Mon, 31 Aug 2009 05:27:29 -0700
6841313: G1: dirty cards of survivor regions in parallel
Reviewed-by: tonyp, iveresov
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectedHeap.cpp.incl"
28 // turn it on so that the contents of the young list (scan-only /
29 // to-be-collected) are printed at "strategic" points before / during
30 // / after the collection --- this is useful for debugging
31 #define SCAN_ONLY_VERBOSE 0
32 // CURRENT STATUS
33 // This file is under construction. Search for "FIXME".
35 // INVARIANTS/NOTES
36 //
37 // All allocation activity covered by the G1CollectedHeap interface is
38 // serialized by acquiring the HeapLock. This happens in
39 // mem_allocate_work, which all such allocation functions call.
40 // (Note that this does not apply to TLAB allocation, which is not part
41 // of this interface: it is done by clients of this interface.)
43 // Local to this file.
45 class RefineCardTableEntryClosure: public CardTableEntryClosure {
46 SuspendibleThreadSet* _sts;
47 G1RemSet* _g1rs;
48 ConcurrentG1Refine* _cg1r;
49 bool _concurrent;
50 public:
51 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
52 G1RemSet* g1rs,
53 ConcurrentG1Refine* cg1r) :
54 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
55 {}
56 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
57 _g1rs->concurrentRefineOneCard(card_ptr, worker_i);
58 if (_concurrent && _sts->should_yield()) {
59 // Caller will actually yield.
60 return false;
61 }
62 // Otherwise, we finished successfully; return true.
63 return true;
64 }
65 void set_concurrent(bool b) { _concurrent = b; }
66 };
69 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
70 int _calls;
71 G1CollectedHeap* _g1h;
72 CardTableModRefBS* _ctbs;
73 int _histo[256];
74 public:
75 ClearLoggedCardTableEntryClosure() :
76 _calls(0)
77 {
78 _g1h = G1CollectedHeap::heap();
79 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
80 for (int i = 0; i < 256; i++) _histo[i] = 0;
81 }
82 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
83 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
84 _calls++;
85 unsigned char* ujb = (unsigned char*)card_ptr;
86 int ind = (int)(*ujb);
87 _histo[ind]++;
88 *card_ptr = -1;
89 }
90 return true;
91 }
92 int calls() { return _calls; }
93 void print_histo() {
94 gclog_or_tty->print_cr("Card table value histogram:");
95 for (int i = 0; i < 256; i++) {
96 if (_histo[i] != 0) {
97 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
98 }
99 }
100 }
101 };
103 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
104 int _calls;
105 G1CollectedHeap* _g1h;
106 CardTableModRefBS* _ctbs;
107 public:
108 RedirtyLoggedCardTableEntryClosure() :
109 _calls(0)
110 {
111 _g1h = G1CollectedHeap::heap();
112 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
113 }
114 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
115 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
116 _calls++;
117 *card_ptr = 0;
118 }
119 return true;
120 }
121 int calls() { return _calls; }
122 };
124 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
125 public:
126 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 return true;
129 }
130 };
132 YoungList::YoungList(G1CollectedHeap* g1h)
133 : _g1h(g1h), _head(NULL),
134 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
135 _length(0), _scan_only_length(0),
136 _last_sampled_rs_lengths(0),
137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
138 {
139 guarantee( check_list_empty(false), "just making sure..." );
140 }
142 void YoungList::push_region(HeapRegion *hr) {
143 assert(!hr->is_young(), "should not already be young");
144 assert(hr->get_next_young_region() == NULL, "cause it should!");
146 hr->set_next_young_region(_head);
147 _head = hr;
149 hr->set_young();
150 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
151 ++_length;
152 }
154 void YoungList::add_survivor_region(HeapRegion* hr) {
155 assert(hr->is_survivor(), "should be flagged as survivor region");
156 assert(hr->get_next_young_region() == NULL, "cause it should!");
158 hr->set_next_young_region(_survivor_head);
159 if (_survivor_head == NULL) {
160 _survivor_tail = hr;
161 }
162 _survivor_head = hr;
164 ++_survivor_length;
165 }
167 HeapRegion* YoungList::pop_region() {
168 while (_head != NULL) {
169 assert( length() > 0, "list should not be empty" );
170 HeapRegion* ret = _head;
171 _head = ret->get_next_young_region();
172 ret->set_next_young_region(NULL);
173 --_length;
174 assert(ret->is_young(), "region should be very young");
176 // Replace 'Survivor' region type with 'Young'. So the region will
177 // be treated as a young region and will not be 'confused' with
178 // newly created survivor regions.
179 if (ret->is_survivor()) {
180 ret->set_young();
181 }
183 if (!ret->is_scan_only()) {
184 return ret;
185 }
187 // scan-only, we'll add it to the scan-only list
188 if (_scan_only_tail == NULL) {
189 guarantee( _scan_only_head == NULL, "invariant" );
191 _scan_only_head = ret;
192 _curr_scan_only = ret;
193 } else {
194 guarantee( _scan_only_head != NULL, "invariant" );
195 _scan_only_tail->set_next_young_region(ret);
196 }
197 guarantee( ret->get_next_young_region() == NULL, "invariant" );
198 _scan_only_tail = ret;
200 // no need to be tagged as scan-only any more
201 ret->set_young();
203 ++_scan_only_length;
204 }
205 assert( length() == 0, "list should be empty" );
206 return NULL;
207 }
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
226 empty_list(_scan_only_head);
227 _scan_only_head = NULL;
228 _scan_only_tail = NULL;
229 _scan_only_length = 0;
230 _curr_scan_only = NULL;
232 empty_list(_survivor_head);
233 _survivor_head = NULL;
234 _survivor_tail = NULL;
235 _survivor_length = 0;
237 _last_sampled_rs_lengths = 0;
239 assert(check_list_empty(false), "just making sure...");
240 }
242 bool YoungList::check_list_well_formed() {
243 bool ret = true;
245 size_t length = 0;
246 HeapRegion* curr = _head;
247 HeapRegion* last = NULL;
248 while (curr != NULL) {
249 if (!curr->is_young() || curr->is_scan_only()) {
250 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
251 "incorrectly tagged (%d, %d)",
252 curr->bottom(), curr->end(),
253 curr->is_young(), curr->is_scan_only());
254 ret = false;
255 }
256 ++length;
257 last = curr;
258 curr = curr->get_next_young_region();
259 }
260 ret = ret && (length == _length);
262 if (!ret) {
263 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
264 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
265 length, _length);
266 }
268 bool scan_only_ret = true;
269 length = 0;
270 curr = _scan_only_head;
271 last = NULL;
272 while (curr != NULL) {
273 if (!curr->is_young() || curr->is_scan_only()) {
274 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
275 "incorrectly tagged (%d, %d)",
276 curr->bottom(), curr->end(),
277 curr->is_young(), curr->is_scan_only());
278 scan_only_ret = false;
279 }
280 ++length;
281 last = curr;
282 curr = curr->get_next_young_region();
283 }
284 scan_only_ret = scan_only_ret && (length == _scan_only_length);
286 if ( (last != _scan_only_tail) ||
287 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
288 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
289 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
290 scan_only_ret = false;
291 }
293 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
294 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
295 scan_only_ret = false;
296 }
298 if (!scan_only_ret) {
299 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
300 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
301 length, _scan_only_length);
302 }
304 return ret && scan_only_ret;
305 }
307 bool YoungList::check_list_empty(bool ignore_scan_only_list,
308 bool check_sample) {
309 bool ret = true;
311 if (_length != 0) {
312 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
313 _length);
314 ret = false;
315 }
316 if (check_sample && _last_sampled_rs_lengths != 0) {
317 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
318 ret = false;
319 }
320 if (_head != NULL) {
321 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
322 ret = false;
323 }
324 if (!ret) {
325 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
326 }
328 if (ignore_scan_only_list)
329 return ret;
331 bool scan_only_ret = true;
332 if (_scan_only_length != 0) {
333 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
334 _scan_only_length);
335 scan_only_ret = false;
336 }
337 if (_scan_only_head != NULL) {
338 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
339 scan_only_ret = false;
340 }
341 if (_scan_only_tail != NULL) {
342 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
343 scan_only_ret = false;
344 }
345 if (!scan_only_ret) {
346 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
347 }
349 return ret && scan_only_ret;
350 }
352 void
353 YoungList::rs_length_sampling_init() {
354 _sampled_rs_lengths = 0;
355 _curr = _head;
356 }
358 bool
359 YoungList::rs_length_sampling_more() {
360 return _curr != NULL;
361 }
363 void
364 YoungList::rs_length_sampling_next() {
365 assert( _curr != NULL, "invariant" );
366 _sampled_rs_lengths += _curr->rem_set()->occupied();
367 _curr = _curr->get_next_young_region();
368 if (_curr == NULL) {
369 _last_sampled_rs_lengths = _sampled_rs_lengths;
370 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
371 }
372 }
374 void
375 YoungList::reset_auxilary_lists() {
376 // We could have just "moved" the scan-only list to the young list.
377 // However, the scan-only list is ordered according to the region
378 // age in descending order, so, by moving one entry at a time, we
379 // ensure that it is recreated in ascending order.
381 guarantee( is_empty(), "young list should be empty" );
382 assert(check_list_well_formed(), "young list should be well formed");
384 // Add survivor regions to SurvRateGroup.
385 _g1h->g1_policy()->note_start_adding_survivor_regions();
386 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
387 for (HeapRegion* curr = _survivor_head;
388 curr != NULL;
389 curr = curr->get_next_young_region()) {
390 _g1h->g1_policy()->set_region_survivors(curr);
391 }
392 _g1h->g1_policy()->note_stop_adding_survivor_regions();
394 if (_survivor_head != NULL) {
395 _head = _survivor_head;
396 _length = _survivor_length + _scan_only_length;
397 _survivor_tail->set_next_young_region(_scan_only_head);
398 } else {
399 _head = _scan_only_head;
400 _length = _scan_only_length;
401 }
403 for (HeapRegion* curr = _scan_only_head;
404 curr != NULL;
405 curr = curr->get_next_young_region()) {
406 curr->recalculate_age_in_surv_rate_group();
407 }
408 _scan_only_head = NULL;
409 _scan_only_tail = NULL;
410 _scan_only_length = 0;
411 _curr_scan_only = NULL;
413 _survivor_head = NULL;
414 _survivor_tail = NULL;
415 _survivor_length = 0;
416 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
418 assert(check_list_well_formed(), "young list should be well formed");
419 }
421 void YoungList::print() {
422 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
423 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
425 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
426 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
427 HeapRegion *curr = lists[list];
428 if (curr == NULL)
429 gclog_or_tty->print_cr(" empty");
430 while (curr != NULL) {
431 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
432 "age: %4d, y: %d, s-o: %d, surv: %d",
433 curr->bottom(), curr->end(),
434 curr->top(),
435 curr->prev_top_at_mark_start(),
436 curr->next_top_at_mark_start(),
437 curr->top_at_conc_mark_count(),
438 curr->age_in_surv_rate_group_cond(),
439 curr->is_young(),
440 curr->is_scan_only(),
441 curr->is_survivor());
442 curr = curr->get_next_young_region();
443 }
444 }
446 gclog_or_tty->print_cr("");
447 }
449 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
450 {
451 // Claim the right to put the region on the dirty cards region list
452 // by installing a self pointer.
453 HeapRegion* next = hr->get_next_dirty_cards_region();
454 if (next == NULL) {
455 HeapRegion* res = (HeapRegion*)
456 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
457 NULL);
458 if (res == NULL) {
459 HeapRegion* head;
460 do {
461 // Put the region to the dirty cards region list.
462 head = _dirty_cards_region_list;
463 next = (HeapRegion*)
464 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
465 if (next == head) {
466 assert(hr->get_next_dirty_cards_region() == hr,
467 "hr->get_next_dirty_cards_region() != hr");
468 if (next == NULL) {
469 // The last region in the list points to itself.
470 hr->set_next_dirty_cards_region(hr);
471 } else {
472 hr->set_next_dirty_cards_region(next);
473 }
474 }
475 } while (next != head);
476 }
477 }
478 }
480 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
481 {
482 HeapRegion* head;
483 HeapRegion* hr;
484 do {
485 head = _dirty_cards_region_list;
486 if (head == NULL) {
487 return NULL;
488 }
489 HeapRegion* new_head = head->get_next_dirty_cards_region();
490 if (head == new_head) {
491 // The last region.
492 new_head = NULL;
493 }
494 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
495 head);
496 } while (hr != head);
497 assert(hr != NULL, "invariant");
498 hr->set_next_dirty_cards_region(NULL);
499 return hr;
500 }
502 void G1CollectedHeap::stop_conc_gc_threads() {
503 _cg1r->stop();
504 _czft->stop();
505 _cmThread->stop();
506 }
509 void G1CollectedHeap::check_ct_logs_at_safepoint() {
510 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
511 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
513 // Count the dirty cards at the start.
514 CountNonCleanMemRegionClosure count1(this);
515 ct_bs->mod_card_iterate(&count1);
516 int orig_count = count1.n();
518 // First clear the logged cards.
519 ClearLoggedCardTableEntryClosure clear;
520 dcqs.set_closure(&clear);
521 dcqs.apply_closure_to_all_completed_buffers();
522 dcqs.iterate_closure_all_threads(false);
523 clear.print_histo();
525 // Now ensure that there's no dirty cards.
526 CountNonCleanMemRegionClosure count2(this);
527 ct_bs->mod_card_iterate(&count2);
528 if (count2.n() != 0) {
529 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
530 count2.n(), orig_count);
531 }
532 guarantee(count2.n() == 0, "Card table should be clean.");
534 RedirtyLoggedCardTableEntryClosure redirty;
535 JavaThread::dirty_card_queue_set().set_closure(&redirty);
536 dcqs.apply_closure_to_all_completed_buffers();
537 dcqs.iterate_closure_all_threads(false);
538 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
539 clear.calls(), orig_count);
540 guarantee(redirty.calls() == clear.calls(),
541 "Or else mechanism is broken.");
543 CountNonCleanMemRegionClosure count3(this);
544 ct_bs->mod_card_iterate(&count3);
545 if (count3.n() != orig_count) {
546 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
547 orig_count, count3.n());
548 guarantee(count3.n() >= orig_count, "Should have restored them all.");
549 }
551 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
552 }
554 // Private class members.
556 G1CollectedHeap* G1CollectedHeap::_g1h;
558 // Private methods.
560 // Finds a HeapRegion that can be used to allocate a given size of block.
563 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
564 bool do_expand,
565 bool zero_filled) {
566 ConcurrentZFThread::note_region_alloc();
567 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
568 if (res == NULL && do_expand) {
569 expand(word_size * HeapWordSize);
570 res = alloc_free_region_from_lists(zero_filled);
571 assert(res == NULL ||
572 (!res->isHumongous() &&
573 (!zero_filled ||
574 res->zero_fill_state() == HeapRegion::Allocated)),
575 "Alloc Regions must be zero filled (and non-H)");
576 }
577 if (res != NULL && res->is_empty()) _free_regions--;
578 assert(res == NULL ||
579 (!res->isHumongous() &&
580 (!zero_filled ||
581 res->zero_fill_state() == HeapRegion::Allocated)),
582 "Non-young alloc Regions must be zero filled (and non-H)");
584 if (G1PrintRegions) {
585 if (res != NULL) {
586 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
587 "top "PTR_FORMAT,
588 res->hrs_index(), res->bottom(), res->end(), res->top());
589 }
590 }
592 return res;
593 }
595 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
596 size_t word_size,
597 bool zero_filled) {
598 HeapRegion* alloc_region = NULL;
599 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
600 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
601 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
602 alloc_region->set_survivor();
603 }
604 ++_gc_alloc_region_counts[purpose];
605 } else {
606 g1_policy()->note_alloc_region_limit_reached(purpose);
607 }
608 return alloc_region;
609 }
611 // If could fit into free regions w/o expansion, try.
612 // Otherwise, if can expand, do so.
613 // Otherwise, if using ex regions might help, try with ex given back.
614 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
615 assert(regions_accounted_for(), "Region leakage!");
617 // We can't allocate H regions while cleanupComplete is running, since
618 // some of the regions we find to be empty might not yet be added to the
619 // unclean list. (If we're already at a safepoint, this call is
620 // unnecessary, not to mention wrong.)
621 if (!SafepointSynchronize::is_at_safepoint())
622 wait_for_cleanup_complete();
624 size_t num_regions =
625 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
627 // Special case if < one region???
629 // Remember the ft size.
630 size_t x_size = expansion_regions();
632 HeapWord* res = NULL;
633 bool eliminated_allocated_from_lists = false;
635 // Can the allocation potentially fit in the free regions?
636 if (free_regions() >= num_regions) {
637 res = _hrs->obj_allocate(word_size);
638 }
639 if (res == NULL) {
640 // Try expansion.
641 size_t fs = _hrs->free_suffix();
642 if (fs + x_size >= num_regions) {
643 expand((num_regions - fs) * HeapRegion::GrainBytes);
644 res = _hrs->obj_allocate(word_size);
645 assert(res != NULL, "This should have worked.");
646 } else {
647 // Expansion won't help. Are there enough free regions if we get rid
648 // of reservations?
649 size_t avail = free_regions();
650 if (avail >= num_regions) {
651 res = _hrs->obj_allocate(word_size);
652 if (res != NULL) {
653 remove_allocated_regions_from_lists();
654 eliminated_allocated_from_lists = true;
655 }
656 }
657 }
658 }
659 if (res != NULL) {
660 // Increment by the number of regions allocated.
661 // FIXME: Assumes regions all of size GrainBytes.
662 #ifndef PRODUCT
663 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
664 HeapRegion::GrainWords));
665 #endif
666 if (!eliminated_allocated_from_lists)
667 remove_allocated_regions_from_lists();
668 _summary_bytes_used += word_size * HeapWordSize;
669 _free_regions -= num_regions;
670 _num_humongous_regions += (int) num_regions;
671 }
672 assert(regions_accounted_for(), "Region Leakage");
673 return res;
674 }
676 HeapWord*
677 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
678 bool permit_collection_pause) {
679 HeapWord* res = NULL;
680 HeapRegion* allocated_young_region = NULL;
682 assert( SafepointSynchronize::is_at_safepoint() ||
683 Heap_lock->owned_by_self(), "pre condition of the call" );
685 if (isHumongous(word_size)) {
686 // Allocation of a humongous object can, in a sense, complete a
687 // partial region, if the previous alloc was also humongous, and
688 // caused the test below to succeed.
689 if (permit_collection_pause)
690 do_collection_pause_if_appropriate(word_size);
691 res = humongousObjAllocate(word_size);
692 assert(_cur_alloc_region == NULL
693 || !_cur_alloc_region->isHumongous(),
694 "Prevent a regression of this bug.");
696 } else {
697 // We may have concurrent cleanup working at the time. Wait for it
698 // to complete. In the future we would probably want to make the
699 // concurrent cleanup truly concurrent by decoupling it from the
700 // allocation.
701 if (!SafepointSynchronize::is_at_safepoint())
702 wait_for_cleanup_complete();
703 // If we do a collection pause, this will be reset to a non-NULL
704 // value. If we don't, nulling here ensures that we allocate a new
705 // region below.
706 if (_cur_alloc_region != NULL) {
707 // We're finished with the _cur_alloc_region.
