Tue, 04 Aug 2009 16:00:17 -0700
6819077: G1: first GC thread coming late into the GC.
Summary: The first worker thread is delayed when entering the GC because it clears the card count table that is used in identifying hot cards. Replace the card count table with a dynamically sized evicting hash table that includes an epoch based counter.
Reviewed-by: iveresov, tonyp
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectedHeap.cpp.incl"
28 // turn it on so that the contents of the young list (scan-only /
29 // to-be-collected) are printed at "strategic" points before / during
30 // / after the collection --- this is useful for debugging
31 #define SCAN_ONLY_VERBOSE 0
32 // CURRENT STATUS
33 // This file is under construction. Search for "FIXME".
35 // INVARIANTS/NOTES
36 //
37 // All allocation activity covered by the G1CollectedHeap interface is
38 // serialized by acquiring the HeapLock. This happens in
39 // mem_allocate_work, which all such allocation functions call.
40 // (Note that this does not apply to TLAB allocation, which is not part
41 // of this interface: it is done by clients of this interface.)
43 // Local to this file.
45 class RefineCardTableEntryClosure: public CardTableEntryClosure {
46 SuspendibleThreadSet* _sts;
47 G1RemSet* _g1rs;
48 ConcurrentG1Refine* _cg1r;
49 bool _concurrent;
50 public:
51 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
52 G1RemSet* g1rs,
53 ConcurrentG1Refine* cg1r) :
54 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
55 {}
56 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
57 _g1rs->concurrentRefineOneCard(card_ptr, worker_i);
58 if (_concurrent && _sts->should_yield()) {
59 // Caller will actually yield.
60 return false;
61 }
62 // Otherwise, we finished successfully; return true.
63 return true;
64 }
65 void set_concurrent(bool b) { _concurrent = b; }
66 };
69 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
70 int _calls;
71 G1CollectedHeap* _g1h;
72 CardTableModRefBS* _ctbs;
73 int _histo[256];
74 public:
75 ClearLoggedCardTableEntryClosure() :
76 _calls(0)
77 {
78 _g1h = G1CollectedHeap::heap();
79 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
80 for (int i = 0; i < 256; i++) _histo[i] = 0;
81 }
82 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
83 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
84 _calls++;
85 unsigned char* ujb = (unsigned char*)card_ptr;
86 int ind = (int)(*ujb);
87 _histo[ind]++;
88 *card_ptr = -1;
89 }
90 return true;
91 }
92 int calls() { return _calls; }
93 void print_histo() {
94 gclog_or_tty->print_cr("Card table value histogram:");
95 for (int i = 0; i < 256; i++) {
96 if (_histo[i] != 0) {
97 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
98 }
99 }
100 }
101 };
103 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
104 int _calls;
105 G1CollectedHeap* _g1h;
106 CardTableModRefBS* _ctbs;
107 public:
108 RedirtyLoggedCardTableEntryClosure() :
109 _calls(0)
110 {
111 _g1h = G1CollectedHeap::heap();
112 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
113 }
114 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
115 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
116 _calls++;
117 *card_ptr = 0;
118 }
119 return true;
120 }
121 int calls() { return _calls; }
122 };
124 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
125 public:
126 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 return true;
129 }
130 };
132 YoungList::YoungList(G1CollectedHeap* g1h)
133 : _g1h(g1h), _head(NULL),
134 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
135 _length(0), _scan_only_length(0),
136 _last_sampled_rs_lengths(0),
137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
138 {
139 guarantee( check_list_empty(false), "just making sure..." );
140 }
142 void YoungList::push_region(HeapRegion *hr) {
143 assert(!hr->is_young(), "should not already be young");
144 assert(hr->get_next_young_region() == NULL, "cause it should!");
146 hr->set_next_young_region(_head);
147 _head = hr;
149 hr->set_young();
150 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
151 ++_length;
152 }
154 void YoungList::add_survivor_region(HeapRegion* hr) {
155 assert(hr->is_survivor(), "should be flagged as survivor region");
156 assert(hr->get_next_young_region() == NULL, "cause it should!");
158 hr->set_next_young_region(_survivor_head);
159 if (_survivor_head == NULL) {
160 _survivor_tail = hr;
161 }
162 _survivor_head = hr;
164 ++_survivor_length;
165 }
167 HeapRegion* YoungList::pop_region() {
168 while (_head != NULL) {
169 assert( length() > 0, "list should not be empty" );
170 HeapRegion* ret = _head;
171 _head = ret->get_next_young_region();
172 ret->set_next_young_region(NULL);
173 --_length;
174 assert(ret->is_young(), "region should be very young");
176 // Replace 'Survivor' region type with 'Young'. So the region will
177 // be treated as a young region and will not be 'confused' with
178 // newly created survivor regions.
179 if (ret->is_survivor()) {
180 ret->set_young();
181 }
183 if (!ret->is_scan_only()) {
184 return ret;
185 }
187 // scan-only, we'll add it to the scan-only list
188 if (_scan_only_tail == NULL) {
189 guarantee( _scan_only_head == NULL, "invariant" );
191 _scan_only_head = ret;
192 _curr_scan_only = ret;
193 } else {
194 guarantee( _scan_only_head != NULL, "invariant" );
195 _scan_only_tail->set_next_young_region(ret);
196 }
197 guarantee( ret->get_next_young_region() == NULL, "invariant" );
198 _scan_only_tail = ret;
200 // no need to be tagged as scan-only any more
201 ret->set_young();
203 ++_scan_only_length;
204 }
205 assert( length() == 0, "list should be empty" );
206 return NULL;
207 }
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
226 empty_list(_scan_only_head);
227 _scan_only_head = NULL;
228 _scan_only_tail = NULL;
229 _scan_only_length = 0;
230 _curr_scan_only = NULL;
232 empty_list(_survivor_head);
233 _survivor_head = NULL;
234 _survivor_tail = NULL;
235 _survivor_length = 0;
237 _last_sampled_rs_lengths = 0;
239 assert(check_list_empty(false), "just making sure...");
240 }
242 bool YoungList::check_list_well_formed() {
243 bool ret = true;
245 size_t length = 0;
246 HeapRegion* curr = _head;
247 HeapRegion* last = NULL;
248 while (curr != NULL) {
249 if (!curr->is_young() || curr->is_scan_only()) {
250 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
251 "incorrectly tagged (%d, %d)",
252 curr->bottom(), curr->end(),
253 curr->is_young(), curr->is_scan_only());
254 ret = false;
255 }
256 ++length;
257 last = curr;
258 curr = curr->get_next_young_region();
259 }
260 ret = ret && (length == _length);
262 if (!ret) {
263 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
264 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
265 length, _length);
266 }
268 bool scan_only_ret = true;
269 length = 0;
270 curr = _scan_only_head;
271 last = NULL;
272 while (curr != NULL) {
273 if (!curr->is_young() || curr->is_scan_only()) {
274 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
275 "incorrectly tagged (%d, %d)",
276 curr->bottom(), curr->end(),
277 curr->is_young(), curr->is_scan_only());
278 scan_only_ret = false;
279 }
280 ++length;
281 last = curr;
282 curr = curr->get_next_young_region();
283 }
284 scan_only_ret = scan_only_ret && (length == _scan_only_length);
286 if ( (last != _scan_only_tail) ||
287 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
288 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
289 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
290 scan_only_ret = false;
291 }
293 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
294 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
295 scan_only_ret = false;
296 }
298 if (!scan_only_ret) {
299 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
300 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
301 length, _scan_only_length);
302 }
304 return ret && scan_only_ret;
305 }
307 bool YoungList::check_list_empty(bool ignore_scan_only_list,
308 bool check_sample) {
309 bool ret = true;
311 if (_length != 0) {
312 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
313 _length);
314 ret = false;
315 }
316 if (check_sample && _last_sampled_rs_lengths != 0) {
317 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
318 ret = false;
319 }
320 if (_head != NULL) {
321 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
322 ret = false;
323 }
324 if (!ret) {
325 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
326 }
328 if (ignore_scan_only_list)
329 return ret;
331 bool scan_only_ret = true;
332 if (_scan_only_length != 0) {
333 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
334 _scan_only_length);
335 scan_only_ret = false;
336 }
337 if (_scan_only_head != NULL) {
338 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
339 scan_only_ret = false;
340 }
341 if (_scan_only_tail != NULL) {
342 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
343 scan_only_ret = false;
344 }
345 if (!scan_only_ret) {
346 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
347 }
349 return ret && scan_only_ret;
350 }
352 void
353 YoungList::rs_length_sampling_init() {
354 _sampled_rs_lengths = 0;
355 _curr = _head;
356 }
358 bool
359 YoungList::rs_length_sampling_more() {
360 return _curr != NULL;
361 }
363 void
364 YoungList::rs_length_sampling_next() {
365 assert( _curr != NULL, "invariant" );
366 _sampled_rs_lengths += _curr->rem_set()->occupied();
367 _curr = _curr->get_next_young_region();
368 if (_curr == NULL) {
369 _last_sampled_rs_lengths = _sampled_rs_lengths;
370 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
371 }
372 }
374 void
375 YoungList::reset_auxilary_lists() {
376 // We could have just "moved" the scan-only list to the young list.
377 // However, the scan-only list is ordered according to the region
378 // age in descending order, so, by moving one entry at a time, we
379 // ensure that it is recreated in ascending order.
381 guarantee( is_empty(), "young list should be empty" );
382 assert(check_list_well_formed(), "young list should be well formed");
384 // Add survivor regions to SurvRateGroup.
385 _g1h->g1_policy()->note_start_adding_survivor_regions();
386 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
387 for (HeapRegion* curr = _survivor_head;
388 curr != NULL;
389 curr = curr->get_next_young_region()) {
390 _g1h->g1_policy()->set_region_survivors(curr);
391 }
392 _g1h->g1_policy()->note_stop_adding_survivor_regions();
394 if (_survivor_head != NULL) {
395 _head = _survivor_head;
396 _length = _survivor_length + _scan_only_length;
397 _survivor_tail->set_next_young_region(_scan_only_head);
398 } else {
399 _head = _scan_only_head;
400 _length = _scan_only_length;
401 }
403 for (HeapRegion* curr = _scan_only_head;
404 curr != NULL;
405 curr = curr->get_next_young_region()) {
406 curr->recalculate_age_in_surv_rate_group();
407 }
408 _scan_only_head = NULL;
409 _scan_only_tail = NULL;
410 _scan_only_length = 0;
411 _curr_scan_only = NULL;
413 _survivor_head = NULL;
414 _survivor_tail = NULL;
415 _survivor_length = 0;
416 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
418 assert(check_list_well_formed(), "young list should be well formed");
419 }
421 void YoungList::print() {
422 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
423 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
425 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
426 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
427 HeapRegion *curr = lists[list];
428 if (curr == NULL)
429 gclog_or_tty->print_cr(" empty");
430 while (curr != NULL) {
431 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
432 "age: %4d, y: %d, s-o: %d, surv: %d",
433 curr->bottom(), curr->end(),
434 curr->top(),
435 curr->prev_top_at_mark_start(),
436 curr->next_top_at_mark_start(),
437 curr->top_at_conc_mark_count(),
438 curr->age_in_surv_rate_group_cond(),
439 curr->is_young(),
440 curr->is_scan_only(),
441 curr->is_survivor());
442 curr = curr->get_next_young_region();
443 }
444 }
446 gclog_or_tty->print_cr("");
447 }
449 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
450 {
451 // Claim the right to put the region on the dirty cards region list
452 // by installing a self pointer.
453 HeapRegion* next = hr->get_next_dirty_cards_region();
454 if (next == NULL) {
455 HeapRegion* res = (HeapRegion*)
456 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
457 NULL);
458 if (res == NULL) {
459 HeapRegion* head;
460 do {
461 // Put the region to the dirty cards region list.
462 head = _dirty_cards_region_list;
463 next = (HeapRegion*)
464 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
465 if (next == head) {
466 assert(hr->get_next_dirty_cards_region() == hr,
467 "hr->get_next_dirty_cards_region() != hr");
468 if (next == NULL) {
469 // The last region in the list points to itself.
470 hr->set_next_dirty_cards_region(hr);
471 } else {
472 hr->set_next_dirty_cards_region(next);
473 }
474 }
475 } while (next != head);
476 }
477 }
478 }
480 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
481 {
482 HeapRegion* head;
483 HeapRegion* hr;
484 do {
485 head = _dirty_cards_region_list;
486 if (head == NULL) {
487 return NULL;
488 }
489 HeapRegion* new_head = head->get_next_dirty_cards_region();
490 if (head == new_head) {
491 // The last region.
492 new_head = NULL;
493 }
494 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
495 head);
496 } while (hr != head);
497 assert(hr != NULL, "invariant");
498 hr->set_next_dirty_cards_region(NULL);
499 return hr;
500 }
502 void G1CollectedHeap::stop_conc_gc_threads() {
503 _cg1r->stop();
504 _czft->stop();
505 _cmThread->stop();
506 }
509 void G1CollectedHeap::check_ct_logs_at_safepoint() {
510 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
511 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
513 // Count the dirty cards at the start.
514 CountNonCleanMemRegionClosure count1(this);
515 ct_bs->mod_card_iterate(&count1);
516 int orig_count = count1.n();
518 // First clear the logged cards.
519 ClearLoggedCardTableEntryClosure clear;
520 dcqs.set_closure(&clear);
521 dcqs.apply_closure_to_all_completed_buffers();
522 dcqs.iterate_closure_all_threads(false);
523 clear.print_histo();
525 // Now ensure that there's no dirty cards.
526 CountNonCleanMemRegionClosure count2(this);
527 ct_bs->mod_card_iterate(&count2);
528 if (count2.n() != 0) {
529 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
530 count2.n(), orig_count);
531 }
532 guarantee(count2.n() == 0, "Card table should be clean.");
534 RedirtyLoggedCardTableEntryClosure redirty;
535 JavaThread::dirty_card_queue_set().set_closure(&redirty);
536 dcqs.apply_closure_to_all_completed_buffers();
537 dcqs.iterate_closure_all_threads(false);
538 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
539 clear.calls(), orig_count);
540 guarantee(redirty.calls() == clear.calls(),
541 "Or else mechanism is broken.");
543 CountNonCleanMemRegionClosure count3(this);
544 ct_bs->mod_card_iterate(&count3);
545 if (count3.n() != orig_count) {
546 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
547 orig_count, count3.n());
548 guarantee(count3.n() >= orig_count, "Should have restored them all.");
549 }
551 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
552 }
554 // Private class members.
556 G1CollectedHeap* G1CollectedHeap::_g1h;
558 // Private methods.
560 // Finds a HeapRegion that can be used to allocate a given size of block.
563 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
564 bool do_expand,
565 bool zero_filled) {
566 ConcurrentZFThread::note_region_alloc();
567 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
568 if (res == NULL && do_expand) {
569 expand(word_size * HeapWordSize);
570 res = alloc_free_region_from_lists(zero_filled);
571 assert(res == NULL ||
572 (!res->isHumongous() &&
573 (!zero_filled ||
574 res->zero_fill_state() == HeapRegion::Allocated)),
575 "Alloc Regions must be zero filled (and non-H)");
576 }
577 if (res != NULL && res->is_empty()) _free_regions--;
578 assert(res == NULL ||
579 (!res->isHumongous() &&
580 (!zero_filled ||
581 res->zero_fill_state() == HeapRegion::Allocated)),
582 "Non-young alloc Regions must be zero filled (and non-H)");
584 if (G1PrintRegions) {
585 if (res != NULL) {
586 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
587 "top "PTR_FORMAT,
588 res->hrs_index(), res->bottom(), res->end(), res->top());
589 }
590 }
592 return res;
593 }
595 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
596 size_t word_size,
597 bool zero_filled) {
598 HeapRegion* alloc_region = NULL;
599 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
600 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
601 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
602 alloc_region->set_survivor();
603 }
604 ++_gc_alloc_region_counts[purpose];
605 } else {
606 g1_policy()->note_alloc_region_limit_reached(purpose);
607 }
608 return alloc_region;
609 }
611 // If could fit into free regions w/o expansion, try.
612 // Otherwise, if can expand, do so.
613 // Otherwise, if using ex regions might help, try with ex given back.
614 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
615 assert(regions_accounted_for(), "Region leakage!");
617 // We can't allocate H regions while cleanupComplete is running, since
618 // some of the regions we find to be empty might not yet be added to the
619 // unclean list. (If we're already at a safepoint, this call is
620 // unnecessary, not to mention wrong.)
621 if (!SafepointSynchronize::is_at_safepoint())
622 wait_for_cleanup_complete();
624 size_t num_regions =
625 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
627 // Special case if < one region???
629 // Remember the ft size.
630 size_t x_size = expansion_regions();
632 HeapWord* res = NULL;
633 bool eliminated_allocated_from_lists = false;
635 // Can the allocation potentially fit in the free regions?
636 if (free_regions() >= num_regions) {
637 res = _hrs->obj_allocate(word_size);
638 }
639 if (res == NULL) {
640 // Try expansion.
641 size_t fs = _hrs->free_suffix();
642 if (fs + x_size >= num_regions) {
643 expand((num_regions - fs) * HeapRegion::GrainBytes);
644 res = _hrs->obj_allocate(word_size);
645 assert(res != NULL, "This should have worked.");
646 } else {
647 // Expansion won't help. Are there enough free regions if we get rid
648 // of reservations?
649 size_t avail = free_regions();
650 if (avail >= num_regions) {
651 res = _hrs->obj_allocate(word_size);
652 if (res != NULL) {
653 remove_allocated_regions_from_lists();
654 eliminated_allocated_from_lists = true;
655 }
656 }
657 }
658 }
659 if (res != NULL) {
660 // Increment by the number of regions allocated.
661 // FIXME: Assumes regions all of size GrainBytes.
