Fri, 27 Feb 2009 13:27:09 -0800
6810672: Comment typos
Summary: I have collected some typos I have found while looking at the code.
Reviewed-by: kvn, never
1 /*
2 * Copyright 2001-2008 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 // Finds the first HeapRegion.
46 // No longer used, but might be handy someday.
48 class FindFirstRegionClosure: public HeapRegionClosure {
49 HeapRegion* _a_region;
50 public:
51 FindFirstRegionClosure() : _a_region(NULL) {}
52 bool doHeapRegion(HeapRegion* r) {
53 _a_region = r;
54 return true;
55 }
56 HeapRegion* result() { return _a_region; }
57 };
60 class RefineCardTableEntryClosure: public CardTableEntryClosure {
61 SuspendibleThreadSet* _sts;
62 G1RemSet* _g1rs;
63 ConcurrentG1Refine* _cg1r;
64 bool _concurrent;
65 public:
66 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
67 G1RemSet* g1rs,
68 ConcurrentG1Refine* cg1r) :
69 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
70 {}
71 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
72 _g1rs->concurrentRefineOneCard(card_ptr, worker_i);
73 if (_concurrent && _sts->should_yield()) {
74 // Caller will actually yield.
75 return false;
76 }
77 // Otherwise, we finished successfully; return true.
78 return true;
79 }
80 void set_concurrent(bool b) { _concurrent = b; }
81 };
84 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
85 int _calls;
86 G1CollectedHeap* _g1h;
87 CardTableModRefBS* _ctbs;
88 int _histo[256];
89 public:
90 ClearLoggedCardTableEntryClosure() :
91 _calls(0)
92 {
93 _g1h = G1CollectedHeap::heap();
94 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
95 for (int i = 0; i < 256; i++) _histo[i] = 0;
96 }
97 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
98 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
99 _calls++;
100 unsigned char* ujb = (unsigned char*)card_ptr;
101 int ind = (int)(*ujb);
102 _histo[ind]++;
103 *card_ptr = -1;
104 }
105 return true;
106 }
107 int calls() { return _calls; }
108 void print_histo() {
109 gclog_or_tty->print_cr("Card table value histogram:");
110 for (int i = 0; i < 256; i++) {
111 if (_histo[i] != 0) {
112 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
113 }
114 }
115 }
116 };
118 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
119 int _calls;
120 G1CollectedHeap* _g1h;
121 CardTableModRefBS* _ctbs;
122 public:
123 RedirtyLoggedCardTableEntryClosure() :
124 _calls(0)
125 {
126 _g1h = G1CollectedHeap::heap();
127 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
128 }
129 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
130 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
131 _calls++;
132 *card_ptr = 0;
133 }
134 return true;
135 }
136 int calls() { return _calls; }
137 };
139 YoungList::YoungList(G1CollectedHeap* g1h)
140 : _g1h(g1h), _head(NULL),
141 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
142 _length(0), _scan_only_length(0),
143 _last_sampled_rs_lengths(0),
144 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
145 {
146 guarantee( check_list_empty(false), "just making sure..." );
147 }
149 void YoungList::push_region(HeapRegion *hr) {
150 assert(!hr->is_young(), "should not already be young");
151 assert(hr->get_next_young_region() == NULL, "cause it should!");
153 hr->set_next_young_region(_head);
154 _head = hr;
156 hr->set_young();
157 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
158 ++_length;
159 }
161 void YoungList::add_survivor_region(HeapRegion* hr) {
162 assert(hr->is_survivor(), "should be flagged as survivor region");
163 assert(hr->get_next_young_region() == NULL, "cause it should!");
165 hr->set_next_young_region(_survivor_head);
166 if (_survivor_head == NULL) {
167 _survivor_tail = hr;
168 }
169 _survivor_head = hr;
171 ++_survivor_length;
172 }
174 HeapRegion* YoungList::pop_region() {
175 while (_head != NULL) {
176 assert( length() > 0, "list should not be empty" );
177 HeapRegion* ret = _head;
178 _head = ret->get_next_young_region();
179 ret->set_next_young_region(NULL);
180 --_length;
181 assert(ret->is_young(), "region should be very young");
183 // Replace 'Survivor' region type with 'Young'. So the region will
184 // be treated as a young region and will not be 'confused' with
185 // newly created survivor regions.
186 if (ret->is_survivor()) {
187 ret->set_young();
188 }
190 if (!ret->is_scan_only()) {
191 return ret;
192 }
194 // scan-only, we'll add it to the scan-only list
195 if (_scan_only_tail == NULL) {
196 guarantee( _scan_only_head == NULL, "invariant" );
198 _scan_only_head = ret;
199 _curr_scan_only = ret;
200 } else {
201 guarantee( _scan_only_head != NULL, "invariant" );
202 _scan_only_tail->set_next_young_region(ret);
203 }
204 guarantee( ret->get_next_young_region() == NULL, "invariant" );
205 _scan_only_tail = ret;
207 // no need to be tagged as scan-only any more
208 ret->set_young();
210 ++_scan_only_length;
211 }
212 assert( length() == 0, "list should be empty" );
213 return NULL;
214 }
216 void YoungList::empty_list(HeapRegion* list) {
217 while (list != NULL) {
218 HeapRegion* next = list->get_next_young_region();
219 list->set_next_young_region(NULL);
220 list->uninstall_surv_rate_group();
221 list->set_not_young();
222 list = next;
223 }
224 }
226 void YoungList::empty_list() {
227 assert(check_list_well_formed(), "young list should be well formed");
229 empty_list(_head);
230 _head = NULL;
231 _length = 0;
233 empty_list(_scan_only_head);
234 _scan_only_head = NULL;
235 _scan_only_tail = NULL;
236 _scan_only_length = 0;
237 _curr_scan_only = NULL;
239 empty_list(_survivor_head);
240 _survivor_head = NULL;
241 _survivor_tail = NULL;
242 _survivor_length = 0;
244 _last_sampled_rs_lengths = 0;
246 assert(check_list_empty(false), "just making sure...");
247 }
249 bool YoungList::check_list_well_formed() {
250 bool ret = true;
252 size_t length = 0;
253 HeapRegion* curr = _head;
254 HeapRegion* last = NULL;
255 while (curr != NULL) {
256 if (!curr->is_young() || curr->is_scan_only()) {
257 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
258 "incorrectly tagged (%d, %d)",
259 curr->bottom(), curr->end(),
260 curr->is_young(), curr->is_scan_only());
261 ret = false;
262 }
263 ++length;
264 last = curr;
265 curr = curr->get_next_young_region();
266 }
267 ret = ret && (length == _length);
269 if (!ret) {
270 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
271 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
272 length, _length);
273 }
275 bool scan_only_ret = true;
276 length = 0;
277 curr = _scan_only_head;
278 last = NULL;
279 while (curr != NULL) {
280 if (!curr->is_young() || curr->is_scan_only()) {
281 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
282 "incorrectly tagged (%d, %d)",
283 curr->bottom(), curr->end(),
284 curr->is_young(), curr->is_scan_only());
285 scan_only_ret = false;
286 }
287 ++length;
288 last = curr;
289 curr = curr->get_next_young_region();
290 }
291 scan_only_ret = scan_only_ret && (length == _scan_only_length);
293 if ( (last != _scan_only_tail) ||
294 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
295 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
296 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
297 scan_only_ret = false;
298 }
300 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
301 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
302 scan_only_ret = false;
303 }
305 if (!scan_only_ret) {
306 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
307 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
308 length, _scan_only_length);
309 }
311 return ret && scan_only_ret;
312 }
314 bool YoungList::check_list_empty(bool ignore_scan_only_list,
315 bool check_sample) {
316 bool ret = true;
318 if (_length != 0) {
319 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
320 _length);
321 ret = false;
322 }
323 if (check_sample && _last_sampled_rs_lengths != 0) {
324 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
325 ret = false;
326 }
327 if (_head != NULL) {
328 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
329 ret = false;
330 }
331 if (!ret) {
332 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
333 }
335 if (ignore_scan_only_list)
336 return ret;
338 bool scan_only_ret = true;
339 if (_scan_only_length != 0) {
340 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
341 _scan_only_length);
342 scan_only_ret = false;
343 }
344 if (_scan_only_head != NULL) {
345 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
346 scan_only_ret = false;
347 }
348 if (_scan_only_tail != NULL) {
349 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
350 scan_only_ret = false;
351 }
352 if (!scan_only_ret) {
353 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
354 }
356 return ret && scan_only_ret;
357 }
359 void
360 YoungList::rs_length_sampling_init() {
361 _sampled_rs_lengths = 0;
362 _curr = _head;
363 }
365 bool
366 YoungList::rs_length_sampling_more() {
367 return _curr != NULL;
368 }
370 void
371 YoungList::rs_length_sampling_next() {
372 assert( _curr != NULL, "invariant" );
373 _sampled_rs_lengths += _curr->rem_set()->occupied();
374 _curr = _curr->get_next_young_region();
375 if (_curr == NULL) {
376 _last_sampled_rs_lengths = _sampled_rs_lengths;
377 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
378 }
379 }
381 void
382 YoungList::reset_auxilary_lists() {
383 // We could have just "moved" the scan-only list to the young list.
384 // However, the scan-only list is ordered according to the region
385 // age in descending order, so, by moving one entry at a time, we
386 // ensure that it is recreated in ascending order.
388 guarantee( is_empty(), "young list should be empty" );
389 assert(check_list_well_formed(), "young list should be well formed");
391 // Add survivor regions to SurvRateGroup.
392 _g1h->g1_policy()->note_start_adding_survivor_regions();
393 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
394 for (HeapRegion* curr = _survivor_head;
395 curr != NULL;
396 curr = curr->get_next_young_region()) {
397 _g1h->g1_policy()->set_region_survivors(curr);
398 }
399 _g1h->g1_policy()->note_stop_adding_survivor_regions();
401 if (_survivor_head != NULL) {
402 _head = _survivor_head;
403 _length = _survivor_length + _scan_only_length;
404 _survivor_tail->set_next_young_region(_scan_only_head);
405 } else {
406 _head = _scan_only_head;
407 _length = _scan_only_length;
408 }
410 for (HeapRegion* curr = _scan_only_head;
411 curr != NULL;
412 curr = curr->get_next_young_region()) {
413 curr->recalculate_age_in_surv_rate_group();
414 }
415 _scan_only_head = NULL;
416 _scan_only_tail = NULL;
417 _scan_only_length = 0;
418 _curr_scan_only = NULL;
420 _survivor_head = NULL;
421 _survivor_tail = NULL;
422 _survivor_length = 0;
423 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
425 assert(check_list_well_formed(), "young list should be well formed");
426 }
428 void YoungList::print() {
429 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
430 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
432 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
433 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
434 HeapRegion *curr = lists[list];
435 if (curr == NULL)
436 gclog_or_tty->print_cr(" empty");
437 while (curr != NULL) {
438 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
439 "age: %4d, y: %d, s-o: %d, surv: %d",
440 curr->bottom(), curr->end(),
441 curr->top(),
442 curr->prev_top_at_mark_start(),
443 curr->next_top_at_mark_start(),
444 curr->top_at_conc_mark_count(),
445 curr->age_in_surv_rate_group_cond(),
446 curr->is_young(),
447 curr->is_scan_only(),
448 curr->is_survivor());
449 curr = curr->get_next_young_region();
450 }
451 }
453 gclog_or_tty->print_cr("");
454 }
456 void G1CollectedHeap::stop_conc_gc_threads() {
457 _cg1r->cg1rThread()->stop();
458 _czft->stop();
459 _cmThread->stop();
460 }
463 void G1CollectedHeap::check_ct_logs_at_safepoint() {
464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
465 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
467 // Count the dirty cards at the start.
468 CountNonCleanMemRegionClosure count1(this);
469 ct_bs->mod_card_iterate(&count1);
470 int orig_count = count1.n();
472 // First clear the logged cards.
473 ClearLoggedCardTableEntryClosure clear;
474 dcqs.set_closure(&clear);
475 dcqs.apply_closure_to_all_completed_buffers();
476 dcqs.iterate_closure_all_threads(false);
477 clear.print_histo();
479 // Now ensure that there's no dirty cards.
480 CountNonCleanMemRegionClosure count2(this);
481 ct_bs->mod_card_iterate(&count2);
482 if (count2.n() != 0) {
483 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
484 count2.n(), orig_count);
485 }
486 guarantee(count2.n() == 0, "Card table should be clean.");
488 RedirtyLoggedCardTableEntryClosure redirty;
489 JavaThread::dirty_card_queue_set().set_closure(&redirty);
490 dcqs.apply_closure_to_all_completed_buffers();
491 dcqs.iterate_closure_all_threads(false);
492 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
493 clear.calls(), orig_count);
494 guarantee(redirty.calls() == clear.calls(),
495 "Or else mechanism is broken.");
497 CountNonCleanMemRegionClosure count3(this);
498 ct_bs->mod_card_iterate(&count3);
499 if (count3.n() != orig_count) {
500 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
501 orig_count, count3.n());
502 guarantee(count3.n() >= orig_count, "Should have restored them all.");
503 }
505 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
506 }
508 // Private class members.
510 G1CollectedHeap* G1CollectedHeap::_g1h;
512 // Private methods.
514 // Finds a HeapRegion that can be used to allocate a given size of block.
517 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
518 bool do_expand,
519 bool zero_filled) {
520 ConcurrentZFThread::note_region_alloc();
521 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
522 if (res == NULL && do_expand) {
523 expand(word_size * HeapWordSize);
524 res = alloc_free_region_from_lists(zero_filled);
525 assert(res == NULL ||
526 (!res->isHumongous() &&
527 (!zero_filled ||
528 res->zero_fill_state() == HeapRegion::Allocated)),
529 "Alloc Regions must be zero filled (and non-H)");
530 }
531 if (res != NULL && res->is_empty()) _free_regions--;
532 assert(res == NULL ||
533 (!res->isHumongous() &&
534 (!zero_filled ||
535 res->zero_fill_state() == HeapRegion::Allocated)),
536 "Non-young alloc Regions must be zero filled (and non-H)");
538 if (G1TraceRegions) {
539 if (res != NULL) {
540 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
541 "top "PTR_FORMAT,
542 res->hrs_index(), res->bottom(), res->end(), res->top());
543 }
544 }
546 return res;
547 }
549 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
550 size_t word_size,
551 bool zero_filled) {
552 HeapRegion* alloc_region = NULL;
553 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
554 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
555 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
556 alloc_region->set_survivor();
557 }
558 ++_gc_alloc_region_counts[purpose];
559 } else {
560 g1_policy()->note_alloc_region_limit_reached(purpose);
561 }
562 return alloc_region;
563 }
565 // If could fit into free regions w/o expansion, try.
566 // Otherwise, if can expand, do so.
567 // Otherwise, if using ex regions might help, try with ex given back.
568 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
569 assert(regions_accounted_for(), "Region leakage!");
571 // We can't allocate H regions while cleanupComplete is running, since
572 // some of the regions we find to be empty might not yet be added to the
573 // unclean list. (If we're already at a safepoint, this call is
574 // unnecessary, not to mention wrong.)
575 if (!SafepointSynchronize::is_at_safepoint())
576 wait_for_cleanup_complete();
578 size_t num_regions =
579 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
581 // Special case if < one region???
583 // Remember the ft size.
584 size_t x_size = expansion_regions();
586 HeapWord* res = NULL;
587 bool eliminated_allocated_from_lists = false;
589 // Can the allocation potentially fit in the free regions?
590 if (free_regions() >= num_regions) {
591 res = _hrs->obj_allocate(word_size);
592 }
593 if (res == NULL) {
594 // Try expansion.
595 size_t fs = _hrs->free_suffix();
596 if (fs + x_size >= num_regions) {
597 expand((num_regions - fs) * HeapRegion::GrainBytes);
598 res = _hrs->obj_allocate(word_size);
599 assert(res != NULL, "This should have worked.");
600 } else {
601 // Expansion won't help. Are there enough free regions if we get rid
602 // of reservations?
603 size_t avail = free_regions();
604 if (avail >= num_regions) {
605 res = _hrs->obj_allocate(word_size);
606 if (res != NULL) {
607 remove_allocated_regions_from_lists();
608 eliminated_allocated_from_lists = true;
609 }
610 }
611 }
612 }
613 if (res != NULL) {
614 // Increment by the number of regions allocated.
615 // FIXME: Assumes regions all of size GrainBytes.
616 #ifndef PRODUCT
617 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
618 HeapRegion::GrainWords));
619 #endif
620 if (!eliminated_allocated_from_lists)
621 remove_allocated_regions_from_lists();
622 _summary_bytes_used += word_size * HeapWordSize;
623 _free_regions -= num_regions;
624 _num_humongous_regions += (int) num_regions;
625 }
626 assert(regions_accounted_for(), "Region Leakage");
627 return res;
628 }
630 HeapWord*
631 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
632 bool permit_collection_pause) {
633 HeapWord* res = NULL;
634 HeapRegion* allocated_young_region = NULL;
636 assert( SafepointSynchronize::is_at_safepoint() ||
637 Heap_lock->owned_by_self(), "pre condition of the call" );
639 if (isHumongous(word_size)) {
640 // Allocation of a humongous object can, in a sense, complete a
641 // partial region, if the previous alloc was also humongous, and
642 // caused the test below to succeed.
643 if (permit_collection_pause)
644 do_collection_pause_if_appropriate(word_size);
645 res = humongousObjAllocate(word_size);
646 assert(_cur_alloc_region == NULL
647 || !_cur_alloc_region->isHumongous(),
648 "Prevent a regression of this bug.");
650 } else {
651 // We may have concurrent cleanup working at the time. Wait for it
652 // to complete. In the future we would probably want to make the
653 // concurrent cleanup truly concurrent by decoupling it from the
654 // allocation.
655 if (!SafepointSynchronize::is_at_safepoint())
656 wait_for_cleanup_complete();
657 // If we do a collection pause, this will be reset to a non-NULL
658 // value. If we don't, nulling here ensures that we allocate a new
659 // region below.
660 if (_cur_alloc_region != NULL) {
661 // We're finished with the _cur_alloc_region.
662 _summary_bytes_used += _cur_alloc_region->used();
663 _cur_alloc_region = NULL;
664 }
665 assert(_cur_alloc_region == NULL, "Invariant.");
666 // Completion of a heap region is perhaps a good point at which to do
667 // a collection pause.
668 if (permit_collection_pause)
669 do_collection_pause_if_appropriate(word_size);
670 // Make sure we have an allocation region available.
671 if (_cur_alloc_region == NULL) {
672 if (!SafepointSynchronize::is_at_safepoint())
673 wait_for_cleanup_complete();
674 bool next_is_young = should_set_young_locked();
675 // If the next region is not young, make sure it's zero-filled.
676 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
677 if (_cur_alloc_region != NULL) {
678 _summary_bytes_used -= _cur_alloc_region->used();
679 if (next_is_young) {
680 set_region_short_lived_locked(_cur_alloc_region);
681 allocated_young_region = _cur_alloc_region;
682 }
683 }
684 }
685 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
686 "Prevent a regression of this bug.");
688 // Now retry the allocation.
689 if (_cur_alloc_region != NULL) {
690 res = _cur_alloc_region->allocate(word_size);
691 }
692 }
694 // NOTE: fails frequently in PRT
695 assert(regions_accounted_for(), "Region leakage!");
697 if (res != NULL) {
698 if (!SafepointSynchronize::is_at_safepoint()) {
699 assert( permit_collection_pause, "invariant" );
700 assert( Heap_lock->owned_by_self(), "invariant" );
701 Heap_lock->unlock();
702 }
704 if (allocated_young_region != NULL) {
705 HeapRegion* hr = allocated_young_region;
706 HeapWord* bottom = hr->bottom();
707 HeapWord* end = hr->end();
708 MemRegion mr(bottom, end);
709 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
710 }
711 }
713 assert( SafepointSynchronize::is_at_safepoint() ||
714 (res == NULL && Heap_lock->owned_by_self()) ||
715 (res != NULL && !Heap_lock->owned_by_self()),
716 "post condition of the call" );
718 return res;
719 }
721 HeapWord*
722 G1CollectedHeap::mem_allocate(size_t word_size,
723 bool is_noref,
724 bool is_tlab,
725 bool* gc_overhead_limit_was_exceeded) {
726 debug_only(check_for_valid_allocation_state());
727 assert(no_gc_in_progress(), "Allocation during gc not allowed");
728 HeapWord* result = NULL;
730 // Loop until the allocation is satisified,
731 // or unsatisfied after GC.
732 for (int try_count = 1; /* return or throw */; try_count += 1) {
733 int gc_count_before;
734 {
735 Heap_lock->lock();
736 result = attempt_allocation(word_size);
737 if (result != NULL) {
738 // attempt_allocation should have unlocked the heap lock
739 assert(is_in(result), "result not in heap");
740 return result;
741 }
742 // Read the gc count while the heap lock is held.
743 gc_count_before = SharedHeap::heap()->total_collections();
744 Heap_lock->unlock();
745 }
747 // Create the garbage collection operation...
748 VM_G1CollectForAllocation op(word_size,
749 gc_count_before);
751 // ...and get the VM thread to execute it.
752 VMThread::execute(&op);
753 if (op.prologue_succeeded()) {
754 result = op.result();
755 assert(result == NULL || is_in(result), "result not in heap");
756 return result;
757 }
759 // Give a warning if we seem to be looping forever.
760 if ((QueuedAllocationWarningCount > 0) &&
761 (try_count % QueuedAllocationWarningCount == 0)) {
762 warning("G1CollectedHeap::mem_allocate_work retries %d times",
763 try_count);
764 }
765 }
766 }
768 void G1CollectedHeap::abandon_cur_alloc_region() {
769 if (_cur_alloc_region != NULL) {
770 // We're finished with the _cur_alloc_region.