708 _summary_bytes_used += _cur_alloc_region->used();
709 _cur_alloc_region = NULL;
710 }
711 assert(_cur_alloc_region == NULL, "Invariant.");
712 // Completion of a heap region is perhaps a good point at which to do
713 // a collection pause.
714 if (permit_collection_pause)
715 do_collection_pause_if_appropriate(word_size);
716 // Make sure we have an allocation region available.
717 if (_cur_alloc_region == NULL) {
718 if (!SafepointSynchronize::is_at_safepoint())
719 wait_for_cleanup_complete();
720 bool next_is_young = should_set_young_locked();
721 // If the next region is not young, make sure it's zero-filled.
722 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
723 if (_cur_alloc_region != NULL) {
724 _summary_bytes_used -= _cur_alloc_region->used();
725 if (next_is_young) {
726 set_region_short_lived_locked(_cur_alloc_region);
727 allocated_young_region = _cur_alloc_region;
728 }
729 }
730 }
731 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
732 "Prevent a regression of this bug.");
734 // Now retry the allocation.
735 if (_cur_alloc_region != NULL) {
736 res = _cur_alloc_region->allocate(word_size);
737 }
738 }
740 // NOTE: fails frequently in PRT
741 assert(regions_accounted_for(), "Region leakage!");
743 if (res != NULL) {
744 if (!SafepointSynchronize::is_at_safepoint()) {
745 assert( permit_collection_pause, "invariant" );
746 assert( Heap_lock->owned_by_self(), "invariant" );
747 Heap_lock->unlock();
748 }
750 if (allocated_young_region != NULL) {
751 HeapRegion* hr = allocated_young_region;
752 HeapWord* bottom = hr->bottom();
753 HeapWord* end = hr->end();
754 MemRegion mr(bottom, end);
755 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
756 }
757 }
759 assert( SafepointSynchronize::is_at_safepoint() ||
760 (res == NULL && Heap_lock->owned_by_self()) ||
761 (res != NULL && !Heap_lock->owned_by_self()),
762 "post condition of the call" );
764 return res;
765 }
767 HeapWord*
768 G1CollectedHeap::mem_allocate(size_t word_size,
769 bool is_noref,
770 bool is_tlab,
771 bool* gc_overhead_limit_was_exceeded) {
772 debug_only(check_for_valid_allocation_state());
773 assert(no_gc_in_progress(), "Allocation during gc not allowed");
774 HeapWord* result = NULL;
776 // Loop until the allocation is satisified,
777 // or unsatisfied after GC.
778 for (int try_count = 1; /* return or throw */; try_count += 1) {
779 int gc_count_before;
780 {
781 Heap_lock->lock();
782 result = attempt_allocation(word_size);
783 if (result != NULL) {
784 // attempt_allocation should have unlocked the heap lock
785 assert(is_in(result), "result not in heap");
786 return result;
787 }
788 // Read the gc count while the heap lock is held.
789 gc_count_before = SharedHeap::heap()->total_collections();
790 Heap_lock->unlock();
791 }
793 // Create the garbage collection operation...
794 VM_G1CollectForAllocation op(word_size,
795 gc_count_before);
797 // ...and get the VM thread to execute it.
798 VMThread::execute(&op);
799 if (op.prologue_succeeded()) {
800 result = op.result();
801 assert(result == NULL || is_in(result), "result not in heap");
802 return result;
803 }
805 // Give a warning if we seem to be looping forever.
806 if ((QueuedAllocationWarningCount > 0) &&
807 (try_count % QueuedAllocationWarningCount == 0)) {
808 warning("G1CollectedHeap::mem_allocate_work retries %d times",
809 try_count);
810 }
811 }
812 }
814 void G1CollectedHeap::abandon_cur_alloc_region() {
815 if (_cur_alloc_region != NULL) {
816 // We're finished with the _cur_alloc_region.
817 if (_cur_alloc_region->is_empty()) {
818 _free_regions++;
819 free_region(_cur_alloc_region);
820 } else {
821 _summary_bytes_used += _cur_alloc_region->used();
822 }
823 _cur_alloc_region = NULL;
824 }
825 }
827 void G1CollectedHeap::abandon_gc_alloc_regions() {
828 // first, make sure that the GC alloc region list is empty (it should!)
829 assert(_gc_alloc_region_list == NULL, "invariant");
830 release_gc_alloc_regions(true /* totally */);
831 }
833 class PostMCRemSetClearClosure: public HeapRegionClosure {
834 ModRefBarrierSet* _mr_bs;
835 public:
836 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
837 bool doHeapRegion(HeapRegion* r) {
838 r->reset_gc_time_stamp();
839 if (r->continuesHumongous())
840 return false;
841 HeapRegionRemSet* hrrs = r->rem_set();
842 if (hrrs != NULL) hrrs->clear();
843 // You might think here that we could clear just the cards
844 // corresponding to the used region. But no: if we leave a dirty card
845 // in a region we might allocate into, then it would prevent that card
846 // from being enqueued, and cause it to be missed.
847 // Re: the performance cost: we shouldn't be doing full GC anyway!
848 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
849 return false;
850 }
851 };
854 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
855 ModRefBarrierSet* _mr_bs;
856 public:
857 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
858 bool doHeapRegion(HeapRegion* r) {
859 if (r->continuesHumongous()) return false;
860 if (r->used_region().word_size() != 0) {
861 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
862 }
863 return false;
864 }
865 };
867 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
868 G1CollectedHeap* _g1h;
869 UpdateRSOopClosure _cl;
870 int _worker_i;
871 public:
872 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
873 _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
874 _worker_i(worker_i),
875 _g1h(g1)
876 { }
877 bool doHeapRegion(HeapRegion* r) {
878 if (!r->continuesHumongous()) {
879 _cl.set_from(r);
880 r->oop_iterate(&_cl);
881 }
882 return false;
883 }
884 };
886 class ParRebuildRSTask: public AbstractGangTask {
887 G1CollectedHeap* _g1;
888 public:
889 ParRebuildRSTask(G1CollectedHeap* g1)
890 : AbstractGangTask("ParRebuildRSTask"),
891 _g1(g1)
892 { }
894 void work(int i) {
895 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
896 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
897 HeapRegion::RebuildRSClaimValue);
898 }
899 };
901 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
902 size_t word_size) {
903 ResourceMark rm;
905 if (PrintHeapAtGC) {
906 Universe::print_heap_before_gc();
907 }
909 if (full && DisableExplicitGC) {
910 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
911 return;
912 }
914 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
915 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
917 if (GC_locker::is_active()) {
918 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
919 }
921 {
922 IsGCActiveMark x;
924 // Timing
925 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
926 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
927 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
929 double start = os::elapsedTime();
930 g1_policy()->record_full_collection_start();
932 gc_prologue(true);
933 increment_total_collections(true /* full gc */);
935 size_t g1h_prev_used = used();
936 assert(used() == recalculate_used(), "Should be equal");
938 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
939 HandleMark hm; // Discard invalid handles created during verification
940 prepare_for_verify();
941 gclog_or_tty->print(" VerifyBeforeGC:");
942 Universe::verify(true);
943 }
944 assert(regions_accounted_for(), "Region leakage!");
946 COMPILER2_PRESENT(DerivedPointerTable::clear());
948 // We want to discover references, but not process them yet.
949 // This mode is disabled in
950 // instanceRefKlass::process_discovered_references if the
951 // generation does some collection work, or
952 // instanceRefKlass::enqueue_discovered_references if the
953 // generation returns without doing any work.
954 ref_processor()->disable_discovery();
955 ref_processor()->abandon_partial_discovery();
956 ref_processor()->verify_no_references_recorded();
958 // Abandon current iterations of concurrent marking and concurrent
959 // refinement, if any are in progress.
960 concurrent_mark()->abort();
962 // Make sure we'll choose a new allocation region afterwards.
963 abandon_cur_alloc_region();
964 abandon_gc_alloc_regions();
965 assert(_cur_alloc_region == NULL, "Invariant.");
966 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
967 tear_down_region_lists();
968 set_used_regions_to_need_zero_fill();
969 if (g1_policy()->in_young_gc_mode()) {
970 empty_young_list();
971 g1_policy()->set_full_young_gcs(true);
972 }
974 // Temporarily make reference _discovery_ single threaded (non-MT).
975 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
977 // Temporarily make refs discovery atomic
978 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
980 // Temporarily clear _is_alive_non_header
981 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
983 ref_processor()->enable_discovery();
984 ref_processor()->setup_policy(clear_all_soft_refs);
986 // Do collection work
987 {
988 HandleMark hm; // Discard invalid handles created during gc
989 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
990 }
991 // Because freeing humongous regions may have added some unclean
992 // regions, it is necessary to tear down again before rebuilding.
993 tear_down_region_lists();
994 rebuild_region_lists();
996 _summary_bytes_used = recalculate_used();
998 ref_processor()->enqueue_discovered_references();
1000 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1002 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1003 HandleMark hm; // Discard invalid handles created during verification
1004 gclog_or_tty->print(" VerifyAfterGC:");
1005 prepare_for_verify();
1006 Universe::verify(false);
1007 }
1008 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1010 reset_gc_time_stamp();
1011 // Since everything potentially moved, we will clear all remembered
1012 // sets, and clear all cards. Later we will rebuild remebered
1013 // sets. We will also reset the GC time stamps of the regions.
1014 PostMCRemSetClearClosure rs_clear(mr_bs());
1015 heap_region_iterate(&rs_clear);
1017 // Resize the heap if necessary.
1018 resize_if_necessary_after_full_collection(full ? 0 : word_size);
1020 if (_cg1r->use_cache()) {
1021 _cg1r->clear_and_record_card_counts();
1022 _cg1r->clear_hot_cache();
1023 }
1025 // Rebuild remembered sets of all regions.
1026 if (ParallelGCThreads > 0) {
1027 ParRebuildRSTask rebuild_rs_task(this);
1028 assert(check_heap_region_claim_values(
1029 HeapRegion::InitialClaimValue), "sanity check");
1030 set_par_threads(workers()->total_workers());
1031 workers()->run_task(&rebuild_rs_task);
1032 set_par_threads(0);
1033 assert(check_heap_region_claim_values(
1034 HeapRegion::RebuildRSClaimValue), "sanity check");
1035 reset_heap_region_claim_values();
1036 } else {
1037 RebuildRSOutOfRegionClosure rebuild_rs(this);
1038 heap_region_iterate(&rebuild_rs);
1039 }
1041 if (PrintGC) {
1042 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1043 }
1045 if (true) { // FIXME
1046 // Ask the permanent generation to adjust size for full collections
1047 perm()->compute_new_size();
1048 }
1050 double end = os::elapsedTime();
1051 g1_policy()->record_full_collection_end();
1053 #ifdef TRACESPINNING
1054 ParallelTaskTerminator::print_termination_counts();
1055 #endif
1057 gc_epilogue(true);
1059 // Discard all rset updates
1060 JavaThread::dirty_card_queue_set().abandon_logs();
1061 assert(!G1DeferredRSUpdate
1062 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1063 assert(regions_accounted_for(), "Region leakage!");
1064 }
1066 if (g1_policy()->in_young_gc_mode()) {
1067 _young_list->reset_sampled_info();
1068 assert( check_young_list_empty(false, false),
1069 "young list should be empty at this point");
1070 }
1072 if (PrintHeapAtGC) {
1073 Universe::print_heap_after_gc();
1074 }
1075 }
1077 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1078 do_collection(true, clear_all_soft_refs, 0);
1079 }
1081 // This code is mostly copied from TenuredGeneration.
1082 void
1083 G1CollectedHeap::
1084 resize_if_necessary_after_full_collection(size_t word_size) {
1085 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1087 // Include the current allocation, if any, and bytes that will be
1088 // pre-allocated to support collections, as "used".
1089 const size_t used_after_gc = used();
1090 const size_t capacity_after_gc = capacity();
1091 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1093 // We don't have floating point command-line arguments
1094 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1095 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1096 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1097 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1099 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1100 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1102 // Don't shrink less than the initial size.
1103 minimum_desired_capacity =
1104 MAX2(minimum_desired_capacity,
1105 collector_policy()->initial_heap_byte_size());
1106 maximum_desired_capacity =
1107 MAX2(maximum_desired_capacity,
1108 collector_policy()->initial_heap_byte_size());
1110 // We are failing here because minimum_desired_capacity is
1111 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1112 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1114 if (PrintGC && Verbose) {
1115 const double free_percentage = ((double)free_after_gc) / capacity();
1116 gclog_or_tty->print_cr("Computing new size after full GC ");
1117 gclog_or_tty->print_cr(" "
1118 " minimum_free_percentage: %6.2f",
1119 minimum_free_percentage);
1120 gclog_or_tty->print_cr(" "
1121 " maximum_free_percentage: %6.2f",
1122 maximum_free_percentage);
1123 gclog_or_tty->print_cr(" "
1124 " capacity: %6.1fK"
1125 " minimum_desired_capacity: %6.1fK"
1126 " maximum_desired_capacity: %6.1fK",
1127 capacity() / (double) K,
1128 minimum_desired_capacity / (double) K,
1129 maximum_desired_capacity / (double) K);
1130 gclog_or_tty->print_cr(" "
1131 " free_after_gc : %6.1fK"
1132 " used_after_gc : %6.1fK",
1133 free_after_gc / (double) K,
1134 used_after_gc / (double) K);
1135 gclog_or_tty->print_cr(" "
1136 " free_percentage: %6.2f",
1137 free_percentage);
1138 }
1139 if (capacity() < minimum_desired_capacity) {
1140 // Don't expand unless it's significant
1141 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1142 expand(expand_bytes);
1143 if (PrintGC && Verbose) {
1144 gclog_or_tty->print_cr(" expanding:"
1145 " minimum_desired_capacity: %6.1fK"
1146 " expand_bytes: %6.1fK",
1147 minimum_desired_capacity / (double) K,
1148 expand_bytes / (double) K);
1149 }
1151 // No expansion, now see if we want to shrink
1152 } else if (capacity() > maximum_desired_capacity) {
1153 // Capacity too large, compute shrinking size
1154 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1155 shrink(shrink_bytes);
1156 if (PrintGC && Verbose) {
1157 gclog_or_tty->print_cr(" "
1158 " shrinking:"
1159 " initSize: %.1fK"
1160 " maximum_desired_capacity: %.1fK",
1161 collector_policy()->initial_heap_byte_size() / (double) K,
1162 maximum_desired_capacity / (double) K);
1163 gclog_or_tty->print_cr(" "
1164 " shrink_bytes: %.1fK",
1165 shrink_bytes / (double) K);
1166 }
1167 }
1168 }
1171 HeapWord*
1172 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1173 HeapWord* result = NULL;
1175 // In a G1 heap, we're supposed to keep allocation from failing by
1176 // incremental pauses. Therefore, at least for now, we'll favor
1177 // expansion over collection. (This might change in the future if we can
1178 // do something smarter than full collection to satisfy a failed alloc.)
1180 result = expand_and_allocate(word_size);
1181 if (result != NULL) {
1182 assert(is_in(result), "result not in heap");
1183 return result;
1184 }
1186 // OK, I guess we have to try collection.
1188 do_collection(false, false, word_size);
1190 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1192 if (result != NULL) {
1193 assert(is_in(result), "result not in heap");
1194 return result;
1195 }
1197 // Try collecting soft references.
1198 do_collection(false, true, word_size);
1199 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1200 if (result != NULL) {
1201 assert(is_in(result), "result not in heap");
1202 return result;
1203 }
1205 // What else? We might try synchronous finalization later. If the total
1206 // space available is large enough for the allocation, then a more
1207 // complete compaction phase than we've tried so far might be
1208 // appropriate.
1209 return NULL;
1210 }
1212 // Attempting to expand the heap sufficiently
1213 // to support an allocation of the given "word_size". If
1214 // successful, perform the allocation and return the address of the
1215 // allocated block, or else "NULL".
1217 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1218 size_t expand_bytes = word_size * HeapWordSize;
1219 if (expand_bytes < MinHeapDeltaBytes) {
1220 expand_bytes = MinHeapDeltaBytes;
1221 }
1222 expand(expand_bytes);
1223 assert(regions_accounted_for(), "Region leakage!");
1224 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1225 return result;
1226 }
1228 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1229 size_t pre_used = 0;
1230 size_t cleared_h_regions = 0;
1231 size_t freed_regions = 0;
1232 UncleanRegionList local_list;
1233 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1234 freed_regions, &local_list);
1236 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1237 &local_list);
1238 return pre_used;
1239 }
1241 void
1242 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1243 size_t& pre_used,
1244 size_t& cleared_h,
1245 size_t& freed_regions,
1246 UncleanRegionList* list,
1247 bool par) {
1248 assert(!hr->continuesHumongous(), "should have filtered these out");
1249 size_t res = 0;
1250 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1251 !hr->is_young()) {
1252 if (G1PolicyVerbose > 0)
1253 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1254 " during cleanup", hr, hr->used());
1255 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1256 }
1257 }
1259 // FIXME: both this and shrink could probably be more efficient by
1260 // doing one "VirtualSpace::expand_by" call rather than several.
1261 void G1CollectedHeap::expand(size_t expand_bytes) {
1262 size_t old_mem_size = _g1_storage.committed_size();
1263 // We expand by a minimum of 1K.
1264 expand_bytes = MAX2(expand_bytes, (size_t)K);
1265 size_t aligned_expand_bytes =
1266 ReservedSpace::page_align_size_up(expand_bytes);
1267 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1268 HeapRegion::GrainBytes);
1269 expand_bytes = aligned_expand_bytes;
1270 while (expand_bytes > 0) {
1271 HeapWord* base = (HeapWord*)_g1_storage.high();
1272 // Commit more storage.
1273 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1274 if (!successful) {
1275 expand_bytes = 0;
1276 } else {
1277 expand_bytes -= HeapRegion::GrainBytes;
1278 // Expand the committed region.
1279 HeapWord* high = (HeapWord*) _g1_storage.high();
1280 _g1_committed.set_end(high);
1281 // Create a new HeapRegion.
1282 MemRegion mr(base, high);
1283 bool is_zeroed = !_g1_max_committed.contains(base);
1284 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1286 // Now update max_committed if necessary.
1287 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1289 // Add it to the HeapRegionSeq.
1290 _hrs->insert(hr);
1291 // Set the zero-fill state, according to whether it's already
1292 // zeroed.
1293 {
1294 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1295 if (is_zeroed) {
1296 hr->set_zero_fill_complete();
1297 put_free_region_on_list_locked(hr);
1298 } else {
1299 hr->set_zero_fill_needed();
1300 put_region_on_unclean_list_locked(hr);
1301 }
1302 }
1303 _free_regions++;
1304 // And we used up an expansion region to create it.
1305 _expansion_regions--;
1306 // Tell the cardtable about it.
1307 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1308 // And the offset table as well.
1309 _bot_shared->resize(_g1_committed.word_size());
1310 }
1311 }
1312 if (Verbose && PrintGC) {
1313 size_t new_mem_size = _g1_storage.committed_size();
1314 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1315 old_mem_size/K, aligned_expand_bytes/K,
1316 new_mem_size/K);
1317 }
1318 }
1320 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1321 {
1322 size_t old_mem_size = _g1_storage.committed_size();
1323 size_t aligned_shrink_bytes =
1324 ReservedSpace::page_align_size_down(shrink_bytes);
1325 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1326 HeapRegion::GrainBytes);
1327 size_t num_regions_deleted = 0;
1328 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1330 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1331 if (mr.byte_size() > 0)
1332 _g1_storage.shrink_by(mr.byte_size());
1333 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1335 _g1_committed.set_end(mr.start());
1336 _free_regions -= num_regions_deleted;
1337 _expansion_regions += num_regions_deleted;
1339 // Tell the cardtable about it.