662 #ifndef PRODUCT
663 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
664 HeapRegion::GrainWords));
665 #endif
666 if (!eliminated_allocated_from_lists)
667 remove_allocated_regions_from_lists();
668 _summary_bytes_used += word_size * HeapWordSize;
669 _free_regions -= num_regions;
670 _num_humongous_regions += (int) num_regions;
671 }
672 assert(regions_accounted_for(), "Region Leakage");
673 return res;
674 }
676 HeapWord*
677 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
678 bool permit_collection_pause) {
679 HeapWord* res = NULL;
680 HeapRegion* allocated_young_region = NULL;
682 assert( SafepointSynchronize::is_at_safepoint() ||
683 Heap_lock->owned_by_self(), "pre condition of the call" );
685 if (isHumongous(word_size)) {
686 // Allocation of a humongous object can, in a sense, complete a
687 // partial region, if the previous alloc was also humongous, and
688 // caused the test below to succeed.
689 if (permit_collection_pause)
690 do_collection_pause_if_appropriate(word_size);
691 res = humongousObjAllocate(word_size);
692 assert(_cur_alloc_region == NULL
693 || !_cur_alloc_region->isHumongous(),
694 "Prevent a regression of this bug.");
696 } else {
697 // We may have concurrent cleanup working at the time. Wait for it
698 // to complete. In the future we would probably want to make the
699 // concurrent cleanup truly concurrent by decoupling it from the
700 // allocation.
701 if (!SafepointSynchronize::is_at_safepoint())
702 wait_for_cleanup_complete();
703 // If we do a collection pause, this will be reset to a non-NULL
704 // value. If we don't, nulling here ensures that we allocate a new
705 // region below.
706 if (_cur_alloc_region != NULL) {
707 // We're finished with the _cur_alloc_region.
708 _summary_bytes_used += _cur_alloc_region->used();
709 _cur_alloc_region = NULL;
710 }
711 assert(_cur_alloc_region == NULL, "Invariant.");
712 // Completion of a heap region is perhaps a good point at which to do
713 // a collection pause.
714 if (permit_collection_pause)
715 do_collection_pause_if_appropriate(word_size);
716 // Make sure we have an allocation region available.
717 if (_cur_alloc_region == NULL) {
718 if (!SafepointSynchronize::is_at_safepoint())
719 wait_for_cleanup_complete();
720 bool next_is_young = should_set_young_locked();
721 // If the next region is not young, make sure it's zero-filled.
722 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
723 if (_cur_alloc_region != NULL) {
724 _summary_bytes_used -= _cur_alloc_region->used();
725 if (next_is_young) {
726 set_region_short_lived_locked(_cur_alloc_region);
727 allocated_young_region = _cur_alloc_region;
728 }
729 }
730 }
731 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
732 "Prevent a regression of this bug.");
734 // Now retry the allocation.
735 if (_cur_alloc_region != NULL) {
736 res = _cur_alloc_region->allocate(word_size);
737 }
738 }
740 // NOTE: fails frequently in PRT
741 assert(regions_accounted_for(), "Region leakage!");
743 if (res != NULL) {
744 if (!SafepointSynchronize::is_at_safepoint()) {
745 assert( permit_collection_pause, "invariant" );
746 assert( Heap_lock->owned_by_self(), "invariant" );
747 Heap_lock->unlock();
748 }
750 if (allocated_young_region != NULL) {
751 HeapRegion* hr = allocated_young_region;
752 HeapWord* bottom = hr->bottom();
753 HeapWord* end = hr->end();
754 MemRegion mr(bottom, end);
755 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
756 }
757 }
759 assert( SafepointSynchronize::is_at_safepoint() ||
760 (res == NULL && Heap_lock->owned_by_self()) ||
761 (res != NULL && !Heap_lock->owned_by_self()),
762 "post condition of the call" );
764 return res;
765 }
767 HeapWord*
768 G1CollectedHeap::mem_allocate(size_t word_size,
769 bool is_noref,
770 bool is_tlab,
771 bool* gc_overhead_limit_was_exceeded) {
772 debug_only(check_for_valid_allocation_state());
773 assert(no_gc_in_progress(), "Allocation during gc not allowed");
774 HeapWord* result = NULL;
776 // Loop until the allocation is satisified,
777 // or unsatisfied after GC.
778 for (int try_count = 1; /* return or throw */; try_count += 1) {
779 int gc_count_before;
780 {
781 Heap_lock->lock();
782 result = attempt_allocation(word_size);
783 if (result != NULL) {
784 // attempt_allocation should have unlocked the heap lock
785 assert(is_in(result), "result not in heap");
786 return result;
787 }
788 // Read the gc count while the heap lock is held.
789 gc_count_before = SharedHeap::heap()->total_collections();
790 Heap_lock->unlock();
791 }
793 // Create the garbage collection operation...
794 VM_G1CollectForAllocation op(word_size,
795 gc_count_before);
797 // ...and get the VM thread to execute it.
798 VMThread::execute(&op);
799 if (op.prologue_succeeded()) {
800 result = op.result();
801 assert(result == NULL || is_in(result), "result not in heap");
802 return result;
803 }
805 // Give a warning if we seem to be looping forever.
806 if ((QueuedAllocationWarningCount > 0) &&
807 (try_count % QueuedAllocationWarningCount == 0)) {
808 warning("G1CollectedHeap::mem_allocate_work retries %d times",
809 try_count);
810 }
811 }
812 }
814 void G1CollectedHeap::abandon_cur_alloc_region() {
815 if (_cur_alloc_region != NULL) {
816 // We're finished with the _cur_alloc_region.
817 if (_cur_alloc_region->is_empty()) {
818 _free_regions++;
819 free_region(_cur_alloc_region);
820 } else {
821 _summary_bytes_used += _cur_alloc_region->used();
822 }
823 _cur_alloc_region = NULL;
824 }
825 }
827 void G1CollectedHeap::abandon_gc_alloc_regions() {
828 // first, make sure that the GC alloc region list is empty (it should!)
829 assert(_gc_alloc_region_list == NULL, "invariant");
830 release_gc_alloc_regions(true /* totally */);
831 }
833 class PostMCRemSetClearClosure: public HeapRegionClosure {
834 ModRefBarrierSet* _mr_bs;
835 public:
836 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
837 bool doHeapRegion(HeapRegion* r) {
838 r->reset_gc_time_stamp();
839 if (r->continuesHumongous())
840 return false;
841 HeapRegionRemSet* hrrs = r->rem_set();
842 if (hrrs != NULL) hrrs->clear();
843 // You might think here that we could clear just the cards
844 // corresponding to the used region. But no: if we leave a dirty card
845 // in a region we might allocate into, then it would prevent that card
846 // from being enqueued, and cause it to be missed.
847 // Re: the performance cost: we shouldn't be doing full GC anyway!
848 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
849 return false;
850 }
851 };
854 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
855 ModRefBarrierSet* _mr_bs;
856 public:
857 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
858 bool doHeapRegion(HeapRegion* r) {
859 if (r->continuesHumongous()) return false;
860 if (r->used_region().word_size() != 0) {
861 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
862 }
863 return false;
864 }
865 };
867 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
868 G1CollectedHeap* _g1h;
869 UpdateRSOopClosure _cl;
870 int _worker_i;
871 public:
872 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
873 _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
874 _worker_i(worker_i),
875 _g1h(g1)
876 { }
877 bool doHeapRegion(HeapRegion* r) {
878 if (!r->continuesHumongous()) {
879 _cl.set_from(r);
880 r->oop_iterate(&_cl);
881 }
882 return false;
883 }
884 };
886 class ParRebuildRSTask: public AbstractGangTask {
887 G1CollectedHeap* _g1;
888 public:
889 ParRebuildRSTask(G1CollectedHeap* g1)
890 : AbstractGangTask("ParRebuildRSTask"),
891 _g1(g1)
892 { }
894 void work(int i) {
895 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
896 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
897 HeapRegion::RebuildRSClaimValue);
898 }
899 };
901 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
902 size_t word_size) {
903 ResourceMark rm;
905 if (PrintHeapAtGC) {
906 Universe::print_heap_before_gc();
907 }
909 if (full && DisableExplicitGC) {
910 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
911 return;
912 }
914 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
915 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
917 if (GC_locker::is_active()) {
918 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
919 }
921 {
922 IsGCActiveMark x;
924 // Timing
925 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
926 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
927 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
929 double start = os::elapsedTime();
930 GCOverheadReporter::recordSTWStart(start);
931 g1_policy()->record_full_collection_start();
933 gc_prologue(true);
934 increment_total_collections(true /* full gc */);
936 size_t g1h_prev_used = used();
937 assert(used() == recalculate_used(), "Should be equal");
939 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
940 HandleMark hm; // Discard invalid handles created during verification
941 prepare_for_verify();
942 gclog_or_tty->print(" VerifyBeforeGC:");
943 Universe::verify(true);
944 }
945 assert(regions_accounted_for(), "Region leakage!");
947 COMPILER2_PRESENT(DerivedPointerTable::clear());
949 // We want to discover references, but not process them yet.
950 // This mode is disabled in
951 // instanceRefKlass::process_discovered_references if the
952 // generation does some collection work, or
953 // instanceRefKlass::enqueue_discovered_references if the
954 // generation returns without doing any work.
955 ref_processor()->disable_discovery();
956 ref_processor()->abandon_partial_discovery();
957 ref_processor()->verify_no_references_recorded();
959 // Abandon current iterations of concurrent marking and concurrent
960 // refinement, if any are in progress.
961 concurrent_mark()->abort();
963 // Make sure we'll choose a new allocation region afterwards.
964 abandon_cur_alloc_region();
965 abandon_gc_alloc_regions();
966 assert(_cur_alloc_region == NULL, "Invariant.");
967 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
968 tear_down_region_lists();
969 set_used_regions_to_need_zero_fill();
970 if (g1_policy()->in_young_gc_mode()) {
971 empty_young_list();
972 g1_policy()->set_full_young_gcs(true);
973 }
975 // Temporarily make reference _discovery_ single threaded (non-MT).
976 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
978 // Temporarily make refs discovery atomic
979 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
981 // Temporarily clear _is_alive_non_header
982 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
984 ref_processor()->enable_discovery();
985 ref_processor()->setup_policy(clear_all_soft_refs);
987 // Do collection work
988 {
989 HandleMark hm; // Discard invalid handles created during gc
990 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
991 }
992 // Because freeing humongous regions may have added some unclean
993 // regions, it is necessary to tear down again before rebuilding.
994 tear_down_region_lists();
995 rebuild_region_lists();
997 _summary_bytes_used = recalculate_used();
999 ref_processor()->enqueue_discovered_references();
1001 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1003 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1004 HandleMark hm; // Discard invalid handles created during verification
1005 gclog_or_tty->print(" VerifyAfterGC:");
1006 prepare_for_verify();
1007 Universe::verify(false);
1008 }
1009 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1011 reset_gc_time_stamp();
1012 // Since everything potentially moved, we will clear all remembered
1013 // sets, and clear all cards. Later we will rebuild remebered
1014 // sets. We will also reset the GC time stamps of the regions.
1015 PostMCRemSetClearClosure rs_clear(mr_bs());
1016 heap_region_iterate(&rs_clear);
1018 // Resize the heap if necessary.
1019 resize_if_necessary_after_full_collection(full ? 0 : word_size);
1021 if (_cg1r->use_cache()) {
1022 _cg1r->clear_and_record_card_counts();
1023 _cg1r->clear_hot_cache();
1024 }
1026 // Rebuild remembered sets of all regions.
1027 if (ParallelGCThreads > 0) {
1028 ParRebuildRSTask rebuild_rs_task(this);
1029 assert(check_heap_region_claim_values(
1030 HeapRegion::InitialClaimValue), "sanity check");
1031 set_par_threads(workers()->total_workers());
1032 workers()->run_task(&rebuild_rs_task);
1033 set_par_threads(0);
1034 assert(check_heap_region_claim_values(
1035 HeapRegion::RebuildRSClaimValue), "sanity check");
1036 reset_heap_region_claim_values();
1037 } else {
1038 RebuildRSOutOfRegionClosure rebuild_rs(this);
1039 heap_region_iterate(&rebuild_rs);
1040 }
1042 if (PrintGC) {
1043 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1044 }
1046 if (true) { // FIXME
1047 // Ask the permanent generation to adjust size for full collections
1048 perm()->compute_new_size();
1049 }
1051 double end = os::elapsedTime();
1052 GCOverheadReporter::recordSTWEnd(end);
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 }
1399 int n_queues = MAX2((int)ParallelGCThreads, 1);
1400 _task_queues = new RefToScanQueueSet(n_queues);
1402 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1403 assert(n_rem_sets > 0, "Invariant.");
1405 HeapRegionRemSetIterator** iter_arr =
1406 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1407 for (int i = 0; i < n_queues; i++) {
1408 iter_arr[i] = new HeapRegionRemSetIterator();
1409 }
1410 _rem_set_iterator = iter_arr;
1412 for (int i = 0; i < n_queues; i++) {
1413 RefToScanQueue* q = new RefToScanQueue();
1414 q->initialize();
1415 _task_queues->register_queue(i, q);
1416 }
1418 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1419 _gc_alloc_regions[ap] = NULL;
1420 _gc_alloc_region_counts[ap] = 0;
1421 _retained_gc_alloc_regions[ap] = NULL;
1422 // by default, we do not retain a GC alloc region for each ap;
1423 // we'll override this, when appropriate, below
1424 _retain_gc_alloc_region[ap] = false;
1425 }
1427 // We will try to remember the last half-full tenured region we
1428 // allocated to at the end of a collection so that we can re-use it
1429 // during the next collection.
1430 _retain_gc_alloc_region[GCAllocForTenured] = true;
1432 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1433 }
1435 jint G1CollectedHeap::initialize() {
1436 os::enable_vtime();
1438 // Necessary to satisfy locking discipline assertions.
1440 MutexLocker x(Heap_lock);
1442 // While there are no constraints in the GC code that HeapWordSize
1443 // be any particular value, there are multiple other areas in the
1444 // system which believe this to be true (e.g. oop->object_size in some
1445 // cases incorrectly returns the size in wordSize units rather than
1446 // HeapWordSize).
1447 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1449 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1450 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1452 // Ensure that the sizes are properly aligned.
1453 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1454 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1456 // We allocate this in any case, but only do no work if the command line
1457 // param is off.
1458 _cg1r = new ConcurrentG1Refine();
1460 // Reserve the maximum.
1461 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1462 // Includes the perm-gen.
1464 const size_t total_reserved = max_byte_size + pgs->max_size();
1465 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1467 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1468 HeapRegion::GrainBytes,
1469 false /*ism*/, addr);
1471 if (UseCompressedOops) {
1472 if (addr != NULL && !heap_rs.is_reserved()) {
1473 // Failed to reserve at specified address - the requested memory
1474 // region is taken already, for example, by 'java' launcher.
1475 // Try again to reserver heap higher.
1476 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1477 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1478 false /*ism*/, addr);
1479 if (addr != NULL && !heap_rs0.is_reserved()) {
1480 // Failed to reserve at specified address again - give up.
1481 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1482 assert(addr == NULL, "");
1483 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1484 false /*ism*/, addr);
1485 heap_rs = heap_rs1;
1486 } else {
1487 heap_rs = heap_rs0;
1488 }
1489 }
1490 }
1492 if (!heap_rs.is_reserved()) {
1493 vm_exit_during_initialization("Could not reserve enough space for object heap");
1494 return JNI_ENOMEM;
1495 }
1497 // It is important to do this in a way such that concurrent readers can't
1498 // temporarily think somethings in the heap. (I've actually seen this
1499 // happen in asserts: DLD.)
1500 _reserved.set_word_size(0);
1501 _reserved.set_start((HeapWord*)heap_rs.base());
1502 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1504 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1506 _num_humongous_regions = 0;
1508 // Create the gen rem set (and barrier set) for the entire reserved region.
1509 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1510 set_barrier_set(rem_set()->bs());
1511 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1512 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1513 } else {
1514 vm_exit_during_initialization("G1 requires a mod ref bs.");
1515 return JNI_ENOMEM;
1516 }
1518 // Also create a G1 rem set.
1519 if (G1UseHRIntoRS) {
1520 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1521 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1522 } else {
1523 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1524 return JNI_ENOMEM;
1525 }
1526 } else {
1527 _g1_rem_set = new StupidG1RemSet(this);
1528 }
1530 // Carve out the G1 part of the heap.
1532 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1533 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1534 g1_rs.size()/HeapWordSize);
1535 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1537 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1539 _g1_storage.initialize(g1_rs, 0);
1540 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1541 _g1_max_committed = _g1_committed;
1542 _hrs = new HeapRegionSeq(_expansion_regions);
1543 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1544 guarantee(_cur_alloc_region == NULL, "from constructor");
1546 // 6843694 - ensure that the maximum region index can fit
1547 // in the remembered set structures.
1548 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1549 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1551 const size_t cards_per_region = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift;
1552 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1553 guarantee(cards_per_region < max_cards_per_region, "too many cards per region");
1555 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1556 heap_word_size(init_byte_size));
1558 _g1h = this;
1560 // Create the ConcurrentMark data structure and thread.
1561 // (Must do this late, so that "max_regions" is defined.)
1562 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1563 _cmThread = _cm->cmThread();
1565 // ...and the concurrent zero-fill thread, if necessary.
1566 if (G1ConcZeroFill) {
1567 _czft = new ConcurrentZFThread();
1568 }
1570 // Initialize the from_card cache structure of HeapRegionRemSet.
1571 HeapRegionRemSet::init_heap(max_regions());
1573 // Now expand into the initial heap size.
1574 expand(init_byte_size);
1576 // Perform any initialization actions delegated to the policy.