771 if (_cur_alloc_region->is_empty()) {
772 _free_regions++;
773 free_region(_cur_alloc_region);
774 } else {
775 _summary_bytes_used += _cur_alloc_region->used();
776 }
777 _cur_alloc_region = NULL;
778 }
779 }
781 class PostMCRemSetClearClosure: public HeapRegionClosure {
782 ModRefBarrierSet* _mr_bs;
783 public:
784 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
785 bool doHeapRegion(HeapRegion* r) {
786 r->reset_gc_time_stamp();
787 if (r->continuesHumongous())
788 return false;
789 HeapRegionRemSet* hrrs = r->rem_set();
790 if (hrrs != NULL) hrrs->clear();
791 // You might think here that we could clear just the cards
792 // corresponding to the used region. But no: if we leave a dirty card
793 // in a region we might allocate into, then it would prevent that card
794 // from being enqueued, and cause it to be missed.
795 // Re: the performance cost: we shouldn't be doing full GC anyway!
796 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
797 return false;
798 }
799 };
802 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
803 ModRefBarrierSet* _mr_bs;
804 public:
805 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
806 bool doHeapRegion(HeapRegion* r) {
807 if (r->continuesHumongous()) return false;
808 if (r->used_region().word_size() != 0) {
809 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
810 }
811 return false;
812 }
813 };
815 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
816 size_t word_size) {
817 ResourceMark rm;
819 if (full && DisableExplicitGC) {
820 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
821 return;
822 }
824 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
825 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
827 if (GC_locker::is_active()) {
828 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
829 }
831 {
832 IsGCActiveMark x;
834 // Timing
835 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
836 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
837 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
839 double start = os::elapsedTime();
840 GCOverheadReporter::recordSTWStart(start);
841 g1_policy()->record_full_collection_start();
843 gc_prologue(true);
844 increment_total_collections();
846 size_t g1h_prev_used = used();
847 assert(used() == recalculate_used(), "Should be equal");
849 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
850 HandleMark hm; // Discard invalid handles created during verification
851 prepare_for_verify();
852 gclog_or_tty->print(" VerifyBeforeGC:");
853 Universe::verify(true);
854 }
855 assert(regions_accounted_for(), "Region leakage!");
857 COMPILER2_PRESENT(DerivedPointerTable::clear());
859 // We want to discover references, but not process them yet.
860 // This mode is disabled in
861 // instanceRefKlass::process_discovered_references if the
862 // generation does some collection work, or
863 // instanceRefKlass::enqueue_discovered_references if the
864 // generation returns without doing any work.
865 ref_processor()->disable_discovery();
866 ref_processor()->abandon_partial_discovery();
867 ref_processor()->verify_no_references_recorded();
869 // Abandon current iterations of concurrent marking and concurrent
870 // refinement, if any are in progress.
871 concurrent_mark()->abort();
873 // Make sure we'll choose a new allocation region afterwards.
874 abandon_cur_alloc_region();
875 assert(_cur_alloc_region == NULL, "Invariant.");
876 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
877 tear_down_region_lists();
878 set_used_regions_to_need_zero_fill();
879 if (g1_policy()->in_young_gc_mode()) {
880 empty_young_list();
881 g1_policy()->set_full_young_gcs(true);
882 }
884 // Temporarily make reference _discovery_ single threaded (non-MT).
885 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
887 // Temporarily make refs discovery atomic
888 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
890 // Temporarily clear _is_alive_non_header
891 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
893 ref_processor()->enable_discovery();
894 ref_processor()->setup_policy(clear_all_soft_refs);
896 // Do collection work
897 {
898 HandleMark hm; // Discard invalid handles created during gc
899 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
900 }
901 // Because freeing humongous regions may have added some unclean
902 // regions, it is necessary to tear down again before rebuilding.
903 tear_down_region_lists();
904 rebuild_region_lists();
906 _summary_bytes_used = recalculate_used();
908 ref_processor()->enqueue_discovered_references();
910 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
912 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
913 HandleMark hm; // Discard invalid handles created during verification
914 gclog_or_tty->print(" VerifyAfterGC:");
915 Universe::verify(false);
916 }
917 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
919 reset_gc_time_stamp();
920 // Since everything potentially moved, we will clear all remembered
921 // sets, and clear all cards. Later we will also cards in the used
922 // portion of the heap after the resizing (which could be a shrinking.)
923 // We will also reset the GC time stamps of the regions.
924 PostMCRemSetClearClosure rs_clear(mr_bs());
925 heap_region_iterate(&rs_clear);
927 // Resize the heap if necessary.
928 resize_if_necessary_after_full_collection(full ? 0 : word_size);
930 // Since everything potentially moved, we will clear all remembered
931 // sets, but also dirty all cards corresponding to used regions.
932 PostMCRemSetInvalidateClosure rs_invalidate(mr_bs());
933 heap_region_iterate(&rs_invalidate);
934 if (_cg1r->use_cache()) {
935 _cg1r->clear_and_record_card_counts();
936 _cg1r->clear_hot_cache();
937 }
939 if (PrintGC) {
940 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
941 }
943 if (true) { // FIXME
944 // Ask the permanent generation to adjust size for full collections
945 perm()->compute_new_size();
946 }
948 double end = os::elapsedTime();
949 GCOverheadReporter::recordSTWEnd(end);
950 g1_policy()->record_full_collection_end();
952 #ifdef TRACESPINNING
953 ParallelTaskTerminator::print_termination_counts();
954 #endif
956 gc_epilogue(true);
958 // Abandon concurrent refinement. This must happen last: in the
959 // dirty-card logging system, some cards may be dirty by weak-ref
960 // processing, and may be enqueued. But the whole card table is
961 // dirtied, so this should abandon those logs, and set "do_traversal"
962 // to true.
963 concurrent_g1_refine()->set_pya_restart();
965 assert(regions_accounted_for(), "Region leakage!");
966 }
968 if (g1_policy()->in_young_gc_mode()) {
969 _young_list->reset_sampled_info();
970 assert( check_young_list_empty(false, false),
971 "young list should be empty at this point");
972 }
973 }
975 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
976 do_collection(true, clear_all_soft_refs, 0);
977 }
979 // This code is mostly copied from TenuredGeneration.
980 void
981 G1CollectedHeap::
982 resize_if_necessary_after_full_collection(size_t word_size) {
983 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
985 // Include the current allocation, if any, and bytes that will be
986 // pre-allocated to support collections, as "used".
987 const size_t used_after_gc = used();
988 const size_t capacity_after_gc = capacity();
989 const size_t free_after_gc = capacity_after_gc - used_after_gc;
991 // We don't have floating point command-line arguments
992 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
993 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
994 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
995 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
997 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
998 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1000 // Don't shrink less than the initial size.
1001 minimum_desired_capacity =
1002 MAX2(minimum_desired_capacity,
1003 collector_policy()->initial_heap_byte_size());
1004 maximum_desired_capacity =
1005 MAX2(maximum_desired_capacity,
1006 collector_policy()->initial_heap_byte_size());
1008 // We are failing here because minimum_desired_capacity is
1009 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1010 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1012 if (PrintGC && Verbose) {
1013 const double free_percentage = ((double)free_after_gc) / capacity();
1014 gclog_or_tty->print_cr("Computing new size after full GC ");
1015 gclog_or_tty->print_cr(" "
1016 " minimum_free_percentage: %6.2f",
1017 minimum_free_percentage);
1018 gclog_or_tty->print_cr(" "
1019 " maximum_free_percentage: %6.2f",
1020 maximum_free_percentage);
1021 gclog_or_tty->print_cr(" "
1022 " capacity: %6.1fK"
1023 " minimum_desired_capacity: %6.1fK"
1024 " maximum_desired_capacity: %6.1fK",
1025 capacity() / (double) K,
1026 minimum_desired_capacity / (double) K,
1027 maximum_desired_capacity / (double) K);
1028 gclog_or_tty->print_cr(" "
1029 " free_after_gc : %6.1fK"
1030 " used_after_gc : %6.1fK",
1031 free_after_gc / (double) K,
1032 used_after_gc / (double) K);
1033 gclog_or_tty->print_cr(" "
1034 " free_percentage: %6.2f",
1035 free_percentage);
1036 }
1037 if (capacity() < minimum_desired_capacity) {
1038 // Don't expand unless it's significant
1039 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1040 expand(expand_bytes);
1041 if (PrintGC && Verbose) {
1042 gclog_or_tty->print_cr(" expanding:"
1043 " minimum_desired_capacity: %6.1fK"
1044 " expand_bytes: %6.1fK",
1045 minimum_desired_capacity / (double) K,
1046 expand_bytes / (double) K);
1047 }
1049 // No expansion, now see if we want to shrink
1050 } else if (capacity() > maximum_desired_capacity) {
1051 // Capacity too large, compute shrinking size
1052 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1053 shrink(shrink_bytes);
1054 if (PrintGC && Verbose) {
1055 gclog_or_tty->print_cr(" "
1056 " shrinking:"
1057 " initSize: %.1fK"
1058 " maximum_desired_capacity: %.1fK",
1059 collector_policy()->initial_heap_byte_size() / (double) K,
1060 maximum_desired_capacity / (double) K);
1061 gclog_or_tty->print_cr(" "
1062 " shrink_bytes: %.1fK",
1063 shrink_bytes / (double) K);
1064 }
1065 }
1066 }
1069 HeapWord*
1070 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1071 HeapWord* result = NULL;
1073 // In a G1 heap, we're supposed to keep allocation from failing by
1074 // incremental pauses. Therefore, at least for now, we'll favor
1075 // expansion over collection. (This might change in the future if we can
1076 // do something smarter than full collection to satisfy a failed alloc.)
1078 result = expand_and_allocate(word_size);
1079 if (result != NULL) {
1080 assert(is_in(result), "result not in heap");
1081 return result;
1082 }
1084 // OK, I guess we have to try collection.
1086 do_collection(false, false, word_size);
1088 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1090 if (result != NULL) {
1091 assert(is_in(result), "result not in heap");
1092 return result;
1093 }
1095 // Try collecting soft references.
1096 do_collection(false, true, word_size);
1097 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1098 if (result != NULL) {
1099 assert(is_in(result), "result not in heap");
1100 return result;
1101 }
1103 // What else? We might try synchronous finalization later. If the total
1104 // space available is large enough for the allocation, then a more
1105 // complete compaction phase than we've tried so far might be
1106 // appropriate.
1107 return NULL;
1108 }
1110 // Attempting to expand the heap sufficiently
1111 // to support an allocation of the given "word_size". If
1112 // successful, perform the allocation and return the address of the
1113 // allocated block, or else "NULL".
1115 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1116 size_t expand_bytes = word_size * HeapWordSize;
1117 if (expand_bytes < MinHeapDeltaBytes) {
1118 expand_bytes = MinHeapDeltaBytes;
1119 }
1120 expand(expand_bytes);
1121 assert(regions_accounted_for(), "Region leakage!");
1122 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1123 return result;
1124 }
1126 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1127 size_t pre_used = 0;
1128 size_t cleared_h_regions = 0;
1129 size_t freed_regions = 0;
1130 UncleanRegionList local_list;
1131 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1132 freed_regions, &local_list);
1134 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1135 &local_list);
1136 return pre_used;
1137 }
1139 void
1140 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1141 size_t& pre_used,
1142 size_t& cleared_h,
1143 size_t& freed_regions,
1144 UncleanRegionList* list,
1145 bool par) {
1146 assert(!hr->continuesHumongous(), "should have filtered these out");
1147 size_t res = 0;
1148 if (!hr->popular() && hr->used() > 0 && hr->garbage_bytes() == hr->used()) {
1149 if (!hr->is_young()) {
1150 if (G1PolicyVerbose > 0)
1151 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1152 " during cleanup", hr, hr->used());
1153 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1154 }
1155 }
1156 }
1158 // FIXME: both this and shrink could probably be more efficient by
1159 // doing one "VirtualSpace::expand_by" call rather than several.
1160 void G1CollectedHeap::expand(size_t expand_bytes) {
1161 size_t old_mem_size = _g1_storage.committed_size();
1162 // We expand by a minimum of 1K.
1163 expand_bytes = MAX2(expand_bytes, (size_t)K);
1164 size_t aligned_expand_bytes =
1165 ReservedSpace::page_align_size_up(expand_bytes);
1166 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1167 HeapRegion::GrainBytes);
1168 expand_bytes = aligned_expand_bytes;
1169 while (expand_bytes > 0) {
1170 HeapWord* base = (HeapWord*)_g1_storage.high();
1171 // Commit more storage.
1172 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1173 if (!successful) {
1174 expand_bytes = 0;
1175 } else {
1176 expand_bytes -= HeapRegion::GrainBytes;
1177 // Expand the committed region.
1178 HeapWord* high = (HeapWord*) _g1_storage.high();
1179 _g1_committed.set_end(high);
1180 // Create a new HeapRegion.
1181 MemRegion mr(base, high);
1182 bool is_zeroed = !_g1_max_committed.contains(base);
1183 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1185 // Now update max_committed if necessary.
1186 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1188 // Add it to the HeapRegionSeq.
1189 _hrs->insert(hr);
1190 // Set the zero-fill state, according to whether it's already
1191 // zeroed.
1192 {
1193 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1194 if (is_zeroed) {
1195 hr->set_zero_fill_complete();
1196 put_free_region_on_list_locked(hr);
1197 } else {
1198 hr->set_zero_fill_needed();
1199 put_region_on_unclean_list_locked(hr);
1200 }
1201 }
1202 _free_regions++;
1203 // And we used up an expansion region to create it.
1204 _expansion_regions--;
1205 // Tell the cardtable about it.
1206 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1207 // And the offset table as well.
1208 _bot_shared->resize(_g1_committed.word_size());
1209 }
1210 }
1211 if (Verbose && PrintGC) {
1212 size_t new_mem_size = _g1_storage.committed_size();
1213 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1214 old_mem_size/K, aligned_expand_bytes/K,
1215 new_mem_size/K);
1216 }
1217 }
1219 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1220 {
1221 size_t old_mem_size = _g1_storage.committed_size();
1222 size_t aligned_shrink_bytes =
1223 ReservedSpace::page_align_size_down(shrink_bytes);
1224 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1225 HeapRegion::GrainBytes);
1226 size_t num_regions_deleted = 0;
1227 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1229 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1230 if (mr.byte_size() > 0)
1231 _g1_storage.shrink_by(mr.byte_size());
1232 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1234 _g1_committed.set_end(mr.start());
1235 _free_regions -= num_regions_deleted;
1236 _expansion_regions += num_regions_deleted;
1238 // Tell the cardtable about it.
1239 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1241 // And the offset table as well.
1242 _bot_shared->resize(_g1_committed.word_size());
1244 HeapRegionRemSet::shrink_heap(n_regions());
1246 if (Verbose && PrintGC) {
1247 size_t new_mem_size = _g1_storage.committed_size();
1248 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1249 old_mem_size/K, aligned_shrink_bytes/K,
1250 new_mem_size/K);
1251 }
1252 }
1254 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1255 release_gc_alloc_regions();
1256 tear_down_region_lists(); // We will rebuild them in a moment.
1257 shrink_helper(shrink_bytes);
1258 rebuild_region_lists();
1259 }
1261 // Public methods.
1263 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1264 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1265 #endif // _MSC_VER
1268 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1269 SharedHeap(policy_),
1270 _g1_policy(policy_),
1271 _ref_processor(NULL),
1272 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1273 _bot_shared(NULL),
1274 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1275 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1276 _evac_failure_scan_stack(NULL) ,
1277 _mark_in_progress(false),
1278 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1279 _cur_alloc_region(NULL),
1280 _refine_cte_cl(NULL),
1281 _free_region_list(NULL), _free_region_list_size(0),
1282 _free_regions(0),
1283 _popular_object_boundary(NULL),
1284 _cur_pop_hr_index(0),
1285 _popular_regions_to_be_evacuated(NULL),
1286 _pop_obj_rc_at_copy(),
1287 _full_collection(false),
1288 _unclean_region_list(),
1289 _unclean_regions_coming(false),
1290 _young_list(new YoungList(this)),
1291 _gc_time_stamp(0),
1292 _surviving_young_words(NULL),
1293 _in_cset_fast_test(NULL),
1294 _in_cset_fast_test_base(NULL)
1295 {
1296 _g1h = this; // To catch bugs.
1297 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1298 vm_exit_during_initialization("Failed necessary allocation.");
1299 }
1300 int n_queues = MAX2((int)ParallelGCThreads, 1);
1301 _task_queues = new RefToScanQueueSet(n_queues);
1303 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1304 assert(n_rem_sets > 0, "Invariant.");
1306 HeapRegionRemSetIterator** iter_arr =
1307 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1308 for (int i = 0; i < n_queues; i++) {
1309 iter_arr[i] = new HeapRegionRemSetIterator();
1310 }
1311 _rem_set_iterator = iter_arr;
1313 for (int i = 0; i < n_queues; i++) {
1314 RefToScanQueue* q = new RefToScanQueue();
1315 q->initialize();
1316 _task_queues->register_queue(i, q);
1317 }
1319 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1320 _gc_alloc_regions[ap] = NULL;
1321 _gc_alloc_region_counts[ap] = 0;
1322 }
1323 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1324 }
1326 jint G1CollectedHeap::initialize() {
1327 os::enable_vtime();
1329 // Necessary to satisfy locking discipline assertions.
1331 MutexLocker x(Heap_lock);
1333 // While there are no constraints in the GC code that HeapWordSize
1334 // be any particular value, there are multiple other areas in the
1335 // system which believe this to be true (e.g. oop->object_size in some
1336 // cases incorrectly returns the size in wordSize units rather than
1337 // HeapWordSize).
1338 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1340 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1341 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1343 // Ensure that the sizes are properly aligned.
1344 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1345 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1347 // We allocate this in any case, but only do no work if the command line
1348 // param is off.
1349 _cg1r = new ConcurrentG1Refine();
1351 // Reserve the maximum.
1352 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1353 // Includes the perm-gen.
1354 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1355 HeapRegion::GrainBytes,
1356 false /*ism*/);
1358 if (!heap_rs.is_reserved()) {
1359 vm_exit_during_initialization("Could not reserve enough space for object heap");
1360 return JNI_ENOMEM;
1361 }
1363 // It is important to do this in a way such that concurrent readers can't
1364 // temporarily think somethings in the heap. (I've actually seen this
1365 // happen in asserts: DLD.)
1366 _reserved.set_word_size(0);
1367 _reserved.set_start((HeapWord*)heap_rs.base());
1368 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1370 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1372 _num_humongous_regions = 0;
1374 // Create the gen rem set (and barrier set) for the entire reserved region.
1375 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1376 set_barrier_set(rem_set()->bs());
1377 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1378 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1379 } else {
1380 vm_exit_during_initialization("G1 requires a mod ref bs.");
1381 return JNI_ENOMEM;
1382 }
1384 // Also create a G1 rem set.
1385 if (G1UseHRIntoRS) {
1386 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1387 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1388 } else {
1389 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1390 return JNI_ENOMEM;
1391 }
1392 } else {
1393 _g1_rem_set = new StupidG1RemSet(this);
1394 }
1396 // Carve out the G1 part of the heap.
1398 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1399 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1400 g1_rs.size()/HeapWordSize);
1401 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1403 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1405 _g1_storage.initialize(g1_rs, 0);
1406 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1407 _g1_max_committed = _g1_committed;
1408 _hrs = new HeapRegionSeq(_expansion_regions);
1409 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1410 guarantee(_cur_alloc_region == NULL, "from constructor");
1412 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1413 heap_word_size(init_byte_size));
1415 _g1h = this;
1417 // Create the ConcurrentMark data structure and thread.
1418 // (Must do this late, so that "max_regions" is defined.)
1419 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1420 _cmThread = _cm->cmThread();
1422 // ...and the concurrent zero-fill thread, if necessary.
1423 if (G1ConcZeroFill) {
1424 _czft = new ConcurrentZFThread();
1425 }
1429 // Allocate the popular regions; take them off free lists.
1430 size_t pop_byte_size = G1NumPopularRegions * HeapRegion::GrainBytes;
1431 expand(pop_byte_size);
1432 _popular_object_boundary =
1433 _g1_reserved.start() + (G1NumPopularRegions * HeapRegion::GrainWords);
1434 for (int i = 0; i < G1NumPopularRegions; i++) {
1435 HeapRegion* hr = newAllocRegion(HeapRegion::GrainWords);
1436 // assert(hr != NULL && hr->bottom() < _popular_object_boundary,
1437 // "Should be enough, and all should be below boundary.");
1438 hr->set_popular(true);
1439 }
1440 assert(_cur_pop_hr_index == 0, "Start allocating at the first region.");
1442 // Initialize the from_card cache structure of HeapRegionRemSet.
1443 HeapRegionRemSet::init_heap(max_regions());
1445 // Now expand into the rest of the initial heap size.
1446 expand(init_byte_size - pop_byte_size);
1448 // Perform any initialization actions delegated to the policy.
1449 g1_policy()->init();
1451 g1_policy()->note_start_of_mark_thread();
1453 _refine_cte_cl =
1454 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1455 g1_rem_set(),
1456 concurrent_g1_refine());
1457 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1459 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1460 SATB_Q_FL_lock,
1461 0,
1462 Shared_SATB_Q_lock);
1463 if (G1RSBarrierUseQueue) {
1464 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1465 DirtyCardQ_FL_lock,
1466 G1DirtyCardQueueMax,
1467 Shared_DirtyCardQ_lock);
1468 }
1469 // In case we're keeping closure specialization stats, initialize those
1470 // counts and that mechanism.
1471 SpecializationStats::clear();
1473 _gc_alloc_region_list = NULL;
1475 // Do later initialization work for concurrent refinement.
1476 _cg1r->init();
1478 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1479 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1481 return JNI_OK;
1482 }
1484 void G1CollectedHeap::ref_processing_init() {
1485 SharedHeap::ref_processing_init();
1486 MemRegion mr = reserved_region();
1487 _ref_processor = ReferenceProcessor::create_ref_processor(
1488 mr, // span
1489 false, // Reference discovery is not atomic
1490 // (though it shouldn't matter here.)
1491 true, // mt_discovery
1492 NULL, // is alive closure: need to fill this in for efficiency
1493 ParallelGCThreads,
1494 ParallelRefProcEnabled,
1495 true); // Setting next fields of discovered
1496 // lists requires a barrier.