1340 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1342 // And the offset table as well.
1343 _bot_shared->resize(_g1_committed.word_size());
1345 HeapRegionRemSet::shrink_heap(n_regions());
1347 if (Verbose && PrintGC) {
1348 size_t new_mem_size = _g1_storage.committed_size();
1349 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1350 old_mem_size/K, aligned_shrink_bytes/K,
1351 new_mem_size/K);
1352 }
1353 }
1355 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1356 release_gc_alloc_regions(true /* totally */);
1357 tear_down_region_lists(); // We will rebuild them in a moment.
1358 shrink_helper(shrink_bytes);
1359 rebuild_region_lists();
1360 }
1362 // Public methods.
1364 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1365 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1366 #endif // _MSC_VER
1369 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1370 SharedHeap(policy_),
1371 _g1_policy(policy_),
1372 _ref_processor(NULL),
1373 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1374 _bot_shared(NULL),
1375 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1376 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1377 _evac_failure_scan_stack(NULL) ,
1378 _mark_in_progress(false),
1379 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1380 _cur_alloc_region(NULL),
1381 _refine_cte_cl(NULL),
1382 _free_region_list(NULL), _free_region_list_size(0),
1383 _free_regions(0),
1384 _full_collection(false),
1385 _unclean_region_list(),
1386 _unclean_regions_coming(false),
1387 _young_list(new YoungList(this)),
1388 _gc_time_stamp(0),
1389 _surviving_young_words(NULL),
1390 _in_cset_fast_test(NULL),
1391 _in_cset_fast_test_base(NULL),
1392 _dirty_cards_region_list(NULL) {
1393 _g1h = this; // To catch bugs.
1394 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1395 vm_exit_during_initialization("Failed necessary allocation.");
1396 }
1397 int n_queues = MAX2((int)ParallelGCThreads, 1);
1398 _task_queues = new RefToScanQueueSet(n_queues);
1400 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1401 assert(n_rem_sets > 0, "Invariant.");
1403 HeapRegionRemSetIterator** iter_arr =
1404 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1405 for (int i = 0; i < n_queues; i++) {
1406 iter_arr[i] = new HeapRegionRemSetIterator();
1407 }
1408 _rem_set_iterator = iter_arr;
1410 for (int i = 0; i < n_queues; i++) {
1411 RefToScanQueue* q = new RefToScanQueue();
1412 q->initialize();
1413 _task_queues->register_queue(i, q);
1414 }
1416 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1417 _gc_alloc_regions[ap] = NULL;
1418 _gc_alloc_region_counts[ap] = 0;
1419 _retained_gc_alloc_regions[ap] = NULL;
1420 // by default, we do not retain a GC alloc region for each ap;
1421 // we'll override this, when appropriate, below
1422 _retain_gc_alloc_region[ap] = false;
1423 }
1425 // We will try to remember the last half-full tenured region we
1426 // allocated to at the end of a collection so that we can re-use it
1427 // during the next collection.
1428 _retain_gc_alloc_region[GCAllocForTenured] = true;
1430 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1431 }
1433 jint G1CollectedHeap::initialize() {
1434 os::enable_vtime();
1436 // Necessary to satisfy locking discipline assertions.
1438 MutexLocker x(Heap_lock);
1440 // While there are no constraints in the GC code that HeapWordSize
1441 // be any particular value, there are multiple other areas in the
1442 // system which believe this to be true (e.g. oop->object_size in some
1443 // cases incorrectly returns the size in wordSize units rather than
1444 // HeapWordSize).
1445 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1447 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1448 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1450 // Ensure that the sizes are properly aligned.
1451 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1452 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1454 // We allocate this in any case, but only do no work if the command line
1455 // param is off.
1456 _cg1r = new ConcurrentG1Refine();
1458 // Reserve the maximum.
1459 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1460 // Includes the perm-gen.
1462 const size_t total_reserved = max_byte_size + pgs->max_size();
1463 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1465 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1466 HeapRegion::GrainBytes,
1467 false /*ism*/, addr);
1469 if (UseCompressedOops) {
1470 if (addr != NULL && !heap_rs.is_reserved()) {
1471 // Failed to reserve at specified address - the requested memory
1472 // region is taken already, for example, by 'java' launcher.
1473 // Try again to reserver heap higher.
1474 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1475 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1476 false /*ism*/, addr);
1477 if (addr != NULL && !heap_rs0.is_reserved()) {
1478 // Failed to reserve at specified address again - give up.
1479 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1480 assert(addr == NULL, "");
1481 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1482 false /*ism*/, addr);
1483 heap_rs = heap_rs1;
1484 } else {
1485 heap_rs = heap_rs0;
1486 }
1487 }
1488 }
1490 if (!heap_rs.is_reserved()) {
1491 vm_exit_during_initialization("Could not reserve enough space for object heap");
1492 return JNI_ENOMEM;
1493 }
1495 // It is important to do this in a way such that concurrent readers can't
1496 // temporarily think somethings in the heap. (I've actually seen this
1497 // happen in asserts: DLD.)
1498 _reserved.set_word_size(0);
1499 _reserved.set_start((HeapWord*)heap_rs.base());
1500 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1502 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1504 _num_humongous_regions = 0;
1506 // Create the gen rem set (and barrier set) for the entire reserved region.
1507 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1508 set_barrier_set(rem_set()->bs());
1509 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1510 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1511 } else {
1512 vm_exit_during_initialization("G1 requires a mod ref bs.");
1513 return JNI_ENOMEM;
1514 }
1516 // Also create a G1 rem set.
1517 if (G1UseHRIntoRS) {
1518 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1519 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1520 } else {
1521 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1522 return JNI_ENOMEM;
1523 }
1524 } else {
1525 _g1_rem_set = new StupidG1RemSet(this);
1526 }
1528 // Carve out the G1 part of the heap.
1530 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1531 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1532 g1_rs.size()/HeapWordSize);
1533 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1535 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1537 _g1_storage.initialize(g1_rs, 0);
1538 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1539 _g1_max_committed = _g1_committed;
1540 _hrs = new HeapRegionSeq(_expansion_regions);
1541 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1542 guarantee(_cur_alloc_region == NULL, "from constructor");
1544 // 6843694 - ensure that the maximum region index can fit
1545 // in the remembered set structures.
1546 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1547 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1549 const size_t cards_per_region = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift;
1550 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1551 guarantee(cards_per_region < max_cards_per_region, "too many cards per region");
1553 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1554 heap_word_size(init_byte_size));
1556 _g1h = this;
1558 // Create the ConcurrentMark data structure and thread.
1559 // (Must do this late, so that "max_regions" is defined.)
1560 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1561 _cmThread = _cm->cmThread();
1563 // ...and the concurrent zero-fill thread, if necessary.
1564 if (G1ConcZeroFill) {
1565 _czft = new ConcurrentZFThread();
1566 }
1568 // Initialize the from_card cache structure of HeapRegionRemSet.
1569 HeapRegionRemSet::init_heap(max_regions());
1571 // Now expand into the initial heap size.
1572 expand(init_byte_size);
1574 // Perform any initialization actions delegated to the policy.
1575 g1_policy()->init();
1577 g1_policy()->note_start_of_mark_thread();
1579 _refine_cte_cl =
1580 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1581 g1_rem_set(),
1582 concurrent_g1_refine());
1583 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1585 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1586 SATB_Q_FL_lock,
1587 0,
1588 Shared_SATB_Q_lock);
1590 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1591 DirtyCardQ_FL_lock,
1592 G1UpdateBufferQueueMaxLength,
1593 Shared_DirtyCardQ_lock);
1595 if (G1DeferredRSUpdate) {
1596 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1597 DirtyCardQ_FL_lock,
1598 0,
1599 Shared_DirtyCardQ_lock,
1600 &JavaThread::dirty_card_queue_set());
1601 }
1602 // In case we're keeping closure specialization stats, initialize those
1603 // counts and that mechanism.
1604 SpecializationStats::clear();
1606 _gc_alloc_region_list = NULL;
1608 // Do later initialization work for concurrent refinement.
1609 _cg1r->init();
1611 return JNI_OK;
1612 }
1614 void G1CollectedHeap::ref_processing_init() {
1615 SharedHeap::ref_processing_init();
1616 MemRegion mr = reserved_region();
1617 _ref_processor = ReferenceProcessor::create_ref_processor(
1618 mr, // span
1619 false, // Reference discovery is not atomic
1620 // (though it shouldn't matter here.)
1621 true, // mt_discovery
1622 NULL, // is alive closure: need to fill this in for efficiency
1623 ParallelGCThreads,
1624 ParallelRefProcEnabled,
1625 true); // Setting next fields of discovered
1626 // lists requires a barrier.
1627 }
1629 size_t G1CollectedHeap::capacity() const {
1630 return _g1_committed.byte_size();
1631 }
1633 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1634 int worker_i) {
1635 // Clean cards in the hot card cache
1636 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set());
1638 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1639 int n_completed_buffers = 0;
1640 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1641 n_completed_buffers++;
1642 }
1643 g1_policy()->record_update_rs_processed_buffers(worker_i,
1644 (double) n_completed_buffers);
1645 dcqs.clear_n_completed_buffers();
1646 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1647 }
1650 // Computes the sum of the storage used by the various regions.
1652 size_t G1CollectedHeap::used() const {
1653 assert(Heap_lock->owner() != NULL,
1654 "Should be owned on this thread's behalf.");
1655 size_t result = _summary_bytes_used;
1656 // Read only once in case it is set to NULL concurrently
1657 HeapRegion* hr = _cur_alloc_region;
1658 if (hr != NULL)
1659 result += hr->used();
1660 return result;
1661 }
1663 size_t G1CollectedHeap::used_unlocked() const {
1664 size_t result = _summary_bytes_used;
1665 return result;
1666 }
1668 class SumUsedClosure: public HeapRegionClosure {
1669 size_t _used;
1670 public:
1671 SumUsedClosure() : _used(0) {}
1672 bool doHeapRegion(HeapRegion* r) {
1673 if (!r->continuesHumongous()) {
1674 _used += r->used();
1675 }
1676 return false;
1677 }
1678 size_t result() { return _used; }
1679 };
1681 size_t G1CollectedHeap::recalculate_used() const {
1682 SumUsedClosure blk;
1683 _hrs->iterate(&blk);
1684 return blk.result();
1685 }
1687 #ifndef PRODUCT
1688 class SumUsedRegionsClosure: public HeapRegionClosure {
1689 size_t _num;
1690 public:
1691 SumUsedRegionsClosure() : _num(0) {}
1692 bool doHeapRegion(HeapRegion* r) {
1693 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1694 _num += 1;
1695 }
1696 return false;
1697 }
1698 size_t result() { return _num; }
1699 };
1701 size_t G1CollectedHeap::recalculate_used_regions() const {
1702 SumUsedRegionsClosure blk;
1703 _hrs->iterate(&blk);
1704 return blk.result();
1705 }
1706 #endif // PRODUCT
1708 size_t G1CollectedHeap::unsafe_max_alloc() {
1709 if (_free_regions > 0) return HeapRegion::GrainBytes;
1710 // otherwise, is there space in the current allocation region?
1712 // We need to store the current allocation region in a local variable
1713 // here. The problem is that this method doesn't take any locks and
1714 // there may be other threads which overwrite the current allocation
1715 // region field. attempt_allocation(), for example, sets it to NULL
1716 // and this can happen *after* the NULL check here but before the call
1717 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1718 // to be a problem in the optimized build, since the two loads of the
1719 // current allocation region field are optimized away.
1720 HeapRegion* car = _cur_alloc_region;
1722 // FIXME: should iterate over all regions?
1723 if (car == NULL) {
1724 return 0;
1725 }
1726 return car->free();
1727 }
1729 void G1CollectedHeap::collect(GCCause::Cause cause) {
1730 // The caller doesn't have the Heap_lock
1731 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1732 MutexLocker ml(Heap_lock);
1733 collect_locked(cause);
1734 }
1736 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1737 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1738 assert(Heap_lock->is_locked(), "Precondition#2");
1739 GCCauseSetter gcs(this, cause);
1740 switch (cause) {
1741 case GCCause::_heap_inspection:
1742 case GCCause::_heap_dump: {
1743 HandleMark hm;
1744 do_full_collection(false); // don't clear all soft refs
1745 break;
1746 }
1747 default: // XXX FIX ME
1748 ShouldNotReachHere(); // Unexpected use of this function
1749 }
1750 }
1753 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1754 // Don't want to do a GC until cleanup is completed.
1755 wait_for_cleanup_complete();
1757 // Read the GC count while holding the Heap_lock
1758 int gc_count_before = SharedHeap::heap()->total_collections();
1759 {
1760 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1761 VM_G1CollectFull op(gc_count_before, cause);
1762 VMThread::execute(&op);
1763 }
1764 }
1766 bool G1CollectedHeap::is_in(const void* p) const {
1767 if (_g1_committed.contains(p)) {
1768 HeapRegion* hr = _hrs->addr_to_region(p);
1769 return hr->is_in(p);
1770 } else {
1771 return _perm_gen->as_gen()->is_in(p);
1772 }
1773 }
1775 // Iteration functions.
1777 // Iterates an OopClosure over all ref-containing fields of objects
1778 // within a HeapRegion.
1780 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1781 MemRegion _mr;
1782 OopClosure* _cl;
1783 public:
1784 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1785 : _mr(mr), _cl(cl) {}
1786 bool doHeapRegion(HeapRegion* r) {
1787 if (! r->continuesHumongous()) {
1788 r->oop_iterate(_cl);
1789 }
1790 return false;
1791 }
1792 };
1794 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1795 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1796 _hrs->iterate(&blk);
1797 if (do_perm) {
1798 perm_gen()->oop_iterate(cl);
1799 }
1800 }
1802 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1803 IterateOopClosureRegionClosure blk(mr, cl);
1804 _hrs->iterate(&blk);
1805 if (do_perm) {
1806 perm_gen()->oop_iterate(cl);
1807 }
1808 }
1810 // Iterates an ObjectClosure over all objects within a HeapRegion.
1812 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1813 ObjectClosure* _cl;
1814 public:
1815 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1816 bool doHeapRegion(HeapRegion* r) {
1817 if (! r->continuesHumongous()) {
1818 r->object_iterate(_cl);
1819 }
1820 return false;
1821 }
1822 };
1824 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1825 IterateObjectClosureRegionClosure blk(cl);
1826 _hrs->iterate(&blk);
1827 if (do_perm) {
1828 perm_gen()->object_iterate(cl);
1829 }
1830 }
1832 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1833 // FIXME: is this right?
1834 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1835 }
1837 // Calls a SpaceClosure on a HeapRegion.
1839 class SpaceClosureRegionClosure: public HeapRegionClosure {
1840 SpaceClosure* _cl;
1841 public:
1842 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1843 bool doHeapRegion(HeapRegion* r) {
1844 _cl->do_space(r);
1845 return false;
1846 }
1847 };
1849 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1850 SpaceClosureRegionClosure blk(cl);
1851 _hrs->iterate(&blk);
1852 }
1854 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1855 _hrs->iterate(cl);
1856 }
1858 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1859 HeapRegionClosure* cl) {
1860 _hrs->iterate_from(r, cl);
1861 }
1863 void
1864 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1865 _hrs->iterate_from(idx, cl);
1866 }
1868 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1870 void
1871 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1872 int worker,
1873 jint claim_value) {
1874 const size_t regions = n_regions();
1875 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1876 // try to spread out the starting points of the workers
1877 const size_t start_index = regions / worker_num * (size_t) worker;
1879 // each worker will actually look at all regions
1880 for (size_t count = 0; count < regions; ++count) {
1881 const size_t index = (start_index + count) % regions;
1882 assert(0 <= index && index < regions, "sanity");
1883 HeapRegion* r = region_at(index);
1884 // we'll ignore "continues humongous" regions (we'll process them
1885 // when we come across their corresponding "start humongous"
1886 // region) and regions already claimed
1887 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1888 continue;
1889 }
1890 // OK, try to claim it
1891 if (r->claimHeapRegion(claim_value)) {
1892 // success!
1893 assert(!r->continuesHumongous(), "sanity");
1894 if (r->startsHumongous()) {
1895 // If the region is "starts humongous" we'll iterate over its
1896 // "continues humongous" first; in fact we'll do them
1897 // first. The order is important. In on case, calling the
1898 // closure on the "starts humongous" region might de-allocate
1899 // and clear all its "continues humongous" regions and, as a
1900 // result, we might end up processing them twice. So, we'll do
1901 // them first (notice: most closures will ignore them anyway) and
1902 // then we'll do the "starts humongous" region.
1903 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1904 HeapRegion* chr = region_at(ch_index);
1906 // if the region has already been claimed or it's not
1907 // "continues humongous" we're done
1908 if (chr->claim_value() == claim_value ||
1909 !chr->continuesHumongous()) {
1910 break;
1911 }
1913 // Noone should have claimed it directly. We can given
1914 // that we claimed its "starts humongous" region.
1915 assert(chr->claim_value() != claim_value, "sanity");
1916 assert(chr->humongous_start_region() == r, "sanity");
1918 if (chr->claimHeapRegion(claim_value)) {
1919 // we should always be able to claim it; noone else should
1920 // be trying to claim this region
1922 bool res2 = cl->doHeapRegion(chr);
1923 assert(!res2, "Should not abort");
1925 // Right now, this holds (i.e., no closure that actually
1926 // does something with "continues humongous" regions
1927 // clears them). We might have to weaken it in the future,
1928 // but let's leave these two asserts here for extra safety.
1929 assert(chr->continuesHumongous(), "should still be the case");
1930 assert(chr->humongous_start_region() == r, "sanity");
1931 } else {
1932 guarantee(false, "we should not reach here");
1933 }
1934 }
1935 }
1937 assert(!r->continuesHumongous(), "sanity");
1938 bool res = cl->doHeapRegion(r);
1939 assert(!res, "Should not abort");
1940 }
1941 }
1942 }
1944 class ResetClaimValuesClosure: public HeapRegionClosure {
1945 public:
1946 bool doHeapRegion(HeapRegion* r) {
1947 r->set_claim_value(HeapRegion::InitialClaimValue);
1948 return false;
1949 }
1950 };
1952 void
1953 G1CollectedHeap::reset_heap_region_claim_values() {
1954 ResetClaimValuesClosure blk;
1955 heap_region_iterate(&blk);
1956 }
1958 #ifdef ASSERT
1959 // This checks whether all regions in the heap have the correct claim
1960 // value. I also piggy-backed on this a check to ensure that the
1961 // humongous_start_region() information on "continues humongous"
1962 // regions is correct.
