Thu, 30 Jul 2009 16:22:58 -0400
6819085: G1: use larger and/or user settable region size
Summary: Instead of the region size being hard-coded, allow the user to set it.
Reviewed-by: jmasa, johnc, 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 public:
2214 // use_prev_marking == true -> use "prev" marking information,
2215 // use_prev_marking == false -> use "next" marking information
2216 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2217 : _allow_dirty(allow_dirty),
2218 _par(par),
2219 _use_prev_marking(use_prev_marking) {}
2221 bool doHeapRegion(HeapRegion* r) {
2222 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2223 "Should be unclaimed at verify points.");
2224 if (!r->continuesHumongous()) {
2225 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2226 r->verify(_allow_dirty, _use_prev_marking);
2227 r->object_iterate(¬_dead_yet_cl);
2228 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2229 "More live objects than counted in last complete marking.");
2230 }
2231 return false;
2232 }
2233 };
2235 class VerifyRootsClosure: public OopsInGenClosure {
2236 private:
2237 G1CollectedHeap* _g1h;
2238 bool _failures;
2239 bool _use_prev_marking;
2240 public:
2241 // use_prev_marking == true -> use "prev" marking information,
2242 // use_prev_marking == false -> use "next" marking information
2243 VerifyRootsClosure(bool use_prev_marking) :
2244 _g1h(G1CollectedHeap::heap()),
2245 _failures(false),
2246 _use_prev_marking(use_prev_marking) { }
2248 bool failures() { return _failures; }
2250 template <class T> void do_oop_nv(T* p) {
2251 T heap_oop = oopDesc::load_heap_oop(p);
2252 if (!oopDesc::is_null(heap_oop)) {
2253 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2254 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2255 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2256 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2257 obj->print_on(gclog_or_tty);
2258 _failures = true;
2259 }
2260 }
2261 }
2263 void do_oop(oop* p) { do_oop_nv(p); }
2264 void do_oop(narrowOop* p) { do_oop_nv(p); }
2265 };
2267 // This is the task used for parallel heap verification.
2269 class G1ParVerifyTask: public AbstractGangTask {
2270 private:
2271 G1CollectedHeap* _g1h;
2272 bool _allow_dirty;
2273 bool _use_prev_marking;
2275 public:
2276 // use_prev_marking == true -> use "prev" marking information,
2277 // use_prev_marking == false -> use "next" marking information
2278 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2279 bool use_prev_marking) :
2280 AbstractGangTask("Parallel verify task"),
2281 _g1h(g1h),
2282 _allow_dirty(allow_dirty),
2283 _use_prev_marking(use_prev_marking) { }
2285 void work(int worker_i) {
2286 HandleMark hm;
2287 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2288 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2289 HeapRegion::ParVerifyClaimValue);
2290 }
2291 };
2293 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2294 verify(allow_dirty, silent, /* use_prev_marking */ true);
2295 }
2297 void G1CollectedHeap::verify(bool allow_dirty,
2298 bool silent,
2299 bool use_prev_marking) {
2300 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2301 if (!silent) { gclog_or_tty->print("roots "); }
2302 VerifyRootsClosure rootsCl(use_prev_marking);
2303 process_strong_roots(false,
2304 SharedHeap::SO_AllClasses,
2305 &rootsCl,
2306 &rootsCl);
2307 rem_set()->invalidate(perm_gen()->used_region(), false);
2308 if (!silent) { gclog_or_tty->print("heapRegions "); }
2309 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2310 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2311 "sanity check");
2313 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2314 int n_workers = workers()->total_workers();
2315 set_par_threads(n_workers);
2316 workers()->run_task(&task);
2317 set_par_threads(0);
2319 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2320 "sanity check");
2322 reset_heap_region_claim_values();
2324 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2325 "sanity check");
2326 } else {
2327 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2328 _hrs->iterate(&blk);
2329 }
2330 if (!silent) gclog_or_tty->print("remset ");
2331 rem_set()->verify();
2332 guarantee(!rootsCl.failures(), "should not have had failures");
2333 } else {
2334 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2335 }
2336 }
2338 class PrintRegionClosure: public HeapRegionClosure {
2339 outputStream* _st;
2340 public:
2341 PrintRegionClosure(outputStream* st) : _st(st) {}
2342 bool doHeapRegion(HeapRegion* r) {
2343 r->print_on(_st);
2344 return false;
2345 }
2346 };
2348 void G1CollectedHeap::print() const { print_on(tty); }
2350 void G1CollectedHeap::print_on(outputStream* st) const {
2351 print_on(st, PrintHeapAtGCExtended);
2352 }
2354 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2355 st->print(" %-20s", "garbage-first heap");
2356 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2357 capacity()/K, used_unlocked()/K);
2358 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2359 _g1_storage.low_boundary(),
2360 _g1_storage.high(),
2361 _g1_storage.high_boundary());
2362 st->cr();
2363 st->print(" region size " SIZE_FORMAT "K, ",
2364 HeapRegion::GrainBytes/K);
2365 size_t young_regions = _young_list->length();
2366 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2367 young_regions, young_regions * HeapRegion::GrainBytes / K);
2368 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2369 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2370 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2371 st->cr();
2372 perm()->as_gen()->print_on(st);
2373 if (extended) {
2374 print_on_extended(st);
2375 }
2376 }
2378 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2379 PrintRegionClosure blk(st);
2380 _hrs->iterate(&blk);
2381 }
2383 class PrintOnThreadsClosure : public ThreadClosure {
2384 outputStream* _st;
2385 public:
2386 PrintOnThreadsClosure(outputStream* st) : _st(st) { }
2387 virtual void do_thread(Thread *t) {
2388 t->print_on(_st);
2389 }
2390 };
2392 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2393 if (ParallelGCThreads > 0) {
2394 workers()->print_worker_threads();
2395 }
2396 st->print("\"G1 concurrent mark GC Thread\" ");
2397 _cmThread->print();
2398 st->cr();
2399 st->print("\"G1 concurrent refinement GC Threads\" ");
2400 PrintOnThreadsClosure p(st);
2401 _cg1r->threads_do(&p);
2402 st->cr();
2403 st->print("\"G1 zero-fill GC Thread\" ");
2404 _czft->print_on(st);
2405 st->cr();
2406 }
2408 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2409 if (ParallelGCThreads > 0) {
2410 workers()->threads_do(tc);
2411 }
2412 tc->do_thread(_cmThread);
2413 _cg1r->threads_do(tc);
2414 tc->do_thread(_czft);
2415 }
2417 void G1CollectedHeap::print_tracing_info() const {
2418 // We'll overload this to mean "trace GC pause statistics."
2419 if (TraceGen0Time || TraceGen1Time) {
2420 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2421 // to that.
2422 g1_policy()->print_tracing_info();
2423 }
2424 if (G1SummarizeRSetStats) {
2425 g1_rem_set()->print_summary_info();
2426 }
2427 if (G1SummarizeConcurrentMark) {
2428 concurrent_mark()->print_summary_info();
2429 }
2430 if (G1SummarizeZFStats) {
2431 ConcurrentZFThread::print_summary_info();
2432 }
2433 g1_policy()->print_yg_surv_rate_info();
2435 SpecializationStats::print();
2436 }
2439 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2440 HeapRegion* hr = heap_region_containing(addr);
2441 if (hr == NULL) {
2442 return 0;
2443 } else {
2444 return 1;
2445 }
2446 }
2448 G1CollectedHeap* G1CollectedHeap::heap() {
2449 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2450 "not a garbage-first heap");
2451 return _g1h;
2452 }
2454 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2455 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2456 // Call allocation profiler
2457 AllocationProfiler::iterate_since_last_gc();
2458 // Fill TLAB's and such
2459 ensure_parsability(true);
2460 }
2462 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2463 // FIXME: what is this about?
2464 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2465 // is set.
2466 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2467 "derived pointer present"));
2468 }
2470 void G1CollectedHeap::do_collection_pause() {
2471 // Read the GC count while holding the Heap_lock
2472 // we need to do this _before_ wait_for_cleanup_complete(), to
2473 // ensure that we do not give up the heap lock and potentially
2474 // pick up the wrong count
2475 int gc_count_before = SharedHeap::heap()->total_collections();
2477 // Don't want to do a GC pause while cleanup is being completed!
2478 wait_for_cleanup_complete();
2480 g1_policy()->record_stop_world_start();
2481 {
2482 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2483 VM_G1IncCollectionPause op(gc_count_before);
2484 VMThread::execute(&op);
2485 }
2486 }
2488 void
2489 G1CollectedHeap::doConcurrentMark() {
2490 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2491 if (!_cmThread->in_progress()) {
2492 _cmThread->set_started();
2493 CGC_lock->notify();
2494 }
2495 }
2497 class VerifyMarkedObjsClosure: public ObjectClosure {
2498 G1CollectedHeap* _g1h;
2499 public:
2500 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2501 void do_object(oop obj) {
2502 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2503 "markandsweep mark should agree with concurrent deadness");
2504 }
2505 };
2507 void
2508 G1CollectedHeap::checkConcurrentMark() {
2509 VerifyMarkedObjsClosure verifycl(this);
2510 // MutexLockerEx x(getMarkBitMapLock(),
2511 // Mutex::_no_safepoint_check_flag);
2512 object_iterate(&verifycl, false);
2513 }
2515 void G1CollectedHeap::do_sync_mark() {
2516 _cm->checkpointRootsInitial();
2517 _cm->markFromRoots();
2518 _cm->checkpointRootsFinal(false);
2519 }
2521 // <NEW PREDICTION>
2523 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2524 bool young) {
2525 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2526 }
2528 void G1CollectedHeap::check_if_region_is_too_expensive(double
2529 predicted_time_ms) {
2530 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2531 }
2533 size_t G1CollectedHeap::pending_card_num() {
2534 size_t extra_cards = 0;
2535 JavaThread *curr = Threads::first();
2536 while (curr != NULL) {
2537 DirtyCardQueue& dcq = curr->dirty_card_queue();
2538 extra_cards += dcq.size();
2539 curr = curr->next();
2540 }
2541 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2542 size_t buffer_size = dcqs.buffer_size();
2543 size_t buffer_num = dcqs.completed_buffers_num();
2544 return buffer_size * buffer_num + extra_cards;
2545 }
2547 size_t G1CollectedHeap::max_pending_card_num() {
2548 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2549 size_t buffer_size = dcqs.buffer_size();
2550 size_t buffer_num = dcqs.completed_buffers_num();
2551 int thread_num = Threads::number_of_threads();
2552 return (buffer_num + thread_num) * buffer_size;
2553 }
2555 size_t G1CollectedHeap::cards_scanned() {
2556 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2557 return g1_rset->cardsScanned();
2558 }
2560 void
2561 G1CollectedHeap::setup_surviving_young_words() {
2562 guarantee( _surviving_young_words == NULL, "pre-condition" );
2563 size_t array_length = g1_policy()->young_cset_length();
2564 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2565 if (_surviving_young_words == NULL) {
2566 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2567 "Not enough space for young surv words summary.");
2568 }
2569 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2570 #ifdef ASSERT
2571 for (size_t i = 0; i < array_length; ++i) {
2572 assert( _surviving_young_words[i] == 0, "memset above" );
2573 }
2574 #endif // !ASSERT
2575 }
2577 void
2578 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2579 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2580 size_t array_length = g1_policy()->young_cset_length();
2581 for (size_t i = 0; i < array_length; ++i)
2582 _surviving_young_words[i] += surv_young_words[i];
2583 }
2585 void
2586 G1CollectedHeap::cleanup_surviving_young_words() {
2587 guarantee( _surviving_young_words != NULL, "pre-condition" );
2588 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2589 _surviving_young_words = NULL;
2590 }
2592 // </NEW PREDICTION>
2594 void
2595 G1CollectedHeap::do_collection_pause_at_safepoint() {
2596 if (PrintHeapAtGC) {
2597 Universe::print_heap_before_gc();
2598 }
2600 {
2601 char verbose_str[128];
2602 sprintf(verbose_str, "GC pause ");
2603 if (g1_policy()->in_young_gc_mode()) {
2604 if (g1_policy()->full_young_gcs())
2605 strcat(verbose_str, "(young)");
2606 else
2607 strcat(verbose_str, "(partial)");
2608 }
2609 if (g1_policy()->should_initiate_conc_mark())
2610 strcat(verbose_str, " (initial-mark)");
2612 GCCauseSetter x(this, GCCause::_g1_inc_collection_pause);
2614 // if PrintGCDetails is on, we'll print long statistics information
2615 // in the collector policy code, so let's not print this as the output
2616 // is messy if we do.
