res = pop_free_region_list_locked();
4676 if (res != NULL) {
4677 assert(!res->zero_fill_is_allocated(),
4678 "No allocated regions on free list.");
4679 res->set_zero_fill_allocated();
4680 } else if (!first) {
4681 break; // We tried both, time to return NULL.
4682 }
4683 }
4685 if (res == NULL) {
4686 res = alloc_region_from_unclean_list(zero_filled);
4687 }
4688 assert(res == NULL ||
4689 !zero_filled ||
4690 res->zero_fill_is_allocated(),
4691 "We must have allocated the region we're returning");
4692 first = false;
4693 }
4694 return res;
4695 }
4697 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4698 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4699 {
4700 HeapRegion* prev = NULL;
4701 HeapRegion* cur = _unclean_region_list.hd();
4702 while (cur != NULL) {
4703 HeapRegion* next = cur->next_from_unclean_list();
4704 if (cur->zero_fill_is_allocated()) {
4705 // Remove from the list.
4706 if (prev == NULL) {
4707 (void)_unclean_region_list.pop();
4708 } else {
4709 _unclean_region_list.delete_after(prev);
4710 }
4711 cur->set_on_unclean_list(false);
4712 cur->set_next_on_unclean_list(NULL);
4713 } else {
4714 prev = cur;
4715 }
4716 cur = next;
4717 }
4718 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4719 "Inv");
4720 }
4722 {
4723 HeapRegion* prev = NULL;
4724 HeapRegion* cur = _free_region_list;
4725 while (cur != NULL) {
4726 HeapRegion* next = cur->next_from_free_list();
4727 if (cur->zero_fill_is_allocated()) {
4728 // Remove from the list.
4729 if (prev == NULL) {
4730 _free_region_list = cur->next_from_free_list();
4731 } else {
4732 prev->set_next_on_free_list(cur->next_from_free_list());
4733 }
4734 cur->set_on_free_list(false);
4735 cur->set_next_on_free_list(NULL);
4736 _free_region_list_size--;
4737 } else {
4738 prev = cur;
4739 }
4740 cur = next;
4741 }
4742 assert(_free_region_list_size == free_region_list_length(), "Inv");
4743 }
4744 }
4746 bool G1CollectedHeap::verify_region_lists() {
4747 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4748 return verify_region_lists_locked();
4749 }
4751 bool G1CollectedHeap::verify_region_lists_locked() {
4752 HeapRegion* unclean = _unclean_region_list.hd();
4753 while (unclean != NULL) {
4754 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4755 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4756 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4757 "Everything else is possible.");
4758 unclean = unclean->next_from_unclean_list();
4759 }
4760 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4762 HeapRegion* free_r = _free_region_list;
4763 while (free_r != NULL) {
4764 assert(free_r->is_on_free_list(), "Well, it is!");
4765 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4766 switch (free_r->zero_fill_state()) {
4767 case HeapRegion::NotZeroFilled:
4768 case HeapRegion::ZeroFilling:
4769 guarantee(false, "Should not be on free list.");
4770 break;
4771 default:
4772 // Everything else is possible.
4773 break;
4774 }
4775 free_r = free_r->next_from_free_list();
4776 }
4777 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4778 // If we didn't do an assertion...
4779 return true;
4780 }
4782 size_t G1CollectedHeap::free_region_list_length() {
4783 assert(ZF_mon->owned_by_self(), "precondition.");
4784 size_t len = 0;
4785 HeapRegion* cur = _free_region_list;
4786 while (cur != NULL) {
4787 len++;
4788 cur = cur->next_from_free_list();
4789 }
4790 return len;
4791 }
4793 size_t G1CollectedHeap::unclean_region_list_length() {
4794 assert(ZF_mon->owned_by_self(), "precondition.");
4795 return _unclean_region_list.length();
4796 }
4798 size_t G1CollectedHeap::n_regions() {
4799 return _hrs->length();
4800 }
4802 size_t G1CollectedHeap::max_regions() {
4803 return
4804 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4805 HeapRegion::GrainBytes;
4806 }
4808 size_t G1CollectedHeap::free_regions() {
4809 /* Possibly-expensive assert.