1964 class CheckClaimValuesClosure : public HeapRegionClosure {
1965 private:
1966 jint _claim_value;
1967 size_t _failures;
1968 HeapRegion* _sh_region;
1969 public:
1970 CheckClaimValuesClosure(jint claim_value) :
1971 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1972 bool doHeapRegion(HeapRegion* r) {
1973 if (r->claim_value() != _claim_value) {
1974 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1975 "claim value = %d, should be %d",
1976 r->bottom(), r->end(), r->claim_value(),
1977 _claim_value);
1978 ++_failures;
1979 }
1980 if (!r->isHumongous()) {
1981 _sh_region = NULL;
1982 } else if (r->startsHumongous()) {
1983 _sh_region = r;
1984 } else if (r->continuesHumongous()) {
1985 if (r->humongous_start_region() != _sh_region) {
1986 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1987 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1988 r->bottom(), r->end(),
1989 r->humongous_start_region(),
1990 _sh_region);
1991 ++_failures;
1992 }
1993 }
1994 return false;
1995 }
1996 size_t failures() {
1997 return _failures;
1998 }
1999 };
2001 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2002 CheckClaimValuesClosure cl(claim_value);
2003 heap_region_iterate(&cl);
2004 return cl.failures() == 0;
2005 }
2006 #endif // ASSERT
2008 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2009 HeapRegion* r = g1_policy()->collection_set();
2010 while (r != NULL) {
2011 HeapRegion* next = r->next_in_collection_set();
2012 if (cl->doHeapRegion(r)) {
2013 cl->incomplete();
2014 return;
2015 }
2016 r = next;
2017 }
2018 }
2020 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2021 HeapRegionClosure *cl) {
2022 assert(r->in_collection_set(),
2023 "Start region must be a member of the collection set.");
2024 HeapRegion* cur = r;
2025 while (cur != NULL) {
2026 HeapRegion* next = cur->next_in_collection_set();
2027 if (cl->doHeapRegion(cur) && false) {
2028 cl->incomplete();
2029 return;
2030 }
2031 cur = next;
2032 }
2033 cur = g1_policy()->collection_set();
2034 while (cur != r) {
2035 HeapRegion* next = cur->next_in_collection_set();
2036 if (cl->doHeapRegion(cur) && false) {
2037 cl->incomplete();
2038 return;
2039 }
2040 cur = next;
2041 }
2042 }
2044 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2045 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2046 }
2049 Space* G1CollectedHeap::space_containing(const void* addr) const {
2050 Space* res = heap_region_containing(addr);
2051 if (res == NULL)
2052 res = perm_gen()->space_containing(addr);
2053 return res;
2054 }
2056 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2057 Space* sp = space_containing(addr);
2058 if (sp != NULL) {
2059 return sp->block_start(addr);
2060 }
2061 return NULL;
2062 }
2064 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2065 Space* sp = space_containing(addr);
2066 assert(sp != NULL, "block_size of address outside of heap");
2067 return sp->block_size(addr);
2068 }
2070 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2071 Space* sp = space_containing(addr);
2072 return sp->block_is_obj(addr);
2073 }
2075 bool G1CollectedHeap::supports_tlab_allocation() const {
2076 return true;
2077 }
2079 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2080 return HeapRegion::GrainBytes;
2081 }
2083 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2084 // Return the remaining space in the cur alloc region, but not less than
2085 // the min TLAB size.
2086 // Also, no more than half the region size, since we can't allow tlabs to
2087 // grow big enough to accomodate humongous objects.
2089 // We need to story it locally, since it might change between when we
2090 // test for NULL and when we use it later.
2091 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2092 if (cur_alloc_space == NULL) {
2093 return HeapRegion::GrainBytes/2;
2094 } else {
2095 return MAX2(MIN2(cur_alloc_space->free(),
2096 (size_t)(HeapRegion::GrainBytes/2)),
2097 (size_t)MinTLABSize);
2098 }
2099 }
2101 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2102 bool dummy;
2103 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2104 }
2106 bool G1CollectedHeap::allocs_are_zero_filled() {
2107 return false;
2108 }
2110 size_t G1CollectedHeap::large_typearray_limit() {
2111 // FIXME
2112 return HeapRegion::GrainBytes/HeapWordSize;
2113 }
2115 size_t G1CollectedHeap::max_capacity() const {
2116 return _g1_committed.byte_size();
2117 }
2119 jlong G1CollectedHeap::millis_since_last_gc() {
2120 // assert(false, "NYI");
2121 return 0;
2122 }
2125 void G1CollectedHeap::prepare_for_verify() {
2126 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2127 ensure_parsability(false);
2128 }
2129 g1_rem_set()->prepare_for_verify();
2130 }
2132 class VerifyLivenessOopClosure: public OopClosure {
2133 G1CollectedHeap* g1h;
2134 public:
2135 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2136 g1h = _g1h;
2137 }
2138 void do_oop(narrowOop *p) { do_oop_work(p); }
2139 void do_oop( oop *p) { do_oop_work(p); }
2141 template <class T> void do_oop_work(T *p) {
2142 oop obj = oopDesc::load_decode_heap_oop(p);
2143 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2144 "Dead object referenced by a not dead object");
2145 }
2146 };
2148 class VerifyObjsInRegionClosure: public ObjectClosure {
2149 private:
2150 G1CollectedHeap* _g1h;
2151 size_t _live_bytes;
2152 HeapRegion *_hr;
2153 bool _use_prev_marking;
2154 public:
2155 // use_prev_marking == true -> use "prev" marking information,
2156 // use_prev_marking == false -> use "next" marking information
2157 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2158 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2159 _g1h = G1CollectedHeap::heap();
2160 }
2161 void do_object(oop o) {
2162 VerifyLivenessOopClosure isLive(_g1h);
2163 assert(o != NULL, "Huh?");
2164 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2165 o->oop_iterate(&isLive);
2166 if (!_hr->obj_allocated_since_prev_marking(o))
2167 _live_bytes += (o->size() * HeapWordSize);
2168 }
2169 }
2170 size_t live_bytes() { return _live_bytes; }
2171 };
2173 class PrintObjsInRegionClosure : public ObjectClosure {
2174 HeapRegion *_hr;
2175 G1CollectedHeap *_g1;
2176 public:
2177 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2178 _g1 = G1CollectedHeap::heap();
2179 };
2181 void do_object(oop o) {
2182 if (o != NULL) {
2183 HeapWord *start = (HeapWord *) o;
2184 size_t word_sz = o->size();
2185 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2186 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2187 (void*) o, word_sz,
2188 _g1->isMarkedPrev(o),
2189 _g1->isMarkedNext(o),
2190 _hr->obj_allocated_since_prev_marking(o));
2191 HeapWord *end = start + word_sz;
2192 HeapWord *cur;
2193 int *val;
2194 for (cur = start; cur < end; cur++) {
2195 val = (int *) cur;
2196 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2197 }
2198 }
2199 }
2200 };
2202 class VerifyRegionClosure: public HeapRegionClosure {
2203 private:
2204 bool _allow_dirty;
2205 bool _par;
2206 bool _use_prev_marking;
2207 public:
2208 // use_prev_marking == true -> use "prev" marking information,
2209 // use_prev_marking == false -> use "next" marking information
2210 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2211 : _allow_dirty(allow_dirty),
2212 _par(par),
2213 _use_prev_marking(use_prev_marking) {}
2215 bool doHeapRegion(HeapRegion* r) {
2216 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2217 "Should be unclaimed at verify points.");
2218 if (!r->continuesHumongous()) {
2219 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2220 r->verify(_allow_dirty, _use_prev_marking);
2221 r->object_iterate(¬_dead_yet_cl);
2222 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2223 "More live objects than counted in last complete marking.");
2224 }
2225 return false;
2226 }
2227 };
2229 class VerifyRootsClosure: public OopsInGenClosure {
2230 private:
2231 G1CollectedHeap* _g1h;
2232 bool _failures;
2233 bool _use_prev_marking;
2234 public:
2235 // use_prev_marking == true -> use "prev" marking information,
2236 // use_prev_marking == false -> use "next" marking information
2237 VerifyRootsClosure(bool use_prev_marking) :
2238 _g1h(G1CollectedHeap::heap()),
2239 _failures(false),
2240 _use_prev_marking(use_prev_marking) { }
2242 bool failures() { return _failures; }
2244 template <class T> void do_oop_nv(T* p) {
2245 T heap_oop = oopDesc::load_heap_oop(p);
2246 if (!oopDesc::is_null(heap_oop)) {
2247 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2248 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2249 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2250 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2251 obj->print_on(gclog_or_tty);
2252 _failures = true;
2253 }
2254 }
2255 }
2257 void do_oop(oop* p) { do_oop_nv(p); }
2258 void do_oop(narrowOop* p) { do_oop_nv(p); }
2259 };
2261 // This is the task used for parallel heap verification.
2263 class G1ParVerifyTask: public AbstractGangTask {
2264 private:
2265 G1CollectedHeap* _g1h;
2266 bool _allow_dirty;
2267 bool _use_prev_marking;
2269 public:
2270 // use_prev_marking == true -> use "prev" marking information,
2271 // use_prev_marking == false -> use "next" marking information
2272 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2273 bool use_prev_marking) :
2274 AbstractGangTask("Parallel verify task"),
2275 _g1h(g1h),
2276 _allow_dirty(allow_dirty),
2277 _use_prev_marking(use_prev_marking) { }
2279 void work(int worker_i) {
2280 HandleMark hm;
2281 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2282 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2283 HeapRegion::ParVerifyClaimValue);
2284 }
2285 };
2287 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2288 verify(allow_dirty, silent, /* use_prev_marking */ true);
2289 }
2291 void G1CollectedHeap::verify(bool allow_dirty,
2292 bool silent,
2293 bool use_prev_marking) {
2294 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2295 if (!silent) { gclog_or_tty->print("roots "); }
2296 VerifyRootsClosure rootsCl(use_prev_marking);
2297 process_strong_roots(false,
2298 SharedHeap::SO_AllClasses,
2299 &rootsCl,
2300 &rootsCl);
2301 rem_set()->invalidate(perm_gen()->used_region(), false);
2302 if (!silent) { gclog_or_tty->print("heapRegions "); }
2303 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2304 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2305 "sanity check");
2307 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2308 int n_workers = workers()->total_workers();
2309 set_par_threads(n_workers);
2310 workers()->run_task(&task);
2311 set_par_threads(0);
2313 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2314 "sanity check");
2316 reset_heap_region_claim_values();
2318 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2319 "sanity check");
2320 } else {
2321 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2322 _hrs->iterate(&blk);
2323 }
2324 if (!silent) gclog_or_tty->print("remset ");
2325 rem_set()->verify();
2326 guarantee(!rootsCl.failures(), "should not have had failures");
2327 } else {
2328 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2329 }
2330 }
2332 class PrintRegionClosure: public HeapRegionClosure {
2333 outputStream* _st;
2334 public:
2335 PrintRegionClosure(outputStream* st) : _st(st) {}
2336 bool doHeapRegion(HeapRegion* r) {
2337 r->print_on(_st);
2338 return false;
2339 }
2340 };
2342 void G1CollectedHeap::print() const { print_on(tty); }
2344 void G1CollectedHeap::print_on(outputStream* st) const {
2345 print_on(st, PrintHeapAtGCExtended);
2346 }
2348 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2349 st->print(" %-20s", "garbage-first heap");
2350 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2351 capacity()/K, used_unlocked()/K);
2352 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2353 _g1_storage.low_boundary(),
2354 _g1_storage.high(),
2355 _g1_storage.high_boundary());
2356 st->cr();
2357 st->print(" region size " SIZE_FORMAT "K, ",
2358 HeapRegion::GrainBytes/K);
2359 size_t young_regions = _young_list->length();
2360 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2361 young_regions, young_regions * HeapRegion::GrainBytes / K);
2362 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2363 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2364 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2365 st->cr();
2366 perm()->as_gen()->print_on(st);
2367 if (extended) {
2368 print_on_extended(st);
2369 }
2370 }
2372 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2373 PrintRegionClosure blk(st);
2374 _hrs->iterate(&blk);
2375 }
2377 class PrintOnThreadsClosure : public ThreadClosure {
2378 outputStream* _st;
2379 public:
2380 PrintOnThreadsClosure(outputStream* st) : _st(st) { }
2381 virtual void do_thread(Thread *t) {
2382 t->print_on(_st);
2383 }
2384 };
2386 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2387 if (ParallelGCThreads > 0) {
2388 workers()->print_worker_threads();
2389 }
2390 st->print("\"G1 concurrent mark GC Thread\" ");
2391 _cmThread->print();
2392 st->cr();
2393 st->print("\"G1 concurrent refinement GC Threads\" ");
2394 PrintOnThreadsClosure p(st);
2395 _cg1r->threads_do(&p);
2396 st->cr();
2397 st->print("\"G1 zero-fill GC Thread\" ");
2398 _czft->print_on(st);
2399 st->cr();
2400 }
2402 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2403 if (ParallelGCThreads > 0) {
2404 workers()->threads_do(tc);
2405 }
2406 tc->do_thread(_cmThread);
2407 _cg1r->threads_do(tc);
2408 tc->do_thread(_czft);
2409 }
2411 void G1CollectedHeap::print_tracing_info() const {
2412 // We'll overload this to mean "trace GC pause statistics."
2413 if (TraceGen0Time || TraceGen1Time) {
2414 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2415 // to that.
2416 g1_policy()->print_tracing_info();
2417 }
2418 if (G1SummarizeRSetStats) {
2419 g1_rem_set()->print_summary_info();
2420 }
2421 if (G1SummarizeConcurrentMark) {
2422 concurrent_mark()->print_summary_info();
2423 }
2424 if (G1SummarizeZFStats) {
2425 ConcurrentZFThread::print_summary_info();
2426 }
2427 g1_policy()->print_yg_surv_rate_info();
2429 SpecializationStats::print();
2430 }
2433 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2434 HeapRegion* hr = heap_region_containing(addr);
2435 if (hr == NULL) {
2436 return 0;
2437 } else {
2438 return 1;
2439 }
2440 }
2442 G1CollectedHeap* G1CollectedHeap::heap() {
2443 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2444 "not a garbage-first heap");
2445 return _g1h;
2446 }
2448 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2449 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2450 // Call allocation profiler
2451 AllocationProfiler::iterate_since_last_gc();
2452 // Fill TLAB's and such
2453 ensure_parsability(true);
2454 }
2456 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2457 // FIXME: what is this about?
2458 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2459 // is set.
2460 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2461 "derived pointer present"));
2462 }
2464 void G1CollectedHeap::do_collection_pause() {
2465 // Read the GC count while holding the Heap_lock
2466 // we need to do this _before_ wait_for_cleanup_complete(), to
2467 // ensure that we do not give up the heap lock and potentially
2468 // pick up the wrong count
2469 int gc_count_before = SharedHeap::heap()->total_collections();
2471 // Don't want to do a GC pause while cleanup is being completed!
2472 wait_for_cleanup_complete();
2474 g1_policy()->record_stop_world_start();
2475 {
2476 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2477 VM_G1IncCollectionPause op(gc_count_before);
2478 VMThread::execute(&op);
2479 }
2480 }
2482 void
2483 G1CollectedHeap::doConcurrentMark() {
2484 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2485 if (!_cmThread->in_progress()) {
2486 _cmThread->set_started();
2487 CGC_lock->notify();
2488 }
2489 }
2491 class VerifyMarkedObjsClosure: public ObjectClosure {
2492 G1CollectedHeap* _g1h;
2493 public:
2494 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2495 void do_object(oop obj) {
2496 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2497 "markandsweep mark should agree with concurrent deadness");
2498 }
2499 };
2501 void
2502 G1CollectedHeap::checkConcurrentMark() {
2503 VerifyMarkedObjsClosure verifycl(this);
2504 // MutexLockerEx x(getMarkBitMapLock(),
2505 // Mutex::_no_safepoint_check_flag);
2506 object_iterate(&verifycl, false);
2507 }
2509 void G1CollectedHeap::do_sync_mark() {
2510 _cm->checkpointRootsInitial();
2511 _cm->markFromRoots();
2512 _cm->checkpointRootsFinal(false);
2513 }
2515 // <NEW PREDICTION>
2517 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2518 bool young) {
2519 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2520 }
2522 void G1CollectedHeap::check_if_region_is_too_expensive(double
2523 predicted_time_ms) {
2524 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2525 }
2527 size_t G1CollectedHeap::pending_card_num() {
2528 size_t extra_cards = 0;
2529 JavaThread *curr = Threads::first();
2530 while (curr != NULL) {
2531 DirtyCardQueue& dcq = curr->dirty_card_queue();
2532 extra_cards += dcq.size();
2533 curr = curr->next();
2534 }
2535 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2536 size_t buffer_size = dcqs.buffer_size();
2537 size_t buffer_num = dcqs.completed_buffers_num();
2538 return buffer_size * buffer_num + extra_cards;
2539 }
2541 size_t G1CollectedHeap::max_pending_card_num() {
2542 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2543 size_t buffer_size = dcqs.buffer_size();
2544 size_t buffer_num = dcqs.completed_buffers_num();
2545 int thread_num = Threads::number_of_threads();
2546 return (buffer_num + thread_num) * buffer_size;
2547 }
2549 size_t G1CollectedHeap::cards_scanned() {
2550 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2551 return g1_rset->cardsScanned();
2552 }
2554 void
2555 G1CollectedHeap::setup_surviving_young_words() {
2556 guarantee( _surviving_young_words == NULL, "pre-condition" );
2557 size_t array_length = g1_policy()->young_cset_length();
2558 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2559 if (_surviving_young_words == NULL) {
2560 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2561 "Not enough space for young surv words summary.");
2562 }
2563 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2564 #ifdef ASSERT
2565 for (size_t i = 0; i < array_length; ++i) {
2566 assert( _surviving_young_words[i] == 0, "memset above" );
2567 }
2568 #endif // !ASSERT
2569 }
2571 void
2572 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2573 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2574 size_t array_length = g1_policy()->young_cset_length();
2575 for (size_t i = 0; i < array_length; ++i)
2576 _surviving_young_words[i] += surv_young_words[i];
2577 }
2579 void
2580 G1CollectedHeap::cleanup_surviving_young_words() {
2581 guarantee( _surviving_young_words != NULL, "pre-condition" );
2582 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2583 _surviving_young_words = NULL;
2584 }
2586 // </NEW PREDICTION>
2588 void
2589 G1CollectedHeap::do_collection_pause_at_safepoint() {
2590 if (PrintHeapAtGC) {
2591 Universe::print_heap_before_gc();
2592 }
2594 {
2595 char verbose_str[128];
2596 sprintf(verbose_str, "GC pause ");
2597 if (g1_policy()->in_young_gc_mode()) {
2598 if (g1_policy()->full_young_gcs())
2599 strcat(verbose_str, "(young)");
2600 else
2601 strcat(verbose_str, "(partial)");
2602 }
2603 if (g1_policy()->should_initiate_conc_mark())
2604 strcat(verbose_str, " (initial-mark)");
2606 GCCauseSetter x(this, GCCause::_g1_inc_collection_pause);
2608 // if PrintGCDetails is on, we'll print long statistics information
2609 // in the collector policy code, so let's not print this as the output
2610 // is messy if we do.
2611 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2612 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2613 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2615 ResourceMark rm;
2616 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2617 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2618 guarantee(!is_gc_active(), "collection is not reentrant");
2619 assert(regions_accounted_for(), "Region leakage!");
2621 increment_gc_time_stamp();
2623 if (g1_policy()->in_young_gc_mode()) {
2624 assert(check_young_list_well_formed(),
2625 "young list should be well formed");
2626 }
2628 if (GC_locker::is_active()) {
2629 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2630 }
2632 bool abandoned = false;
2633 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2634 IsGCActiveMark x;
2636 gc_prologue(false);
2637 increment_total_collections(false /* full gc */);
2639 #if G1_REM_SET_LOGGING
2640 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2641 print();
2642 #endif
2644 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2645 HandleMark hm; // Discard invalid handles created during verification
2646 prepare_for_verify();
2647 gclog_or_tty->print(" VerifyBeforeGC:");
2648 Universe::verify(false);
2649 }
2651 COMPILER2_PRESENT(DerivedPointerTable::clear());
2653 // We want to turn off ref discovery, if necessary, and turn it back on
2654 // on again later if we do. XXX Dubious: why is discovery disabled?