2617 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2618 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2619 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2621 ResourceMark rm;
2622 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2623 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2624 guarantee(!is_gc_active(), "collection is not reentrant");
2625 assert(regions_accounted_for(), "Region leakage!");
2627 increment_gc_time_stamp();
2629 if (g1_policy()->in_young_gc_mode()) {
2630 assert(check_young_list_well_formed(),
2631 "young list should be well formed");
2632 }
2634 if (GC_locker::is_active()) {
2635 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2636 }
2638 bool abandoned = false;
2639 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2640 IsGCActiveMark x;
2642 gc_prologue(false);
2643 increment_total_collections(false /* full gc */);
2645 #if G1_REM_SET_LOGGING
2646 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2647 print();
2648 #endif
2650 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2651 HandleMark hm; // Discard invalid handles created during verification
2652 prepare_for_verify();
2653 gclog_or_tty->print(" VerifyBeforeGC:");
2654 Universe::verify(false);
2655 }
2657 COMPILER2_PRESENT(DerivedPointerTable::clear());
2659 // We want to turn off ref discovery, if necessary, and turn it back on
2660 // on again later if we do. XXX Dubious: why is discovery disabled?
2661 bool was_enabled = ref_processor()->discovery_enabled();
2662 if (was_enabled) ref_processor()->disable_discovery();
2664 // Forget the current alloc region (we might even choose it to be part
2665 // of the collection set!).
2666 abandon_cur_alloc_region();
2668 // The elapsed time induced by the start time below deliberately elides
2669 // the possible verification above.
2670 double start_time_sec = os::elapsedTime();
2671 size_t start_used_bytes = used();
2673 g1_policy()->record_collection_pause_start(start_time_sec,
2674 start_used_bytes);
2676 guarantee(_in_cset_fast_test == NULL, "invariant");
2677 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2678 _in_cset_fast_test_length = max_regions();
2679 _in_cset_fast_test_base =
2680 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2681 memset(_in_cset_fast_test_base, false,
2682 _in_cset_fast_test_length * sizeof(bool));
2683 // We're biasing _in_cset_fast_test to avoid subtracting the
2684 // beginning of the heap every time we want to index; basically
2685 // it's the same with what we do with the card table.
2686 _in_cset_fast_test = _in_cset_fast_test_base -
2687 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2689 #if SCAN_ONLY_VERBOSE
2690 _young_list->print();
2691 #endif // SCAN_ONLY_VERBOSE
2693 if (g1_policy()->should_initiate_conc_mark()) {
2694 concurrent_mark()->checkpointRootsInitialPre();
2695 }
2696 save_marks();
2698 // We must do this before any possible evacuation that should propagate
2699 // marks.
2700 if (mark_in_progress()) {
2701 double start_time_sec = os::elapsedTime();
2703 _cm->drainAllSATBBuffers();
2704 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2705 g1_policy()->record_satb_drain_time(finish_mark_ms);
2706 }
2707 // Record the number of elements currently on the mark stack, so we
2708 // only iterate over these. (Since evacuation may add to the mark
2709 // stack, doing more exposes race conditions.) If no mark is in
2710 // progress, this will be zero.
2711 _cm->set_oops_do_bound();
2713 assert(regions_accounted_for(), "Region leakage.");
2715 if (mark_in_progress())
2716 concurrent_mark()->newCSet();
2718 // Now choose the CS.
2719 g1_policy()->choose_collection_set();
2721 // We may abandon a pause if we find no region that will fit in the MMU
2722 // pause.
2723 bool abandoned = (g1_policy()->collection_set() == NULL);
2725 // Nothing to do if we were unable to choose a collection set.
2726 if (!abandoned) {
2727 #if G1_REM_SET_LOGGING
2728 gclog_or_tty->print_cr("\nAfter pause, heap:");
2729 print();
2730 #endif
2732 setup_surviving_young_words();
2734 // Set up the gc allocation regions.
2735 get_gc_alloc_regions();
2737 // Actually do the work...
2738 evacuate_collection_set();
2739 free_collection_set(g1_policy()->collection_set());
2740 g1_policy()->clear_collection_set();
2742 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2743 // this is more for peace of mind; we're nulling them here and
2744 // we're expecting them to be null at the beginning of the next GC
2745 _in_cset_fast_test = NULL;
2746 _in_cset_fast_test_base = NULL;
2748 cleanup_surviving_young_words();
2750 if (g1_policy()->in_young_gc_mode()) {
2751 _young_list->reset_sampled_info();
2752 assert(check_young_list_empty(true),
2753 "young list should be empty");
2755 #if SCAN_ONLY_VERBOSE
2756 _young_list->print();
2757 #endif // SCAN_ONLY_VERBOSE
2759 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2760 _young_list->first_survivor_region(),
2761 _young_list->last_survivor_region());
2762 _young_list->reset_auxilary_lists();
2763 }
2764 } else {
2765 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2766 }
2768 if (evacuation_failed()) {
2769 _summary_bytes_used = recalculate_used();
2770 } else {
2771 // The "used" of the the collection set have already been subtracted
2772 // when they were freed. Add in the bytes evacuated.
2773 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2774 }
2776 if (g1_policy()->in_young_gc_mode() &&
2777 g1_policy()->should_initiate_conc_mark()) {
2778 concurrent_mark()->checkpointRootsInitialPost();
2779 set_marking_started();
2780 // CAUTION: after the doConcurrentMark() call below,
2781 // the concurrent marking thread(s) could be running
2782 // concurrently with us. Make sure that anything after
2783 // this point does not assume that we are the only GC thread
2784 // running. Note: of course, the actual marking work will
2785 // not start until the safepoint itself is released in
2786 // ConcurrentGCThread::safepoint_desynchronize().
2787 doConcurrentMark();
2788 }
2790 #if SCAN_ONLY_VERBOSE
2791 _young_list->print();
2792 #endif // SCAN_ONLY_VERBOSE
2794 double end_time_sec = os::elapsedTime();
2795 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2796 g1_policy()->record_pause_time_ms(pause_time_ms);
2797 g1_policy()->record_collection_pause_end(abandoned);
2799 assert(regions_accounted_for(), "Region leakage.");
2801 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2802 HandleMark hm; // Discard invalid handles created during verification
2803 gclog_or_tty->print(" VerifyAfterGC:");
2804 prepare_for_verify();
2805 Universe::verify(false);
2806 }
2808 if (was_enabled) ref_processor()->enable_discovery();
2810 {
2811 size_t expand_bytes = g1_policy()->expansion_amount();
2812 if (expand_bytes > 0) {
2813 size_t bytes_before = capacity();
2814 expand(expand_bytes);
2815 }
2816 }
2818 if (mark_in_progress()) {
2819 concurrent_mark()->update_g1_committed();
2820 }
2822 #ifdef TRACESPINNING
2823 ParallelTaskTerminator::print_termination_counts();
2824 #endif
2826 gc_epilogue(false);
2827 }
2829 assert(verify_region_lists(), "Bad region lists.");
2831 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2832 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2833 print_tracing_info();
2834 vm_exit(-1);
2835 }
2836 }
2838 if (PrintHeapAtGC) {
2839 Universe::print_heap_after_gc();
2840 }
2841 if (G1SummarizeRSetStats &&
2842 (G1SummarizeRSetStatsPeriod > 0) &&
2843 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
2844 g1_rem_set()->print_summary_info();
2845 }
2846 }
2848 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2849 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2850 // make sure we don't call set_gc_alloc_region() multiple times on
2851 // the same region
2852 assert(r == NULL || !r->is_gc_alloc_region(),
2853 "shouldn't already be a GC alloc region");
2854 HeapWord* original_top = NULL;
2855 if (r != NULL)
2856 original_top = r->top();
2858 // We will want to record the used space in r as being there before gc.
2859 // One we install it as a GC alloc region it's eligible for allocation.
2860 // So record it now and use it later.
2861 size_t r_used = 0;
2862 if (r != NULL) {
2863 r_used = r->used();
2865 if (ParallelGCThreads > 0) {
2866 // need to take the lock to guard against two threads calling
2867 // get_gc_alloc_region concurrently (very unlikely but...)
2868 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2869 r->save_marks();
2870 }
2871 }
2872 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2873 _gc_alloc_regions[purpose] = r;
2874 if (old_alloc_region != NULL) {
2875 // Replace aliases too.
2876 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2877 if (_gc_alloc_regions[ap] == old_alloc_region) {
2878 _gc_alloc_regions[ap] = r;
2879 }
2880 }
2881 }
2882 if (r != NULL) {
2883 push_gc_alloc_region(r);
2884 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2885 // We are using a region as a GC alloc region after it has been used
2886 // as a mutator allocation region during the current marking cycle.
2887 // The mutator-allocated objects are currently implicitly marked, but
2888 // when we move hr->next_top_at_mark_start() forward at the the end
2889 // of the GC pause, they won't be. We therefore mark all objects in
2890 // the "gap". We do this object-by-object, since marking densely
2891 // does not currently work right with marking bitmap iteration. This
2892 // means we rely on TLAB filling at the start of pauses, and no
2893 // "resuscitation" of filled TLAB's. If we want to do this, we need
2894 // to fix the marking bitmap iteration.
2895 HeapWord* curhw = r->next_top_at_mark_start();
2896 HeapWord* t = original_top;
2898 while (curhw < t) {
2899 oop cur = (oop)curhw;
2900 // We'll assume parallel for generality. This is rare code.
2901 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2902 curhw = curhw + cur->size();
2903 }
2904 assert(curhw == t, "Should have parsed correctly.");
2905 }
2906 if (G1PolicyVerbose > 1) {
2907 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2908 "for survivors:", r->bottom(), original_top, r->end());
2909 r->print();
2910 }
2911 g1_policy()->record_before_bytes(r_used);
2912 }
2913 }
2915 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2916 assert(Thread::current()->is_VM_thread() ||
2917 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2918 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2919 "Precondition.");
2920 hr->set_is_gc_alloc_region(true);
2921 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2922 _gc_alloc_region_list = hr;
2923 }
2925 #ifdef G1_DEBUG
2926 class FindGCAllocRegion: public HeapRegionClosure {
2927 public:
2928 bool doHeapRegion(HeapRegion* r) {
2929 if (r->is_gc_alloc_region()) {
2930 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2931 r->hrs_index(), r->bottom());
2932 }
2933 return false;
2934 }
2935 };
2936 #endif // G1_DEBUG
2938 void G1CollectedHeap::forget_alloc_region_list() {
2939 assert(Thread::current()->is_VM_thread(), "Precondition");
2940 while (_gc_alloc_region_list != NULL) {
2941 HeapRegion* r = _gc_alloc_region_list;
2942 assert(r->is_gc_alloc_region(), "Invariant.");
2943 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
2944 // newly allocated data in order to be able to apply deferred updates
2945 // before the GC is done for verification purposes (i.e to allow
2946 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
2947 // collection.