1497 }
1499 size_t G1CollectedHeap::capacity() const {
1500 return _g1_committed.byte_size();
1501 }
1503 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1504 int worker_i) {
1505 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1506 int n_completed_buffers = 0;
1507 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1508 n_completed_buffers++;
1509 }
1510 g1_policy()->record_update_rs_processed_buffers(worker_i,
1511 (double) n_completed_buffers);
1512 dcqs.clear_n_completed_buffers();
1513 // Finish up the queue...
1514 if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
1515 g1_rem_set());
1516 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1517 }
1520 // Computes the sum of the storage used by the various regions.
1522 size_t G1CollectedHeap::used() const {
1523 assert(Heap_lock->owner() != NULL,
1524 "Should be owned on this thread's behalf.");
1525 size_t result = _summary_bytes_used;
1526 if (_cur_alloc_region != NULL)
1527 result += _cur_alloc_region->used();
1528 return result;
1529 }
1531 class SumUsedClosure: public HeapRegionClosure {
1532 size_t _used;
1533 public:
1534 SumUsedClosure() : _used(0) {}
1535 bool doHeapRegion(HeapRegion* r) {
1536 if (!r->continuesHumongous()) {
1537 _used += r->used();
1538 }
1539 return false;
1540 }
1541 size_t result() { return _used; }
1542 };
1544 size_t G1CollectedHeap::recalculate_used() const {
1545 SumUsedClosure blk;
1546 _hrs->iterate(&blk);
1547 return blk.result();
1548 }
1550 #ifndef PRODUCT
1551 class SumUsedRegionsClosure: public HeapRegionClosure {
1552 size_t _num;
1553 public:
1554 // _num is set to 1 to account for the popular region
1555 SumUsedRegionsClosure() : _num(G1NumPopularRegions) {}
1556 bool doHeapRegion(HeapRegion* r) {
1557 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1558 _num += 1;
1559 }
1560 return false;
1561 }
1562 size_t result() { return _num; }
1563 };
1565 size_t G1CollectedHeap::recalculate_used_regions() const {
1566 SumUsedRegionsClosure blk;
1567 _hrs->iterate(&blk);
1568 return blk.result();
1569 }
1570 #endif // PRODUCT
1572 size_t G1CollectedHeap::unsafe_max_alloc() {
1573 if (_free_regions > 0) return HeapRegion::GrainBytes;
1574 // otherwise, is there space in the current allocation region?
1576 // We need to store the current allocation region in a local variable
1577 // here. The problem is that this method doesn't take any locks and
1578 // there may be other threads which overwrite the current allocation
1579 // region field. attempt_allocation(), for example, sets it to NULL
1580 // and this can happen *after* the NULL check here but before the call
1581 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1582 // to be a problem in the optimized build, since the two loads of the
1583 // current allocation region field are optimized away.
1584 HeapRegion* car = _cur_alloc_region;
1586 // FIXME: should iterate over all regions?
1587 if (car == NULL) {
1588 return 0;
1589 }
1590 return car->free();
1591 }
1593 void G1CollectedHeap::collect(GCCause::Cause cause) {
1594 // The caller doesn't have the Heap_lock
1595 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1596 MutexLocker ml(Heap_lock);
1597 collect_locked(cause);
1598 }
1600 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1601 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1602 assert(Heap_lock->is_locked(), "Precondition#2");
1603 GCCauseSetter gcs(this, cause);
1604 switch (cause) {
1605 case GCCause::_heap_inspection:
1606 case GCCause::_heap_dump: {
1607 HandleMark hm;
1608 do_full_collection(false); // don't clear all soft refs
1609 break;
1610 }
1611 default: // XXX FIX ME
1612 ShouldNotReachHere(); // Unexpected use of this function
1613 }
1614 }
1617 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1618 // Don't want to do a GC until cleanup is completed.
1619 wait_for_cleanup_complete();
1621 // Read the GC count while holding the Heap_lock
1622 int gc_count_before = SharedHeap::heap()->total_collections();
1623 {
1624 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1625 VM_G1CollectFull op(gc_count_before, cause);
1626 VMThread::execute(&op);
1627 }
1628 }
1630 bool G1CollectedHeap::is_in(const void* p) const {
1631 if (_g1_committed.contains(p)) {
1632 HeapRegion* hr = _hrs->addr_to_region(p);
1633 return hr->is_in(p);
1634 } else {
1635 return _perm_gen->as_gen()->is_in(p);
1636 }
1637 }
1639 // Iteration functions.
1641 // Iterates an OopClosure over all ref-containing fields of objects
1642 // within a HeapRegion.
1644 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1645 MemRegion _mr;
1646 OopClosure* _cl;
1647 public:
1648 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1649 : _mr(mr), _cl(cl) {}
1650 bool doHeapRegion(HeapRegion* r) {
1651 if (! r->continuesHumongous()) {
1652 r->oop_iterate(_cl);
1653 }
1654 return false;
1655 }
1656 };
1658 void G1CollectedHeap::oop_iterate(OopClosure* cl) {
1659 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1660 _hrs->iterate(&blk);
1661 }
1663 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
1664 IterateOopClosureRegionClosure blk(mr, cl);
1665 _hrs->iterate(&blk);
1666 }
1668 // Iterates an ObjectClosure over all objects within a HeapRegion.
1670 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1671 ObjectClosure* _cl;
1672 public:
1673 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1674 bool doHeapRegion(HeapRegion* r) {
1675 if (! r->continuesHumongous()) {
1676 r->object_iterate(_cl);
1677 }
1678 return false;
1679 }
1680 };
1682 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1683 IterateObjectClosureRegionClosure blk(cl);
1684 _hrs->iterate(&blk);
1685 }
1687 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1688 // FIXME: is this right?
1689 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1690 }
1692 // Calls a SpaceClosure on a HeapRegion.
1694 class SpaceClosureRegionClosure: public HeapRegionClosure {
1695 SpaceClosure* _cl;
1696 public:
1697 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1698 bool doHeapRegion(HeapRegion* r) {
1699 _cl->do_space(r);
1700 return false;
1701 }
1702 };
1704 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1705 SpaceClosureRegionClosure blk(cl);
1706 _hrs->iterate(&blk);
1707 }
1709 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1710 _hrs->iterate(cl);
1711 }
1713 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1714 HeapRegionClosure* cl) {
1715 _hrs->iterate_from(r, cl);
1716 }
1718 void
1719 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1720 _hrs->iterate_from(idx, cl);
1721 }
1723 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1725 void
1726 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1727 int worker,
1728 jint claim_value) {
1729 const size_t regions = n_regions();
1730 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1731 // try to spread out the starting points of the workers
1732 const size_t start_index = regions / worker_num * (size_t) worker;
1734 // each worker will actually look at all regions
1735 for (size_t count = 0; count < regions; ++count) {
1736 const size_t index = (start_index + count) % regions;
1737 assert(0 <= index && index < regions, "sanity");
1738 HeapRegion* r = region_at(index);
1739 // we'll ignore "continues humongous" regions (we'll process them
1740 // when we come across their corresponding "start humongous"
1741 // region) and regions already claimed
1742 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1743 continue;
1744 }
1745 // OK, try to claim it
1746 if (r->claimHeapRegion(claim_value)) {
1747 // success!
1748 assert(!r->continuesHumongous(), "sanity");
1749 if (r->startsHumongous()) {
1750 // If the region is "starts humongous" we'll iterate over its
1751 // "continues humongous" first; in fact we'll do them
1752 // first. The order is important. In on case, calling the
1753 // closure on the "starts humongous" region might de-allocate
1754 // and clear all its "continues humongous" regions and, as a
1755 // result, we might end up processing them twice. So, we'll do
1756 // them first (notice: most closures will ignore them anyway) and
1757 // then we'll do the "starts humongous" region.
1758 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1759 HeapRegion* chr = region_at(ch_index);
1761 // if the region has already been claimed or it's not
1762 // "continues humongous" we're done
1763 if (chr->claim_value() == claim_value ||
1764 !chr->continuesHumongous()) {
1765 break;
1766 }
1768 // Noone should have claimed it directly. We can given
1769 // that we claimed its "starts humongous" region.
1770 assert(chr->claim_value() != claim_value, "sanity");
1771 assert(chr->humongous_start_region() == r, "sanity");
1773 if (chr->claimHeapRegion(claim_value)) {
1774 // we should always be able to claim it; noone else should
1775 // be trying to claim this region
1777 bool res2 = cl->doHeapRegion(chr);
1778 assert(!res2, "Should not abort");
1780 // Right now, this holds (i.e., no closure that actually
1781 // does something with "continues humongous" regions
1782 // clears them). We might have to weaken it in the future,
1783 // but let's leave these two asserts here for extra safety.
1784 assert(chr->continuesHumongous(), "should still be the case");
1785 assert(chr->humongous_start_region() == r, "sanity");
1786 } else {
1787 guarantee(false, "we should not reach here");
1788 }
1789 }
1790 }
1792 assert(!r->continuesHumongous(), "sanity");
1793 bool res = cl->doHeapRegion(r);
1794 assert(!res, "Should not abort");
1795 }
1796 }
1797 }
1799 class ResetClaimValuesClosure: public HeapRegionClosure {
1800 public:
1801 bool doHeapRegion(HeapRegion* r) {
1802 r->set_claim_value(HeapRegion::InitialClaimValue);
1803 return false;
1804 }
1805 };
1807 void
1808 G1CollectedHeap::reset_heap_region_claim_values() {
1809 ResetClaimValuesClosure blk;
1810 heap_region_iterate(&blk);
1811 }
1813 #ifdef ASSERT
1814 // This checks whether all regions in the heap have the correct claim
1815 // value. I also piggy-backed on this a check to ensure that the
1816 // humongous_start_region() information on "continues humongous"
1817 // regions is correct.
1819 class CheckClaimValuesClosure : public HeapRegionClosure {
1820 private:
1821 jint _claim_value;
1822 size_t _failures;
1823 HeapRegion* _sh_region;
1824 public:
1825 CheckClaimValuesClosure(jint claim_value) :
1826 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1827 bool doHeapRegion(HeapRegion* r) {
1828 if (r->claim_value() != _claim_value) {
1829 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1830 "claim value = %d, should be %d",
1831 r->bottom(), r->end(), r->claim_value(),
1832 _claim_value);
1833 ++_failures;
1834 }
1835 if (!r->isHumongous()) {
1836 _sh_region = NULL;
1837 } else if (r->startsHumongous()) {
1838 _sh_region = r;
1839 } else if (r->continuesHumongous()) {
1840 if (r->humongous_start_region() != _sh_region) {
1841 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1842 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1843 r->bottom(), r->end(),
1844 r->humongous_start_region(),
1845 _sh_region);
1846 ++_failures;
1847 }
1848 }
1849 return false;
1850 }
1851 size_t failures() {
1852 return _failures;
1853 }
1854 };
1856 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
1857 CheckClaimValuesClosure cl(claim_value);
1858 heap_region_iterate(&cl);
1859 return cl.failures() == 0;
1860 }
1861 #endif // ASSERT
1863 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
1864 HeapRegion* r = g1_policy()->collection_set();
1865 while (r != NULL) {
1866 HeapRegion* next = r->next_in_collection_set();
1867 if (cl->doHeapRegion(r)) {
1868 cl->incomplete();
1869 return;
1870 }
1871 r = next;
1872 }
1873 }
1875 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
1876 HeapRegionClosure *cl) {
1877 assert(r->in_collection_set(),
1878 "Start region must be a member of the collection set.");
1879 HeapRegion* cur = r;
1880 while (cur != NULL) {
1881 HeapRegion* next = cur->next_in_collection_set();
1882 if (cl->doHeapRegion(cur) && false) {
1883 cl->incomplete();
1884 return;
1885 }
1886 cur = next;
1887 }
1888 cur = g1_policy()->collection_set();
1889 while (cur != r) {
1890 HeapRegion* next = cur->next_in_collection_set();
1891 if (cl->doHeapRegion(cur) && false) {
1892 cl->incomplete();
1893 return;
1894 }
1895 cur = next;
1896 }
1897 }
1899 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
1900 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
1901 }
1904 Space* G1CollectedHeap::space_containing(const void* addr) const {
1905 Space* res = heap_region_containing(addr);
1906 if (res == NULL)
1907 res = perm_gen()->space_containing(addr);
1908 return res;
1909 }
1911 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
1912 Space* sp = space_containing(addr);
1913 if (sp != NULL) {
1914 return sp->block_start(addr);
1915 }
1916 return NULL;
1917 }
1919 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
1920 Space* sp = space_containing(addr);
1921 assert(sp != NULL, "block_size of address outside of heap");
1922 return sp->block_size(addr);
1923 }
1925 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
1926 Space* sp = space_containing(addr);
1927 return sp->block_is_obj(addr);
1928 }
1930 bool G1CollectedHeap::supports_tlab_allocation() const {
1931 return true;
1932 }
1934 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
1935 return HeapRegion::GrainBytes;
1936 }
1938 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
1939 // Return the remaining space in the cur alloc region, but not less than
1940 // the min TLAB size.
1941 // Also, no more than half the region size, since we can't allow tlabs to
1942 // grow big enough to accomodate humongous objects.
1944 // We need to story it locally, since it might change between when we
1945 // test for NULL and when we use it later.
1946 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
1947 if (cur_alloc_space == NULL) {
1948 return HeapRegion::GrainBytes/2;
1949 } else {
1950 return MAX2(MIN2(cur_alloc_space->free(),
1951 (size_t)(HeapRegion::GrainBytes/2)),
1952 (size_t)MinTLABSize);
1953 }
1954 }
1956 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
1957 bool dummy;
1958 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
1959 }
1961 bool G1CollectedHeap::allocs_are_zero_filled() {
1962 return false;
1963 }
1965 size_t G1CollectedHeap::large_typearray_limit() {
1966 // FIXME
1967 return HeapRegion::GrainBytes/HeapWordSize;
1968 }
1970 size_t G1CollectedHeap::max_capacity() const {
1971 return _g1_committed.byte_size();
1972 }
1974 jlong G1CollectedHeap::millis_since_last_gc() {
1975 // assert(false, "NYI");
1976 return 0;
1977 }
1980 void G1CollectedHeap::prepare_for_verify() {
1981 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1982 ensure_parsability(false);
1983 }
1984 g1_rem_set()->prepare_for_verify();
1985 }
1987 class VerifyLivenessOopClosure: public OopClosure {
1988 G1CollectedHeap* g1h;
1989 public:
1990 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
1991 g1h = _g1h;
1992 }
1993 void do_oop(narrowOop *p) {
1994 guarantee(false, "NYI");
1995 }
1996 void do_oop(oop *p) {
1997 oop obj = *p;
1998 assert(obj == NULL || !g1h->is_obj_dead(obj),
1999 "Dead object referenced by a not dead object");
2000 }
2001 };
2003 class VerifyObjsInRegionClosure: public ObjectClosure {
2004 G1CollectedHeap* _g1h;
2005 size_t _live_bytes;
2006 HeapRegion *_hr;
2007 public:
2008 VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) {
2009 _g1h = G1CollectedHeap::heap();
2010 }
2011 void do_object(oop o) {
2012 VerifyLivenessOopClosure isLive(_g1h);
2013 assert(o != NULL, "Huh?");
2014 if (!_g1h->is_obj_dead(o)) {
2015 o->oop_iterate(&isLive);
2016 if (!_hr->obj_allocated_since_prev_marking(o))
2017 _live_bytes += (o->size() * HeapWordSize);
2018 }
2019 }
2020 size_t live_bytes() { return _live_bytes; }
2021 };
2023 class PrintObjsInRegionClosure : public ObjectClosure {
2024 HeapRegion *_hr;
2025 G1CollectedHeap *_g1;
2026 public:
2027 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2028 _g1 = G1CollectedHeap::heap();
2029 };
2031 void do_object(oop o) {
2032 if (o != NULL) {
2033 HeapWord *start = (HeapWord *) o;
2034 size_t word_sz = o->size();
2035 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2036 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2037 (void*) o, word_sz,
2038 _g1->isMarkedPrev(o),
2039 _g1->isMarkedNext(o),
2040 _hr->obj_allocated_since_prev_marking(o));
2041 HeapWord *end = start + word_sz;
2042 HeapWord *cur;
2043 int *val;
2044 for (cur = start; cur < end; cur++) {
2045 val = (int *) cur;
2046 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2047 }
2048 }
2049 }
2050 };
2052 class VerifyRegionClosure: public HeapRegionClosure {
2053 public:
2054 bool _allow_dirty;
2055 bool _par;
2056 VerifyRegionClosure(bool allow_dirty, bool par = false)
2057 : _allow_dirty(allow_dirty), _par(par) {}
2058 bool doHeapRegion(HeapRegion* r) {
2059 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2060 "Should be unclaimed at verify points.");
2061 if (r->isHumongous()) {
2062 if (r->startsHumongous()) {
2063 // Verify the single H object.
2064 oop(r->bottom())->verify();
2065 size_t word_sz = oop(r->bottom())->size();
2066 guarantee(r->top() == r->bottom() + word_sz,
2067 "Only one object in a humongous region");
2068 }
2069 } else {
2070 VerifyObjsInRegionClosure not_dead_yet_cl(r);
2071 r->verify(_allow_dirty);
2072 r->object_iterate(¬_dead_yet_cl);
2073 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2074 "More live objects than counted in last complete marking.");
2075 }
2076 return false;
2077 }
2078 };
2080 class VerifyRootsClosure: public OopsInGenClosure {
2081 private:
2082 G1CollectedHeap* _g1h;
2083 bool _failures;
2085 public:
2086 VerifyRootsClosure() :
2087 _g1h(G1CollectedHeap::heap()), _failures(false) { }
2089 bool failures() { return _failures; }
2091 void do_oop(narrowOop* p) {
2092 guarantee(false, "NYI");
2093 }
2095 void do_oop(oop* p) {
2096 oop obj = *p;
2097 if (obj != NULL) {
2098 if (_g1h->is_obj_dead(obj)) {
2099 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2100 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2101 obj->print_on(gclog_or_tty);
2102 _failures = true;
2103 }
2104 }
2105 }
2106 };
2108 // This is the task used for parallel heap verification.
2110 class G1ParVerifyTask: public AbstractGangTask {
2111 private:
2112 G1CollectedHeap* _g1h;
2113 bool _allow_dirty;
2115 public:
2116 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) :
2117 AbstractGangTask("Parallel verify task"),
2118 _g1h(g1h), _allow_dirty(allow_dirty) { }
2120 void work(int worker_i) {
2121 VerifyRegionClosure blk(_allow_dirty, true);
2122 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2123 HeapRegion::ParVerifyClaimValue);
2124 }
2125 };
2127 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2128 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2129 if (!silent) { gclog_or_tty->print("roots "); }
2130 VerifyRootsClosure rootsCl;
2131 process_strong_roots(false,
2132 SharedHeap::SO_AllClasses,
2133 &rootsCl,
2134 &rootsCl);
2135 rem_set()->invalidate(perm_gen()->used_region(), false);
2136 if (!silent) { gclog_or_tty->print("heapRegions "); }
2137 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2138 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2139 "sanity check");
2141 G1ParVerifyTask task(this, allow_dirty);
2142 int n_workers = workers()->total_workers();
2143 set_par_threads(n_workers);
2144 workers()->run_task(&task);
2145 set_par_threads(0);
2147 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2148 "sanity check");
2150 reset_heap_region_claim_values();
2152 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2153 "sanity check");
2154 } else {
2155 VerifyRegionClosure blk(allow_dirty);
2156 _hrs->iterate(&blk);
2157 }
2158 if (!silent) gclog_or_tty->print("remset ");
2159 rem_set()->verify();
2160 guarantee(!rootsCl.failures(), "should not have had failures");
2161 } else {
2162 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2163 }
2164 }
2166 class PrintRegionClosure: public HeapRegionClosure {
2167 outputStream* _st;
2168 public:
2169 PrintRegionClosure(outputStream* st) : _st(st) {}
2170 bool doHeapRegion(HeapRegion* r) {
2171 r->print_on(_st);
2172 return false;
2173 }
2174 };
2176 void G1CollectedHeap::print() const { print_on(gclog_or_tty); }
2178 void G1CollectedHeap::print_on(outputStream* st) const {
2179 PrintRegionClosure blk(st);
2180 _hrs->iterate(&blk);
2181 }
2183 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2184 if (ParallelGCThreads > 0) {
2185 workers()->print_worker_threads();
2186 }
2187 st->print("\"G1 concurrent mark GC Thread\" ");
2188 _cmThread->print();
2189 st->cr();
2190 st->print("\"G1 concurrent refinement GC Thread\" ");
2191 _cg1r->cg1rThread()->print_on(st);
2192 st->cr();
2193 st->print("\"G1 zero-fill GC Thread\" ");
2194 _czft->print_on(st);
2195 st->cr();
2196 }
2198 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2199 if (ParallelGCThreads > 0) {
2200 workers()->threads_do(tc);
2201 }
2202 tc->do_thread(_cmThread);
2203 tc->do_thread(_cg1r->cg1rThread());
2204 tc->do_thread(_czft);
2205 }
2207 void G1CollectedHeap::print_tracing_info() const {
2208 concurrent_g1_refine()->print_final_card_counts();
2210 // We'll overload this to mean "trace GC pause statistics."
2211 if (TraceGen0Time || TraceGen1Time) {
2212 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2213 // to that.
2214 g1_policy()->print_tracing_info();
2215 }
2216 if (SummarizeG1RSStats) {
2217 g1_rem_set()->print_summary_info();
2218 }
2219 if (SummarizeG1ConcMark) {
2220 concurrent_mark()->print_summary_info();
2221 }
2222 if (SummarizeG1ZFStats) {
2223 ConcurrentZFThread::print_summary_info();
2224 }
2225 if (G1SummarizePopularity) {
2226 print_popularity_summary_info();
2227 }
2228 g1_policy()->print_yg_surv_rate_info();
2230 GCOverheadReporter::printGCOverhead();
2232 SpecializationStats::print();
2233 }
2236 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2237 HeapRegion* hr = heap_region_containing(addr);
2238 if (hr == NULL) {
2239 return 0;
2240 } else {
2241 return 1;
2242 }
2243 }
2245 G1CollectedHeap* G1CollectedHeap::heap() {
2246 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2247 "not a garbage-first heap");
2248 return _g1h;
2249 }
2251 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2252 if (PrintHeapAtGC){
2253 gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections());
2254 Universe::print();
2255 }
2256 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2257 // Call allocation profiler
2258 AllocationProfiler::iterate_since_last_gc();
2259 // Fill TLAB's and such
2260 ensure_parsability(true);
2261 }
2263 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2264 // FIXME: what is this about?