2655 bool was_enabled = ref_processor()->discovery_enabled();
2656 if (was_enabled) ref_processor()->disable_discovery();
2658 // Forget the current alloc region (we might even choose it to be part
2659 // of the collection set!).
2660 abandon_cur_alloc_region();
2662 // The elapsed time induced by the start time below deliberately elides
2663 // the possible verification above.
2664 double start_time_sec = os::elapsedTime();
2665 size_t start_used_bytes = used();
2667 g1_policy()->record_collection_pause_start(start_time_sec,
2668 start_used_bytes);
2670 guarantee(_in_cset_fast_test == NULL, "invariant");
2671 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2672 _in_cset_fast_test_length = max_regions();
2673 _in_cset_fast_test_base =
2674 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2675 memset(_in_cset_fast_test_base, false,
2676 _in_cset_fast_test_length * sizeof(bool));
2677 // We're biasing _in_cset_fast_test to avoid subtracting the
2678 // beginning of the heap every time we want to index; basically
2679 // it's the same with what we do with the card table.
2680 _in_cset_fast_test = _in_cset_fast_test_base -
2681 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2683 #if SCAN_ONLY_VERBOSE
2684 _young_list->print();
2685 #endif // SCAN_ONLY_VERBOSE
2687 if (g1_policy()->should_initiate_conc_mark()) {
2688 concurrent_mark()->checkpointRootsInitialPre();
2689 }
2690 save_marks();
2692 // We must do this before any possible evacuation that should propagate
2693 // marks.
2694 if (mark_in_progress()) {
2695 double start_time_sec = os::elapsedTime();
2697 _cm->drainAllSATBBuffers();
2698 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2699 g1_policy()->record_satb_drain_time(finish_mark_ms);
2700 }
2701 // Record the number of elements currently on the mark stack, so we
2702 // only iterate over these. (Since evacuation may add to the mark
2703 // stack, doing more exposes race conditions.) If no mark is in
2704 // progress, this will be zero.
2705 _cm->set_oops_do_bound();
2707 assert(regions_accounted_for(), "Region leakage.");
2709 if (mark_in_progress())
2710 concurrent_mark()->newCSet();
2712 // Now choose the CS.
2713 g1_policy()->choose_collection_set();
2715 // We may abandon a pause if we find no region that will fit in the MMU
2716 // pause.
2717 bool abandoned = (g1_policy()->collection_set() == NULL);
2719 // Nothing to do if we were unable to choose a collection set.
2720 if (!abandoned) {
2721 #if G1_REM_SET_LOGGING
2722 gclog_or_tty->print_cr("\nAfter pause, heap:");
2723 print();
2724 #endif
2726 setup_surviving_young_words();
2728 // Set up the gc allocation regions.
2729 get_gc_alloc_regions();
2731 // Actually do the work...
2732 evacuate_collection_set();
2733 free_collection_set(g1_policy()->collection_set());
2734 g1_policy()->clear_collection_set();
2736 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2737 // this is more for peace of mind; we're nulling them here and
2738 // we're expecting them to be null at the beginning of the next GC
2739 _in_cset_fast_test = NULL;
2740 _in_cset_fast_test_base = NULL;
2742 cleanup_surviving_young_words();
2744 if (g1_policy()->in_young_gc_mode()) {
2745 _young_list->reset_sampled_info();
2746 assert(check_young_list_empty(true),
2747 "young list should be empty");
2749 #if SCAN_ONLY_VERBOSE
2750 _young_list->print();
2751 #endif // SCAN_ONLY_VERBOSE
2753 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2754 _young_list->first_survivor_region(),
2755 _young_list->last_survivor_region());
2756 _young_list->reset_auxilary_lists();
2757 }
2758 } else {
2759 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2760 }
2762 if (evacuation_failed()) {
2763 _summary_bytes_used = recalculate_used();
2764 } else {
2765 // The "used" of the the collection set have already been subtracted
2766 // when they were freed. Add in the bytes evacuated.
2767 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2768 }
2770 if (g1_policy()->in_young_gc_mode() &&
2771 g1_policy()->should_initiate_conc_mark()) {
2772 concurrent_mark()->checkpointRootsInitialPost();
2773 set_marking_started();
2774 // CAUTION: after the doConcurrentMark() call below,
2775 // the concurrent marking thread(s) could be running
2776 // concurrently with us. Make sure that anything after
2777 // this point does not assume that we are the only GC thread
2778 // running. Note: of course, the actual marking work will
2779 // not start until the safepoint itself is released in
2780 // ConcurrentGCThread::safepoint_desynchronize().
2781 doConcurrentMark();
2782 }
2784 #if SCAN_ONLY_VERBOSE
2785 _young_list->print();
2786 #endif // SCAN_ONLY_VERBOSE
2788 double end_time_sec = os::elapsedTime();
2789 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2790 g1_policy()->record_pause_time_ms(pause_time_ms);
2791 g1_policy()->record_collection_pause_end(abandoned);
2793 assert(regions_accounted_for(), "Region leakage.");
2795 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2796 HandleMark hm; // Discard invalid handles created during verification
2797 gclog_or_tty->print(" VerifyAfterGC:");
2798 prepare_for_verify();
2799 Universe::verify(false);
2800 }
2802 if (was_enabled) ref_processor()->enable_discovery();
2804 {
2805 size_t expand_bytes = g1_policy()->expansion_amount();
2806 if (expand_bytes > 0) {
2807 size_t bytes_before = capacity();
2808 expand(expand_bytes);
2809 }
2810 }
2812 if (mark_in_progress()) {
2813 concurrent_mark()->update_g1_committed();
2814 }
2816 #ifdef TRACESPINNING
2817 ParallelTaskTerminator::print_termination_counts();
2818 #endif
2820 gc_epilogue(false);
2821 }
2823 assert(verify_region_lists(), "Bad region lists.");
2825 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2826 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2827 print_tracing_info();
2828 vm_exit(-1);
2829 }
2830 }
2832 if (PrintHeapAtGC) {
2833 Universe::print_heap_after_gc();
2834 }
2835 if (G1SummarizeRSetStats &&
2836 (G1SummarizeRSetStatsPeriod > 0) &&
2837 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
2838 g1_rem_set()->print_summary_info();
2839 }
2840 }
2842 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2843 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2844 // make sure we don't call set_gc_alloc_region() multiple times on
2845 // the same region
2846 assert(r == NULL || !r->is_gc_alloc_region(),
2847 "shouldn't already be a GC alloc region");
2848 HeapWord* original_top = NULL;
2849 if (r != NULL)
2850 original_top = r->top();
2852 // We will want to record the used space in r as being there before gc.
2853 // One we install it as a GC alloc region it's eligible for allocation.
2854 // So record it now and use it later.
2855 size_t r_used = 0;
2856 if (r != NULL) {
2857 r_used = r->used();
2859 if (ParallelGCThreads > 0) {
2860 // need to take the lock to guard against two threads calling
2861 // get_gc_alloc_region concurrently (very unlikely but...)
2862 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2863 r->save_marks();
2864 }
2865 }
2866 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2867 _gc_alloc_regions[purpose] = r;
2868 if (old_alloc_region != NULL) {
2869 // Replace aliases too.
2870 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2871 if (_gc_alloc_regions[ap] == old_alloc_region) {
2872 _gc_alloc_regions[ap] = r;
2873 }
2874 }
2875 }
2876 if (r != NULL) {
2877 push_gc_alloc_region(r);
2878 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2879 // We are using a region as a GC alloc region after it has been used
2880 // as a mutator allocation region during the current marking cycle.
2881 // The mutator-allocated objects are currently implicitly marked, but
2882 // when we move hr->next_top_at_mark_start() forward at the the end
2883 // of the GC pause, they won't be. We therefore mark all objects in
2884 // the "gap". We do this object-by-object, since marking densely
2885 // does not currently work right with marking bitmap iteration. This
2886 // means we rely on TLAB filling at the start of pauses, and no
2887 // "resuscitation" of filled TLAB's. If we want to do this, we need
2888 // to fix the marking bitmap iteration.
2889 HeapWord* curhw = r->next_top_at_mark_start();
2890 HeapWord* t = original_top;
2892 while (curhw < t) {
2893 oop cur = (oop)curhw;
2894 // We'll assume parallel for generality. This is rare code.
2895 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2896 curhw = curhw + cur->size();
2897 }
2898 assert(curhw == t, "Should have parsed correctly.");
2899 }
2900 if (G1PolicyVerbose > 1) {
2901 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2902 "for survivors:", r->bottom(), original_top, r->end());
2903 r->print();
2904 }
2905 g1_policy()->record_before_bytes(r_used);
2906 }
2907 }
2909 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2910 assert(Thread::current()->is_VM_thread() ||
2911 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2912 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2913 "Precondition.");
2914 hr->set_is_gc_alloc_region(true);
2915 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2916 _gc_alloc_region_list = hr;
2917 }
2919 #ifdef G1_DEBUG
2920 class FindGCAllocRegion: public HeapRegionClosure {
2921 public:
2922 bool doHeapRegion(HeapRegion* r) {
2923 if (r->is_gc_alloc_region()) {
2924 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2925 r->hrs_index(), r->bottom());
2926 }
2927 return false;
2928 }
2929 };
2930 #endif // G1_DEBUG
2932 void G1CollectedHeap::forget_alloc_region_list() {
2933 assert(Thread::current()->is_VM_thread(), "Precondition");
2934 while (_gc_alloc_region_list != NULL) {
2935 HeapRegion* r = _gc_alloc_region_list;
2936 assert(r->is_gc_alloc_region(), "Invariant.");
2937 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
2938 // newly allocated data in order to be able to apply deferred updates
2939 // before the GC is done for verification purposes (i.e to allow
2940 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
2941 // collection.
2942 r->ContiguousSpace::set_saved_mark();
2943 _gc_alloc_region_list = r->next_gc_alloc_region();
2944 r->set_next_gc_alloc_region(NULL);
2945 r->set_is_gc_alloc_region(false);
2946 if (r->is_survivor()) {
2947 if (r->is_empty()) {
2948 r->set_not_young();
2949 } else {
2950 _young_list->add_survivor_region(r);
2951 }
2952 }
2953 if (r->is_empty()) {
2954 ++_free_regions;
2955 }
2956 }
2957 #ifdef G1_DEBUG
2958 FindGCAllocRegion fa;
2959 heap_region_iterate(&fa);
2960 #endif // G1_DEBUG
2961 }
2964 bool G1CollectedHeap::check_gc_alloc_regions() {
2965 // TODO: allocation regions check
2966 return true;
2967 }
2969 void G1CollectedHeap::get_gc_alloc_regions() {
2970 // First, let's check that the GC alloc region list is empty (it should)
2971 assert(_gc_alloc_region_list == NULL, "invariant");
2973 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2974 assert(_gc_alloc_regions[ap] == NULL, "invariant");
2975 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
2977 // Create new GC alloc regions.
2978 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
2979 _retained_gc_alloc_regions[ap] = NULL;
2981 if (alloc_region != NULL) {
2982 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
2984 // let's make sure that the GC alloc region is not tagged as such
2985 // outside a GC operation
2986 assert(!alloc_region->is_gc_alloc_region(), "sanity");
2988 if (alloc_region->in_collection_set() ||
2989 alloc_region->top() == alloc_region->end() ||
2990 alloc_region->top() == alloc_region->bottom()) {
2991 // we will discard the current GC alloc region if it's in the
2992 // collection set (it can happen!), if it's already full (no
2993 // point in using it), or if it's empty (this means that it
2994 // was emptied during a cleanup and it should be on the free
2995 // list now).
2997 alloc_region = NULL;
2998 }
2999 }
3001 if (alloc_region == NULL) {
3002 // we will get a new GC alloc region
3003 alloc_region = newAllocRegionWithExpansion(ap, 0);
3004 } else {
3005 // the region was retained from the last collection
3006 ++_gc_alloc_region_counts[ap];
3007 }
3009 if (alloc_region != NULL) {
3010 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3011 set_gc_alloc_region(ap, alloc_region);
3012 }
3014 assert(_gc_alloc_regions[ap] == NULL ||
3015 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3016 "the GC alloc region should be tagged as such");
3017 assert(_gc_alloc_regions[ap] == NULL ||
3018 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3019 "the GC alloc region should be the same as the GC alloc list head");
3020 }
3021 // Set alternative regions for allocation purposes that have reached
3022 // their limit.
3023 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3024 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3025 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3026 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3027 }
3028 }
3029 assert(check_gc_alloc_regions(), "alloc regions messed up");
3030 }
3032 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3033 // We keep a separate list of all regions that have been alloc regions in
3034 // the current collection pause. Forget that now. This method will
3035 // untag the GC alloc regions and tear down the GC alloc region
3036 // list. It's desirable that no regions are tagged as GC alloc
3037 // outside GCs.
3038 forget_alloc_region_list();
3040 // The current alloc regions contain objs that have survived
3041 // collection. Make them no longer GC alloc regions.
3042 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3043 HeapRegion* r = _gc_alloc_regions[ap];
3044 _retained_gc_alloc_regions[ap] = NULL;
3045 _gc_alloc_region_counts[ap] = 0;
3047 if (r != NULL) {
3048 // we retain nothing on _gc_alloc_regions between GCs
3049 set_gc_alloc_region(ap, NULL);
3051 if (r->is_empty()) {
3052 // we didn't actually allocate anything in it; let's just put
3053 // it on the free list
3054 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
3055 r->set_zero_fill_complete();
3056 put_free_region_on_list_locked(r);
3057 } else if (_retain_gc_alloc_region[ap] && !totally) {
3058 // retain it so that we can use it at the beginning of the next GC
3059 _retained_gc_alloc_regions[ap] = r;
3060 }
3061 }
3062 }
3063 }
3065 #ifndef PRODUCT
3066 // Useful for debugging
3068 void G1CollectedHeap::print_gc_alloc_regions() {
3069 gclog_or_tty->print_cr("GC alloc regions");
3070 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3071 HeapRegion* r = _gc_alloc_regions[ap];
3072 if (r == NULL) {
3073 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3074 } else {
3075 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3076 ap, r->bottom(), r->used());
3077 }
3078 }
3079 }
3080 #endif // PRODUCT
3082 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3083 _drain_in_progress = false;
3084 set_evac_failure_closure(cl);
3085 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3086 }
3088 void G1CollectedHeap::finalize_for_evac_failure() {
3089 assert(_evac_failure_scan_stack != NULL &&
3090 _evac_failure_scan_stack->length() == 0,
3091 "Postcondition");
3092 assert(!_drain_in_progress, "Postcondition");
3093 // Don't have to delete, since the scan stack is a resource object.
3094 _evac_failure_scan_stack = NULL;
3095 }
3099 // *** Sequential G1 Evacuation
3101 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3102 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3103 // let the caller handle alloc failure
3104 if (alloc_region == NULL) return NULL;
3105 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3106 "Either the object is humongous or the region isn't");
3107 HeapWord* block = alloc_region->allocate(word_size);
3108 if (block == NULL) {
3109 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3110 }
3111 return block;
3112 }
3114 class G1IsAliveClosure: public BoolObjectClosure {
3115 G1CollectedHeap* _g1;
3116 public:
3117 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3118 void do_object(oop p) { assert(false, "Do not call."); }
3119 bool do_object_b(oop p) {
3120 // It is reachable if it is outside the collection set, or is inside
3121 // and forwarded.
3123 #ifdef G1_DEBUG
3124 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3125 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3126 !_g1->obj_in_cs(p) || p->is_forwarded());
3127 #endif // G1_DEBUG
3129 return !_g1->obj_in_cs(p) || p->is_forwarded();
3130 }
3131 };
3133 class G1KeepAliveClosure: public OopClosure {
3134 G1CollectedHeap* _g1;
3135 public:
3136 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3137 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3138 void do_oop( oop* p) {
3139 oop obj = *p;
3140 #ifdef G1_DEBUG
3141 if (PrintGC && Verbose) {
3142 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3143 p, (void*) obj, (void*) *p);
3144 }
3145 #endif // G1_DEBUG
3147 if (_g1->obj_in_cs(obj)) {
3148 assert( obj->is_forwarded(), "invariant" );
3149 *p = obj->forwardee();
3150 #ifdef G1_DEBUG
3151 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3152 (void*) obj, (void*) *p);
3153 #endif // G1_DEBUG
3154 }
3155 }
3156 };
3158 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3159 private:
3160 G1CollectedHeap* _g1;
3161 G1RemSet* _g1_rem_set;
3162 public:
3163 UpdateRSetImmediate(G1CollectedHeap* g1) :
3164 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3166 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3167 virtual void do_oop( oop* p) { do_oop_work(p); }
3168 template <class T> void do_oop_work(T* p) {
3169 assert(_from->is_in_reserved(p), "paranoia");
3170 T heap_oop = oopDesc::load_heap_oop(p);
3171 if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
3172 _g1_rem_set->par_write_ref(_from, p, 0);
3173 }
3174 }
3175 };
3177 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3178 private:
3179 G1CollectedHeap* _g1;
3180 DirtyCardQueue *_dcq;
3181 CardTableModRefBS* _ct_bs;
3183 public:
3184 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3185 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3187 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3188 virtual void do_oop( oop* p) { do_oop_work(p); }
3189 template <class T> void do_oop_work(T* p) {
3190 assert(_from->is_in_reserved(p), "paranoia");
3191 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3192 !_from->is_survivor()) {
3193 size_t card_index = _ct_bs->index_for(p);
3194 if (_ct_bs->mark_card_deferred(card_index)) {
3195 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3196 }
3197 }
3198 }
3199 };
3203 class RemoveSelfPointerClosure: public ObjectClosure {
3204 private:
3205 G1CollectedHeap* _g1;
3206 ConcurrentMark* _cm;
3207 HeapRegion* _hr;
3208 size_t _prev_marked_bytes;
3209 size_t _next_marked_bytes;
3210 OopsInHeapRegionClosure *_cl;
3211 public:
3212 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3213 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3214 _next_marked_bytes(0), _cl(cl) {}
3216 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3217 size_t next_marked_bytes() { return _next_marked_bytes; }
3219 // The original idea here was to coalesce evacuated and dead objects.
3220 // However that caused complications with the block offset table (BOT).
3221 // In particular if there were two TLABs, one of them partially refined.
3222 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3223 // The BOT entries of the unrefined part of TLAB_2 point to the start
3224 // of TLAB_2. If the last object of the TLAB_1 and the first object
3225 // of TLAB_2 are coalesced, then the cards of the unrefined part
3226 // would point into middle of the filler object.
3227 //
3228 // The current approach is to not coalesce and leave the BOT contents intact.
3229 void do_object(oop obj) {
3230 if (obj->is_forwarded() && obj->forwardee() == obj) {
3231 // The object failed to move.