2948 r->ContiguousSpace::set_saved_mark();
2949 _gc_alloc_region_list = r->next_gc_alloc_region();
2950 r->set_next_gc_alloc_region(NULL);
2951 r->set_is_gc_alloc_region(false);
2952 if (r->is_survivor()) {
2953 if (r->is_empty()) {
2954 r->set_not_young();
2955 } else {
2956 _young_list->add_survivor_region(r);
2957 }
2958 }
2959 if (r->is_empty()) {
2960 ++_free_regions;
2961 }
2962 }
2963 #ifdef G1_DEBUG
2964 FindGCAllocRegion fa;
2965 heap_region_iterate(&fa);
2966 #endif // G1_DEBUG
2967 }
2970 bool G1CollectedHeap::check_gc_alloc_regions() {
2971 // TODO: allocation regions check
2972 return true;
2973 }
2975 void G1CollectedHeap::get_gc_alloc_regions() {
2976 // First, let's check that the GC alloc region list is empty (it should)
2977 assert(_gc_alloc_region_list == NULL, "invariant");
2979 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2980 assert(_gc_alloc_regions[ap] == NULL, "invariant");
2981 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
2983 // Create new GC alloc regions.
2984 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
2985 _retained_gc_alloc_regions[ap] = NULL;
2987 if (alloc_region != NULL) {
2988 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
2990 // let's make sure that the GC alloc region is not tagged as such
2991 // outside a GC operation
2992 assert(!alloc_region->is_gc_alloc_region(), "sanity");
2994 if (alloc_region->in_collection_set() ||
2995 alloc_region->top() == alloc_region->end() ||
2996 alloc_region->top() == alloc_region->bottom()) {
2997 // we will discard the current GC alloc region if it's in the
2998 // collection set (it can happen!), if it's already full (no
2999 // point in using it), or if it's empty (this means that it
3000 // was emptied during a cleanup and it should be on the free
3001 // list now).
3003 alloc_region = NULL;
3004 }
3005 }
3007 if (alloc_region == NULL) {
3008 // we will get a new GC alloc region
3009 alloc_region = newAllocRegionWithExpansion(ap, 0);
3010 } else {
3011 // the region was retained from the last collection
3012 ++_gc_alloc_region_counts[ap];
3013 }
3015 if (alloc_region != NULL) {
3016 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3017 set_gc_alloc_region(ap, alloc_region);
3018 }
3020 assert(_gc_alloc_regions[ap] == NULL ||
3021 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3022 "the GC alloc region should be tagged as such");
3023 assert(_gc_alloc_regions[ap] == NULL ||
3024 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3025 "the GC alloc region should be the same as the GC alloc list head");
3026 }
3027 // Set alternative regions for allocation purposes that have reached
3028 // their limit.
3029 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3030 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3031 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3032 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3033 }
3034 }
3035 assert(check_gc_alloc_regions(), "alloc regions messed up");
3036 }
3038 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3039 // We keep a separate list of all regions that have been alloc regions in
3040 // the current collection pause. Forget that now. This method will
3041 // untag the GC alloc regions and tear down the GC alloc region
3042 // list. It's desirable that no regions are tagged as GC alloc
3043 // outside GCs.
3044 forget_alloc_region_list();
3046 // The current alloc regions contain objs that have survived
3047 // collection. Make them no longer GC alloc regions.
3048 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3049 HeapRegion* r = _gc_alloc_regions[ap];
3050 _retained_gc_alloc_regions[ap] = NULL;
3051 _gc_alloc_region_counts[ap] = 0;
3053 if (r != NULL) {
3054 // we retain nothing on _gc_alloc_regions between GCs
3055 set_gc_alloc_region(ap, NULL);
3057 if (r->is_empty()) {
3058 // we didn't actually allocate anything in it; let's just put
3059 // it on the free list
3060 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3061 r->set_zero_fill_complete();
3062 put_free_region_on_list_locked(r);
3063 } else if (_retain_gc_alloc_region[ap] && !totally) {
3064 // retain it so that we can use it at the beginning of the next GC
3065 _retained_gc_alloc_regions[ap] = r;
3066 }
3067 }
3068 }
3069 }
3071 #ifndef PRODUCT
3072 // Useful for debugging
3074 void G1CollectedHeap::print_gc_alloc_regions() {
3075 gclog_or_tty->print_cr("GC alloc regions");
3076 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3077 HeapRegion* r = _gc_alloc_regions[ap];
3078 if (r == NULL) {
3079 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3080 } else {
3081 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3082 ap, r->bottom(), r->used());
3083 }
3084 }
3085 }
3086 #endif // PRODUCT
3088 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3089 _drain_in_progress = false;
3090 set_evac_failure_closure(cl);
3091 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3092 }
3094 void G1CollectedHeap::finalize_for_evac_failure() {
3095 assert(_evac_failure_scan_stack != NULL &&
3096 _evac_failure_scan_stack->length() == 0,
3097 "Postcondition");
3098 assert(!_drain_in_progress, "Postcondition");
3099 // Don't have to delete, since the scan stack is a resource object.
3100 _evac_failure_scan_stack = NULL;
3101 }
3105 // *** Sequential G1 Evacuation
3107 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3108 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3109 // let the caller handle alloc failure
3110 if (alloc_region == NULL) return NULL;
3111 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3112 "Either the object is humongous or the region isn't");
3113 HeapWord* block = alloc_region->allocate(word_size);
3114 if (block == NULL) {
3115 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3116 }
3117 return block;
3118 }
3120 class G1IsAliveClosure: public BoolObjectClosure {
3121 G1CollectedHeap* _g1;
3122 public:
3123 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3124 void do_object(oop p) { assert(false, "Do not call."); }
3125 bool do_object_b(oop p) {
3126 // It is reachable if it is outside the collection set, or is inside
3127 // and forwarded.
3129 #ifdef G1_DEBUG
3130 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3131 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3132 !_g1->obj_in_cs(p) || p->is_forwarded());
3133 #endif // G1_DEBUG
3135 return !_g1->obj_in_cs(p) || p->is_forwarded();
3136 }
3137 };
3139 class G1KeepAliveClosure: public OopClosure {
3140 G1CollectedHeap* _g1;
3141 public:
3142 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3143 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3144 void do_oop( oop* p) {
3145 oop obj = *p;
3146 #ifdef G1_DEBUG
3147 if (PrintGC && Verbose) {
3148 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3149 p, (void*) obj, (void*) *p);
3150 }
3151 #endif // G1_DEBUG
3153 if (_g1->obj_in_cs(obj)) {
3154 assert( obj->is_forwarded(), "invariant" );
3155 *p = obj->forwardee();
3156 #ifdef G1_DEBUG
3157 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3158 (void*) obj, (void*) *p);
3159 #endif // G1_DEBUG
3160 }
3161 }
3162 };
3164 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3165 private:
3166 G1CollectedHeap* _g1;
3167 G1RemSet* _g1_rem_set;
3168 public:
3169 UpdateRSetImmediate(G1CollectedHeap* g1) :
3170 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3172 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3173 virtual void do_oop( oop* p) { do_oop_work(p); }
3174 template <class T> void do_oop_work(T* p) {
3175 assert(_from->is_in_reserved(p), "paranoia");
3176 T heap_oop = oopDesc::load_heap_oop(p);
3177 if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
3178 _g1_rem_set->par_write_ref(_from, p, 0);
3179 }
3180 }
3181 };
3183 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3184 private:
3185 G1CollectedHeap* _g1;
3186 DirtyCardQueue *_dcq;
3187 CardTableModRefBS* _ct_bs;
3189 public:
3190 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3191 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3193 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3194 virtual void do_oop( oop* p) { do_oop_work(p); }
3195 template <class T> void do_oop_work(T* p) {
3196 assert(_from->is_in_reserved(p), "paranoia");
3197 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3198 !_from->is_survivor()) {
3199 size_t card_index = _ct_bs->index_for(p);
3200 if (_ct_bs->mark_card_deferred(card_index)) {
3201 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3202 }
3203 }
3204 }
3205 };
3209 class RemoveSelfPointerClosure: public ObjectClosure {
3210 private:
3211 G1CollectedHeap* _g1;
3212 ConcurrentMark* _cm;
3213 HeapRegion* _hr;
3214 size_t _prev_marked_bytes;
3215 size_t _next_marked_bytes;
3216 OopsInHeapRegionClosure *_cl;
3217 public:
3218 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3219 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3220 _next_marked_bytes(0), _cl(cl) {}
3222 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3223 size_t next_marked_bytes() { return _next_marked_bytes; }
3225 // The original idea here was to coalesce evacuated and dead objects.
3226 // However that caused complications with the block offset table (BOT).
3227 // In particular if there were two TLABs, one of them partially refined.
3228 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3229 // The BOT entries of the unrefined part of TLAB_2 point to the start
3230 // of TLAB_2. If the last object of the TLAB_1 and the first object
3231 // of TLAB_2 are coalesced, then the cards of the unrefined part
3232 // would point into middle of the filler object.
3233 //
3234 // The current approach is to not coalesce and leave the BOT contents intact.
3235 void do_object(oop obj) {
3236 if (obj->is_forwarded() && obj->forwardee() == obj) {
3237 // The object failed to move.
3238 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3239 _cm->markPrev(obj);
3240 assert(_cm->isPrevMarked(obj), "Should be marked!");
3241 _prev_marked_bytes += (obj->size() * HeapWordSize);
3242 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3243 _cm->markAndGrayObjectIfNecessary(obj);
3244 }
3245 obj->set_mark(markOopDesc::prototype());
3246 // While we were processing RSet buffers during the
3247 // collection, we actually didn't scan any cards on the
3248 // collection set, since we didn't want to update remebered
3249 // sets with entries that point into the collection set, given
3250 // that live objects fromthe collection set are about to move
3251 // and such entries will be stale very soon. This change also
3252 // dealt with a reliability issue which involved scanning a
3253 // card in the collection set and coming across an array that
3254 // was being chunked and looking malformed. The problem is
3255 // that, if evacuation fails, we might have remembered set
3256 // entries missing given that we skipped cards on the
3257 // collection set. So, we'll recreate such entries now.
3258 obj->oop_iterate(_cl);
3259 assert(_cm->isPrevMarked(obj), "Should be marked!");
3260 } else {
3261 // The object has been either evacuated or is dead. Fill it with a
3262 // dummy object.
3263 MemRegion mr((HeapWord*)obj, obj->size());
3264 CollectedHeap::fill_with_object(mr);
3265 _cm->clearRangeBothMaps(mr);
3266 }
3267 }
3268 };
3270 void G1CollectedHeap::remove_self_forwarding_pointers() {
3271 UpdateRSetImmediate immediate_update(_g1h);
3272 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3273 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3274 OopsInHeapRegionClosure *cl;
3275 if (G1DeferredRSUpdate) {
3276 cl = &deferred_update;
3277 } else {
3278 cl = &immediate_update;
3279 }
3280 HeapRegion* cur = g1_policy()->collection_set();
3281 while (cur != NULL) {
3282 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3284 RemoveSelfPointerClosure rspc(_g1h, cl);
3285 if (cur->evacuation_failed()) {
3286 assert(cur->in_collection_set(), "bad CS");
3287 cl->set_region(cur);
3288 cur->object_iterate(&rspc);
3290 // A number of manipulations to make the TAMS be the current top,
3291 // and the marked bytes be the ones observed in the iteration.