2265 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2266 // is set.
2267 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2268 "derived pointer present"));
2270 if (PrintHeapAtGC){
2271 gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections());
2272 Universe::print();
2273 gclog_or_tty->print("} ");
2274 }
2275 }
2277 void G1CollectedHeap::do_collection_pause() {
2278 // Read the GC count while holding the Heap_lock
2279 // we need to do this _before_ wait_for_cleanup_complete(), to
2280 // ensure that we do not give up the heap lock and potentially
2281 // pick up the wrong count
2282 int gc_count_before = SharedHeap::heap()->total_collections();
2284 // Don't want to do a GC pause while cleanup is being completed!
2285 wait_for_cleanup_complete();
2287 g1_policy()->record_stop_world_start();
2288 {
2289 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2290 VM_G1IncCollectionPause op(gc_count_before);
2291 VMThread::execute(&op);
2292 }
2293 }
2295 void
2296 G1CollectedHeap::doConcurrentMark() {
2297 if (G1ConcMark) {
2298 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2299 if (!_cmThread->in_progress()) {
2300 _cmThread->set_started();
2301 CGC_lock->notify();
2302 }
2303 }
2304 }
2306 class VerifyMarkedObjsClosure: public ObjectClosure {
2307 G1CollectedHeap* _g1h;
2308 public:
2309 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2310 void do_object(oop obj) {
2311 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2312 "markandsweep mark should agree with concurrent deadness");
2313 }
2314 };
2316 void
2317 G1CollectedHeap::checkConcurrentMark() {
2318 VerifyMarkedObjsClosure verifycl(this);
2319 doConcurrentMark();
2320 // MutexLockerEx x(getMarkBitMapLock(),
2321 // Mutex::_no_safepoint_check_flag);
2322 object_iterate(&verifycl);
2323 }
2325 void G1CollectedHeap::do_sync_mark() {
2326 _cm->checkpointRootsInitial();
2327 _cm->markFromRoots();
2328 _cm->checkpointRootsFinal(false);
2329 }
2331 // <NEW PREDICTION>
2333 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2334 bool young) {
2335 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2336 }
2338 void G1CollectedHeap::check_if_region_is_too_expensive(double
2339 predicted_time_ms) {
2340 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2341 }
2343 size_t G1CollectedHeap::pending_card_num() {
2344 size_t extra_cards = 0;
2345 JavaThread *curr = Threads::first();
2346 while (curr != NULL) {
2347 DirtyCardQueue& dcq = curr->dirty_card_queue();
2348 extra_cards += dcq.size();
2349 curr = curr->next();
2350 }
2351 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2352 size_t buffer_size = dcqs.buffer_size();
2353 size_t buffer_num = dcqs.completed_buffers_num();
2354 return buffer_size * buffer_num + extra_cards;
2355 }
2357 size_t G1CollectedHeap::max_pending_card_num() {
2358 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2359 size_t buffer_size = dcqs.buffer_size();
2360 size_t buffer_num = dcqs.completed_buffers_num();
2361 int thread_num = Threads::number_of_threads();
2362 return (buffer_num + thread_num) * buffer_size;
2363 }
2365 size_t G1CollectedHeap::cards_scanned() {
2366 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2367 return g1_rset->cardsScanned();
2368 }
2370 void
2371 G1CollectedHeap::setup_surviving_young_words() {
2372 guarantee( _surviving_young_words == NULL, "pre-condition" );
2373 size_t array_length = g1_policy()->young_cset_length();
2374 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2375 if (_surviving_young_words == NULL) {
2376 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2377 "Not enough space for young surv words summary.");
2378 }
2379 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2380 for (size_t i = 0; i < array_length; ++i) {
2381 guarantee( _surviving_young_words[i] == 0, "invariant" );
2382 }
2383 }
2385 void
2386 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2387 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2388 size_t array_length = g1_policy()->young_cset_length();
2389 for (size_t i = 0; i < array_length; ++i)
2390 _surviving_young_words[i] += surv_young_words[i];
2391 }
2393 void
2394 G1CollectedHeap::cleanup_surviving_young_words() {
2395 guarantee( _surviving_young_words != NULL, "pre-condition" );
2396 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2397 _surviving_young_words = NULL;
2398 }
2400 // </NEW PREDICTION>
2402 void
2403 G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) {
2404 char verbose_str[128];
2405 sprintf(verbose_str, "GC pause ");
2406 if (popular_region != NULL)
2407 strcat(verbose_str, "(popular)");
2408 else if (g1_policy()->in_young_gc_mode()) {
2409 if (g1_policy()->full_young_gcs())
2410 strcat(verbose_str, "(young)");
2411 else
2412 strcat(verbose_str, "(partial)");
2413 }
2414 bool reset_should_initiate_conc_mark = false;
2415 if (popular_region != NULL && g1_policy()->should_initiate_conc_mark()) {
2416 // we currently do not allow an initial mark phase to be piggy-backed
2417 // on a popular pause
2418 reset_should_initiate_conc_mark = true;
2419 g1_policy()->unset_should_initiate_conc_mark();
2420 }
2421 if (g1_policy()->should_initiate_conc_mark())
2422 strcat(verbose_str, " (initial-mark)");
2424 GCCauseSetter x(this, (popular_region == NULL ?
2425 GCCause::_g1_inc_collection_pause :
2426 GCCause::_g1_pop_region_collection_pause));
2428 // if PrintGCDetails is on, we'll print long statistics information
2429 // in the collector policy code, so let's not print this as the output
2430 // is messy if we do.
2431 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2432 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2433 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2435 ResourceMark rm;
2436 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2437 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2438 guarantee(!is_gc_active(), "collection is not reentrant");
2439 assert(regions_accounted_for(), "Region leakage!");
2441 increment_gc_time_stamp();
2443 if (g1_policy()->in_young_gc_mode()) {
2444 assert(check_young_list_well_formed(),
2445 "young list should be well formed");
2446 }
2448 if (GC_locker::is_active()) {
2449 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2450 }
2452 bool abandoned = false;
2453 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2454 IsGCActiveMark x;
2456 gc_prologue(false);
2457 increment_total_collections();
2459 #if G1_REM_SET_LOGGING
2460 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2461 print();
2462 #endif
2464 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2465 HandleMark hm; // Discard invalid handles created during verification
2466 prepare_for_verify();
2467 gclog_or_tty->print(" VerifyBeforeGC:");
2468 Universe::verify(false);
2469 }
2471 COMPILER2_PRESENT(DerivedPointerTable::clear());
2473 // We want to turn off ref discovery, if necessary, and turn it back on
2474 // on again later if we do.
2475 bool was_enabled = ref_processor()->discovery_enabled();
2476 if (was_enabled) ref_processor()->disable_discovery();
2478 // Forget the current alloc region (we might even choose it to be part
2479 // of the collection set!).
2480 abandon_cur_alloc_region();
2482 // The elapsed time induced by the start time below deliberately elides
2483 // the possible verification above.
2484 double start_time_sec = os::elapsedTime();
2485 GCOverheadReporter::recordSTWStart(start_time_sec);
2486 size_t start_used_bytes = used();
2487 if (!G1ConcMark) {
2488 do_sync_mark();
2489 }
2491 g1_policy()->record_collection_pause_start(start_time_sec,
2492 start_used_bytes);
2494 guarantee(_in_cset_fast_test == NULL, "invariant");
2495 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2496 _in_cset_fast_test_length = n_regions();
2497 _in_cset_fast_test_base =
2498 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2499 memset(_in_cset_fast_test_base, false,
2500 _in_cset_fast_test_length * sizeof(bool));
2501 // We're biasing _in_cset_fast_test to avoid subtracting the
2502 // beginning of the heap every time we want to index; basically
2503 // it's the same with what we do with the card table.
2504 _in_cset_fast_test = _in_cset_fast_test_base -
2505 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2507 #if SCAN_ONLY_VERBOSE
2508 _young_list->print();
2509 #endif // SCAN_ONLY_VERBOSE
2511 if (g1_policy()->should_initiate_conc_mark()) {
2512 concurrent_mark()->checkpointRootsInitialPre();
2513 }
2514 save_marks();
2516 // We must do this before any possible evacuation that should propagate
2517 // marks, including evacuation of popular objects in a popular pause.
2518 if (mark_in_progress()) {
2519 double start_time_sec = os::elapsedTime();
2521 _cm->drainAllSATBBuffers();
2522 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2523 g1_policy()->record_satb_drain_time(finish_mark_ms);
2525 }
2526 // Record the number of elements currently on the mark stack, so we
2527 // only iterate over these. (Since evacuation may add to the mark
2528 // stack, doing more exposes race conditions.) If no mark is in
2529 // progress, this will be zero.
2530 _cm->set_oops_do_bound();
2532 assert(regions_accounted_for(), "Region leakage.");
2534 bool abandoned = false;
2536 if (mark_in_progress())
2537 concurrent_mark()->newCSet();
2539 // Now choose the CS.
2540 if (popular_region == NULL) {
2541 g1_policy()->choose_collection_set();
2542 } else {
2543 // We may be evacuating a single region (for popularity).
2544 g1_policy()->record_popular_pause_preamble_start();
2545 popularity_pause_preamble(popular_region);
2546 g1_policy()->record_popular_pause_preamble_end();
2547 abandoned = (g1_policy()->collection_set() == NULL);
2548 // Now we allow more regions to be added (we have to collect
2549 // all popular regions).
2550 if (!abandoned) {
2551 g1_policy()->choose_collection_set(popular_region);
2552 }
2553 }
2554 // We may abandon a pause if we find no region that will fit in the MMU
2555 // pause.
2556 abandoned = (g1_policy()->collection_set() == NULL);
2558 // Nothing to do if we were unable to choose a collection set.
2559 if (!abandoned) {
2560 #if G1_REM_SET_LOGGING
2561 gclog_or_tty->print_cr("\nAfter pause, heap:");
2562 print();
2563 #endif
2565 setup_surviving_young_words();
2567 // Set up the gc allocation regions.
2568 get_gc_alloc_regions();
2570 // Actually do the work...
2571 evacuate_collection_set();
2572 free_collection_set(g1_policy()->collection_set());
2573 g1_policy()->clear_collection_set();
2575 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2576 // this is more for peace of mind; we're nulling them here and
2577 // we're expecting them to be null at the beginning of the next GC
2578 _in_cset_fast_test = NULL;
2579 _in_cset_fast_test_base = NULL;
2581 if (popular_region != NULL) {
2582 // We have to wait until now, because we don't want the region to
2583 // be rescheduled for pop-evac during RS update.
2584 popular_region->set_popular_pending(false);
2585 }
2587 release_gc_alloc_regions();
2589 cleanup_surviving_young_words();
2591 if (g1_policy()->in_young_gc_mode()) {
2592 _young_list->reset_sampled_info();
2593 assert(check_young_list_empty(true),
2594 "young list should be empty");
2596 #if SCAN_ONLY_VERBOSE
2597 _young_list->print();
2598 #endif // SCAN_ONLY_VERBOSE
2600 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2601 _young_list->first_survivor_region(),
2602 _young_list->last_survivor_region());
2603 _young_list->reset_auxilary_lists();
2604 }
2605 } else {
2606 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2607 }
2609 if (evacuation_failed()) {
2610 _summary_bytes_used = recalculate_used();
2611 } else {
2612 // The "used" of the the collection set have already been subtracted
2613 // when they were freed. Add in the bytes evacuated.
2614 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2615 }
2617 if (g1_policy()->in_young_gc_mode() &&
2618 g1_policy()->should_initiate_conc_mark()) {
2619 concurrent_mark()->checkpointRootsInitialPost();
2620 set_marking_started();
2621 doConcurrentMark();
2622 }
2624 #if SCAN_ONLY_VERBOSE
2625 _young_list->print();
2626 #endif // SCAN_ONLY_VERBOSE
2628 double end_time_sec = os::elapsedTime();
2629 if (!evacuation_failed()) {
2630 g1_policy()->record_pause_time((end_time_sec - start_time_sec)*1000.0);
2631 }
2632 GCOverheadReporter::recordSTWEnd(end_time_sec);
2633 g1_policy()->record_collection_pause_end(popular_region != NULL,
2634 abandoned);
2636 assert(regions_accounted_for(), "Region leakage.");
2638 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2639 HandleMark hm; // Discard invalid handles created during verification
2640 gclog_or_tty->print(" VerifyAfterGC:");
2641 Universe::verify(false);
2642 }
2644 if (was_enabled) ref_processor()->enable_discovery();
2646 {
2647 size_t expand_bytes = g1_policy()->expansion_amount();
2648 if (expand_bytes > 0) {
2649 size_t bytes_before = capacity();
2650 expand(expand_bytes);
2651 }
2652 }
2654 if (mark_in_progress()) {
2655 concurrent_mark()->update_g1_committed();
2656 }
2658 #ifdef TRACESPINNING
2659 ParallelTaskTerminator::print_termination_counts();
2660 #endif
2662 gc_epilogue(false);
2663 }
2665 assert(verify_region_lists(), "Bad region lists.");
2667 if (reset_should_initiate_conc_mark)
2668 g1_policy()->set_should_initiate_conc_mark();
2670 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2671 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2672 print_tracing_info();
2673 vm_exit(-1);
2674 }
2675 }
2677 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2678 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2679 HeapWord* original_top = NULL;
2680 if (r != NULL)
2681 original_top = r->top();
2683 // We will want to record the used space in r as being there before gc.
2684 // One we install it as a GC alloc region it's eligible for allocation.
2685 // So record it now and use it later.
2686 size_t r_used = 0;
2687 if (r != NULL) {
2688 r_used = r->used();
2690 if (ParallelGCThreads > 0) {
2691 // need to take the lock to guard against two threads calling
2692 // get_gc_alloc_region concurrently (very unlikely but...)
2693 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2694 r->save_marks();
2695 }
2696 }
2697 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2698 _gc_alloc_regions[purpose] = r;
2699 if (old_alloc_region != NULL) {
2700 // Replace aliases too.
2701 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2702 if (_gc_alloc_regions[ap] == old_alloc_region) {
2703 _gc_alloc_regions[ap] = r;
2704 }
2705 }
2706 }
2707 if (r != NULL) {
2708 push_gc_alloc_region(r);
2709 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2710 // We are using a region as a GC alloc region after it has been used
2711 // as a mutator allocation region during the current marking cycle.
2712 // The mutator-allocated objects are currently implicitly marked, but
2713 // when we move hr->next_top_at_mark_start() forward at the the end
2714 // of the GC pause, they won't be. We therefore mark all objects in
2715 // the "gap". We do this object-by-object, since marking densely
2716 // does not currently work right with marking bitmap iteration. This
2717 // means we rely on TLAB filling at the start of pauses, and no
2718 // "resuscitation" of filled TLAB's. If we want to do this, we need
2719 // to fix the marking bitmap iteration.
2720 HeapWord* curhw = r->next_top_at_mark_start();
2721 HeapWord* t = original_top;
2723 while (curhw < t) {
2724 oop cur = (oop)curhw;
2725 // We'll assume parallel for generality. This is rare code.
2726 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2727 curhw = curhw + cur->size();
2728 }
2729 assert(curhw == t, "Should have parsed correctly.");
2730 }
2731 if (G1PolicyVerbose > 1) {
2732 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2733 "for survivors:", r->bottom(), original_top, r->end());
2734 r->print();
2735 }
2736 g1_policy()->record_before_bytes(r_used);
2737 }
2738 }
2740 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2741 assert(Thread::current()->is_VM_thread() ||
2742 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2743 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2744 "Precondition.");
2745 hr->set_is_gc_alloc_region(true);
2746 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2747 _gc_alloc_region_list = hr;
2748 }
2750 #ifdef G1_DEBUG
2751 class FindGCAllocRegion: public HeapRegionClosure {
2752 public:
2753 bool doHeapRegion(HeapRegion* r) {
2754 if (r->is_gc_alloc_region()) {
2755 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2756 r->hrs_index(), r->bottom());
2757 }
2758 return false;
2759 }
2760 };
2761 #endif // G1_DEBUG
2763 void G1CollectedHeap::forget_alloc_region_list() {
2764 assert(Thread::current()->is_VM_thread(), "Precondition");
2765 while (_gc_alloc_region_list != NULL) {
2766 HeapRegion* r = _gc_alloc_region_list;
2767 assert(r->is_gc_alloc_region(), "Invariant.");
2768 _gc_alloc_region_list = r->next_gc_alloc_region();
2769 r->set_next_gc_alloc_region(NULL);
2770 r->set_is_gc_alloc_region(false);
2771 if (r->is_survivor()) {
2772 if (r->is_empty()) {
2773 r->set_not_young();
2774 } else {
2775 _young_list->add_survivor_region(r);
2776 }
2777 }
2778 if (r->is_empty()) {
2779 ++_free_regions;
2780 }
2781 }
2782 #ifdef G1_DEBUG
2783 FindGCAllocRegion fa;
2784 heap_region_iterate(&fa);
2785 #endif // G1_DEBUG
2786 }
2789 bool G1CollectedHeap::check_gc_alloc_regions() {
2790 // TODO: allocation regions check
2791 return true;
2792 }
2794 void G1CollectedHeap::get_gc_alloc_regions() {
2795 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2796 // Create new GC alloc regions.
2797 HeapRegion* alloc_region = _gc_alloc_regions[ap];
2798 // Clear this alloc region, so that in case it turns out to be
2799 // unacceptable, we end up with no allocation region, rather than a bad
2800 // one.
2801 _gc_alloc_regions[ap] = NULL;
2802 if (alloc_region == NULL || alloc_region->in_collection_set()) {
2803 // Can't re-use old one. Allocate a new one.
2804 alloc_region = newAllocRegionWithExpansion(ap, 0);
2805 }
2806 if (alloc_region != NULL) {
2807 set_gc_alloc_region(ap, alloc_region);
2808 }
2809 }
2810 // Set alternative regions for allocation purposes that have reached
2811 // thier limit.
2812 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2813 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
2814 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
2815 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
2816 }
2817 }
2818 assert(check_gc_alloc_regions(), "alloc regions messed up");
2819 }
2821 void G1CollectedHeap::release_gc_alloc_regions() {
2822 // We keep a separate list of all regions that have been alloc regions in
2823 // the current collection pause. Forget that now.
2824 forget_alloc_region_list();
2826 // The current alloc regions contain objs that have survived
2827 // collection. Make them no longer GC alloc regions.
2828 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2829 HeapRegion* r = _gc_alloc_regions[ap];
2830 if (r != NULL && r->is_empty()) {
2831 {
2832 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
2833 r->set_zero_fill_complete();
2834 put_free_region_on_list_locked(r);
2835 }
2836 }
2837 // set_gc_alloc_region will also NULLify all aliases to the region
2838 set_gc_alloc_region(ap, NULL);
2839 _gc_alloc_region_counts[ap] = 0;
2840 }
2841 }
2843 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
2844 _drain_in_progress = false;
2845 set_evac_failure_closure(cl);
2846 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
2847 }
2849 void G1CollectedHeap::finalize_for_evac_failure() {
2850 assert(_evac_failure_scan_stack != NULL &&
2851 _evac_failure_scan_stack->length() == 0,
2852 "Postcondition");
2853 assert(!_drain_in_progress, "Postcondition");
2854 // Don't have to delete, since the scan stack is a resource object.
2855 _evac_failure_scan_stack = NULL;
2856 }
2860 // *** Sequential G1 Evacuation
2862 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
2863 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
2864 // let the caller handle alloc failure
2865 if (alloc_region == NULL) return NULL;
2866 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
2867 "Either the object is humongous or the region isn't");
2868 HeapWord* block = alloc_region->allocate(word_size);
2869 if (block == NULL) {
2870 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
2871 }
2872 return block;
2873 }
2875 class G1IsAliveClosure: public BoolObjectClosure {
2876 G1CollectedHeap* _g1;
2877 public:
2878 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2879 void do_object(oop p) { assert(false, "Do not call."); }
2880 bool do_object_b(oop p) {
2881 // It is reachable if it is outside the collection set, or is inside
2882 // and forwarded.
2884 #ifdef G1_DEBUG
2885 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
2886 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
2887 !_g1->obj_in_cs(p) || p->is_forwarded());
2888 #endif // G1_DEBUG
2890 return !_g1->obj_in_cs(p) || p->is_forwarded();
2891 }
2892 };
2894 class G1KeepAliveClosure: public OopClosure {
2895 G1CollectedHeap* _g1;
2896 public:
2897 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2898 void do_oop(narrowOop* p) {
2899 guarantee(false, "NYI");
2900 }
2901 void do_oop(oop* p) {
2902 oop obj = *p;
2903 #ifdef G1_DEBUG
2904 if (PrintGC && Verbose) {
2905 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
2906 p, (void*) obj, (void*) *p);
2907 }
2908 #endif // G1_DEBUG
2910 if (_g1->obj_in_cs(obj)) {
2911 assert( obj->is_forwarded(), "invariant" );
2912 *p = obj->forwardee();
2914 #ifdef G1_DEBUG
2915 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
2916 (void*) obj, (void*) *p);
2917 #endif // G1_DEBUG
2918 }
2919 }
2920 };
2922 class RecreateRSetEntriesClosure: public OopClosure {
2923 private:
2924 G1CollectedHeap* _g1;
2925 G1RemSet* _g1_rem_set;
2926 HeapRegion* _from;
2927 public:
2928 RecreateRSetEntriesClosure(G1CollectedHeap* g1, HeapRegion* from) :
2929 _g1(g1), _g1_rem_set(g1->g1_rem_set()), _from(from)
2930 {}
2932 void do_oop(narrowOop* p) {
2933 guarantee(false, "NYI");
2934 }
2935 void do_oop(oop* p) {
2936 assert(_from->is_in_reserved(p), "paranoia");
2937 if (*p != NULL) {
2938 _g1_rem_set->write_ref(_from, p);
2939 }
2940 }
2941 };
2943 class RemoveSelfPointerClosure: public ObjectClosure {
2944 private:
2945 G1CollectedHeap* _g1;
2946 ConcurrentMark* _cm;
2947 HeapRegion* _hr;
2948 size_t _prev_marked_bytes;
2949 size_t _next_marked_bytes;
2950 public:
2951 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr) :
2952 _g1(g1), _cm(_g1->concurrent_mark()), _hr(hr),
2953 _prev_marked_bytes(0), _next_marked_bytes(0)
2954 {}
2956 size_t prev_marked_bytes() { return _prev_marked_bytes; }
2957 size_t next_marked_bytes() { return _next_marked_bytes; }
2959 // The original idea here was to coalesce evacuated and dead objects.