3232 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3233 _cm->markPrev(obj);
3234 assert(_cm->isPrevMarked(obj), "Should be marked!");
3235 _prev_marked_bytes += (obj->size() * HeapWordSize);
3236 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3237 _cm->markAndGrayObjectIfNecessary(obj);
3238 }
3239 obj->set_mark(markOopDesc::prototype());
3240 // While we were processing RSet buffers during the
3241 // collection, we actually didn't scan any cards on the
3242 // collection set, since we didn't want to update remebered
3243 // sets with entries that point into the collection set, given
3244 // that live objects fromthe collection set are about to move
3245 // and such entries will be stale very soon. This change also
3246 // dealt with a reliability issue which involved scanning a
3247 // card in the collection set and coming across an array that
3248 // was being chunked and looking malformed. The problem is
3249 // that, if evacuation fails, we might have remembered set
3250 // entries missing given that we skipped cards on the
3251 // collection set. So, we'll recreate such entries now.
3252 obj->oop_iterate(_cl);
3253 assert(_cm->isPrevMarked(obj), "Should be marked!");
3254 } else {
3255 // The object has been either evacuated or is dead. Fill it with a
3256 // dummy object.
3257 MemRegion mr((HeapWord*)obj, obj->size());
3258 CollectedHeap::fill_with_object(mr);
3259 _cm->clearRangeBothMaps(mr);
3260 }
3261 }
3262 };
3264 void G1CollectedHeap::remove_self_forwarding_pointers() {
3265 UpdateRSetImmediate immediate_update(_g1h);
3266 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3267 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3268 OopsInHeapRegionClosure *cl;
3269 if (G1DeferredRSUpdate) {
3270 cl = &deferred_update;
3271 } else {
3272 cl = &immediate_update;
3273 }
3274 HeapRegion* cur = g1_policy()->collection_set();
3275 while (cur != NULL) {
3276 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3278 RemoveSelfPointerClosure rspc(_g1h, cl);
3279 if (cur->evacuation_failed()) {
3280 assert(cur->in_collection_set(), "bad CS");
3281 cl->set_region(cur);
3282 cur->object_iterate(&rspc);
3284 // A number of manipulations to make the TAMS be the current top,
3285 // and the marked bytes be the ones observed in the iteration.
3286 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3287 // The comments below are the postconditions achieved by the
3288 // calls. Note especially the last such condition, which says that
3289 // the count of marked bytes has been properly restored.
3290 cur->note_start_of_marking(false);
3291 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3292 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3293 // _next_marked_bytes == prev_marked_bytes.
3294 cur->note_end_of_marking();
3295 // _prev_top_at_mark_start == top(),
3296 // _prev_marked_bytes == prev_marked_bytes
3297 }
3298 // If there is no mark in progress, we modified the _next variables
3299 // above needlessly, but harmlessly.
3300 if (_g1h->mark_in_progress()) {
3301 cur->note_start_of_marking(false);
3302 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3303 // _next_marked_bytes == next_marked_bytes.
3304 }
3306 // Now make sure the region has the right index in the sorted array.
3307 g1_policy()->note_change_in_marked_bytes(cur);
3308 }
3309 cur = cur->next_in_collection_set();
3310 }
3311 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3313 // Now restore saved marks, if any.
3314 if (_objs_with_preserved_marks != NULL) {
3315 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3316 assert(_objs_with_preserved_marks->length() ==
3317 _preserved_marks_of_objs->length(), "Both or none.");
3318 guarantee(_objs_with_preserved_marks->length() ==
3319 _preserved_marks_of_objs->length(), "Both or none.");
3320 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3321 oop obj = _objs_with_preserved_marks->at(i);
3322 markOop m = _preserved_marks_of_objs->at(i);
3323 obj->set_mark(m);
3324 }
3325 // Delete the preserved marks growable arrays (allocated on the C heap).
3326 delete _objs_with_preserved_marks;
3327 delete _preserved_marks_of_objs;
3328 _objs_with_preserved_marks = NULL;
3329 _preserved_marks_of_objs = NULL;
3330 }
3331 }
3333 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3334 _evac_failure_scan_stack->push(obj);
3335 }
3337 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3338 assert(_evac_failure_scan_stack != NULL, "precondition");
3340 while (_evac_failure_scan_stack->length() > 0) {
3341 oop obj = _evac_failure_scan_stack->pop();
3342 _evac_failure_closure->set_region(heap_region_containing(obj));
3343 obj->oop_iterate_backwards(_evac_failure_closure);
3344 }
3345 }
3347 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3348 markOop m = old->mark();
3349 // forward to self
3350 assert(!old->is_forwarded(), "precondition");
3352 old->forward_to(old);
3353 handle_evacuation_failure_common(old, m);
3354 }
3356 oop
3357 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3358 oop old) {
3359 markOop m = old->mark();
3360 oop forward_ptr = old->forward_to_atomic(old);
3361 if (forward_ptr == NULL) {
3362 // Forward-to-self succeeded.
3363 if (_evac_failure_closure != cl) {
3364 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3365 assert(!_drain_in_progress,
3366 "Should only be true while someone holds the lock.");
3367 // Set the global evac-failure closure to the current thread's.
3368 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3369 set_evac_failure_closure(cl);
3370 // Now do the common part.
3371 handle_evacuation_failure_common(old, m);
3372 // Reset to NULL.
3373 set_evac_failure_closure(NULL);
3374 } else {
3375 // The lock is already held, and this is recursive.
3376 assert(_drain_in_progress, "This should only be the recursive case.");
3377 handle_evacuation_failure_common(old, m);
3378 }
3379 return old;
3380 } else {
3381 // Someone else had a place to copy it.
3382 return forward_ptr;
3383 }
3384 }
3386 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3387 set_evacuation_failed(true);
3389 preserve_mark_if_necessary(old, m);
3391 HeapRegion* r = heap_region_containing(old);
3392 if (!r->evacuation_failed()) {
3393 r->set_evacuation_failed(true);
3394 if (G1PrintRegions) {
3395 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3396 "["PTR_FORMAT","PTR_FORMAT")\n",
3397 r, r->bottom(), r->end());
3398 }
3399 }
3401 push_on_evac_failure_scan_stack(old);
3403 if (!_drain_in_progress) {
3404 // prevent recursion in copy_to_survivor_space()
3405 _drain_in_progress = true;
3406 drain_evac_failure_scan_stack();
3407 _drain_in_progress = false;
3408 }
3409 }
3411 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3412 if (m != markOopDesc::prototype()) {
3413 if (_objs_with_preserved_marks == NULL) {
3414 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3415 _objs_with_preserved_marks =
3416 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3417 _preserved_marks_of_objs =
3418 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3419 }
3420 _objs_with_preserved_marks->push(obj);
3421 _preserved_marks_of_objs->push(m);
3422 }
3423 }
3425 // *** Parallel G1 Evacuation
3427 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3428 size_t word_size) {
3429 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3430 // let the caller handle alloc failure
3431 if (alloc_region == NULL) return NULL;
3433 HeapWord* block = alloc_region->par_allocate(word_size);
3434 if (block == NULL) {
3435 MutexLockerEx x(par_alloc_during_gc_lock(),
3436 Mutex::_no_safepoint_check_flag);
3437 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3438 }
3439 return block;
3440 }
3442 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3443 bool par) {
3444 // Another thread might have obtained alloc_region for the given
3445 // purpose, and might be attempting to allocate in it, and might
3446 // succeed. Therefore, we can't do the "finalization" stuff on the
3447 // region below until we're sure the last allocation has happened.
3448 // We ensure this by allocating the remaining space with a garbage
3449 // object.
3450 if (par) par_allocate_remaining_space(alloc_region);
3451 // Now we can do the post-GC stuff on the region.
3452 alloc_region->note_end_of_copying();
3453 g1_policy()->record_after_bytes(alloc_region->used());
3454 }
3456 HeapWord*
3457 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3458 HeapRegion* alloc_region,
3459 bool par,
3460 size_t word_size) {
3461 HeapWord* block = NULL;
3462 // In the parallel case, a previous thread to obtain the lock may have
3463 // already assigned a new gc_alloc_region.
3464 if (alloc_region != _gc_alloc_regions[purpose]) {
3465 assert(par, "But should only happen in parallel case.");
3466 alloc_region = _gc_alloc_regions[purpose];
3467 if (alloc_region == NULL) return NULL;
3468 block = alloc_region->par_allocate(word_size);
3469 if (block != NULL) return block;
3470 // Otherwise, continue; this new region is empty, too.
3471 }
3472 assert(alloc_region != NULL, "We better have an allocation region");
3473 retire_alloc_region(alloc_region, par);
3475 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3476 // Cannot allocate more regions for the given purpose.
3477 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3478 // Is there an alternative?
3479 if (purpose != alt_purpose) {
3480 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3481 // Has not the alternative region been aliased?
3482 if (alloc_region != alt_region && alt_region != NULL) {
3483 // Try to allocate in the alternative region.
3484 if (par) {
3485 block = alt_region->par_allocate(word_size);
3486 } else {
3487 block = alt_region->allocate(word_size);
3488 }
3489 // Make an alias.
3490 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3491 if (block != NULL) {
3492 return block;
3493 }
3494 retire_alloc_region(alt_region, par);
3495 }
3496 // Both the allocation region and the alternative one are full
3497 // and aliased, replace them with a new allocation region.
3498 purpose = alt_purpose;
3499 } else {
3500 set_gc_alloc_region(purpose, NULL);
3501 return NULL;
3502 }
3503 }
3505 // Now allocate a new region for allocation.
3506 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3508 // let the caller handle alloc failure
3509 if (alloc_region != NULL) {
3511 assert(check_gc_alloc_regions(), "alloc regions messed up");
3512 assert(alloc_region->saved_mark_at_top(),
3513 "Mark should have been saved already.");
3514 // We used to assert that the region was zero-filled here, but no
3515 // longer.
3517 // This must be done last: once it's installed, other regions may
3518 // allocate in it (without holding the lock.)
3519 set_gc_alloc_region(purpose, alloc_region);
3521 if (par) {
3522 block = alloc_region->par_allocate(word_size);
3523 } else {
3524 block = alloc_region->allocate(word_size);
3525 }
3526 // Caller handles alloc failure.
3527 } else {
3528 // This sets other apis using the same old alloc region to NULL, also.
3529 set_gc_alloc_region(purpose, NULL);
3530 }
3531 return block; // May be NULL.
3532 }
3534 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3535 HeapWord* block = NULL;
3536 size_t free_words;
3537 do {
3538 free_words = r->free()/HeapWordSize;
3539 // If there's too little space, no one can allocate, so we're done.
3540 if (free_words < (size_t)oopDesc::header_size()) return;
3541 // Otherwise, try to claim it.
3542 block = r->par_allocate(free_words);
3543 } while (block == NULL);
3544 fill_with_object(block, free_words);
3545 }
3547 #ifndef PRODUCT
3548 bool GCLabBitMapClosure::do_bit(size_t offset) {
3549 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3550 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3551 return true;
3552 }
3553 #endif // PRODUCT
3555 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3556 : _g1h(g1h),
3557 _refs(g1h->task_queue(queue_num)),
3558 _dcq(&g1h->dirty_card_queue_set()),
3559 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3560 _g1_rem(g1h->g1_rem_set()),
3561 _hash_seed(17), _queue_num(queue_num),
3562 _term_attempts(0),
3563 _age_table(false),
3564 #if G1_DETAILED_STATS
3565 _pushes(0), _pops(0), _steals(0),
3566 _steal_attempts(0), _overflow_pushes(0),
3567 #endif
3568 _strong_roots_time(0), _term_time(0),
3569 _alloc_buffer_waste(0), _undo_waste(0)
3570 {
3571 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3572 // we "sacrifice" entry 0 to keep track of surviving bytes for
3573 // non-young regions (where the age is -1)
3574 // We also add a few elements at the beginning and at the end in
3575 // an attempt to eliminate cache contention
3576 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3577 size_t array_length = PADDING_ELEM_NUM +
3578 real_length +
3579 PADDING_ELEM_NUM;
3580 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3581 if (_surviving_young_words_base == NULL)
3582 vm_exit_out_of_memory(array_length * sizeof(size_t),
3583 "Not enough space for young surv histo.");
3584 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3585 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3587 _overflowed_refs = new OverflowQueue(10);
3589 _start = os::elapsedTime();
3590 }
3592 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3593 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3594 _par_scan_state(par_scan_state) { }
3596 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
3597 // This is called _after_ do_oop_work has been called, hence after
3598 // the object has been relocated to its new location and *p points
3599 // to its new location.
3601 T heap_oop = oopDesc::load_heap_oop(p);
3602 if (!oopDesc::is_null(heap_oop)) {
3603 oop obj = oopDesc::decode_heap_oop(heap_oop);
3604 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
3605 "shouldn't still be in the CSet if evacuation didn't fail.");
3606 HeapWord* addr = (HeapWord*)obj;
3607 if (_g1->is_in_g1_reserved(addr))
3608 _cm->grayRoot(oop(addr));
3609 }
3610 }
3612 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3613 size_t word_sz = old->size();
3614 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3615 // +1 to make the -1 indexes valid...
3616 int young_index = from_region->young_index_in_cset()+1;
3617 assert( (from_region->is_young() && young_index > 0) ||
3618 (!from_region->is_young() && young_index == 0), "invariant" );
3619 G1CollectorPolicy* g1p = _g1->g1_policy();
3620 markOop m = old->mark();
3621 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3622 : m->age();
3623 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3624 word_sz);
3625 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3626 oop obj = oop(obj_ptr);
3628 if (obj_ptr == NULL) {
3629 // This will either forward-to-self, or detect that someone else has
3630 // installed a forwarding pointer.
3631 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3632 return _g1->handle_evacuation_failure_par(cl, old);
3633 }
3635 // We're going to allocate linearly, so might as well prefetch ahead.
3636 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
3638 oop forward_ptr = old->forward_to_atomic(obj);
3639 if (forward_ptr == NULL) {
3640 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3641 if (g1p->track_object_age(alloc_purpose)) {
3642 // We could simply do obj->incr_age(). However, this causes a
3643 // performance issue. obj->incr_age() will first check whether
3644 // the object has a displaced mark by checking its mark word;
3645 // getting the mark word from the new location of the object
3646 // stalls. So, given that we already have the mark word and we
3647 // are about to install it anyway, it's better to increase the
3648 // age on the mark word, when the object does not have a
3649 // displaced mark word. We're not expecting many objects to have
3650 // a displaced marked word, so that case is not optimized
3651 // further (it could be...) and we simply call obj->incr_age().
3653 if (m->has_displaced_mark_helper()) {
3654 // in this case, we have to install the mark word first,
3655 // otherwise obj looks to be forwarded (the old mark word,
3656 // which contains the forward pointer, was copied)
3657 obj->set_mark(m);
3658 obj->incr_age();
3659 } else {
3660 m = m->incr_age();
3661 obj->set_mark(m);
3662 }
3663 _par_scan_state->age_table()->add(obj, word_sz);
3664 } else {
3665 obj->set_mark(m);
3666 }
3668 // preserve "next" mark bit
3669 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3670 if (!use_local_bitmaps ||
3671 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3672 // if we couldn't mark it on the local bitmap (this happens when
3673 // the object was not allocated in the GCLab), we have to bite
3674 // the bullet and do the standard parallel mark
3675 _cm->markAndGrayObjectIfNecessary(obj);
3676 }
3677 #if 1
3678 if (_g1->isMarkedNext(old)) {
3679 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3680 }
3681 #endif
3682 }
3684 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3685 surv_young_words[young_index] += word_sz;
3687 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3688 arrayOop(old)->set_length(0);
3689 oop* old_p = set_partial_array_mask(old);
3690 _par_scan_state->push_on_queue(old_p);
3691 } else {
3692 // No point in using the slower heap_region_containing() method,
3693 // given that we know obj is in the heap.
3694 _scanner->set_region(_g1->heap_region_containing_raw(obj));
3695 obj->oop_iterate_backwards(_scanner);
3696 }
3697 } else {
3698 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3699 obj = forward_ptr;
3700 }
3701 return obj;
3702 }
3704 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee, bool skip_cset_test>
3705 template <class T>
3706 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee, skip_cset_test>
3707 ::do_oop_work(T* p) {
3708 oop obj = oopDesc::load_decode_heap_oop(p);
3709 assert(barrier != G1BarrierRS || obj != NULL,
3710 "Precondition: G1BarrierRS implies obj is nonNull");
3712 // The only time we skip the cset test is when we're scanning
3713 // references popped from the queue. And we only push on the queue
3714 // references that we know point into the cset, so no point in
3715 // checking again. But we'll leave an assert here for peace of mind.
3716 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
3718 // here the null check is implicit in the cset_fast_test() test
3719 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
3720 #if G1_REM_SET_LOGGING
3721 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
3722 "into CS.", p, (void*) obj);
3723 #endif
3724 if (obj->is_forwarded()) {
3725 oopDesc::encode_store_heap_oop(p, obj->forwardee());
3726 } else {
3727 oop copy_oop = copy_to_survivor_space(obj);
3728 oopDesc::encode_store_heap_oop(p, copy_oop);
3729 }
3730 // When scanning the RS, we only care about objs in CS.
3731 if (barrier == G1BarrierRS) {
3732 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3733 }
3734 }
3736 // When scanning moved objs, must look at all oops.
3737 if (barrier == G1BarrierEvac && obj != NULL) {
3738 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3739 }
3741 if (do_gen_barrier && obj != NULL) {
3742 par_do_barrier(p);
3743 }
3744 }
3746 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
3747 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(narrowOop* p);
3749 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
3750 assert(has_partial_array_mask(p), "invariant");
3751 oop old = clear_partial_array_mask(p);
3752 assert(old->is_objArray(), "must be obj array");
3753 assert(old->is_forwarded(), "must be forwarded");
3754 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
3756 objArrayOop obj = objArrayOop(old->forwardee());
3757 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
3758 // Process ParGCArrayScanChunk elements now
3759 // and push the remainder back onto queue
3760 int start = arrayOop(old)->length();
3761 int end = obj->length();
3762 int remainder = end - start;
3763 assert(start <= end, "just checking");
3764 if (remainder > 2 * ParGCArrayScanChunk) {
3765 // Test above combines last partial chunk with a full chunk
3766 end = start + ParGCArrayScanChunk;
3767 arrayOop(old)->set_length(end);
3768 // Push remainder.
3769 oop* old_p = set_partial_array_mask(old);
3770 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
3771 _par_scan_state->push_on_queue(old_p);
3772 } else {
3773 // Restore length so that the heap remains parsable in
3774 // case of evacuation failure.