3292 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3293 // The comments below are the postconditions achieved by the
3294 // calls. Note especially the last such condition, which says that
3295 // the count of marked bytes has been properly restored.
3296 cur->note_start_of_marking(false);
3297 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3298 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3299 // _next_marked_bytes == prev_marked_bytes.
3300 cur->note_end_of_marking();
3301 // _prev_top_at_mark_start == top(),
3302 // _prev_marked_bytes == prev_marked_bytes
3303 }
3304 // If there is no mark in progress, we modified the _next variables
3305 // above needlessly, but harmlessly.
3306 if (_g1h->mark_in_progress()) {
3307 cur->note_start_of_marking(false);
3308 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3309 // _next_marked_bytes == next_marked_bytes.
3310 }
3312 // Now make sure the region has the right index in the sorted array.
3313 g1_policy()->note_change_in_marked_bytes(cur);
3314 }
3315 cur = cur->next_in_collection_set();
3316 }
3317 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3319 // Now restore saved marks, if any.
3320 if (_objs_with_preserved_marks != NULL) {
3321 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3322 assert(_objs_with_preserved_marks->length() ==
3323 _preserved_marks_of_objs->length(), "Both or none.");
3324 guarantee(_objs_with_preserved_marks->length() ==
3325 _preserved_marks_of_objs->length(), "Both or none.");
3326 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3327 oop obj = _objs_with_preserved_marks->at(i);
3328 markOop m = _preserved_marks_of_objs->at(i);
3329 obj->set_mark(m);
3330 }
3331 // Delete the preserved marks growable arrays (allocated on the C heap).
3332 delete _objs_with_preserved_marks;
3333 delete _preserved_marks_of_objs;
3334 _objs_with_preserved_marks = NULL;
3335 _preserved_marks_of_objs = NULL;
3336 }
3337 }
3339 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3340 _evac_failure_scan_stack->push(obj);
3341 }
3343 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3344 assert(_evac_failure_scan_stack != NULL, "precondition");
3346 while (_evac_failure_scan_stack->length() > 0) {
3347 oop obj = _evac_failure_scan_stack->pop();
3348 _evac_failure_closure->set_region(heap_region_containing(obj));
3349 obj->oop_iterate_backwards(_evac_failure_closure);
3350 }
3351 }
3353 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3354 markOop m = old->mark();
3355 // forward to self
3356 assert(!old->is_forwarded(), "precondition");
3358 old->forward_to(old);
3359 handle_evacuation_failure_common(old, m);
3360 }
3362 oop
3363 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3364 oop old) {
3365 markOop m = old->mark();
3366 oop forward_ptr = old->forward_to_atomic(old);
3367 if (forward_ptr == NULL) {
3368 // Forward-to-self succeeded.
3369 if (_evac_failure_closure != cl) {
3370 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3371 assert(!_drain_in_progress,
3372 "Should only be true while someone holds the lock.");
3373 // Set the global evac-failure closure to the current thread's.
3374 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3375 set_evac_failure_closure(cl);
3376 // Now do the common part.
3377 handle_evacuation_failure_common(old, m);
3378 // Reset to NULL.
3379 set_evac_failure_closure(NULL);
3380 } else {
3381 // The lock is already held, and this is recursive.
3382 assert(_drain_in_progress, "This should only be the recursive case.");
3383 handle_evacuation_failure_common(old, m);
3384 }
3385 return old;
3386 } else {
3387 // Someone else had a place to copy it.
3388 return forward_ptr;
3389 }
3390 }
3392 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3393 set_evacuation_failed(true);
3395 preserve_mark_if_necessary(old, m);
3397 HeapRegion* r = heap_region_containing(old);
3398 if (!r->evacuation_failed()) {
3399 r->set_evacuation_failed(true);
3400 if (G1PrintRegions) {
3401 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3402 "["PTR_FORMAT","PTR_FORMAT")\n",
3403 r, r->bottom(), r->end());
3404 }
3405 }
3407 push_on_evac_failure_scan_stack(old);
3409 if (!_drain_in_progress) {
3410 // prevent recursion in copy_to_survivor_space()
3411 _drain_in_progress = true;
3412 drain_evac_failure_scan_stack();
3413 _drain_in_progress = false;
3414 }
3415 }
3417 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3418 if (m != markOopDesc::prototype()) {
3419 if (_objs_with_preserved_marks == NULL) {
3420 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3421 _objs_with_preserved_marks =
3422 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3423 _preserved_marks_of_objs =
3424 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3425 }
3426 _objs_with_preserved_marks->push(obj);
3427 _preserved_marks_of_objs->push(m);
3428 }
3429 }
3431 // *** Parallel G1 Evacuation
3433 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3434 size_t word_size) {
3435 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3436 // let the caller handle alloc failure
3437 if (alloc_region == NULL) return NULL;
3439 HeapWord* block = alloc_region->par_allocate(word_size);
3440 if (block == NULL) {
3441 MutexLockerEx x(par_alloc_during_gc_lock(),
3442 Mutex::_no_safepoint_check_flag);
3443 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3444 }
3445 return block;
3446 }
3448 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3449 bool par) {
3450 // Another thread might have obtained alloc_region for the given
3451 // purpose, and might be attempting to allocate in it, and might
3452 // succeed. Therefore, we can't do the "finalization" stuff on the
3453 // region below until we're sure the last allocation has happened.
3454 // We ensure this by allocating the remaining space with a garbage
3455 // object.
3456 if (par) par_allocate_remaining_space(alloc_region);
3457 // Now we can do the post-GC stuff on the region.
3458 alloc_region->note_end_of_copying();
3459 g1_policy()->record_after_bytes(alloc_region->used());
3460 }
3462 HeapWord*
3463 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3464 HeapRegion* alloc_region,
3465 bool par,
3466 size_t word_size) {
3467 HeapWord* block = NULL;
3468 // In the parallel case, a previous thread to obtain the lock may have
3469 // already assigned a new gc_alloc_region.
3470 if (alloc_region != _gc_alloc_regions[purpose]) {
3471 assert(par, "But should only happen in parallel case.");
3472 alloc_region = _gc_alloc_regions[purpose];
3473 if (alloc_region == NULL) return NULL;
3474 block = alloc_region->par_allocate(word_size);
3475 if (block != NULL) return block;
3476 // Otherwise, continue; this new region is empty, too.
3477 }
3478 assert(alloc_region != NULL, "We better have an allocation region");
3479 retire_alloc_region(alloc_region, par);
3481 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3482 // Cannot allocate more regions for the given purpose.
3483 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3484 // Is there an alternative?
3485 if (purpose != alt_purpose) {
3486 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3487 // Has not the alternative region been aliased?
3488 if (alloc_region != alt_region && alt_region != NULL) {
3489 // Try to allocate in the alternative region.
3490 if (par) {
3491 block = alt_region->par_allocate(word_size);
3492 } else {
3493 block = alt_region->allocate(word_size);
3494 }
3495 // Make an alias.
3496 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3497 if (block != NULL) {
3498 return block;
3499 }
3500 retire_alloc_region(alt_region, par);
3501 }
3502 // Both the allocation region and the alternative one are full
3503 // and aliased, replace them with a new allocation region.
3504 purpose = alt_purpose;
3505 } else {
3506 set_gc_alloc_region(purpose, NULL);
3507 return NULL;
3508 }
3509 }
3511 // Now allocate a new region for allocation.
3512 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3514 // let the caller handle alloc failure
3515 if (alloc_region != NULL) {
3517 assert(check_gc_alloc_regions(), "alloc regions messed up");
3518 assert(alloc_region->saved_mark_at_top(),
3519 "Mark should have been saved already.");
3520 // We used to assert that the region was zero-filled here, but no
3521 // longer.
3523 // This must be done last: once it's installed, other regions may
3524 // allocate in it (without holding the lock.)
3525 set_gc_alloc_region(purpose, alloc_region);
3527 if (par) {
3528 block = alloc_region->par_allocate(word_size);
3529 } else {
3530 block = alloc_region->allocate(word_size);
3531 }
3532 // Caller handles alloc failure.
3533 } else {
3534 // This sets other apis using the same old alloc region to NULL, also.
3535 set_gc_alloc_region(purpose, NULL);
3536 }
3537 return block; // May be NULL.
3538 }
3540 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3541 HeapWord* block = NULL;
3542 size_t free_words;
3543 do {
3544 free_words = r->free()/HeapWordSize;
3545 // If there's too little space, no one can allocate, so we're done.
3546 if (free_words < (size_t)oopDesc::header_size()) return;
3547 // Otherwise, try to claim it.
3548 block = r->par_allocate(free_words);
3549 } while (block == NULL);
3550 fill_with_object(block, free_words);
3551 }
3553 #ifndef PRODUCT
3554 bool GCLabBitMapClosure::do_bit(size_t offset) {
3555 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3556 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3557 return true;
3558 }
3559 #endif // PRODUCT
3561 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3562 : _g1h(g1h),
3563 _refs(g1h->task_queue(queue_num)),
3564 _dcq(&g1h->dirty_card_queue_set()),
3565 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3566 _g1_rem(g1h->g1_rem_set()),
3567 _hash_seed(17), _queue_num(queue_num),
3568 _term_attempts(0),
3569 _age_table(false),
3570 #if G1_DETAILED_STATS
3571 _pushes(0), _pops(0), _steals(0),
3572 _steal_attempts(0), _overflow_pushes(0),
3573 #endif
3574 _strong_roots_time(0), _term_time(0),
3575 _alloc_buffer_waste(0), _undo_waste(0)
3576 {
3577 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3578 // we "sacrifice" entry 0 to keep track of surviving bytes for
3579 // non-young regions (where the age is -1)
3580 // We also add a few elements at the beginning and at the end in
3581 // an attempt to eliminate cache contention
3582 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3583 size_t array_length = PADDING_ELEM_NUM +
3584 real_length +
3585 PADDING_ELEM_NUM;
3586 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3587 if (_surviving_young_words_base == NULL)
3588 vm_exit_out_of_memory(array_length * sizeof(size_t),
3589 "Not enough space for young surv histo.");
3590 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3591 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3593 _overflowed_refs = new OverflowQueue(10);
3595 _start = os::elapsedTime();
3596 }
3598 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3599 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3600 _par_scan_state(par_scan_state) { }
3602 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3603 // This is called _after_ do_oop_work has been called, hence after
3604 // the object has been relocated to its new location and *p points
3605 // to its new location.
3607 T heap_oop = oopDesc::load_heap_oop(p);
3608 if (!oopDesc::is_null(heap_oop)) {
3609 oop obj = oopDesc::decode_heap_oop(heap_oop);
3610 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3611 "shouldn't still be in the CSet if evacuation didn't fail.");
3612 HeapWord* addr = (HeapWord*)obj;
3613 if (_g1->is_in_g1_reserved(addr))
3614 _cm->grayRoot(oop(addr));
3615 }
3616 }
3618 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3619 size_t word_sz = old->size();
3620 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3621 // +1 to make the -1 indexes valid...