2960 // However that caused complications with the block offset table (BOT).
2961 // In particular if there were two TLABs, one of them partially refined.
2962 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
2963 // The BOT entries of the unrefined part of TLAB_2 point to the start
2964 // of TLAB_2. If the last object of the TLAB_1 and the first object
2965 // of TLAB_2 are coalesced, then the cards of the unrefined part
2966 // would point into middle of the filler object.
2967 //
2968 // The current approach is to not coalesce and leave the BOT contents intact.
2969 void do_object(oop obj) {
2970 if (obj->is_forwarded() && obj->forwardee() == obj) {
2971 // The object failed to move.
2972 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
2973 _cm->markPrev(obj);
2974 assert(_cm->isPrevMarked(obj), "Should be marked!");
2975 _prev_marked_bytes += (obj->size() * HeapWordSize);
2976 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
2977 _cm->markAndGrayObjectIfNecessary(obj);
2978 }
2979 obj->set_mark(markOopDesc::prototype());
2980 // While we were processing RSet buffers during the
2981 // collection, we actually didn't scan any cards on the
2982 // collection set, since we didn't want to update remebered
2983 // sets with entries that point into the collection set, given
2984 // that live objects fromthe collection set are about to move
2985 // and such entries will be stale very soon. This change also
2986 // dealt with a reliability issue which involved scanning a
2987 // card in the collection set and coming across an array that
2988 // was being chunked and looking malformed. The problem is
2989 // that, if evacuation fails, we might have remembered set
2990 // entries missing given that we skipped cards on the
2991 // collection set. So, we'll recreate such entries now.
2992 RecreateRSetEntriesClosure cl(_g1, _hr);
2993 obj->oop_iterate(&cl);
2994 assert(_cm->isPrevMarked(obj), "Should be marked!");
2995 } else {
2996 // The object has been either evacuated or is dead. Fill it with a
2997 // dummy object.
2998 MemRegion mr((HeapWord*)obj, obj->size());
2999 CollectedHeap::fill_with_object(mr);
3000 _cm->clearRangeBothMaps(mr);
3001 }
3002 }
3003 };
3005 void G1CollectedHeap::remove_self_forwarding_pointers() {
3006 HeapRegion* cur = g1_policy()->collection_set();
3008 while (cur != NULL) {
3009 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3011 if (cur->evacuation_failed()) {
3012 RemoveSelfPointerClosure rspc(_g1h, cur);
3013 assert(cur->in_collection_set(), "bad CS");
3014 cur->object_iterate(&rspc);
3016 // A number of manipulations to make the TAMS be the current top,
3017 // and the marked bytes be the ones observed in the iteration.
3018 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3019 // The comments below are the postconditions achieved by the
3020 // calls. Note especially the last such condition, which says that
3021 // the count of marked bytes has been properly restored.
3022 cur->note_start_of_marking(false);
3023 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3024 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3025 // _next_marked_bytes == prev_marked_bytes.
3026 cur->note_end_of_marking();
3027 // _prev_top_at_mark_start == top(),
3028 // _prev_marked_bytes == prev_marked_bytes
3029 }
3030 // If there is no mark in progress, we modified the _next variables
3031 // above needlessly, but harmlessly.
3032 if (_g1h->mark_in_progress()) {
3033 cur->note_start_of_marking(false);
3034 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3035 // _next_marked_bytes == next_marked_bytes.
3036 }
3038 // Now make sure the region has the right index in the sorted array.
3039 g1_policy()->note_change_in_marked_bytes(cur);
3040 }
3041 cur = cur->next_in_collection_set();
3042 }
3043 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3045 // Now restore saved marks, if any.
3046 if (_objs_with_preserved_marks != NULL) {
3047 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3048 assert(_objs_with_preserved_marks->length() ==
3049 _preserved_marks_of_objs->length(), "Both or none.");
3050 guarantee(_objs_with_preserved_marks->length() ==
3051 _preserved_marks_of_objs->length(), "Both or none.");
3052 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3053 oop obj = _objs_with_preserved_marks->at(i);
3054 markOop m = _preserved_marks_of_objs->at(i);
3055 obj->set_mark(m);
3056 }
3057 // Delete the preserved marks growable arrays (allocated on the C heap).
3058 delete _objs_with_preserved_marks;
3059 delete _preserved_marks_of_objs;
3060 _objs_with_preserved_marks = NULL;
3061 _preserved_marks_of_objs = NULL;
3062 }
3063 }
3065 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3066 _evac_failure_scan_stack->push(obj);
3067 }
3069 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3070 assert(_evac_failure_scan_stack != NULL, "precondition");
3072 while (_evac_failure_scan_stack->length() > 0) {
3073 oop obj = _evac_failure_scan_stack->pop();
3074 _evac_failure_closure->set_region(heap_region_containing(obj));
3075 obj->oop_iterate_backwards(_evac_failure_closure);
3076 }
3077 }
3079 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3080 markOop m = old->mark();
3081 // forward to self
3082 assert(!old->is_forwarded(), "precondition");
3084 old->forward_to(old);
3085 handle_evacuation_failure_common(old, m);
3086 }
3088 oop
3089 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3090 oop old) {
3091 markOop m = old->mark();
3092 oop forward_ptr = old->forward_to_atomic(old);
3093 if (forward_ptr == NULL) {
3094 // Forward-to-self succeeded.
3095 if (_evac_failure_closure != cl) {
3096 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3097 assert(!_drain_in_progress,
3098 "Should only be true while someone holds the lock.");
3099 // Set the global evac-failure closure to the current thread's.
3100 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3101 set_evac_failure_closure(cl);
3102 // Now do the common part.
3103 handle_evacuation_failure_common(old, m);
3104 // Reset to NULL.
3105 set_evac_failure_closure(NULL);
3106 } else {
3107 // The lock is already held, and this is recursive.
3108 assert(_drain_in_progress, "This should only be the recursive case.");
3109 handle_evacuation_failure_common(old, m);
3110 }
3111 return old;
3112 } else {
3113 // Someone else had a place to copy it.
3114 return forward_ptr;
3115 }
3116 }
3118 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3119 set_evacuation_failed(true);
3121 preserve_mark_if_necessary(old, m);
3123 HeapRegion* r = heap_region_containing(old);
3124 if (!r->evacuation_failed()) {
3125 r->set_evacuation_failed(true);
3126 if (G1TraceRegions) {
3127 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3128 "["PTR_FORMAT","PTR_FORMAT")\n",
3129 r, r->bottom(), r->end());
3130 }
3131 }
3133 push_on_evac_failure_scan_stack(old);
3135 if (!_drain_in_progress) {
3136 // prevent recursion in copy_to_survivor_space()
3137 _drain_in_progress = true;
3138 drain_evac_failure_scan_stack();
3139 _drain_in_progress = false;
3140 }
3141 }
3143 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3144 if (m != markOopDesc::prototype()) {
3145 if (_objs_with_preserved_marks == NULL) {
3146 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3147 _objs_with_preserved_marks =
3148 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3149 _preserved_marks_of_objs =
3150 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3151 }
3152 _objs_with_preserved_marks->push(obj);
3153 _preserved_marks_of_objs->push(m);
3154 }
3155 }
3157 // *** Parallel G1 Evacuation
3159 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3160 size_t word_size) {
3161 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3162 // let the caller handle alloc failure
3163 if (alloc_region == NULL) return NULL;
3165 HeapWord* block = alloc_region->par_allocate(word_size);
3166 if (block == NULL) {
3167 MutexLockerEx x(par_alloc_during_gc_lock(),
3168 Mutex::_no_safepoint_check_flag);
3169 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3170 }
3171 return block;
3172 }
3174 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3175 bool par) {
3176 // Another thread might have obtained alloc_region for the given
3177 // purpose, and might be attempting to allocate in it, and might
3178 // succeed. Therefore, we can't do the "finalization" stuff on the
3179 // region below until we're sure the last allocation has happened.
3180 // We ensure this by allocating the remaining space with a garbage
3181 // object.
3182 if (par) par_allocate_remaining_space(alloc_region);
3183 // Now we can do the post-GC stuff on the region.
3184 alloc_region->note_end_of_copying();
3185 g1_policy()->record_after_bytes(alloc_region->used());
3186 }
3188 HeapWord*
3189 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3190 HeapRegion* alloc_region,
3191 bool par,
3192 size_t word_size) {
3193 HeapWord* block = NULL;
3194 // In the parallel case, a previous thread to obtain the lock may have
3195 // already assigned a new gc_alloc_region.
3196 if (alloc_region != _gc_alloc_regions[purpose]) {
3197 assert(par, "But should only happen in parallel case.");
3198 alloc_region = _gc_alloc_regions[purpose];
3199 if (alloc_region == NULL) return NULL;
3200 block = alloc_region->par_allocate(word_size);
3201 if (block != NULL) return block;
3202 // Otherwise, continue; this new region is empty, too.
3203 }
3204 assert(alloc_region != NULL, "We better have an allocation region");
3205 retire_alloc_region(alloc_region, par);
3207 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3208 // Cannot allocate more regions for the given purpose.
3209 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3210 // Is there an alternative?
3211 if (purpose != alt_purpose) {
3212 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3213 // Has not the alternative region been aliased?
3214 if (alloc_region != alt_region && alt_region != NULL) {
3215 // Try to allocate in the alternative region.
3216 if (par) {
3217 block = alt_region->par_allocate(word_size);
3218 } else {
3219 block = alt_region->allocate(word_size);
3220 }
3221 // Make an alias.
3222 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3223 if (block != NULL) {
3224 return block;
3225 }
3226 retire_alloc_region(alt_region, par);
3227 }
3228 // Both the allocation region and the alternative one are full
3229 // and aliased, replace them with a new allocation region.
3230 purpose = alt_purpose;
3231 } else {
3232 set_gc_alloc_region(purpose, NULL);
3233 return NULL;
3234 }
3235 }
3237 // Now allocate a new region for allocation.
3238 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3240 // let the caller handle alloc failure
3241 if (alloc_region != NULL) {
3243 assert(check_gc_alloc_regions(), "alloc regions messed up");
3244 assert(alloc_region->saved_mark_at_top(),
3245 "Mark should have been saved already.");
3246 // We used to assert that the region was zero-filled here, but no
3247 // longer.
3249 // This must be done last: once it's installed, other regions may
3250 // allocate in it (without holding the lock.)
3251 set_gc_alloc_region(purpose, alloc_region);
3253 if (par) {
3254 block = alloc_region->par_allocate(word_size);
3255 } else {
3256 block = alloc_region->allocate(word_size);
3257 }
3258 // Caller handles alloc failure.
3259 } else {
3260 // This sets other apis using the same old alloc region to NULL, also.
3261 set_gc_alloc_region(purpose, NULL);
3262 }
3263 return block; // May be NULL.
3264 }
3266 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3267 HeapWord* block = NULL;
3268 size_t free_words;
3269 do {
3270 free_words = r->free()/HeapWordSize;
3271 // If there's too little space, no one can allocate, so we're done.
3272 if (free_words < (size_t)oopDesc::header_size()) return;
3273 // Otherwise, try to claim it.
3274 block = r->par_allocate(free_words);
3275 } while (block == NULL);
3276 fill_with_object(block, free_words);
3277 }
3279 #define use_local_bitmaps 1
3280 #define verify_local_bitmaps 0
3282 #ifndef PRODUCT
3284 class GCLabBitMap;
3285 class GCLabBitMapClosure: public BitMapClosure {
3286 private:
3287 ConcurrentMark* _cm;
3288 GCLabBitMap* _bitmap;
3290 public:
3291 GCLabBitMapClosure(ConcurrentMark* cm,
3292 GCLabBitMap* bitmap) {
3293 _cm = cm;
3294 _bitmap = bitmap;
3295 }
3297 virtual bool do_bit(size_t offset);
3298 };
3300 #endif // PRODUCT
3302 #define oop_buffer_length 256
3304 class GCLabBitMap: public BitMap {
3305 private:
3306 ConcurrentMark* _cm;
3308 int _shifter;
3309 size_t _bitmap_word_covers_words;
3311 // beginning of the heap
3312 HeapWord* _heap_start;
3314 // this is the actual start of the GCLab
3315 HeapWord* _real_start_word;
3317 // this is the actual end of the GCLab
3318 HeapWord* _real_end_word;
3320 // this is the first word, possibly located before the actual start
3321 // of the GCLab, that corresponds to the first bit of the bitmap
3322 HeapWord* _start_word;
3324 // size of a GCLab in words
3325 size_t _gclab_word_size;
3327 static int shifter() {
3328 return MinObjAlignment - 1;
3329 }
3331 // how many heap words does a single bitmap word corresponds to?
3332 static size_t bitmap_word_covers_words() {
3333 return BitsPerWord << shifter();
3334 }
3336 static size_t gclab_word_size() {
3337 return ParallelGCG1AllocBufferSize / HeapWordSize;
3338 }
3340 static size_t bitmap_size_in_bits() {
3341 size_t bits_in_bitmap = gclab_word_size() >> shifter();
3342 // We are going to ensure that the beginning of a word in this
3343 // bitmap also corresponds to the beginning of a word in the
3344 // global marking bitmap. To handle the case where a GCLab
3345 // starts from the middle of the bitmap, we need to add enough
3346 // space (i.e. up to a bitmap word) to ensure that we have
3347 // enough bits in the bitmap.
3348 return bits_in_bitmap + BitsPerWord - 1;
3349 }
3350 public:
3351 GCLabBitMap(HeapWord* heap_start)
3352 : BitMap(bitmap_size_in_bits()),
3353 _cm(G1CollectedHeap::heap()->concurrent_mark()),
3354 _shifter(shifter()),
3355 _bitmap_word_covers_words(bitmap_word_covers_words()),
3356 _heap_start(heap_start),
3357 _gclab_word_size(gclab_word_size()),
3358 _real_start_word(NULL),
3359 _real_end_word(NULL),
3360 _start_word(NULL)
3361 {
3362 guarantee( size_in_words() >= bitmap_size_in_words(),
3363 "just making sure");
3364 }
3366 inline unsigned heapWordToOffset(HeapWord* addr) {
3367 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
3368 assert(offset < size(), "offset should be within bounds");
3369 return offset;
3370 }
3372 inline HeapWord* offsetToHeapWord(size_t offset) {
3373 HeapWord* addr = _start_word + (offset << _shifter);
3374 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
3375 return addr;
3376 }
3378 bool fields_well_formed() {
3379 bool ret1 = (_real_start_word == NULL) &&
3380 (_real_end_word == NULL) &&
3381 (_start_word == NULL);
3382 if (ret1)
3383 return true;
3385 bool ret2 = _real_start_word >= _start_word &&
3386 _start_word < _real_end_word &&
3387 (_real_start_word + _gclab_word_size) == _real_end_word &&
3388 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
3389 > _real_end_word;
3390 return ret2;
3391 }
3393 inline bool mark(HeapWord* addr) {
3394 guarantee(use_local_bitmaps, "invariant");
3395 assert(fields_well_formed(), "invariant");
3397 if (addr >= _real_start_word && addr < _real_end_word) {
3398 assert(!isMarked(addr), "should not have already been marked");
3400 // first mark it on the bitmap
3401 at_put(heapWordToOffset(addr), true);
3403 return true;
3404 } else {
3405 return false;
3406 }
3407 }
3409 inline bool isMarked(HeapWord* addr) {
3410 guarantee(use_local_bitmaps, "invariant");
3411 assert(fields_well_formed(), "invariant");
3413 return at(heapWordToOffset(addr));
3414 }
3416 void set_buffer(HeapWord* start) {
3417 guarantee(use_local_bitmaps, "invariant");
3418 clear();
3420 assert(start != NULL, "invariant");
3421 _real_start_word = start;
3422 _real_end_word = start + _gclab_word_size;
3424 size_t diff =
3425 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
3426 _start_word = start - diff;
3428 assert(fields_well_formed(), "invariant");
3429 }
3431 #ifndef PRODUCT
3432 void verify() {
3433 // verify that the marks have been propagated
3434 GCLabBitMapClosure cl(_cm, this);
3435 iterate(&cl);
3436 }
3437 #endif // PRODUCT
3439 void retire() {
3440 guarantee(use_local_bitmaps, "invariant");
3441 assert(fields_well_formed(), "invariant");
3443 if (_start_word != NULL) {
3444 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
3446 // this means that the bitmap was set up for the GCLab
3447 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
3449 mark_bitmap->mostly_disjoint_range_union(this,
3450 0, // always start from the start of the bitmap
3451 _start_word,
3452 size_in_words());
3453 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
3455 #ifndef PRODUCT
3456 if (use_local_bitmaps && verify_local_bitmaps)
3457 verify();
3458 #endif // PRODUCT
3459 } else {
3460 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
3461 }
3462 }
3464 static size_t bitmap_size_in_words() {
3465 return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord;
3466 }
3467 };
3469 #ifndef PRODUCT
3471 bool GCLabBitMapClosure::do_bit(size_t offset) {
3472 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3473 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3474 return true;
3475 }
3477 #endif // PRODUCT
3479 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
3480 private:
3481 bool _retired;
3482 bool _during_marking;
3483 GCLabBitMap _bitmap;
3485 public:
3486 G1ParGCAllocBuffer() :
3487 ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize),
3488 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
3489 _bitmap(G1CollectedHeap::heap()->reserved_region().start()),
3490 _retired(false)
3491 { }
3493 inline bool mark(HeapWord* addr) {
3494 guarantee(use_local_bitmaps, "invariant");
3495 assert(_during_marking, "invariant");
3496 return _bitmap.mark(addr);
3497 }
3499 inline void set_buf(HeapWord* buf) {
3500 if (use_local_bitmaps && _during_marking)
3501 _bitmap.set_buffer(buf);
3502 ParGCAllocBuffer::set_buf(buf);
3503 _retired = false;
3504 }
3506 inline void retire(bool end_of_gc, bool retain) {
3507 if (_retired)
3508 return;
3509 if (use_local_bitmaps && _during_marking) {
3510 _bitmap.retire();
3511 }
3512 ParGCAllocBuffer::retire(end_of_gc, retain);
3513 _retired = true;
3514 }
3515 };
3518 class G1ParScanThreadState : public StackObj {
3519 protected:
3520 G1CollectedHeap* _g1h;
3521 RefToScanQueue* _refs;
3523 typedef GrowableArray<oop*> OverflowQueue;
3524 OverflowQueue* _overflowed_refs;
3526 G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount];
3527 ageTable _age_table;
3529 size_t _alloc_buffer_waste;
3530 size_t _undo_waste;
3532 OopsInHeapRegionClosure* _evac_failure_cl;
3533 G1ParScanHeapEvacClosure* _evac_cl;
3534 G1ParScanPartialArrayClosure* _partial_scan_cl;
3536 int _hash_seed;
3537 int _queue_num;
3539 int _term_attempts;
3540 #if G1_DETAILED_STATS
3541 int _pushes, _pops, _steals, _steal_attempts;
3542 int _overflow_pushes;
3543 #endif
3545 double _start;
3546 double _start_strong_roots;
3547 double _strong_roots_time;
3548 double _start_term;
3549 double _term_time;
3551 // Map from young-age-index (0 == not young, 1 is youngest) to
3552 // surviving words. base is what we get back from the malloc call
3553 size_t* _surviving_young_words_base;
3554 // this points into the array, as we use the first few entries for padding
3555 size_t* _surviving_young_words;
3557 #define PADDING_ELEM_NUM (64 / sizeof(size_t))
3559 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
3561 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
3563 public:
3564 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3565 : _g1h(g1h),
3566 _refs(g1h->task_queue(queue_num)),
3567 _hash_seed(17), _queue_num(queue_num),
3568 _term_attempts(0),
3569 _age_table(false),
3570 #if G1_DETAILED_STATS
3571 _pushes(0), _pops(0), _steals(0),
3572 _steal_attempts(0), _overflow_pushes(0),
3573 #endif
3574 _strong_roots_time(0), _term_time(0),
3575 _alloc_buffer_waste(0), _undo_waste(0)
3576 {
3577 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3578 // we "sacrifice" entry 0 to keep track of surviving bytes for
3579 // non-young regions (where the age is -1)
3580 // We also add a few elements at the beginning and at the end in
3581 // an attempt to eliminate cache contention
3582 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3583 size_t array_length = PADDING_ELEM_NUM +
3584 real_length +
3585 PADDING_ELEM_NUM;
3586 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3587 if (_surviving_young_words_base == NULL)
3588 vm_exit_out_of_memory(array_length * sizeof(size_t),
3589 "Not enough space for young surv histo.");
3590 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3591 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3593 _overflowed_refs = new OverflowQueue(10);
3595 _start = os::elapsedTime();
3596 }
3598 ~G1ParScanThreadState() {
3599 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
3600 }
3602 RefToScanQueue* refs() { return _refs; }
3603 OverflowQueue* overflowed_refs() { return _overflowed_refs; }
3604 ageTable* age_table() { return &_age_table; }
3606 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
3607 return &_alloc_buffers[purpose];
3608 }
3610 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
3611 size_t undo_waste() { return _undo_waste; }
3613 void push_on_queue(oop* ref) {
3614 assert(ref != NULL, "invariant");
3615 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant");
3617 if (!refs()->push(ref)) {
3618 overflowed_refs()->push(ref);
3619 IF_G1_DETAILED_STATS(note_overflow_push());
3620 } else {
3621 IF_G1_DETAILED_STATS(note_push());
3622 }
3623 }
3625 void pop_from_queue(oop*& ref) {
3626 if (!refs()->pop_local(ref)) {
3627 ref = NULL;
3628 } else {
3629 assert(ref != NULL, "invariant");
3630 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref),
3631 "invariant");
3633 IF_G1_DETAILED_STATS(note_pop());
3634 }
3635 }
3637 void pop_from_overflow_queue(oop*& ref) {
3638 ref = overflowed_refs()->pop();
3639 }
3641 int refs_to_scan() { return refs()->size(); }
3642 int overflowed_refs_to_scan() { return overflowed_refs()->length(); }
3644 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
3646 HeapWord* obj = NULL;
3647 if (word_sz * 100 <
3648 (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) *
3649 ParallelGCBufferWastePct) {
3650 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
3651 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
3652 alloc_buf->retire(false, false);
3654 HeapWord* buf =
3655 _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize);
3656 if (buf == NULL) return NULL; // Let caller handle allocation failure.