4810 assert(_free_regions == count_free_regions(),
4811 "_free_regions is off.");
4812 */
4813 return _free_regions;
4814 }
4816 bool G1CollectedHeap::should_zf() {
4817 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4818 }
4820 class RegionCounter: public HeapRegionClosure {
4821 size_t _n;
4822 public:
4823 RegionCounter() : _n(0) {}
4824 bool doHeapRegion(HeapRegion* r) {
4825 if (r->is_empty()) {
4826 assert(!r->isHumongous(), "H regions should not be empty.");
4827 _n++;
4828 }
4829 return false;
4830 }
4831 int res() { return (int) _n; }
4832 };
4834 size_t G1CollectedHeap::count_free_regions() {
4835 RegionCounter rc;
4836 heap_region_iterate(&rc);
4837 size_t n = rc.res();
4838 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4839 n--;
4840 return n;
4841 }
4843 size_t G1CollectedHeap::count_free_regions_list() {
4844 size_t n = 0;
4845 size_t o = 0;
4846 ZF_mon->lock_without_safepoint_check();
4847 HeapRegion* cur = _free_region_list;
4848 while (cur != NULL) {
4849 cur = cur->next_from_free_list();
4850 n++;
4851 }
4852 size_t m = unclean_region_list_length();
4853 ZF_mon->unlock();
4854 return n + m;
4855 }
4857 bool G1CollectedHeap::should_set_young_locked() {
4858 assert(heap_lock_held_for_gc(),
4859 "the heap lock should already be held by or for this thread");
4860 return (g1_policy()->in_young_gc_mode() &&
4861 g1_policy()->should_add_next_region_to_young_list());
4862 }
4864 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4865 assert(heap_lock_held_for_gc(),
4866 "the heap lock should already be held by or for this thread");
4867 _young_list->push_region(hr);
4868 g1_policy()->set_region_short_lived(hr);
4869 }
4871 class NoYoungRegionsClosure: public HeapRegionClosure {
4872 private:
4873 bool _success;
4874 public:
4875 NoYoungRegionsClosure() : _success(true) { }
4876 bool doHeapRegion(HeapRegion* r) {
4877 if (r->is_young()) {
4878 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
4879 r->bottom(), r->end());
4880 _success = false;
4881 }
4882 return false;
4883 }
4884 bool success() { return _success; }
4885 };
4887 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
4888 bool check_sample) {
4889 bool ret = true;
4891 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
4892 if (!ignore_scan_only_list) {
4893 NoYoungRegionsClosure closure;
4894 heap_region_iterate(&closure);
4895 ret = ret && closure.success();
4896 }
4898 return ret;
4899 }
4901 void G1CollectedHeap::empty_young_list() {
4902 assert(heap_lock_held_for_gc(),
4903 "the heap lock should already be held by or for this thread");
4904 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
4906 _young_list->empty_list();
4907 }
4909 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
4910 bool no_allocs = true;
4911 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
4912 HeapRegion* r = _gc_alloc_regions[ap];
4913 no_allocs = r == NULL || r->saved_mark_at_top();
4914 }
4915 return no_allocs;
4916 }
4918 void G1CollectedHeap::retire_all_alloc_regions() {
4919 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4920 HeapRegion* r = _gc_alloc_regions[ap];
4921 if (r != NULL) {
4922 // Check for aliases.
4923 bool has_processed_alias = false;
4924 for (int i = 0; i < ap; ++i) {
4925 if (_gc_alloc_regions[i] == r) {
4926 has_processed_alias = true;
4927 break;
4928 }
4929 }
4930 if (!has_processed_alias) {
4931 retire_alloc_region(r, false /* par */);
4932 }
4933 }
4934 }
4935 }
4938 // Done at the start of full GC.
4939 void G1CollectedHeap::tear_down_region_lists() {
4940 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4941 while (pop_unclean_region_list_locked() != NULL) ;
4942 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
4943 "Postconditions of loop.")
4944 while (pop_free_region_list_locked() != NULL) ;
4945 assert(_free_region_list == NULL, "Postcondition of loop.");
4946 if (_free_region_list_size != 0) {
4947 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
4948 print_on(gclog_or_tty, true /* extended */);
4949 }
4950 assert(_free_region_list_size == 0, "Postconditions of loop.");
4951 }
4954 class RegionResetter: public HeapRegionClosure {
4955 G1CollectedHeap* _g1;
4956 int _n;
4957 public:
4958 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4959 bool doHeapRegion(HeapRegion* r) {
4960 if (r->continuesHumongous()) return false;
4961 if (r->top() > r->bottom()) {
4962 if (r->top() < r->end()) {
4963 Copy::fill_to_words(r->top(),
4964 pointer_delta(r->end(), r->top()));
4965 }
4966 r->set_zero_fill_allocated();
4967 } else {
4968 assert(r->is_empty(), "tautology");
4969 _n++;
4970 switch (r->zero_fill_state()) {
4971 case HeapRegion::NotZeroFilled:
4972 case HeapRegion::ZeroFilling:
4973 _g1->put_region_on_unclean_list_locked(r);
4974 break;
4975 case HeapRegion::Allocated:
4976 r->set_zero_fill_complete();
4977 // no break; go on to put on free list.