1577 g1_policy()->init();
1579 g1_policy()->note_start_of_mark_thread();
1581 _refine_cte_cl =
1582 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1583 g1_rem_set(),
1584 concurrent_g1_refine());
1585 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1587 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1588 SATB_Q_FL_lock,
1589 0,
1590 Shared_SATB_Q_lock);
1592 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1593 DirtyCardQ_FL_lock,
1594 G1UpdateBufferQueueMaxLength,
1595 Shared_DirtyCardQ_lock);
1597 if (G1DeferredRSUpdate) {
1598 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1599 DirtyCardQ_FL_lock,
1600 0,
1601 Shared_DirtyCardQ_lock,
1602 &JavaThread::dirty_card_queue_set());
1603 }
1604 // In case we're keeping closure specialization stats, initialize those
1605 // counts and that mechanism.
1606 SpecializationStats::clear();
1608 _gc_alloc_region_list = NULL;
1610 // Do later initialization work for concurrent refinement.
1611 _cg1r->init();
1613 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1614 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1616 return JNI_OK;
1617 }
1619 void G1CollectedHeap::ref_processing_init() {
1620 SharedHeap::ref_processing_init();
1621 MemRegion mr = reserved_region();
1622 _ref_processor = ReferenceProcessor::create_ref_processor(
1623 mr, // span
1624 false, // Reference discovery is not atomic
1625 // (though it shouldn't matter here.)
1626 true, // mt_discovery
1627 NULL, // is alive closure: need to fill this in for efficiency
1628 ParallelGCThreads,
1629 ParallelRefProcEnabled,
1630 true); // Setting next fields of discovered
1631 // lists requires a barrier.
1632 }
1634 size_t G1CollectedHeap::capacity() const {
1635 return _g1_committed.byte_size();
1636 }
1638 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1639 int worker_i) {
1640 // Clean cards in the hot card cache
1641 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set());
1643 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1644 int n_completed_buffers = 0;
1645 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1646 n_completed_buffers++;
1647 }
1648 g1_policy()->record_update_rs_processed_buffers(worker_i,
1649 (double) n_completed_buffers);
1650 dcqs.clear_n_completed_buffers();
1651 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1652 }
1655 // Computes the sum of the storage used by the various regions.
1657 size_t G1CollectedHeap::used() const {
1658 assert(Heap_lock->owner() != NULL,
1659 "Should be owned on this thread's behalf.");
1660 size_t result = _summary_bytes_used;
1661 // Read only once in case it is set to NULL concurrently
1662 HeapRegion* hr = _cur_alloc_region;
1663 if (hr != NULL)
1664 result += hr->used();
1665 return result;
1666 }
1668 size_t G1CollectedHeap::used_unlocked() const {
1669 size_t result = _summary_bytes_used;
1670 return result;
1671 }
1673 class SumUsedClosure: public HeapRegionClosure {
1674 size_t _used;
1675 public:
1676 SumUsedClosure() : _used(0) {}
1677 bool doHeapRegion(HeapRegion* r) {
1678 if (!r->continuesHumongous()) {
1679 _used += r->used();
1680 }
1681 return false;
1682 }
1683 size_t result() { return _used; }
1684 };
1686 size_t G1CollectedHeap::recalculate_used() const {
1687 SumUsedClosure blk;
1688 _hrs->iterate(&blk);
1689 return blk.result();
1690 }
1692 #ifndef PRODUCT
1693 class SumUsedRegionsClosure: public HeapRegionClosure {
1694 size_t _num;
1695 public:
1696 SumUsedRegionsClosure() : _num(0) {}
1697 bool doHeapRegion(HeapRegion* r) {
1698 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1699 _num += 1;
1700 }
1701 return false;
1702 }
1703 size_t result() { return _num; }
1704 };
1706 size_t G1CollectedHeap::recalculate_used_regions() const {
1707 SumUsedRegionsClosure blk;
1708 _hrs->iterate(&blk);
1709 return blk.result();
1710 }
1711 #endif // PRODUCT
1713 size_t G1CollectedHeap::unsafe_max_alloc() {
1714 if (_free_regions > 0) return HeapRegion::GrainBytes;
1715 // otherwise, is there space in the current allocation region?
1717 // We need to store the current allocation region in a local variable
1718 // here. The problem is that this method doesn't take any locks and
1719 // there may be other threads which overwrite the current allocation
1720 // region field. attempt_allocation(), for example, sets it to NULL
1721 // and this can happen *after* the NULL check here but before the call
1722 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1723 // to be a problem in the optimized build, since the two loads of the
1724 // current allocation region field are optimized away.
1725 HeapRegion* car = _cur_alloc_region;
1727 // FIXME: should iterate over all regions?
1728 if (car == NULL) {
1729 return 0;
1730 }
1731 return car->free();
1732 }
1734 void G1CollectedHeap::collect(GCCause::Cause cause) {
1735 // The caller doesn't have the Heap_lock
1736 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1737 MutexLocker ml(Heap_lock);
1738 collect_locked(cause);
1739 }
1741 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1742 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1743 assert(Heap_lock->is_locked(), "Precondition#2");
1744 GCCauseSetter gcs(this, cause);
1745 switch (cause) {
1746 case GCCause::_heap_inspection:
1747 case GCCause::_heap_dump: {
1748 HandleMark hm;
1749 do_full_collection(false); // don't clear all soft refs
1750 break;
1751 }
1752 default: // XXX FIX ME
1753 ShouldNotReachHere(); // Unexpected use of this function
1754 }
1755 }
1758 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1759 // Don't want to do a GC until cleanup is completed.
1760 wait_for_cleanup_complete();
1762 // Read the GC count while holding the Heap_lock
1763 int gc_count_before = SharedHeap::heap()->total_collections();
1764 {
1765 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1766 VM_G1CollectFull op(gc_count_before, cause);
1767 VMThread::execute(&op);
1768 }
1769 }
1771 bool G1CollectedHeap::is_in(const void* p) const {
1772 if (_g1_committed.contains(p)) {
1773 HeapRegion* hr = _hrs->addr_to_region(p);
1774 return hr->is_in(p);
1775 } else {
1776 return _perm_gen->as_gen()->is_in(p);
1777 }
1778 }
1780 // Iteration functions.
1782 // Iterates an OopClosure over all ref-containing fields of objects
1783 // within a HeapRegion.
1785 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1786 MemRegion _mr;
1787 OopClosure* _cl;
1788 public:
1789 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1790 : _mr(mr), _cl(cl) {}
1791 bool doHeapRegion(HeapRegion* r) {
1792 if (! r->continuesHumongous()) {
1793 r->oop_iterate(_cl);
1794 }
1795 return false;
1796 }
1797 };
1799 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1800 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1801 _hrs->iterate(&blk);
1802 if (do_perm) {
1803 perm_gen()->oop_iterate(cl);
1804 }
1805 }
1807 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1808 IterateOopClosureRegionClosure blk(mr, cl);
1809 _hrs->iterate(&blk);
1810 if (do_perm) {
1811 perm_gen()->oop_iterate(cl);
1812 }
1813 }
1815 // Iterates an ObjectClosure over all objects within a HeapRegion.
1817 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1818 ObjectClosure* _cl;
1819 public:
1820 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1821 bool doHeapRegion(HeapRegion* r) {
1822 if (! r->continuesHumongous()) {
1823 r->object_iterate(_cl);
1824 }
1825 return false;
1826 }
1827 };
1829 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1830 IterateObjectClosureRegionClosure blk(cl);
1831 _hrs->iterate(&blk);
1832 if (do_perm) {
1833 perm_gen()->object_iterate(cl);
1834 }
1835 }
1837 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1838 // FIXME: is this right?
1839 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1840 }
1842 // Calls a SpaceClosure on a HeapRegion.
1844 class SpaceClosureRegionClosure: public HeapRegionClosure {
1845 SpaceClosure* _cl;
1846 public:
1847 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1848 bool doHeapRegion(HeapRegion* r) {
1849 _cl->do_space(r);
1850 return false;
1851 }
1852 };
1854 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1855 SpaceClosureRegionClosure blk(cl);
1856 _hrs->iterate(&blk);
1857 }
1859 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1860 _hrs->iterate(cl);
1861 }
1863 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1864 HeapRegionClosure* cl) {
1865 _hrs->iterate_from(r, cl);
1866 }
1868 void
1869 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1870 _hrs->iterate_from(idx, cl);
1871 }
1873 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1875 void
1876 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1877 int worker,
1878 jint claim_value) {
1879 const size_t regions = n_regions();
1880 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1881 // try to spread out the starting points of the workers
1882 const size_t start_index = regions / worker_num * (size_t) worker;
1884 // each worker will actually look at all regions
1885 for (size_t count = 0; count < regions; ++count) {
1886 const size_t index = (start_index + count) % regions;
1887 assert(0 <= index && index < regions, "sanity");
1888 HeapRegion* r = region_at(index);
1889 // we'll ignore "continues humongous" regions (we'll process them
1890 // when we come across their corresponding "start humongous"
1891 // region) and regions already claimed
1892 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1893 continue;
1894 }
1895 // OK, try to claim it
1896 if (r->claimHeapRegion(claim_value)) {
1897 // success!
1898 assert(!r->continuesHumongous(), "sanity");
1899 if (r->startsHumongous()) {
1900 // If the region is "starts humongous" we'll iterate over its
1901 // "continues humongous" first; in fact we'll do them
1902 // first. The order is important. In on case, calling the
1903 // closure on the "starts humongous" region might de-allocate
1904 // and clear all its "continues humongous" regions and, as a
1905 // result, we might end up processing them twice. So, we'll do
1906 // them first (notice: most closures will ignore them anyway) and
1907 // then we'll do the "starts humongous" region.
1908 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1909 HeapRegion* chr = region_at(ch_index);
1911 // if the region has already been claimed or it's not
1912 // "continues humongous" we're done
1913 if (chr->claim_value() == claim_value ||
1914 !chr->continuesHumongous()) {
1915 break;
1916 }
1918 // Noone should have claimed it directly. We can given
1919 // that we claimed its "starts humongous" region.
1920 assert(chr->claim_value() != claim_value, "sanity");
1921 assert(chr->humongous_start_region() == r, "sanity");
1923 if (chr->claimHeapRegion(claim_value)) {
1924 // we should always be able to claim it; noone else should
1925 // be trying to claim this region
1927 bool res2 = cl->doHeapRegion(chr);
1928 assert(!res2, "Should not abort");
1930 // Right now, this holds (i.e., no closure that actually
1931 // does something with "continues humongous" regions
1932 // clears them). We might have to weaken it in the future,
1933 // but let's leave these two asserts here for extra safety.
1934 assert(chr->continuesHumongous(), "should still be the case");
1935 assert(chr->humongous_start_region() == r, "sanity");
1936 } else {
1937 guarantee(false, "we should not reach here");
1938 }
1939 }
1940 }
1942 assert(!r->continuesHumongous(), "sanity");
1943 bool res = cl->doHeapRegion(r);
1944 assert(!res, "Should not abort");
1945 }
1946 }
1947 }
1949 class ResetClaimValuesClosure: public HeapRegionClosure {
1950 public:
1951 bool doHeapRegion(HeapRegion* r) {
1952 r->set_claim_value(HeapRegion::InitialClaimValue);
1953 return false;
1954 }
1955 };
1957 void
1958 G1CollectedHeap::reset_heap_region_claim_values() {
1959 ResetClaimValuesClosure blk;
1960 heap_region_iterate(&blk);
1961 }
1963 #ifdef ASSERT
1964 // This checks whether all regions in the heap have the correct claim
1965 // value. I also piggy-backed on this a check to ensure that the
1966 // humongous_start_region() information on "continues humongous"
1967 // regions is correct.
1969 class CheckClaimValuesClosure : public HeapRegionClosure {
1970 private:
1971 jint _claim_value;
1972 size_t _failures;
1973 HeapRegion* _sh_region;
1974 public:
1975 CheckClaimValuesClosure(jint claim_value) :
1976 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1977 bool doHeapRegion(HeapRegion* r) {
1978 if (r->claim_value() != _claim_value) {
1979 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1980 "claim value = %d, should be %d",
1981 r->bottom(), r->end(), r->claim_value(),
1982 _claim_value);
1983 ++_failures;
1984 }
1985 if (!r->isHumongous()) {
1986 _sh_region = NULL;
1987 } else if (r->startsHumongous()) {
1988 _sh_region = r;
1989 } else if (r->continuesHumongous()) {
1990 if (r->humongous_start_region() != _sh_region) {
1991 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1992 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1993 r->bottom(), r->end(),
1994 r->humongous_start_region(),
1995 _sh_region);
1996 ++_failures;
1997 }
1998 }
1999 return false;
2000 }
2001 size_t failures() {
2002 return _failures;
2003 }
2004 };
2006 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2007 CheckClaimValuesClosure cl(claim_value);
2008 heap_region_iterate(&cl);
2009 return cl.failures() == 0;
2010 }
2011 #endif // ASSERT
2013 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2014 HeapRegion* r = g1_policy()->collection_set();
2015 while (r != NULL) {
2016 HeapRegion* next = r->next_in_collection_set();
2017 if (cl->doHeapRegion(r)) {
2018 cl->incomplete();
2019 return;
2020 }
2021 r = next;
2022 }
2023 }
2025 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2026 HeapRegionClosure *cl) {
2027 assert(r->in_collection_set(),
2028 "Start region must be a member of the collection set.");
2029 HeapRegion* cur = r;
2030 while (cur != NULL) {
2031 HeapRegion* next = cur->next_in_collection_set();
2032 if (cl->doHeapRegion(cur) && false) {
2033 cl->incomplete();
2034 return;
2035 }
2036 cur = next;
2037 }
2038 cur = g1_policy()->collection_set();
2039 while (cur != r) {
2040 HeapRegion* next = cur->next_in_collection_set();
2041 if (cl->doHeapRegion(cur) && false) {
2042 cl->incomplete();
2043 return;
2044 }
2045 cur = next;
2046 }
2047 }
2049 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2050 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2051 }
2054 Space* G1CollectedHeap::space_containing(const void* addr) const {
2055 Space* res = heap_region_containing(addr);
2056 if (res == NULL)
2057 res = perm_gen()->space_containing(addr);
2058 return res;
2059 }
2061 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2062 Space* sp = space_containing(addr);
2063 if (sp != NULL) {
2064 return sp->block_start(addr);
2065 }
2066 return NULL;
2067 }
2069 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2070 Space* sp = space_containing(addr);
2071 assert(sp != NULL, "block_size of address outside of heap");
2072 return sp->block_size(addr);
2073 }
2075 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2076 Space* sp = space_containing(addr);
2077 return sp->block_is_obj(addr);
2078 }
2080 bool G1CollectedHeap::supports_tlab_allocation() const {
2081 return true;
2082 }
2084 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2085 return HeapRegion::GrainBytes;
2086 }
2088 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2089 // Return the remaining space in the cur alloc region, but not less than
2090 // the min TLAB size.
2091 // Also, no more than half the region size, since we can't allow tlabs to
2092 // grow big enough to accomodate humongous objects.
2094 // We need to story it locally, since it might change between when we
2095 // test for NULL and when we use it later.
2096 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2097 if (cur_alloc_space == NULL) {
2098 return HeapRegion::GrainBytes/2;
2099 } else {
2100 return MAX2(MIN2(cur_alloc_space->free(),
2101 (size_t)(HeapRegion::GrainBytes/2)),
2102 (size_t)MinTLABSize);
2103 }
2104 }
2106 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2107 bool dummy;
2108 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2109 }
2111 bool G1CollectedHeap::allocs_are_zero_filled() {
2112 return false;
2113 }
2115 size_t G1CollectedHeap::large_typearray_limit() {
2116 // FIXME
2117 return HeapRegion::GrainBytes/HeapWordSize;
2118 }
2120 size_t G1CollectedHeap::max_capacity() const {
2121 return _g1_committed.byte_size();
2122 }
2124 jlong G1CollectedHeap::millis_since_last_gc() {
2125 // assert(false, "NYI");
2126 return 0;
2127 }
2130 void G1CollectedHeap::prepare_for_verify() {
2131 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2132 ensure_parsability(false);
2133 }
2134 g1_rem_set()->prepare_for_verify();
2135 }
2137 class VerifyLivenessOopClosure: public OopClosure {
2138 G1CollectedHeap* g1h;
2139 public:
2140 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2141 g1h = _g1h;
2142 }
2143 void do_oop(narrowOop *p) { do_oop_work(p); }
2144 void do_oop( oop *p) { do_oop_work(p); }
2146 template <class T> void do_oop_work(T *p) {
2147 oop obj = oopDesc::load_decode_heap_oop(p);
2148 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2149 "Dead object referenced by a not dead object");
2150 }
2151 };
2153 class VerifyObjsInRegionClosure: public ObjectClosure {
2154 private:
2155 G1CollectedHeap* _g1h;
2156 size_t _live_bytes;
2157 HeapRegion *_hr;
2158 bool _use_prev_marking;
2159 public:
2160 // use_prev_marking == true -> use "prev" marking information,
2161 // use_prev_marking == false -> use "next" marking information
2162 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2163 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2164 _g1h = G1CollectedHeap::heap();
2165 }
2166 void do_object(oop o) {
2167 VerifyLivenessOopClosure isLive(_g1h);
2168 assert(o != NULL, "Huh?");
2169 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2170 o->oop_iterate(&isLive);
2171 if (!_hr->obj_allocated_since_prev_marking(o))
2172 _live_bytes += (o->size() * HeapWordSize);
2173 }
2174 }
2175 size_t live_bytes() { return _live_bytes; }
2176 };
2178 class PrintObjsInRegionClosure : public ObjectClosure {
2179 HeapRegion *_hr;
2180 G1CollectedHeap *_g1;
2181 public:
2182 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2183 _g1 = G1CollectedHeap::heap();
2184 };
2186 void do_object(oop o) {
2187 if (o != NULL) {
2188 HeapWord *start = (HeapWord *) o;
2189 size_t word_sz = o->size();
2190 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2191 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2192 (void*) o, word_sz,
2193 _g1->isMarkedPrev(o),
2194 _g1->isMarkedNext(o),
2195 _hr->obj_allocated_since_prev_marking(o));
2196 HeapWord *end = start + word_sz;
2197 HeapWord *cur;
2198 int *val;
2199 for (cur = start; cur < end; cur++) {
2200 val = (int *) cur;
2201 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2202 }
2203 }
2204 }
2205 };
2207 class VerifyRegionClosure: public HeapRegionClosure {
2208 private:
2209 bool _allow_dirty;
2210 bool _par;
2211 bool _use_prev_marking;
2212 public:
2213 // use_prev_marking == true -> use "prev" marking information,
2214 // use_prev_marking == false -> use "next" marking information
2215 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2216 : _allow_dirty(allow_dirty),
2217 _par(par),
2218 _use_prev_marking(use_prev_marking) {}
2220 bool doHeapRegion(HeapRegion* r) {
2221 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2222 "Should be unclaimed at verify points.");
2223 if (!r->continuesHumongous()) {
2224 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2225 r->verify(_allow_dirty, _use_prev_marking);
2226 r->object_iterate(¬_dead_yet_cl);
2227 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2228 "More live objects than counted in last complete marking.");
2229 }
2230 return false;
2231 }
2232 };
2234 class VerifyRootsClosure: public OopsInGenClosure {
2235 private:
2236 G1CollectedHeap* _g1h;
2237 bool _failures;
2238 bool _use_prev_marking;
2239 public:
2240 // use_prev_marking == true -> use "prev" marking information,
2241 // use_prev_marking == false -> use "next" marking information
2242 VerifyRootsClosure(bool use_prev_marking) :
2243 _g1h(G1CollectedHeap::heap()),
2244 _failures(false),
2245 _use_prev_marking(use_prev_marking) { }
2247 bool failures() { return _failures; }
2249 template <class T> void do_oop_nv(T* p) {
2250 T heap_oop = oopDesc::load_heap_oop(p);
2251 if (!oopDesc::is_null(heap_oop)) {
2252 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2253 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2254 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2255 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2256 obj->print_on(gclog_or_tty);
2257 _failures = true;
2258 }
2259 }
2260 }
2262 void do_oop(oop* p) { do_oop_nv(p); }
2263 void do_oop(narrowOop* p) { do_oop_nv(p); }
2264 };
2266 // This is the task used for parallel heap verification.