3622 int young_index = from_region->young_index_in_cset()+1;
3623 assert( (from_region->is_young() && young_index > 0) ||
3624 (!from_region->is_young() && young_index == 0), "invariant" );
3625 G1CollectorPolicy* g1p = _g1->g1_policy();
3626 markOop m = old->mark();
3627 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3628 : m->age();
3629 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3630 word_sz);
3631 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3632 oop obj = oop(obj_ptr);
3634 if (obj_ptr == NULL) {
3635 // This will either forward-to-self, or detect that someone else has
3636 // installed a forwarding pointer.
3637 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3638 return _g1->handle_evacuation_failure_par(cl, old);
3639 }
3641 // We're going to allocate linearly, so might as well prefetch ahead.
3642 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3644 oop forward_ptr = old->forward_to_atomic(obj);
3645 if (forward_ptr == NULL) {
3646 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3647 if (g1p->track_object_age(alloc_purpose)) {
3648 // We could simply do obj->incr_age(). However, this causes a
3649 // performance issue. obj->incr_age() will first check whether
3650 // the object has a displaced mark by checking its mark word;
3651 // getting the mark word from the new location of the object
3652 // stalls. So, given that we already have the mark word and we
3653 // are about to install it anyway, it's better to increase the
3654 // age on the mark word, when the object does not have a
3655 // displaced mark word. We're not expecting many objects to have
3656 // a displaced marked word, so that case is not optimized
3657 // further (it could be...) and we simply call obj->incr_age().
3659 if (m->has_displaced_mark_helper()) {
3660 // in this case, we have to install the mark word first,
3661 // otherwise obj looks to be forwarded (the old mark word,
3662 // which contains the forward pointer, was copied)
3663 obj->set_mark(m);
3664 obj->incr_age();
3665 } else {
3666 m = m->incr_age();
3667 obj->set_mark(m);
3668 }
3669 _par_scan_state->age_table()->add(obj, word_sz);
3670 } else {
3671 obj->set_mark(m);
3672 }
3674 // preserve "next" mark bit
3675 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3676 if (!use_local_bitmaps ||
3677 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3678 // if we couldn't mark it on the local bitmap (this happens when
3679 // the object was not allocated in the GCLab), we have to bite
3680 // the bullet and do the standard parallel mark
3681 _cm->markAndGrayObjectIfNecessary(obj);
3682 }
3683 #if 1
3684 if (_g1->isMarkedNext(old)) {
3685 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3686 }
3687 #endif
3688 }
3690 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3691 surv_young_words[young_index] += word_sz;
3693 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3694 arrayOop(old)->set_length(0);
3695 oop* old_p = set_partial_array_mask(old);
3696 _par_scan_state->push_on_queue(old_p);
3697 } else {
3698 // No point in using the slower heap_region_containing() method,
3699 // given that we know obj is in the heap.
3700 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3701 obj->oop_iterate_backwards(_scanner);
3702 }
3703 } else {
3704 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3705 obj = forward_ptr;
3706 }
3707 return obj;
3708 }
3710 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee, bool skip_cset_test>
3711 template <class T>
3712 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee, skip_cset_test>
3713 ::do_oop_work(T* p) {
3714 oop obj = oopDesc::load_decode_heap_oop(p);
3715 assert(barrier != G1BarrierRS || obj != NULL,
3716 "Precondition: G1BarrierRS implies obj is nonNull");
3718 // The only time we skip the cset test is when we're scanning
3719 // references popped from the queue. And we only push on the queue
3720 // references that we know point into the cset, so no point in
3721 // checking again. But we'll leave an assert here for peace of mind.
3722 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
3724 // here the null check is implicit in the cset_fast_test() test
3725 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
3726 #if G1_REM_SET_LOGGING
3727 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
3728 "into CS.", p, (void*) obj);
3729 #endif
3730 if (obj->is_forwarded()) {
3731 oopDesc::encode_store_heap_oop(p, obj->forwardee());
3732 } else {
3733 oop copy_oop = copy_to_survivor_space(obj);
3734 oopDesc::encode_store_heap_oop(p, copy_oop);
3735 }
3736 // When scanning the RS, we only care about objs in CS.
3737 if (barrier == G1BarrierRS) {
3738 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3739 }
3740 }
3742 // When scanning moved objs, must look at all oops.
3743 if (barrier == G1BarrierEvac && obj != NULL) {
3744 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3745 }
3747 if (do_gen_barrier && obj != NULL) {
3748 par_do_barrier(p);
3749 }
3750 }
3752 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
3753 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(narrowOop* p);
3755 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
3756 assert(has_partial_array_mask(p), "invariant");
3757 oop old = clear_partial_array_mask(p);
3758 assert(old->is_objArray(), "must be obj array");
3759 assert(old->is_forwarded(), "must be forwarded");
3760 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
3762 objArrayOop obj = objArrayOop(old->forwardee());
3763 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
3764 // Process ParGCArrayScanChunk elements now
3765 // and push the remainder back onto queue
3766 int start = arrayOop(old)->length();
3767 int end = obj->length();
3768 int remainder = end - start;
3769 assert(start <= end, "just checking");
3770 if (remainder > 2 * ParGCArrayScanChunk) {
3771 // Test above combines last partial chunk with a full chunk
3772 end = start + ParGCArrayScanChunk;
3773 arrayOop(old)->set_length(end);
3774 // Push remainder.
3775 oop* old_p = set_partial_array_mask(old);
3776 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
3777 _par_scan_state->push_on_queue(old_p);
3778 } else {
3779 // Restore length so that the heap remains parsable in
3780 // case of evacuation failure.
3781 arrayOop(old)->set_length(end);
3782 }
3783 _scanner.set_region(_g1->heap_region_containing_raw(obj));
3784 // process our set of indices (include header in first chunk)
3785 obj->oop_iterate_range(&_scanner, start, end);
3786 }
3788 class G1ParEvacuateFollowersClosure : public VoidClosure {
3789 protected:
3790 G1CollectedHeap* _g1h;
3791 G1ParScanThreadState* _par_scan_state;
3792 RefToScanQueueSet* _queues;
3793 ParallelTaskTerminator* _terminator;
3795 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3796 RefToScanQueueSet* queues() { return _queues; }
3797 ParallelTaskTerminator* terminator() { return _terminator; }
3799 public:
3800 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
3801 G1ParScanThreadState* par_scan_state,
3802 RefToScanQueueSet* queues,
3803 ParallelTaskTerminator* terminator)
3804 : _g1h(g1h), _par_scan_state(par_scan_state),
3805 _queues(queues), _terminator(terminator) {}
3807 void do_void() {
3808 G1ParScanThreadState* pss = par_scan_state();
3809 while (true) {
3810 pss->trim_queue();
3811 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
3813 StarTask stolen_task;
3814 if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
3815 IF_G1_DETAILED_STATS(pss->note_steal());
3817 // slightly paranoid tests; I'm trying to catch potential
3818 // problems before we go into push_on_queue to know where the
3819 // problem is coming from
3820 assert((oop*)stolen_task != NULL, "Error");
3821 if (stolen_task.is_narrow()) {
3822 assert(UseCompressedOops, "Error");
3823 narrowOop* p = (narrowOop*) stolen_task;
3824 assert(has_partial_array_mask(p) ||
3825 _g1h->obj_in_cs(oopDesc::load_decode_heap_oop(p)), "Error");
3826 pss->push_on_queue(p);
3827 } else {
3828 oop* p = (oop*) stolen_task;
3829 assert(has_partial_array_mask(p) || _g1h->obj_in_cs(*p), "Error");
3830 pss->push_on_queue(p);
3831 }
3832 continue;
3833 }
3834 pss->start_term_time();
3835 if (terminator()->offer_termination()) break;
3836 pss->end_term_time();
3837 }
3838 pss->end_term_time();
3839 pss->retire_alloc_buffers();
3840 }
3841 };
3843 class G1ParTask : public AbstractGangTask {
3844 protected:
3845 G1CollectedHeap* _g1h;
3846 RefToScanQueueSet *_queues;
3847 ParallelTaskTerminator _terminator;
3848 int _n_workers;
3850 Mutex _stats_lock;
3851 Mutex* stats_lock() { return &_stats_lock; }
3853 size_t getNCards() {
3854 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
3855 / G1BlockOffsetSharedArray::N_bytes;
3856 }
3858 public:
3859 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
3860 : AbstractGangTask("G1 collection"),
3861 _g1h(g1h),
3862 _queues(task_queues),
3863 _terminator(workers, _queues),
3864 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
3865 _n_workers(workers)
3866 {}
3868 RefToScanQueueSet* queues() { return _queues; }
3870 RefToScanQueue *work_queue(int i) {
3871 return queues()->queue(i);
3872 }
3874 void work(int i) {
3875 if (i >= _n_workers) return; // no work needed this round
3876 ResourceMark rm;
3877 HandleMark hm;
3879 G1ParScanThreadState pss(_g1h, i);
3880 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
3881 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
3882 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
3884 pss.set_evac_closure(&scan_evac_cl);
3885 pss.set_evac_failure_closure(&evac_failure_cl);
3886 pss.set_partial_scan_closure(&partial_scan_cl);
3888 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
3889 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
3890 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
3892 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
3893 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
3894 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
3896 OopsInHeapRegionClosure *scan_root_cl;
3897 OopsInHeapRegionClosure *scan_perm_cl;
3898 OopsInHeapRegionClosure *scan_so_cl;
3900 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
3901 scan_root_cl = &scan_mark_root_cl;
3902 scan_perm_cl = &scan_mark_perm_cl;
3903 scan_so_cl = &scan_mark_heap_rs_cl;
3904 } else {
3905 scan_root_cl = &only_scan_root_cl;
3906 scan_perm_cl = &only_scan_perm_cl;
3907 scan_so_cl = &only_scan_heap_rs_cl;
3908 }
3910 pss.start_strong_roots();
3911 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
3912 SharedHeap::SO_AllClasses,
3913 scan_root_cl,
3914 &only_scan_heap_rs_cl,
3915 scan_so_cl,
3916 scan_perm_cl,
3917 i);
3918 pss.end_strong_roots();
3919 {
3920 double start = os::elapsedTime();
3921 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
3922 evac.do_void();
3923 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
3924 double term_ms = pss.term_time()*1000.0;
3925 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
3926 _g1h->g1_policy()->record_termination_time(i, term_ms);
3927 }
3928 if (G1UseSurvivorSpaces) {
3929 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
3930 }
3931 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
3933 // Clean up any par-expanded rem sets.
3934 HeapRegionRemSet::par_cleanup();
3936 MutexLocker x(stats_lock());
3937 if (ParallelGCVerbose) {
3938 gclog_or_tty->print("Thread %d complete:\n", i);
3939 #if G1_DETAILED_STATS
3940 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
3941 pss.pushes(),
3942 pss.pops(),
3943 pss.overflow_pushes(),
3944 pss.steals(),
3945 pss.steal_attempts());
3946 #endif
3947 double elapsed = pss.elapsed();
3948 double strong_roots = pss.strong_roots_time();
3949 double term = pss.term_time();
3950 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
3951 " Strong roots: %7.2f ms (%6.2f%%)\n"
3952 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
3953 elapsed * 1000.0,
3954 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
3955 term * 1000.0, (term*100.0/elapsed),
3956 pss.term_attempts());
3957 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
3958 gclog_or_tty->print(" Waste: %8dK\n"
3959 " Alloc Buffer: %8dK\n"
3960 " Undo: %8dK\n",
3961 (total_waste * HeapWordSize) / K,
3962 (pss.alloc_buffer_waste() * HeapWordSize) / K,
3963 (pss.undo_waste() * HeapWordSize) / K);
3964 }
3966 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
3967 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
3968 }
3969 };
3971 // *** Common G1 Evacuation Stuff
3973 void
3974 G1CollectedHeap::
3975 g1_process_strong_roots(bool collecting_perm_gen,
3976 SharedHeap::ScanningOption so,
3977 OopClosure* scan_non_heap_roots,
3978 OopsInHeapRegionClosure* scan_rs,
3979 OopsInHeapRegionClosure* scan_so,
3980 OopsInGenClosure* scan_perm,
3981 int worker_i) {
3982 // First scan the strong roots, including the perm gen.