4978 case HeapRegion::ZeroFilled:
4979 _g1->put_free_region_on_list_locked(r);
4980 break;
4981 }
4982 }
4983 return false;
4984 }
4986 int getFreeRegionCount() {return _n;}
4987 };
4989 // Done at the end of full GC.
4990 void G1CollectedHeap::rebuild_region_lists() {
4991 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4992 // This needs to go at the end of the full GC.
4993 RegionResetter rs;
4994 heap_region_iterate(&rs);
4995 _free_regions = rs.getFreeRegionCount();
4996 // Tell the ZF thread it may have work to do.
4997 if (should_zf()) ZF_mon->notify_all();
4998 }
5000 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5001 G1CollectedHeap* _g1;
5002 int _n;
5003 public:
5004 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5005 bool doHeapRegion(HeapRegion* r) {
5006 if (r->continuesHumongous()) return false;
5007 if (r->top() > r->bottom()) {
5008 // There are assertions in "set_zero_fill_needed()" below that
5009 // require top() == bottom(), so this is technically illegal.
5010 // We'll skirt the law here, by making that true temporarily.
5011 DEBUG_ONLY(HeapWord* save_top = r->top();
5012 r->set_top(r->bottom()));
5013 r->set_zero_fill_needed();
5014 DEBUG_ONLY(r->set_top(save_top));
5015 }
5016 return false;
5017 }
5018 };
5020 // Done at the start of full GC.
5021 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5022 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5023 // This needs to go at the end of the full GC.
5024 UsedRegionsNeedZeroFillSetter rs;
5025 heap_region_iterate(&rs);
5026 }
5028 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5029 _refine_cte_cl->set_concurrent(concurrent);
5030 }
5032 #ifndef PRODUCT
5034 class PrintHeapRegionClosure: public HeapRegionClosure {
5035 public:
5036 bool doHeapRegion(HeapRegion *r) {
5037 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5038 if (r != NULL) {
5039 if (r->is_on_free_list())
5040 gclog_or_tty->print("Free ");
5041 if (r->is_young())
5042 gclog_or_tty->print("Young ");
5043 if (r->isHumongous())
5044 gclog_or_tty->print("Is Humongous ");
5045 r->print();
5046 }
5047 return false;
5048 }
5049 };
5051 class SortHeapRegionClosure : public HeapRegionClosure {
5052 size_t young_regions,free_regions, unclean_regions;
5053 size_t hum_regions, count;
5054 size_t unaccounted, cur_unclean, cur_alloc;
5055 size_t total_free;
5056 HeapRegion* cur;
5057 public:
5058 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5059 free_regions(0), unclean_regions(0),
5060 hum_regions(0),
5061 count(0), unaccounted(0),
5062 cur_alloc(0), total_free(0)
5063 {}
5064 bool doHeapRegion(HeapRegion *r) {
5065 count++;
5066 if (r->is_on_free_list()) free_regions++;
5067 else if (r->is_on_unclean_list()) unclean_regions++;
5068 else if (r->isHumongous()) hum_regions++;
5069 else if (r->is_young()) young_regions++;
5070 else if (r == cur) cur_alloc++;
5071 else unaccounted++;
5072 return false;
5073 }
5074 void print() {
5075 total_free = free_regions + unclean_regions;
5076 gclog_or_tty->print("%d regions\n", count);
5077 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5078 total_free, free_regions, unclean_regions);
5079 gclog_or_tty->print("%d humongous %d young\n",
5080 hum_regions, young_regions);
5081 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5082 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5083 }
5084 };
5086 void G1CollectedHeap::print_region_counts() {
5087 SortHeapRegionClosure sc(_cur_alloc_region);
5088 PrintHeapRegionClosure cl;
5089 heap_region_iterate(&cl);
5090 heap_region_iterate(&sc);
5091 sc.print();
5092 print_region_accounting_info();
5093 };
5095 bool G1CollectedHeap::regions_accounted_for() {
5096 // TODO: regions accounting for young/survivor/tenured
5097 return true;
5098 }
5100 bool G1CollectedHeap::print_region_accounting_info() {
5101 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5102 free_regions(),
5103 count_free_regions(), count_free_regions_list(),
5104 _free_region_list_size, _unclean_region_list.sz());
5105 gclog_or_tty->print_cr("cur_alloc: %d.",
5106 (_cur_alloc_region == NULL ? 0 : 1));
5107 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5109 // TODO: check regions accounting for young/survivor/tenured
5110 return true;
5111 }
5113 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5114 HeapRegion* hr = heap_region_containing(p);
5115 if (hr == NULL) {
5116 return is_in_permanent(p);
5117 } else {
5118 return hr->is_in(p);
5119 }
5120 }
5121 #endif // !PRODUCT
5123 void G1CollectedHeap::g1_unimplemented() {
5124 // Unimplemented();
5125 }