3775 arrayOop(old)->set_length(end);
3776 }
3777 _scanner.set_region(_g1->heap_region_containing_raw(obj));
3778 // process our set of indices (include header in first chunk)
3779 obj->oop_iterate_range(&_scanner, start, end);
3780 }
3782 class G1ParEvacuateFollowersClosure : public VoidClosure {
3783 protected:
3784 G1CollectedHeap* _g1h;
3785 G1ParScanThreadState* _par_scan_state;
3786 RefToScanQueueSet* _queues;
3787 ParallelTaskTerminator* _terminator;
3789 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3790 RefToScanQueueSet* queues() { return _queues; }
3791 ParallelTaskTerminator* terminator() { return _terminator; }
3793 public:
3794 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
3795 G1ParScanThreadState* par_scan_state,
3796 RefToScanQueueSet* queues,
3797 ParallelTaskTerminator* terminator)
3798 : _g1h(g1h), _par_scan_state(par_scan_state),
3799 _queues(queues), _terminator(terminator) {}
3801 void do_void() {
3802 G1ParScanThreadState* pss = par_scan_state();
3803 while (true) {
3804 pss->trim_queue();
3805 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
3807 StarTask stolen_task;
3808 if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
3809 IF_G1_DETAILED_STATS(pss->note_steal());
3811 // slightly paranoid tests; I'm trying to catch potential
3812 // problems before we go into push_on_queue to know where the
3813 // problem is coming from
3814 assert((oop*)stolen_task != NULL, "Error");
3815 if (stolen_task.is_narrow()) {
3816 assert(UseCompressedOops, "Error");
3817 narrowOop* p = (narrowOop*) stolen_task;
3818 assert(has_partial_array_mask(p) ||
3819 _g1h->obj_in_cs(oopDesc::load_decode_heap_oop(p)), "Error");
3820 pss->push_on_queue(p);
3821 } else {
3822 oop* p = (oop*) stolen_task;
3823 assert(has_partial_array_mask(p) || _g1h->obj_in_cs(*p), "Error");
3824 pss->push_on_queue(p);
3825 }
3826 continue;
3827 }
3828 pss->start_term_time();
3829 if (terminator()->offer_termination()) break;
3830 pss->end_term_time();
3831 }
3832 pss->end_term_time();
3833 pss->retire_alloc_buffers();
3834 }
3835 };
3837 class G1ParTask : public AbstractGangTask {
3838 protected:
3839 G1CollectedHeap* _g1h;
3840 RefToScanQueueSet *_queues;
3841 ParallelTaskTerminator _terminator;
3842 int _n_workers;
3844 Mutex _stats_lock;
3845 Mutex* stats_lock() { return &_stats_lock; }
3847 size_t getNCards() {
3848 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
3849 / G1BlockOffsetSharedArray::N_bytes;
3850 }
3852 public:
3853 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
3854 : AbstractGangTask("G1 collection"),
3855 _g1h(g1h),
3856 _queues(task_queues),
3857 _terminator(workers, _queues),
3858 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
3859 _n_workers(workers)
3860 {}
3862 RefToScanQueueSet* queues() { return _queues; }
3864 RefToScanQueue *work_queue(int i) {
3865 return queues()->queue(i);
3866 }
3868 void work(int i) {
3869 if (i >= _n_workers) return; // no work needed this round
3870 ResourceMark rm;
3871 HandleMark hm;
3873 G1ParScanThreadState pss(_g1h, i);
3874 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
3875 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
3876 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
3878 pss.set_evac_closure(&scan_evac_cl);
3879 pss.set_evac_failure_closure(&evac_failure_cl);
3880 pss.set_partial_scan_closure(&partial_scan_cl);
3882 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
3883 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
3884 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
3886 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
3887 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
3888 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
3890 OopsInHeapRegionClosure *scan_root_cl;
3891 OopsInHeapRegionClosure *scan_perm_cl;
3892 OopsInHeapRegionClosure *scan_so_cl;
3894 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
3895 scan_root_cl = &scan_mark_root_cl;
3896 scan_perm_cl = &scan_mark_perm_cl;
3897 scan_so_cl = &scan_mark_heap_rs_cl;
3898 } else {
3899 scan_root_cl = &only_scan_root_cl;
3900 scan_perm_cl = &only_scan_perm_cl;
3901 scan_so_cl = &only_scan_heap_rs_cl;
3902 }
3904 pss.start_strong_roots();
3905 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
3906 SharedHeap::SO_AllClasses,
3907 scan_root_cl,
3908 &only_scan_heap_rs_cl,
3909 scan_so_cl,
3910 scan_perm_cl,
3911 i);
3912 pss.end_strong_roots();
3913 {
3914 double start = os::elapsedTime();
3915 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
3916 evac.do_void();
3917 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
3918 double term_ms = pss.term_time()*1000.0;
3919 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
3920 _g1h->g1_policy()->record_termination_time(i, term_ms);
3921 }
3922 if (G1UseSurvivorSpaces) {
3923 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
3924 }
3925 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
3927 // Clean up any par-expanded rem sets.
3928 HeapRegionRemSet::par_cleanup();
3930 MutexLocker x(stats_lock());
3931 if (ParallelGCVerbose) {
3932 gclog_or_tty->print("Thread %d complete:\n", i);
3933 #if G1_DETAILED_STATS
3934 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
3935 pss.pushes(),
3936 pss.pops(),
3937 pss.overflow_pushes(),
3938 pss.steals(),
3939 pss.steal_attempts());
3940 #endif
3941 double elapsed = pss.elapsed();
3942 double strong_roots = pss.strong_roots_time();
3943 double term = pss.term_time();
3944 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
3945 " Strong roots: %7.2f ms (%6.2f%%)\n"
3946 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
3947 elapsed * 1000.0,
3948 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
3949 term * 1000.0, (term*100.0/elapsed),
3950 pss.term_attempts());
3951 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
3952 gclog_or_tty->print(" Waste: %8dK\n"
3953 " Alloc Buffer: %8dK\n"
3954 " Undo: %8dK\n",
3955 (total_waste * HeapWordSize) / K,
3956 (pss.alloc_buffer_waste() * HeapWordSize) / K,
3957 (pss.undo_waste() * HeapWordSize) / K);
3958 }
3960 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
3961 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
3962 }
3963 };
3965 // *** Common G1 Evacuation Stuff
3967 void
3968 G1CollectedHeap::
3969 g1_process_strong_roots(bool collecting_perm_gen,
3970 SharedHeap::ScanningOption so,
3971 OopClosure* scan_non_heap_roots,
3972 OopsInHeapRegionClosure* scan_rs,
3973 OopsInHeapRegionClosure* scan_so,
3974 OopsInGenClosure* scan_perm,
3975 int worker_i) {
3976 // First scan the strong roots, including the perm gen.
3977 double ext_roots_start = os::elapsedTime();
3978 double closure_app_time_sec = 0.0;
3980 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
3981 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
3982 buf_scan_perm.set_generation(perm_gen());
3984 process_strong_roots(collecting_perm_gen, so,
3985 &buf_scan_non_heap_roots,
3986 &buf_scan_perm);
3987 // Finish up any enqueued closure apps.
3988 buf_scan_non_heap_roots.done();
3989 buf_scan_perm.done();
3990 double ext_roots_end = os::elapsedTime();
3991 g1_policy()->reset_obj_copy_time(worker_i);
3992 double obj_copy_time_sec =
3993 buf_scan_non_heap_roots.closure_app_seconds() +
3994 buf_scan_perm.closure_app_seconds();
3995 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
3996 double ext_root_time_ms =
3997 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
3998 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4000 // Scan strong roots in mark stack.
4001 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4002 concurrent_mark()->oops_do(scan_non_heap_roots);
4003 }
4004 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4005 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4007 // XXX What should this be doing in the parallel case?
4008 g1_policy()->record_collection_pause_end_CH_strong_roots();
4009 if (scan_so != NULL) {
4010 scan_scan_only_set(scan_so, worker_i);
4011 }
4012 // Now scan the complement of the collection set.
4013 if (scan_rs != NULL) {
4014 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4015 }
4016 // Finish with the ref_processor roots.
4017 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4018 ref_processor()->oops_do(scan_non_heap_roots);
4019 }
4020 g1_policy()->record_collection_pause_end_G1_strong_roots();
4021 _process_strong_tasks->all_tasks_completed();
4022 }
4024 void
4025 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4026 OopsInHeapRegionClosure* oc,
4027 int worker_i) {
4028 HeapWord* startAddr = r->bottom();
4029 HeapWord* endAddr = r->used_region().end();
4031 oc->set_region(r);
4033 HeapWord* p = r->bottom();
4034 HeapWord* t = r->top();
4035 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4036 while (p < t) {
4037 oop obj = oop(p);
4038 p += obj->oop_iterate(oc);
4039 }
4040 }
4042 void
4043 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4044 int worker_i) {
4045 double start = os::elapsedTime();
4047 BufferingOopsInHeapRegionClosure boc(oc);
4049 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4050 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4052 OopsInHeapRegionClosure *foc;
4053 if (g1_policy()->should_initiate_conc_mark())
4054 foc = &scan_and_mark;
4055 else
4056 foc = &scan_only;
4058 HeapRegion* hr;
4059 int n = 0;
4060 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4061 scan_scan_only_region(hr, foc, worker_i);
4062 ++n;
4063 }
4064 boc.done();
4066 double closure_app_s = boc.closure_app_seconds();
4067 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4068 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4069 g1_policy()->record_scan_only_time(worker_i, ms, n);
4070 }
4072 void
4073 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4074 OopClosure* non_root_closure) {
4075 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4076 }
4079 class SaveMarksClosure: public HeapRegionClosure {
4080 public:
4081 bool doHeapRegion(HeapRegion* r) {
4082 r->save_marks();
4083 return false;
4084 }
4085 };
4087 void G1CollectedHeap::save_marks() {
4088 if (ParallelGCThreads == 0) {
4089 SaveMarksClosure sm;
4090 heap_region_iterate(&sm);
4091 }
4092 // We do this even in the parallel case
4093 perm_gen()->save_marks();
4094 }
4096 void G1CollectedHeap::evacuate_collection_set() {
4097 set_evacuation_failed(false);
4099 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4100 concurrent_g1_refine()->set_use_cache(false);
4101 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4103 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4104 set_par_threads(n_workers);
4105 G1ParTask g1_par_task(this, n_workers, _task_queues);
4107 init_for_evac_failure(NULL);
4109 change_strong_roots_parity(); // In preparation for parallel strong roots.
4110 rem_set()->prepare_for_younger_refs_iterate(true);
4112 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4113 double start_par = os::elapsedTime();
4114 if (ParallelGCThreads > 0) {
4115 // The individual threads will set their evac-failure closures.
4116 workers()->run_task(&g1_par_task);
4117 } else {
4118 g1_par_task.work(0);
4119 }
4121 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4122 g1_policy()->record_par_time(par_time);
4123 set_par_threads(0);
4124 // Is this the right thing to do here? We don't save marks
4125 // on individual heap regions when we allocate from
4126 // them in parallel, so this seems like the correct place for this.
4127 retire_all_alloc_regions();
4128 {
4129 G1IsAliveClosure is_alive(this);
4130 G1KeepAliveClosure keep_alive(this);
4131 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4132 }
4133 release_gc_alloc_regions(false /* totally */);
4134 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4136 concurrent_g1_refine()->clear_hot_cache();
4137 concurrent_g1_refine()->set_use_cache(true);
4139 finalize_for_evac_failure();
4141 // Must do this before removing self-forwarding pointers, which clears
4142 // the per-region evac-failure flags.
4143 concurrent_mark()->complete_marking_in_collection_set();
4145 if (evacuation_failed()) {
4146 remove_self_forwarding_pointers();
4147 if (PrintGCDetails) {
4148 gclog_or_tty->print(" (evacuation failed)");
4149 } else if (PrintGC) {
4150 gclog_or_tty->print("--");
4151 }
4152 }
4154 if (G1DeferredRSUpdate) {
4155 RedirtyLoggedCardTableEntryFastClosure redirty;
4156 dirty_card_queue_set().set_closure(&redirty);
4157 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4158 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4159 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4160 }
4162 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4163 }
4165 void G1CollectedHeap::free_region(HeapRegion* hr) {
4166 size_t pre_used = 0;
4167 size_t cleared_h_regions = 0;
4168 size_t freed_regions = 0;
4169 UncleanRegionList local_list;
4171 HeapWord* start = hr->bottom();
4172 HeapWord* end = hr->prev_top_at_mark_start();
4173 size_t used_bytes = hr->used();
4174 size_t live_bytes = hr->max_live_bytes();
4175 if (used_bytes > 0) {
4176 guarantee( live_bytes <= used_bytes, "invariant" );
4177 } else {
4178 guarantee( live_bytes == 0, "invariant" );
4179 }
4181 size_t garbage_bytes = used_bytes - live_bytes;
4182 if (garbage_bytes > 0)
4183 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4185 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4186 &local_list);
4187 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4188 &local_list);
4189 }
4191 void
4192 G1CollectedHeap::free_region_work(HeapRegion* hr,
4193 size_t& pre_used,
4194 size_t& cleared_h_regions,
4195 size_t& freed_regions,
4196 UncleanRegionList* list,
4197 bool par) {
4198 pre_used += hr->used();
4199 if (hr->isHumongous()) {
4200 assert(hr->startsHumongous(),
4201 "Only the start of a humongous region should be freed.");
4202 int ind = _hrs->find(hr);
4203 assert(ind != -1, "Should have an index.");
4204 // Clear the start region.
4205 hr->hr_clear(par, true /*clear_space*/);
4206 list->insert_before_head(hr);
4207 cleared_h_regions++;
4208 freed_regions++;
4209 // Clear any continued regions.
4210 ind++;
4211 while ((size_t)ind < n_regions()) {
4212 HeapRegion* hrc = _hrs->at(ind);
4213 if (!hrc->continuesHumongous()) break;
4214 // Otherwise, does continue the H region.
4215 assert(hrc->humongous_start_region() == hr, "Huh?");
4216 hrc->hr_clear(par, true /*clear_space*/);
4217 cleared_h_regions++;
4218 freed_regions++;
4219 list->insert_before_head(hrc);
4220 ind++;
4221 }
4222 } else {
4223 hr->hr_clear(par, true /*clear_space*/);
4224 list->insert_before_head(hr);
4225 freed_regions++;
4226 // If we're using clear2, this should not be enabled.
4227 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4228 }
4229 }
4231 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4232 size_t cleared_h_regions,
4233 size_t freed_regions,
4234 UncleanRegionList* list) {
4235 if (list != NULL && list->sz() > 0) {
4236 prepend_region_list_on_unclean_list(list);
4237 }
4238 // Acquire a lock, if we're parallel, to update possibly-shared
4239 // variables.
4240 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4241 {
4242 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4243 _summary_bytes_used -= pre_used;
4244 _num_humongous_regions -= (int) cleared_h_regions;
4245 _free_regions += freed_regions;
4246 }
4247 }
4250 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4251 while (list != NULL) {
4252 guarantee( list->is_young(), "invariant" );
4254 HeapWord* bottom = list->bottom();
4255 HeapWord* end = list->end();
4256 MemRegion mr(bottom, end);
4257 ct_bs->dirty(mr);
4259 list = list->get_next_young_region();
4260 }
4261 }
4264 class G1ParCleanupCTTask : public AbstractGangTask {
4265 CardTableModRefBS* _ct_bs;
4266 G1CollectedHeap* _g1h;
4267 HeapRegion* volatile _so_head;
4268 HeapRegion* volatile _su_head;
4269 public:
4270 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4271 G1CollectedHeap* g1h,
4272 HeapRegion* scan_only_list,
4273 HeapRegion* survivor_list) :
4274 AbstractGangTask("G1 Par Cleanup CT Task"),
4275 _ct_bs(ct_bs),
4276 _g1h(g1h),
4277 _so_head(scan_only_list),
4278 _su_head(survivor_list)
4279 { }
4281 void work(int i) {
4282 HeapRegion* r;
4283 while (r = _g1h->pop_dirty_cards_region()) {
4284 clear_cards(r);
4285 }
4286 // Redirty the cards of the scan-only and survivor regions.
4287 dirty_list(&this->_so_head);
4288 dirty_list(&this->_su_head);
4289 }
4291 void clear_cards(HeapRegion* r) {
4292 // Cards for Survivor and Scan-Only regions will be dirtied later.
4293 if (!r->is_scan_only() && !r->is_survivor()) {
4294 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4295 }
4296 }
4298 void dirty_list(HeapRegion* volatile * head_ptr) {
4299 HeapRegion* head;
4300 do {
4301 // Pop region off the list.
4302 head = *head_ptr;
4303 if (head != NULL) {
4304 HeapRegion* r = (HeapRegion*)
4305 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4306 if (r == head) {
4307 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4308 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4309 }
4310 }
4311 } while (*head_ptr != NULL);
4312 }
4313 };
4316 #ifndef PRODUCT
4317 class G1VerifyCardTableCleanup: public HeapRegionClosure {
4318 CardTableModRefBS* _ct_bs;
4319 public:
4320 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
4321 : _ct_bs(ct_bs)
4322 { }
4323 virtual bool doHeapRegion(HeapRegion* r)
4324 {
4325 MemRegion mr(r->bottom(), r->end());
4326 if (r->is_scan_only() || r->is_survivor()) {
4327 _ct_bs->verify_dirty_region(mr);
4328 } else {
4329 _ct_bs->verify_clean_region(mr);
4330 }
4331 return false;
4332 }
4333 };
4334 #endif
4336 void G1CollectedHeap::cleanUpCardTable() {
4337 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4338 double start = os::elapsedTime();
4340 // Iterate over the dirty cards region list.
4341 G1ParCleanupCTTask cleanup_task(ct_bs, this,
4342 _young_list->first_scan_only_region(),
4343 _young_list->first_survivor_region());
4344 if (ParallelGCThreads > 0) {
4345 set_par_threads(workers()->total_workers());
4346 workers()->run_task(&cleanup_task);
4347 set_par_threads(0);
4348 } else {
4349 while (_dirty_cards_region_list) {
4350 HeapRegion* r = _dirty_cards_region_list;
4351 cleanup_task.clear_cards(r);
4352 _dirty_cards_region_list = r->get_next_dirty_cards_region();
4353 if (_dirty_cards_region_list == r) {
4354 // The last region.
4355 _dirty_cards_region_list = NULL;
4356 }
4357 r->set_next_dirty_cards_region(NULL);
4358 }
4359 // now, redirty the cards of the scan-only and survivor regions
4360 // (it seemed faster to do it this way, instead of iterating over
4361 // all regions and then clearing / dirtying as appropriate)
4362 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4363 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4364 }
4365 double elapsed = os::elapsedTime() - start;
4366 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4367 #ifndef PRODUCT
4368 if (G1VerifyCTCleanup || VerifyAfterGC) {
4369 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
4370 heap_region_iterate(&cleanup_verifier);
4371 }
4372 #endif
4373 }
4375 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4376 if (g1_policy()->should_do_collection_pause(word_size)) {
4377 do_collection_pause();
4378 }
4379 }
4381 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4382 double young_time_ms = 0.0;
4383 double non_young_time_ms = 0.0;
4385 G1CollectorPolicy* policy = g1_policy();
4387 double start_sec = os::elapsedTime();
4388 bool non_young = true;
4390 HeapRegion* cur = cs_head;
4391 int age_bound = -1;
4392 size_t rs_lengths = 0;
4394 while (cur != NULL) {
4395 if (non_young) {
4396 if (cur->is_young()) {
4397 double end_sec = os::elapsedTime();
4398 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4399 non_young_time_ms += elapsed_ms;
4401 start_sec = os::elapsedTime();
4402 non_young = false;
4403 }
4404 } else {
4405 if (!cur->is_on_free_list()) {
4406 double end_sec = os::elapsedTime();
4407 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4408 young_time_ms += elapsed_ms;
4410 start_sec = os::elapsedTime();
4411 non_young = true;
4412 }
4413 }
4415 rs_lengths += cur->rem_set()->occupied();
4417 HeapRegion* next = cur->next_in_collection_set();
4418 assert(cur->in_collection_set(), "bad CS");
4419 cur->set_next_in_collection_set(NULL);
4420 cur->set_in_collection_set(false);
4422 if (cur->is_young()) {
4423 int index = cur->young_index_in_cset();
4424 guarantee( index != -1, "invariant" );
4425 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4426 size_t words_survived = _surviving_young_words[index];
4427 cur->record_surv_words_in_group(words_survived);
4428 } else {
4429 int index = cur->young_index_in_cset();
4430 guarantee( index == -1, "invariant" );
4431 }
4433 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4434 (!cur->is_young() && cur->young_index_in_cset() == -1),
4435 "invariant" );
4437 if (!cur->evacuation_failed()) {
4438 // And the region is empty.