3983 double ext_roots_start = os::elapsedTime();
3984 double closure_app_time_sec = 0.0;
3986 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
3987 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
3988 buf_scan_perm.set_generation(perm_gen());
3990 process_strong_roots(collecting_perm_gen, so,
3991 &buf_scan_non_heap_roots,
3992 &buf_scan_perm);
3993 // Finish up any enqueued closure apps.
3994 buf_scan_non_heap_roots.done();
3995 buf_scan_perm.done();
3996 double ext_roots_end = os::elapsedTime();
3997 g1_policy()->reset_obj_copy_time(worker_i);
3998 double obj_copy_time_sec =
3999 buf_scan_non_heap_roots.closure_app_seconds() +
4000 buf_scan_perm.closure_app_seconds();
4001 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4002 double ext_root_time_ms =
4003 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4004 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4006 // Scan strong roots in mark stack.
4007 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4008 concurrent_mark()->oops_do(scan_non_heap_roots);
4009 }
4010 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4011 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4013 // XXX What should this be doing in the parallel case?
4014 g1_policy()->record_collection_pause_end_CH_strong_roots();
4015 if (scan_so != NULL) {
4016 scan_scan_only_set(scan_so, worker_i);
4017 }
4018 // Now scan the complement of the collection set.
4019 if (scan_rs != NULL) {
4020 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4021 }
4022 // Finish with the ref_processor roots.
4023 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4024 ref_processor()->oops_do(scan_non_heap_roots);
4025 }
4026 g1_policy()->record_collection_pause_end_G1_strong_roots();
4027 _process_strong_tasks->all_tasks_completed();
4028 }
4030 void
4031 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4032 OopsInHeapRegionClosure* oc,
4033 int worker_i) {
4034 HeapWord* startAddr = r->bottom();
4035 HeapWord* endAddr = r->used_region().end();
4037 oc->set_region(r);
4039 HeapWord* p = r->bottom();
4040 HeapWord* t = r->top();
4041 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4042 while (p < t) {
4043 oop obj = oop(p);
4044 p += obj->oop_iterate(oc);
4045 }
4046 }
4048 void
4049 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4050 int worker_i) {
4051 double start = os::elapsedTime();
4053 BufferingOopsInHeapRegionClosure boc(oc);
4055 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4056 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4058 OopsInHeapRegionClosure *foc;
4059 if (g1_policy()->should_initiate_conc_mark())
4060 foc = &scan_and_mark;
4061 else
4062 foc = &scan_only;
4064 HeapRegion* hr;
4065 int n = 0;
4066 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4067 scan_scan_only_region(hr, foc, worker_i);
4068 ++n;
4069 }
4070 boc.done();
4072 double closure_app_s = boc.closure_app_seconds();
4073 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4074 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4075 g1_policy()->record_scan_only_time(worker_i, ms, n);
4076 }
4078 void
4079 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4080 OopClosure* non_root_closure) {
4081 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4082 }
4085 class SaveMarksClosure: public HeapRegionClosure {
4086 public:
4087 bool doHeapRegion(HeapRegion* r) {
4088 r->save_marks();
4089 return false;
4090 }
4091 };
4093 void G1CollectedHeap::save_marks() {
4094 if (ParallelGCThreads == 0) {
4095 SaveMarksClosure sm;
4096 heap_region_iterate(&sm);
4097 }
4098 // We do this even in the parallel case
4099 perm_gen()->save_marks();
4100 }
4102 void G1CollectedHeap::evacuate_collection_set() {
4103 set_evacuation_failed(false);
4105 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4106 concurrent_g1_refine()->set_use_cache(false);
4107 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4109 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4110 set_par_threads(n_workers);
4111 G1ParTask g1_par_task(this, n_workers, _task_queues);
4113 init_for_evac_failure(NULL);
4115 change_strong_roots_parity(); // In preparation for parallel strong roots.
4116 rem_set()->prepare_for_younger_refs_iterate(true);
4118 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4119 double start_par = os::elapsedTime();
4120 if (ParallelGCThreads > 0) {
4121 // The individual threads will set their evac-failure closures.
4122 workers()->run_task(&g1_par_task);
4123 } else {
4124 g1_par_task.work(0);
4125 }
4127 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4128 g1_policy()->record_par_time(par_time);
4129 set_par_threads(0);
4130 // Is this the right thing to do here? We don't save marks
4131 // on individual heap regions when we allocate from
4132 // them in parallel, so this seems like the correct place for this.
4133 retire_all_alloc_regions();
4134 {
4135 G1IsAliveClosure is_alive(this);
4136 G1KeepAliveClosure keep_alive(this);
4137 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4138 }
4139 release_gc_alloc_regions(false /* totally */);
4140 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4142 concurrent_g1_refine()->clear_hot_cache();
4143 concurrent_g1_refine()->set_use_cache(true);
4145 finalize_for_evac_failure();
4147 // Must do this before removing self-forwarding pointers, which clears
4148 // the per-region evac-failure flags.
4149 concurrent_mark()->complete_marking_in_collection_set();
4151 if (evacuation_failed()) {
4152 remove_self_forwarding_pointers();
4153 if (PrintGCDetails) {
4154 gclog_or_tty->print(" (evacuation failed)");
4155 } else if (PrintGC) {
4156 gclog_or_tty->print("--");
4157 }
4158 }
4160 if (G1DeferredRSUpdate) {
4161 RedirtyLoggedCardTableEntryFastClosure redirty;
4162 dirty_card_queue_set().set_closure(&redirty);
4163 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4164 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4165 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4166 }
4168 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4169 }
4171 void G1CollectedHeap::free_region(HeapRegion* hr) {
4172 size_t pre_used = 0;
4173 size_t cleared_h_regions = 0;
4174 size_t freed_regions = 0;
4175 UncleanRegionList local_list;
4177 HeapWord* start = hr->bottom();
4178 HeapWord* end = hr->prev_top_at_mark_start();
4179 size_t used_bytes = hr->used();
4180 size_t live_bytes = hr->max_live_bytes();
4181 if (used_bytes > 0) {
4182 guarantee( live_bytes <= used_bytes, "invariant" );
4183 } else {
4184 guarantee( live_bytes == 0, "invariant" );
4185 }
4187 size_t garbage_bytes = used_bytes - live_bytes;
4188 if (garbage_bytes > 0)
4189 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4191 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4192 &local_list);
4193 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4194 &local_list);
4195 }
4197 void
4198 G1CollectedHeap::free_region_work(HeapRegion* hr,
4199 size_t& pre_used,
4200 size_t& cleared_h_regions,
4201 size_t& freed_regions,
4202 UncleanRegionList* list,
4203 bool par) {
4204 pre_used += hr->used();
4205 if (hr->isHumongous()) {
4206 assert(hr->startsHumongous(),
4207 "Only the start of a humongous region should be freed.");
4208 int ind = _hrs->find(hr);
4209 assert(ind != -1, "Should have an index.");
4210 // Clear the start region.
4211 hr->hr_clear(par, true /*clear_space*/);
4212 list->insert_before_head(hr);
4213 cleared_h_regions++;
4214 freed_regions++;
4215 // Clear any continued regions.
4216 ind++;
4217 while ((size_t)ind < n_regions()) {
4218 HeapRegion* hrc = _hrs->at(ind);
4219 if (!hrc->continuesHumongous()) break;
4220 // Otherwise, does continue the H region.
4221 assert(hrc->humongous_start_region() == hr, "Huh?");
4222 hrc->hr_clear(par, true /*clear_space*/);
4223 cleared_h_regions++;
4224 freed_regions++;
4225 list->insert_before_head(hrc);
4226 ind++;
4227 }
4228 } else {
4229 hr->hr_clear(par, true /*clear_space*/);
4230 list->insert_before_head(hr);
4231 freed_regions++;
4232 // If we're using clear2, this should not be enabled.
4233 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4234 }
4235 }
4237 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4238 size_t cleared_h_regions,
4239 size_t freed_regions,
4240 UncleanRegionList* list) {
4241 if (list != NULL && list->sz() > 0) {
4242 prepend_region_list_on_unclean_list(list);
4243 }
4244 // Acquire a lock, if we're parallel, to update possibly-shared
4245 // variables.
4246 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4247 {
4248 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4249 _summary_bytes_used -= pre_used;
4250 _num_humongous_regions -= (int) cleared_h_regions;
4251 _free_regions += freed_regions;
4252 }
4253 }
4256 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4257 while (list != NULL) {
4258 guarantee( list->is_young(), "invariant" );
4260 HeapWord* bottom = list->bottom();
4261 HeapWord* end = list->end();
4262 MemRegion mr(bottom, end);
4263 ct_bs->dirty(mr);
4265 list = list->get_next_young_region();
4266 }
4267 }
4270 class G1ParCleanupCTTask : public AbstractGangTask {
4271 CardTableModRefBS* _ct_bs;
4272 G1CollectedHeap* _g1h;
4273 HeapRegion* volatile _so_head;
4274 HeapRegion* volatile _su_head;
4275 public:
4276 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4277 G1CollectedHeap* g1h,
4278 HeapRegion* scan_only_list,
4279 HeapRegion* survivor_list) :
4280 AbstractGangTask("G1 Par Cleanup CT Task"),
4281 _ct_bs(ct_bs),
4282 _g1h(g1h),
4283 _so_head(scan_only_list),
4284 _su_head(survivor_list)
4285 { }
4287 void work(int i) {
4288 HeapRegion* r;
4289 while (r = _g1h->pop_dirty_cards_region()) {
4290 clear_cards(r);
4291 }
4292 // Redirty the cards of the scan-only and survivor regions.
4293 dirty_list(&this->_so_head);
4294 dirty_list(&this->_su_head);
4295 }
4297 void clear_cards(HeapRegion* r) {
4298 // Cards for Survivor and Scan-Only regions will be dirtied later.
4299 if (!r->is_scan_only() && !r->is_survivor()) {
4300 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4301 }
4302 }
4304 void dirty_list(HeapRegion* volatile * head_ptr) {
4305 HeapRegion* head;
4306 do {
4307 // Pop region off the list.
4308 head = *head_ptr;
4309 if (head != NULL) {
4310 HeapRegion* r = (HeapRegion*)
4311 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4312 if (r == head) {
4313 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4314 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4315 }
4316 }
4317 } while (*head_ptr != NULL);
4318 }
4319 };
4322 #ifndef PRODUCT
4323 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4324 CardTableModRefBS* _ct_bs;
4325 public:
4326 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4327 : _ct_bs(ct_bs)
4328 { }
4329 virtual bool doHeapRegion(HeapRegion* r)
4330 {
4331 MemRegion mr(r->bottom(), r->end());
4332 if (r->is_scan_only() || r->is_survivor()) {
4333 _ct_bs->verify_dirty_region(mr);
4334 } else {
4335 _ct_bs->verify_clean_region(mr);
4336 }
4337 return false;
4338 }
4339 };
4340 #endif
4342 void G1CollectedHeap::cleanUpCardTable() {
4343 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4344 double start = os::elapsedTime();
4346 // Iterate over the dirty cards region list.