3657 // Otherwise.
3658 alloc_buf->set_buf(buf);
3660 obj = alloc_buf->allocate(word_sz);
3661 assert(obj != NULL, "buffer was definitely big enough...");
3662 } else {
3663 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
3664 }
3665 return obj;
3666 }
3668 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
3669 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
3670 if (obj != NULL) return obj;
3671 return allocate_slow(purpose, word_sz);
3672 }
3674 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
3675 if (alloc_buffer(purpose)->contains(obj)) {
3676 guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1),
3677 "should contain whole object");
3678 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
3679 } else {
3680 CollectedHeap::fill_with_object(obj, word_sz);
3681 add_to_undo_waste(word_sz);
3682 }
3683 }
3685 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
3686 _evac_failure_cl = evac_failure_cl;
3687 }
3688 OopsInHeapRegionClosure* evac_failure_closure() {
3689 return _evac_failure_cl;
3690 }
3692 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
3693 _evac_cl = evac_cl;
3694 }
3696 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
3697 _partial_scan_cl = partial_scan_cl;
3698 }
3700 int* hash_seed() { return &_hash_seed; }
3701 int queue_num() { return _queue_num; }
3703 int term_attempts() { return _term_attempts; }
3704 void note_term_attempt() { _term_attempts++; }
3706 #if G1_DETAILED_STATS
3707 int pushes() { return _pushes; }
3708 int pops() { return _pops; }
3709 int steals() { return _steals; }
3710 int steal_attempts() { return _steal_attempts; }
3711 int overflow_pushes() { return _overflow_pushes; }
3713 void note_push() { _pushes++; }
3714 void note_pop() { _pops++; }
3715 void note_steal() { _steals++; }
3716 void note_steal_attempt() { _steal_attempts++; }
3717 void note_overflow_push() { _overflow_pushes++; }
3718 #endif
3720 void start_strong_roots() {
3721 _start_strong_roots = os::elapsedTime();
3722 }
3723 void end_strong_roots() {
3724 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
3725 }
3726 double strong_roots_time() { return _strong_roots_time; }
3728 void start_term_time() {
3729 note_term_attempt();
3730 _start_term = os::elapsedTime();
3731 }
3732 void end_term_time() {
3733 _term_time += (os::elapsedTime() - _start_term);
3734 }
3735 double term_time() { return _term_time; }
3737 double elapsed() {
3738 return os::elapsedTime() - _start;
3739 }
3741 size_t* surviving_young_words() {
3742 // We add on to hide entry 0 which accumulates surviving words for
3743 // age -1 regions (i.e. non-young ones)
3744 return _surviving_young_words;
3745 }
3747 void retire_alloc_buffers() {
3748 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3749 size_t waste = _alloc_buffers[ap].words_remaining();
3750 add_to_alloc_buffer_waste(waste);
3751 _alloc_buffers[ap].retire(true, false);
3752 }
3753 }
3755 private:
3756 void deal_with_reference(oop* ref_to_scan) {
3757 if (has_partial_array_mask(ref_to_scan)) {
3758 _partial_scan_cl->do_oop_nv(ref_to_scan);
3759 } else {
3760 // Note: we can use "raw" versions of "region_containing" because
3761 // "obj_to_scan" is definitely in the heap, and is not in a
3762 // humongous region.
3763 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
3764 _evac_cl->set_region(r);
3765 _evac_cl->do_oop_nv(ref_to_scan);
3766 }
3767 }
3769 public:
3770 void trim_queue() {
3771 // I've replicated the loop twice, first to drain the overflow
3772 // queue, second to drain the task queue. This is better than
3773 // having a single loop, which checks both conditions and, inside
3774 // it, either pops the overflow queue or the task queue, as each
3775 // loop is tighter. Also, the decision to drain the overflow queue
3776 // first is not arbitrary, as the overflow queue is not visible
3777 // to the other workers, whereas the task queue is. So, we want to
3778 // drain the "invisible" entries first, while allowing the other
3779 // workers to potentially steal the "visible" entries.
3781 while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) {
3782 while (overflowed_refs_to_scan() > 0) {
3783 oop *ref_to_scan = NULL;
3784 pop_from_overflow_queue(ref_to_scan);
3785 assert(ref_to_scan != NULL, "invariant");
3786 // We shouldn't have pushed it on the queue if it was not
3787 // pointing into the CSet.
3788 assert(ref_to_scan != NULL, "sanity");
3789 assert(has_partial_array_mask(ref_to_scan) ||
3790 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3792 deal_with_reference(ref_to_scan);
3793 }
3795 while (refs_to_scan() > 0) {
3796 oop *ref_to_scan = NULL;
3797 pop_from_queue(ref_to_scan);
3799 if (ref_to_scan != NULL) {
3800 // We shouldn't have pushed it on the queue if it was not
3801 // pointing into the CSet.
3802 assert(has_partial_array_mask(ref_to_scan) ||
3803 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3805 deal_with_reference(ref_to_scan);
3806 }
3807 }
3808 }
3809 }
3810 };
3813 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3814 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3815 _par_scan_state(par_scan_state) { }
3817 // This closure is applied to the fields of the objects that have just been copied.
3818 // Should probably be made inline and moved in g1OopClosures.inline.hpp.
3819 void G1ParScanClosure::do_oop_nv(oop* p) {
3820 oop obj = *p;
3822 if (obj != NULL) {
3823 if (_g1->in_cset_fast_test(obj)) {
3824 // We're not going to even bother checking whether the object is
3825 // already forwarded or not, as this usually causes an immediate
3826 // stall. We'll try to prefetch the object (for write, given that
3827 // we might need to install the forwarding reference) and we'll
3828 // get back to it when pop it from the queue
3829 Prefetch::write(obj->mark_addr(), 0);
3830 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
3832 // slightly paranoid test; I'm trying to catch potential
3833 // problems before we go into push_on_queue to know where the
3834 // problem is coming from
3835 assert(obj == *p, "the value of *p should not have changed");
3836 _par_scan_state->push_on_queue(p);
3837 } else {
3838 _g1_rem->par_write_ref(_from, p, _par_scan_state->queue_num());
3839 }
3840 }
3841 }
3843 void G1ParCopyHelper::mark_forwardee(oop* p) {
3844 // This is called _after_ do_oop_work has been called, hence after
3845 // the object has been relocated to its new location and *p points
3846 // to its new location.
3848 oop thisOop = *p;
3849 if (thisOop != NULL) {
3850 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)),
3851 "shouldn't still be in the CSet if evacuation didn't fail.");
3852 HeapWord* addr = (HeapWord*)thisOop;
3853 if (_g1->is_in_g1_reserved(addr))
3854 _cm->grayRoot(oop(addr));
3855 }
3856 }
3858 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3859 size_t word_sz = old->size();
3860 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3861 // +1 to make the -1 indexes valid...
3862 int young_index = from_region->young_index_in_cset()+1;
3863 assert( (from_region->is_young() && young_index > 0) ||
3864 (!from_region->is_young() && young_index == 0), "invariant" );
3865 G1CollectorPolicy* g1p = _g1->g1_policy();
3866 markOop m = old->mark();
3867 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3868 : m->age();
3869 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3870 word_sz);
3871 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3872 oop obj = oop(obj_ptr);
3874 if (obj_ptr == NULL) {
3875 // This will either forward-to-self, or detect that someone else has
3876 // installed a forwarding pointer.
3877 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3878 return _g1->handle_evacuation_failure_par(cl, old);
3879 }
3881 // We're going to allocate linearly, so might as well prefetch ahead.
3882 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3884 oop forward_ptr = old->forward_to_atomic(obj);
3885 if (forward_ptr == NULL) {
3886 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3887 if (g1p->track_object_age(alloc_purpose)) {
3888 // We could simply do obj->incr_age(). However, this causes a
3889 // performance issue. obj->incr_age() will first check whether
3890 // the object has a displaced mark by checking its mark word;
3891 // getting the mark word from the new location of the object
3892 // stalls. So, given that we already have the mark word and we
3893 // are about to install it anyway, it's better to increase the
3894 // age on the mark word, when the object does not have a
3895 // displaced mark word. We're not expecting many objects to have
3896 // a displaced marked word, so that case is not optimized
3897 // further (it could be...) and we simply call obj->incr_age().
3899 if (m->has_displaced_mark_helper()) {
3900 // in this case, we have to install the mark word first,
3901 // otherwise obj looks to be forwarded (the old mark word,
3902 // which contains the forward pointer, was copied)
3903 obj->set_mark(m);
3904 obj->incr_age();
3905 } else {
3906 m = m->incr_age();
3907 obj->set_mark(m);
3908 }
3909 _par_scan_state->age_table()->add(obj, word_sz);
3910 } else {
3911 obj->set_mark(m);
3912 }
3914 // preserve "next" mark bit
3915 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3916 if (!use_local_bitmaps ||
3917 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3918 // if we couldn't mark it on the local bitmap (this happens when
3919 // the object was not allocated in the GCLab), we have to bite
3920 // the bullet and do the standard parallel mark
3921 _cm->markAndGrayObjectIfNecessary(obj);
3922 }
3923 #if 1
3924 if (_g1->isMarkedNext(old)) {
3925 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3926 }
3927 #endif
3928 }
3930 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3931 surv_young_words[young_index] += word_sz;
3933 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3934 arrayOop(old)->set_length(0);
3935 _par_scan_state->push_on_queue(set_partial_array_mask(old));
3936 } else {
3937 // No point in using the slower heap_region_containing() method,
3938 // given that we know obj is in the heap.
3939 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3940 obj->oop_iterate_backwards(_scanner);
3941 }
3942 } else {
3943 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3944 obj = forward_ptr;
3945 }
3946 return obj;
3947 }
3949 template<bool do_gen_barrier, G1Barrier barrier,
3950 bool do_mark_forwardee, bool skip_cset_test>
3951 void G1ParCopyClosure<do_gen_barrier, barrier,
3952 do_mark_forwardee, skip_cset_test>::do_oop_work(oop* p) {
3953 oop obj = *p;
3954 assert(barrier != G1BarrierRS || obj != NULL,
3955 "Precondition: G1BarrierRS implies obj is nonNull");
3957 // The only time we skip the cset test is when we're scanning
3958 // references popped from the queue. And we only push on the queue
3959 // references that we know point into the cset, so no point in
3960 // checking again. But we'll leave an assert here for peace of mind.
3961 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
3963 // here the null check is implicit in the cset_fast_test() test
3964 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
3965 #if G1_REM_SET_LOGGING
3966 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
3967 "into CS.", p, (void*) obj);
3968 #endif
3969 if (obj->is_forwarded()) {
3970 *p = obj->forwardee();
3971 } else {
3972 *p = copy_to_survivor_space(obj);
3973 }
3974 // When scanning the RS, we only care about objs in CS.
3975 if (barrier == G1BarrierRS) {
3976 _g1_rem->par_write_ref(_from, p, _par_scan_state->queue_num());
3977 }
3978 }
3980 // When scanning moved objs, must look at all oops.
3981 if (barrier == G1BarrierEvac && obj != NULL) {
3982 _g1_rem->par_write_ref(_from, p, _par_scan_state->queue_num());
3983 }
3985 if (do_gen_barrier && obj != NULL) {
3986 par_do_barrier(p);
3987 }
3988 }
3990 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
3992 template<class T> void G1ParScanPartialArrayClosure::process_array_chunk(
3993 oop obj, int start, int end) {
3994 // process our set of indices (include header in first chunk)
3995 assert(start < end, "invariant");
3996 T* const base = (T*)objArrayOop(obj)->base();
3997 T* const start_addr = (start == 0) ? (T*) obj : base + start;
3998 T* const end_addr = base + end;
3999 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
4000 _scanner.set_region(_g1->heap_region_containing(obj));
4001 obj->oop_iterate(&_scanner, mr);
4002 }
4004 void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) {
4005 assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops");
4006 assert(has_partial_array_mask(p), "invariant");
4007 oop old = clear_partial_array_mask(p);
4008 assert(old->is_objArray(), "must be obj array");
4009 assert(old->is_forwarded(), "must be forwarded");
4010 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4012 objArrayOop obj = objArrayOop(old->forwardee());
4013 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4014 // Process ParGCArrayScanChunk elements now
4015 // and push the remainder back onto queue
4016 int start = arrayOop(old)->length();
4017 int end = obj->length();
4018 int remainder = end - start;
4019 assert(start <= end, "just checking");
4020 if (remainder > 2 * ParGCArrayScanChunk) {
4021 // Test above combines last partial chunk with a full chunk
4022 end = start + ParGCArrayScanChunk;
4023 arrayOop(old)->set_length(end);
4024 // Push remainder.
4025 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4026 } else {
4027 // Restore length so that the heap remains parsable in
4028 // case of evacuation failure.
4029 arrayOop(old)->set_length(end);
4030 }
4032 // process our set of indices (include header in first chunk)
4033 process_array_chunk<oop>(obj, start, end);
4034 }
4036 int G1ScanAndBalanceClosure::_nq = 0;
4038 class G1ParEvacuateFollowersClosure : public VoidClosure {
4039 protected:
4040 G1CollectedHeap* _g1h;
4041 G1ParScanThreadState* _par_scan_state;
4042 RefToScanQueueSet* _queues;
4043 ParallelTaskTerminator* _terminator;
4045 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4046 RefToScanQueueSet* queues() { return _queues; }
4047 ParallelTaskTerminator* terminator() { return _terminator; }
4049 public:
4050 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4051 G1ParScanThreadState* par_scan_state,
4052 RefToScanQueueSet* queues,
4053 ParallelTaskTerminator* terminator)
4054 : _g1h(g1h), _par_scan_state(par_scan_state),
4055 _queues(queues), _terminator(terminator) {}
4057 void do_void() {
4058 G1ParScanThreadState* pss = par_scan_state();
4059 while (true) {
4060 oop* ref_to_scan;
4061 pss->trim_queue();
4062 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
4063 if (queues()->steal(pss->queue_num(),
4064 pss->hash_seed(),
4065 ref_to_scan)) {
4066 IF_G1_DETAILED_STATS(pss->note_steal());
4068 // slightly paranoid tests; I'm trying to catch potential
4069 // problems before we go into push_on_queue to know where the
4070 // problem is coming from
4071 assert(ref_to_scan != NULL, "invariant");
4072 assert(has_partial_array_mask(ref_to_scan) ||
4073 _g1h->obj_in_cs(*ref_to_scan), "invariant");
4074 pss->push_on_queue(ref_to_scan);
4075 continue;
4076 }
4077 pss->start_term_time();
4078 if (terminator()->offer_termination()) break;
4079 pss->end_term_time();
4080 }
4081 pss->end_term_time();
4082 pss->retire_alloc_buffers();
4083 }
4084 };
4086 class G1ParTask : public AbstractGangTask {
4087 protected:
4088 G1CollectedHeap* _g1h;
4089 RefToScanQueueSet *_queues;
4090 ParallelTaskTerminator _terminator;
4092 Mutex _stats_lock;
4093 Mutex* stats_lock() { return &_stats_lock; }
4095 size_t getNCards() {
4096 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4097 / G1BlockOffsetSharedArray::N_bytes;
4098 }
4100 public:
4101 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4102 : AbstractGangTask("G1 collection"),
4103 _g1h(g1h),
4104 _queues(task_queues),
4105 _terminator(workers, _queues),
4106 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4107 {}
4109 RefToScanQueueSet* queues() { return _queues; }
4111 RefToScanQueue *work_queue(int i) {
4112 return queues()->queue(i);
4113 }
4115 void work(int i) {
4116 ResourceMark rm;
4117 HandleMark hm;
4119 G1ParScanThreadState pss(_g1h, i);
4120 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4121 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4122 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4124 pss.set_evac_closure(&scan_evac_cl);
4125 pss.set_evac_failure_closure(&evac_failure_cl);
4126 pss.set_partial_scan_closure(&partial_scan_cl);
4128 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4129 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4130 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4131 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4132 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4133 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4135 OopsInHeapRegionClosure *scan_root_cl;
4136 OopsInHeapRegionClosure *scan_perm_cl;
4137 OopsInHeapRegionClosure *scan_so_cl;
4139 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
4140 scan_root_cl = &scan_mark_root_cl;
4141 scan_perm_cl = &scan_mark_perm_cl;
4142 scan_so_cl = &scan_mark_heap_rs_cl;
4143 } else {
4144 scan_root_cl = &only_scan_root_cl;
4145 scan_perm_cl = &only_scan_perm_cl;
4146 scan_so_cl = &only_scan_heap_rs_cl;
4147 }
4149 pss.start_strong_roots();
4150 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4151 SharedHeap::SO_AllClasses,
4152 scan_root_cl,
4153 &only_scan_heap_rs_cl,
4154 scan_so_cl,
4155 scan_perm_cl,
4156 i);
4157 pss.end_strong_roots();
4158 {
4159 double start = os::elapsedTime();
4160 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4161 evac.do_void();
4162 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4163 double term_ms = pss.term_time()*1000.0;
4164 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4165 _g1h->g1_policy()->record_termination_time(i, term_ms);
4166 }
4167 if (G1UseSurvivorSpace) {
4168 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4169 }
4170 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4172 // Clean up any par-expanded rem sets.
4173 HeapRegionRemSet::par_cleanup();
4175 MutexLocker x(stats_lock());
4176 if (ParallelGCVerbose) {
4177 gclog_or_tty->print("Thread %d complete:\n", i);
4178 #if G1_DETAILED_STATS
4179 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4180 pss.pushes(),
4181 pss.pops(),
4182 pss.overflow_pushes(),
4183 pss.steals(),
4184 pss.steal_attempts());
4185 #endif
4186 double elapsed = pss.elapsed();
4187 double strong_roots = pss.strong_roots_time();
4188 double term = pss.term_time();
4189 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4190 " Strong roots: %7.2f ms (%6.2f%%)\n"
4191 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4192 elapsed * 1000.0,
4193 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4194 term * 1000.0, (term*100.0/elapsed),
4195 pss.term_attempts());
4196 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4197 gclog_or_tty->print(" Waste: %8dK\n"
4198 " Alloc Buffer: %8dK\n"
4199 " Undo: %8dK\n",
4200 (total_waste * HeapWordSize) / K,
4201 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4202 (pss.undo_waste() * HeapWordSize) / K);
4203 }
4205 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4206 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4207 }
4208 };
4210 // *** Common G1 Evacuation Stuff
4212 class G1CountClosure: public OopsInHeapRegionClosure {
4213 public:
4214 int n;
4215 G1CountClosure() : n(0) {}
4216 void do_oop(narrowOop* p) {
4217 guarantee(false, "NYI");
4218 }
4219 void do_oop(oop* p) {
4220 oop obj = *p;
4221 assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj),
4222 "Rem set closure called on non-rem-set pointer.");
4223 n++;
4224 }
4225 };
4227 static G1CountClosure count_closure;
4229 void
4230 G1CollectedHeap::
4231 g1_process_strong_roots(bool collecting_perm_gen,
4232 SharedHeap::ScanningOption so,
4233 OopClosure* scan_non_heap_roots,
4234 OopsInHeapRegionClosure* scan_rs,
4235 OopsInHeapRegionClosure* scan_so,
4236 OopsInGenClosure* scan_perm,
4237 int worker_i) {
4238 // First scan the strong roots, including the perm gen.
4239 double ext_roots_start = os::elapsedTime();
4240 double closure_app_time_sec = 0.0;
4242 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4243 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4244 buf_scan_perm.set_generation(perm_gen());
4246 process_strong_roots(collecting_perm_gen, so,
4247 &buf_scan_non_heap_roots,
4248 &buf_scan_perm);
4249 // Finish up any enqueued closure apps.
4250 buf_scan_non_heap_roots.done();
4251 buf_scan_perm.done();
4252 double ext_roots_end = os::elapsedTime();
4253 g1_policy()->reset_obj_copy_time(worker_i);
4254 double obj_copy_time_sec =
4255 buf_scan_non_heap_roots.closure_app_seconds() +
4256 buf_scan_perm.closure_app_seconds();
4257 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4258 double ext_root_time_ms =
4259 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4260 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4262 // Scan strong roots in mark stack.
4263 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4264 concurrent_mark()->oops_do(scan_non_heap_roots);
4265 }
4266 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4267 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4269 // XXX What should this be doing in the parallel case?
4270 g1_policy()->record_collection_pause_end_CH_strong_roots();
4271 if (G1VerifyRemSet) {
4272 // :::: FIXME ::::
4273 // The stupid remembered set doesn't know how to filter out dead
4274 // objects, which the smart one does, and so when it is created
4275 // and then compared the number of entries in each differs and
4276 // the verification code fails.
4277 guarantee(false, "verification code is broken, see note");
4279 // Let's make sure that the current rem set agrees with the stupidest
4280 // one possible!
4281 bool refs_enabled = ref_processor()->discovery_enabled();
4282 if (refs_enabled) ref_processor()->disable_discovery();
4283 StupidG1RemSet stupid(this);
4284 count_closure.n = 0;
4285 stupid.oops_into_collection_set_do(&count_closure, worker_i);
4286 int stupid_n = count_closure.n;
4287 count_closure.n = 0;
4288 g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i);
4289 guarantee(count_closure.n == stupid_n, "Old and new rem sets differ.");
4290 gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n);
4291 if (refs_enabled) ref_processor()->enable_discovery();
4292 }
4293 if (scan_so != NULL) {
4294 scan_scan_only_set(scan_so, worker_i);
4295 }
4296 // Now scan the complement of the collection set.