2268 class G1ParVerifyTask: public AbstractGangTask {
2269 private:
2270 G1CollectedHeap* _g1h;
2271 bool _allow_dirty;
2272 bool _use_prev_marking;
2274 public:
2275 // use_prev_marking == true -> use "prev" marking information,
2276 // use_prev_marking == false -> use "next" marking information
2277 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2278 bool use_prev_marking) :
2279 AbstractGangTask("Parallel verify task"),
2280 _g1h(g1h),
2281 _allow_dirty(allow_dirty),
2282 _use_prev_marking(use_prev_marking) { }
2284 void work(int worker_i) {
2285 HandleMark hm;
2286 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2287 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2288 HeapRegion::ParVerifyClaimValue);
2289 }
2290 };
2292 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2293 verify(allow_dirty, silent, /* use_prev_marking */ true);
2294 }
2296 void G1CollectedHeap::verify(bool allow_dirty,
2297 bool silent,
2298 bool use_prev_marking) {
2299 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2300 if (!silent) { gclog_or_tty->print("roots "); }
2301 VerifyRootsClosure rootsCl(use_prev_marking);
2302 process_strong_roots(false,
2303 SharedHeap::SO_AllClasses,
2304 &rootsCl,
2305 &rootsCl);
2306 rem_set()->invalidate(perm_gen()->used_region(), false);
2307 if (!silent) { gclog_or_tty->print("heapRegions "); }
2308 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2309 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2310 "sanity check");
2312 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2313 int n_workers = workers()->total_workers();
2314 set_par_threads(n_workers);
2315 workers()->run_task(&task);
2316 set_par_threads(0);
2318 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2319 "sanity check");
2321 reset_heap_region_claim_values();
2323 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2324 "sanity check");
2325 } else {
2326 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2327 _hrs->iterate(&blk);
2328 }
2329 if (!silent) gclog_or_tty->print("remset ");
2330 rem_set()->verify();
2331 guarantee(!rootsCl.failures(), "should not have had failures");
2332 } else {
2333 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2334 }
2335 }
2337 class PrintRegionClosure: public HeapRegionClosure {
2338 outputStream* _st;
2339 public:
2340 PrintRegionClosure(outputStream* st) : _st(st) {}
2341 bool doHeapRegion(HeapRegion* r) {
2342 r->print_on(_st);
2343 return false;
2344 }
2345 };
2347 void G1CollectedHeap::print() const { print_on(tty); }
2349 void G1CollectedHeap::print_on(outputStream* st) const {
2350 print_on(st, PrintHeapAtGCExtended);
2351 }
2353 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2354 st->print(" %-20s", "garbage-first heap");
2355 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2356 capacity()/K, used_unlocked()/K);
2357 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2358 _g1_storage.low_boundary(),
2359 _g1_storage.high(),
2360 _g1_storage.high_boundary());
2361 st->cr();
2362 st->print(" region size " SIZE_FORMAT "K, ",
2363 HeapRegion::GrainBytes/K);
2364 size_t young_regions = _young_list->length();
2365 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2366 young_regions, young_regions * HeapRegion::GrainBytes / K);
2367 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2368 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2369 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2370 st->cr();
2371 perm()->as_gen()->print_on(st);
2372 if (extended) {
2373 print_on_extended(st);
2374 }
2375 }
2377 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2378 PrintRegionClosure blk(st);
2379 _hrs->iterate(&blk);
2380 }
2382 class PrintOnThreadsClosure : public ThreadClosure {
2383 outputStream* _st;
2384 public:
2385 PrintOnThreadsClosure(outputStream* st) : _st(st) { }
2386 virtual void do_thread(Thread *t) {
2387 t->print_on(_st);
2388 }
2389 };
2391 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2392 if (ParallelGCThreads > 0) {
2393 workers()->print_worker_threads();
2394 }
2395 st->print("\"G1 concurrent mark GC Thread\" ");
2396 _cmThread->print();
2397 st->cr();
2398 st->print("\"G1 concurrent refinement GC Threads\" ");
2399 PrintOnThreadsClosure p(st);
2400 _cg1r->threads_do(&p);
2401 st->cr();
2402 st->print("\"G1 zero-fill GC Thread\" ");
2403 _czft->print_on(st);
2404 st->cr();
2405 }
2407 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2408 if (ParallelGCThreads > 0) {
2409 workers()->threads_do(tc);
2410 }
2411 tc->do_thread(_cmThread);
2412 _cg1r->threads_do(tc);
2413 tc->do_thread(_czft);
2414 }
2416 void G1CollectedHeap::print_tracing_info() const {
2417 // We'll overload this to mean "trace GC pause statistics."
2418 if (TraceGen0Time || TraceGen1Time) {
2419 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2420 // to that.
2421 g1_policy()->print_tracing_info();
2422 }
2423 if (G1SummarizeRSetStats) {
2424 g1_rem_set()->print_summary_info();
2425 }
2426 if (G1SummarizeConcurrentMark) {
2427 concurrent_mark()->print_summary_info();
2428 }
2429 if (G1SummarizeZFStats) {
2430 ConcurrentZFThread::print_summary_info();
2431 }
2432 g1_policy()->print_yg_surv_rate_info();
2434 GCOverheadReporter::printGCOverhead();
2436 SpecializationStats::print();
2437 }
2440 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2441 HeapRegion* hr = heap_region_containing(addr);
2442 if (hr == NULL) {
2443 return 0;
2444 } else {
2445 return 1;
2446 }
2447 }
2449 G1CollectedHeap* G1CollectedHeap::heap() {
2450 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2451 "not a garbage-first heap");
2452 return _g1h;
2453 }
2455 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2456 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2457 // Call allocation profiler
2458 AllocationProfiler::iterate_since_last_gc();
2459 // Fill TLAB's and such
2460 ensure_parsability(true);
2461 }
2463 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2464 // FIXME: what is this about?
2465 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2466 // is set.
2467 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2468 "derived pointer present"));
2469 }
2471 void G1CollectedHeap::do_collection_pause() {
2472 // Read the GC count while holding the Heap_lock
2473 // we need to do this _before_ wait_for_cleanup_complete(), to
2474 // ensure that we do not give up the heap lock and potentially
2475 // pick up the wrong count
2476 int gc_count_before = SharedHeap::heap()->total_collections();
2478 // Don't want to do a GC pause while cleanup is being completed!
2479 wait_for_cleanup_complete();
2481 g1_policy()->record_stop_world_start();
2482 {
2483 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2484 VM_G1IncCollectionPause op(gc_count_before);
2485 VMThread::execute(&op);
2486 }
2487 }
2489 void
2490 G1CollectedHeap::doConcurrentMark() {
2491 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2492 if (!_cmThread->in_progress()) {
2493 _cmThread->set_started();
2494 CGC_lock->notify();
2495 }
2496 }
2498 class VerifyMarkedObjsClosure: public ObjectClosure {
2499 G1CollectedHeap* _g1h;
2500 public:
2501 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2502 void do_object(oop obj) {
2503 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2504 "markandsweep mark should agree with concurrent deadness");
2505 }
2506 };
2508 void
2509 G1CollectedHeap::checkConcurrentMark() {
2510 VerifyMarkedObjsClosure verifycl(this);
2511 // MutexLockerEx x(getMarkBitMapLock(),
2512 // Mutex::_no_safepoint_check_flag);
2513 object_iterate(&verifycl, false);
2514 }
2516 void G1CollectedHeap::do_sync_mark() {
2517 _cm->checkpointRootsInitial();
2518 _cm->markFromRoots();
2519 _cm->checkpointRootsFinal(false);
2520 }
2522 // <NEW PREDICTION>
2524 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2525 bool young) {
2526 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2527 }
2529 void G1CollectedHeap::check_if_region_is_too_expensive(double
2530 predicted_time_ms) {
2531 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2532 }
2534 size_t G1CollectedHeap::pending_card_num() {
2535 size_t extra_cards = 0;
2536 JavaThread *curr = Threads::first();
2537 while (curr != NULL) {
2538 DirtyCardQueue& dcq = curr->dirty_card_queue();
2539 extra_cards += dcq.size();
2540 curr = curr->next();
2541 }
2542 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2543 size_t buffer_size = dcqs.buffer_size();
2544 size_t buffer_num = dcqs.completed_buffers_num();
2545 return buffer_size * buffer_num + extra_cards;
2546 }
2548 size_t G1CollectedHeap::max_pending_card_num() {
2549 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2550 size_t buffer_size = dcqs.buffer_size();
2551 size_t buffer_num = dcqs.completed_buffers_num();
2552 int thread_num = Threads::number_of_threads();
2553 return (buffer_num + thread_num) * buffer_size;
2554 }
2556 size_t G1CollectedHeap::cards_scanned() {
2557 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2558 return g1_rset->cardsScanned();
2559 }
2561 void
2562 G1CollectedHeap::setup_surviving_young_words() {
2563 guarantee( _surviving_young_words == NULL, "pre-condition" );
2564 size_t array_length = g1_policy()->young_cset_length();
2565 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2566 if (_surviving_young_words == NULL) {
2567 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2568 "Not enough space for young surv words summary.");
2569 }
2570 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2571 #ifdef ASSERT
2572 for (size_t i = 0; i < array_length; ++i) {
2573 assert( _surviving_young_words[i] == 0, "memset above" );
2574 }
2575 #endif // !ASSERT
2576 }
2578 void
2579 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2580 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2581 size_t array_length = g1_policy()->young_cset_length();
2582 for (size_t i = 0; i < array_length; ++i)
2583 _surviving_young_words[i] += surv_young_words[i];
2584 }
2586 void
2587 G1CollectedHeap::cleanup_surviving_young_words() {
2588 guarantee( _surviving_young_words != NULL, "pre-condition" );
2589 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2590 _surviving_young_words = NULL;
2591 }
2593 // </NEW PREDICTION>
2595 void
2596 G1CollectedHeap::do_collection_pause_at_safepoint() {
2597 if (PrintHeapAtGC) {
2598 Universe::print_heap_before_gc();
2599 }
2601 {
2602 char verbose_str[128];
2603 sprintf(verbose_str, "GC pause ");
2604 if (g1_policy()->in_young_gc_mode()) {
2605 if (g1_policy()->full_young_gcs())
2606 strcat(verbose_str, "(young)");
2607 else
2608 strcat(verbose_str, "(partial)");
2609 }
2610 if (g1_policy()->should_initiate_conc_mark())
2611 strcat(verbose_str, " (initial-mark)");
2613 GCCauseSetter x(this, GCCause::_g1_inc_collection_pause);
2615 // if PrintGCDetails is on, we'll print long statistics information
2616 // in the collector policy code, so let's not print this as the output
2617 // is messy if we do.
2618 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2619 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2620 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2622 ResourceMark rm;
2623 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2624 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2625 guarantee(!is_gc_active(), "collection is not reentrant");
2626 assert(regions_accounted_for(), "Region leakage!");
2628 increment_gc_time_stamp();
2630 if (g1_policy()->in_young_gc_mode()) {
2631 assert(check_young_list_well_formed(),
2632 "young list should be well formed");
2633 }
2635 if (GC_locker::is_active()) {
2636 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2637 }
2639 bool abandoned = false;
2640 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2641 IsGCActiveMark x;
2643 gc_prologue(false);
2644 increment_total_collections(false /* full gc */);
2646 #if G1_REM_SET_LOGGING
2647 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2648 print();
2649 #endif
2651 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2652 HandleMark hm; // Discard invalid handles created during verification
2653 prepare_for_verify();
2654 gclog_or_tty->print(" VerifyBeforeGC:");
2655 Universe::verify(false);
2656 }
2658 COMPILER2_PRESENT(DerivedPointerTable::clear());
2660 // We want to turn off ref discovery, if necessary, and turn it back on
2661 // on again later if we do. XXX Dubious: why is discovery disabled?
2662 bool was_enabled = ref_processor()->discovery_enabled();
2663 if (was_enabled) ref_processor()->disable_discovery();
2665 // Forget the current alloc region (we might even choose it to be part
2666 // of the collection set!).
2667 abandon_cur_alloc_region();
2669 // The elapsed time induced by the start time below deliberately elides
2670 // the possible verification above.
2671 double start_time_sec = os::elapsedTime();
2672 GCOverheadReporter::recordSTWStart(start_time_sec);
2673 size_t start_used_bytes = used();
2675 g1_policy()->record_collection_pause_start(start_time_sec,
2676 start_used_bytes);
2678 guarantee(_in_cset_fast_test == NULL, "invariant");
2679 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2680 _in_cset_fast_test_length = max_regions();
2681 _in_cset_fast_test_base =
2682 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2683 memset(_in_cset_fast_test_base, false,
2684 _in_cset_fast_test_length * sizeof(bool));
2685 // We're biasing _in_cset_fast_test to avoid subtracting the
2686 // beginning of the heap every time we want to index; basically
2687 // it's the same with what we do with the card table.
2688 _in_cset_fast_test = _in_cset_fast_test_base -
2689 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2691 #if SCAN_ONLY_VERBOSE
2692 _young_list->print();
2693 #endif // SCAN_ONLY_VERBOSE
2695 if (g1_policy()->should_initiate_conc_mark()) {
2696 concurrent_mark()->checkpointRootsInitialPre();
2697 }
2698 save_marks();
2700 // We must do this before any possible evacuation that should propagate
2701 // marks.
2702 if (mark_in_progress()) {
2703 double start_time_sec = os::elapsedTime();
2705 _cm->drainAllSATBBuffers();
2706 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2707 g1_policy()->record_satb_drain_time(finish_mark_ms);
2708 }
2709 // Record the number of elements currently on the mark stack, so we
2710 // only iterate over these. (Since evacuation may add to the mark
2711 // stack, doing more exposes race conditions.) If no mark is in
2712 // progress, this will be zero.
2713 _cm->set_oops_do_bound();
2715 assert(regions_accounted_for(), "Region leakage.");
2717 if (mark_in_progress())
2718 concurrent_mark()->newCSet();
2720 // Now choose the CS.
2721 g1_policy()->choose_collection_set();
2723 // We may abandon a pause if we find no region that will fit in the MMU
2724 // pause.
2725 bool abandoned = (g1_policy()->collection_set() == NULL);
2727 // Nothing to do if we were unable to choose a collection set.
2728 if (!abandoned) {
2729 #if G1_REM_SET_LOGGING
2730 gclog_or_tty->print_cr("\nAfter pause, heap:");
2731 print();
2732 #endif
2734 setup_surviving_young_words();
2736 // Set up the gc allocation regions.
2737 get_gc_alloc_regions();
2739 // Actually do the work...
2740 evacuate_collection_set();
2741 free_collection_set(g1_policy()->collection_set());
2742 g1_policy()->clear_collection_set();
2744 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2745 // this is more for peace of mind; we're nulling them here and
2746 // we're expecting them to be null at the beginning of the next GC
2747 _in_cset_fast_test = NULL;
2748 _in_cset_fast_test_base = NULL;
2750 release_gc_alloc_regions(false /* totally */);
2752 cleanup_surviving_young_words();
2754 if (g1_policy()->in_young_gc_mode()) {
2755 _young_list->reset_sampled_info();
2756 assert(check_young_list_empty(true),
2757 "young list should be empty");
2759 #if SCAN_ONLY_VERBOSE
2760 _young_list->print();
2761 #endif // SCAN_ONLY_VERBOSE
2763 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2764 _young_list->first_survivor_region(),
2765 _young_list->last_survivor_region());
2766 _young_list->reset_auxilary_lists();
2767 }
2768 } else {
2769 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2770 }
2772 if (evacuation_failed()) {
2773 _summary_bytes_used = recalculate_used();
2774 } else {
2775 // The "used" of the the collection set have already been subtracted
2776 // when they were freed. Add in the bytes evacuated.