4439 assert(!cur->is_empty(),
4440 "Should not have empty regions in a CS.");
4441 free_region(cur);
4442 } else {
4443 guarantee( !cur->is_scan_only(), "should not be scan only" );
4444 cur->uninstall_surv_rate_group();
4445 if (cur->is_young())
4446 cur->set_young_index_in_cset(-1);
4447 cur->set_not_young();
4448 cur->set_evacuation_failed(false);
4449 }
4450 cur = next;
4451 }
4453 policy->record_max_rs_lengths(rs_lengths);
4454 policy->cset_regions_freed();
4456 double end_sec = os::elapsedTime();
4457 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4458 if (non_young)
4459 non_young_time_ms += elapsed_ms;
4460 else
4461 young_time_ms += elapsed_ms;
4463 policy->record_young_free_cset_time_ms(young_time_ms);
4464 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4465 }
4467 HeapRegion*
4468 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4469 assert(ZF_mon->owned_by_self(), "Precondition");
4470 HeapRegion* res = pop_unclean_region_list_locked();
4471 if (res != NULL) {
4472 assert(!res->continuesHumongous() &&
4473 res->zero_fill_state() != HeapRegion::Allocated,
4474 "Only free regions on unclean list.");
4475 if (zero_filled) {
4476 res->ensure_zero_filled_locked();
4477 res->set_zero_fill_allocated();
4478 }
4479 }
4480 return res;
4481 }
4483 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4484 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4485 return alloc_region_from_unclean_list_locked(zero_filled);
4486 }
4488 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4489 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4490 put_region_on_unclean_list_locked(r);
4491 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4492 }
4494 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4495 MutexLockerEx x(Cleanup_mon);
4496 set_unclean_regions_coming_locked(b);
4497 }
4499 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4500 assert(Cleanup_mon->owned_by_self(), "Precondition");
4501 _unclean_regions_coming = b;
4502 // Wake up mutator threads that might be waiting for completeCleanup to
4503 // finish.
4504 if (!b) Cleanup_mon->notify_all();
4505 }
4507 void G1CollectedHeap::wait_for_cleanup_complete() {
4508 MutexLockerEx x(Cleanup_mon);
4509 wait_for_cleanup_complete_locked();
4510 }
4512 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4513 assert(Cleanup_mon->owned_by_self(), "precondition");
4514 while (_unclean_regions_coming) {
4515 Cleanup_mon->wait();
4516 }
4517 }
4519 void
4520 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4521 assert(ZF_mon->owned_by_self(), "precondition.");
4522 _unclean_region_list.insert_before_head(r);
4523 }
4525 void
4526 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4527 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4528 prepend_region_list_on_unclean_list_locked(list);
4529 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4530 }
4532 void
4533 G1CollectedHeap::
4534 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4535 assert(ZF_mon->owned_by_self(), "precondition.");
4536 _unclean_region_list.prepend_list(list);
4537 }
4539 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4540 assert(ZF_mon->owned_by_self(), "precondition.");
4541 HeapRegion* res = _unclean_region_list.pop();
4542 if (res != NULL) {
4543 // Inform ZF thread that there's a new unclean head.
4544 if (_unclean_region_list.hd() != NULL && should_zf())
4545 ZF_mon->notify_all();
4546 }
4547 return res;
4548 }
4550 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4551 assert(ZF_mon->owned_by_self(), "precondition.");
4552 return _unclean_region_list.hd();
4553 }
4556 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4557 assert(ZF_mon->owned_by_self(), "Precondition");
4558 HeapRegion* r = peek_unclean_region_list_locked();
4559 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4560 // Result of below must be equal to "r", since we hold the lock.
4561 (void)pop_unclean_region_list_locked();
4562 put_free_region_on_list_locked(r);
4563 return true;
4564 } else {
4565 return false;
4566 }
4567 }
4569 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4570 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4571 return move_cleaned_region_to_free_list_locked();
4572 }
4575 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4576 assert(ZF_mon->owned_by_self(), "precondition.");
4577 assert(_free_region_list_size == free_region_list_length(), "Inv");
4578 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4579 "Regions on free list must be zero filled");
4580 assert(!r->isHumongous(), "Must not be humongous.");
4581 assert(r->is_empty(), "Better be empty");
4582 assert(!r->is_on_free_list(),
4583 "Better not already be on free list");
4584 assert(!r->is_on_unclean_list(),
4585 "Better not already be on unclean list");
4586 r->set_on_free_list(true);
4587 r->set_next_on_free_list(_free_region_list);
4588 _free_region_list = r;
4589 _free_region_list_size++;
4590 assert(_free_region_list_size == free_region_list_length(), "Inv");
4591 }
4593 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4594 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4595 put_free_region_on_list_locked(r);
4596 }
4598 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4599 assert(ZF_mon->owned_by_self(), "precondition.");
4600 assert(_free_region_list_size == free_region_list_length(), "Inv");
4601 HeapRegion* res = _free_region_list;
4602 if (res != NULL) {
4603 _free_region_list = res->next_from_free_list();
4604 _free_region_list_size--;
4605 res->set_on_free_list(false);
4606 res->set_next_on_free_list(NULL);
4607 assert(_free_region_list_size == free_region_list_length(), "Inv");
4608 }
4609 return res;
4610 }
4613 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4614 // By self, or on behalf of self.
4615 assert(Heap_lock->is_locked(), "Precondition");
4616 HeapRegion* res = NULL;
4617 bool first = true;
4618 while (res == NULL) {
4619 if (zero_filled || !first) {
4620 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4621 res = pop_free_region_list_locked();
4622 if (res != NULL) {
4623 assert(!res->zero_fill_is_allocated(),
4624 "No allocated regions on free list.");
4625 res->set_zero_fill_allocated();
4626 } else if (!first) {
4627 break; // We tried both, time to return NULL.
4628 }
4629 }
4631 if (res == NULL) {
4632 res = alloc_region_from_unclean_list(zero_filled);
4633 }
4634 assert(res == NULL ||
4635 !zero_filled ||
4636 res->zero_fill_is_allocated(),
4637 "We must have allocated the region we're returning");
4638 first = false;
4639 }
4640 return res;
4641 }
4643 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4644 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4645 {
4646 HeapRegion* prev = NULL;
4647 HeapRegion* cur = _unclean_region_list.hd();
4648 while (cur != NULL) {
4649 HeapRegion* next = cur->next_from_unclean_list();
4650 if (cur->zero_fill_is_allocated()) {
4651 // Remove from the list.
4652 if (prev == NULL) {
4653 (void)_unclean_region_list.pop();
4654 } else {
4655 _unclean_region_list.delete_after(prev);
4656 }
4657 cur->set_on_unclean_list(false);
4658 cur->set_next_on_unclean_list(NULL);
4659 } else {
4660 prev = cur;
4661 }
4662 cur = next;
4663 }
4664 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4665 "Inv");
4666 }
4668 {
4669 HeapRegion* prev = NULL;
4670 HeapRegion* cur = _free_region_list;
4671 while (cur != NULL) {
4672 HeapRegion* next = cur->next_from_free_list();
4673 if (cur->zero_fill_is_allocated()) {
4674 // Remove from the list.
4675 if (prev == NULL) {
4676 _free_region_list = cur->next_from_free_list();
4677 } else {
4678 prev->set_next_on_free_list(cur->next_from_free_list());
4679 }
4680 cur->set_on_free_list(false);
4681 cur->set_next_on_free_list(NULL);
4682 _free_region_list_size--;
4683 } else {
4684 prev = cur;
4685 }
4686 cur = next;
4687 }
4688 assert(_free_region_list_size == free_region_list_length(), "Inv");
4689 }
4690 }
4692 bool G1CollectedHeap::verify_region_lists() {
4693 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4694 return verify_region_lists_locked();
4695 }
4697 bool G1CollectedHeap::verify_region_lists_locked() {
4698 HeapRegion* unclean = _unclean_region_list.hd();
4699 while (unclean != NULL) {
4700 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4701 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4702 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4703 "Everything else is possible.");
4704 unclean = unclean->next_from_unclean_list();
4705 }
4706 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4708 HeapRegion* free_r = _free_region_list;
4709 while (free_r != NULL) {
4710 assert(free_r->is_on_free_list(), "Well, it is!");
4711 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4712 switch (free_r->zero_fill_state()) {
4713 case HeapRegion::NotZeroFilled:
4714 case HeapRegion::ZeroFilling:
4715 guarantee(false, "Should not be on free list.");
4716 break;
4717 default:
4718 // Everything else is possible.
4719 break;
4720 }
4721 free_r = free_r->next_from_free_list();
4722 }
4723 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4724 // If we didn't do an assertion...
4725 return true;
4726 }
4728 size_t G1CollectedHeap::free_region_list_length() {
4729 assert(ZF_mon->owned_by_self(), "precondition.");
4730 size_t len = 0;
4731 HeapRegion* cur = _free_region_list;
4732 while (cur != NULL) {
4733 len++;
4734 cur = cur->next_from_free_list();
4735 }
4736 return len;
4737 }
4739 size_t G1CollectedHeap::unclean_region_list_length() {
4740 assert(ZF_mon->owned_by_self(), "precondition.");
4741 return _unclean_region_list.length();
4742 }
4744 size_t G1CollectedHeap::n_regions() {
4745 return _hrs->length();
4746 }
4748 size_t G1CollectedHeap::max_regions() {
4749 return
4750 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4751 HeapRegion::GrainBytes;
4752 }
4754 size_t G1CollectedHeap::free_regions() {
4755 /* Possibly-expensive assert.
4756 assert(_free_regions == count_free_regions(),
4757 "_free_regions is off.");
4758 */
4759 return _free_regions;
4760 }
4762 bool G1CollectedHeap::should_zf() {
4763 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4764 }
4766 class RegionCounter: public HeapRegionClosure {
4767 size_t _n;
4768 public:
4769 RegionCounter() : _n(0) {}
4770 bool doHeapRegion(HeapRegion* r) {
4771 if (r->is_empty()) {
4772 assert(!r->isHumongous(), "H regions should not be empty.");
4773 _n++;
4774 }
4775 return false;
4776 }
4777 int res() { return (int) _n; }
4778 };
4780 size_t G1CollectedHeap::count_free_regions() {
4781 RegionCounter rc;
4782 heap_region_iterate(&rc);
4783 size_t n = rc.res();
4784 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4785 n--;
4786 return n;
4787 }
4789 size_t G1CollectedHeap::count_free_regions_list() {
4790 size_t n = 0;
4791 size_t o = 0;
4792 ZF_mon->lock_without_safepoint_check();
4793 HeapRegion* cur = _free_region_list;
4794 while (cur != NULL) {
4795 cur = cur->next_from_free_list();
4796 n++;
4797 }
4798 size_t m = unclean_region_list_length();
4799 ZF_mon->unlock();
4800 return n + m;
4801 }
4803 bool G1CollectedHeap::should_set_young_locked() {
4804 assert(heap_lock_held_for_gc(),
4805 "the heap lock should already be held by or for this thread");
4806 return (g1_policy()->in_young_gc_mode() &&
4807 g1_policy()->should_add_next_region_to_young_list());
4808 }
4810 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4811 assert(heap_lock_held_for_gc(),
4812 "the heap lock should already be held by or for this thread");
4813 _young_list->push_region(hr);
4814 g1_policy()->set_region_short_lived(hr);
4815 }
4817 class NoYoungRegionsClosure: public HeapRegionClosure {
4818 private:
4819 bool _success;
4820 public:
4821 NoYoungRegionsClosure() : _success(true) { }
4822 bool doHeapRegion(HeapRegion* r) {
4823 if (r->is_young()) {
4824 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
4825 r->bottom(), r->end());
4826 _success = false;
4827 }
4828 return false;
4829 }
4830 bool success() { return _success; }
4831 };
4833 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
4834 bool check_sample) {
4835 bool ret = true;
4837 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
4838 if (!ignore_scan_only_list) {
4839 NoYoungRegionsClosure closure;
4840 heap_region_iterate(&closure);
4841 ret = ret && closure.success();
4842 }
4844 return ret;
4845 }
4847 void G1CollectedHeap::empty_young_list() {
4848 assert(heap_lock_held_for_gc(),
4849 "the heap lock should already be held by or for this thread");
4850 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
4852 _young_list->empty_list();
4853 }
4855 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
4856 bool no_allocs = true;
4857 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
4858 HeapRegion* r = _gc_alloc_regions[ap];
4859 no_allocs = r == NULL || r->saved_mark_at_top();
4860 }
4861 return no_allocs;
4862 }
4864 void G1CollectedHeap::retire_all_alloc_regions() {
4865 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4866 HeapRegion* r = _gc_alloc_regions[ap];
4867 if (r != NULL) {
4868 // Check for aliases.
4869 bool has_processed_alias = false;
4870 for (int i = 0; i < ap; ++i) {
4871 if (_gc_alloc_regions[i] == r) {
4872 has_processed_alias = true;
4873 break;
4874 }
4875 }
4876 if (!has_processed_alias) {
4877 retire_alloc_region(r, false /* par */);
4878 }
4879 }
4880 }
4881 }
4884 // Done at the start of full GC.
4885 void G1CollectedHeap::tear_down_region_lists() {
4886 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4887 while (pop_unclean_region_list_locked() != NULL) ;
4888 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
4889 "Postconditions of loop.")
4890 while (pop_free_region_list_locked() != NULL) ;
4891 assert(_free_region_list == NULL, "Postcondition of loop.");
4892 if (_free_region_list_size != 0) {
4893 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
4894 print_on(gclog_or_tty, true /* extended */);
4895 }
4896 assert(_free_region_list_size == 0, "Postconditions of loop.");
4897 }
4900 class RegionResetter: public HeapRegionClosure {
4901 G1CollectedHeap* _g1;
4902 int _n;
4903 public:
4904 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4905 bool doHeapRegion(HeapRegion* r) {
4906 if (r->continuesHumongous()) return false;
4907 if (r->top() > r->bottom()) {
4908 if (r->top() < r->end()) {
4909 Copy::fill_to_words(r->top(),
4910 pointer_delta(r->end(), r->top()));
4911 }
4912 r->set_zero_fill_allocated();
4913 } else {
4914 assert(r->is_empty(), "tautology");
4915 _n++;
4916 switch (r->zero_fill_state()) {
4917 case HeapRegion::NotZeroFilled:
4918 case HeapRegion::ZeroFilling:
4919 _g1->put_region_on_unclean_list_locked(r);
4920 break;
4921 case HeapRegion::Allocated:
4922 r->set_zero_fill_complete();
4923 // no break; go on to put on free list.
4924 case HeapRegion::ZeroFilled:
4925 _g1->put_free_region_on_list_locked(r);
4926 break;
4927 }
4928 }
4929 return false;
4930 }
4932 int getFreeRegionCount() {return _n;}
4933 };
4935 // Done at the end of full GC.
4936 void G1CollectedHeap::rebuild_region_lists() {
4937 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4938 // This needs to go at the end of the full GC.
4939 RegionResetter rs;
4940 heap_region_iterate(&rs);
4941 _free_regions = rs.getFreeRegionCount();
4942 // Tell the ZF thread it may have work to do.
4943 if (should_zf()) ZF_mon->notify_all();
4944 }
4946 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
4947 G1CollectedHeap* _g1;
4948 int _n;
4949 public:
4950 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4951 bool doHeapRegion(HeapRegion* r) {
4952 if (r->continuesHumongous()) return false;
4953 if (r->top() > r->bottom()) {
4954 // There are assertions in "set_zero_fill_needed()" below that
4955 // require top() == bottom(), so this is technically illegal.
4956 // We'll skirt the law here, by making that true temporarily.
4957 DEBUG_ONLY(HeapWord* save_top = r->top();
4958 r->set_top(r->bottom()));
4959 r->set_zero_fill_needed();
4960 DEBUG_ONLY(r->set_top(save_top));
4961 }
4962 return false;
4963 }
4964 };
4966 // Done at the start of full GC.
4967 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
4968 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4969 // This needs to go at the end of the full GC.
4970 UsedRegionsNeedZeroFillSetter rs;
4971 heap_region_iterate(&rs);
4972 }
4974 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
4975 _refine_cte_cl->set_concurrent(concurrent);
4976 }
4978 #ifndef PRODUCT
4980 class PrintHeapRegionClosure: public HeapRegionClosure {
4981 public:
4982 bool doHeapRegion(HeapRegion *r) {
4983 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
4984 if (r != NULL) {
4985 if (r->is_on_free_list())
4986 gclog_or_tty->print("Free ");
4987 if (r->is_young())
4988 gclog_or_tty->print("Young ");
4989 if (r->isHumongous())
4990 gclog_or_tty->print("Is Humongous ");
4991 r->print();
4992 }
4993 return false;
4994 }
4995 };
4997 class SortHeapRegionClosure : public HeapRegionClosure {
4998 size_t young_regions,free_regions, unclean_regions;
4999 size_t hum_regions, count;
5000 size_t unaccounted, cur_unclean, cur_alloc;
5001 size_t total_free;
5002 HeapRegion* cur;
5003 public:
5004 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5005 free_regions(0), unclean_regions(0),
5006 hum_regions(0),
5007 count(0), unaccounted(0),
5008 cur_alloc(0), total_free(0)
5009 {}
5010 bool doHeapRegion(HeapRegion *r) {
5011 count++;
5012 if (r->is_on_free_list()) free_regions++;
5013 else if (r->is_on_unclean_list()) unclean_regions++;
5014 else if (r->isHumongous()) hum_regions++;
5015 else if (r->is_young()) young_regions++;
5016 else if (r == cur) cur_alloc++;
5017 else unaccounted++;
5018 return false;
5019 }
5020 void print() {
5021 total_free = free_regions + unclean_regions;
5022 gclog_or_tty->print("%d regions\n", count);
5023 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5024 total_free, free_regions, unclean_regions);
5025 gclog_or_tty->print("%d humongous %d young\n",
5026 hum_regions, young_regions);
5027 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5028 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5029 }
5030 };
5032 void G1CollectedHeap::print_region_counts() {
5033 SortHeapRegionClosure sc(_cur_alloc_region);
5034 PrintHeapRegionClosure cl;
5035 heap_region_iterate(&cl);
5036 heap_region_iterate(&sc);
5037 sc.print();
5038 print_region_accounting_info();
5039 };
5041 bool G1CollectedHeap::regions_accounted_for() {
5042 // TODO: regions accounting for young/survivor/tenured
5043 return true;
5044 }
5046 bool G1CollectedHeap::print_region_accounting_info() {
5047 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5048 free_regions(),
5049 count_free_regions(), count_free_regions_list(),
5050 _free_region_list_size, _unclean_region_list.sz());
5051 gclog_or_tty->print_cr("cur_alloc: %d.",
5052 (_cur_alloc_region == NULL ? 0 : 1));
5053 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5055 // TODO: check regions accounting for young/survivor/tenured
5056 return true;
5057 }
5059 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5060 HeapRegion* hr = heap_region_containing(p);
5061 if (hr == NULL) {
5062 return is_in_permanent(p);
5063 } else {
5064 return hr->is_in(p);
5065 }
5066 }
5067 #endif // PRODUCT
5069 void G1CollectedHeap::g1_unimplemented() {
5070 // Unimplemented();
5071 }