4297 if (scan_rs != NULL) {
4298 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4299 }
4300 // Finish with the ref_processor roots.
4301 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4302 ref_processor()->oops_do(scan_non_heap_roots);
4303 }
4304 g1_policy()->record_collection_pause_end_G1_strong_roots();
4305 _process_strong_tasks->all_tasks_completed();
4306 }
4308 void
4309 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4310 OopsInHeapRegionClosure* oc,
4311 int worker_i) {
4312 HeapWord* startAddr = r->bottom();
4313 HeapWord* endAddr = r->used_region().end();
4315 oc->set_region(r);
4317 HeapWord* p = r->bottom();
4318 HeapWord* t = r->top();
4319 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4320 while (p < t) {
4321 oop obj = oop(p);
4322 p += obj->oop_iterate(oc);
4323 }
4324 }
4326 void
4327 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4328 int worker_i) {
4329 double start = os::elapsedTime();
4331 BufferingOopsInHeapRegionClosure boc(oc);
4333 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4334 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4336 OopsInHeapRegionClosure *foc;
4337 if (g1_policy()->should_initiate_conc_mark())
4338 foc = &scan_and_mark;
4339 else
4340 foc = &scan_only;
4342 HeapRegion* hr;
4343 int n = 0;
4344 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4345 scan_scan_only_region(hr, foc, worker_i);
4346 ++n;
4347 }
4348 boc.done();
4350 double closure_app_s = boc.closure_app_seconds();
4351 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4352 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4353 g1_policy()->record_scan_only_time(worker_i, ms, n);
4354 }
4356 void
4357 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4358 OopClosure* non_root_closure) {
4359 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4360 }
4363 class SaveMarksClosure: public HeapRegionClosure {
4364 public:
4365 bool doHeapRegion(HeapRegion* r) {
4366 r->save_marks();
4367 return false;
4368 }
4369 };
4371 void G1CollectedHeap::save_marks() {
4372 if (ParallelGCThreads == 0) {
4373 SaveMarksClosure sm;
4374 heap_region_iterate(&sm);
4375 }
4376 // We do this even in the parallel case
4377 perm_gen()->save_marks();
4378 }
4380 void G1CollectedHeap::evacuate_collection_set() {
4381 set_evacuation_failed(false);
4383 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4384 concurrent_g1_refine()->set_use_cache(false);
4385 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4387 set_par_threads(n_workers);
4388 G1ParTask g1_par_task(this, n_workers, _task_queues);
4390 init_for_evac_failure(NULL);
4392 change_strong_roots_parity(); // In preparation for parallel strong roots.
4393 rem_set()->prepare_for_younger_refs_iterate(true);
4394 double start_par = os::elapsedTime();
4396 if (ParallelGCThreads > 0) {
4397 // The individual threads will set their evac-failure closures.
4398 workers()->run_task(&g1_par_task);
4399 } else {
4400 g1_par_task.work(0);
4401 }
4403 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4404 g1_policy()->record_par_time(par_time);
4405 set_par_threads(0);
4406 // Is this the right thing to do here? We don't save marks
4407 // on individual heap regions when we allocate from
4408 // them in parallel, so this seems like the correct place for this.
4409 retire_all_alloc_regions();
4410 {
4411 G1IsAliveClosure is_alive(this);
4412 G1KeepAliveClosure keep_alive(this);
4413 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4414 }
4416 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4417 concurrent_g1_refine()->set_use_cache(true);
4419 finalize_for_evac_failure();
4421 // Must do this before removing self-forwarding pointers, which clears
4422 // the per-region evac-failure flags.
4423 concurrent_mark()->complete_marking_in_collection_set();
4425 if (evacuation_failed()) {
4426 remove_self_forwarding_pointers();
4428 if (PrintGCDetails) {
4429 gclog_or_tty->print(" (evacuation failed)");
4430 } else if (PrintGC) {
4431 gclog_or_tty->print("--");
4432 }
4433 }
4435 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4436 }
4438 void G1CollectedHeap::free_region(HeapRegion* hr) {
4439 size_t pre_used = 0;
4440 size_t cleared_h_regions = 0;
4441 size_t freed_regions = 0;
4442 UncleanRegionList local_list;
4444 HeapWord* start = hr->bottom();
4445 HeapWord* end = hr->prev_top_at_mark_start();
4446 size_t used_bytes = hr->used();
4447 size_t live_bytes = hr->max_live_bytes();
4448 if (used_bytes > 0) {
4449 guarantee( live_bytes <= used_bytes, "invariant" );
4450 } else {
4451 guarantee( live_bytes == 0, "invariant" );
4452 }
4454 size_t garbage_bytes = used_bytes - live_bytes;
4455 if (garbage_bytes > 0)
4456 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4458 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4459 &local_list);
4460 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4461 &local_list);
4462 }
4464 void
4465 G1CollectedHeap::free_region_work(HeapRegion* hr,
4466 size_t& pre_used,
4467 size_t& cleared_h_regions,
4468 size_t& freed_regions,
4469 UncleanRegionList* list,
4470 bool par) {
4471 assert(!hr->popular(), "should not free popular regions");
4472 pre_used += hr->used();
4473 if (hr->isHumongous()) {
4474 assert(hr->startsHumongous(),
4475 "Only the start of a humongous region should be freed.");
4476 int ind = _hrs->find(hr);
4477 assert(ind != -1, "Should have an index.");
4478 // Clear the start region.
4479 hr->hr_clear(par, true /*clear_space*/);
4480 list->insert_before_head(hr);
4481 cleared_h_regions++;
4482 freed_regions++;
4483 // Clear any continued regions.
4484 ind++;
4485 while ((size_t)ind < n_regions()) {
4486 HeapRegion* hrc = _hrs->at(ind);
4487 if (!hrc->continuesHumongous()) break;
4488 // Otherwise, does continue the H region.
4489 assert(hrc->humongous_start_region() == hr, "Huh?");
4490 hrc->hr_clear(par, true /*clear_space*/);
4491 cleared_h_regions++;
4492 freed_regions++;
4493 list->insert_before_head(hrc);
4494 ind++;
4495 }
4496 } else {
4497 hr->hr_clear(par, true /*clear_space*/);
4498 list->insert_before_head(hr);
4499 freed_regions++;
4500 // If we're using clear2, this should not be enabled.
4501 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4502 }
4503 }
4505 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4506 size_t cleared_h_regions,
4507 size_t freed_regions,
4508 UncleanRegionList* list) {
4509 if (list != NULL && list->sz() > 0) {
4510 prepend_region_list_on_unclean_list(list);
4511 }
4512 // Acquire a lock, if we're parallel, to update possibly-shared
4513 // variables.
4514 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4515 {
4516 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4517 _summary_bytes_used -= pre_used;
4518 _num_humongous_regions -= (int) cleared_h_regions;
4519 _free_regions += freed_regions;
4520 }
4521 }
4524 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4525 while (list != NULL) {
4526 guarantee( list->is_young(), "invariant" );
4528 HeapWord* bottom = list->bottom();
4529 HeapWord* end = list->end();
4530 MemRegion mr(bottom, end);
4531 ct_bs->dirty(mr);
4533 list = list->get_next_young_region();
4534 }
4535 }
4537 void G1CollectedHeap::cleanUpCardTable() {
4538 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4539 double start = os::elapsedTime();
4541 ct_bs->clear(_g1_committed);
4543 // now, redirty the cards of the scan-only and survivor regions
4544 // (it seemed faster to do it this way, instead of iterating over
4545 // all regions and then clearing / dirtying as approprite)
4546 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4547 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4549 double elapsed = os::elapsedTime() - start;
4550 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4551 }
4554 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4555 // First do any popular regions.
4556 HeapRegion* hr;
4557 while ((hr = popular_region_to_evac()) != NULL) {
4558 evac_popular_region(hr);
4559 }
4560 // Now do heuristic pauses.
4561 if (g1_policy()->should_do_collection_pause(word_size)) {
4562 do_collection_pause();
4563 }
4564 }
4566 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4567 double young_time_ms = 0.0;
4568 double non_young_time_ms = 0.0;
4570 G1CollectorPolicy* policy = g1_policy();
4572 double start_sec = os::elapsedTime();
4573 bool non_young = true;
4575 HeapRegion* cur = cs_head;
4576 int age_bound = -1;
4577 size_t rs_lengths = 0;
4579 while (cur != NULL) {
4580 if (non_young) {
4581 if (cur->is_young()) {
4582 double end_sec = os::elapsedTime();
4583 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4584 non_young_time_ms += elapsed_ms;
4586 start_sec = os::elapsedTime();
4587 non_young = false;
4588 }
4589 } else {
4590 if (!cur->is_on_free_list()) {
4591 double end_sec = os::elapsedTime();
4592 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4593 young_time_ms += elapsed_ms;
4595 start_sec = os::elapsedTime();
4596 non_young = true;
4597 }
4598 }
4600 rs_lengths += cur->rem_set()->occupied();
4602 HeapRegion* next = cur->next_in_collection_set();
4603 assert(cur->in_collection_set(), "bad CS");
4604 cur->set_next_in_collection_set(NULL);
4605 cur->set_in_collection_set(false);
4607 if (cur->is_young()) {
4608 int index = cur->young_index_in_cset();
4609 guarantee( index != -1, "invariant" );
4610 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4611 size_t words_survived = _surviving_young_words[index];
4612 cur->record_surv_words_in_group(words_survived);
4613 } else {
4614 int index = cur->young_index_in_cset();
4615 guarantee( index == -1, "invariant" );
4616 }
4618 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4619 (!cur->is_young() && cur->young_index_in_cset() == -1),
4620 "invariant" );
4622 if (!cur->evacuation_failed()) {
4623 // And the region is empty.
4624 assert(!cur->is_empty(),
4625 "Should not have empty regions in a CS.");
4626 free_region(cur);
4627 } else {
4628 guarantee( !cur->is_scan_only(), "should not be scan only" );
4629 cur->uninstall_surv_rate_group();
4630 if (cur->is_young())
4631 cur->set_young_index_in_cset(-1);
4632 cur->set_not_young();
4633 cur->set_evacuation_failed(false);
4634 }
4635 cur = next;
4636 }
4638 policy->record_max_rs_lengths(rs_lengths);
4639 policy->cset_regions_freed();
4641 double end_sec = os::elapsedTime();
4642 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4643 if (non_young)
4644 non_young_time_ms += elapsed_ms;
4645 else
4646 young_time_ms += elapsed_ms;
4648 policy->record_young_free_cset_time_ms(young_time_ms);
4649 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4650 }
4652 HeapRegion*
4653 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4654 assert(ZF_mon->owned_by_self(), "Precondition");
4655 HeapRegion* res = pop_unclean_region_list_locked();
4656 if (res != NULL) {
4657 assert(!res->continuesHumongous() &&
4658 res->zero_fill_state() != HeapRegion::Allocated,
4659 "Only free regions on unclean list.");
4660 if (zero_filled) {
4661 res->ensure_zero_filled_locked();
4662 res->set_zero_fill_allocated();
4663 }
4664 }
4665 return res;
4666 }
4668 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4669 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4670 return alloc_region_from_unclean_list_locked(zero_filled);
4671 }
4673 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4674 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4675 put_region_on_unclean_list_locked(r);
4676 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4677 }
4679 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4680 MutexLockerEx x(Cleanup_mon);
4681 set_unclean_regions_coming_locked(b);
4682 }
4684 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4685 assert(Cleanup_mon->owned_by_self(), "Precondition");
4686 _unclean_regions_coming = b;
4687 // Wake up mutator threads that might be waiting for completeCleanup to
4688 // finish.
4689 if (!b) Cleanup_mon->notify_all();
4690 }
4692 void G1CollectedHeap::wait_for_cleanup_complete() {
4693 MutexLockerEx x(Cleanup_mon);
4694 wait_for_cleanup_complete_locked();
4695 }
4697 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4698 assert(Cleanup_mon->owned_by_self(), "precondition");
4699 while (_unclean_regions_coming) {
4700 Cleanup_mon->wait();
4701 }
4702 }
4704 void
4705 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4706 assert(ZF_mon->owned_by_self(), "precondition.");
4707 _unclean_region_list.insert_before_head(r);
4708 }
4710 void
4711 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4712 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4713 prepend_region_list_on_unclean_list_locked(list);
4714 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4715 }
4717 void
4718 G1CollectedHeap::
4719 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4720 assert(ZF_mon->owned_by_self(), "precondition.");
4721 _unclean_region_list.prepend_list(list);
4722 }
4724 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4725 assert(ZF_mon->owned_by_self(), "precondition.");
4726 HeapRegion* res = _unclean_region_list.pop();
4727 if (res != NULL) {
4728 // Inform ZF thread that there's a new unclean head.
4729 if (_unclean_region_list.hd() != NULL && should_zf())
4730 ZF_mon->notify_all();
4731 }
4732 return res;
4733 }
4735 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4736 assert(ZF_mon->owned_by_self(), "precondition.");
4737 return _unclean_region_list.hd();
4738 }
4741 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4742 assert(ZF_mon->owned_by_self(), "Precondition");
4743 HeapRegion* r = peek_unclean_region_list_locked();
4744 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4745 // Result of below must be equal to "r", since we hold the lock.
4746 (void)pop_unclean_region_list_locked();
4747 put_free_region_on_list_locked(r);
4748 return true;
4749 } else {
4750 return false;
4751 }
4752 }
4754 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4755 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4756 return move_cleaned_region_to_free_list_locked();
4757 }
4760 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4761 assert(ZF_mon->owned_by_self(), "precondition.");
4762 assert(_free_region_list_size == free_region_list_length(), "Inv");
4763 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4764 "Regions on free list must be zero filled");
4765 assert(!r->isHumongous(), "Must not be humongous.");
4766 assert(r->is_empty(), "Better be empty");
4767 assert(!r->is_on_free_list(),
4768 "Better not already be on free list");
4769 assert(!r->is_on_unclean_list(),
4770 "Better not already be on unclean list");
4771 r->set_on_free_list(true);
4772 r->set_next_on_free_list(_free_region_list);
4773 _free_region_list = r;
4774 _free_region_list_size++;
4775 assert(_free_region_list_size == free_region_list_length(), "Inv");
4776 }
4778 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4779 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4780 put_free_region_on_list_locked(r);
4781 }
4783 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4784 assert(ZF_mon->owned_by_self(), "precondition.");
4785 assert(_free_region_list_size == free_region_list_length(), "Inv");
4786 HeapRegion* res = _free_region_list;
4787 if (res != NULL) {
4788 _free_region_list = res->next_from_free_list();
4789 _free_region_list_size--;
4790 res->set_on_free_list(false);
4791 res->set_next_on_free_list(NULL);
4792 assert(_free_region_list_size == free_region_list_length(), "Inv");
4793 }
4794 return res;
4795 }
4798 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4799 // By self, or on behalf of self.
4800 assert(Heap_lock->is_locked(), "Precondition");
4801 HeapRegion* res = NULL;
4802 bool first = true;
4803 while (res == NULL) {
4804 if (zero_filled || !first) {
4805 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4806 res = pop_free_region_list_locked();
4807 if (res != NULL) {
4808 assert(!res->zero_fill_is_allocated(),
4809 "No allocated regions on free list.");
4810 res->set_zero_fill_allocated();
4811 } else if (!first) {
4812 break; // We tried both, time to return NULL.
4813 }
4814 }
4816 if (res == NULL) {
4817 res = alloc_region_from_unclean_list(zero_filled);
4818 }
4819 assert(res == NULL ||
4820 !zero_filled ||
4821 res->zero_fill_is_allocated(),
4822 "We must have allocated the region we're returning");
4823 first = false;
4824 }
4825 return res;
4826 }
4828 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4829 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4830 {
4831 HeapRegion* prev = NULL;
4832 HeapRegion* cur = _unclean_region_list.hd();
4833 while (cur != NULL) {
4834 HeapRegion* next = cur->next_from_unclean_list();
4835 if (cur->zero_fill_is_allocated()) {
4836 // Remove from the list.
4837 if (prev == NULL) {
4838 (void)_unclean_region_list.pop();
4839 } else {
4840 _unclean_region_list.delete_after(prev);
4841 }
4842 cur->set_on_unclean_list(false);
4843 cur->set_next_on_unclean_list(NULL);
4844 } else {
4845 prev = cur;
4846 }
4847 cur = next;
4848 }
4849 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4850 "Inv");
4851 }
4853 {
4854 HeapRegion* prev = NULL;
4855 HeapRegion* cur = _free_region_list;
4856 while (cur != NULL) {
4857 HeapRegion* next = cur->next_from_free_list();
4858 if (cur->zero_fill_is_allocated()) {
4859 // Remove from the list.
4860 if (prev == NULL) {
4861 _free_region_list = cur->next_from_free_list();
4862 } else {
4863 prev->set_next_on_free_list(cur->next_from_free_list());
4864 }
4865 cur->set_on_free_list(false);
4866 cur->set_next_on_free_list(NULL);
4867 _free_region_list_size--;
4868 } else {
4869 prev = cur;
4870 }
4871 cur = next;
4872 }
4873 assert(_free_region_list_size == free_region_list_length(), "Inv");
4874 }
4875 }
4877 bool G1CollectedHeap::verify_region_lists() {
4878 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4879 return verify_region_lists_locked();
4880 }
4882 bool G1CollectedHeap::verify_region_lists_locked() {
4883 HeapRegion* unclean = _unclean_region_list.hd();
4884 while (unclean != NULL) {
4885 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4886 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4887 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4888 "Everything else is possible.");
4889 unclean = unclean->next_from_unclean_list();
4890 }
4891 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4893 HeapRegion* free_r = _free_region_list;
4894 while (free_r != NULL) {
4895 assert(free_r->is_on_free_list(), "Well, it is!");
4896 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4897 switch (free_r->zero_fill_state()) {
4898 case HeapRegion::NotZeroFilled:
4899 case HeapRegion::ZeroFilling:
4900 guarantee(false, "Should not be on free list.");
4901 break;
4902 default:
4903 // Everything else is possible.
4904 break;
4905 }
4906 free_r = free_r->next_from_free_list();
4907 }
4908 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4909 // If we didn't do an assertion...
4910 return true;
4911 }
4913 size_t G1CollectedHeap::free_region_list_length() {
4914 assert(ZF_mon->owned_by_self(), "precondition.");
4915 size_t len = 0;
4916 HeapRegion* cur = _free_region_list;
4917 while (cur != NULL) {
4918 len++;
4919 cur = cur->next_from_free_list();
4920 }
4921 return len;
4922 }
4924 size_t G1CollectedHeap::unclean_region_list_length() {
4925 assert(ZF_mon->owned_by_self(), "precondition.");
4926 return _unclean_region_list.length();
4927 }
4929 size_t G1CollectedHeap::n_regions() {
4930 return _hrs->length();
4931 }
4933 size_t G1CollectedHeap::max_regions() {
4934 return
4935 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4936 HeapRegion::GrainBytes;
4937 }
4939 size_t G1CollectedHeap::free_regions() {
4940 /* Possibly-expensive assert.
4941 assert(_free_regions == count_free_regions(),
4942 "_free_regions is off.");
4943 */
4944 return _free_regions;
4945 }
4947 bool G1CollectedHeap::should_zf() {
4948 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4949 }
4951 class RegionCounter: public HeapRegionClosure {
4952 size_t _n;
4953 public:
4954 RegionCounter() : _n(0) {}
4955 bool doHeapRegion(HeapRegion* r) {
4956 if (r->is_empty() && !r->popular()) {
4957 assert(!r->isHumongous(), "H regions should not be empty.");
4958 _n++;
4959 }
4960 return false;
4961 }
4962 int res() { return (int) _n; }
4963 };
4965 size_t G1CollectedHeap::count_free_regions() {
4966 RegionCounter rc;
4967 heap_region_iterate(&rc);
4968 size_t n = rc.res();
4969 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4970 n--;
4971 return n;
4972 }
4974 size_t G1CollectedHeap::count_free_regions_list() {
4975 size_t n = 0;
4976 size_t o = 0;
4977 ZF_mon->lock_without_safepoint_check();
4978 HeapRegion* cur = _free_region_list;
4979 while (cur != NULL) {
4980 cur = cur->next_from_free_list();
4981 n++;
4982 }
4983 size_t m = unclean_region_list_length();
4984 ZF_mon->unlock();
4985 return n + m;
4986 }
4988 bool G1CollectedHeap::should_set_young_locked() {
4989 assert(heap_lock_held_for_gc(),
4990 "the heap lock should already be held by or for this thread");
4991 return (g1_policy()->in_young_gc_mode() &&
4992 g1_policy()->should_add_next_region_to_young_list());
4993 }
4995 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4996 assert(heap_lock_held_for_gc(),
4997 "the heap lock should already be held by or for this thread");
4998 _young_list->push_region(hr);
4999 g1_policy()->set_region_short_lived(hr);
5000 }
5002 class NoYoungRegionsClosure: public HeapRegionClosure {
5003 private:
5004 bool _success;
5005 public:
5006 NoYoungRegionsClosure() : _success(true) { }
5007 bool doHeapRegion(HeapRegion* r) {
5008 if (r->is_young()) {
5009 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5010 r->bottom(), r->end());
5011 _success = false;
5012 }
5013 return false;
5014 }
5015 bool success() { return _success; }
5016 };
5018 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
5019 bool check_sample) {
5020 bool ret = true;
5022 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
5023 if (!ignore_scan_only_list) {
5024 NoYoungRegionsClosure closure;
5025 heap_region_iterate(&closure);
5026 ret = ret && closure.success();
5027 }
5029 return ret;
5030 }
5032 void G1CollectedHeap::empty_young_list() {
5033 assert(heap_lock_held_for_gc(),
5034 "the heap lock should already be held by or for this thread");
5035 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5037 _young_list->empty_list();
5038 }
5040 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5041 bool no_allocs = true;
5042 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5043 HeapRegion* r = _gc_alloc_regions[ap];
5044 no_allocs = r == NULL || r->saved_mark_at_top();
5045 }
5046 return no_allocs;
5047 }
5049 void G1CollectedHeap::retire_all_alloc_regions() {
5050 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5051 HeapRegion* r = _gc_alloc_regions[ap];
5052 if (r != NULL) {
5053 // Check for aliases.