2777 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2778 }
2780 if (g1_policy()->in_young_gc_mode() &&
2781 g1_policy()->should_initiate_conc_mark()) {
2782 concurrent_mark()->checkpointRootsInitialPost();
2783 set_marking_started();
2784 // CAUTION: after the doConcurrentMark() call below,
2785 // the concurrent marking thread(s) could be running
2786 // concurrently with us. Make sure that anything after
2787 // this point does not assume that we are the only GC thread
2788 // running. Note: of course, the actual marking work will
2789 // not start until the safepoint itself is released in
2790 // ConcurrentGCThread::safepoint_desynchronize().
2791 doConcurrentMark();
2792 }
2794 #if SCAN_ONLY_VERBOSE
2795 _young_list->print();
2796 #endif // SCAN_ONLY_VERBOSE
2798 double end_time_sec = os::elapsedTime();
2799 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2800 g1_policy()->record_pause_time_ms(pause_time_ms);
2801 GCOverheadReporter::recordSTWEnd(end_time_sec);
2802 g1_policy()->record_collection_pause_end(abandoned);
2804 assert(regions_accounted_for(), "Region leakage.");
2806 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2807 HandleMark hm; // Discard invalid handles created during verification
2808 gclog_or_tty->print(" VerifyAfterGC:");
2809 prepare_for_verify();
2810 Universe::verify(false);
2811 }
2813 if (was_enabled) ref_processor()->enable_discovery();
2815 {
2816 size_t expand_bytes = g1_policy()->expansion_amount();
2817 if (expand_bytes > 0) {
2818 size_t bytes_before = capacity();
2819 expand(expand_bytes);
2820 }
2821 }
2823 if (mark_in_progress()) {
2824 concurrent_mark()->update_g1_committed();
2825 }
2827 #ifdef TRACESPINNING
2828 ParallelTaskTerminator::print_termination_counts();
2829 #endif
2831 gc_epilogue(false);
2832 }
2834 assert(verify_region_lists(), "Bad region lists.");
2836 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2837 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2838 print_tracing_info();
2839 vm_exit(-1);
2840 }
2841 }
2843 if (PrintHeapAtGC) {
2844 Universe::print_heap_after_gc();
2845 }
2846 if (G1SummarizeRSetStats &&
2847 (G1SummarizeRSetStatsPeriod > 0) &&
2848 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
2849 g1_rem_set()->print_summary_info();
2850 }
2851 }
2853 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2854 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2855 // make sure we don't call set_gc_alloc_region() multiple times on
2856 // the same region
2857 assert(r == NULL || !r->is_gc_alloc_region(),
2858 "shouldn't already be a GC alloc region");
2859 HeapWord* original_top = NULL;
2860 if (r != NULL)
2861 original_top = r->top();
2863 // We will want to record the used space in r as being there before gc.
2864 // One we install it as a GC alloc region it's eligible for allocation.
2865 // So record it now and use it later.
2866 size_t r_used = 0;
2867 if (r != NULL) {
2868 r_used = r->used();
2870 if (ParallelGCThreads > 0) {
2871 // need to take the lock to guard against two threads calling
2872 // get_gc_alloc_region concurrently (very unlikely but...)
2873 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2874 r->save_marks();
2875 }
2876 }
2877 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2878 _gc_alloc_regions[purpose] = r;
2879 if (old_alloc_region != NULL) {
2880 // Replace aliases too.
2881 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2882 if (_gc_alloc_regions[ap] == old_alloc_region) {
2883 _gc_alloc_regions[ap] = r;
2884 }
2885 }
2886 }
2887 if (r != NULL) {
2888 push_gc_alloc_region(r);
2889 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2890 // We are using a region as a GC alloc region after it has been used
2891 // as a mutator allocation region during the current marking cycle.
2892 // The mutator-allocated objects are currently implicitly marked, but
2893 // when we move hr->next_top_at_mark_start() forward at the the end
2894 // of the GC pause, they won't be. We therefore mark all objects in
2895 // the "gap". We do this object-by-object, since marking densely
2896 // does not currently work right with marking bitmap iteration. This
2897 // means we rely on TLAB filling at the start of pauses, and no
2898 // "resuscitation" of filled TLAB's. If we want to do this, we need
2899 // to fix the marking bitmap iteration.
2900 HeapWord* curhw = r->next_top_at_mark_start();
2901 HeapWord* t = original_top;
2903 while (curhw < t) {
2904 oop cur = (oop)curhw;
2905 // We'll assume parallel for generality. This is rare code.
2906 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2907 curhw = curhw + cur->size();
2908 }
2909 assert(curhw == t, "Should have parsed correctly.");
2910 }
2911 if (G1PolicyVerbose > 1) {
2912 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2913 "for survivors:", r->bottom(), original_top, r->end());
2914 r->print();
2915 }
2916 g1_policy()->record_before_bytes(r_used);
2917 }
2918 }
2920 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2921 assert(Thread::current()->is_VM_thread() ||
2922 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2923 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2924 "Precondition.");
2925 hr->set_is_gc_alloc_region(true);
2926 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2927 _gc_alloc_region_list = hr;
2928 }
2930 #ifdef G1_DEBUG
2931 class FindGCAllocRegion: public HeapRegionClosure {
2932 public:
2933 bool doHeapRegion(HeapRegion* r) {
2934 if (r->is_gc_alloc_region()) {
2935 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2936 r->hrs_index(), r->bottom());
2937 }
2938 return false;
2939 }
2940 };
2941 #endif // G1_DEBUG
2943 void G1CollectedHeap::forget_alloc_region_list() {
2944 assert(Thread::current()->is_VM_thread(), "Precondition");
2945 while (_gc_alloc_region_list != NULL) {
2946 HeapRegion* r = _gc_alloc_region_list;
2947 assert(r->is_gc_alloc_region(), "Invariant.");
2948 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
2949 // newly allocated data in order to be able to apply deferred updates
2950 // before the GC is done for verification purposes (i.e to allow
2951 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
2952 // collection.
2953 r->ContiguousSpace::set_saved_mark();
2954 _gc_alloc_region_list = r->next_gc_alloc_region();
2955 r->set_next_gc_alloc_region(NULL);
2956 r->set_is_gc_alloc_region(false);
2957 if (r->is_survivor()) {
2958 if (r->is_empty()) {
2959 r->set_not_young();
2960 } else {
2961 _young_list->add_survivor_region(r);
2962 }
2963 }
2964 if (r->is_empty()) {
2965 ++_free_regions;
2966 }
2967 }
2968 #ifdef G1_DEBUG
2969 FindGCAllocRegion fa;
2970 heap_region_iterate(&fa);
2971 #endif // G1_DEBUG
2972 }
2975 bool G1CollectedHeap::check_gc_alloc_regions() {
2976 // TODO: allocation regions check
2977 return true;
2978 }
2980 void G1CollectedHeap::get_gc_alloc_regions() {
2981 // First, let's check that the GC alloc region list is empty (it should)
2982 assert(_gc_alloc_region_list == NULL, "invariant");
2984 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2985 assert(_gc_alloc_regions[ap] == NULL, "invariant");
2986 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
2988 // Create new GC alloc regions.
2989 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
2990 _retained_gc_alloc_regions[ap] = NULL;
2992 if (alloc_region != NULL) {
2993 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
2995 // let's make sure that the GC alloc region is not tagged as such
2996 // outside a GC operation
2997 assert(!alloc_region->is_gc_alloc_region(), "sanity");
2999 if (alloc_region->in_collection_set() ||
3000 alloc_region->top() == alloc_region->end() ||
3001 alloc_region->top() == alloc_region->bottom()) {
3002 // we will discard the current GC alloc region if it's in the
3003 // collection set (it can happen!), if it's already full (no
3004 // point in using it), or if it's empty (this means that it
3005 // was emptied during a cleanup and it should be on the free
3006 // list now).
3008 alloc_region = NULL;
3009 }
3010 }
3012 if (alloc_region == NULL) {
3013 // we will get a new GC alloc region
3014 alloc_region = newAllocRegionWithExpansion(ap, 0);
3015 } else {
3016 // the region was retained from the last collection
3017 ++_gc_alloc_region_counts[ap];
3018 }
3020 if (alloc_region != NULL) {
3021 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3022 set_gc_alloc_region(ap, alloc_region);
3023 }
3025 assert(_gc_alloc_regions[ap] == NULL ||
3026 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3027 "the GC alloc region should be tagged as such");
3028 assert(_gc_alloc_regions[ap] == NULL ||
3029 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3030 "the GC alloc region should be the same as the GC alloc list head");
3031 }
3032 // Set alternative regions for allocation purposes that have reached
3033 // their limit.
3034 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3035 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3036 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3037 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3038 }
3039 }
3040 assert(check_gc_alloc_regions(), "alloc regions messed up");
3041 }
3043 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3044 // We keep a separate list of all regions that have been alloc regions in
3045 // the current collection pause. Forget that now. This method will
3046 // untag the GC alloc regions and tear down the GC alloc region
3047 // list. It's desirable that no regions are tagged as GC alloc
3048 // outside GCs.
3049 forget_alloc_region_list();
3051 // The current alloc regions contain objs that have survived
3052 // collection. Make them no longer GC alloc regions.
3053 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3054 HeapRegion* r = _gc_alloc_regions[ap];
3055 _retained_gc_alloc_regions[ap] = NULL;
3056 _gc_alloc_region_counts[ap] = 0;
3058 if (r != NULL) {
3059 // we retain nothing on _gc_alloc_regions between GCs
3060 set_gc_alloc_region(ap, NULL);
3062 if (r->is_empty()) {
3063 // we didn't actually allocate anything in it; let's just put
3064 // it on the free list
3065 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3066 r->set_zero_fill_complete();
3067 put_free_region_on_list_locked(r);
3068 } else if (_retain_gc_alloc_region[ap] && !totally) {
3069 // retain it so that we can use it at the beginning of the next GC
3070 _retained_gc_alloc_regions[ap] = r;
3071 }
3072 }
3073 }
3074 }
3076 #ifndef PRODUCT
3077 // Useful for debugging
3079 void G1CollectedHeap::print_gc_alloc_regions() {
3080 gclog_or_tty->print_cr("GC alloc regions");
3081 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3082 HeapRegion* r = _gc_alloc_regions[ap];
3083 if (r == NULL) {
3084 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3085 } else {
3086 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3087 ap, r->bottom(), r->used());
3088 }
3089 }
3090 }
3091 #endif // PRODUCT
3093 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3094 _drain_in_progress = false;
3095 set_evac_failure_closure(cl);
3096 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3097 }
3099 void G1CollectedHeap::finalize_for_evac_failure() {
3100 assert(_evac_failure_scan_stack != NULL &&
3101 _evac_failure_scan_stack->length() == 0,
3102 "Postcondition");
3103 assert(!_drain_in_progress, "Postcondition");
3104 // Don't have to delete, since the scan stack is a resource object.
3105 _evac_failure_scan_stack = NULL;
3106 }
3110 // *** Sequential G1 Evacuation
3112 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3113 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3114 // let the caller handle alloc failure
3115 if (alloc_region == NULL) return NULL;
3116 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3117 "Either the object is humongous or the region isn't");
3118 HeapWord* block = alloc_region->allocate(word_size);
3119 if (block == NULL) {
3120 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3121 }
3122 return block;
3123 }
3125 class G1IsAliveClosure: public BoolObjectClosure {
3126 G1CollectedHeap* _g1;
3127 public:
3128 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3129 void do_object(oop p) { assert(false, "Do not call."); }
3130 bool do_object_b(oop p) {
3131 // It is reachable if it is outside the collection set, or is inside
3132 // and forwarded.
3134 #ifdef G1_DEBUG
3135 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3136 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3137 !_g1->obj_in_cs(p) || p->is_forwarded());
3138 #endif // G1_DEBUG
3140 return !_g1->obj_in_cs(p) || p->is_forwarded();
3141 }
3142 };
3144 class G1KeepAliveClosure: public OopClosure {
3145 G1CollectedHeap* _g1;
3146 public:
3147 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3148 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3149 void do_oop( oop* p) {
3150 oop obj = *p;
3151 #ifdef G1_DEBUG
3152 if (PrintGC && Verbose) {
3153 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3154 p, (void*) obj, (void*) *p);
3155 }
3156 #endif // G1_DEBUG
3158 if (_g1->obj_in_cs(obj)) {
3159 assert( obj->is_forwarded(), "invariant" );
3160 *p = obj->forwardee();
3161 #ifdef G1_DEBUG
3162 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3163 (void*) obj, (void*) *p);
3164 #endif // G1_DEBUG
3165 }
3166 }
3167 };
3169 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3170 private:
3171 G1CollectedHeap* _g1;
3172 G1RemSet* _g1_rem_set;
3173 public:
3174 UpdateRSetImmediate(G1CollectedHeap* g1) :
3175 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3177 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3178 virtual void do_oop( oop* p) { do_oop_work(p); }
3179 template <class T> void do_oop_work(T* p) {
3180 assert(_from->is_in_reserved(p), "paranoia");
3181 T heap_oop = oopDesc::load_heap_oop(p);
3182 if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
3183 _g1_rem_set->par_write_ref(_from, p, 0);
3184 }
3185 }
3186 };
3188 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3189 private:
3190 G1CollectedHeap* _g1;
3191 DirtyCardQueue *_dcq;
3192 CardTableModRefBS* _ct_bs;
3194 public:
3195 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3196 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3198 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3199 virtual void do_oop( oop* p) { do_oop_work(p); }
3200 template <class T> void do_oop_work(T* p) {
3201 assert(_from->is_in_reserved(p), "paranoia");
3202 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3203 !_from->is_survivor()) {
3204 size_t card_index = _ct_bs->index_for(p);
3205 if (_ct_bs->mark_card_deferred(card_index)) {
3206 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3207 }
3208 }
3209 }
3210 };
3214 class RemoveSelfPointerClosure: public ObjectClosure {
3215 private:
3216 G1CollectedHeap* _g1;
3217 ConcurrentMark* _cm;
3218 HeapRegion* _hr;
3219 size_t _prev_marked_bytes;
3220 size_t _next_marked_bytes;
3221 OopsInHeapRegionClosure *_cl;
3222 public:
3223 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3224 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3225 _next_marked_bytes(0), _cl(cl) {}
3227 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3228 size_t next_marked_bytes() { return _next_marked_bytes; }
3230 // The original idea here was to coalesce evacuated and dead objects.
3231 // However that caused complications with the block offset table (BOT).
3232 // In particular if there were two TLABs, one of them partially refined.
3233 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3234 // The BOT entries of the unrefined part of TLAB_2 point to the start
3235 // of TLAB_2. If the last object of the TLAB_1 and the first object
3236 // of TLAB_2 are coalesced, then the cards of the unrefined part
3237 // would point into middle of the filler object.
3238 //
3239 // The current approach is to not coalesce and leave the BOT contents intact.
3240 void do_object(oop obj) {
3241 if (obj->is_forwarded() && obj->forwardee() == obj) {
3242 // The object failed to move.
3243 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3244 _cm->markPrev(obj);
3245 assert(_cm->isPrevMarked(obj), "Should be marked!");
3246 _prev_marked_bytes += (obj->size() * HeapWordSize);
3247 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3248 _cm->markAndGrayObjectIfNecessary(obj);
3249 }
3250 obj->set_mark(markOopDesc::prototype());
3251 // While we were processing RSet buffers during the
3252 // collection, we actually didn't scan any cards on the
3253 // collection set, since we didn't want to update remebered
3254 // sets with entries that point into the collection set, given
3255 // that live objects fromthe collection set are about to move
3256 // and such entries will be stale very soon. This change also
3257 // dealt with a reliability issue which involved scanning a
3258 // card in the collection set and coming across an array that
3259 // was being chunked and looking malformed. The problem is
3260 // that, if evacuation fails, we might have remembered set
3261 // entries missing given that we skipped cards on the
3262 // collection set. So, we'll recreate such entries now.
3263 obj->oop_iterate(_cl);
3264 assert(_cm->isPrevMarked(obj), "Should be marked!");
3265 } else {
3266 // The object has been either evacuated or is dead. Fill it with a
3267 // dummy object.
3268 MemRegion mr((HeapWord*)obj, obj->size());
3269 CollectedHeap::fill_with_object(mr);
3270 _cm->clearRangeBothMaps(mr);
3271 }
3272 }
3273 };
3275 void G1CollectedHeap::remove_self_forwarding_pointers() {
3276 UpdateRSetImmediate immediate_update(_g1h);
3277 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3278 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3279 OopsInHeapRegionClosure *cl;
3280 if (G1DeferredRSUpdate) {
3281 cl = &deferred_update;
3282 } else {
3283 cl = &immediate_update;
3284 }
3285 HeapRegion* cur = g1_policy()->collection_set();
3286 while (cur != NULL) {
3287 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3289 RemoveSelfPointerClosure rspc(_g1h, cl);
3290 if (cur->evacuation_failed()) {
3291 assert(cur->in_collection_set(), "bad CS");
3292 cl->set_region(cur);
3293 cur->object_iterate(&rspc);
3295 // A number of manipulations to make the TAMS be the current top,
3296 // and the marked bytes be the ones observed in the iteration.
3297 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3298 // The comments below are the postconditions achieved by the
3299 // calls. Note especially the last such condition, which says that
3300 // the count of marked bytes has been properly restored.
3301 cur->note_start_of_marking(false);
3302 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3303 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3304 // _next_marked_bytes == prev_marked_bytes.
3305 cur->note_end_of_marking();
3306 // _prev_top_at_mark_start == top(),
3307 // _prev_marked_bytes == prev_marked_bytes
3308 }
3309 // If there is no mark in progress, we modified the _next variables
3310 // above needlessly, but harmlessly.
3311 if (_g1h->mark_in_progress()) {
3312 cur->note_start_of_marking(false);
3313 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3314 // _next_marked_bytes == next_marked_bytes.
3315 }
3317 // Now make sure the region has the right index in the sorted array.