4347 G1ParCleanupCTTask cleanup_task(ct_bs, this,
4348 _young_list->first_scan_only_region(),
4349 _young_list->first_survivor_region());
4350 if (ParallelGCThreads > 0) {
4351 set_par_threads(workers()->total_workers());
4352 workers()->run_task(&cleanup_task);
4353 set_par_threads(0);
4354 } else {
4355 while (_dirty_cards_region_list) {
4356 HeapRegion* r = _dirty_cards_region_list;
4357 cleanup_task.clear_cards(r);
4358 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4359 if (_dirty_cards_region_list == r) {
4360 // The last region.
4361 _dirty_cards_region_list = NULL;
4362 }
4363 r->set_next_dirty_cards_region(NULL);
4364 }
4365 // now, redirty the cards of the scan-only and survivor regions
4366 // (it seemed faster to do it this way, instead of iterating over
4367 // all regions and then clearing / dirtying as appropriate)
4368 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4369 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4370 }
4371 double elapsed = os::elapsedTime() - start;
4372 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4373 #ifndef PRODUCT
4374 if (G1VerifyCTCleanup || VerifyAfterGC) {
4375 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
4376 heap_region_iterate(&cleanup_verifier);
4377 }
4378 #endif
4379 }
4381 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4382 if (g1_policy()->should_do_collection_pause(word_size)) {
4383 do_collection_pause();
4384 }
4385 }
4387 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4388 double young_time_ms = 0.0;
4389 double non_young_time_ms = 0.0;
4391 G1CollectorPolicy* policy = g1_policy();
4393 double start_sec = os::elapsedTime();
4394 bool non_young = true;
4396 HeapRegion* cur = cs_head;
4397 int age_bound = -1;
4398 size_t rs_lengths = 0;
4400 while (cur != NULL) {
4401 if (non_young) {
4402 if (cur->is_young()) {
4403 double end_sec = os::elapsedTime();
4404 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4405 non_young_time_ms += elapsed_ms;
4407 start_sec = os::elapsedTime();
4408 non_young = false;
4409 }
4410 } else {
4411 if (!cur->is_on_free_list()) {
4412 double end_sec = os::elapsedTime();
4413 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4414 young_time_ms += elapsed_ms;
4416 start_sec = os::elapsedTime();
4417 non_young = true;
4418 }
4419 }
4421 rs_lengths += cur->rem_set()->occupied();
4423 HeapRegion* next = cur->next_in_collection_set();
4424 assert(cur->in_collection_set(), "bad CS");
4425 cur->set_next_in_collection_set(NULL);
4426 cur->set_in_collection_set(false);
4428 if (cur->is_young()) {
4429 int index = cur->young_index_in_cset();
4430 guarantee( index != -1, "invariant" );
4431 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4432 size_t words_survived = _surviving_young_words[index];
4433 cur->record_surv_words_in_group(words_survived);
4434 } else {
4435 int index = cur->young_index_in_cset();
4436 guarantee( index == -1, "invariant" );
4437 }
4439 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4440 (!cur->is_young() && cur->young_index_in_cset() == -1),
4441 "invariant" );
4443 if (!cur->evacuation_failed()) {
4444 // And the region is empty.
4445 assert(!cur->is_empty(),
4446 "Should not have empty regions in a CS.");
4447 free_region(cur);
4448 } else {
4449 guarantee( !cur->is_scan_only(), "should not be scan only" );
4450 cur->uninstall_surv_rate_group();
4451 if (cur->is_young())
4452 cur->set_young_index_in_cset(-1);
4453 cur->set_not_young();
4454 cur->set_evacuation_failed(false);
4455 }
4456 cur = next;
4457 }
4459 policy->record_max_rs_lengths(rs_lengths);
4460 policy->cset_regions_freed();
4462 double end_sec = os::elapsedTime();
4463 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4464 if (non_young)
4465 non_young_time_ms += elapsed_ms;
4466 else
4467 young_time_ms += elapsed_ms;
4469 policy->record_young_free_cset_time_ms(young_time_ms);
4470 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4471 }
4473 HeapRegion*
4474 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4475 assert(ZF_mon->owned_by_self(), "Precondition");
4476 HeapRegion* res = pop_unclean_region_list_locked();
4477 if (res != NULL) {
4478 assert(!res->continuesHumongous() &&
4479 res->zero_fill_state() != HeapRegion::Allocated,
4480 "Only free regions on unclean list.");
4481 if (zero_filled) {
4482 res->ensure_zero_filled_locked();
4483 res->set_zero_fill_allocated();
4484 }
4485 }
4486 return res;
4487 }
4489 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4490 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4491 return alloc_region_from_unclean_list_locked(zero_filled);
4492 }
4494 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4495 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4496 put_region_on_unclean_list_locked(r);
4497 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4498 }
4500 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4501 MutexLockerEx x(Cleanup_mon);
4502 set_unclean_regions_coming_locked(b);
4503 }
4505 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4506 assert(Cleanup_mon->owned_by_self(), "Precondition");
4507 _unclean_regions_coming = b;
4508 // Wake up mutator threads that might be waiting for completeCleanup to
4509 // finish.
4510 if (!b) Cleanup_mon->notify_all();
4511 }
4513 void G1CollectedHeap::wait_for_cleanup_complete() {
4514 MutexLockerEx x(Cleanup_mon);
4515 wait_for_cleanup_complete_locked();
4516 }
4518 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4519 assert(Cleanup_mon->owned_by_self(), "precondition");
4520 while (_unclean_regions_coming) {
4521 Cleanup_mon->wait();
4522 }
4523 }
4525 void
4526 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4527 assert(ZF_mon->owned_by_self(), "precondition.");
4528 _unclean_region_list.insert_before_head(r);
4529 }
4531 void
4532 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4533 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4534 prepend_region_list_on_unclean_list_locked(list);
4535 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4536 }
4538 void
4539 G1CollectedHeap::
4540 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4541 assert(ZF_mon->owned_by_self(), "precondition.");
4542 _unclean_region_list.prepend_list(list);
4543 }
4545 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4546 assert(ZF_mon->owned_by_self(), "precondition.");
4547 HeapRegion* res = _unclean_region_list.pop();
4548 if (res != NULL) {
4549 // Inform ZF thread that there's a new unclean head.
4550 if (_unclean_region_list.hd() != NULL && should_zf())
4551 ZF_mon->notify_all();
4552 }
4553 return res;
4554 }
4556 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4557 assert(ZF_mon->owned_by_self(), "precondition.");
4558 return _unclean_region_list.hd();
4559 }
4562 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4563 assert(ZF_mon->owned_by_self(), "Precondition");
4564 HeapRegion* r = peek_unclean_region_list_locked();
4565 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4566 // Result of below must be equal to "r", since we hold the lock.
4567 (void)pop_unclean_region_list_locked();
4568 put_free_region_on_list_locked(r);
4569 return true;
4570 } else {
4571 return false;
4572 }
4573 }
4575 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4576 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4577 return move_cleaned_region_to_free_list_locked();
4578 }
4581 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4582 assert(ZF_mon->owned_by_self(), "precondition.");
4583 assert(_free_region_list_size == free_region_list_length(), "Inv");
4584 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4585 "Regions on free list must be zero filled");
4586 assert(!r->isHumongous(), "Must not be humongous.");
4587 assert(r->is_empty(), "Better be empty");
4588 assert(!r->is_on_free_list(),
4589 "Better not already be on free list");
4590 assert(!r->is_on_unclean_list(),
4591 "Better not already be on unclean list");
4592 r->set_on_free_list(true);
4593 r->set_next_on_free_list(_free_region_list);
4594 _free_region_list = r;
4595 _free_region_list_size++;
4596 assert(_free_region_list_size == free_region_list_length(), "Inv");
4597 }
4599 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4600 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4601 put_free_region_on_list_locked(r);
4602 }
4604 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4605 assert(ZF_mon->owned_by_self(), "precondition.");
4606 assert(_free_region_list_size == free_region_list_length(), "Inv");
4607 HeapRegion* res = _free_region_list;
4608 if (res != NULL) {
4609 _free_region_list = res->next_from_free_list();
4610 _free_region_list_size--;
4611 res->set_on_free_list(false);
4612 res->set_next_on_free_list(NULL);
4613 assert(_free_region_list_size == free_region_list_length(), "Inv");
4614 }
4615 return res;
4616 }
4619 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4620 // By self, or on behalf of self.
4621 assert(Heap_lock->is_locked(), "Precondition");
4622 HeapRegion* res = NULL;
4623 bool first = true;
4624 while (res == NULL) {
4625 if (zero_filled || !first) {
4626 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4627 res = pop_free_region_list_locked();
4628 if (res != NULL) {
4629 assert(!res->zero_fill_is_allocated(),
4630 "No allocated regions on free list.");
4631 res->set_zero_fill_allocated();
4632 } else if (!first) {
4633 break; // We tried both, time to return NULL.
4634 }
4635 }
4637 if (res == NULL) {
4638 res = alloc_region_from_unclean_list(zero_filled);
4639 }
4640 assert(res == NULL ||
4641 !zero_filled ||
4642 res->zero_fill_is_allocated(),
4643 "We must have allocated the region we're returning");
4644 first = false;
4645 }
4646 return res;
4647 }
4649 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4650 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4651 {
4652 HeapRegion* prev = NULL;
4653 HeapRegion* cur = _unclean_region_list.hd();
4654 while (cur != NULL) {
4655 HeapRegion* next = cur->next_from_unclean_list();
4656 if (cur->zero_fill_is_allocated()) {
4657 // Remove from the list.
4658 if (prev == NULL) {
4659 (void)_unclean_region_list.pop();
4660 } else {
4661 _unclean_region_list.delete_after(prev);
4662 }
4663 cur->set_on_unclean_list(false);
4664 cur->set_next_on_unclean_list(NULL);
4665 } else {
4666 prev = cur;
4667 }
4668 cur = next;
4669 }
4670 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4671 "Inv");
4672 }
4674 {
4675 HeapRegion* prev = NULL;
4676 HeapRegion* cur = _free_region_list;
4677 while (cur != NULL) {
4678 HeapRegion* next = cur->next_from_free_list();
4679 if (cur->zero_fill_is_allocated()) {
4680 // Remove from the list.
4681 if (prev == NULL) {
4682 _free_region_list = cur->next_from_free_list();
4683 } else {
4684 prev->set_next_on_free_list(cur->next_from_free_list());
4685 }
4686 cur->set_on_free_list(false);
4687 cur->set_next_on_free_list(NULL);
4688 _free_region_list_size--;
4689 } else {
4690 prev = cur;
4691 }
4692 cur = next;
4693 }
4694 assert(_free_region_list_size == free_region_list_length(), "Inv");
4695 }
4696 }
4698 bool G1CollectedHeap::verify_region_lists() {
4699 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4700 return verify_region_lists_locked();
4701 }
4703 bool G1CollectedHeap::verify_region_lists_locked() {
4704 HeapRegion* unclean = _unclean_region_list.hd();
4705 while (unclean != NULL) {
4706 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4707 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4708 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4709 "Everything else is possible.");
4710 unclean = unclean->next_from_unclean_list();
4711 }
4712 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4714 HeapRegion* free_r = _free_region_list;
4715 while (free_r != NULL) {
4716 assert(free_r->is_on_free_list(), "Well, it is!");
4717 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4718 switch (free_r->zero_fill_state()) {
4719 case HeapRegion::NotZeroFilled:
4720 case HeapRegion::ZeroFilling:
4721 guarantee(false, "Should not be on free list.");
4722 break;
4723 default:
4724 // Everything else is possible.