5054 bool has_processed_alias = false;
5055 for (int i = 0; i < ap; ++i) {
5056 if (_gc_alloc_regions[i] == r) {
5057 has_processed_alias = true;
5058 break;
5059 }
5060 }
5061 if (!has_processed_alias) {
5062 retire_alloc_region(r, false /* par */);
5063 }
5064 }
5065 }
5066 }
5069 // Done at the start of full GC.
5070 void G1CollectedHeap::tear_down_region_lists() {
5071 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5072 while (pop_unclean_region_list_locked() != NULL) ;
5073 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5074 "Postconditions of loop.")
5075 while (pop_free_region_list_locked() != NULL) ;
5076 assert(_free_region_list == NULL, "Postcondition of loop.");
5077 if (_free_region_list_size != 0) {
5078 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5079 print();
5080 }
5081 assert(_free_region_list_size == 0, "Postconditions of loop.");
5082 }
5085 class RegionResetter: public HeapRegionClosure {
5086 G1CollectedHeap* _g1;
5087 int _n;
5088 public:
5089 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5090 bool doHeapRegion(HeapRegion* r) {
5091 if (r->continuesHumongous()) return false;
5092 if (r->top() > r->bottom()) {
5093 if (r->top() < r->end()) {
5094 Copy::fill_to_words(r->top(),
5095 pointer_delta(r->end(), r->top()));
5096 }
5097 r->set_zero_fill_allocated();
5098 } else {
5099 assert(r->is_empty(), "tautology");
5100 if (r->popular()) {
5101 if (r->zero_fill_state() != HeapRegion::Allocated) {
5102 r->ensure_zero_filled_locked();
5103 r->set_zero_fill_allocated();
5104 }
5105 } else {
5106 _n++;
5107 switch (r->zero_fill_state()) {
5108 case HeapRegion::NotZeroFilled:
5109 case HeapRegion::ZeroFilling:
5110 _g1->put_region_on_unclean_list_locked(r);
5111 break;
5112 case HeapRegion::Allocated:
5113 r->set_zero_fill_complete();
5114 // no break; go on to put on free list.
5115 case HeapRegion::ZeroFilled:
5116 _g1->put_free_region_on_list_locked(r);
5117 break;
5118 }
5119 }
5120 }
5121 return false;
5122 }
5124 int getFreeRegionCount() {return _n;}
5125 };
5127 // Done at the end of full GC.
5128 void G1CollectedHeap::rebuild_region_lists() {
5129 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5130 // This needs to go at the end of the full GC.
5131 RegionResetter rs;
5132 heap_region_iterate(&rs);
5133 _free_regions = rs.getFreeRegionCount();
5134 // Tell the ZF thread it may have work to do.
5135 if (should_zf()) ZF_mon->notify_all();
5136 }
5138 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5139 G1CollectedHeap* _g1;
5140 int _n;
5141 public:
5142 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5143 bool doHeapRegion(HeapRegion* r) {
5144 if (r->continuesHumongous()) return false;
5145 if (r->top() > r->bottom()) {
5146 // There are assertions in "set_zero_fill_needed()" below that
5147 // require top() == bottom(), so this is technically illegal.
5148 // We'll skirt the law here, by making that true temporarily.
5149 DEBUG_ONLY(HeapWord* save_top = r->top();
5150 r->set_top(r->bottom()));
5151 r->set_zero_fill_needed();
5152 DEBUG_ONLY(r->set_top(save_top));
5153 }
5154 return false;
5155 }
5156 };
5158 // Done at the start of full GC.
5159 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5160 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5161 // This needs to go at the end of the full GC.
5162 UsedRegionsNeedZeroFillSetter rs;
5163 heap_region_iterate(&rs);
5164 }
5166 class CountObjClosure: public ObjectClosure {
5167 size_t _n;
5168 public:
5169 CountObjClosure() : _n(0) {}
5170 void do_object(oop obj) { _n++; }
5171 size_t n() { return _n; }
5172 };
5174 size_t G1CollectedHeap::pop_object_used_objs() {
5175 size_t sum_objs = 0;
5176 for (int i = 0; i < G1NumPopularRegions; i++) {
5177 CountObjClosure cl;
5178 _hrs->at(i)->object_iterate(&cl);
5179 sum_objs += cl.n();
5180 }
5181 return sum_objs;
5182 }
5184 size_t G1CollectedHeap::pop_object_used_bytes() {
5185 size_t sum_bytes = 0;
5186 for (int i = 0; i < G1NumPopularRegions; i++) {
5187 sum_bytes += _hrs->at(i)->used();
5188 }
5189 return sum_bytes;
5190 }
5193 static int nq = 0;
5195 HeapWord* G1CollectedHeap::allocate_popular_object(size_t word_size) {
5196 while (_cur_pop_hr_index < G1NumPopularRegions) {
5197 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5198 HeapWord* res = cur_pop_region->allocate(word_size);
5199 if (res != NULL) {
5200 // We account for popular objs directly in the used summary:
5201 _summary_bytes_used += (word_size * HeapWordSize);
5202 return res;
5203 }
5204 // Otherwise, try the next region (first making sure that we remember
5205 // the last "top" value as the "next_top_at_mark_start", so that
5206 // objects made popular during markings aren't automatically considered
5207 // live).
5208 cur_pop_region->note_end_of_copying();
5209 // Otherwise, try the next region.
5210 _cur_pop_hr_index++;
5211 }
5212 // XXX: For now !!!
5213 vm_exit_out_of_memory(word_size,
5214 "Not enough pop obj space (To Be Fixed)");
5215 return NULL;
5216 }
5218 class HeapRegionList: public CHeapObj {
5219 public:
5220 HeapRegion* hr;
5221 HeapRegionList* next;
5222 };
5224 void G1CollectedHeap::schedule_popular_region_evac(HeapRegion* r) {
5225 // This might happen during parallel GC, so protect by this lock.
5226 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5227 // We don't schedule regions whose evacuations are already pending, or
5228 // are already being evacuated.
5229 if (!r->popular_pending() && !r->in_collection_set()) {
5230 r->set_popular_pending(true);
5231 if (G1TracePopularity) {
5232 gclog_or_tty->print_cr("Scheduling region "PTR_FORMAT" "
5233 "["PTR_FORMAT", "PTR_FORMAT") for pop-object evacuation.",
5234 r, r->bottom(), r->end());
5235 }
5236 HeapRegionList* hrl = new HeapRegionList;
5237 hrl->hr = r;
5238 hrl->next = _popular_regions_to_be_evacuated;
5239 _popular_regions_to_be_evacuated = hrl;
5240 }
5241 }
5243 HeapRegion* G1CollectedHeap::popular_region_to_evac() {
5244 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5245 HeapRegion* res = NULL;
5246 while (_popular_regions_to_be_evacuated != NULL && res == NULL) {
5247 HeapRegionList* hrl = _popular_regions_to_be_evacuated;
5248 _popular_regions_to_be_evacuated = hrl->next;
5249 res = hrl->hr;
5250 // The G1RSPopLimit may have increased, so recheck here...
5251 if (res->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5252 // Hah: don't need to schedule.
5253 if (G1TracePopularity) {
5254 gclog_or_tty->print_cr("Unscheduling region "PTR_FORMAT" "
5255 "["PTR_FORMAT", "PTR_FORMAT") "
5256 "for pop-object evacuation (size %d < limit %d)",
5257 res, res->bottom(), res->end(),
5258 res->rem_set()->occupied(), G1RSPopLimit);
5259 }
5260 res->set_popular_pending(false);
5261 res = NULL;
5262 }
5263 // We do not reset res->popular() here; if we did so, it would allow
5264 // the region to be "rescheduled" for popularity evacuation. Instead,
5265 // this is done in the collection pause, with the world stopped.
5266 // So the invariant is that the regions in the list have the popularity
5267 // boolean set, but having the boolean set does not imply membership
5268 // on the list (though there can at most one such pop-pending region
5269 // not on the list at any time).
5270 delete hrl;
5271 }
5272 return res;
5273 }
5275 void G1CollectedHeap::evac_popular_region(HeapRegion* hr) {
5276 while (true) {
5277 // Don't want to do a GC pause while cleanup is being completed!
5278 wait_for_cleanup_complete();
5280 // Read the GC count while holding the Heap_lock
5281 int gc_count_before = SharedHeap::heap()->total_collections();
5282 g1_policy()->record_stop_world_start();
5284 {
5285 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
5286 VM_G1PopRegionCollectionPause op(gc_count_before, hr);
5287 VMThread::execute(&op);
5289 // If the prolog succeeded, we didn't do a GC for this.
5290 if (op.prologue_succeeded()) break;
5291 }
5292 // Otherwise we didn't. We should recheck the size, though, since
5293 // the limit may have increased...
5294 if (hr->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5295 hr->set_popular_pending(false);
5296 break;
5297 }
5298 }
5299 }
5301 void G1CollectedHeap::atomic_inc_obj_rc(oop obj) {
5302 Atomic::inc(obj_rc_addr(obj));
5303 }
5305 class CountRCClosure: public OopsInHeapRegionClosure {
5306 G1CollectedHeap* _g1h;
5307 bool _parallel;
5308 public:
5309 CountRCClosure(G1CollectedHeap* g1h) :
5310 _g1h(g1h), _parallel(ParallelGCThreads > 0)
5311 {}
5312 void do_oop(narrowOop* p) {
5313 guarantee(false, "NYI");
5314 }
5315 void do_oop(oop* p) {
5316 oop obj = *p;
5317 assert(obj != NULL, "Precondition.");
5318 if (_parallel) {
5319 // We go sticky at the limit to avoid excess contention.
5320 // If we want to track the actual RC's further, we'll need to keep a
5321 // per-thread hash table or something for the popular objects.
5322 if (_g1h->obj_rc(obj) < G1ObjPopLimit) {
5323 _g1h->atomic_inc_obj_rc(obj);
5324 }
5325 } else {
5326 _g1h->inc_obj_rc(obj);
5327 }
5328 }
5329 };
5331 class EvacPopObjClosure: public ObjectClosure {
5332 G1CollectedHeap* _g1h;
5333 size_t _pop_objs;
5334 size_t _max_rc;
5335 public:
5336 EvacPopObjClosure(G1CollectedHeap* g1h) :
5337 _g1h(g1h), _pop_objs(0), _max_rc(0) {}
5339 void do_object(oop obj) {
5340 size_t rc = _g1h->obj_rc(obj);
5341 _max_rc = MAX2(rc, _max_rc);
5342 if (rc >= (size_t) G1ObjPopLimit) {
5343 _g1h->_pop_obj_rc_at_copy.add((double)rc);
5344 size_t word_sz = obj->size();
5345 HeapWord* new_pop_loc = _g1h->allocate_popular_object(word_sz);
5346 oop new_pop_obj = (oop)new_pop_loc;
5347 Copy::aligned_disjoint_words((HeapWord*)obj, new_pop_loc, word_sz);
5348 obj->forward_to(new_pop_obj);
5349 G1ScanAndBalanceClosure scan_and_balance(_g1h);
5350 new_pop_obj->oop_iterate_backwards(&scan_and_balance);
5351 // preserve "next" mark bit if marking is in progress.
5352 if (_g1h->mark_in_progress() && !_g1h->is_obj_ill(obj)) {
5353 _g1h->concurrent_mark()->markAndGrayObjectIfNecessary(new_pop_obj);
5354 }
5356 if (G1TracePopularity) {
5357 gclog_or_tty->print_cr("Found obj " PTR_FORMAT " of word size " SIZE_FORMAT
5358 " pop (%d), move to " PTR_FORMAT,
5359 (void*) obj, word_sz,
5360 _g1h->obj_rc(obj), (void*) new_pop_obj);
5361 }
5362 _pop_objs++;
5363 }
5364 }
5365 size_t pop_objs() { return _pop_objs; }
5366 size_t max_rc() { return _max_rc; }
5367 };
5369 class G1ParCountRCTask : public AbstractGangTask {
5370 G1CollectedHeap* _g1h;
5371 BitMap _bm;
5373 size_t getNCards() {
5374 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5375 / G1BlockOffsetSharedArray::N_bytes;
5376 }
5377 CountRCClosure _count_rc_closure;
5378 public:
5379 G1ParCountRCTask(G1CollectedHeap* g1h) :
5380 AbstractGangTask("G1 Par RC Count task"),
5381 _g1h(g1h), _bm(getNCards()), _count_rc_closure(g1h)
5382 {}
5384 void work(int i) {
5385 ResourceMark rm;
5386 HandleMark hm;
5387 _g1h->g1_rem_set()->oops_into_collection_set_do(&_count_rc_closure, i);
5388 }
5389 };
5391 void G1CollectedHeap::popularity_pause_preamble(HeapRegion* popular_region) {
5392 // We're evacuating a single region (for popularity).
5393 if (G1TracePopularity) {
5394 gclog_or_tty->print_cr("Doing pop region pause for ["PTR_FORMAT", "PTR_FORMAT")",
5395 popular_region->bottom(), popular_region->end());
5396 }
5397 g1_policy()->set_single_region_collection_set(popular_region);
5398 size_t max_rc;
5399 if (!compute_reference_counts_and_evac_popular(popular_region,
5400 &max_rc)) {
5401 // We didn't evacuate any popular objects.
5402 // We increase the RS popularity limit, to prevent this from
5403 // happening in the future.
5404 if (G1RSPopLimit < (1 << 30)) {
5405 G1RSPopLimit *= 2;
5406 }
5407 // For now, interesting enough for a message:
5408 #if 1
5409 gclog_or_tty->print_cr("In pop region pause for ["PTR_FORMAT", "PTR_FORMAT"), "
5410 "failed to find a pop object (max = %d).",
5411 popular_region->bottom(), popular_region->end(),
5412 max_rc);
5413 gclog_or_tty->print_cr("Increased G1RSPopLimit to %d.", G1RSPopLimit);
5414 #endif // 0
5415 // Also, we reset the collection set to NULL, to make the rest of
5416 // the collection do nothing.
5417 assert(popular_region->next_in_collection_set() == NULL,
5418 "should be single-region.");
5419 popular_region->set_in_collection_set(false);
5420 popular_region->set_popular_pending(false);
5421 g1_policy()->clear_collection_set();
5422 }
5423 }
5425 bool G1CollectedHeap::
5426 compute_reference_counts_and_evac_popular(HeapRegion* popular_region,
5427 size_t* max_rc) {
5428 HeapWord* rc_region_bot;
5429 HeapWord* rc_region_end;
5431 // Set up the reference count region.
5432 HeapRegion* rc_region = newAllocRegion(HeapRegion::GrainWords);
5433 if (rc_region != NULL) {
5434 rc_region_bot = rc_region->bottom();
5435 rc_region_end = rc_region->end();
5436 } else {
5437 rc_region_bot = NEW_C_HEAP_ARRAY(HeapWord, HeapRegion::GrainWords);
5438 if (rc_region_bot == NULL) {
5439 vm_exit_out_of_memory(HeapRegion::GrainWords,
5440 "No space for RC region.");
5441 }
5442 rc_region_end = rc_region_bot + HeapRegion::GrainWords;
5443 }
5445 if (G1TracePopularity)
5446 gclog_or_tty->print_cr("RC region is ["PTR_FORMAT", "PTR_FORMAT")",
5447 rc_region_bot, rc_region_end);
5448 if (rc_region_bot > popular_region->bottom()) {
5449 _rc_region_above = true;
5450 _rc_region_diff =
5451 pointer_delta(rc_region_bot, popular_region->bottom(), 1);
5452 } else {
5453 assert(rc_region_bot < popular_region->bottom(), "Can't be equal.");
5454 _rc_region_above = false;
5455 _rc_region_diff =
5456 pointer_delta(popular_region->bottom(), rc_region_bot, 1);
5457 }
5458 g1_policy()->record_pop_compute_rc_start();
5459 // Count external references.
5460 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5461 if (ParallelGCThreads > 0) {
5463 set_par_threads(workers()->total_workers());
5464 G1ParCountRCTask par_count_rc_task(this);
5465 workers()->run_task(&par_count_rc_task);
5466 set_par_threads(0);
5468 } else {
5469 CountRCClosure count_rc_closure(this);
5470 g1_rem_set()->oops_into_collection_set_do(&count_rc_closure, 0);
5471 }
5472 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5473 g1_policy()->record_pop_compute_rc_end();
5475 // Now evacuate popular objects.
5476 g1_policy()->record_pop_evac_start();
5477 EvacPopObjClosure evac_pop_obj_cl(this);
5478 popular_region->object_iterate(&evac_pop_obj_cl);
5479 *max_rc = evac_pop_obj_cl.max_rc();
5481 // Make sure the last "top" value of the current popular region is copied
5482 // as the "next_top_at_mark_start", so that objects made popular during
5483 // markings aren't automatically considered live.
5484 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5485 cur_pop_region->note_end_of_copying();
5487 if (rc_region != NULL) {
5488 free_region(rc_region);
5489 } else {
5490 FREE_C_HEAP_ARRAY(HeapWord, rc_region_bot);
5491 }
5492 g1_policy()->record_pop_evac_end();
5494 return evac_pop_obj_cl.pop_objs() > 0;
5495 }
5497 class CountPopObjInfoClosure: public HeapRegionClosure {
5498 size_t _objs;
5499 size_t _bytes;
5501 class CountObjClosure: public ObjectClosure {
5502 int _n;
5503 public:
5504 CountObjClosure() : _n(0) {}
5505 void do_object(oop obj) { _n++; }
5506 size_t n() { return _n; }
5507 };
5509 public:
5510 CountPopObjInfoClosure() : _objs(0), _bytes(0) {}
5511 bool doHeapRegion(HeapRegion* r) {
5512 _bytes += r->used();
5513 CountObjClosure blk;
5514 r->object_iterate(&blk);
5515 _objs += blk.n();
5516 return false;
5517 }
5518 size_t objs() { return _objs; }
5519 size_t bytes() { return _bytes; }
5520 };
5523 void G1CollectedHeap::print_popularity_summary_info() const {
5524 CountPopObjInfoClosure blk;
5525 for (int i = 0; i <= _cur_pop_hr_index; i++) {
5526 blk.doHeapRegion(_hrs->at(i));
5527 }
5528 gclog_or_tty->print_cr("\nPopular objects: %d objs, %d bytes.",
5529 blk.objs(), blk.bytes());
5530 gclog_or_tty->print_cr(" RC at copy = [avg = %5.2f, max = %5.2f, sd = %5.2f].",
5531 _pop_obj_rc_at_copy.avg(),
5532 _pop_obj_rc_at_copy.maximum(),
5533 _pop_obj_rc_at_copy.sd());
5534 }
5536 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5537 _refine_cte_cl->set_concurrent(concurrent);
5538 }
5540 #ifndef PRODUCT
5542 class PrintHeapRegionClosure: public HeapRegionClosure {
5543 public:
5544 bool doHeapRegion(HeapRegion *r) {
5545 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5546 if (r != NULL) {
5547 if (r->is_on_free_list())
5548 gclog_or_tty->print("Free ");
5549 if (r->is_young())
5550 gclog_or_tty->print("Young ");
5551 if (r->isHumongous())
5552 gclog_or_tty->print("Is Humongous ");
5553 r->print();
5554 }
5555 return false;
5556 }
5557 };
5559 class SortHeapRegionClosure : public HeapRegionClosure {
5560 size_t young_regions,free_regions, unclean_regions;
5561 size_t hum_regions, count;
5562 size_t unaccounted, cur_unclean, cur_alloc;
5563 size_t total_free;
5564 HeapRegion* cur;
5565 public:
5566 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5567 free_regions(0), unclean_regions(0),
5568 hum_regions(0),
5569 count(0), unaccounted(0),
5570 cur_alloc(0), total_free(0)
5571 {}
5572 bool doHeapRegion(HeapRegion *r) {
5573 count++;
5574 if (r->is_on_free_list()) free_regions++;
5575 else if (r->is_on_unclean_list()) unclean_regions++;
5576 else if (r->isHumongous()) hum_regions++;
5577 else if (r->is_young()) young_regions++;
5578 else if (r == cur) cur_alloc++;
5579 else unaccounted++;
5580 return false;
5581 }
5582 void print() {
5583 total_free = free_regions + unclean_regions;
5584 gclog_or_tty->print("%d regions\n", count);
5585 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5586 total_free, free_regions, unclean_regions);
5587 gclog_or_tty->print("%d humongous %d young\n",
5588 hum_regions, young_regions);
5589 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5590 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5591 }
5592 };
5594 void G1CollectedHeap::print_region_counts() {
5595 SortHeapRegionClosure sc(_cur_alloc_region);
5596 PrintHeapRegionClosure cl;
5597 heap_region_iterate(&cl);
5598 heap_region_iterate(&sc);
5599 sc.print();
5600 print_region_accounting_info();
5601 };
5603 bool G1CollectedHeap::regions_accounted_for() {
5604 // TODO: regions accounting for young/survivor/tenured
5605 return true;
5606 }
5608 bool G1CollectedHeap::print_region_accounting_info() {
5609 gclog_or_tty->print_cr("P regions: %d.", G1NumPopularRegions);
5610 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5611 free_regions(),
5612 count_free_regions(), count_free_regions_list(),
5613 _free_region_list_size, _unclean_region_list.sz());
5614 gclog_or_tty->print_cr("cur_alloc: %d.",
5615 (_cur_alloc_region == NULL ? 0 : 1));
5616 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5618 // TODO: check regions accounting for young/survivor/tenured
5619 return true;
5620 }
5622 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5623 HeapRegion* hr = heap_region_containing(p);
5624 if (hr == NULL) {
5625 return is_in_permanent(p);
5626 } else {
5627 return hr->is_in(p);
5628 }
5629 }
5630 #endif // PRODUCT
5632 void G1CollectedHeap::g1_unimplemented() {
5633 // Unimplemented();
5634 }
5637 // Local Variables: ***
5638 // c-indentation-style: gnu ***
5639 // End: ***