3318 g1_policy()->note_change_in_marked_bytes(cur);
3319 }
3320 cur = cur->next_in_collection_set();
3321 }
3322 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3324 // Now restore saved marks, if any.
3325 if (_objs_with_preserved_marks != NULL) {
3326 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3327 assert(_objs_with_preserved_marks->length() ==
3328 _preserved_marks_of_objs->length(), "Both or none.");
3329 guarantee(_objs_with_preserved_marks->length() ==
3330 _preserved_marks_of_objs->length(), "Both or none.");
3331 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3332 oop obj = _objs_with_preserved_marks->at(i);
3333 markOop m = _preserved_marks_of_objs->at(i);
3334 obj->set_mark(m);
3335 }
3336 // Delete the preserved marks growable arrays (allocated on the C heap).
3337 delete _objs_with_preserved_marks;
3338 delete _preserved_marks_of_objs;
3339 _objs_with_preserved_marks = NULL;
3340 _preserved_marks_of_objs = NULL;
3341 }
3342 }
3344 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3345 _evac_failure_scan_stack->push(obj);
3346 }
3348 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3349 assert(_evac_failure_scan_stack != NULL, "precondition");
3351 while (_evac_failure_scan_stack->length() > 0) {
3352 oop obj = _evac_failure_scan_stack->pop();
3353 _evac_failure_closure->set_region(heap_region_containing(obj));
3354 obj->oop_iterate_backwards(_evac_failure_closure);
3355 }
3356 }
3358 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3359 markOop m = old->mark();
3360 // forward to self
3361 assert(!old->is_forwarded(), "precondition");
3363 old->forward_to(old);
3364 handle_evacuation_failure_common(old, m);
3365 }
3367 oop
3368 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3369 oop old) {
3370 markOop m = old->mark();
3371 oop forward_ptr = old->forward_to_atomic(old);
3372 if (forward_ptr == NULL) {
3373 // Forward-to-self succeeded.
3374 if (_evac_failure_closure != cl) {
3375 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3376 assert(!_drain_in_progress,
3377 "Should only be true while someone holds the lock.");
3378 // Set the global evac-failure closure to the current thread's.
3379 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3380 set_evac_failure_closure(cl);
3381 // Now do the common part.
3382 handle_evacuation_failure_common(old, m);
3383 // Reset to NULL.
3384 set_evac_failure_closure(NULL);
3385 } else {
3386 // The lock is already held, and this is recursive.
3387 assert(_drain_in_progress, "This should only be the recursive case.");
3388 handle_evacuation_failure_common(old, m);
3389 }
3390 return old;
3391 } else {
3392 // Someone else had a place to copy it.
3393 return forward_ptr;
3394 }
3395 }
3397 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3398 set_evacuation_failed(true);
3400 preserve_mark_if_necessary(old, m);
3402 HeapRegion* r = heap_region_containing(old);
3403 if (!r->evacuation_failed()) {
3404 r->set_evacuation_failed(true);
3405 if (G1PrintRegions) {
3406 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3407 "["PTR_FORMAT","PTR_FORMAT")\n",
3408 r, r->bottom(), r->end());
3409 }
3410 }
3412 push_on_evac_failure_scan_stack(old);
3414 if (!_drain_in_progress) {
3415 // prevent recursion in copy_to_survivor_space()
3416 _drain_in_progress = true;
3417 drain_evac_failure_scan_stack();
3418 _drain_in_progress = false;
3419 }
3420 }
3422 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3423 if (m != markOopDesc::prototype()) {
3424 if (_objs_with_preserved_marks == NULL) {
3425 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3426 _objs_with_preserved_marks =
3427 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3428 _preserved_marks_of_objs =
3429 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3430 }
3431 _objs_with_preserved_marks->push(obj);
3432 _preserved_marks_of_objs->push(m);
3433 }
3434 }
3436 // *** Parallel G1 Evacuation
3438 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3439 size_t word_size) {
3440 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3441 // let the caller handle alloc failure
3442 if (alloc_region == NULL) return NULL;
3444 HeapWord* block = alloc_region->par_allocate(word_size);
3445 if (block == NULL) {
3446 MutexLockerEx x(par_alloc_during_gc_lock(),
3447 Mutex::_no_safepoint_check_flag);
3448 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3449 }
3450 return block;
3451 }
3453 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3454 bool par) {
3455 // Another thread might have obtained alloc_region for the given
3456 // purpose, and might be attempting to allocate in it, and might
3457 // succeed. Therefore, we can't do the "finalization" stuff on the
3458 // region below until we're sure the last allocation has happened.
3459 // We ensure this by allocating the remaining space with a garbage
3460 // object.
3461 if (par) par_allocate_remaining_space(alloc_region);
3462 // Now we can do the post-GC stuff on the region.
3463 alloc_region->note_end_of_copying();
3464 g1_policy()->record_after_bytes(alloc_region->used());
3465 }
3467 HeapWord*
3468 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3469 HeapRegion* alloc_region,
3470 bool par,
3471 size_t word_size) {
3472 HeapWord* block = NULL;
3473 // In the parallel case, a previous thread to obtain the lock may have
3474 // already assigned a new gc_alloc_region.
3475 if (alloc_region != _gc_alloc_regions[purpose]) {
3476 assert(par, "But should only happen in parallel case.");
3477 alloc_region = _gc_alloc_regions[purpose];
3478 if (alloc_region == NULL) return NULL;
3479 block = alloc_region->par_allocate(word_size);
3480 if (block != NULL) return block;
3481 // Otherwise, continue; this new region is empty, too.
3482 }
3483 assert(alloc_region != NULL, "We better have an allocation region");
3484 retire_alloc_region(alloc_region, par);
3486 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3487 // Cannot allocate more regions for the given purpose.
3488 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3489 // Is there an alternative?
3490 if (purpose != alt_purpose) {
3491 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3492 // Has not the alternative region been aliased?
3493 if (alloc_region != alt_region && alt_region != NULL) {
3494 // Try to allocate in the alternative region.
3495 if (par) {
3496 block = alt_region->par_allocate(word_size);
3497 } else {
3498 block = alt_region->allocate(word_size);
3499 }
3500 // Make an alias.
3501 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3502 if (block != NULL) {
3503 return block;
3504 }
3505 retire_alloc_region(alt_region, par);
3506 }
3507 // Both the allocation region and the alternative one are full
3508 // and aliased, replace them with a new allocation region.
3509 purpose = alt_purpose;
3510 } else {
3511 set_gc_alloc_region(purpose, NULL);
3512 return NULL;
3513 }
3514 }
3516 // Now allocate a new region for allocation.
3517 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3519 // let the caller handle alloc failure
3520 if (alloc_region != NULL) {
3522 assert(check_gc_alloc_regions(), "alloc regions messed up");
3523 assert(alloc_region->saved_mark_at_top(),
3524 "Mark should have been saved already.");
3525 // We used to assert that the region was zero-filled here, but no
3526 // longer.
3528 // This must be done last: once it's installed, other regions may
3529 // allocate in it (without holding the lock.)
3530 set_gc_alloc_region(purpose, alloc_region);
3532 if (par) {
3533 block = alloc_region->par_allocate(word_size);
3534 } else {
3535 block = alloc_region->allocate(word_size);
3536 }
3537 // Caller handles alloc failure.
3538 } else {
3539 // This sets other apis using the same old alloc region to NULL, also.
3540 set_gc_alloc_region(purpose, NULL);
3541 }
3542 return block; // May be NULL.
3543 }
3545 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3546 HeapWord* block = NULL;
3547 size_t free_words;
3548 do {
3549 free_words = r->free()/HeapWordSize;
3550 // If there's too little space, no one can allocate, so we're done.
3551 if (free_words < (size_t)oopDesc::header_size()) return;
3552 // Otherwise, try to claim it.
3553 block = r->par_allocate(free_words);
3554 } while (block == NULL);
3555 fill_with_object(block, free_words);
3556 }
3558 #ifndef PRODUCT
3559 bool GCLabBitMapClosure::do_bit(size_t offset) {
3560 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3561 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3562 return true;
3563 }
3564 #endif // PRODUCT
3566 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3567 : _g1h(g1h),
3568 _refs(g1h->task_queue(queue_num)),
3569 _dcq(&g1h->dirty_card_queue_set()),
3570 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3571 _g1_rem(g1h->g1_rem_set()),
3572 _hash_seed(17), _queue_num(queue_num),
3573 _term_attempts(0),
3574 _age_table(false),
3575 #if G1_DETAILED_STATS
3576 _pushes(0), _pops(0), _steals(0),
3577 _steal_attempts(0), _overflow_pushes(0),
3578 #endif
3579 _strong_roots_time(0), _term_time(0),
3580 _alloc_buffer_waste(0), _undo_waste(0)
3581 {
3582 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3583 // we "sacrifice" entry 0 to keep track of surviving bytes for
3584 // non-young regions (where the age is -1)
3585 // We also add a few elements at the beginning and at the end in
3586 // an attempt to eliminate cache contention
3587 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3588 size_t array_length = PADDING_ELEM_NUM +
3589 real_length +
3590 PADDING_ELEM_NUM;
3591 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3592 if (_surviving_young_words_base == NULL)
3593 vm_exit_out_of_memory(array_length * sizeof(size_t),
3594 "Not enough space for young surv histo.");
3595 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3596 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3598 _overflowed_refs = new OverflowQueue(10);
3600 _start = os::elapsedTime();
3601 }
3603 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3604 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3605 _par_scan_state(par_scan_state) { }
3607 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3608 // This is called _after_ do_oop_work has been called, hence after
3609 // the object has been relocated to its new location and *p points
3610 // to its new location.
3612 T heap_oop = oopDesc::load_heap_oop(p);
3613 if (!oopDesc::is_null(heap_oop)) {
3614 oop obj = oopDesc::decode_heap_oop(heap_oop);
3615 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3616 "shouldn't still be in the CSet if evacuation didn't fail.");
3617 HeapWord* addr = (HeapWord*)obj;
3618 if (_g1->is_in_g1_reserved(addr))
3619 _cm->grayRoot(oop(addr));
3620 }
3621 }
3623 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3624 size_t word_sz = old->size();
3625 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3626 // +1 to make the -1 indexes valid...
3627 int young_index = from_region->young_index_in_cset()+1;
3628 assert( (from_region->is_young() && young_index > 0) ||
3629 (!from_region->is_young() && young_index == 0), "invariant" );
3630 G1CollectorPolicy* g1p = _g1->g1_policy();
3631 markOop m = old->mark();
3632 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3633 : m->age();
3634 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3635 word_sz);
3636 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3637 oop obj = oop(obj_ptr);
3639 if (obj_ptr == NULL) {
3640 // This will either forward-to-self, or detect that someone else has
3641 // installed a forwarding pointer.
3642 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3643 return _g1->handle_evacuation_failure_par(cl, old);
3644 }
3646 // We're going to allocate linearly, so might as well prefetch ahead.
3647 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3649 oop forward_ptr = old->forward_to_atomic(obj);
3650 if (forward_ptr == NULL) {
3651 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3652 if (g1p->track_object_age(alloc_purpose)) {
3653 // We could simply do obj->incr_age(). However, this causes a
3654 // performance issue. obj->incr_age() will first check whether
3655 // the object has a displaced mark by checking its mark word;
3656 // getting the mark word from the new location of the object
3657 // stalls. So, given that we already have the mark word and we
3658 // are about to install it anyway, it's better to increase the
3659 // age on the mark word, when the object does not have a
3660 // displaced mark word. We're not expecting many objects to have
3661 // a displaced marked word, so that case is not optimized
3662 // further (it could be...) and we simply call obj->incr_age().
3664 if (m->has_displaced_mark_helper()) {
3665 // in this case, we have to install the mark word first,
3666 // otherwise obj looks to be forwarded (the old mark word,
3667 // which contains the forward pointer, was copied)
3668 obj->set_mark(m);
3669 obj->incr_age();
3670 } else {
3671 m = m->incr_age();
3672 obj->set_mark(m);
3673 }
3674 _par_scan_state->age_table()->add(obj, word_sz);
3675 } else {
3676 obj->set_mark(m);
3677 }
3679 // preserve "next" mark bit
3680 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3681 if (!use_local_bitmaps ||
3682 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3683 // if we couldn't mark it on the local bitmap (this happens when
3684 // the object was not allocated in the GCLab), we have to bite
3685 // the bullet and do the standard parallel mark
3686 _cm->markAndGrayObjectIfNecessary(obj);
3687 }
3688 #if 1
3689 if (_g1->isMarkedNext(old)) {
3690 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3691 }
3692 #endif
3693 }
3695 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3696 surv_young_words[young_index] += word_sz;
3698 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3699 arrayOop(old)->set_length(0);
3700 oop* old_p = set_partial_array_mask(old);
3701 _par_scan_state->push_on_queue(old_p);
3702 } else {
3703 // No point in using the slower heap_region_containing() method,
3704 // given that we know obj is in the heap.
3705 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3706 obj->oop_iterate_backwards(_scanner);
3707 }
3708 } else {
3709 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3710 obj = forward_ptr;
3711 }
3712 return obj;
3713 }
3715 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee, bool skip_cset_test>
3716 template <class T>
3717 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee, skip_cset_test>
3718 ::do_oop_work(T* p) {
3719 oop obj = oopDesc::load_decode_heap_oop(p);
3720 assert(barrier != G1BarrierRS || obj != NULL,
3721 "Precondition: G1BarrierRS implies obj is nonNull");
3723 // The only time we skip the cset test is when we're scanning
3724 // references popped from the queue. And we only push on the queue
3725 // references that we know point into the cset, so no point in
3726 // checking again. But we'll leave an assert here for peace of mind.
3727 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
3729 // here the null check is implicit in the cset_fast_test() test
3730 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
3731 #if G1_REM_SET_LOGGING
3732 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
3733 "into CS.", p, (void*) obj);
3734 #endif
3735 if (obj->is_forwarded()) {
3736 oopDesc::encode_store_heap_oop(p, obj->forwardee());
3737 } else {
3738 oop copy_oop = copy_to_survivor_space(obj);
3739 oopDesc::encode_store_heap_oop(p, copy_oop);
3740 }
3741 // When scanning the RS, we only care about objs in CS.
3742 if (barrier == G1BarrierRS) {
3743 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3744 }
3745 }
3747 // When scanning moved objs, must look at all oops.
3748 if (barrier == G1BarrierEvac && obj != NULL) {
3749 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3750 }
3752 if (do_gen_barrier && obj != NULL) {
3753 par_do_barrier(p);
3754 }
3755 }
3757 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
3758 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(narrowOop* p);
3760 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
3761 assert(has_partial_array_mask(p), "invariant");
3762 oop old = clear_partial_array_mask(p);
3763 assert(old->is_objArray(), "must be obj array");
3764 assert(old->is_forwarded(), "must be forwarded");
3765 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
3767 objArrayOop obj = objArrayOop(old->forwardee());
3768 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
3769 // Process ParGCArrayScanChunk elements now
3770 // and push the remainder back onto queue
3771 int start = arrayOop(old)->length();
3772 int end = obj->length();
3773 int remainder = end - start;
3774 assert(start <= end, "just checking");
3775 if (remainder > 2 * ParGCArrayScanChunk) {
3776 // Test above combines last partial chunk with a full chunk
3777 end = start + ParGCArrayScanChunk;
3778 arrayOop(old)->set_length(end);
3779 // Push remainder.
3780 oop* old_p = set_partial_array_mask(old);
3781 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
3782 _par_scan_state->push_on_queue(old_p);
3783 } else {
3784 // Restore length so that the heap remains parsable in
3785 // case of evacuation failure.