4725 break;
4726 }
4727 free_r = free_r->next_from_free_list();
4728 }
4729 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4730 // If we didn't do an assertion...
4731 return true;
4732 }
4734 size_t G1CollectedHeap::free_region_list_length() {
4735 assert(ZF_mon->owned_by_self(), "precondition.");
4736 size_t len = 0;
4737 HeapRegion* cur = _free_region_list;
4738 while (cur != NULL) {
4739 len++;
4740 cur = cur->next_from_free_list();
4741 }
4742 return len;
4743 }
4745 size_t G1CollectedHeap::unclean_region_list_length() {
4746 assert(ZF_mon->owned_by_self(), "precondition.");
4747 return _unclean_region_list.length();
4748 }
4750 size_t G1CollectedHeap::n_regions() {
4751 return _hrs->length();
4752 }
4754 size_t G1CollectedHeap::max_regions() {
4755 return
4756 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4757 HeapRegion::GrainBytes;
4758 }
4760 size_t G1CollectedHeap::free_regions() {
4761 /* Possibly-expensive assert.
4762 assert(_free_regions == count_free_regions(),
4763 "_free_regions is off.");
4764 */
4765 return _free_regions;
4766 }
4768 bool G1CollectedHeap::should_zf() {
4769 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4770 }
4772 class RegionCounter: public HeapRegionClosure {
4773 size_t _n;
4774 public:
4775 RegionCounter() : _n(0) {}
4776 bool doHeapRegion(HeapRegion* r) {
4777 if (r->is_empty()) {
4778 assert(!r->isHumongous(), "H regions should not be empty.");
4779 _n++;
4780 }
4781 return false;
4782 }
4783 int res() { return (int) _n; }
4784 };
4786 size_t G1CollectedHeap::count_free_regions() {
4787 RegionCounter rc;
4788 heap_region_iterate(&rc);
4789 size_t n = rc.res();
4790 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4791 n--;
4792 return n;
4793 }
4795 size_t G1CollectedHeap::count_free_regions_list() {
4796 size_t n = 0;
4797 size_t o = 0;
4798 ZF_mon->lock_without_safepoint_check();
4799 HeapRegion* cur = _free_region_list;
4800 while (cur != NULL) {
4801 cur = cur->next_from_free_list();
4802 n++;
4803 }
4804 size_t m = unclean_region_list_length();
4805 ZF_mon->unlock();
4806 return n + m;
4807 }
4809 bool G1CollectedHeap::should_set_young_locked() {
4810 assert(heap_lock_held_for_gc(),
4811 "the heap lock should already be held by or for this thread");
4812 return (g1_policy()->in_young_gc_mode() &&
4813 g1_policy()->should_add_next_region_to_young_list());
4814 }
4816 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4817 assert(heap_lock_held_for_gc(),
4818 "the heap lock should already be held by or for this thread");
4819 _young_list->push_region(hr);
4820 g1_policy()->set_region_short_lived(hr);
4821 }
4823 class NoYoungRegionsClosure: public HeapRegionClosure {
4824 private:
4825 bool _success;
4826 public:
4827 NoYoungRegionsClosure() : _success(true) { }
4828 bool doHeapRegion(HeapRegion* r) {
4829 if (r->is_young()) {
4830 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
4831 r->bottom(), r->end());
4832 _success = false;
4833 }
4834 return false;
4835 }
4836 bool success() { return _success; }
4837 };
4839 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
4840 bool check_sample) {
4841 bool ret = true;
4843 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
4844 if (!ignore_scan_only_list) {
4845 NoYoungRegionsClosure closure;
4846 heap_region_iterate(&closure);
4847 ret = ret && closure.success();
4848 }
4850 return ret;
4851 }
4853 void G1CollectedHeap::empty_young_list() {
4854 assert(heap_lock_held_for_gc(),
4855 "the heap lock should already be held by or for this thread");
4856 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
4858 _young_list->empty_list();
4859 }
4861 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
4862 bool no_allocs = true;
4863 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
4864 HeapRegion* r = _gc_alloc_regions[ap];
4865 no_allocs = r == NULL || r->saved_mark_at_top();
4866 }
4867 return no_allocs;
4868 }
4870 void G1CollectedHeap::retire_all_alloc_regions() {
4871 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4872 HeapRegion* r = _gc_alloc_regions[ap];
4873 if (r != NULL) {
4874 // Check for aliases.
4875 bool has_processed_alias = false;
4876 for (int i = 0; i < ap; ++i) {
4877 if (_gc_alloc_regions[i] == r) {
4878 has_processed_alias = true;
4879 break;
4880 }
4881 }
4882 if (!has_processed_alias) {
4883 retire_alloc_region(r, false /* par */);
4884 }
4885 }
4886 }
4887 }
4890 // Done at the start of full GC.
4891 void G1CollectedHeap::tear_down_region_lists() {
4892 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4893 while (pop_unclean_region_list_locked() != NULL) ;
4894 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
4895 "Postconditions of loop.")
4896 while (pop_free_region_list_locked() != NULL) ;
4897 assert(_free_region_list == NULL, "Postcondition of loop.");
4898 if (_free_region_list_size != 0) {
4899 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
4900 print_on(gclog_or_tty, true /* extended */);
4901 }
4902 assert(_free_region_list_size == 0, "Postconditions of loop.");
4903 }
4906 class RegionResetter: public HeapRegionClosure {
4907 G1CollectedHeap* _g1;
4908 int _n;
4909 public:
4910 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4911 bool doHeapRegion(HeapRegion* r) {
4912 if (r->continuesHumongous()) return false;
4913 if (r->top() > r->bottom()) {
4914 if (r->top() < r->end()) {
4915 Copy::fill_to_words(r->top(),
4916 pointer_delta(r->end(), r->top()));
4917 }
4918 r->set_zero_fill_allocated();
4919 } else {
4920 assert(r->is_empty(), "tautology");
4921 _n++;
4922 switch (r->zero_fill_state()) {
4923 case HeapRegion::NotZeroFilled:
4924 case HeapRegion::ZeroFilling:
4925 _g1->put_region_on_unclean_list_locked(r);
4926 break;
4927 case HeapRegion::Allocated:
4928 r->set_zero_fill_complete();
4929 // no break; go on to put on free list.
4930 case HeapRegion::ZeroFilled:
4931 _g1->put_free_region_on_list_locked(r);
4932 break;
4933 }
4934 }
4935 return false;
4936 }
4938 int getFreeRegionCount() {return _n;}
4939 };
4941 // Done at the end of full GC.
4942 void G1CollectedHeap::rebuild_region_lists() {
4943 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4944 // This needs to go at the end of the full GC.
4945 RegionResetter rs;
4946 heap_region_iterate(&rs);
4947 _free_regions = rs.getFreeRegionCount();
4948 // Tell the ZF thread it may have work to do.
4949 if (should_zf()) ZF_mon->notify_all();
4950 }
4952 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
4953 G1CollectedHeap* _g1;
4954 int _n;
4955 public:
4956 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4957 bool doHeapRegion(HeapRegion* r) {
4958 if (r->continuesHumongous()) return false;
4959 if (r->top() > r->bottom()) {
4960 // There are assertions in "set_zero_fill_needed()" below that
4961 // require top() == bottom(), so this is technically illegal.
4962 // We'll skirt the law here, by making that true temporarily.
4963 DEBUG_ONLY(HeapWord* save_top = r->top();
4964 r->set_top(r->bottom()));
4965 r->set_zero_fill_needed();
4966 DEBUG_ONLY(r->set_top(save_top));
4967 }
4968 return false;
4969 }
4970 };
4972 // Done at the start of full GC.
4973 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
4974 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4975 // This needs to go at the end of the full GC.
4976 UsedRegionsNeedZeroFillSetter rs;
4977 heap_region_iterate(&rs);
4978 }
4980 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
4981 _refine_cte_cl->set_concurrent(concurrent);
4982 }
4984 #ifndef PRODUCT
4986 class PrintHeapRegionClosure: public HeapRegionClosure {
4987 public:
4988 bool doHeapRegion(HeapRegion *r) {
4989 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
4990 if (r != NULL) {
4991 if (r->is_on_free_list())
4992 gclog_or_tty->print("Free ");
4993 if (r->is_young())
4994 gclog_or_tty->print("Young ");
4995 if (r->isHumongous())
4996 gclog_or_tty->print("Is Humongous ");
4997 r->print();
4998 }
4999 return false;
5000 }
5001 };
5003 class SortHeapRegionClosure : public HeapRegionClosure {
5004 size_t young_regions,free_regions, unclean_regions;
5005 size_t hum_regions, count;
5006 size_t unaccounted, cur_unclean, cur_alloc;
5007 size_t total_free;
5008 HeapRegion* cur;
5009 public:
5010 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5011 free_regions(0), unclean_regions(0),
5012 hum_regions(0),
5013 count(0), unaccounted(0),
5014 cur_alloc(0), total_free(0)
5015 {}
5016 bool doHeapRegion(HeapRegion *r) {
5017 count++;
5018 if (r->is_on_free_list()) free_regions++;
5019 else if (r->is_on_unclean_list()) unclean_regions++;
5020 else if (r->isHumongous()) hum_regions++;
5021 else if (r->is_young()) young_regions++;
5022 else if (r == cur) cur_alloc++;
5023 else unaccounted++;
5024 return false;
5025 }
5026 void print() {
5027 total_free = free_regions + unclean_regions;
5028 gclog_or_tty->print("%d regions\n", count);
5029 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5030 total_free, free_regions, unclean_regions);
5031 gclog_or_tty->print("%d humongous %d young\n",
5032 hum_regions, young_regions);
5033 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5034 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5035 }
5036 };
5038 void G1CollectedHeap::print_region_counts() {
5039 SortHeapRegionClosure sc(_cur_alloc_region);
5040 PrintHeapRegionClosure cl;
5041 heap_region_iterate(&cl);
5042 heap_region_iterate(&sc);
5043 sc.print();
5044 print_region_accounting_info();
5045 };
5047 bool G1CollectedHeap::regions_accounted_for() {
5048 // TODO: regions accounting for young/survivor/tenured
5049 return true;
5050 }
5052 bool G1CollectedHeap::print_region_accounting_info() {
5053 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5054 free_regions(),
5055 count_free_regions(), count_free_regions_list(),
5056 _free_region_list_size, _unclean_region_list.sz());
5057 gclog_or_tty->print_cr("cur_alloc: %d.",
5058 (_cur_alloc_region == NULL ? 0 : 1));
5059 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5061 // TODO: check regions accounting for young/survivor/tenured
5062 return true;
5063 }
5065 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5066 HeapRegion* hr = heap_region_containing(p);
5067 if (hr == NULL) {
5068 return is_in_permanent(p);
5069 } else {
5070 return hr->is_in(p);
5071 }
5072 }
5073 #endif // !PRODUCT
5075 void G1CollectedHeap::g1_unimplemented() {
5076 // Unimplemented();
5077 }