3786 arrayOop(old)->set_length(end);
3787 }
3788 _scanner.set_region(_g1->heap_region_containing_raw(obj));
3789 // process our set of indices (include header in first chunk)
3790 obj->oop_iterate_range(&_scanner, start, end);
3791 }
3793 class G1ParEvacuateFollowersClosure : public VoidClosure {
3794 protected:
3795 G1CollectedHeap* _g1h;
3796 G1ParScanThreadState* _par_scan_state;
3797 RefToScanQueueSet* _queues;
3798 ParallelTaskTerminator* _terminator;
3800 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3801 RefToScanQueueSet* queues() { return _queues; }
3802 ParallelTaskTerminator* terminator() { return _terminator; }
3804 public:
3805 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
3806 G1ParScanThreadState* par_scan_state,
3807 RefToScanQueueSet* queues,
3808 ParallelTaskTerminator* terminator)
3809 : _g1h(g1h), _par_scan_state(par_scan_state),
3810 _queues(queues), _terminator(terminator) {}
3812 void do_void() {
3813 G1ParScanThreadState* pss = par_scan_state();
3814 while (true) {
3815 pss->trim_queue();
3816 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
3818 StarTask stolen_task;
3819 if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
3820 IF_G1_DETAILED_STATS(pss->note_steal());
3822 // slightly paranoid tests; I'm trying to catch potential
3823 // problems before we go into push_on_queue to know where the
3824 // problem is coming from
3825 assert((oop*)stolen_task != NULL, "Error");
3826 if (stolen_task.is_narrow()) {
3827 assert(UseCompressedOops, "Error");
3828 narrowOop* p = (narrowOop*) stolen_task;
3829 assert(has_partial_array_mask(p) ||
3830 _g1h->obj_in_cs(oopDesc::load_decode_heap_oop(p)), "Error");
3831 pss->push_on_queue(p);
3832 } else {
3833 oop* p = (oop*) stolen_task;
3834 assert(has_partial_array_mask(p) || _g1h->obj_in_cs(*p), "Error");
3835 pss->push_on_queue(p);
3836 }
3837 continue;
3838 }
3839 pss->start_term_time();
3840 if (terminator()->offer_termination()) break;
3841 pss->end_term_time();
3842 }
3843 pss->end_term_time();
3844 pss->retire_alloc_buffers();
3845 }
3846 };
3848 class G1ParTask : public AbstractGangTask {
3849 protected:
3850 G1CollectedHeap* _g1h;
3851 RefToScanQueueSet *_queues;
3852 ParallelTaskTerminator _terminator;
3853 int _n_workers;
3855 Mutex _stats_lock;
3856 Mutex* stats_lock() { return &_stats_lock; }
3858 size_t getNCards() {
3859 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
3860 / G1BlockOffsetSharedArray::N_bytes;
3861 }
3863 public:
3864 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
3865 : AbstractGangTask("G1 collection"),
3866 _g1h(g1h),
3867 _queues(task_queues),
3868 _terminator(workers, _queues),
3869 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
3870 _n_workers(workers)
3871 {}
3873 RefToScanQueueSet* queues() { return _queues; }
3875 RefToScanQueue *work_queue(int i) {
3876 return queues()->queue(i);
3877 }
3879 void work(int i) {
3880 if (i >= _n_workers) return; // no work needed this round
3881 ResourceMark rm;
3882 HandleMark hm;
3884 G1ParScanThreadState pss(_g1h, i);
3885 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
3886 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
3887 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
3889 pss.set_evac_closure(&scan_evac_cl);
3890 pss.set_evac_failure_closure(&evac_failure_cl);
3891 pss.set_partial_scan_closure(&partial_scan_cl);
3893 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
3894 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
3895 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
3897 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
3898 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
3899 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
3901 OopsInHeapRegionClosure *scan_root_cl;
3902 OopsInHeapRegionClosure *scan_perm_cl;
3903 OopsInHeapRegionClosure *scan_so_cl;
3905 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
3906 scan_root_cl = &scan_mark_root_cl;
3907 scan_perm_cl = &scan_mark_perm_cl;
3908 scan_so_cl = &scan_mark_heap_rs_cl;
3909 } else {
3910 scan_root_cl = &only_scan_root_cl;
3911 scan_perm_cl = &only_scan_perm_cl;
3912 scan_so_cl = &only_scan_heap_rs_cl;
3913 }
3915 pss.start_strong_roots();
3916 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
3917 SharedHeap::SO_AllClasses,
3918 scan_root_cl,
3919 &only_scan_heap_rs_cl,
3920 scan_so_cl,
3921 scan_perm_cl,
3922 i);
3923 pss.end_strong_roots();
3924 {
3925 double start = os::elapsedTime();
3926 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
3927 evac.do_void();
3928 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
3929 double term_ms = pss.term_time()*1000.0;
3930 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
3931 _g1h->g1_policy()->record_termination_time(i, term_ms);
3932 }
3933 if (G1UseSurvivorSpaces) {
3934 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
3935 }
3936 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
3938 // Clean up any par-expanded rem sets.
3939 HeapRegionRemSet::par_cleanup();
3941 MutexLocker x(stats_lock());
3942 if (ParallelGCVerbose) {
3943 gclog_or_tty->print("Thread %d complete:\n", i);
3944 #if G1_DETAILED_STATS
3945 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
3946 pss.pushes(),
3947 pss.pops(),
3948 pss.overflow_pushes(),
3949 pss.steals(),
3950 pss.steal_attempts());
3951 #endif
3952 double elapsed = pss.elapsed();
3953 double strong_roots = pss.strong_roots_time();
3954 double term = pss.term_time();
3955 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
3956 " Strong roots: %7.2f ms (%6.2f%%)\n"
3957 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
3958 elapsed * 1000.0,
3959 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
3960 term * 1000.0, (term*100.0/elapsed),
3961 pss.term_attempts());
3962 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
3963 gclog_or_tty->print(" Waste: %8dK\n"
3964 " Alloc Buffer: %8dK\n"
3965 " Undo: %8dK\n",
3966 (total_waste * HeapWordSize) / K,
3967 (pss.alloc_buffer_waste() * HeapWordSize) / K,
3968 (pss.undo_waste() * HeapWordSize) / K);
3969 }
3971 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
3972 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
3973 }
3974 };
3976 // *** Common G1 Evacuation Stuff
3978 void
3979 G1CollectedHeap::
3980 g1_process_strong_roots(bool collecting_perm_gen,
3981 SharedHeap::ScanningOption so,
3982 OopClosure* scan_non_heap_roots,
3983 OopsInHeapRegionClosure* scan_rs,
3984 OopsInHeapRegionClosure* scan_so,
3985 OopsInGenClosure* scan_perm,
3986 int worker_i) {
3987 // First scan the strong roots, including the perm gen.
3988 double ext_roots_start = os::elapsedTime();
3989 double closure_app_time_sec = 0.0;
3991 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
3992 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
3993 buf_scan_perm.set_generation(perm_gen());
3995 process_strong_roots(collecting_perm_gen, so,
3996 &buf_scan_non_heap_roots,
3997 &buf_scan_perm);
3998 // Finish up any enqueued closure apps.
3999 buf_scan_non_heap_roots.done();
4000 buf_scan_perm.done();
4001 double ext_roots_end = os::elapsedTime();
4002 g1_policy()->reset_obj_copy_time(worker_i);
4003 double obj_copy_time_sec =
4004 buf_scan_non_heap_roots.closure_app_seconds() +
4005 buf_scan_perm.closure_app_seconds();
4006 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4007 double ext_root_time_ms =
4008 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4009 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4011 // Scan strong roots in mark stack.
4012 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4013 concurrent_mark()->oops_do(scan_non_heap_roots);
4014 }
4015 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4016 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4018 // XXX What should this be doing in the parallel case?
4019 g1_policy()->record_collection_pause_end_CH_strong_roots();
4020 if (scan_so != NULL) {
4021 scan_scan_only_set(scan_so, worker_i);
4022 }
4023 // Now scan the complement of the collection set.
4024 if (scan_rs != NULL) {
4025 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4026 }
4027 // Finish with the ref_processor roots.
4028 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4029 ref_processor()->oops_do(scan_non_heap_roots);
4030 }
4031 g1_policy()->record_collection_pause_end_G1_strong_roots();
4032 _process_strong_tasks->all_tasks_completed();
4033 }
4035 void
4036 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4037 OopsInHeapRegionClosure* oc,
4038 int worker_i) {
4039 HeapWord* startAddr = r->bottom();
4040 HeapWord* endAddr = r->used_region().end();
4042 oc->set_region(r);
4044 HeapWord* p = r->bottom();
4045 HeapWord* t = r->top();
4046 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4047 while (p < t) {
4048 oop obj = oop(p);
4049 p += obj->oop_iterate(oc);
4050 }
4051 }
4053 void
4054 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4055 int worker_i) {
4056 double start = os::elapsedTime();
4058 BufferingOopsInHeapRegionClosure boc(oc);
4060 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4061 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4063 OopsInHeapRegionClosure *foc;
4064 if (g1_policy()->should_initiate_conc_mark())
4065 foc = &scan_and_mark;
4066 else
4067 foc = &scan_only;
4069 HeapRegion* hr;
4070 int n = 0;
4071 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4072 scan_scan_only_region(hr, foc, worker_i);
4073 ++n;
4074 }
4075 boc.done();
4077 double closure_app_s = boc.closure_app_seconds();
4078 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4079 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4080 g1_policy()->record_scan_only_time(worker_i, ms, n);
4081 }
4083 void
4084 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4085 OopClosure* non_root_closure) {
4086 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4087 }
4090 class SaveMarksClosure: public HeapRegionClosure {
4091 public:
4092 bool doHeapRegion(HeapRegion* r) {
4093 r->save_marks();
4094 return false;
4095 }
4096 };
4098 void G1CollectedHeap::save_marks() {
4099 if (ParallelGCThreads == 0) {
4100 SaveMarksClosure sm;
4101 heap_region_iterate(&sm);
4102 }
4103 // We do this even in the parallel case
4104 perm_gen()->save_marks();
4105 }
4107 void G1CollectedHeap::evacuate_collection_set() {
4108 set_evacuation_failed(false);
4110 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4111 concurrent_g1_refine()->set_use_cache(false);
4112 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4114 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4115 set_par_threads(n_workers);
4116 G1ParTask g1_par_task(this, n_workers, _task_queues);
4118 init_for_evac_failure(NULL);
4120 change_strong_roots_parity(); // In preparation for parallel strong roots.
4121 rem_set()->prepare_for_younger_refs_iterate(true);
4123 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4124 double start_par = os::elapsedTime();
4125 if (ParallelGCThreads > 0) {
4126 // The individual threads will set their evac-failure closures.
4127 workers()->run_task(&g1_par_task);
4128 } else {
4129 g1_par_task.work(0);
4130 }
4132 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4133 g1_policy()->record_par_time(par_time);
4134 set_par_threads(0);
4135 // Is this the right thing to do here? We don't save marks
4136 // on individual heap regions when we allocate from
4137 // them in parallel, so this seems like the correct place for this.
4138 retire_all_alloc_regions();
4139 {
4140 G1IsAliveClosure is_alive(this);
4141 G1KeepAliveClosure keep_alive(this);
4142 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4143 }
4144 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4146 concurrent_g1_refine()->clear_hot_cache();
4147 concurrent_g1_refine()->set_use_cache(true);
4149 finalize_for_evac_failure();
4151 // Must do this before removing self-forwarding pointers, which clears
4152 // the per-region evac-failure flags.
4153 concurrent_mark()->complete_marking_in_collection_set();
4155 if (evacuation_failed()) {
4156 remove_self_forwarding_pointers();
4157 if (PrintGCDetails) {
4158 gclog_or_tty->print(" (evacuation failed)");
4159 } else if (PrintGC) {
4160 gclog_or_tty->print("--");
4161 }
4162 }
4164 if (G1DeferredRSUpdate) {
4165 RedirtyLoggedCardTableEntryFastClosure redirty;
4166 dirty_card_queue_set().set_closure(&redirty);
4167 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4168 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4169 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4170 }
4172 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4173 }
4175 void G1CollectedHeap::free_region(HeapRegion* hr) {
4176 size_t pre_used = 0;
4177 size_t cleared_h_regions = 0;
4178 size_t freed_regions = 0;
4179 UncleanRegionList local_list;
4181 HeapWord* start = hr->bottom();
4182 HeapWord* end = hr->prev_top_at_mark_start();
4183 size_t used_bytes = hr->used();
4184 size_t live_bytes = hr->max_live_bytes();
4185 if (used_bytes > 0) {
4186 guarantee( live_bytes <= used_bytes, "invariant" );
4187 } else {
4188 guarantee( live_bytes == 0, "invariant" );
4189 }
4191 size_t garbage_bytes = used_bytes - live_bytes;
4192 if (garbage_bytes > 0)
4193 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4195 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4196 &local_list);
4197 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4198 &local_list);
4199 }
4201 void
4202 G1CollectedHeap::free_region_work(HeapRegion* hr,
4203 size_t& pre_used,
4204 size_t& cleared_h_regions,
4205 size_t& freed_regions,
4206 UncleanRegionList* list,
4207 bool par) {
4208 pre_used += hr->used();
4209 if (hr->isHumongous()) {
4210 assert(hr->startsHumongous(),
4211 "Only the start of a humongous region should be freed.");
4212 int ind = _hrs->find(hr);
4213 assert(ind != -1, "Should have an index.");
4214 // Clear the start region.
4215 hr->hr_clear(par, true /*clear_space*/);
4216 list->insert_before_head(hr);
4217 cleared_h_regions++;
4218 freed_regions++;
4219 // Clear any continued regions.
4220 ind++;
4221 while ((size_t)ind < n_regions()) {
4222 HeapRegion* hrc = _hrs->at(ind);
4223 if (!hrc->continuesHumongous()) break;
4224 // Otherwise, does continue the H region.
4225 assert(hrc->humongous_start_region() == hr, "Huh?");
4226 hrc->hr_clear(par, true /*clear_space*/);
4227 cleared_h_regions++;
4228 freed_regions++;
4229 list->insert_before_head(hrc);
4230 ind++;
4231 }
4232 } else {
4233 hr->hr_clear(par, true /*clear_space*/);
4234 list->insert_before_head(hr);
4235 freed_regions++;
4236 // If we're using clear2, this should not be enabled.
4237 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4238 }
4239 }
4241 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4242 size_t cleared_h_regions,
4243 size_t freed_regions,
4244 UncleanRegionList* list) {
4245 if (list != NULL && list->sz() > 0) {
4246 prepend_region_list_on_unclean_list(list);
4247 }
4248 // Acquire a lock, if we're parallel, to update possibly-shared
4249 // variables.
4250 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4251 {
4252 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4253 _summary_bytes_used -= pre_used;
4254 _num_humongous_regions -= (int) cleared_h_regions;
4255 _free_regions += freed_regions;
4256 }
4257 }
4260 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4261 while (list != NULL) {
4262 guarantee( list->is_young(), "invariant" );
4264 HeapWord* bottom = list->bottom();
4265 HeapWord* end = list->end();
4266 MemRegion mr(bottom, end);
4267 ct_bs->dirty(mr);
4269 list = list->get_next_young_region();
4270 }
4271 }
4274 class G1ParCleanupCTTask : public AbstractGangTask {
4275 CardTableModRefBS* _ct_bs;
4276 G1CollectedHeap* _g1h;
4277 public:
4278 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4279 G1CollectedHeap* g1h) :
4280 AbstractGangTask("G1 Par Cleanup CT Task"),
4281 _ct_bs(ct_bs),
4282 _g1h(g1h)
4283 { }
4285 void work(int i) {
4286 HeapRegion* r;
4287 while (r = _g1h->pop_dirty_cards_region()) {
4288 clear_cards(r);
4289 }
4290 }
4291 void clear_cards(HeapRegion* r) {
4292 // Cards for Survivor and Scan-Only regions will be dirtied later.
4293 if (!r->is_scan_only() && !r->is_survivor()) {
4294 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4295 }
4296 }
4297 };
4300 void G1CollectedHeap::cleanUpCardTable() {
4301 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4302 double start = os::elapsedTime();
4304 // Iterate over the dirty cards region list.
4305 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4306 if (ParallelGCThreads > 0) {
4307 set_par_threads(workers()->total_workers());
4308 workers()->run_task(&cleanup_task);
4309 set_par_threads(0);
4310 } else {
4311 while (_dirty_cards_region_list) {
4312 HeapRegion* r = _dirty_cards_region_list;
4313 cleanup_task.clear_cards(r);
4314 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4315 if (_dirty_cards_region_list == r) {
4316 // The last region.
4317 _dirty_cards_region_list = NULL;
4318 }
4319 r->set_next_dirty_cards_region(NULL);
4320 }
4321 }
4322 // now, redirty the cards of the scan-only and survivor regions
4323 // (it seemed faster to do it this way, instead of iterating over
4324 // all regions and then clearing / dirtying as appropriate)
4325 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4326 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4328 double elapsed = os::elapsedTime() - start;
4329 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4330 }
4333 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4334 if (g1_policy()->should_do_collection_pause(word_size)) {
4335 do_collection_pause();
4336 }
4337 }
4339 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4340 double young_time_ms = 0.0;
4341 double non_young_time_ms = 0.0;
4343 G1CollectorPolicy* policy = g1_policy();
4345 double start_sec = os::elapsedTime();
4346 bool non_young = true;
4348 HeapRegion* cur = cs_head;
4349 int age_bound = -1;
4350 size_t rs_lengths = 0;
4352 while (cur != NULL) {
4353 if (non_young) {
4354 if (cur->is_young()) {
4355 double end_sec = os::elapsedTime();
4356 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4357 non_young_time_ms += elapsed_ms;
4359 start_sec = os::elapsedTime();
4360 non_young = false;
4361 }
4362 } else {
4363 if (!cur->is_on_free_list()) {
4364 double end_sec = os::elapsedTime();
4365 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4366 young_time_ms += elapsed_ms;
4368 start_sec = os::elapsedTime();
4369 non_young = true;
4370 }
4371 }
4373 rs_lengths += cur->rem_set()->occupied();
4375 HeapRegion* next = cur->next_in_collection_set();
4376 assert(cur->in_collection_set(), "bad CS");
4377 cur->set_next_in_collection_set(NULL);
4378 cur->set_in_collection_set(false);
4380 if (cur->is_young()) {
4381 int index = cur->young_index_in_cset();
4382 guarantee( index != -1, "invariant" );
4383 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4384 size_t words_survived = _surviving_young_words[index];
4385 cur->record_surv_words_in_group(words_survived);
4386 } else {
4387 int index = cur->young_index_in_cset();
4388 guarantee( index == -1, "invariant" );
4389 }
4391 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4392 (!cur->is_young() && cur->young_index_in_cset() == -1),
4393 "invariant" );
4395 if (!cur->evacuation_failed()) {
4396 // And the region is empty.
4397 assert(!cur->is_empty(),
4398 "Should not have empty regions in a CS.");
4399 free_region(cur);
4400 } else {
4401 guarantee( !cur->is_scan_only(), "should not be scan only" );
4402 cur->uninstall_surv_rate_group();
4403 if (cur->is_young())
4404 cur->set_young_index_in_cset(-1);
4405 cur->set_not_young();
4406 cur->set_evacuation_failed(false);
4407 }
4408 cur = next;
4409 }
4411 policy->record_max_rs_lengths(rs_lengths);
4412 policy->cset_regions_freed();
4414 double end_sec = os::elapsedTime();
4415 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4416 if (non_young)
4417 non_young_time_ms += elapsed_ms;
4418 else
4419 young_time_ms += elapsed_ms;
4421 policy->record_young_free_cset_time_ms(young_time_ms);
4422 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4423 }
4425 HeapRegion*
4426 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4427 assert(ZF_mon->owned_by_self(), "Precondition");
4428 HeapRegion* res = pop_unclean_region_list_locked();
4429 if (res != NULL) {
4430 assert(!res->continuesHumongous() &&
4431 res->zero_fill_state() != HeapRegion::Allocated,
4432 "Only free regions on unclean list.");
4433 if (zero_filled) {
4434 res->ensure_zero_filled_locked();
4435 res->set_zero_fill_allocated();
4436 }
4437 }
4438 return res;
4439 }
4441 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4442 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4443 return alloc_region_from_unclean_list_locked(zero_filled);
4444 }
4446 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4447 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4448 put_region_on_unclean_list_locked(r);
4449 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4450 }
4452 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4453 MutexLockerEx x(Cleanup_mon);
4454 set_unclean_regions_coming_locked(b);
4455 }
4457 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4458 assert(Cleanup_mon->owned_by_self(), "Precondition");
4459 _unclean_regions_coming = b;
4460 // Wake up mutator threads that might be waiting for completeCleanup to
4461 // finish.
4462 if (!b) Cleanup_mon->notify_all();
4463 }
4465 void G1CollectedHeap::wait_for_cleanup_complete() {
4466 MutexLockerEx x(Cleanup_mon);
4467 wait_for_cleanup_complete_locked();
4468 }
4470 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4471 assert(Cleanup_mon->owned_by_self(), "precondition");
4472 while (_unclean_regions_coming) {
4473 Cleanup_mon->wait();
4474 }
4475 }
4477 void
4478 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4479 assert(ZF_mon->owned_by_self(), "precondition.");
4480 _unclean_region_list.insert_before_head(r);
4481 }
4483 void
4484 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4485 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4486 prepend_region_list_on_unclean_list_locked(list);
4487 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4488 }
4490 void
4491 G1CollectedHeap::
4492 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4493 assert(ZF_mon->owned_by_self(), "precondition.");
4494 _unclean_region_list.prepend_list(list);
4495 }
4497 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4498 assert(ZF_mon->owned_by_self(), "precondition.");
4499 HeapRegion* res = _unclean_region_list.pop();
4500 if (res != NULL) {
4501 // Inform ZF thread that there's a new unclean head.
4502 if (_unclean_region_list.hd() != NULL && should_zf())
4503 ZF_mon->notify_all();
4504 }
4505 return res;
4506 }
4508 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4509 assert(ZF_mon->owned_by_self(), "precondition.");
4510 return _unclean_region_list.hd();
4511 }
4514 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4515 assert(ZF_mon->owned_by_self(), "Precondition");
4516 HeapRegion* r = peek_unclean_region_list_locked();
4517 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4518 // Result of below must be equal to "r", since we hold the lock.
4519 (void)pop_unclean_region_list_locked();
4520 put_free_region_on_list_locked(r);
4521 return true;
4522 } else {
4523 return false;
4524 }
4525 }
4527 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4528 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4529 return move_cleaned_region_to_free_list_locked();
4530 }
4533 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4534 assert(ZF_mon->owned_by_self(), "precondition.");
4535 assert(_free_region_list_size == free_region_list_length(), "Inv");
4536 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4537 "Regions on free list must be zero filled");
4538 assert(!r->isHumongous(), "Must not be humongous.");
4539 assert(r->is_empty(), "Better be empty");
4540 assert(!r->is_on_free_list(),
4541 "Better not already be on free list");
4542 assert(!r->is_on_unclean_list(),
4543 "Better not already be on unclean list");
4544 r->set_on_free_list(true);
4545 r->set_next_on_free_list(_free_region_list);
4546 _free_region_list = r;
4547 _free_region_list_size++;
4548 assert(_free_region_list_size == free_region_list_length(), "Inv");
4549 }
4551 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4552 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4553 put_free_region_on_list_locked(r);
4554 }
4556 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4557 assert(ZF_mon->owned_by_self(), "precondition.");
4558 assert(_free_region_list_size == free_region_list_length(), "Inv");
4559 HeapRegion* res = _free_region_list;
4560 if (res != NULL) {
4561 _free_region_list = res->next_from_free_list();
4562 _free_region_list_size--;
4563 res->set_on_free_list(false);
4564 res->set_next_on_free_list(NULL);
4565 assert(_free_region_list_size == free_region_list_length(), "Inv");
4566 }
4567 return res;
4568 }
4571 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4572 // By self, or on behalf of self.
4573 assert(Heap_lock->is_locked(), "Precondition");
4574 HeapRegion* res = NULL;
4575 bool first = true;
4576 while (res == NULL) {
4577 if (zero_filled || !first) {
4578 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4579 res = pop_free_region_list_locked();
4580 if (res != NULL) {
4581 assert(!res->zero_fill_is_allocated(),
4582 "No allocated regions on free list.");
4583 res->set_zero_fill_allocated();
4584 } else if (!first) {
4585 break; // We tried both, time to return NULL.
4586 }
4587 }
4589 if (res == NULL) {
4590 res = alloc_region_from_unclean_list(zero_filled);
4591 }
4592 assert(res == NULL ||
4593 !zero_filled ||
4594 res->zero_fill_is_allocated(),
4595 "We must have allocated the region we're returning");
4596 first = false;
4597 }
4598 return res;
4599 }
4601 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4602 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4603 {
4604 HeapRegion* prev = NULL;
4605 HeapRegion* cur = _unclean_region_list.hd();
4606 while (cur != NULL) {
4607 HeapRegion* next = cur->next_from_unclean_list();
4608 if (cur->zero_fill_is_allocated()) {
4609 // Remove from the list.
4610 if (prev == NULL) {
4611 (void)_unclean_region_list.pop();
4612 } else {
4613 _unclean_region_list.delete_after(prev);
4614 }
4615 cur->set_on_unclean_list(false);
4616 cur->set_next_on_unclean_list(NULL);
4617 } else {
4618 prev = cur;
4619 }
4620 cur = next;
4621 }
4622 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4623 "Inv");
4624 }
4626 {
4627 HeapRegion* prev = NULL;
4628 HeapRegion* cur = _free_region_list;
4629 while (cur != NULL) {
4630 HeapRegion* next = cur->next_from_free_list();
4631 if (cur->zero_fill_is_allocated()) {
4632 // Remove from the list.
4633 if (prev == NULL) {
4634 _free_region_list = cur->next_from_free_list();
4635 } else {
4636 prev->set_next_on_free_list(cur->next_from_free_list());
4637 }
4638 cur->set_on_free_list(false);
4639 cur->set_next_on_free_list(NULL);
4640 _free_region_list_size--;
4641 } else {
4642 prev = cur;
4643 }
4644 cur = next;
4645 }
4646 assert(_free_region_list_size == free_region_list_length(), "Inv");
4647 }
4648 }
4650 bool G1CollectedHeap::verify_region_lists() {
4651 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4652 return verify_region_lists_locked();
4653 }
4655 bool G1CollectedHeap::verify_region_lists_locked() {
4656 HeapRegion* unclean = _unclean_region_list.hd();
4657 while (unclean != NULL) {
4658 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4659 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4660 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4661 "Everything else is possible.");
4662 unclean = unclean->next_from_unclean_list();
4663 }
4664 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4666 HeapRegion* free_r = _free_region_list;
4667 while (free_r != NULL) {
4668 assert(free_r->is_on_free_list(), "Well, it is!");
4669 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4670 switch (free_r->zero_fill_state()) {
4671 case HeapRegion::NotZeroFilled:
4672 case HeapRegion::ZeroFilling:
4673 guarantee(false, "Should not be on free list.");
4674 break;
4675 default:
4676 // Everything else is possible.
4677 break;
4678 }
4679 free_r = free_r->next_from_free_list();
4680 }
4681 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4682 // If we didn't do an assertion...
4683 return true;
4684 }
4686 size_t G1CollectedHeap::free_region_list_length() {
4687 assert(ZF_mon->owned_by_self(), "precondition.");
4688 size_t len = 0;
4689 HeapRegion* cur = _free_region_list;
4690 while (cur != NULL) {
4691 len++;
4692 cur = cur->next_from_free_list();
4693 }
4694 return len;
4695 }
4697 size_t G1CollectedHeap::unclean_region_list_length() {
4698 assert(ZF_mon->owned_by_self(), "precondition.");
4699 return _unclean_region_list.length();
4700 }
4702 size_t G1CollectedHeap::n_regions() {
4703 return _hrs->length();
4704 }
4706 size_t G1CollectedHeap::max_regions() {
4707 return
4708 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4709 HeapRegion::GrainBytes;
4710 }
4712 size_t G1CollectedHeap::free_regions() {
4713 /* Possibly-expensive assert.
4714 assert(_free_regions == count_free_regions(),
4715 "_free_regions is off.");
4716 */
4717 return _free_regions;
4718 }
4720 bool G1CollectedHeap::should_zf() {
4721 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4722 }
4724 class RegionCounter: public HeapRegionClosure {
4725 size_t _n;
4726 public:
4727 RegionCounter() : _n(0) {}
4728 bool doHeapRegion(HeapRegion* r) {
4729 if (r->is_empty()) {
4730 assert(!r->isHumongous(), "H regions should not be empty.");
4731 _n++;
4732 }
4733 return false;
4734 }
4735 int res() { return (int) _n; }
4736 };
4738 size_t G1CollectedHeap::count_free_regions() {
4739 RegionCounter rc;
4740 heap_region_iterate(&rc);
4741 size_t n = rc.res();
4742 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4743 n--;
4744 return n;
4745 }
4747 size_t G1CollectedHeap::count_free_regions_list() {
4748 size_t n = 0;
4749 size_t o = 0;
4750 ZF_mon->lock_without_safepoint_check();
4751 HeapRegion* cur = _free_region_list;
4752 while (cur != NULL) {
4753 cur = cur->next_from_free_list();
4754 n++;
4755 }
4756 size_t m = unclean_region_list_length();
4757 ZF_mon->unlock();
4758 return n + m;
4759 }
4761 bool G1CollectedHeap::should_set_young_locked() {
4762 assert(heap_lock_held_for_gc(),
4763 "the heap lock should already be held by or for this thread");
4764 return (g1_policy()->in_young_gc_mode() &&
4765 g1_policy()->should_add_next_region_to_young_list());
4766 }
4768 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4769 assert(heap_lock_held_for_gc(),
4770 "the heap lock should already be held by or for this thread");
4771 _young_list->push_region(hr);
4772 g1_policy()->set_region_short_lived(hr);
4773 }
4775 class NoYoungRegionsClosure: public HeapRegionClosure {
4776 private:
4777 bool _success;
4778 public:
4779 NoYoungRegionsClosure() : _success(true) { }
4780 bool doHeapRegion(HeapRegion* r) {
4781 if (r->is_young()) {
4782 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
4783 r->bottom(), r->end());
4784 _success = false;
4785 }
4786 return false;
4787 }
4788 bool success() { return _success; }
4789 };
4791 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
4792 bool check_sample) {
4793 bool ret = true;
4795 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
4796 if (!ignore_scan_only_list) {
4797 NoYoungRegionsClosure closure;
4798 heap_region_iterate(&closure);
4799 ret = ret && closure.success();
4800 }
4802 return ret;
4803 }
4805 void G1CollectedHeap::empty_young_list() {
4806 assert(heap_lock_held_for_gc(),
4807 "the heap lock should already be held by or for this thread");
4808 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
4810 _young_list->empty_list();
4811 }
4813 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
4814 bool no_allocs = true;
4815 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
4816 HeapRegion* r = _gc_alloc_regions[ap];
4817 no_allocs = r == NULL || r->saved_mark_at_top();
4818 }
4819 return no_allocs;
4820 }
4822 void G1CollectedHeap::retire_all_alloc_regions() {
4823 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4824 HeapRegion* r = _gc_alloc_regions[ap];
4825 if (r != NULL) {
4826 // Check for aliases.
4827 bool has_processed_alias = false;
4828 for (int i = 0; i < ap; ++i) {
4829 if (_gc_alloc_regions[i] == r) {
4830 has_processed_alias = true;
4831 break;
4832 }
4833 }
4834 if (!has_processed_alias) {
4835 retire_alloc_region(r, false /* par */);
4836 }
4837 }
4838 }
4839 }
4842 // Done at the start of full GC.
4843 void G1CollectedHeap::tear_down_region_lists() {
4844 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4845 while (pop_unclean_region_list_locked() != NULL) ;
4846 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
4847 "Postconditions of loop.")
4848 while (pop_free_region_list_locked() != NULL) ;
4849 assert(_free_region_list == NULL, "Postcondition of loop.");
4850 if (_free_region_list_size != 0) {
4851 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
4852 print_on(gclog_or_tty, true /* extended */);
4853 }
4854 assert(_free_region_list_size == 0, "Postconditions of loop.");
4855 }
4858 class RegionResetter: public HeapRegionClosure {
4859 G1CollectedHeap* _g1;
4860 int _n;
4861 public:
4862 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4863 bool doHeapRegion(HeapRegion* r) {
4864 if (r->continuesHumongous()) return false;
4865 if (r->top() > r->bottom()) {
4866 if (r->top() < r->end()) {
4867 Copy::fill_to_words(r->top(),
4868 pointer_delta(r->end(), r->top()));
4869 }
4870 r->set_zero_fill_allocated();
4871 } else {
4872 assert(r->is_empty(), "tautology");
4873 _n++;
4874 switch (r->zero_fill_state()) {
4875 case HeapRegion::NotZeroFilled:
4876 case HeapRegion::ZeroFilling:
4877 _g1->put_region_on_unclean_list_locked(r);
4878 break;
4879 case HeapRegion::Allocated:
4880 r->set_zero_fill_complete();
4881 // no break; go on to put on free list.
4882 case HeapRegion::ZeroFilled:
4883 _g1->put_free_region_on_list_locked(r);
4884 break;
4885 }
4886 }
4887 return false;
4888 }
4890 int getFreeRegionCount() {return _n;}
4891 };
4893 // Done at the end of full GC.
4894 void G1CollectedHeap::rebuild_region_lists() {
4895 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4896 // This needs to go at the end of the full GC.
4897 RegionResetter rs;
4898 heap_region_iterate(&rs);
4899 _free_regions = rs.getFreeRegionCount();
4900 // Tell the ZF thread it may have work to do.
4901 if (should_zf()) ZF_mon->notify_all();
4902 }
4904 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
4905 G1CollectedHeap* _g1;
4906 int _n;
4907 public:
4908 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4909 bool doHeapRegion(HeapRegion* r) {
4910 if (r->continuesHumongous()) return false;
4911 if (r->top() > r->bottom()) {
4912 // There are assertions in "set_zero_fill_needed()" below that
4913 // require top() == bottom(), so this is technically illegal.
4914 // We'll skirt the law here, by making that true temporarily.
4915 DEBUG_ONLY(HeapWord* save_top = r->top();
4916 r->set_top(r->bottom()));
4917 r->set_zero_fill_needed();
4918 DEBUG_ONLY(r->set_top(save_top));
4919 }
4920 return false;
4921 }
4922 };
4924 // Done at the start of full GC.
4925 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
4926 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4927 // This needs to go at the end of the full GC.
4928 UsedRegionsNeedZeroFillSetter rs;
4929 heap_region_iterate(&rs);
4930 }
4932 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
4933 _refine_cte_cl->set_concurrent(concurrent);
4934 }
4936 #ifndef PRODUCT
4938 class PrintHeapRegionClosure: public HeapRegionClosure {
4939 public:
4940 bool doHeapRegion(HeapRegion *r) {
4941 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
4942 if (r != NULL) {
4943 if (r->is_on_free_list())
4944 gclog_or_tty->print("Free ");
4945 if (r->is_young())
4946 gclog_or_tty->print("Young ");
4947 if (r->isHumongous())
4948 gclog_or_tty->print("Is Humongous ");
4949 r->print();
4950 }
4951 return false;
4952 }
4953 };
4955 class SortHeapRegionClosure : public HeapRegionClosure {
4956 size_t young_regions,free_regions, unclean_regions;
4957 size_t hum_regions, count;
4958 size_t unaccounted, cur_unclean, cur_alloc;
4959 size_t total_free;
4960 HeapRegion* cur;
4961 public:
4962 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
4963 free_regions(0), unclean_regions(0),
4964 hum_regions(0),
4965 count(0), unaccounted(0),
4966 cur_alloc(0), total_free(0)
4967 {}
4968 bool doHeapRegion(HeapRegion *r) {
4969 count++;
4970 if (r->is_on_free_list()) free_regions++;
4971 else if (r->is_on_unclean_list()) unclean_regions++;
4972 else if (r->isHumongous()) hum_regions++;
4973 else if (r->is_young()) young_regions++;
4974 else if (r == cur) cur_alloc++;
4975 else unaccounted++;
4976 return false;
4977 }
4978 void print() {
4979 total_free = free_regions + unclean_regions;
4980 gclog_or_tty->print("%d regions\n", count);
4981 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
4982 total_free, free_regions, unclean_regions);
4983 gclog_or_tty->print("%d humongous %d young\n",
4984 hum_regions, young_regions);
4985 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
4986 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
4987 }
4988 };
4990 void G1CollectedHeap::print_region_counts() {
4991 SortHeapRegionClosure sc(_cur_alloc_region);
4992 PrintHeapRegionClosure cl;
4993 heap_region_iterate(&cl);
4994 heap_region_iterate(&sc);
4995 sc.print();
4996 print_region_accounting_info();
4997 };
4999 bool G1CollectedHeap::regions_accounted_for() {
5000 // TODO: regions accounting for young/survivor/tenured
5001 return true;
5002 }
5004 bool G1CollectedHeap::print_region_accounting_info() {
5005 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5006 free_regions(),
5007 count_free_regions(), count_free_regions_list(),
5008 _free_region_list_size, _unclean_region_list.sz());
5009 gclog_or_tty->print_cr("cur_alloc: %d.",
5010 (_cur_alloc_region == NULL ? 0 : 1));
5011 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5013 // TODO: check regions accounting for young/survivor/tenured
5014 return true;
5015 }
5017 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5018 HeapRegion* hr = heap_region_containing(p);
5019 if (hr == NULL) {
5020 return is_in_permanent(p);
5021 } else {
5022 return hr->is_in(p);
5023 }
5024 }
5025 #endif // PRODUCT
5027 void G1CollectedHeap::g1_unimplemented() {
5028 // Unimplemented();
5029 }